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

  1. Synthesis and catalytic application of magnetic Co-Cu nanowires.

    PubMed

    Sun, Lijuan; Li, Xiaoyu; Xu, Zhiqiang; Xie, Kenan; Liao, Li

    2017-01-01

    A rapid, template-free method was developed to prepare magnetic, bimetallic Co-Cu nanowires via liquid phase reduction and metal replacement under an external magnetic field. The characterization results confirmed that the as-prepared product was bimetallic Co-Cu nanowires with a desirable linear structure. Additionally, the magnetic hysteresis loop showed that the bimetallic Co-Cu nanowires were paramagnetic, which meant they could be easily separated from the reaction mixture. Furthermore, they were applied to the hydrolysis system of ammonia borane as a catalyst for the first time. More importantly, the catalysis results showed that the bimetallic nanowires possessed appealing catalytic performance. Therefore, a rapid and facile synthesis method is introduced which is capable of preparing bimetallic Co-Cu nanowires with great potential for industrial applications.

  2. Magnetic properties of Co Cu nanoparticles dispersed in silica matrix

    NASA Astrophysics Data System (ADS)

    de Julián Fernández, C.; Mattei, G.; Maurizio, C.; Cattaruzza, E.; Padovani, S.; Battaglin, G.; Gonella, F.; D'Acapito, F.; Mazzoldi, P.

    2005-04-01

    The magnetic properties of Co-Cu/silica nanocomposites prepared by sequential ion implantation have been investigated. The nanostructure is formed of 4 nm average size particles dispersed in silica matrix and with mainly FCC structure. The hysteresis loops at 3 K indicate that the nanoparticles have uniaxial anisotropy with values smaller than that of single Cobalt implants. The samples are characterized by a superparamagnetic behavior with blocking temperatures that depend on the Co/Cu implanted ratio, and the blocking temperature distributions are narrower than those obtained by taking into account only the particle size distribution. Results are discussed considering size effects and that the nanoparticles are formed of a Co-Cu solid solution or only of Co.

  3. Microstructure and magnetic property of Co/Cu multilayers

    SciTech Connect

    Kim, P.D.; Song, J.H.; Turpanov, I.A.; Komogortsev, S.V.; Semenov, L.I.; Karpenko, M.M.; Jeong, Y.H.

    1999-09-01

    Co/Cu multilayers consisting of 120 bilayers, [Co(3.5{angstrom})/Cu(t)]{sub 120} with t = 15.8 {angstrom} and 18.3 {angstrom}, were fabricated on glass substrates by dc magnetron sputtering, and their magnetic properties were investigated. The Co layers in a multilayer are found to be an aggregate of ferromagnetic and superparamagnetic Co clusters dispersed in a Cu matrix. The present Co/Cu multilayers are revealed to be periodically modulated granular alloys with stochastic ferromagnetic structure.

  4. Magnetothermoelectric figure of merit of Co/Cu multilayers

    SciTech Connect

    Hu, X. K. Krzysteczko, P.; Liebing, N.; Schumacher, H. W.; Serrano-Guisan, S.; Rott, K.; Reiss, G.; Kimling, J.; Böhnert, T.; Nielsch, K.

    2014-03-03

    The switching of the magnetic configuration of giant magnetoresistance multilayers not only changes the electrical and thermal conductivities but also the thermopower. We study the magnetotransport and the magnetothermoelectric properties of Co/Cu multilayer devices in a lateral thermal gradient. The Seebeck coefficient reaches values up to −18 μV/K at room temperature and shows a magnetic field dependence up to 28.6% upon spin reversal. In combination with thermal conductivity data of the same Co/Cu stack, we find a magnetothermoelectric figure of merit of up to 65%. Furthermore, a magneto-power factor of up to 110% is derived.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. 2D Magnetic Texture Analysis of Co-Cu Films

    NASA Astrophysics Data System (ADS)

    Bayirli, Mehmet; Karaagac, Oznur; Kockar, Hakan; Alper, Mursel

    2017-05-01

    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 Co2+ in the electrolyte. In addition, the easy-axis orientation in the films from the squareness values of the angles, Mp(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 Co2+ in the electrolyte. The coefficients of Fourier series (A0 and A2n ) were also computed for 2D films. It is seen that a systematic and small decrease in A0 and an obvious decrease in A2n (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.

  7. Mechanical characterization of Co/Cu multilayered nanowires.

    PubMed

    Jiménez-Sáez, J C; Pérez-Martin, A M C; Jiménez-Rodríguez, J J

    2012-06-01

    The mechanical deformation properties of (110) Co/Cu multilayered nanowires were studied by Molecular Dynamics under uniaxial tensile and compressive stresses. The potential of the immiscible CoCu system was modeled by a second-moment tight-binding approximation. Stress-strain curves at different conditions were obtained and the elastic modulus and yield stress were analyzed. Both magnitudes are approximately independent of the strain rate, except at high values. They decrease linearly with increasing temperature. Below a volume-to-surface-area ratio, their values drastically increase and diverge from the bulk values. If the thickness of the Cu sublayers increases, the Young's modulus and yield stress decrease, although in a different way. The elastic modulus decreases linearly and the yield stress falls steeply whenever Cu is present in the nanowire, since the lattice distortion takes place firstly and fundamentally in Cu sublayers. The change in the axial stress at the interface is little significant on average and rather localized. Unlike, the transverse stress has a non-uniform distribution along the Cu sublayer, especially at the yield point. The Young's modulus and yield stress are larger in tension than in compression. Under tensile stress, nanowires slip via partial dislocation nucleation and propagation. Unlike, compressive deformation of nanowires takes place via both partial and full dislocations.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Sm-Co-Cu-Ti high-temperature permanent magnets

    SciTech Connect

    Zhou, J.; Skomski, R.; Chen, C.; Hadjipanayis, G. C.; Sellmyer, D. J.

    2000-09-04

    A class of promising permanent-magnet materials with an appreciable high-temperature coercivity of 8.6 kOe at 500 degree sign C is reported. The Sm-Co-Cu-Ti magnets are prepared by arc melting and require a suitable heat treatment. Magnetization measurements as a function of temperature and x-ray diffraction patterns indicate that the samples are two-phase mixtures of 2:17 and 1:5 structures. Depending on heat treatment and composition, some of the magnets exhibit a positive temperature coefficient of coercivity. The promising high-temperature behavior of the coercivity is ascribed to the temperature dependence of the domain-wall energy, which affects the curvature of the walls and the pinning behavior. (c) 2000 American Institute of Physics.

  11. Sm-Co-Cu-Ti high-temperature permanent magnets

    NASA Astrophysics Data System (ADS)

    Zhou, J.; Skomski, R.; Chen, C.; Hadjipanayis, G. C.; Sellmyer, D. J.

    2000-09-01

    A class of promising permanent-magnet materials with an appreciable high-temperature coercivity of 8.6 kOe at 500 °C is reported. The Sm-Co-Cu-Ti magnets are prepared by arc melting and require a suitable heat treatment. Magnetization measurements as a function of temperature and x-ray diffraction patterns indicate that the samples are two-phase mixtures of 2:17 and 1:5 structures. Depending on heat treatment and composition, some of the magnets exhibit a positive temperature coefficient of coercivity. The promising high-temperature behavior of the coercivity is ascribed to the temperature dependence of the domain-wall energy, which affects the curvature of the walls and the pinning behavior.

  12. Growth and characterisation of electrodeposited Co/Cu superlattices.

    PubMed

    Safak, Mürşide; Alper, Mürsel; Kockar, Hakan

    2008-02-01

    Ferromagnetic/non-ferromagnetic Co/Cu superlattices were grown on polycrystalline Titanium (Ti) from a single electrolyte by electrodeposition. Microstructure and magnetoresistance (MR) of the superlattices were investigated as a function of the electrolyte pH as well as the layer thicknesses. Structural characterisation by X-ray diffraction (XRD) showed that the superlattices have face-centred cubic (fcc) structure with a strong (111) texture at the studied pH levels, but the texture degree is affected by the electrolyte pH. The scanning electron microscope (SEM) studies revealed that the superlattices grown at low pH (2.0) have smoother surfaces compared to those grown at high pH (3.0). The superlattices exhibited either anisotropic magnetoresistance (AMR) or giant magnetoresistance (GMR) depending on the Cu layer thickness. The shape of MR curves changes depending on the combination of Co and Cu layer thicknesses. The superlattices with Co layers less than 3 nm and Cu layers less than 2 nm have broad and non-saturating curves, indicating the predominance of a superparamagnetic contribution, possibly due to the discontinuous nature of the ferromagnetic (Co) layer. For superlattices with the same bilayer and total thicknesses, the GMR magnitude decreased as the electrolyte pH increased. Besides possible structural differences such as the texture degree and the surface roughness, this may arises from the variation in the Cu content of the ferromagnetic layers caused by the electrolyte pH.

  13. Carbon encapsulated nanoparticles of Ni, Co, Cu, and Ti

    NASA Astrophysics Data System (ADS)

    Jiao, Jun; Seraphin, Supapan

    1998-03-01

    Despite intensive research on the encapsulation of metal nanoparticles into carbon clusters deposited by arc discharge, the detailed pathways of the formation of these novel forms of materials remain unclear. The growth of a rich variety of morphologies is not well understood. Studies are reported here on the growth phenomena of different metals encapsulated into carbon cages that emphasize the effect of carbon and metal supply on the size of particles. Post-deposition annealing was introduced as a process that induces structural rearrangements, and thus enables changes in morphologies. A set of carbon encapsulated Ni, Co, Cu, and Ti particles were prepared by an arc discharge process modified in the geometry of the anode and flow pattern of helium or methane gas. The samples were then annealed under flowing argon gas. Three annealing temperatures were used (600, 900, and 1100 °C). Samples were characterized by transmission and scanning electron microscopy. Particles made under the same experimental conditions are of roughly the same size. When the supply of metal in the reactor space was increased by using a larger diameter of the metal pool, the average diameter of the particles is bigger than those of produced from the smaller metal pool. The thickness of the carbon cages of Ni and Co particles increased during the annealing. The carbon cages of Cu particles, however, did not change their thickness, while some carbon coatings of Ti particles disappeared under annealing. This suggests that the addition of layers for the Ni and Co cages results from a precipitation of carbon previously dissolved in the metal, while the much lower solubility of C in Cu prevents this possibility. The Ti of high reactivity, on the other hand, may further react with the available carbon under annealing to form TiC. It is suggested that annealing provides additional thermal energy that makes structural re-arrangement possible long after the initial deposition process was terminated

  14. Tuning giant magnetoresistance in rolled-up Co-Cu nanomembranes by strain engineering.

    PubMed

    Müller, Christian; Bof Bufon, Carlos Cesar; Makarov, Denys; Fernandez-Outon, Luis E; Macedo, Waldemar A A; Schmidt, Oliver G; Mosca, Dante Homero

    2012-11-21

    Compact rolled-up Co-Cu nanomembranes of high quality with different numbers of windings are realized by strain engineering. A profound analysis of magnetoresistance (MR) is performed for tubes with a single winding and a varied number of Co-Cu bilayers in the stack. Rolled-up nanomembranes with up to 12 Co-Cu bilayers are successfully fabricated by tailoring the strain state of the Cr bottom layer. By carrying out an angular dependent study, we ruled out the contribution from anisotropic MR and confirm that rolled-up Co-Cu multilayers exhibit giant magnetoresistance (GMR). No significant difference of MR is found for a single wound tube compared with planar devices. In contrast, MR in tubes with multiple windings is increased at low deposition rates of the Cr bottom layer, whereas the effect is not observable at higher rates, suggesting that interface roughness plays an important role in determining the GMR effect of the rolled-up nanomembranes. Furthermore, besides a linear increase of the MR with the number of windings, the self-rolling of nanomembranes substantially reduces the device footprint area.

  15. Nanoscale characterization and magnetic property of NiCoCu/Cu multilayer nanowires

    NASA Astrophysics Data System (ADS)

    Qi, Kuo; Li, Xinghua; Zhang, Hong; Wang, Li; Xue, Desheng; Zhang, Haoli; Zhou, Baofan; Mellors, Nigel J.; Peng, Yong

    2012-12-01

    NiCo/Cu multilayer nanowires have been successfully fabricated by a pulse electrodeposition technique using anodic aluminum oxide templates, and their chemistry, crystal structure and magnetic properties characterized at the nanoscale. It was found that each individual nanowire had a regular periodic structure. The NiCo/Cu nanowires also displayed a continuous morphology, smooth surface and polycrystalline fcc structure. EDX elemental mappings confirmed the presence of nickel, cobalt and copper, which appear clearly with a periodic distribution throughout the samples. Both the NiCo and Cu layers were polycrystalline and the average length of the interlayers between NiCo and Cu layers was approximately 3-4 nm. The NiCo/Cu nanowire arrays had an easy axis parallel to the length of wire and exhibited a curling magnetization reversal mechanism. This study highlights the basis morphological, structural and chemical information for NiCoCu/Cu multilayer nanowires, which is critical for their applications in nanodevices and nanoelectronics.

  16. Nanoscale characterization and magnetic property of NiCoCu/Cu multilayer nanowires.

    PubMed

    Qi, Kuo; Li, Xinghua; Zhang, Hong; Wang, Li; Xue, Desheng; Zhang, Haoli; Zhou, Baofan; Mellors, Nigel J; Peng, Yong

    2012-12-21

    NiCo/Cu multilayer nanowires have been successfully fabricated by a pulse electrodeposition technique using anodic aluminum oxide templates, and their chemistry, crystal structure and magnetic properties characterized at the nanoscale. It was found that each individual nanowire had a regular periodic structure. The NiCo/Cu nanowires also displayed a continuous morphology, smooth surface and polycrystalline fcc structure. EDX elemental mappings confirmed the presence of nickel, cobalt and copper, which appear clearly with a periodic distribution throughout the samples. Both the NiCo and Cu layers were polycrystalline and the average length of the interlayers between NiCo and Cu layers was approximately 3-4 nm. The NiCo/Cu nanowire arrays had an easy axis parallel to the length of wire and exhibited a curling magnetization reversal mechanism. This study highlights the basis morphological, structural and chemical information for NiCoCu/Cu multilayer nanowires, which is critical for their applications in nanodevices and nanoelectronics.

  17. Chemical stability of highly (0001) textured Sm(CoCu){sub 5} thin films with a thin Ta capping layer

    SciTech Connect

    Zhao Haibao; Wang Hao; Liu Xiaoqi; Wang Jianping; Zhang Tao

    2011-04-01

    With the highest magnetocrystalline anisotropy constant (Ku) among practical magnetic materials, SmCo{sub 5} could be a very attractive candidate for future high areal density magnetic recording. However, its corrosion resistance is always a concern in recording media applications. In this paper, the chemical stability and microstructures of highly (0001) textured Sm(CoCu){sub 5} thin films with and without a 3 nm Ta capping layer were reported. For Sm(CoCu){sub 5} thin films without a capping layer, the coercivity decreases significantly (from 8kOe to 1kOe) within one month. Sm(CoCu){sub 5} thin films capped with a thin Ta layer (3 nm) behave differently. Even exposed to a laboratory environment (25 deg. C) over 3 years, the Ta-capped Sm(CoCu){sub 5} thin films are stable in terms of structural and magnetic properties, i.e., there were no changes in X-ray diffraction peaks and vibrating sample magnetometer hysteresis loops. Microstructure of Ta-capped Sm(CoCu){sub 5} thin films showed that Sm(CoCu){sub 5} formed a domelike particle assembly structure on a smooth Ru underlayer and were well covered by partially oxidized Ta capping layer, as shown by TEM cross-section micrographs. Accelerated corrosion treatment (130 deg. C, 95% relative humidity, 6 h) was performed on Ta-capped Sm(CoCu){sub 5} thin films. X-ray photoelectron spectroscopy (XPS) results showed that no Co was detected on the sample surface before the corrosion treatment, but strong XPS signals of CoOx and Co(OH)x were observed after treatment. Therefore, none of our Sm(CoCu){sub 5} thin films can pass the accelerated corrosion test. Hcp-phased CoPt-alloys are proposed as better capping materials for Sm(CoCu){sub 5} thin films in future high-density magnetic recording applications.

  18. CMR of Co/Cu multilayers with reduced hysteresis and low-field response

    SciTech Connect

    Mao, M.; Gibbons, M.; Law, B.; Grabner, F.; Veron, S.; Cerjan, C.

    1997-02-01

    We present the results of a systematic study on optimization of the giant magnetoresistance (GMR) response in Co/Cu multilayers (MLs) for copper layer thickness near the second oscillatory peak. Co/Cu MLs with alternating thick (t(1)Co) and thin (t(2)Co) layers have been prepared in the from of [Cot(1)CoA/Cu20A/Cot(2)CoA/Cu20A]15. We have found that the magnetoresistive hysteresis of these MLs is reduced with decreasing t(2)Co and has disappeared when t(2)Co<4.5A. We have obtained an optimal GMR response with a field sensitivity of 0. 013%/Oe over a field region of -60 Oe centered at -50 Oe. This architecture may enable the use of Cu/Co MLs in low-field magnetic sensor applications.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Mansell, R.; Petit, D. C. M. C.; Fernández-Pacheco, A.; Lavrijsen, R.; Lee, J. H.; Cowburn, R. P.

    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.

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

    SciTech Connect

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

    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.

  2. Saturation magnetization in supersaturated solid solution of Co-Cu alloy

    NASA Astrophysics Data System (ADS)

    Yuasa, Motohiro; Kajikawa, Kota; Hakamada, Masataka; Mabuchi, Mamoru

    2009-10-01

    The magnetovolume effect has been investigated using a supersaturated solid solution of a Co-19 at. %Cu alloy processed by electrodeposition. The enhanced saturation magnetization of the Co-Cu alloy was attributed to both metastable fcc Co and lattice expansion. The density functional theory using the CASTEP code revealed that an enhanced magnetic moment due to the magnetovolume effect is obtained in fcc Co, but not in hcp Co.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Influence of the Electrodeposition Potential on the Co-Cu Alloys Thin Films Properties

    NASA Astrophysics Data System (ADS)

    Mentar, L.; Khelladi, M. R.; Beniaiche, A.; Azizi, A.

    2013-12-01

    Co-Cu alloy thin films were electrodeposited on a fluorine-doped tin oxide (FTO)-coated conducting glass substrate from a sulfate solution at applied potentials ranging from -0.7 V to -1.3 V versus saturated calomel electrode (SCE). Voltammetric studies showed that the composition and, consequently, the potential dissolution of Co depend greatly on the applied potentials. The compositional measurement, which was made using an atomic absorption spectroscopy (AAS), demonstrated that the Co content of the films considerably increases as the applied potentials to tend toward negative values. The SEM study showed that a granular structure of the electrodeposited Co-Cu. X-ray diffraction measurements showed that all peaks of the Co-Cu films were consistent with those of a typical Co hcp and Co-fcc mixed phase and Cu-fcc phase at low potential. The increase of the applied potential induces a decrease in the grain size and the lattice constant. The magnetic hysteresis measurements carried out by an alternating gradient force magnetometer (AGFM) revealed the existence of a ferromagnetic behavior with an in-plane easy magnetization axis for the film deposited at -1.1 V versus SCE. However, for applied potentials of -1.2 V and -1.3 V, we observe the coexistence of a dominant in-plane easy magnetization along with a perpendicular one.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2016-05-23

    The effect of biquadratic coupling on spin current induced magnetization switching in a Co/Cu/Ni-Fe nanopillar device is investigated by solving the free layer magnetization switching dynamics governed by the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. The LLGS equation is numerically solved by using Runge-Kutta fourth order procedure for an applied current density of 5 × 10{sup 12} Am{sup -2}. Presence of biquadratic coupling in the ferromagnetic layers reduces the magnetization switching time of the nanopillar device from 61 ps to 49 ps.

  7. Sonochemical preparation of bimetallic Co/Cu nanoparticles in aqueous solution

    SciTech Connect

    Jia Yaoshun; Niu Helin; Wu Mingzai; Ning Min; Zhu Hongfei; Chen Qianwang . E-mail: cqw@ustc.edu.cn

    2005-09-01

    Co/Cu bimetallic nanocrystallites, with average diameter of 50 nm, were prepared by a sonochemical method in the hydrazine solution of copper chloride and cobalt chloride. Cobalt was face-centered cubic phase when synthesized and remained fcc phase throughout the annealing process. X-ray diffractometer (XRD), transmission electron microscope (TEM), differential scanning calorimetry (DSC), vibrating sample magnetometry (VSM), inductively coupled plasma-atomic emission spectrometer (ICP-AES) measurements were carried out to investigate their structural and magnetic properties. It was found that the magnetic properties of bimetallic nanocrystallites were close to that of the sputtered alloys.

  8. Electrical determination of relative chirality direction in a Co/Cu/Co ferromagnetic ring

    NASA Astrophysics Data System (ADS)

    Demiray, A. S.; Kohda, M.; Miyawaki, T.; Watanabe, Y.; Saito, K.; Mitani, S.; Takanashi, K.; Nitta, J.

    2012-08-01

    We have studied a Co/Cu/Co trilayer circular ring by using a current-in-plane giant magnetoresistance (GMR) method. When the applied field angle is shifted from the current probes, four distinctive magnetization reversal patterns are obtained depending on the vortex chirality configurations in the top and bottom rings. During the repeated GMR measurements, two GMR patterns are preferentially appeared and it turns out that the same chirality is favorable between the top and the bottom rings. Micromagnetic simulation reproduces the experimental data by taking into account the domain wall shift at the onion states.

  9. Double quantum well states in Cu/Co/Cu grown on Co(001)

    NASA Astrophysics Data System (ADS)

    Ling, W. L.; Rotenberg, Eli; Choi, H. J.; Wolfe, J. H.; Toyama, F.; Paik, Silena; Smith, N. V.; Qiu, Z. Q.

    2002-03-01

    A double quantum well (QW) system of Cu/Co(1 ML)/Cu grown on Co/Cu(001) has been investigated by photoemission spectroscopy. Energy spectra of the valence band from one of the Cu QW's have been measured as a function of the other Cu QW thickness. The results show strong resonance between the two Cu QW states across a 1 ML Co barrier. In particular, we observe that quantum well coupling removes the degeneracy of the two Cu QW states, resulting in a state crossing effect. A phase accumulation model is developed to explain these observations.

  10. Checkerboard pattern of the interlayer coupling between two Co films across Fe/Cu and Cu/Co/Cu spacer layers grown on Cu(100)

    NASA Astrophysics Data System (ADS)

    Wu, Y. Z.; Won, C. Y.; Rotenberg, E.; Zhao, H. W.; Smith, N. V.; Qiu, Z. Q.

    2004-06-01

    Quantum well (QW) states and oscillatory interlayer coupling in Co/Cu/Fe/Co/Cu ( 001 ) are investigated by angular resolved photoemission spectroscopy and x-ray magnetic linear dichroism. We find that the QW states in Cu/Fe/Co/Cu ( 001 ) depend very little on the magnetic state of the fcc Fe films. The interlayer coupling between the Co films across the Cu/Fe spacer layer displays a checkerboard pattern in Fe-Cu thickness plane. The presence of the fcc Fe ferromagnetic live layer at the Cu/Fe interface is shown to be responsible for the checkerboard pattern, which was confirmed by experiments on Co/Cu/Co/Cu/Co/Cu ( 100 ) system.

  11. [CoCuMnOx Photocatalyzed Oxidation of Multi-component VOCs and Kinetic Analysis].

    PubMed

    Meng, Hai-long; Bo, Long-li; Liu, Jia-dong; Gao, Bo; Feng, Qi-qi; Tan, Na; Xie, Shuai

    2016-05-15

    Solar energy absorption coating CoCuMnOx was prepared by co-precipitation method and applied to photodegrade multi- component VOCs including toluene, ethyl acetate and acetone under visible light irradiation. The photocatalytic oxidation performance of toluene, ethyl acetate and acetone was analyzed and reaction kinetics of VOCs were investigated synchronously. The research indicated that removal rates of single-component toluene, ethyl acetate and acetone were 57%, 62% and 58% respectively under conditions of 400 mg · m⁻³ initial concentration, 120 mm illumination distance, 1 g/350 cm² dosage of CoCuMnOx and 6 h of irradiation time by 100 W tungsten halogen lamp. Due to the competition among different VOCs, removal efficiencies in three-component mixture were reduced by 5%-26% as compared with single VOC. Degradation processes of single-component VOC and three-component VOCs both fitted pseudo first order reaction kinetics, and kinetic constants of toluene, ethyl acetate and acetone were 0.002, 0.002 8 and 0.002 33 min⁻¹ respectively under single-component condition. Reaction rates of VOCs in three-component mixture were 0.49-0.88 times of single components.

  12. GMR of Co/Cu multilayers with reduced hysteresis and low-field response

    SciTech Connect

    Mao, M.; Gibbons, M.; Law, B.; Grabner, F.; Vernon, S.P.; Cerjan, C.

    1997-09-01

    The authors present the results of a systematic study on optimization of the giant magnetoresistance (GMR) response in Co/Cu multilayers (MLs) for Cu layer thickness near the second oscillatory peak. Co/Cu MLs with alternating thick (t{sub Co}{sup (1)}) and thin (t{sub Co}{sup (2)}) Co layers have been prepared in the form of [Cot{sub Co}{sup (1)}{angstrom}/Cu20{angstrom}/Cot{sub Co}{sup (2)}{angstrom}/Cu20{angstrom}]{sub 15}. They have found that the magnetoresistive hysteresis of these MLs is reduced with decreasing t{sub Co}{sup (2)} and has disappeared when t{sub Co}{sup (2)} < 4.5 {angstrom}. They have obtained an optimal GMR response with a field sensitivity of 0.13%/Oe over a field region of {approximately}60 Oe centered at {approximately}50 Oe. This architecture may enable the use of Cu/Co MLs in low-field magnetic sensor applications.

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

    PubMed

    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.

  14. Effect of alloy formation processes in the Co-Cu system on the magnetic and magnetoresistance properties of multilayer Co/Cu films with ultrathin Co layers prepared by DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Khalyapin, D. L.; Kim, P. D.; Kim, J.; Turpanov, I. A.; Beten'kova, A. Ya.; Bondarenko, G. V.; Isaeva, T. N.; Kim, I.

    2010-09-01

    This paper reports on a study of multilayer Co/Cu films with an effective thickness of the Co layer of ˜3.5 Å, which were prepared by magnetron sputtering. The samples prepared have been found to have a metastable multiphase structure. An analysis of the data obtained by structural and, primarily, by magnetic methods has revealed that the main phases are the Co/Cu supersaturated solid solution (alloy) with a Co concentration of about 30 at %, the superparamagnetic phase, and the paramagnetic phase, which is accounted for by the presence of small (a few atoms at most) Co clusters embedded in the Cu matrix. A clearly pronounced maximum in the temperature dependences of the low-field magnetoresistance has been found, which is associated with the temperature of the magnetic phase transition of the supersaturated Co-Cu alloy.

  15. In situ measurement of stress in Co/Cu, Co/Pd, and Co/Au compositionally modulated multilayer films

    NASA Astrophysics Data System (ADS)

    Awano, H.; Suzuki, Y.; Katayama, T.; Itoh, A.

    1990-11-01

    Temporal changes of sign and magnitude of the intrinsic stress during ultra-high vacuum deposition of Co/Cu, Co/Pd, and Co/Au compositionally modulated multilayer films (CMF's) were investigated by means of a cantilever technique. The intrinsic stress corresponding to monatomic layers could be detected during deposition. The intrinsic stress in Co layers deposited on Cu, Pd, and Au layers is tensile and the stress of Cu, Pd, and Au layers on Co is compressive. The intrinsic stress of a Co layer on Cu in Co/Cu CMF approaches near to the ideal critical shear stress of the perfect crystal, 1×1011 dyn/cm2.

  16. MCTDH study on vibrational states of the CO/Cu(100) system

    NASA Astrophysics Data System (ADS)

    Meng, Qingyong; Meyer, Hans-Dieter

    2013-10-01

    Full (6D) and reduced (4D and 2D) dimensional multiconfiguration time-dependent Hartree (MCTDH) calculations for the vibrational fundamentals and overtones of the CO/Cu(100) system are carried out using the recently reported [R. Marquardt, F. Cuvelier, R. A. Olsen, E. J. Baerends, J. C. Tremblay, and P. Saalfrank, J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES). To efficiently perform MCTDH calculations with the Heidelberg package (http://mctdh.uni-hd.de), the SAP-PES is first refitted in a sum-of-products form. Then extensive MCTDH calculations are carefully performed including thorough convergence checks to ensure the accuracy of our results. Full dimensional improved-relaxations and/or block-improved-relaxations are then performed to obtain vibrational ground and excited states of CO/Cu(100). In addition, we investigate the frustrated rotation (R mode) and vertical CO-Cu stretch (S mode), as well as C-O stretch, using a 4D Hamiltonian, which includes the distance between CO and the surface, z, bond length of CO, r, and orientation angles of CO, θ, and ϕ. The complement of this 4D Hamiltonian, a 2D Hamiltonian including only x and y coordinates, is used to alternatively calculate the states of frustrated translation (T mode). The comparison of reduced- with full-dimensional results show that the couplings between the R or S mode and the T mode do not influence the fundamentals and overtones of the R and S modes, however, do considerably influence those of the T mode. For the fundamental of the T mode, the 6D calculation yields an energy of 25.09 cm-1, a value closer to the experimental result of 31.8 cm-1 [A. P. Graham, F. Hofmann, J. P. Toennies, G. P. Williams, C. J. Hirschmugl, and J. Ellis, J. Chem. Phys. 108, 7825-7834 (1998)] than previously reported 19.6 cm-1 [R. Marquardt, F. Cuvelier, R. A. Olsen, E. J. Baerends, J. C. Tremblay, and P. Saalfrank, J. Chem. Phys. 132, 074108 (2010)] although both investigations are based on the SAP

  17. Electronic aspect and giant magnetoresistance in Co/Cu/Co sandwich structures

    NASA Astrophysics Data System (ADS)

    Diao, Z. T.; Tsunashima, S.; Jimbo, M.; Iwata, S.

    1996-07-01

    We have studied the electronic states in a non-magnetic spacer layer of Co/Cu/Co sandwich layers using the magneto-optical Kerr effect (MOKE) and x-ray photoemission and have found that they are discrete owing to the quantum size effect and appear approximately every 0953-8984/8/27/007/img7. This coincides with the oscillation period of the saturation field. We connect them with the quantum minority-spin interface states near the Fermi level 0953-8984/8/27/007/img8. The magnetoresistance found in these sandwich layers has been calculated on the basis of the quantum size effect transport theory with the requirement that there exist quantum well states within individual layers or groups of layers. The results of the calculation and experiments have been discussed.

  18. Domain wall pinning in FeCoCu bamboo-like nanowires

    PubMed Central

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

    2016-01-01

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

  19. Body centered cubic buffer layers for enhanced lateral grain growth of Co/Cu multilayers

    NASA Astrophysics Data System (ADS)

    Tsunoda, Masakiyo; Takahashi, Daisuke; Takahashi, Migaku

    2003-05-01

    The effect of buffer layers (BLs) on metallurgical microstructure and giant magnetoresistance of Co/Cu multilayers fabricated on them is discussed. The lateral grain size and the magnetoresistance (MR) ratio of multilayers are generally enlarged with changing the chemical composition of BLs toward a limiting concentration, within the range where the solid solution of body-centered-cubic (bcc) structure is formed. A guiding principle for material research for the BLs, which realize flat interfaces with large lateral grain size in the multilayers, is deduced from the correlation between the MR ratio of the multilayers and the surface energy of bcc BLs: the difference between the surface energy of BL (γS) and the interfacial energy (γSL) in Young-Dupré's equation (cos θ=(γS-γSL)/γL) should agree with the surface energy of Co layer (γL), which is deposited first on the BL.

  20. Microstructural and magnetic properties of CoCu nanoparticles prepared by wet chemistry.

    PubMed

    García, Ignacio; Pomposo, José A; Echeberria, Jon; Ollo, Jaione; Ilyn, Maxim; Guslienko, Konstantin Y; González, Julián M

    2010-07-01

    Co(10)Cu(90) nanopowder alloys have been prepared by the sonochemical wet method. In this way, Cu/Co bimetallic nanocrystallites with average diameter of 10-20 nm, presenting a homogeneous metastable solid solution of Co in Cu, were produced. Their structural characterization by X-ray diffraction, transmission electron microscopy and inductive coupled plasma-atomic emission spectrometry techniques has been used. Temperature dependences of the sample magnetization show two characteristic (blocking) temperatures associated to the typical deviation of the zero-field cooling and field-cooling magnetization curves at T1 approximately 15 and T2 approximately 310 K, respectively. This effect can be attributed to the fact that the samples consist of either superparamagnetic and/or ferromagnetic nanoparticles of different sizes. The samples were annealed at 300 degrees C and 450 degrees C and the observed evolution of their magnetic properties was explained in relation to decomposition of the metastable Co/Cu solid solution.

  1. Magnetic stripe domains of [Pt/Co/Cu]{sub 10} multilayer near spin reorientation transition

    SciTech Connect

    Sun, L.; Liang, J. H.; Xiao, X.; Zhou, C.; Huo, Y.; Wu, Y. Z.; Chen, G.

    2016-05-15

    The dependence of magnetic anisotropy, magnetic domain patterns and magnetization reversal processes in [Pt/Co(t{sub Co})/Cu]{sub 10} film stack epitaxied on Cu (111) substrate have been studied as a function of the Co layer thickness t{sub Co}, by magneto-optic polar Kerr magnetometry and microscopy. We find the film undergoes spin reorientation transition from out-of-plane to in-plane as t{sub Co} increases. The SRT thickness is verified by Rotating-field Magneto-Optic Kerr effect method. The film exhibits the stripe domain structures at remanence with the width decreasing while t{sub Co} approaches SRT. As demonstrated by the first order reversal curve measurement, the magnetization reversal process encompasses irreversible domain nucleation, domain annihilation at large field and reversible domain switching near remanence.

  2. Domain wall pinning in FeCoCu bamboo-like nanowires

    NASA Astrophysics Data System (ADS)

    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.

  3. Dispersion of quantum well states in Cu/Co/Cu(001)

    NASA Astrophysics Data System (ADS)

    Wu, Y. Z.; Won, C. Y.; Rotenberg, E.; Zhao, H. W.; Toyoma, F.; Smith, N. V.; Qiu, Z. Q.

    2002-12-01

    Quantum well states (QWS’s) in Cu thin films grown on Co/Cu(001) were studied using angle-resolved photoemission spectroscopy. For the normal photoemission, QWS’s from both lower and higher energy bands relative to the vacuum level were measured, and explained by phase accumulation method. QWS’s from the lower band were studied in detail as a function of the in-plane momentum k∥. We found that the QWS dispersion depends on the Cu film thickness. From the experimental data, we deduced the quantized perpendicular momentum k⊥ and the energy as a function of k∥. Our results show that the in-plane effective mass can not be obtained by a simple parabolic fitting of the E vs k∥ due to the dependence of k⊥ on k∥.

  4. Magnetic stripe domains of [Pt/Co/Cu]10 multilayer near spin reorientation transition

    NASA Astrophysics Data System (ADS)

    Sun, L.; Liang, J. H.; Xiao, X.; Zhou, C.; Chen, G.; Huo, Y.; Wu, Y. Z.

    2016-05-01

    The dependence of magnetic anisotropy, magnetic domain patterns and magnetization reversal processes in [Pt/Co(tCo)/Cu]10 film stack epitaxied on Cu (111) substrate have been studied as a function of the Co layer thickness tCo, by magneto-optic polar Kerr magnetometry and microscopy. We find the film undergoes spin reorientation transition from out-of-plane to in-plane as tCo increases. The SRT thickness is verified by Rotating-field Magneto-Optic Kerr effect method. The film exhibits the stripe domain structures at remanence with the width decreasing while tCo approaches SRT. As demonstrated by the first order reversal curve measurement, the magnetization reversal process encompasses irreversible domain nucleation, domain annihilation at large field and reversible domain switching near remanence.

  5. Large morphological sensitivity of the magneto-thermopower in Co/Cu multilayered systems

    NASA Astrophysics Data System (ADS)

    Popescu, Voicu; Kratzer, Peter

    2015-03-01

    We present results of first-principles calculations on the transport properties, both under an electric field or a temperature gradient, in Co/Cu multilayered systems. The various effects brought about by the changes in the morphological parameters, such as the number of repeats and the layer thickness, are discussed in a systematic way. Our calculations show that the Seebeck coefficient and the magneto-thermopower (MTP) converge rather rapidly with the number of Co repeats. In the range of thin Co layers, we find strong variations in the amplitude and sign of both the Seebeck coefficient and the MTP. These large variations, which have no correspondent in the (magneto)conductance, are shown to be the result of quantum well states present in the minority spin channel of thin Co layers.

  6. Co-Cu-Au deposits in metasedimentary rocks-A preliminary report

    USGS Publications Warehouse

    Slack, J.F.; Causey, J.D.; Eppinger, R.G.; Gray, J.E.; Johnson, C.A.; Lund, K.I.; Schulz, K.J.

    2010-01-01

    A compilation of data on global Co-Cu-Au deposits in metasedimentary rocks refines previous descriptive models for their occurrence and provides important information for mineral resource assessments and exploration programs. This compilation forms the basis for a new classification of such deposits, which is speculative at this early stage of research. As defined herein, the Co-Cu-Au deposits contain 0.1 percent or more by weight of Co in ore or mineralized rock, comprising disseminated to semi-massive Co-bearing sulfide minerals with associated Fe- and Cu-bearing sulfides, and local gold, concentrated predominantly within rift-related, siliciclastic metasedimentary rocks of Proterozoic age. Some deposits have appreciable Ag ? Bi ? W ? Ni ? Y ? rare earth elements ? U. Deposit geometry includes stratabound and stratiform layers, lenses, and veins, and (or) discordant veins and breccias. The geometry of most deposits is controlled by stratigraphic layering, folds, axial-plane cleavage, shear zones, breccias, or faults. Ore minerals are mainly cobaltite, skutterudite, glaucodot, and chalcopyrite, with minor gold, arsenopyrite, pyrite, pyrrhotite, bismuthinite, and bismuth; some deposits have appreciable tetrahedrite, uraninite, monazite, allanite, xenotime, apatite, scheelite, or molybdenite. Magnetite can be abundant in breccias, veins, or stratabound lenses within ore or surrounding country rocks. Common gangue minerals include quartz, biotite, muscovite, K-feldspar, albite, chlorite, and scapolite; many deposits contain minor to major amounts of tourmaline. Altered wall rocks generally have abundant biotite or albite. Mesoproterozoic metasedimentary successions constitute the predominant geologic setting. Felsic and (or) mafic plutons are spatially associated with many deposits and at some localities may be contemporaneous with, and involved in, ore formation. Geoenvironmental data for the Blackbird mining district in central Idaho indicate that weathering of

  7. Dealloying NiCo and NiCoCu Alloy Thin Films Using Linear Sweep Voltammetry

    NASA Astrophysics Data System (ADS)

    Peecher, Benjamin; Hampton, Jennifer

    When electrodeposited into thin films, metals have well-known electrochemical potentials at which they will be removed from the film. These potential differences can be utilized to re-oxidize only certain metals in an alloy, altering the film's structure and composition. Here we discuss NiCo and NiCoCu thin films' response to linear sweep voltammetry (LSV) as a means of electrochemical dealloying. For each of four different metal ratios, films were dealloyed to various potentials in order to gain insight into the evolution of the film over the course of the LSV. Capacitance, topography, and composition were examined for each sample before and after linear sweep voltammetry was performed. For NiCo films with high percentages of Ni, dealloying resulted in almost no change in composition, but did result in an increased capacitance, with greater increases occurring at higher LSV potentials. Dealloying also resulted in the appearance of large (100-1000 nm) pores on the surface of the film. For NiCoCu films with high percentages of Ni, Cu was almost completely removed from the film at LSV potentials greater than 500 mV. The LSV first removed larger copper-rich dendrites from the film's surface before creating numerous nano-pores, resulting in a net increase in area. This work is supported by an Award to Hope College from the HHMI Undergraduate Science Education Program, the Hope College Department of Physics Frissel Research Fund, and the National Science Foundation under Grants RUI-DMR-1104725 and MRI-CHE-0959282.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. State Crossing in Cu/Co/Cu(100) Double Quantum Well System

    NASA Astrophysics Data System (ADS)

    Ling, W. L.; Choi, H. J.; Wolfe, J. H.; Toyama, F.; Paik, S.; Qiu, Z. Q.; Rotenberg, E.; Smith, N. V.

    2001-03-01

    It has been shown that oscillatory magnetic interlayer coupling between two ferromagnetic layers across a non-magnetic spacer layer comes from the Quantum Well (QW) states in the spacer layer. While most works have been focused on single QW systems, little is known about the interaction between quantum wells in a heterostructure. We here report the results of our study on a double QW system. Two Cu QWs, separated by 1ML Co, were grown on Co/Cu(100) and investigated by photoemission at the Advanced Light Source (ALS) of Lawrence Berkeley Nat. Lab. (LBNL). Energy spectra of the valence band from one Cu QW were measured as a function of the other Cu QW thickness. The results show that these two Cu QWs are strongly coupled through the 1ML Co. Moreover, we observed that whenever the QW states of the two individual Cu layer reach the same energy level, the coupling of the two QWs generates a crossing from states v to states v+1. Phase accumulation model was developed to explain this state crossing effect.

  10. Magnetooptical, optical, and magnetotransport properties of Co/Cu superlattices with ultrathin cobalt layers

    NASA Astrophysics Data System (ADS)

    Lobov, I. D.; Kirillova, M. M.; Makhnev, A. A.; Romashev, L. N.; Korolev, A. V.; Milyaev, M. A.; Proglyado, V. V.; Bannikova, N. S.; Ustinov, V. V.

    2017-01-01

    We investigated the field dependences of the magnetization and magnetoresistance of superlattices [Co( t x, Å)/Cu(9.6 Å)]30 prepared by magnetron sputtering, differing in the thickness of cobalt layers (0.3 Å ≤ t Co ≤ 15 Å). The optical and magnetooptical properties of these objects were studied by ellipsometry in the spectral region of hω= 0.09-6.2 eV and with the help of the transverse Kerr effect ( hω= 0.5-6.2 eV). In the curves of an off-diagonal component of the tensor of the optical conductivity of superlattices with t Co = 3-15 Å, a structure of oscillatory type ("loop") was detected in the ultraviolet region, resulting from the exchange splitting of the 3d band in the energy spectrum of the face-centered cubic structure of cobalt ( fcc Co). Based on magnetic experiments and measurements of the transverse Kerr effect, we found the presence of a superparamagnetic phase in Co/Cu superlattices with a thickness of the cobalt layers of 3 and 2 Å. The transition from superlattices with solid ferromagnetic layers to superparamagnetic cluster-layered nanostructures and further to the structures based on Co and Cu ( t Co = 0.3-1 Å) with a Kondo-like characteristics of the electrical resistivity at low temperatures is analyzed.

  11. Magnetic behaviour of multisegmented FeCoCu/Cu electrodeposited nanowires

    NASA Astrophysics Data System (ADS)

    Núñez, A.; Pérez, L.; Abuín, M.; Araujo, J. P.; Proenca, M. P.

    2017-04-01

    Understanding the magnetic behaviour of multisegmented nanowires (NWs) is a major key for the application of such structures in future devices. In this work, magnetic/non-magnetic arrays of FeCoCu/Cu multilayered NWs electrodeposited in nanoporous alumina templates are studied. Contrarily to most reports on multilayered NWs, the magnetic layer thickness was kept constant (30 nm) and only the non-magnetic layer thickness was changed (0 to 80 nm). This allowed us to tune the interwire and intrawire interactions between the magnetic layers in the NW array creating a three-dimensional (3D) magnetic system without the need to change the template characteristics. Magnetic hysteresis loops, measured with the applied field parallel and perpendicular to the NWs’ long axis, showed the effect of the non-magnetic Cu layer on the overall magnetic properties of the NW arrays. In particular, introducing Cu layers along the magnetic NW axis creates domain wall nucleation sites that facilitate the magnetization reversal of the wires, as seen by the decrease in the parallel coercivity and the reduction of the perpendicular saturation field. By further increasing the Cu layer thickness, the interactions between the magnetic segments, both along the NW axis and of neighbouring NWs, decrease, thus rising again the parallel coercivity and the perpendicular saturation field. This work shows how one can easily tune the parallel and perpendicular magnetic properties of a 3D magnetic layer system by adjusting the non-magnetic layer thickness.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Magnetohydrodynamic Modeling and Experimental Validation of Convection Inside Electromagnetically Levitated Co-Cu Droplets

    NASA Astrophysics Data System (ADS)

    Lee, Jonghyun; Matson, Douglas M.; Binder, Sven; Kolbe, Matthias; Herlach, Dieter; Hyers, Robert W.

    2014-06-01

    A magnetohydrodynamic model of internal convection of a molten Co-Cu droplet processed by the ground-based electromagnetic levitation (EML) was developed. For the calculation of the electromagnetic field generated by the copper coils, the simplified Maxwell's equations were solved. The calculated Lorentz force per volume was used as a momentum source in the Navier-Stokes equations, which were solved by using a commercial computational fluid dynamics package. The RNG k- ɛ model was adopted for the prediction of turbulent flow. For the validation of the developed model, a Co16Cu84 sample was tested using the EML facility in the German Aerospace Center, Cologne, Germany. The sample was subjected to a full melt cycle, during which the surface of the sample was captured by a high-speed camera. With a sufficient undercooling, the liquid phase separation occurred and the Co-rich liquid phase particles could be observed as they were floating on the surface along streamlines. The convection velocity was estimated by the combination of the displacement of the Co-rich particles and the temporal resolution of the high-speed camera. Both the numerical and experimental results showed an excellent agreement in the convection velocity on the surface.

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

    SciTech Connect

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

    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}.

  15. High REE and Y concentrations in Co-Cu-Au ores of the Blackbird district, Idaho

    USGS Publications Warehouse

    Slack, J.F.

    2006-01-01

    Analysis of 11 samples of strata-bound Co-Cu-Au ore from the Blackbird district in Idaho shows previously unknown high concentrations of rare earth elements (REE) and Y, averaging 0.53 wt percent ???REE + Y oxides. Scanning electron microscopy indicates REE and Y residence in monazite, xenotime, and allanite that form complex intergrowths with cobaltite, suggesting coeval Co and REE + Y mineralization during the Mesoproterozoic. Occurrence of high REE and Y concentrations in the Blackbird ores, together with previously documented saline-rich fluid inclusions and Cl-rich biotite, suggest that these are not volcanogenic massive sulfide or sedimentary exhalative deposits but instead are iron oxide-copper-gold (IOCG) deposits. Other strata-bound Co deposits of Proterozoic age in the North American Cordillera and elsewhere in the world may have potential for REE and Y resources. IOCG deposits with abundant light REE should also be evaluated for possible unrecognized heavy REE and Y mineralization. ?? 2006 by Economic Geology.

  16. Tilted CO on metal surfaces; CO/Pt(110), CO/Ni(110) and CO/Cu(100)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.

    1985-01-01

    Tilting of CO at coverages greater than half a monolayer is considered as a mechanism for reducing the CO-CO repulsion. Qualitative agreement with the experiment for CO/Pt(110) is found, and a slightly smaller tilt for CO/Ni(110) is predicted. For CO/Cu(100), it is found that a bend of about 10 deg greatly reduces the repulsion.

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

    SciTech Connect

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

    2011-12-31

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

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

    PubMed

    Özkale, Berna; Shamsudhin, Naveen; Chatzipirpiridis, George; Hoop, Marcus; Gramm, Fabian; Chen, Xiangzhong; Martí, Xavi; Sort, Jordi; Pellicer, Eva; Pané, Salvador

    2015-04-08

    In this paper, we report on the synthesis of FeCo/Cu multisegmented nanowires by means of pulse electrodeposition in nanoporous anodic aluminum oxide arrays supported on silicon chips. By adjustment of the electrodeposition conditions, such as the pulse scheme and the electrolyte, alternating segments of Cu and ferromagnetic FeCo alloy can be fabricated. The segments can be built with a wide range of lengths (15-150 nm) and exhibit a close-to-pure composition (Cu or FeCo alloy) as suggested by energy-dispersive X-ray mapping results. The morphology and the crystallographic structure of different nanowire configurations have been assessed thoroughly, concluding that Fe, Co, and Cu form solid solution. Magnetic characterization using vibrating sample magnetometry and magnetic force microscopy reveals that by introduction of nonmagnetic Cu segments within the nanowire architecture, the magnetic easy axis can be modified and the reduced remanence can be tuned to the desired values. The experimental results are in agreement with the provided simulations. Furthermore, the influence of nanowire magnetic architecture on the magnetically triggered protein desorption is evaluated for three types of nanowires: Cu, FeCo, and multisegmented FeCo15nm/Cu15nm. The application of an external magnetic field can be used to enhance the release of proteins on demand. For fully magnetic FeCo nanowires the applied oscillating field increased protein release by 83%, whereas this was found to be 45% for multisegmented FeCo15nm/Cu15nm nanowires. Our work suggests that a combination of arrays of nanowires with different magnetic configurations could be used to generate complex substance concentration gradients or control delivery of multiple drugs and macromolecules.

  19. Descriptive and geoenvironmental model for Co-Cu-Au deposits in metasedimentary rocks: Chapter G in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Slack, John F.; Johnson, Craig A.; Causey, J. Douglas; Lund, Karen; Schulz, Klaus J.; Gray, John E.; Eppinger, Robert G.; Slack, John F.

    2013-01-01

    Additional geologically and compositionally similar deposits are known, but have average Co grades less than 0.1 percent. Most of these deposits contain cobalt-rich pyrite and lack appreciable amounts of distinct Co sulfide and (or) sulfarsenide minerals. Such deposits are not discussed in detail in the following sections, but these deposits may be revelant to the descriptive and genetic models presented below. Examples include the Scadding Au-Co-Cu deposit in Ontario, Canada; the Vähäjoki Co-Cu-Au deposit in Finland; the Tuolugou Co-Au deposit in Qinghai Province, China; the Lala Co-Cu-UREE deposit in Sichuan Province, China; the Guelb Moghrein Cu-Au-Co deposit in Mauritania; and the Great Australia Co-Cu, Greenmount Cu-Au-Co, and Monakoff Cu-Au-Co-UAg deposits in Queensland, Australia. Detailed information on these deposits is presented in appendix 2.

  20. FeMn/Fe/Co/Cu(1,1,10) films studied using the magneto-optic Kerr effect and photoemission electron microscopy

    SciTech Connect

    Meng, Y.; Li, J.; Tan, A.; Park, J.; Jin, E.; Son, H.; Doran, A.; Scholl, A.; Arenholz, E.; Zhao, H. W.; Hwang, Chanyong; Qiu, Z. Q.

    2011-07-31

    FeMn/Fe/Co/Cu(1,1,10) films were grown epitaxially and investigated using the magneto-optic Kerr effect and photoemission electron microscopy. We found that FeMn/Fe/Co/Cu(1,1,10) exhibits the same properties as FeMn/Co/Cu(1,1,10) for the ferromagnetic phase of the face centered cubic (fcc) Fe film but a different property for the non-ferromagnetic phase of the fcc Fe film. This result indicates that the characteristic property reported in the literature for FeMn/Co/Cu(001) comes from the FeMn spin structure and is independent of the ferromagnetic layer.

  1. Microstructure study of pinning sites of highly (0001) textured Sm(Co,Cu){sub 5} thin films grown on Ru underlayer

    SciTech Connect

    Zhao Haibao; Wang Hao; Liu Xiaoqi; Wang Jianping

    2012-04-01

    In this paper, microstructure study of pinning sites of highly (0001) textured Sm(Co,Cu){sub 5} thin films was presented. Various types of pinning sites were identified, such as voids, grain/matrix boundaries (or crystalline/amorphous boundaries), grain boundaries between crystalline grains, and composition inhomogeneity in grains. One key finding of TEM elemental mapping was that Cu atoms were rich in the inner part of Sm(Co,Cu){sub 5} grains (defined by Sm and Co concentrations), instead of the outer part of grains, such as grain boundaries. Cu served as an alloying element in Sm(Co,Cu){sub 5} grains, not as a doping element to form Cu-rich grain boundaries. A model of Sm(Co,Cu){sub 5} films with lateral graded anisotropy due to composition/crystallization variation can explain the huge difference between the H{sub C} and H{sub K}.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Determination of the magnetic coupling in the Co/Cu/Co(100) system with momentum-resolved quantum well states

    SciTech Connect

    Kawakami, R.K.; Rotenberg, E.; Escorcia-Aparicio, E.J.; Choi, Hyuk J.; Wolfe, J.H.; Smith, N.V.; Qiu, Z.Q.

    1999-05-17

    The relation between the quantum well (QW) states and the oscillatory magnetic coupling in Co/Cu/Co grown on Cu(100) was investigated by angle-resolved photoemission spectroscopy, magnetic x-ray linear dichroism, and the surface magneto-optic Kerr effect. The QW states were explained quantitatively using the phase accumulation model, and the derived QW phases at the Cu/Co interface were used to calculate the interlayer coupling. The agreement between this calculation and the experimental result reveals that the phase relation between the long- and short-period couplings is determined by the phase relation of the QW states in k-space.

  4. Solid-solution CrCoCuFeNi high-entropy alloy thin films synthesized by sputter deposition

    DOE PAGES

    An, Zhinan; Jia, Haoling; Wu, Yueying; ...

    2015-05-04

    The concept of high configurational entropy requires that the high-entropy alloys (HEAs) yield single-phase solid solutions. However, phase separations are quite common in bulk HEAs. A five-element alloy, CrCoCuFeNi, was deposited via radio frequency magnetron sputtering and confirmed to be a single-phase solid solution through the high-energy synchrotron X-ray diffraction, energy-dispersive spectroscopy, wavelength-dispersive spectroscopy, and transmission electron microscopy. The formation of the solid-solution phase is presumed to be due to the high cooling rate of the sputter-deposition process.

  5. Inter- and intra-nanowire magnetic interaction in Co/Cu multilayer nanowires deposited by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Xi, Hongbo; Gao, Youhui; Liu, Zhong; Han, Gang; Lu, Jiadao; Li, Yongliang

    2017-08-01

    Intra- and inter-wire magnetic interactions in Co/Cu multilayer nanowire arrays have been studied with the Henkel plot method. It has been found that the intra-nanowire interaction greatly decreases with an increase in the Cu spacer thickness. Magnetoresistance of 0.16% has been obtained in Co(200 nm)/Cu(5 nm)/Co(10 nm) junction. However, the magnetoresistance effect is negligible both in the juctions with strong intra-nanowire interaction (thickness of Cu spacer is less than 3 nm) and the juctions with strong current-depolarization (thickness of Cu spacer is more than 17 nm).

  6. Correlation of remanence and giant magnetoresistance data in sputtered Co/Cu and Fe/Cu multilayers (abstract)

    NASA Astrophysics Data System (ADS)

    Parker, M. R.; Seale, D.; Tsang, E.; Barnard, J. A.; Hossain, S.; Richards, D. A.; Watson, M. L.

    1993-05-01

    It is well established that magnetic interactions in particulate media and films can be assessed on the basis of the correlation between the normalized dc demagnetization remanence, Id(H), and the normalized isothermal remagnetization remanence, Ir(H). Departures of Henkel plots from the straight-line relationship of the Wohlfarth equation may be regarded as a measure of the strength of the intergranular field interactions in thin films. Delta-I plots are commonly used to manifest these interactions. These remanence techniques have been applied to both ordered and highly disordered (granular) sputtered multilayers of Co/Cu in which the giant magnetoresistance effect has been observed. Both the Henkel plots and the delta-I (MR) plots exhibit oscillatory characteristics, which correlate with magnetoresistance and critical field data. Figure 1 shows the amplitude of the delta-I plot as a function of Cu volume fraction in quasigranular Co/Cu films in good correlation with the amplitude of the giant MR effect. Similar results have been obtained even with relatively thick multilayers of Fe/Cu in which the giant MR is extremely weak. These results would seem to indicate that comprehensive remanence measurements involving Henkel and/or delta-I plots are effective in evaluating intergranular exchange coupling in giant MR film systems, given that these plots can be processed to provide quantitative interaction field data.

  7. Determination of the Magnetic Coupling in the Co/Cu/Co(100) System with Momentum-Resolved Quantum Well States

    SciTech Connect

    Kawakami, R.K.; Escorcia-Aparicio, E.J.; Choi, H.J.; Wolfe, J.H.; Qiu, Z.Q.; Rotenberg, E.; Smith, N.V.

    1999-05-01

    The relation between the quantum well (QW) states and the oscillatory magnetic coupling in Co/Cu/Co grown on Cu(100) was investigated by angle resolved photoemission spectroscopy, magnetic x-ray linear dichroism, and the surface magneto-optic Kerr effect. The QW states were explained quantitatively using the phase accumulation model, and the derived QW phases at the Cu/Co interface were used to calculate the interlayer coupling. The agreement between this calculation and the experimental result reveals that the phase relation between the long- and short-period couplings is determined by the phase relation of the QW states in k space. {copyright} {ital 1999} {ital The American Physical Society}

  8. Picosecond time-resolved adsorbate response to substrate heating: Spectroscopy and dynamics of CO/Cu(100)

    NASA Astrophysics Data System (ADS)

    Germer, T. A.; Stephenson, J. C.; Heilweil, E. J.; Cavanagh, R. R.

    1994-07-01

    The response of the molecular stretch mode of CO/Cu(100) near 2086 cm-1 (ν1) to resonant infrared, and nonresonant visible and ultraviolet pumping is measured on a picosecond time scale. Fourier transform infrared measurements establish that ν1 is anharmonically coupled to the frustrated translation near 32 cm-1 (ν4), so that transient shifts in ν1 indicate population changes in ν4. The ν1 response to visible and ultraviolet pumping is characterized by a spectral shift near zero delay time, which decays with a ≊2 ps time constant to an intermediate value, which then decays on a ≊200 ps time scale. The data agree well with a model whereby ν4 couples to both the photogenerated hot electrons and to the heated phonons. The characteristic coupling times to these two heat baths are found to both be a few picoseconds.

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

    SciTech Connect

    Savitha Pillai, S.; Kojima, H.; Itoh, M.; Taniyama, T.

    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.

  10. Engineering of the anisotropy and Dzyaloshinskii-Moriya interaction energies in Pt-Co and Pt-Co-Cu heterostructures

    NASA Astrophysics Data System (ADS)

    Schlotter, Sarah; Beach, Geoffrey

    It has previously been shown that perpendicular magnetic anisotropy is increased in Pt-Co-Pt structures by placing a Cu spacer between the top, diffuse Co-Pt interface. However, including a spacer layer increases interfacial asymmetry in the system: a prerequisite for a strong Dzyaloshinskii-Moriya interaction (DMI) which governs helical spin structures such as skyrmions and chiral domain walls. We show that the increased asymmetry significantly enhances DMI strength in Pt-Co-Cu-Pt heterostructures as compared to corresponding Pt-Co-Pt systems. We further show that one can control the characteristic length scales governing domain width by engineering the magnetostatic, anisotropy, and DMI energies in heavy-metal/ferromagnet heterostructures. These structures may provide insight into engineering the size of skyrmions in spintronic devices.

  11. Local structure investigation of (Co, Cu) co-doped ZnO nanocrystals and its correlation with magnetic properties

    NASA Astrophysics Data System (ADS)

    Tiwari, N.; Doke, S.; Lohar, A.; Mahamuni, Shailaja; Kamal, C.; Chakrabarti, Aparna; Choudhary, R. J.; Mondal, P.; Jha, S. N.; Bhattacharyya, D.

    2016-03-01

    Pure, Co doped and (Co, Cu) co-doped ZnO nanocrystals have been prepared by wet chemical route at room temperature to investigate the effect of Cu doping in Co doped ZnO nanocrystals . The nanocrystals have initially been characterized by X-ray diffraction, FTIR, Raman, optical absorption and EPR spectroscopy and the results were corroborated with DFT based electronic structure calculations. Magnetic properties of the samples have been investigated by studying their magnetic hysteresis behavior and temperature dependence of susceptibilities. Finally the local structure at the host and dopant sites of the nanocrystals have been investigated by Zn, Co and Cu K edges EXAFS measurements with synchrotron radiation to explain their experimentally observed magnetic properties.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Geologic history of the Blackbird Co-Cu district in the Lemhi subbasin of the Belt-Purcell Basin

    USGS Publications Warehouse

    Bookstrom, Arthur A.; Box, Stephen E.; Cossette, Pamela M.; Frost, Thomas P.; Gillerman, Virginia; King, George; Zirakparvar, N. Alex

    2016-01-01

    The Blackbird cobalt-copper (Co-Cu) district in the Salmon River Mountains of east-central Idaho occupies the central part of the Idaho cobalt belt—a northwest-elongate, 55-km-long belt of Co-Cu occurrences, hosted in grayish siliciclastic metasedimentary strata of the Lemhi subbasin (of the Mesoproterozoic Belt-Purcell Basin). The Blackbird district contains at least eight stratabound ore zones and many discordant lodes, mostly in the upper part of the banded siltite unit of the Apple Creek Formation of Yellow Lake, which generally consists of interbedded siltite and argillite. In the Blackbird mine area, argillite beds in six stratigraphic intervals are altered to biotitite containing over 75 vol% of greenish hydrothermal biotite, which is preferentially mineralized.Past production and currently estimated resources of the Blackbird district total ~17 Mt of ore, averaging 0.74% Co, 1.4% Cu, and 1.0 ppm Au (not including downdip projections of ore zones that are open downward). A compilation of relative-age relationships and isotopic age determinations indicates that most cobalt mineralization occurred in Mesoproterozoic time, whereas most copper mineralization occurred in Cretaceous time.Mesoproterozoic cobaltite mineralization accompanied and followed dynamothermal metamorphism and bimodal plutonism during the Middle Mesoproterozoic East Kootenay orogeny (ca. 1379–1325 Ma), and also accompanied Grenvilleage (Late Mesoproterozoic) thermal metamorphism (ca. 1200–1000 Ma). Stratabound cobaltite-biotite ore zones typically contain cobaltite1 in a matrix of biotitite ± tourmaline ± minor xenotime (ca. 1370–1320 Ma) ± minor chalcopyrite ± sparse allanite ± sparse microscopic native gold in cobaltite. Such cobaltite-biotite lodes are locally folded into tight F2 folds with axial-planar S2 cleavage and schistosity. Discordant replacement-style lodes of cobaltite2-biotite ore ± xenotime2 (ca. 1320–1270 Ma) commonly follow S2fractures and fabrics

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

    NASA Astrophysics Data System (ADS)

    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

  15. Field dependent resonance frequency of hysteresis loops in a few monolayer thick Co/Cu(001) films

    NASA Astrophysics Data System (ADS)

    Jiang, Q.; Yang, H.-N.; Wang, G.-C.

    1996-04-01

    Dynamic responses of magnetic hysteresis loops in a few monolayer (ML) thick Co/Cu(001) films were studied using surface magneto-optic Kerr effect (SMOKE). For a fixed external field strength H0, the hysteresis loop area increases as a function of frequency with a power law and reaches a maximum at a resonance frequency Ω0. This Ω0 depends on the external periodic field strength as well as the thickness and roughness of the films. The thickness and roughness parameters were measured quantitatively using high-resolution low-energy electron diffraction. For a fixed film thickness, the Ω0 in the low field region is highly dependent on H0, which is consistent with the prediction from the mean field model. For two Co films with an equivalent thickness but different degrees of film roughness, the resonance frequency Ω0 is lower for the rougher films in all the field strengths studied. For a fixed field strength, the value of Ω0 decreases as Co film roughness increases in a few ML regime. The roughness dependency in Ω0 indicates that the slowing down in the magnetization reversal process is due to the increased film roughness.

  16. Microstructure and giant magnetoresistance of Co-Cu granular films fabricated under the extremely clean sputtering process

    NASA Astrophysics Data System (ADS)

    Tsunoda, Masakiyo; Okuyama, Kentaro; Ooba, Makoto; Takahashi, Migaku

    1998-06-01

    In order to clarify the influence of the impurities in the sputtering atmosphere on the microstructure and the giant magnetoresistance (GMR) properties of nanogranular thin films, Co-Cu alloy films were prepared on quartz substrates at room temperature under the different purity of the sputtering atmosphere by changing the base pressure, 10-11 Torr extremely clean process (XC) and 10-7 Torr lower grade process (LG). The correlation between the microstructure and the GMR of films after an annealing procedure is discussed. As results, we found that; (1) A Co-rich phase combined with oxygen was formed at grain boundary in the films as deposited under the LG process; (2) the gradual progress of the grain growth of precipitates with increasing annealing temperature was observed in the XC-processed films, while the coarse grain growth of the matrix phase, resulting in the abrupt change of magnetoresistance occurred in the LG-processed films. We conclude that regulated impurity concentration in the films is an essential parameter to control the precipitation process from the supersaturated solid solution and to realize the desirable microstructure of the nanogranular GMR thin films.

  17. Determination of Co, Cu, Fe, Mn, Ni and V in diesel and biodiesel samples by ETV-ICP-MST.

    PubMed

    Chaves, Eduardo S; Lepri, Fábio G; Silva, Jessee S A; de Quadros, Daiane P C; Saint'Pierre, Tatiana D; Curtius, Adilson J

    2008-10-01

    This work presents the determination of Co, Cu, Fe, Mn, Ni and V in diesel and biodiesel samples by ETV-ICP MS using emulsion sample preparation. The emulsion composition was: 1.0 g of the diesel or biodiesel sample, 2.0 mL of a 5% m/v Triton X-100 solution, 0.5 mL of HNO3 and deionized water to a 10 mL final volume. The optimized parameters were mass of carrier/modifier (1.0 microg Pd), RF power (1100 W), carrier gas flow rate (0.95 L min(-1)) and inner ETV gas flow rate (0.15 L min(-1)). The determinations were performed against aqueous solutions using 10 microg L(-1) Rh as internal standard. The accuracy of the method was verified through the analysis of the NIST 1634c reference residual fuel oil, recovery tests and comparison of the results with those obtained by GF AAS. The results were in agreement according to the t-test at a 95% confidence level. The RSD values were lower than 20%, the recoveries were between 80 and 120% and the LOD values were in the order of ng g(-1), showing the good accuracy and sensitivity of the method.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Structure and giant magnetoresistance of granular Co-Cu nanolayers prepared by cross-beam pulsed laser deposition

    SciTech Connect

    Jesche, A.; Stoecker, H.; Levin, A. A.; Meyer, D. C.; Gorbunoff, A.; Mensch, A.

    2010-01-15

    A series of Co{sub x}Cu{sub 100-x} (x=0, 40-75, 100) layers with thicknesses between 13 and 55 nm were prepared on silicon substrates using cross-beam pulsed laser deposition. Wide-angle x-ray diffraction (WAXRD), transmission electron microscopy (TEM), and electrical transport measurements revealed a structure consisting of decomposed cobalt and copper grains with grain sizes of about 10 nm. The influence of cobalt content and layer thickness on the grain size is discussed. Electron diffraction indicates the presence of an intermetallic Co-Cu phase of Cu{sub 3}Au structure type. Thermal treatment at temperatures between 525 and 750 K results in the progressive decomposition of Co and Cu, with an increase of the grain sizes up to about 100 nm. This is tunable by controlling the temperature and duration of the anneal, and is directly observable in WAXRD patterns and TEM images. A careful analysis of grain size and the coherence length of the radiation used allows for an accurate interpretation of the x-ray diffraction patterns, by taking into account coherent and noncoherent scattering. The alloy films show a giant magnetoresistance of 1%-2.3% with the maximum obtained after annealing at around 725 K.

  20. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: The effect of substrate on magnetic properties of Co/Cu multilayer nanowire arrays

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Meng, Qingyong; Meyer, Hans-Dieter

    2015-10-01

    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.

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

    SciTech Connect

    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.

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

    PubMed

    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.

  4. Laser-produced spectra and QED effects for Fe-, Co-, Cu-, and Zn-like ions of Au, Pb, Bi, Th, and U

    NASA Technical Reports Server (NTRS)

    Seely, J. F.; Ekberg, J. O.; Brown, C. M.; Feldman, U.; Behring, W. E.

    1986-01-01

    Spectra of very highly charged ions of Au, Pb, Bi, Th, and U have been observed in laser-produced plasmas generated by the OMEGA laser. Line identifications in the region 9-110 A were made for ions in the Fe, Co, Cu, and Zn isoelectronic sequences. Comparison of the measured wavelengths of the Cu-like ions with values calculated with and without QED corrections shows that the inclusion of QED corrections greatly improves the accuracy of the calculated 4s-4p wavelengths. However, significant differences between the observed and calculated values remain.

  5. Investigation of cellular microstructure and enhanced coercivity in sputtered Sm{sub 2}(CoCuFeZr){sub 17} film

    SciTech Connect

    Bhatt, Ranu Schütz, G.; Bhatt, Pramod

    2014-03-14

    We have investigated the effect of annealing temperature on the microstructure and magnetic properties of Sm{sub 2}(CoCuFeZr){sub 17} films prepared using ion beam sputtering at room temperature. The as-deposited film shows randomly oriented polycrystalline grains and exhibits small coercivity (H{sub C}) of 0.04 T at room temperature. Post annealing of these films at 700 °C under Ar atmosphere shows significant changes in the microstructure transforming it to the development of cellular growth, concomitant with enhanced coercivity up to 1.3 T. The enhanced coercivity is explained using the domain wall pinning mechanism.

  6. Laser-produced spectra and QED effects for Fe-, Co-, Cu-, and Zn-like ions of Au, Pb, Bi, Th, and U

    NASA Technical Reports Server (NTRS)

    Seely, J. F.; Ekberg, J. O.; Brown, C. M.; Feldman, U.; Behring, W. E.

    1986-01-01

    Spectra of very highly charged ions of Au, Pb, Bi, Th, and U have been observed in laser-produced plasmas generated by the OMEGA laser. Line identifications in the region 9-110 A were made for ions in the Fe, Co, Cu, and Zn isoelectronic sequences. Comparison of the measured wavelengths of the Cu-like ions with values calculated with and without QED corrections shows that the inclusion of QED corrections greatly improves the accuracy of the calculated 4s-4p wavelengths. However, significant differences between the observed and calculated values remain.

  7. Non-free-electron momentum- and thickness-dependent evolution of quantum well states in the Cu/Co/Cu (001) system

    NASA Astrophysics Data System (ADS)

    Rotenberg, Eli; Wu, Y. Z.; An, J. M.; van Hove, M. A.; Canning, A.; Wang, L. W.; Qiu, Z. Q.

    2006-02-01

    We present systematic k‖ -dependent measurements of the Fermi surface and underlying band structure of quantum well states in Cu/Co/Cu(001) . Compared to bands from normal emission, we find a complicated evolution of “split” quantum well states as a function of the thicknesses of both the copper overlayer and the cobalt barrier layer. Self-consistent calculations show that the penetration of the quantum well states into the cobalt barrier layer is significant and leads to the observed very non-free-electron behavior of these states.

  8. Effect of Grain size on the Giant Intrinsic Coercivity of High-Energy Milled Sm(Co,Cu,Fe)5 Alloys

    NASA Astrophysics Data System (ADS)

    Sultana, Dilara; Gabay, Alexandar; Hadjipanayis, George

    2008-03-01

    The giant intrinsic magnetic hardness of Sm(Co,Cu)5 alloys have been known for a long time [1]. Previous studies suggested that this behavior is due to the crystal site disorder [2]. Our previous work has explained that the room-temperature intrinsic coercivity of 37 kOe after low-temperature aging is rather due to the intrinsic change in the Co atomic site occupation [3]. In this study, we investigated the effect of grain refinement through the high energy milling on the intrinsic coercivity of the Sm(Co,Cu,Fe)5 alloys. We have found that grain refinement does not affect the high coercivity of homogenized alloys, but strongly influences the onset of the giant coercivity during low-temperature aging. The microstructures of the samples are examined with TEM. [1] E.A. Nesbitt, R.H. Willens, R.C. Sherwood, E. Buehler, J.H. Wernick 1968 Appl.. Phys. Lett. 12, 361. [2] H. Oesterrier , F.T. Parker, M. Misroach 1979 J. Appl. Phys. 50, 4273. [3] A.M. Gabay, P. Larson, I.I. Manzin, G.C. Hadjipanayis 2005, J. Phys. D: Appl. Phys. 38, 1.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Microstructures and tribological properties of plasma sprayed WC-Co-Cu-BaF 2/CaF 2 self-lubricating wear resistant coatings

    NASA Astrophysics Data System (ADS)

    Yuan, Jianhui; Zhu, Yingchun; Ji, Heng; Zheng, Xuebing; Ruan, Qichao; Niu, Yaran; Liu, Ziwei; Zeng, Yi

    2010-06-01

    A promising WC-Co-Cu-BaF 2/CaF 2 self-lubricating wear resistant coating was deposited via atmospheric plasma spraying (APS) process by using homemade feedstock powders composed of WC-Co, Cu and BaF 2/CaF 2 eutectic. The as-prepared cermet coatings had better frictional behavior comparing with the WC-Co coating. Moreover, the often-occurred decarburization of WC in APS process was noticeably improved due to the binding of copper and BaF 2/CaF 2 phase, which not only offered effective solid lubrication, but also acted as bind phases to mend the microstructure and protected WC from decomposition. The optimized specimen contained 10 wt.% Cu and 10 wt.% BaF 2/CaF 2 in a WC-Co matrix, which had excellent frictional and wear performance. The wear mechanism of the self-lubricating wear resistant coating was discussed with the microstructures, compositions and mechanical properties of the composite materials in detail.

  11. Effect of aluminum on fine structure and distribution of chemical elements in high-entropy alloys Al x FeNiCoCuCr

    NASA Astrophysics Data System (ADS)

    Nadutov, V. M.; Makarenko, S. Yu.; Volosevich, P. Yu.

    2015-05-01

    Electron-microscopic and X-ray diffraction methods have been used to study the fine structure of cast high-entropy alloys (HEAs) Al x FeNiCoCuCr ( x = 1, 1.5, 1.8). Disperse precipitates with dimensions of 130-400 and 10-20 nm have been revealed, the character of distribution of which, as well as the amounts, dimensions, and shapes, change with increasing aluminum content. In the equiatomic HEA, copper-containing particles with an fcc structure have been found; in the alloy with x = 1.8, particles of bcc Al4Cu9 dominate. It has been shown that the most uniform distribution over the matrix is characteristic of Co, unlike other elements, among which Cu and Cr are distributed in the alloy extremely nonuniformly and predominantly enter into the precipitated particles and into clusters in the interparticle spaces, respectively.

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

    PubMed

    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.

  13. Effects of annealing on the microstructure and magnetic property of the mechanically alloyed FeSiBAlNiM (M=Co, Cu, Ag) amorphous high entropy alloys

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoxia; Zhou, Xuan; Yu, Shuaishuai; Wei, Congcong; Xu, Jing; Wang, Yan

    2017-05-01

    The effects of annealing treatment on the microstructure, thermal stability, and magnetic properties of the mechanical alloyed FeSiBAlNiM (M=Co, Cu, Ag) amorphous high entropy alloys (HEAs) have been investigated in this project. The simple crystallization products in FeSiBAlNi amorphous HEAs with Co and Ag addition reveal the high phase stability during heating process. At high annealing treatment, the crystallized HEAs possess the good semi-hard magnetic property. It can conclude that crystallization products containing proper FeSi-rich and FeB-rich phases are beneficial to improve the magnetic property. Annealing near the exothermic peak temperature presents the best enhancing effect on the semi-hard magnetic property of FeSiBAlNiCo. It performs both large saturated magnetization and remanence ratio of 13.0 emu/g and near 45%, which exhibit 465% and 105% enhancement compared with as-milled state, respectively.

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

    PubMed

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

    2015-11-20

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

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

    PubMed

    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.

  16. 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.

    PubMed

    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.

  17. Depth Profile of Induced Magnetic Polarization in Cu Layers of Co/Cu(111) Metallic Superlattices by Resonant X-ray Magnetic Scattering at the Cu K Absorption Edge

    NASA Astrophysics Data System (ADS)

    Uegaki, Shin; Yoshida, Akihiro; Hosoito, Nobuyoshi

    2015-03-01

    We investigated induced spin polarization of 4p conduction electrons in Cu layers of antiferromagnetically (AFM) and ferromagnetically (FM) coupled Co/Cu(111) metallic superlattices by resonant X-ray magnetic scattering at the Cu K absorption edge. Magnetic reflectivity profiles of the two superlattices were measured in the magnetic saturation state with circularly polarized synchrotron radiation X-rays at 8985 eV. Depth profiles of the resonant magnetic scattering length of Cu, which corresponds to the induced spin polarization of Cu, were evaluated in the two Co/Cu superlattices by analyzing the observed magnetic reflectivity profiles. We demonstrated that the spin polarization induced in the Cu layer was distributed around the Co/Cu interfaces with an attenuation length of several Å in both AFM and FM coupled superlattices. The uniform component, which exists in Au layers of Fe/Au(001) superlattices, was not found in the depth distribution of induced magnetic polarization in the Cu layers of Co/Cu(111) superlattices.

  18. 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

    NASA Astrophysics Data System (ADS)

    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

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

    SciTech Connect

    Rodríguez-González, B.; Bran, C.; Warnatz, T.; Vazquez, M.; Rivas, J.

    2014-04-07

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

  20. 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

    NASA Astrophysics Data System (ADS)

    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

  1. 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.

    PubMed

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

    2017-02-22

    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  ⩽  [Formula: see text]  ⩽  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

  2. Evaluation of diffusive gradients in thin films technique (DGT) for measuring Al, Cd, Co, Cu, Mn, Ni, and Zn in Amazonian rivers.

    PubMed

    Yabuki, Lauren Nozomi Marques; Colaço, Camila Destro; Menegário, Amauri Antonio; Domingos, Roberto Naves; Kiang, Chang Hung; Pascoaloto, Domitila

    2014-02-01

    Studies concerning the lability and bioavailability of trace metals have played a prominent role in the search for contamination of water resources. This work describes the first application yet of the diffusive gradients in thin films technique (DGT) to the determination of the fraction of free plus labile metals in waters from the Amazon Basin. Due to the complexity of the use of DGT for samples with low ionic strength and high organic matter content (characteristic of Amazonian rivers), a new analytical procedure was developed. The method is based on the determinations of apparent diffusion coefficients (Dap) in the laboratory, by performing deployments in samples collected in the corresponding sites of study. The Dap thereby determined is then used for in situ measurements. The suitability of the proposed approach for determination of labile Al, Cd, Co, Cu, Mn, Ni, and Zn in the Amazon River and Rio Negro (English: Black River) was evaluated. Except for Co, Mn (in a deployment at Rio Negro), Ni and Zn (in a deployment at Amazon River), labile in situ measurements were lower or similar to dissolved concentrations, indicating suitability of the proposed approach.

  3. Heavy metals (Cd, Co, Cu, Ni, Pb, Fe, and Hg) content in four fish commonly consumed in Iran: risk assessment for the consumers.

    PubMed

    Hosseini, Mehdi; Nabavi, Seyed Mohammad Bagher; Nabavi, Seyedeh Narges; Pour, Nasrin Adami

    2015-05-01

    In this study, concentrations of Cd, Co, Cu, Ni, Pb, Fe, and Hg were determined in commercially valuable fish from Khuzestan shore, northwest of the Persian Gulf. It was also our intention to evaluate potential risks to human health associated with seafood consumption. The liver and skin showed higher metal concentrations than the muscle. The results showed that heavy metal concentrations in different food habitats increase in the following order: benthic omnivorous fish < zooplanktivore fish < phytoplanktivore fish < piscivore fish. Also, the comparison indicated that benthic species (Euryglossa orientalis, Otolithes ruber) were more contaminated than pelagic species (Liza abu and Psettodes erumei). Therefore, the concentration of heavy metals in edible part of fish species did not exceed the permissible limits proposed by Food and Agriculture Organization (FAO) (1983), WHO (1996), Regional Organization for the Protection of the Marine Environment (ROPME) (1999), and FAD (2001) which are suitable for human consumption, except for Ni and Cd in E. orientalis and Pb in O. ruber.

  4. Single magnetic domain precipitates of Fe/Co and Fe and Co in Cu matrix produced from (Fe-Co)/Cu metastable alloys

    NASA Astrophysics Data System (ADS)

    Nascimento, V. P.; Passamani, E. C.; Takeuchi, A. Y.; Larica, C.; Nunes, E.

    2001-01-01

    Structural and magnetic properties of nanocrystalline Fe2Co and (Fe2Co)0.30 Cu0.70 alloys prepared by high energy ball milling have been studied basically by x-ray, Mössbauer spectroscopy and magnetization measurements. For the Fe2Co alloy case, the Mössbauer measurements indicate that the sample with 160 hours of milling has two magnetic components with the same average hyperfine parameters: one magnetic crystalline component associated with the bcc Fe2Co phase and another component attributed to the small particles of the same bcc Fe2Co phase (SP-Fe2Co). (Fe2Co)0.30Cu0.70 alloys have been prepared by milling in two different ways: (1) starting from the mixture of Fe2Co milled alloy and pure Cu powders (sample I) and (2) milling of the elemental powder mixture of Fe, Co and Cu (sample II). The x-ray diffraction and bulk magnetization results of samples I and II indicate the formation of a (Fe2Co)0.30Cu0.70 supersaturated solid solution, with features of a ferromagnetic material and Tc at about (420+/-1) K. High temperature magnetization measurements of the (Fe/Co)Cu milled materials show particle precipitation effects. Heat treatment at 675 and 875 K of the final milled materials leads to different results: in the sample I case to the precipitation of single magnetic Fe/Co particles into the Cu matrix, and in the case of sample II the precipitation of single magnetic particles of Fe and of Co into the Cu matrix.

  5. Determination of Cd, Co, Cu, Mn, Ni, Pb, and Zn by Inductively Coupled Plasma Mass Spectroscopy or Flame Atomic Absorption Spectrometry after On-line Preconcentration and Solvent Extraction by Flow Injection System

    PubMed

    Bortoli; Gerotto; Marchiori; Mariconti; Palonta; Troncon

    1996-11-01

    The concentrations of Cd, Co, Cu, Mn, Ni, Pb, and Zn in natural and sea waters are too low to be directly determined with by flame atomic absorption spectrometry (FAAS) or graphite furnace atomic absorption spectrometry (GFAAS). Specific sample preparations are requested that make possible the determination of these analytes by preconcentration or extraction. These techniques are affected by severe problems of sample contamination. In this work Cd, Co, Cu, Mn, Ni, Pb, and Zn were determined by inductively coupled plasma mass spectroscopy (ICP-MS) or by atomic absorption spectrometry, in fresh and seawater samples, after on-line preconcentration and following solvent elution with a flow injection system. Bonded silica with octadecyl functional group C18, packed in a microcolumn of 100-μl capacity, was used to collect diethyldithiocarbamate complexes of the heavy metals in aqueous solutions. The metals are complexed with a chelating agent, adsorbed on the C18 column, and eluted with methanol directly in the flow injection system. The methanolic stream can be addressed to FAAS for direct determination of Cu, Ni, and Zn, or collected in a vial for successive analysis by GFAAS. The eluted samples can be also dried in a vacuum container and restored to a little volume with concentrated HNO3 and Milli-Q water for analysis by ICP-MS or GFAAS.

  6. Effect of plasma-chemical and thermal treatment in oxygen on the activity of Na3ZrM(PO4)3 phosphates (M = Zn, Co, Cu) in the transformation of butanol-2

    NASA Astrophysics Data System (ADS)

    Pylinina, A. I.; Povarova, E. I.; Mikhalenko, I. I.; Yagodovskaya, T. V.

    2013-06-01

    The catalytic properties of plasma-chemically and thermally treated triple zirconium orthophosphates Na3ZrM(PO4)3 (M = Zn, Co, Cu) in the transformation of butanol-2 are studied. X-ray photoelectron spectroscopy data indicate that the surface composition of the samples differs from the stoichiometry, especially in the case of M = Cu. The partial reduction of copper ions occurs during plasma-chemical treatment (PCT), while the amount of Cu on the surface of Na3ZrCu(PO4)3 diminishes. Treatment in an oxygen glow discharge results in a 3-8 times greater yield of the alcohol dehydrogenation product, methyl ethyl ketone. The energy of the alcohol's bonds with the surface is reduced and the dehydration active sites become fully inactivated. In contrast, thermal treatment (TT) results in an increase in the activity of Na3ZrM(PO4)3 in the dehydration of butanol-2.

  7. 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.

    PubMed

    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.

  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).

    PubMed

    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. Strata-bound Fe-Co-Cu-Au-Bi-Y-REE deposits of the Idaho Cobalt Belt: Multistage hydrothermal mineralization in a magmatic-related iron oxide copper-gold system

    USGS Publications Warehouse

    Slack, John F.

    2012-01-01

    Mineralogical and geochemical studies of strata-bound Fe-Co-Cu-Au-Bi-Y-rare-earth element (REE) deposits of the Idaho cobalt belt in east-central Idaho provide evidence of multistage epigenetic mineralization by magmatic-hydrothermal processes in an iron oxide copper-gold (IOCG) system. Deposits of the Idaho cobalt belt comprise three types: (1) strata-bound sulfide lenses in the Blackbird district, which are cobaltite and, less commonly, chalcopyrite rich with locally abundant gold, native bismuth, bismuthinite, xenotime, allanite, monazite, and the Be-rich silicate gadolinite-(Y), with sparse uraninite, stannite, and Bi tellurides, in a gangue of quartz, chlorite, biotite, muscovite, garnet, tourmaline, chloritoid, and/or siderite, with locally abundant fluorapatite or magnetite; (2) discordant tourmalinized breccias in the Blackbird district that in places have concentrations of cobaltite, chalcopyrite, gold, and xenotime; and (3) strata-bound magnetite-rich lenses in the Iron Creek area, which contain cobaltiferous pyrite and locally sparse chalcopyrite or xenotime. Most sulfide-rich deposits in the Blackbird district are enclosed by strata-bound lenses composed mainly of Cl-rich Fe biotite; some deposits have quartz-rich envelopes.Whole-rock analyses of 48 Co- and/or Cu-rich samples show high concentrations of Au (up to 26.8 ppm), Bi (up to 9.16 wt %), Y (up to 0.83 wt %), ∑REEs (up to 2.56 wt %), Ni (up to 6,780 ppm), and Be (up to 1,180 ppm), with locally elevated U (up to 124 ppm) and Sn (up to 133 ppm); Zn and Pb contents are uniformly low (≤821 and ≤61 ppm, respectively). Varimax factor analysis of bulk compositions of these samples reveals geochemically distinct element groupings that reflect statistical associations of monazite, allanite, and xenotime; biotite and gold; detrital minerals; chalcopyrite and sparse stannite; quartz; and cobaltite with sparse selenides and tellurides. Significantly, Cu is statistically separate from Co and As

  10. Layered Molecule-Based Magnets Formed by Decamethylmetallocenium Cations and Two-Dimensional Bimetallic Complexes [ MIIRu III(ox) 3] -( MII=;Mn, Fe, Co, Cu and Zn; ox=oxalate)

    NASA Astrophysics Data System (ADS)

    Coronado, Eugenio; Galán-Mascarós, José R.; Gómez-García, Carlos J.; Martínez-Agudo, José M.; Martínez-Ferrero, Eugenia; Waerenborgh, Joao C.; Almeida, Manuel

    2001-07-01

    A new series of hybrid organometallic-inorganic layered magnets with formula [ZIIICp*2] [MIIRuIII(ox)3] (ZIII=Co and Fe; MII=Mn, Fe, Co, Cu, and Zn; ox=oxalate: Cp*=pentamethylcyclopentadienyl) has been prepared. All of these compounds are isostructural to the previously reported [ZIIICp*2] [MIIMIII(ox)3] (MIII=Cr, Fe) series and crystallize in the monoclinic space group C2/m, as found by powder X-ray diffraction analysis. They are novel examples of magnetic materials formed by bimetallic oxalate-based extended layers separated by layers of organometallic cations. The magnetic properties of all these compounds have been investigated (ac and dc magnetic susceptibilities and field dependence of the isothermal magnetization at 2 K). In particular, it has been found that FeII and CoII derivatives behave as magnets with ordering temperatures of 12.8 and 2.8 K, respectively, while no long-range magnetic ordering has been detected down to 2 K in the MnII and CuII derivatives. The magnetic ordering in the FeII derivatives has been confirmed through Mössbauer spectroscopy. This technique has also made it possible to observe the spin polarization of the paramagnetic [FeCp*2]+ units caused by the internal magnetic field created by the bimetallic layers in the ordered state.

  11. Raman and infrared studies of La1-ySryMn1-xMxO3 ( M=Cr , Co, Cu, Zn, Sc or Ga): Oxygen disorder and local vibrational modes

    NASA Astrophysics Data System (ADS)

    Dubroka, A.; Humlíček, J.; Abrashev, M. V.; Popović, Z. V.; Sapiña, F.; Cantarero, A.

    2006-06-01

    We present results of our study of polarized Raman scattering and infrared reflectivity of rhombohedral ceramic La1-ySryMn1-xMxO3 manganites in the temperature range between 77 and 320K . In our samples, a part of the Mn atoms is substituted by M=Cr , Co, Cu, Zn, Sc, or Ga with x in the range 0-0.1. The hole concentration was kept at the optimal value of about 32% by tuning the Sr content y . We have monitored distortions of the oxygen sublattice by the presence of broad bands in the Raman spectra, the increase of dc resistivity extracted from the infrared reflectivity, and the change of the critical temperature of the ferromagnetic transition. Our results support the idea that these properties are mainly determined by the radius of the substituent ion, its electronic and magnetic structure playing only a minor role. Furthermore, the Raman spectra exhibit an additional Ag -like high frequency mode attributed to the local breathing vibration of oxygens surrounding the substituent ion. Its frequency and intensity strongly depend on the type of the substituent. In the Co-substituted sample, the mode anomalously softens when going from 300to77K . The frequency of the bulk A1g mode depends linearly on the angle of the rhombohedral distortion.

  12. Novel Pulse Electrodeposited Co Cu ZnO Nanowire/tube Catalysts for C1 C4 Alcohols and C2 C6 (Except C5) Hydrocarbons from CO and H2

    SciTech Connect

    Gupta, Mayank; Schwartz, Viviane; Overbury, Steven {Steve} H; More, Karren Leslie; Meyer III, Harry M; Spivey, James J

    2012-01-01

    Co Cu ZnO nanowire/tube catalysts were synthesized using pulse electrodeposition technique from a single aqueous electrolyte solution using a template synthesis technique. They were then tested as catalysts for the hydrogenation of CO to alcohols and higher hydrocarbons. Nanowires/ tubes were grown inside the pores of membranes using a three-step sequential deposition process. First, a low current of 6.9 mA/cm2 was applied for 300 ms for Cu deposition, then a high current density of 11.5 mA/cm2 for t ms (t = 500, 600, 750 ms) was applied for Co deposition, and finally no current was applied for 1200 ms so that the ions near the cathode replenish. The surface had a significantly different composition than the bulk. On the surface, there was more Co, less Cu, and more Zn. The catalyst showed the alcohol (C1 C4) selectivity of 20.9 %C at H2/CO = 3/1, GHSV = 16 000 scc/h gcat, temperature = 270 C, pressure = 15 bar, and time-onstream = 65 h.

  13. Novel Pulse Electrodeposited Co-Cu-Zn Nanowire/tubeCatalysts for C1-C4 Alcohols and C2 - C6 (except C5) Hydrocarbons from CO and H2

    SciTech Connect

    Gupta, Mayank; Schwartz, Viviane; Overbury, Steven {Steve} H; More, Karren Leslie; Spivey, James J

    2012-01-01

    Co-Cu-ZnO nanowire/tube catalysts were synthesized using pulse electrodeposition technique from a single aqueous electrolyte solution using a template synthesis technique. They were then tested as catalysts for the hydrogenation of CO to alcohols and higher hydrocarbons. Nanowires/tubes were grown inside the pores of membranes using a three-step sequential deposition process. First, a low current of -6.9 mA/cm{sup 2} was applied for 300 ms for Cu deposition, then a high current density of -11.5 mA/cm{sup 2} for t ms (t = 500, 600, 750 ms) was applied for Co deposition, and finally no current was applied for 1200 ms so that the ions near the cathode replenish. The surface had a significantly different composition than the bulk. On the surface, there was more Co, less Cu, and more Zn. The catalyst showed the alcohol (C{sub 1}-C{sub 4}) selectivity of 20.9 %C at H{sub 2}/CO = 3/1, GHSV = 16,000 scc/h gcat, temperature = 270 C, pressure = 15 bar, and time-on-stream = 65 h.

  14. Defect chemistry of La{sub 2}Ni{sub 1{minus}x}M{sub x}O{sub 4} (M = Mn, Fe, Co, Cu): Relevance to catalytic behavior

    SciTech Connect

    Read, M.S.D.; Islam, M.S.; King, F.; Hancock, F.E.

    1999-03-04

    Atomistic computer simulation techniques are used to investigate the defect properties of the La{sub 2}Ni{sub 1{minus}x}M{sub x}O{sub 4} (M = Mn, Fe, Co, Cu) layered perovskite which are related to the mode of operation of the catalyst. The theoretical techniques are based upon efficient energy minimization procedures and Mott-Littleton methodology for accurate defect modeling. Effective ionic pairwise interatomic potentials correctly reproduce the tetragonal crystal structure. The formation energy of intrinsic atomic defects of the Schottky and Frenkel type are not particularly favorable. The oxidation of La{sub 2}NiO{sub 4+{delta}} was found to be an exothermic process with charge compensation occurring via hole formation preferentially on the Ni site. The highest solubility, for a range of dopants, is calculated for Sr and Ca, in accord with observation. Hole formation was most favorable for Mn > Fe > Co > Ni(undoped) > Cu, demonstrating that Mn and Fe enhance Ni(III) hole formation, which is believed to be an important factor in the observed catalytic activity.

  15. Distribution of selected essential (Co, Cu, Fe, Mn, Mo, Se, and Zn) and nonessential (Cd, Pb) trace elements among protein fractions from hepatic cytosol of European chub (Squalius cephalus L.).

    PubMed

    Krasnići, Nesrete; Dragun, Zrinka; Erk, Marijana; Raspor, Biserka

    2013-04-01

    Association of selected essential (Co, Cu, Fe, Mn, Mo, Se, and Zn) and nonessential (Cd, Pb) trace elements with cytosolic proteins of different molecular masses was described for the liver of European chub (Squalius cephalus) from weakly contaminated Sutla River in Croatia. The principal aim was to establish basic trace element distributions among protein fractions characteristic for the fish living in the conditions of low metal exposure in the water. The fractionation of chub hepatic cytosols was carried out by size exclusion high performance liquid chromatography (SE-HPLC; Superdex™ 200 10/300 GL column), and measurements were performed by high resolution inductively coupled plasma mass spectrometry (HR ICP-MS). Elution profiles of essential elements were mostly characterized by broad peaks covering wide range of molecular masses, as a sign of incorporation of essential elements in various proteins within hepatic cytosol. Exceptions were Cu and Fe, with elution profiles characterized by sharp, narrow peaks indicating their probable association with specific proteins, metallothionein (MT), and ferritin, respectively. The main feature of the elution profile of nonessential metal Cd was also single sharp, narrow peak, coinciding with MT elution time, and indicating almost complete Cd detoxification by MT under the conditions of weak metal exposure in the water (dissolved Cd concentration ≤0.3 μg L(-1)). Contrary, nonessential metal Pb was observed to bind to wide spectrum of proteins, mostly of medium molecular masses (30-100 kDa), after exposure to dissolved Pb concentration of ~1 μg L(-1). The obtained information within this study presents the starting point for identification and characterization of specific metal/metalloid-binding proteins in chub hepatic cytosol, which could be further used as markers of metal/metalloid exposure or effect on fish.

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

    SciTech Connect

    Gordon, Ryan T.

    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.

  17. An ICP-MS procedure to determine Cd, Co, Cu, Ni, Pb and Zn in oceanic waters using in-line flow-injection with solid-phase extraction for preconcentration.

    PubMed

    O'Sullivan, Jeanette E; Watson, Roslyn J; Butler, Edward C V

    2013-10-15

    An automated procedure including both in-line preconcentration and multi-element determination by an inductively coupled plasma mass spectrometer (ICP-MS) has been developed for the determination of Cd, Co, Cu, Ni, Pb and Zn in open-ocean samples. The method relies on flow injection of the sample through a minicolumn of chelating (iminodiacetate) sorbent to preconcentrate the trace metals, while simultaneously eliminating the major cations and anions of seawater. The effectiveness of this step is tested and reliability in results are secured with a rigorous process of quality assurance comprising 36 calibration and reference samples in a run for analysis of 24 oceanic seawaters in a 6-h program. The in-line configuration and procedures presented minimise analyst operations and exposure to contamination. Seawater samples are used for calibration providing a true matrix match. The continuous automated pH measurement registers that chelation occurs within a selected narrow pH range and monitors the consistency of the entire analytical sequence. The eluent (0.8M HNO3) is sufficiently strong to elute the six metals in 39 s at a flow rate of 2.0 mL/min, while being compatible for prolonged use with the mass spectrometer. Throughput is one sample of 7 mL every 6 min. Detection limits were Co 3.2 pM, Ni 23 pM, Cu 46 pM, Zn 71 pM, Cd 2.7 pM and Pb 1.5 pM with coefficients of variation ranging from 3.4% to 8.6% (n=14) and linearity of calibration established beyond the observed concentration range of each trace metal in ocean waters. Recoveries were Co 96.7%, Ni 102%, Cu 102%, Zn 98.1%, Cd 92.2% and Pb 97.6%. The method has been used to analyse ~800 samples from three voyages in the Southern Ocean and Tasman Sea. It has the potential to be extended to other trace elements in ocean waters.

  18. 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

    USGS Publications Warehouse

    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

  19. 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

    NASA Astrophysics Data System (ADS)

    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

  20. Oxalate-based soluble 2D magnets: the series [K(18-crown-6)]3[M(II)3(H2O)4{M(III)(ox)3}3] (M(III) = Cr, Fe; M(II) = Mn, Fe, Ni, Co, Cu; ox = C2O4(2-); 18-crown-6 = C12H24O6).

    PubMed

    Coronado, Eugenio; Galán-Mascarós, José R; Martí-Gastaldo, Carlos; Waerenborgh, João C; Gaczyński, Piotr

    2008-08-04

    The synthesis and magnetic properties of the oxalate-based molecular soluble magnets with general formula [K(18-crown-6)] 3[M (II) 3(H 2O) 4{M (III)(ox) 3} 3] (M (III) = Cr, Fe; M (II) = Mn, Fe, Ni, Co, Cu; ox = C 2O 4 (2-)) are here described. All the reported compounds are isostructural and built up by 2D bimetallic networks formed by alternating M (III) and M (II) ions connected through oxalate anions. Whereas the Cr (III)M (II) derivatives behave as ferromagnets with critical temperatures up to 8 K, the Fe (III)M (II) present ferri- or weak ferromagnetic ordering up to 26 K.

  1. Magnetic properties of Co-Cu metastable solid solution alloys

    NASA Astrophysics Data System (ADS)

    Fan, Xu; Mashimo, Tsutomu; Huang, Xinsheng; Kagayama, Tomoko; Chiba, Akira; Koyama, Keiichi; Motokawa, Mitsuhiro

    2004-03-01

    Metastable solid solution alloy powders and bulk alloys in the cobalt(Co)-copper(Cu) (10 90 mol % Co) system, which is an almost immiscible system at the ambient state, were prepared by mechanical alloying (MA) and shock compression. All MA-treated powders showed the x-ray diffraction patterns of a single phase of fcc structure. The lattice parameter increases with Cu concentration and is fundamentally on the line with Vegard’s law. The magnetization curves of CoxCu100-x (x=20 80) metastable bulk alloys at room temperature showed ferromagnetism, while the one of Co10Cu90 system showed paramagnetism. The saturation magnetic moment (Ms) curve versus electron numbers per atom at 0 K was found to be similar to the Slater-Pauling curves of other transition-metal binary systems and decreased with increasing Cu concentration and approached zero at about 28.8 electrons per atom. The magnetoresistance ratio at room temperature increased with Cu content in the ferromagnetic region, while the one of the paramagnetic Co10Cu90 alloy was negligibly small.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. Materials Data on Co(CuO2)4 (SG:12) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2016-04-22

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Materials Data on Co(CuO2)4 (SG:2) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2016-04-22

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Materials Data on LiCoCuO4 (SG:2) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-04-22

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. -Interface effects on the magnetic moment of Co and Cu in CoCu granular alloys

    SciTech Connect

    Garcia Prieto, A.; Fdez-Gubieda, M.L.; Chaboy, J.; Laguna-Marco, M.A.; Muro, T.; Nakamura, T.

    2005-12-01

    We report on x-ray magnetic circular dichroism experiments performed on Co{sub 5}Cu{sub 95} annealed granular alloys with giant magnetoresistance. Results on the Co-L{sub 2,3} edge evidence a direct correlation between the Co orbital and spin magnetic moment and the Co clusters interfacial roughness. On the other hand, we have found dichroism on the Cu-L{sub 2,3} edge, revealing an induced magnetic polarization of the Cu interfacial atoms. The magnetic moment of the Cu atoms is mainly of spin character and is ferromagnetically coupled with the Co magnetic moment.

  7. Magnetic properties and giant magnetoresistance in melt-spun Co-Cu alloys

    NASA Astrophysics Data System (ADS)

    Yu, R. H.; Zhang, X. X.; Tejada, J.; Knobel, M.; Tiberto, P.; Allia, P.

    1995-07-01

    Magnetic, structural, and transport properties of as-quenched and annealed Co10Cu90 samples have been investigated using x-ray diffraction and a SQUID magnetometer. The largest value of MR change was observed for the as-quenched sample annealed at 450 °C for 30 min. The magnetic and transport properties closely correlate with the microstructure, mainly with Co magnetic particle size and its distribution. For thermal annealing the as-quenched samples below 600 °C, the Co particle diameters increase from 4.0 to 6.0 nm with a magnetoresistance (MR) drop from 33.0% to 5.0% at 10 K. Comparison with the theory indicates that the interfacial electron spin-dependent scattering mechanism correlates with GMR for Co particle diameters up to about 6.0 nm.

  8. Materials Data on CoCu2SnS4 (SG:121) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  9. Materials Data on CoCu2Sn (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  10. Materials Data on CoCu2SnSe4 (SG:121) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

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

    PubMed

    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

  12. Magnetic properties of Nd-Fe-Co(Cu)-Al-B amorphous alloys prepared by nonequilibrium techniques

    NASA Astrophysics Data System (ADS)

    Kumar, G.; Eckert, J.; Roth, S.; Löser, W.; Ram, S.; Schultz, L.

    2002-03-01

    The amorphous alloys Nd40Fe40Co5Al8B7, Nd57Fe20Co5Al10B8, and Nd57Fe20Cu5Al10B8 were prepared by copper mold casting, melt spinning, and mechanical alloying. Despite their similar x-ray diffraction patterns, samples display different magnetic and thermal behavior correlated with the method of preparation. The fully amorphous melt-spun ribbons exhibit relatively soft magnetic properties with coercivities ≈40 kA/m at room temperature and a Curie temperature (TC)≈474 K. Apparently only the mold-cast cylinders of 3 mm diameter show hard magnetic behavior with a coercivity in the range of 258-270 kA/m (depending on composition) and have approximately the same TC as that of the melt-spun ribbons. An additional magnetic transition at 585 K due to the presence of Nd2Fe14B phase in the case of Nd40Fe40Co5Al8B7 cast rod has been observed. Heat treatment above crystallization temperature in as-cast Nd57Fe20Co5Al10B8 and Nd57Fe20Cu5Al10B8 samples destroys the hard magnetic properties. In contrast, mechanically alloyed amorphous samples are soft magnetic with maximum coercivity up to 11 kA/m but show an entirely different TC≈680-740 K, which is rather characteristic of an Fe solid solution. The magnetic properties are discussed in terms of different local atomic environment and cluster sizes in amorphous samples prepared by different methods.

  13. Structure and magnetic properties of metastable Co-Cu solid solution nanowire arrays fabricated by electrodeposition

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Li, Fashen; Wang, Ying; Song, Lijing

    2006-08-01

    Nanowire arrays of the metastable Cox Cu1-x (0.20 x 0.85) solid solution system which can not be obtained by equilibrium methods, were prepared by electrodeposition in pores of anodic aluminum oxide (AAO) template, and subsequently annealed at different temperatures. The as-deposited samples all show single phase of fcc structure, and lattice parameters decrease with the increase of Co content and fundamentally accord with Vegard's law. The phase transition with heat treatment was investigated by X-ray diffraction and differential thermal analysis (DTA) which further confirmed the formation of solid solution. With Co content increasing, the coercivity along nanowire axis for as-deposited samples increases, but it decreases for the annealed samples at 700 °C. This phenomenon was explained considering the interaction of Co particles through Cu in nanowires after phase separation.

  14. Anomalous temperature dependence of coercivity in precipitation hardened Pr-Co-Cu-Ti magnets

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Liu, Hui; Rong, Chuan-bin; Zhang, Hong-wei; Zhang, Shao-ying; Shen, Bao-gen; Bai, Yuan-qiang; Li, Bao-he

    2003-08-01

    The anomalous temperature dependence of coercicity, Hc(T), has been observed in precipitation hardened PrCo6.7-xCuxTi0.3 (x=0.2-1) magnets. Transmission electron microscopy reveals that they exhibit a cellular microstructure. With an increase of Cu content, the Curie temperature of the 2:17 phase remains nearly unchanged whereas that of the 1:5 phase decreases. The peak of Hc(T) becomes higher, broader and shifts towards low temperature while the room temperature coercivity remains low and does not change with an increase of Cu content. There is a strong correlation between the Curie temperature of the 1:5 phase and the peak of Hc(T). The effect of Cu on Hc(T) cannot be explained by a traditional domain wall pinning model. It is highly likely that their magnetization reversal is controlled by the nucleation of reverse domains in isolated 2:17 cells.

  15. Simultaneous in-situ synthesis and characterization of Co@Cu core-shell nanoparticle arrays

    DOE PAGES

    McKeown, Joseph T.; Wu, Yueying; Fowlkes, Jason D.; ...

    2014-12-23

    Core-shell nanostructures have attracted much attention due to their unique and tunable properties relative to bulk structures of the same materials, making core-shell nanoparticles candidates for a variety of applications with multiple functionalities.[1,2] Intriguing magnetic behavior can be tailored by variation of size, interface, crystal orientation, and composition, and core-shell nanostructures with noble-metal shells yield novel optical responses[3] and enhanced electrocatalytic activity.[4

  16. Materials Data on Al7CoCu2 (SG:128) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-10

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Topology of spin meron pairs in coupled Ni/Fe/Co/Cu(001) disks

    NASA Astrophysics Data System (ADS)

    Tan, A.; Li, J.; Scholl, A.; Arenholz, E.; Young, A. T.; Li, Q.; Hwang, C.; Qiu, Z. Q.

    2016-07-01

    The meron is a special topological object that carries only one-half of the topological charge unit. In condensed matter physics, a spin meron corresponds to one-half of a spin skyrmion. As compared to the many fascinating topological properties of skyrmion materials, little is known of the properties of spin merons especially about their formation. It was confirmed only recently that hedgehog merons could exist in pairs with opposite helicities via a spin flux closure. However, it is unclear whether a single hedgehog meron could ever exist by pairing with another type of meron. Using element-resolved magnetic imaging measurements on epitaxial trilayer disks, we show that a spin meron with a full range of helicity, including the hedgehog meron, can be stabilized by pairing with another vortex meron with a fine tuning of the magnetic coupling between the two merons. Furthermore, the meron divergence is fully controlled by the polarity of the vortex meron, independent of the vortex helicity.

  18. Materials Data on Sr2CoCu2O7 (SG:46) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-09-30

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Coupling of quantum well states in Cu/Co/Cu system

    NASA Astrophysics Data System (ADS)

    Qiu, Z. Q.; Wu, Y. Z.; Won, C. Y.; Zhao, H. W.; Rotenberg, E.; Smith, N. V.

    2004-03-01

    Quantum well(QW) states in ultrathin metallic films are shown to play an important role in oscillatory interlayer magnetic coupling. To better understand the properties of QW states, Kawakami et al [1] used 1ML Ni to probe the QW wave function, and the result shows that the QW states in a symmetrical double QWs couple together across the Ni barrier. One interesting question is how QW states in asymmetrical double QWs interact. In this talk, we report photoemission study of Cu(d1)/Co(1ML)/Cu(d2) double QWs grown on Co(001). The experiment was performed at the Advanced Light Source. The results show strong resonance between the two Cu QW states across the 1ML Co barrier. In particular, energy spectra taken at the ratio of d1:d2=1:1, 1:2, and 1:3 show interesting coupling characters that the QW states in one layer couple selectively with the QW states of the other layer. [1] R.K. Kawakami et al Nature(London) 398,132(1999)

  20. Materials Data on CoCu2(BO3)2 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-04-22

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Imprinting topological domain structure in epitaxial Ni/Fe/Co/Cu(001)

    NASA Astrophysics Data System (ADS)

    Tan, Ali; Li, Jia; Qiu, Zi Qiang; Arenholz, Elke; Scholl, Andreas; Hwang, Chanyong

    2015-03-01

    A vortex state can be stabilized in magnetic thin films by reducing the lateral dimension of the thin film such that the shape anisotropy imposes flux-closure on the magnetic domains. In the language of skyrmions, a vortex state has a topological skyrmion charge Q = +/- 1 / 2 , with vorticity w = + 1 and helicity γ = +/- π / 2 . By tuning the interlayer coupling strength, various domain structures can be imprinted on an adjacent ferromagnetic layer. We investigated domain imprinting by cobalt (Co) vortices on nickel (Ni) layer through a face-centered-cubic (fcc) iron (Fe) interlayer in a Ni/Fe(wedge)/Co(disks)/Cu(001) trilayer system. Using element-specific X-ray Magnetic Circular Dichroism, we observed a strong antiferromagnetic IEC for 5 ML thick Fe interlayer. From the domain images of each elements obtained using Photoemission Electron Microscopy (PEEM), we observed that the relative strength of the bilinear and biquadratic exchange coupling changes as a function of Fe interlayer thickness, leading to non-collinear coupling between Ni and Co around 5.5 ML of Fe. The resulting Ni domain structures have topological skyrmion charge Q = +/- 1 / 2 , with vorticity w = + 1 but varying helicity γ.

  2. Desorption and molecular interactions on surfaces: CO/Cu(001) and Cu(011)

    NASA Astrophysics Data System (ADS)

    Peterson, L. D.; Kevan, S. D.

    1991-02-01

    We report time-resolved electron energy loss spectroscopy results for the desorption of CO from Cu(001) and Cu(011). The measurements were performed isothermally and effectively at constant coverage. We present an analysis based on a quasiequilibrium model that expresses the pseudo-first-order desorption rate constant in terms of a virial expansion. The results of this analysis demonstrate the existence of small, long-range attractive interactions as well as the expected short-range repulsive interactions between adsorbed molecules. The interplay between these two types of interactions leads to a kinetic compensation effect that can be easily understood in terms of vanishing virial coefficients. Thus, in these simple systems, the origin of the kinetic compensation effect lies in the statistical thermodynamics of the adsorbed phase, while the dynamical events associated with the desorption event apparently play a lesser role. The relationship of this analysis technique to others is investigated, and its generality is emphasized.

  3. Materials Data on CoCuP2O7 (SG:1) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-04-22

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Materials Data on Sr2CoCuSO3 (SG:99) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-09-03

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Transitions in Fe-, Co-, Cu-, and Zn-like ions of W and Re

    NASA Technical Reports Server (NTRS)

    Seely, J. F.; Brown, C. M.; Behring, W. E.

    1989-01-01

    The spectra of highly ionized W and Re were observed by using laser-produced plasmas and a 3-m grazing-incidence spectrograph. Transitions in Fe- through Zn-like ions were identified. Wavelengths in the range 7-75 A were measured with an uncertainty of + or - 0.015 A, and energy levels were derived from the measured wavelengths. The ionization limits of Cu-like W and Re were determined.

  6. Materials Data on Mn3CoCu2(PO4)6 (SG:146) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-04-22

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  7. Electrical switching of the magnetic vortex circulation in artificial multiferroic structure of Co/Cu/PMN-PT(011)

    NASA Astrophysics Data System (ADS)

    Li, Q.; Tan, A.; Scholl, A.; Young, A. T.; Yang, M.; Hwang, C.; N'Diaye, A. T.; Arenholz, E.; Li, J.; Qiu, Z. Q.

    2017-06-01

    Co films and micron sized disks were grown on top of piezoelectric PMN-PT(011) and Cu/PMN-PT(001) substrates and investigated by the Magneto-Optic Kerr Effect and Photoemission Electron Microscopy. By applying an electric field in the surface normal direction, we find that the strain of the ferroelectric PMN-PT(011) substrate induces an in-plane uniaxial magnetic anisotropy in the Co overlayer. Under specific conditions, the Co magnetic vortex could be switched between clockwise and counter-clockwise circulations. The variations of the Co vortex switching were attributed to the variations of the ferroelectric domains under the Co disks. We speculate that the switching of the magnetic vortex circulation is a dynamical process which may involve pulses of appropriate magnitude and duration of the uniaxial magnetic anisotropy delivered to the magnetic vortex.

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

    USGS Publications Warehouse

    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.

  9. Simultaneous in-situ synthesis and characterization of Co@Cu core-shell nanoparticle arrays

    SciTech Connect

    McKeown, Joseph T.; Wu, Yueying; Fowlkes, Jason D.; Rack, Philip D.; Campbell, Geoffrey H.

    2014-12-23

    Core-shell nanostructures have attracted much attention due to their unique and tunable properties relative to bulk structures of the same materials, making core-shell nanoparticles candidates for a variety of applications with multiple functionalities.[1,2] Intriguing magnetic behavior can be tailored by variation of size, interface, crystal orientation, and composition, and core-shell nanostructures with noble-metal shells yield novel optical responses[3] and enhanced electrocatalytic activity.[4]

  10. Relativistic spin - polarized theory of magnetoelastic coupling and magnetic anisotropy strain dependence: application to Co/Cu(001).

    NASA Astrophysics Data System (ADS)

    Shick, A. B.; Novikov, D. L.; Freeman, A. J.

    1997-08-01

    A self-consistent relativistic spin-polarized version of the total energy full potential linearized augmented plane wave (FLAPW) method (E. Wimmer, H. Krakauer, M. Weinert and A.J. Freeman, Phys. Rev. B 24), 864 (1981). is applied to determine the magnetoelastic coupling, orbital magnetic moment anisotropy and magnetic anisotropy energy (MAE) of a Co overlayer on Cu(001). The total energy as a function of perpendicular overlayer/substrate strain is well fitted by a parabola and the MAE (-0.36 meV) at the equilibrium is in good agreement with experiment. As discovered earlier by Wu and Freeman (R.Q. Wu and A.J. Freeman, J.Appl.Phys. 79), 6209 (1996). , we find a linear dependence of the MAE on the overlayer/substrate distance. The calculated positive effective magnetoelastic coupling coefficient (1.13 meV) is caused by a positive surface magnetoelastic anisotropy (0.23 meV). The relativistic total energy based model for ultrathin film magnetostriction yields a magnetostriction coefficient λ_001= -5.20×10-5 and an isotropic magnetostriction coefficient λ_s=-5.65×10-5 that is in very good agreement with previous studies based on a perturbative SOC treatment. The negative sign of the magnetostriction coefficient is caused by a positive surface magnetoelastic anisotropy.

  11. Materials Data on Sr2GdCoCu2O7 (SG:46) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  12. Observation of the segregation and the dissolution of the Co and the Cu in CoCu metastable alloys.

    PubMed

    Fdez-Gubieda, M L; García Prieto, A; García Arribas, A; Meneghini, C; Mobilio, S

    2001-03-01

    Metastable Co(x)Cu100-x(x=5, 10, 15, 20) alloys have been annealed at increasing temperatures in order to study the evolution of the Co cluster and its relation with the magnetotransport properties. The structure was investigated by X-ray Absorption Spectroscopy on the Co K-edge as a function of composition and annealing temperature. An anomalous trend in the structural evolution has been evidenced and related to the preculiar features observed in the magnetotransport properties.

  13. General trends in trace element utilization revealed by comparative genomic analyses of Co, Cu, Mo, Ni, and Se.

    PubMed

    Zhang, Yan; Gladyshev, Vadim N

    2010-01-29

    Trace elements are used by all organisms and provide proteins with unique coordination and catalytic and electron transfer properties. Although many trace element-containing proteins are well characterized, little is known about the general trends in trace element utilization. We carried out comparative genomic analyses of copper, molybdenum, nickel, cobalt (in the form of vitamin B(12)), and selenium (in the form of selenocysteine) in 747 sequenced organisms at the following levels: (i) transporters and transport-related proteins, (ii) cofactor biosynthesis traits, and (iii) trace element-dependent proteins. Few organisms were found to utilize all five trace elements, whereas many symbionts, parasites, and yeasts used only one or none of these elements. Investigation of metalloproteomes and selenoproteomes revealed examples of increased utilization of proteins that use copper in land plants, cobalt in Dehalococcoides and Dictyostelium, and selenium in fish and algae, whereas nematodes were found to have great diversity of copper transporters. These analyses also characterized trace element metabolism in common model organisms and suggested new model organisms for experimental studies of individual trace elements. Mismatches in the occurrence of user proteins and corresponding transport systems revealed deficiencies in our understanding of trace element biology. Biological interactions among some trace elements were observed; however, such links were limited, and trace elements generally had unique utilization patterns. Finally, environmental factors, such as oxygen requirement and habitat, correlated with the utilization of certain trace elements. These data provide insights into the general features of utilization and evolution of trace elements in the three domains of life.

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

    SciTech Connect

    Mazumder, Vismadeb; Chi, Miaofang; Mankin, Max; Liu, Yi; Metin, Onder; Sun, Daohua; More, Karren Leslie; Sun, Shouheng

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. The role of Mott-Schottky heterojunctions in PtCo-Cu2ZnGeS4 as counter electrodes in dye-sensitized solar cells.

    PubMed

    Huang, Shoushuang; He, Qingquan; Zai, Jiantao; Wang, Min; Li, Xiaomin; Li, Bo; Qian, Xuefeng

    2015-05-28

    Metastable wurtzstannite Cu2ZnGeS4 (CZGS) nanocrystals were synthesized via a hot-injection method and then used as matrixes to fabricate PtCo-CZGS heterostructured nano-particles. The formed Mott-Schottky heterojunctions in the hybrid nanocrystals promote the transfer of electrons from semiconducting CZGS to metallic PtCo, which accelerates the reduction of I3(-) to I(-) in dye-sensitized solar cells.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Yuan, Huan; Du, Xiaosong; Xu, Ming

    2016-05-01

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

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

    USDA-ARS?s Scientific Manuscript database

    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...

  20. Effect of prior aging and flat rooling on the structure and magnetic properties of alloys of the Fe-Cr-Co-Cu system

    NASA Astrophysics Data System (ADS)

    Samarin, B. A.; Kolchin, A. E.; Kal'ner, Yu. V.

    1986-09-01

    In alloys based on Fe-33% Cr-12% Co-2% Cu alloyed with 1% Al (alloy 2) or 1.5% Nb (alloy 3) the temperature for quenching to α-solid solution is reduced from 1050 (alloy 1) to 1000 (alloy 2) or 950°C (alloy 3). The temperature for the start of α-solid solution decomposition for the alloys is 935-640°C.

  1. Grain boundary diffusion and its effects on the magnetic properties of Co/Cu and Co/Cr thin film bilayers

    NASA Astrophysics Data System (ADS)

    Pellerin, J. G.; Anderson, S. G. H.; Ho, P. S.; Wooten, C.; Coffey, K. R.; Howard, J. K.; Barmak, K.

    1994-05-01

    X-ray photoelectron spectroscopy has been used to investigate grain boundary diffusion of Cu and Cr through 1000-Å-thick Co films in the temperature range of 300-400 °C. Grain boundary diffusivities were determined by modeling the accumulation of Cu or Cr on Co surfaces as a function of time at fixed annealing temperature. The grain boundary diffusivity of Cu through Co has a diffusion coefficient D0,gb of 2×104 cm2/s and an activation energy Ea,gb of 2.4 eV. Similarly, Cr grain boundary diffusion through Co thin films exhibits a D0,gb of 6×10-2 cm2/s and an Ea,gb of 1.8 eV. The Co film microstructure has been investigated before and after annealing by x-ray diffraction and transmission electron microscopy. Extensive grain growth and texturing of the magnetic film occurred during annealing for Co deposited on a Cu underlayer which is believed to influence the grain boundary diffusion process. In contrast, the microstructure of Co deposited on a Cr underlayer remained relatively unchanged upon annealing. The difference in grain growth between the two bilayers has been suggested to account for the large disparity in activation energies. Magnetometer measurements have shown that increased in-plane coercivity Hc, reduced remanence squareness S, and reduced coercive squareness S* result from grain boundary diffusion of Cu and Cr into the Co films.

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

    SciTech Connect

    Hosmer, P.; Estrade, A.; Montes, F.; Ouellette, M.; Pellegrini, E.; Schatz, H.; Aprahamian, A.; Arndt, O.; Pfeiffer, B.; Clement, R. R. C.; Mueller, W. F.; Morton, A. C.; Pereira, J.; Santi, P.; Steiner, M.; Stolz, A.; Farouqi, K.; Kratz, K.-L.; Liddick, S. N.; Mantica, P. F.

    2010-08-15

    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 (P{sub n} values) for {sup 74}Co (18{+-}15%) and {sup 75-77}Ni (10{+-}2.8%, 14{+-}3.6%, and 30{+-}24%, respectively) for the first time, and remeasured the P{sub n} values of {sup 77-79}Cu, {sup 79,81}Zn, and {sup 82}Ga. For {sup 77-79}Cu and for {sup 81}Zn we obtain significantly larger P{sub n} 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 {sup 75}Co (30{+-}11 ms) and {sup 80}Cu (170{sub -50}{sup +110} 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 better able to reproduce the A=78-80 abundance pattern inferred from the solar abundances. The new data also influence r-process models based on the neutrino-driven high-entropy winds in core collapse supernovae.

  3. Experimental investigations and phase-field simulations of triple-phase-separation kinetics within liquid ternary Co-Cu-Pb immiscible alloys

    NASA Astrophysics Data System (ADS)

    Wu, Y. H.; Wang, W. L.; Yan, N.; Wei, B.

    2017-05-01

    The phase-separation kinetics and microstructure evolution mechanisms of liquid ternary C o43C u40P b17 immiscible alloys are investigated by both the drop tube technique and phase-field method. Two successive phase separations take place during droplet falling and lead to the formation of a three-phase three-layer core-shell structure composed of a Co-rich core, a Cu-rich middle layer, and a Pb-rich shell. The Pb-rich shell becomes more and more conspicuous as droplet diameter decreases. Meanwhile, the Co-rich core center gradually moves away from the core-shell center. Theoretical analyses show that a larger temperature gradient inside a smaller alloy droplet induces the accelerated growth of the surface segregation shell during triple-phase separation. The residual Stokes motion and the asymmetric Marangoni convection result in the appearance of an eccentric Co-rich core and the core deviation degree is closely related to the droplet size and initial velocity. A three-dimensional phase-field model of ternary immiscible alloys, which considers the successive phase separations under the combined effects of Marangoni convection and surface segregation, is proposed to explore the formation mechanisms of three-phase core-shell structures. The simulated core-shell morphologies are consistent with the experimental observations, which verifies the model's validity in reproducing the core-shell dynamic evolution. Numerical results reveal that the development of three-phase three-layer core-shell structures can be attributed to the primary and then secondary phase separations dominated simultaneously by Marangoni convection and surface segregation. Furthermore, the effects of droplet temperature gradient on the growth kinetics of the surface segregation shell are analyzed in the light of phase-field theory.

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

    PubMed

    Cheruiyot, Dorothy J; Boyd, Robert S; Coudron, Thomas A; Cobine, Paul A

    2013-06-01

    Increased metal availability in the environment can be detrimental for the growth and development of all organisms in a food web. In part, this toxicity is due to biotransfer or bioaccumulation of metals between trophic levels. We evaluated the survival, growth, and development of a generalist Hemipteran predator (Podisus maculiventris) when fed herbivorous prey (Spodoptera exigua) reared on artificial diet amended with Cu, Zn, Ni, and Co. Predator nymphs were fed S. exigua larvae raised on diet amended with sublethal (Minimum Sublethal Concentration or MSC) or lethal (Minimum Lethal Concentration or MLC) concentrations of each metal, as well as control diet. We determined if metals were biotransferred or bioaccumulated from the diet to herbivore and predator, as well as if predator growth or survival was affected by herbivore diet. Podisus maculiventris fed herbivores raised on MLC levels of both Cu and Zn took significantly longer to mature to adults, whereas their overall survival was not affected by prey diet metal concentration for any metal. Adult weights were significantly reduced for predators raised on herbivores reared on diets amended with the MLC of Cu and Zn. Copper and Zn were bioaccumulated from diet to herbivore and from herbivore to predator, whereas Ni was biotransferred (although concentrations decreased as trophic level increased). The pattern for Co was more complex, with biotransfer the main outcome. Our results show that availability of metals in a food web can affect growth and development of a hemipteran predator, and that metals are transferred between trophic levels, with metal-specific biotransfer and bioaccumulation outcomes.

  5. 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

    NASA Astrophysics Data System (ADS)

    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).

  6. Structural ground states of (A ,A')Cr2O4(A = Mg, Zn; A' = Co, Cu) spinel solid solutions: Spin-Jahn-Teller and Jahn-Teller effects

    NASA Astrophysics Data System (ADS)

    Kemei, Moureen C.; Moffitt, Stephanie L.; Darago, Lucy E.; Seshadri, Ram; Suchomel, Matthew R.; Shoemaker, Daniel P.; Page, Katharine; Siewenie, Joan

    2014-05-01

    We examine the effect of small amounts of magnetic substituents in the A sites of the frustrated spinels MgCr2O4 and ZnCr2O4. Specifically, we look for the effects of spin and lattice disorder on structural changes accompanying magnetic ordering in these compounds. Substitution of Co2+ on the nonmagnetic Zn2+ site in Zn1-xCoxCr2O4 where 0 < x ≤ 0.2 completely suppresses the spin-Jahn-Teller distortion of ZnCr2O4 although these systems remain frustrated, and magnetic ordering occurs at very low temperatures of T < 20 K. On the other hand, the substitution of Jahn-Teller active Cu2+ for Mg2+ and Zn2+ in Mg1-xCuxCr2O4 and Zn1-xCuxCr2O4 where 0 < x ≤ 0.2 induce Jahn-Teller ordering at temperatures well above the Néel temperatures of these solid solutions, and yet spin interactions remain frustrated with long-range magnetic ordering occurring below 20 K without any further lattice distortion. The Jahn-Teller distorted solid solutions Mg1-xCuxCr2O4 and Zn1-xCuxCr2O4 adopt the orthorhombic Fddd structure of ferrimagnetic CuCr2O4. Total neutron scattering studies of Zn1-xCuxCr2O4 suggest that there are local AO4 distortions in these Cu2+-containing solid solutions at room temperature and that these distortions become cooperative when average structure distortions occur. Magnetism evolves from compensated antiferromagnetism in MgCr2O4 and ZnCr2O4 to uncompensated antiferromagnetism with substitution of magnetic cations on the nonmagnetic cation sites of these frustrated compounds. The sharp heat capacity anomalies associated with the first-order spin-Jahn-Teller transitions of MgCr2O4 and ZnCr2O4 become broad in Mg1-xCuxCr2O4, Zn1-xCoxCr2O4, and Zn1-xCuxCr2O4 when x > 0. We present a temperature-composition phase diagram summarizing the structural ground states and magnetic properties of the studied spinel solid solutions.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  8. 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

    USGS Publications Warehouse

    Trumbull, Robert B.; Slack, John F.; Krienitz, M.-S.; Belkin, Harvey 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 δ11B values fall into two groups. Isotopically light tourmaline (−21.7 to −7.6‰) occurs in unmineralized samples from wallrocks, late quartz veins and Mesoproterozoic granite, whereas heavy tourmaline (−6.9 to +3.2‰) 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 δ11B values of −3 to +7‰. 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 δ11B 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, but involvement of granite-derived fluids cannot be conclusively established from the present database.

  9. BINDING OF TRACE ELEMENTS (Ag, Cd, Co, Cu, Ni AND Tl) TO CYTOSOLIC BIOMOLECULES IN LIVERS OF JUVENILE YELLOW PERCH (Perca flavescens) COLLECTED FROM LAKES REPRESENTING METAL CONTAMINATION GRADIENTS.

    PubMed

    Caron, Antoine; Rosabal, Maikel; Drevet, Ophélie; Couture, Patrice; Campbell, Peter G C

    2017-10-06

    Biomolecules involved in handling cytosolic metals in the liver of the yellow perch (Perca flavescens) were characterized in juvenile fish collected from four lakes constituting metal contamination gradients. Using size-exclusion liquid chromatography coupled to an inductively-coupled mass spectrometer (SEC-ICP-MS), we determined metal distributions among ligands of different molecular weights in the cytosol, before and after a heat denaturation step designed to isolate metallothionein-like peptides and proteins (MTLPs). Silver, Cd and Cu found in the heat-stable protein (HSP) supernatants were indeed largely present as MTLP complexes, but Co, Ni and Tl, also present in the HSP supernatants, did not co-elute with MTLPs. This difference in metal partitioning is consistent with the known preference of "soft" metals such as Ag, Cd and Cu(I) for thiolated ligands, and the contrasting tendency of Co and Ni to bind to ligands with oxygen and nitrogen as donor atoms. Metal handling in the whole cytosol also reflected these differences in metal binding behavior. For Cd and Cu, the importance of the molecular weight pool that includes MTLPs increased relative to the other pools as the total cytosolic metal concentration ([M]cytosol ) increased, consistent with a concentration-dependent detoxification response. In contrast, for Ni and Tl the increase in [M]cytosol was accompanied by a marked increase in the high molecular weight (670-33 kDa) pool, suggesting that hepatic Ni and Tl are not effectively detoxified. Overall, our results suggest that metal detoxification is less effective for Ni, Tl and Co than for Ag, Cd and Cu. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  10. 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

    NASA Astrophysics Data System (ADS)

    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.

  11. STRUCTURE STABILITY AND ELECTRONIC PROPERTIES OF CumConCO (m+n=2-7) CLUSTERS

    NASA Astrophysics Data System (ADS)

    Zhu, Jun; Zhang, Xiu-Rong; Huo, Pei-Ying; Yu, Zhi-Cheng

    The structure stability and electronic properties of CumConCO (m+n=2-7) clusters have been systematically investigated using density functional theory (DFT) within the generalized gradient approximation (GGA). The results indicate that the ground state structures of CumConCO clusters obtained by adsorbing CO molecules on the top sites of stable CumCon clusters with C atoms and CO molecules have been activated during adsorption process. Cu2CO, CuCoCO, Cu3CoCO, Co4CO, Cu4CoCO and Cu3Co3CO clusters are stronger than other ground state clusters in thermodynamic stability. Cu2CO, Cu4CO and Cu6CO clusters show stronger chemical stability; Co2CO, Co4CO, Cu5CoCO, Cu3Co3CO, Cu2Co5CO and Co7CO clusters show better propensity to adsorb CO for these clusters have larger adsorption energies; Electronic states of Cu2Co3CO, CuCo4CO, Co5CO, Cu4Co3CO, Cu3Co4CO, CuCo6CO and Co7CO clusters are mainly influenced by those of 3d orbitals in Co and Cu atoms, the contribution to total magnetic moments of these clusters comes mainly from Co atoms and these clusters have high magnetism.

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

    SciTech Connect

    Ni, Ni

    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.

  13. Geologic cross sections showing the concentrations of As, Cd, Co, Cu, Cr, Fe, Mo, Ni, Pb, and Zn in acid-insoluble residues of Paleozoic rocks within the Doniphan/Eleven Point Ranger District of the Mark Twain National Forest, Missouri, USA

    USGS Publications Warehouse

    Lee, Lopaka; Goldhaber, Martin B.

    2002-01-01

    This report is a product of a U.S. Geological Survey investigation that is focused on characterizing the potential environmental impacts of lead-zinc mining within the Doniphan/Eleven Point ranger district of the Mark Twain national forest. The elemental concentrations of iron (Fe), arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), and zinc (Zn) in acidinsoluble residues are shown for boreholes along two geologic cross sections within Doniphan/Elevan Point ranger district (Figure 1). The purpose of this report is to characterize, in a general sense, the distribution of economically and environmentally important elements within the rocks and aquifers of the Doniphan/Eleven Point ranger district

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Ultralow content of Pt on Pd–Co–Cu/C ternary nanoparticles with excellent electrocatalytic activity and durability for the oxygen reduction reaction

    DOE PAGES

    Liu, Sufen; Xiao, Weiping; Wang, Jie; ...

    2016-08-01

    Optimizing the utilization of Pt to catalyze the sluggish kinetics of the oxygen reduction reaction (ORR) is of vital importance in proton exchange membrane fuel cells. One of the strategies is to spread Pt atoms over the surface of a substrate to increase the surface area. We report a facile method to synthesize Pd6CoCu@Pt/C core-shell nanoparticles with an ultralow amount of Pt. It was found that Pt-coated layer on Pd6CoCu cores plays a vital role in enhancing the ORR activity and the cycling stability. The half-wave potential of Pd6CoCu@Pt/C positively shifts about 50 mV and 17 mV relative to Pd6CoCu/Cmore » and Pt/C, respectively. The Pt mass activity on Pd6CoCu@Pt/C was calculated to be about 27 times higher than that on Pt/C catalysts at 0.9 V. Furthermore, the Pd6CoCu@Pt/C nanoparticles exhibit superior stability with almost no decay for the ORR polarization curves during 10,000 potential cycles and the core-shell structure remains with only a slight increase in the thickness of the Pt overlayer. Our findings provide a methodology for synthesizing highly efficient catalytic materials for the cathodic application in fuel cells.« less

  16. Ultralow content of Pt on Pd–Co–Cu/C ternary nanoparticles with excellent electrocatalytic activity and durability for the oxygen reduction reaction

    SciTech Connect

    Liu, Sufen; Xiao, Weiping; Wang, Jie; Zhu, Jing; Wu, Zexing; Xin, Huolin; Wang, Deli

    2016-08-01

    Optimizing the utilization of Pt to catalyze the sluggish kinetics of the oxygen reduction reaction (ORR) is of vital importance in proton exchange membrane fuel cells. One of the strategies is to spread Pt atoms over the surface of a substrate to increase the surface area. We report a facile method to synthesize Pd6CoCu@Pt/C core-shell nanoparticles with an ultralow amount of Pt. It was found that Pt-coated layer on Pd6CoCu cores plays a vital role in enhancing the ORR activity and the cycling stability. The half-wave potential of Pd6CoCu@Pt/C positively shifts about 50 mV and 17 mV relative to Pd6CoCu/C and Pt/C, respectively. The Pt mass activity on Pd6CoCu@Pt/C was calculated to be about 27 times higher than that on Pt/C catalysts at 0.9 V. Furthermore, the Pd6CoCu@Pt/C nanoparticles exhibit superior stability with almost no decay for the ORR polarization curves during 10,000 potential cycles and the core-shell structure remains with only a slight increase in the thickness of the Pt overlayer. Our findings provide a methodology for synthesizing highly efficient catalytic materials for the cathodic application in fuel cells.

  17. Ultralow content of Pt on Pd–Co–Cu/C ternary nanoparticles with excellent electrocatalytic activity and durability for the oxygen reduction reaction

    SciTech Connect

    Liu, Sufen; Xiao, Weiping; Wang, Jie; Zhu, Jing; Wu, Zexing; Xin, Huolin; Wang, Deli

    2016-08-01

    Optimizing the utilization of Pt to catalyze the sluggish kinetics of the oxygen reduction reaction (ORR) is of vital importance in proton exchange membrane fuel cells. One of the strategies is to spread Pt atoms over the surface of a substrate to increase the surface area. We report a facile method to synthesize Pd6CoCu@Pt/C core-shell nanoparticles with an ultralow amount of Pt. It was found that Pt-coated layer on Pd6CoCu cores plays a vital role in enhancing the ORR activity and the cycling stability. The half-wave potential of Pd6CoCu@Pt/C positively shifts about 50 mV and 17 mV relative to Pd6CoCu/C and Pt/C, respectively. The Pt mass activity on Pd6CoCu@Pt/C was calculated to be about 27 times higher than that on Pt/C catalysts at 0.9 V. Furthermore, the Pd6CoCu@Pt/C nanoparticles exhibit superior stability with almost no decay for the ORR polarization curves during 10,000 potential cycles and the core-shell structure remains with only a slight increase in the thickness of the Pt overlayer. Our findings provide a methodology for synthesizing highly efficient catalytic materials for the cathodic application in fuel cells.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  20. Bulk-hardened magnets based on Y2Co17

    NASA Astrophysics Data System (ADS)

    Gabay, A. M.; Zhang, Y.; Hadjipanayis, G. C.

    2001-07-01

    Bulk magnetic hardening of cast Y2Co17-based alloys was systematically studied for different compositions and heat treatments. Additions of Cu and Zr, Hf, or Ti to the Y-Co were found to be essential for developing coercivity. The performance of Y-Co-Cu-Zr magnets can be significantly improved by partial Pr and Fe substitutions for Y and Co, respectively. Anisotropic (Y0.8Pr0.2)11.5Zr2.75Co56.75Fe14Cu15 powders with intrinsic coercivity of 7.8 kOe and energy product of 14.4 MG Oe were obtained after annealing at 900 °C for 15 min and cooling to 200 °C at the rate of 4 °C/min. We also explored the effects of some other rare earths (La, Nd, Gd) and transition metals (Mn, Ni) on the magnetic properties of the Y-Co-Cu-Zr magnets. The phases present and the microstructure were analyzed with x-ray diffraction, thermomagnetic analysis, and transmission electron microscopy. The cellular/lamellar microstructure of the bulk-hardened alloys is similar to that of Sm-Co-Cu-Zr magnets. Among the most noticeable distinctions in the Y-Co-Cu-Zr alloys are a smaller average size of 2:17 cells and a variety of Zr-rich phases, like Zr2Co11 and Zr6Co23. Although the Y2Co17 phase is known to have an "easy-plane" anisotropy, the x-ray diffraction experiments with magnetically oriented powders suggest that in the bulk-hardened Y-Co-Cu-Zr and Y-Co-Cu-Fe-Zr magnets the 2:17 phase has uniaxial anisotropy.

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

    SciTech Connect

    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).

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

    NASA Astrophysics Data System (ADS)

    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.

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

    Treesearch

    I.D. Yesilonis; R.V. Pouyat; N.K. Neerchal

    2008-01-01

    We investigated the spatial distribution of heavy metal above-background (anthropic) contents of Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Ti, V, and Zn in Baltimore City surface soils and related these levels to potential contaminating sources. Composite soil samples (0?10 cm depth) were digested using a nitric and hydrochloric extraction technique. Slightly more than 10% of...

  4. Specificity of aequorin luminescence to calcium

    NASA Technical Reports Server (NTRS)

    Shimomura, O.; Johnson, F. H.

    1975-01-01

    The presence of Pb(++), Co(++), Cu(++), and Cd(++), each of which possesses a certain luminescence-triggering activity of aequorin, potentially interferes with the specificity of the aequorin luminescence response to Ca(++). Interference by the above cations can be eliminated, without influencing the sensitivity of the luminescence of aequorin to Ca(++), by adding 1 mM of sodium diethyldithiocarbamate.

  5. Protective Effects of Estradiol on Ethanol-induced Bone Loss Involves Inhibition of Reactive Oxygen Species Generation in Osteoblasts and Downstream Activation of the ERK/STAT3/RANKL Signaling Cascade

    USDA-ARS?s Scientific Manuscript database

    Bone loss occurs following chronic ethanol (EtOH) consumption in males and cycling females in part as a result of increased bone resorption. We have demonstrated in vivo that estradiol treatment can reverse this effect. Using osteoclast precursors from bone marrow and osteoblast/pre-osteoclast co-cu...

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Influence of Copper Oxidation State on the Bonding and Electronic Structure of Cobalt–Copper Complexes

    SciTech Connect

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

    2015-12-07

    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.

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

    SciTech Connect

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

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. 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

    NASA Astrophysics Data System (ADS)

    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.

  12. 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.

    PubMed

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

    2015-04-05

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    SciTech Connect

    Kucherov, A.V.; Kucherova, T.N.; Nissenbaum, V.D.

    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.

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

    PubMed Central

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

    2015-01-01

    In this study, CoCu alloy nanoparticles-incorporated carbon nanofibers are introduced as effective non precious electrocatalyst for methanol oxidation in alkaline medium. The introduced electrocatalyst has been synthesized by simple and effective process; electrospinning. Typically, calcination, in nitrogen atmosphere, of electrospun nanofibers composed of cobalt acetate, copper acetate and poly (vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The nanofibrous morphology and alloy structure have been confirmed by SEM, TEM and XRD analyses. Investigation of the electrocatalytic activity indicates that copper content has strong influence, the alloy nanoparticles having the composition Cu5%Co95% showed distinct high performance; 100 times higher than other formulations. Overall, the introduced study revealed the veil about the distinct role of copper in enhancing the electrocatalytic activity of cobalt-based materials. PMID:26568442

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

    PubMed

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  17. Sm(Co, Fe, Cu, Zr)z magnets fabricated by simple processing

    NASA Astrophysics Data System (ADS)

    Tang, W.; Zhang, Y.; Hadjipanayis, G. C.

    2000-07-01

    Optimization studies in Sm(Co, Cu, Fe, Zr)z magnets for high-temperature applications led to some compositions which develop their high coercivity with simple processing. Homogenized magnets with higher Cu and Zr content acquire a coercivity of above 20 kOe after a short aging (3 h) at 850 °C without the traditional slow cooling to 400 °C which is required for the commercial magnets. Microstructure studies showed that the homogenized magnets consist of a mixture of Sm(Co, Cu)5 precipitates in a disordered 2:17 matrix as compared to a uniform and featureless microstructure of the traditional homogenized magnets. Because of this, the time required for the full development of uniform cellular and lamellar structures with the right microchemistry is much shorter in the magnets.

  18. Effects of substrate temperature and Cu underlayer thickness on the formation of SmCo{sub 5}(0001) epitaxial thin films

    SciTech Connect

    Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki; Kirino, Fumiyoshi

    2010-05-15

    SmCo{sub 5}(0001) epitaxial thin films were prepared on Cu(111) underlayers heteroepitaxially grown on Al{sub 2}O{sub 3}(0001) single-crystal substrates by molecular beam epitaxy. The effects of substrate temperature and Cu underlayer thickness on the crystallographic properties of SmCo{sub 5}(0001) epitaxial films were investigated. The Cu atoms of underlayer diffuse into the SmCo{sub 5} film and substitute the Co sites in SmCo{sub 5} structure forming an alloy compound of Sm(Co,Cu){sub 5}. The ordered phase formation is enhanced with increasing the substrate temperature and with increasing the Cu underlayer thickness. The Cu atom diffusion into the SmCo{sub 5} film is assisting the formation of Sm(Co,Cu){sub 5} ordered phase.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A.

    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.

  1. Heavy metal concentration in sediment, benthic, benthopelagic, and pelagic fish species from Musa Estuary (Persian Gulf).

    PubMed

    Abdolahpur Monikh, Fazel; Safahieh, Alireza; Savari, Ahmad; Doraghi, Abdolmajid

    2013-01-01

    The concentration of Cd, Co, Cu, Ni, and Pb was measured in sediment and three fish species collected from Musa Estuary, Persian Gulf. The concentration order of heavy metals in sediment were Ni > Co > Cu > Pb > Cd >. Concentrations of the heavy metals in the fish were apparently different among the three species. The concentrations of Cd and Ni in fish were Johnius belangerii > Euryglossa orientalis > Liza abu, while the Co and Cu levels were L. abu > E. orientalis > J. belangerii and E. orientalis > L. abu > J. belangerii, respectively. Result of regression analysis showed that there were no significant relationships between metal concentration in fish tissues and sediment, except for Ni concentration in the J. belangerii liver. The concentrations of studied metals in fish muscle were below the permissible limits proposed by FAO, WHO, and EC.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Templated synthesis of magnetic nanowires by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Tan, Liwen

    There has been much interest in magnetic nanowire because of its perpendicular magnetic anisotropy, enhanced coercivity and large giant magnetoresistance (GMR). So, it is supposed that magnetic nanowires have potential applications to ultra-high-density magnetic recording and high sensitive sensors. Many kinds of methods have been used for the growth of nanowires with diameter ranging from 10nm to few hundred nanometers, however, template assisted electrochemical deposition exhibits many advantages on the growth of metal nanowires. In this work, two-step anodic alumina templates were fabricated for the growth of magnetic nanowires. These templates provided platforms for achieving uniform nanowires. Moreover, nano-imprinting was introduced for the formation of nanopore arrays with long-range order. A new Si3N4 thin film nano-stamp was developed, which is much simpler and more cost-effective. Also, nanopore patterning alignment was successfully achieved without using e-beam lithography. This would provide the opportunity to electrically address each single nanostructure in arrays with high density. The growth of magnetic nanowires was done by eletrodeposition, which included single element Co and Co/Cu multilayered nanowires. Their structures, magnetic and transport properties have been investigated, and were tailored by optimizing the fabrication process. It was shown that the composition of magnetic nanowires was a function of deposition potential. And the structure of electrodeposited Co was affected by the pH of electrolyte and growth rate. GMR and spin transfer torque have been performed on the Co/Cu nanowires. A GMR of 22% was achieved in Co/Cu nanowires. Different magnetoresistance behaviors were observed, which were related to the magnetic anisotropy of the nanowires. It was the first time to detect spin transfer torque in the nanowires with hundreds of Co/Cu bilayers. The switching current density was about 107A/cm2. This process demonstrated the fabrication

  4. Segregation gettering by implantation-formed cavities and B-Si precipitates in silicon

    SciTech Connect

    Myers, S.M.; Petersen, G.A.; Follstaedt, D.M.

    1998-01-01

    The authors show that Fe, Co, Cu, and Au in Si undergo strong segregation gettering to cavities and B-Si precipitates formed by He or B ion implantation and annealing. The respective mechanisms are argued to be chemisorption on the cavity walls and occupation of solution sites within the disordered, B-rich, B-Si phase. The strengths of the reactions are evaluated, enabling prediction of gettering performance.

  5. Continuous control of spin polarization using a magnetic field

    SciTech Connect

    Gifford, J. A.; Zhao, G. J.; Li, B. C.; Tracy, Brian D.; Zhang, J.; Kim, D. R.; Smith, David J.; Chen, T. Y.

    2016-05-23

    The giant magnetoresistance (GMR) of a point contact between a Co/Cu multilayer and a superconductor tip varies for different bias voltage. Direct measurement of spin polarization by Andreev reflection spectroscopy reveals that the GMR change is due to a change in spin polarization. This work demonstrates that the GMR structure can be utilized as a spin source and that the spin polarization can be continuously controlled by using an external magnetic field.

  6. A mineralized breccia pipe in Monhawk Canyon, Arizona

    SciTech Connect

    Wenrich, K.J.; Van Gosen, B.S.; Balcer, R.A.; Scott, J.H.; Mascarenas, J.F.; Bedinger, G.M.; Burmaster, B.

    1988-01-01

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

  7. Fe-Mn nodules of the Mendeleev Ridge, Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Bazilevskaya, E. S.; Skolotnev, S. G.

    2015-10-01

    The results of study of Fe-Mn crusts from the Mendeleev Ridge in the Arctic Ocean sampled with manipulators from a submarine are presented. In almost all the samples, the ore phase is significantly enriched in some valuable trace elements (Ni, Co, Cu, etc.), the contents of which exceed those in ores from the pelagic zones of other oceans. The high ore potential of the Arctic pelagic zone is stated and substantiated.

  8. Differential tolerance of Sulfolobus strains to transition metals

    USGS Publications Warehouse

    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.

  9. Spectral, Magnetic and Biological Studie on Some Bivalent 3d Metal Complexes of Hydrazine Derived Schiff-Base Ligands

    PubMed Central

    Sherazi, Syed K. A.

    1997-01-01

    Metal(II) complexes of hydrazine derived Schiff-base ligands of the type M(L)2Cl2 where M = Co, Cu, Ni and Zn and L = L1 and L2 have been prepared and characterised by molar conductance, magnetic moment, elemental analysis and electronic, IR, H-NMR and 13C spectral data.The different modes of chelation of the ligands and their comparative biological properties against different bacterial species are reported. PMID:18475770

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

    SciTech Connect

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

    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.

  11. Atomistic Modeling of Co Growth on Cu(111

    NASA Technical Reports Server (NTRS)

    Khalil, Joseph; Bozzolo, Guillermo; Farias, Daniel; deParga, Vazquez; deMiguel, J. J.; Miranda, R.

    2002-01-01

    The BFS method for alloys is applied to the study of Co growth on Cu(111). The parameterization of the Co-Cu system is obtained from first-principles calculations, and tested against known experimental features for low coverage Co deposition on Cu(100) and Cu(111). Atomistic simulations are performed to investigate the behavior of Co on Cu(111) as a function of coverage.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. In situ characterization of Cu-Co oxides for catalytic application.

    PubMed

    Tian, Z Y; Vieker, H; Kouotou, P Mountapmbeme; Beyer, A

    2015-01-01

    In situ emission and absorption FTIR methods were employed to characterize the spatially resolved structure of binary Co-Cu oxides for low-temperature oxidation of CO and propene. Co-Cu oxide catalysts were controllably synthesized by pulsed-spray evaporation chemical vapor deposition. XRD, FTIR, XPS, UV-vis and helium ion microscopy (HIM) were employed to characterize the as-prepared thin films in terms of structure, composition, optical and thermal properties as well as morphology. In situ emission FTIR spectroscopy indicates that Co3O4, CuCo2O4 and CuO are thermally stable at 650, 655 and 450 °C, respectively. The catalytic tests with absorption FTIR display that the involvement of Co-Cu oxides can initiate CO and C3H6 oxidation at lower temperatures. The results indicate that in situ emission and absorption FTIR are useful techniques to explore the thermal properties and catalytic performance of functional materials, allowing many potential applications in tailoring their temporally and spatially resolved structure-property relationships.

  14. Accumulation and distribution of metallic elements and metalloids in edible Amanita fulva mushrooms.

    PubMed

    Falandysz, Jerzy; Drewnowska, Małgorzata; Chudzińska, Maria; Barałkiewicz, Danuta

    2017-03-01

    Baseline concentrations of Ag, Al, As, Ba, Ca, Cd, Co, Cu, Cr, Fe, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr, Tl, V, U and Zn were presented in Amanita fulva collected from unpolluted areas in Poland. There is no previous data published on the bio-element constituents of A. fulva. A very narrow range of values was determined by ICP-DRC-MS and ICP-AES for the trace elements Ag, Co, Cu, Cr, Ni, Rb, Sr, Tl and Zn in caps and of Ag, Co, Cu, Mn, Ni, Sr, U and Zn in stipes and also for the macro elements K, P, Na and Mg. The fruitbodies of A. fulva from the northern (Baltic Sea coastal forests) and southwestern (Lower Silesia forests) sites differed substantially in cadmium, lead and uranium, and those from the Lower Silesia region showed them in greater concentrations. This observation may imply that A. fulva under typical geochemical site conditions is able to regulate the accumulation of many of the elements mentioned in fruiting bodies.

  15. Electrodeposition efficiency of Co and Cu in the fabrication of multilayer nanowires by polymeric track-etched templates.

    PubMed

    Pullini, D; Busquets-Mataix, D

    2011-03-01

    Co/Cu-multilayer nanowires can be exploited to develop magnetoresistive sensors. One of the easiest methods for their production is filling nanoporous templates by pulsed-electrodeposition (PED) from a single bath. Multiple parameters effecting the growth of these nano-objects must be controlled to tailor their properties. In this study, the deposition efficiency of Co/Cu-multilayer nanowires produced in nanoporous-polymeric membranes is assessed, and the influence of the space confinement produced by the nanopores themselves on the continuous and pulsed-electrodeposition is evaluated. The growth dependence on some of the most significant process parameters has been investigated. It is shown here that, for each species, when depositing Co and Cu separately, a decrease of current efficiency is observed when the charge density is increased and the pore diameter is reduced; on the contrary, in the Co/Cu-PED, changing the degree of polarization for each deposition step of the different metals results in a sensible reduction of this effect.

  16. The effect of annealing temperature on the magnetic anisotropy in Co ultrathin film on MgO(001) substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Yong-Sheng; He, Wei; Tang, Jin; Ahmad, Syed Sheraz; Zhang, Wei; Li, Yan; Zhang, Xiang-Qun; Cheng, Zhao-Hua

    2017-05-01

    Co epitaxial thin films with 2.5nm thickness were prepared on single-crystal MgO(001) substrates and annealed at different temperatures. The contribution of each interface of the MgO/Co/Cu trilayer to the in-plane magnetic anisotropy (IMA) was studied by changing interfacial coupling through annealing. The structure was measured by low energy electron diffraction (LEED), and the magnetic properties were measured using the anisotropic magnetoresistance (AMR) measurements and the longitudinal Magneto-optical Kerr effect magnetometer (MOKE). We found that the magnetic anisotropy of the as-deposited one shows superposition of a two-fold symmetry with a weak four-fold contribution caused by the stress of the interface between Co/Cu, which is along the easy axis [-110]. After annealing at 200°C, the symmetry of magnetic anisotropy was changed from uniaxial magnetic anisotropy (UMA) into four-fold symmetry due to the significant increasing of four-fold magnetocrystalline anisotropy. When the films were annealed above 300°C, the damage of the MgO/Co interface additionally decreased the IMA to isotropy. Meanwhile, the coercivity raised from 45Oe (without annealing) to 1200Oe (annealed at 400°C) along the easy axis direction. Our experimental results prove that the Co/Cu interface and the MgO/Co interface play an essential role in manipulating the four-fold and the UMA in the system.

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

    PubMed

    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).

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

    PubMed

    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.

  19. The role of electron confinement in Pd films for the oscillatory magnetic anisotropy in an adjacent Co layer

    NASA Astrophysics Data System (ADS)

    Manna, Sujit; Przybylski, M.; Sander, D.; Kirschner, J.

    2016-11-01

    We demonstrate the interplay between quantum well states in Pd and the magnetic anisotropy in Pd/Co/Cu (0 0 1) by combined scanning tunneling spectroscopy (STS) and magneto optical Kerr effect (MOKE) measurements. Low temperature scanning tunneling spectroscopy reveals occupied and unoccupied quantum well states (QWS) in atomically flat Pd films on Co/Cu (0 0 1). These states give rise to sharp peaks in the differential conductance spectra. A quantitative analysis of the spectra reveals the electronic dispersion of the Pd (0 0 1) d-band ({{ Δ }5} -type) along the Γ -X direction. In situ MOKE experiments on Pd/Co/Cu (1, 1, 13) uncover a periodic variation of the in-plane uniaxial magnetic anisotropy as a function of Pd thickness with a period of 6 atomic layers Pd. STS shows that QWS in Pd cross the Fermi level with the same periodicity of 6 atomic layers. Backed by previous theoretical work we ascribe the variation of the magnetic anisotropy in Co to QWS in the Pd overlayer. Our results suggest a novel venue towards tailoring uniaxial magnetic anisotropy of ferromagnetic films by exploiting QWS in an adjacent material with large spin-orbit coupling.

  20. Synthesis and magnetism of modulated FeCo-based nanowires

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    FeCo based nanowire arrays have been proposed for different applications as high-density magnetic storage or sprintronics. Depending on the application different magnetic properties are required and the electrochemical techniques are low-cost routes to tailor them, by tuning the nanowires composition and geometry. In this work two different types of nanowires are studied: multisegmented nanowires and nanowires with modulated diameter. The magnetic properties of multisegmented [FeCoCu(y)/Cu(x)]10 nanowire arrays have been studied considering different Cu layer thicknesses (x) and FeCoCu segment lengths (y). The obtained results show that the hard magnetic properties of these nanowire arrays present a higher coercivity and remanence comparing to the continuous nanowires, for thicker Cu layers and shorter FeCoCu segments. On the other hand, for the nanowires with modulated diameter it has been stated that the magnetization reversal process takes place by a vortex domain wall and with the tailored modulations along the nanowire it is possible to induce the domain wall pinning. This opens the possibility of controlling the domain wall motion along magnetic nanowires.

  1. Mobility of heavy metals from coal fly ash

    NASA Astrophysics Data System (ADS)

    Fernández-Turiel, J. L.; de Carvalho, W.; Cabañas, M.; Querol, X.; López-Soler, A.

    1994-06-01

    The mobility of Cd, Co, Cu, Ni, Pb, Sb, and Zn from six different coal-fired power plant fly ashes that show a wide compositional range was examined using a sequential extraction procedure in order to assess their mobility when these wastes are ponded or landfilled. The extraction sequence was as follows: (1) water extractable, (2) cation exchangeable (CH3COONH4 at pH 7), (3) surface oxide-bound cations (CH3COONH4 at pH 5), (4) Fe oxide-bound cations (HONH3Cl), and (5) residual (HF, HCl, HNO3, 2∶1∶1). The heavy metal contents in the extraction solutions were determined by anodic (Cd, Cu, Pb, Sb, and Zn) and cathodic (Ni and Co) stripping voltammetry. The results reveal differences in the total contents of the selected trace elements among the fly ash samples, which must be related to differences in coal composition and combustion technology. The extractable fraction under natural conditions ranges from 1.5 to 36.4 percent of the total element content. Cadmium, Co, Cu, and Zn show the highest extractable fraction (10.8 18.9 percent on average). Cadmium is the most easily water-extractable element, while Co, Cu, and Zn increase their mobility as the severity of the extraction increases. Cobalt, Ni, Pb, and Zn are mainly associated with the surface oxide-bound and Fe oxide-bound fractions. Nickel, Pb, and Sb have low mobility potentials (5.3 6.6 percent as extractable fraction), but Sb presents a relatively high water-extractable fraction.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Srikrishna Ramya, S.I. 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 transmittance

  4. Coercivity and nanostructure of processed SmCo_5/(CuTi) multilayer thin films*

    NASA Astrophysics Data System (ADS)

    Zhou, Jian; Liu, Yi; Skomski, Ralph; Sellmyer, David J.

    2002-03-01

    SmCo_5/(CuTi) multilayer thin films were sputtered on Si substrate with a Cr underlayer of 90 nm and coverlayer of 18 nm. The total thickness of SmCo/CuTi layers is about 160 nm. The structure of the multilayer is (SmCo_545Å/CuTiXÅ)×Y, (X = 2-10, Y =28 - 34). Xray diffraction patterns showed that after annealing between 500 ºC and 550 ºC for 30 minutes, the hexagonal 1:5 phase with average grain size of 8 nm formed. TEM images also showed that grains with diameter of 5 - 10 nm were embedded in a matrix. Hysteresis loops showed that these films have giant coercivities above 40 kOe. A maximum Hc of 50.4 kOe was obtained. For comparison, SmCo5 single layer, and SmCo_5/Cu and SmCo_5/Ti multilayers were prepared and annealed. Coercivities less than 20 kOe were obtained in these films. The giant coercivity of nanostructured SmCo_5/(CuTi) thin film can be understood as the Ti helps the Sm-Co-Cu phase form in grain boundaries, which impedes the domain-wall motion [1]. Without Ti, the annealed SmCo_5/Cu multilayer showed a relatively small Hc, less than 10 kOe. * Research supported by DOE and CMRA [1] J. Zhou, R. Skomski, C. Chen, G.C. Hadjipanayis, and D.J. Sellmyer, “Sm-Co-Cu-Ti high-temperature permanent magnets”, Appl. Phys. Lett. 77, 1514 (2000)

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

    PubMed Central

    Zhao, Ni; Lu, Xinwei; Chao, Shigang

    2014-01-01

    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. PMID:24590050

  6. Magnetic phases of fcc Fe films in the 5{endash}11 monolayer thickness range

    SciTech Connect

    Escorcia-Aparicio, E.J.; Choi, H.J.; Kawakami, R.K.; Qiu, Z.Q.

    1998-07-01

    Using the methods of artificial roughening and interfacial doping, we investigated the effects of film roughness and interdiffusion on the formation of the magnetic phase of the fcc Fe film in the Fe/Co/Cu(100) system. We found that it is the degree of film roughness that determines the magnetic phase of the fcc Fe film in the 5{endash}11 monolayer thickness range, and that the interdiffusion plays no appreciable role in the formation of the magnetic phase. {copyright} {ital 1998} {ital The American Physical Society}

  7. Trace element partitioning between taenite and kamacite - Relationship to the cooling rates of iron meteorites

    NASA Technical Reports Server (NTRS)

    Rasmussen, Kaare L.; Malvin, Daniel J.; Wasson, John T.

    1988-01-01

    Instrumental neutron activation analysis (INAA) was used to determine Ni, Co, Cu, Ga, As, Au, W, Re and Ir in taenite lamellae isolated by acid dissolution from eight iron meteorites from groups IA, IIIAB and IVA. Taenite is enriched in Ni, Cu, Ga, As, Au, W, Re and Ir relative to kamacite, whereas taenite is depleted in Co. Taenite/kamacite partition ratios in slowly cooled IAB meteorites are farther from unity than those in rapidly cooled IVA meteorites. Taenite/kamacite partition ratios for Cu, Ir, Au and Co may be sensitive cooling rate indicators.

  8. [Determination of constant and trace elements in Ranunculus ternatus thunb by ICP-AES].

    PubMed

    Chen, Jun; Yao, Cheng; Ouyang, Ping-kai

    2005-04-01

    The determination of twenty one kinds of constant and trace elements in Chinese herb Ranunculus ternatus thunb was performed by ICP-AES. The results show that K, Fe, Ca, Cr, Mg, Mn, Zn, Co, Cu, Ni, Se and Sr are relatively rich in Ranunculus ternatus and the content of Pb, Cd and As are very low. The ratio of the content of Zn to that of Cu is about 3, which is consistent with the relative content level of Zn and Cu contained in many anticancer Chinese traditional plants.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Radioactive nanoparticles and their main applications: recent advances.

    PubMed

    Kharisov, Boris I; Kharissova, Oxana V; Berdonosov, Sergei S

    2014-01-01

    Selected nanoparticles and nanocomposites on the basis of radioactive elements are reviewed. Isotopes of metallic gold, iodine and technetium salts, CeO2 and other lanthanide and actinide compounds, as well as several p- (P, C, F, Te) and d- (Fe, Co, Cu, Cd, Zn) elements form most common radioactive nanoparticles. Methods for their fabrication, including dopation with radionuclides and neutron/proton/deuteron activation, are discussed. These nanocomposites possess a series of useful applications, in particular in biology and medicine, including cancer therapeutics, drug delivery systems and radiotracers, as well as in the studies of several catalytic processes and materials structure.

  11. Analytical Applications Of Particle-Induced X-Ray Emission (PIXE)

    SciTech Connect

    Popescu, I. V.; Stihi, C.; Bancuta, A.; Dima, G.; Ene, A.; Badica, T.; Ghisa, V.

    2007-04-23

    In this paper a complex study of the capabilities of Particle-Induced X-ray Emission (PIXE) technique for the determination of major, minor and trace constituents of metallurgical, biological and environmental samples has been done. The elements identified in the metallurgical samples (steels) using PIXE were: K, Ca, V, Cr, Mn, Fe, Co, Cu, Ni, Zn, W, Ga, As, Pb, Mo, Rb, In, Rh, Zr, Pd, Nb, Sn and Sb. In the investigated biological and environmental samples (vegetals leaves, soil and mosses) PIXE analysis allowed determination of: S, Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, As, Hg and Pb.

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

    DOE PAGES

    Roman, Audrey Rae; Bond, Evelyn M.

    2016-01-14

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

  13. Magneto-optic characterizations of superlattices and wedged sandwiches with oscillatory interlayer magnetic coupling

    SciTech Connect

    Bader, S.D.

    1992-07-01

    Three examples of magnetic coupling across metallic spacer layers are considered. Fe/Nb sputtered superlattices are observed to have as many as five antiferromagnetic oscillations, but a weak magnetoresistive anomaly. Epitaxial trilayers of Fe/Mo/Fe grown on Mo(100) and Co/Cu/Co grown on Cu(100) are observed to have short- and long-period oscillations, respectively. The trilayers are grown with wedged spacer layers and characterized in-situ by means of the magneto-optic Kerr effect.

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

    SciTech Connect

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

    2009-05-01

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

  15. Synthesis of Co-based bimetallic nanocrystals with one-dimensional structure for selective control on syngas conversion

    NASA Astrophysics Data System (ADS)

    Ba, Rongbin; Zhao, Yonghui; Yu, Lujing; Song, Jianjun; Huang, Shuangshuang; Zhong, Liangshu; Sun, Yuhan; Zhu, Yan

    2015-07-01

    Co-based bimetallic nanocrystals with one-dimensional (1D) branches were synthesized by the heterogeneous nucleation of Co atoms onto prenucleated seeds, such as Pd or Cu, through a facile wet-chemical route. The peripheral branches (rod-like) of the Co-Pd and Co-Cu nanocrystals were outspread along the (001) direction and were enclosed by (101) facets. By switching the prenucleated metals to form robust Co-Pd or Co-Cu bimetallic nanocatalysts, the selectivity of CO hydrogenation could be adjusted purposely towards heavy paraffins, light olefins or oxygenates. The Anderson-Schulz-Flory chain-lengthening probabilities for products were up to 0.9 over Co-Pd nanocrystals, showing that long-chain hydrocarbons can be formed with high selectivity using the targeted design of Co-Pd nanocrystal catalysts. These Co-based bimetallic nanocrystals with a 1D structure exhibited superior catalytic activities over the corresponding Co-based nanoparticles for synthesis gas conversion.Co-based bimetallic nanocrystals with one-dimensional (1D) branches were synthesized by the heterogeneous nucleation of Co atoms onto prenucleated seeds, such as Pd or Cu, through a facile wet-chemical route. The peripheral branches (rod-like) of the Co-Pd and Co-Cu nanocrystals were outspread along the (001) direction and were enclosed by (101) facets. By switching the prenucleated metals to form robust Co-Pd or Co-Cu bimetallic nanocatalysts, the selectivity of CO hydrogenation could be adjusted purposely towards heavy paraffins, light olefins or oxygenates. The Anderson-Schulz-Flory chain-lengthening probabilities for products were up to 0.9 over Co-Pd nanocrystals, showing that long-chain hydrocarbons can be formed with high selectivity using the targeted design of Co-Pd nanocrystal catalysts. These Co-based bimetallic nanocrystals with a 1D structure exhibited superior catalytic activities over the corresponding Co-based nanoparticles for synthesis gas conversion. Electronic supplementary

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

    SciTech Connect

    Wenrich, K.J.; Van Gosen, B.S.; Balcer, R.A.; Scott, J.H.; Mascarenas, J.F.; Bedinger, G.M.; Burmaster, B.

    1988-01-01

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

  17. PIXE analysis of ancient Chinese Changsha porcelain

    NASA Astrophysics Data System (ADS)

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

    1999-04-01

    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.

  18. Development of a gas cell-based laser ion source for RIKEN PALIS

    NASA Astrophysics Data System (ADS)

    Sonoda, T.; Wada, M.; Tomita, H.; Sakamoto, C.; Takatsuka, T.; Noto, T.; Iimura, H.; Matsuo, Y.; Kubo, T.; Shinozuka, T.; Wakui, T.; Mita, H.; Naimi, S.; Furukawa, T.; Itou, Y.; Schury, P.; Miyatake, H.; Jeong, S.; Ishiyama, H.; Watanabe, Y.; Hirayama, Y.

    2013-04-01

    We developed a prototype laser ionization gas cell with a beam extraction system. This device is for use of PArasitic Laser Ion-Source (PALIS), which will be implemented into RIKEN's fragment separator, BigRIPS as a part of SLOWRI. Off-line resonant laser ionization for stable Co, Cu, Fe, Ni, Ti, Nb, Sn, In and Pd inside the gas cell, ion extraction and transport to the high-vacuum region via SPIG and QMS have been confirmed (Sonoda et al, Nucl Instrum Meth B 295:1, 2013).

  19. Metals in marine environment (mollusc Patella sp., fish Labrus bergylta, crustacean Cancer pagurus, beach sand) in a nuclear area, the North Cotentin (France).

    PubMed

    Connan, Olivier; Tack, Karine

    2010-06-01

    The results of a 1-year long survey of trace metals concentrations (Al, Cd, Cr, Co, Cu, Fe, Mn, Hg, Ni, Pb, Zn) measured in beach sand, limpets and, occasionally, in fish and shellfish from the North Cotentin area (France), where nuclear industries are implanted, are presented. The objective of these study was to provide useful data for the validation of models predicting the impact of these industries on the marine environment. Even if differences were noted between sites for various metals, the levels are consistent with existing data published for similar site and do not appear to give evidence of contamination by industrial sites.

  20. Spin-dependent Fabry-Pérot interference from a Cu thin film grown on fcc Co(001).

    PubMed

    Wu, Y Z; Schmid, A K; Altman, M S; Jin, X F; Qiu, Z Q

    2005-01-21

    Spin-dependent electron reflection from a Cu thin film grown on Co/Cu(001) was investigated using spin-polarized low-energy electron microscopy (SPLEEM). Fabry-Pe rot type interference was observed and is explained using the phase accumulation model. SPLEEM images of the Cu overlayer reveal magnetic domains in the Co underlayer, with the domain contrast oscillating with electron energy and Cu film thickness. This behavior is attributed to the spin-dependent electron reflectivity at the Cu/Co interface which leads to spin-dependent Fabry-Pe rot electron interference in the Cu film.

  1. A new Cretaceous-Tertiary boundary site at Flaxbourne River, New Zealand - Biostratigraphy and geochemistry

    NASA Technical Reports Server (NTRS)

    Strong, C. P.; Brooks, Robert R.; Wilson, Shane M.; Reeves, Roger D.; Orth, Charles J.

    1987-01-01

    On the basis of biostratigraphy data, it is shown that the Flaxbourne River Cretaceous-Tertiary boundary is among the most complete and least disturbed marine sequences yet found; this is particularly true with respect to its post-Ir anomaly and prelowermost Paleocene sequence. INAA and ICP analyses reveal that the boundary clay is also enriched in Cr and Ni, mainly from meteoritic material, and As, Co, Cu, Sb, and Zn from terrestrial sources. It is found that Zn/Sb, As/Sb, and Zn/As ratios generally fall between crustal and oceanic values, suggesting contributions from both sources.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  4. Étude Biochimique des Sécrétions Génitales de Femelles Bovines Infécondes qui Présentent des Cycles Oestrals Normaux

    PubMed Central

    Guay, P.; Lamothe, P.

    1969-01-01

    Exocervical samplings of 57 cows' genital secretions (30 normal reproducing and 27 repeat breeder cows) were studied during estrus. An attempt has been made to detect the following electrolytes: A1, Ca, Co, Cu, Fe, K, Mg, Mn, Na and Zn in these secretions. Ca, K, Mg and Na were found. No significant difference is noted in the Ca, K and Mg concentration (P>0.05) between the two groups, whereas a highly significant difference (P<0.001) in exocervical Na concentration has been measured between these groups. PMID:4238570

  5. Observation of magnetic multilayers by electron holography.

    PubMed

    Tanji, T; Hasebe, S; Nakagami, Y; Yamamoto, K; Ichihashi, M

    2004-02-01

    Magnetic structures of Co/Cu multilayers in cross section are observed by two kinds of electron holography: a Fourier method and a phase-shifting method, which is introduced briefly. The Fourier method can easily reconstruct wave functions and is applied to many specimens, whereas the phase-shifting method requires longer time for processing, but has a higher spatial resolution that permits us to discuss fine structures. Magnetization vectors in Co layers aligning parallel and separating into two blocks with antiparallel alignment are observed. Magnetic blurring on the boundary between Co and Cu in the reconstructed phase images is larger than the estimated atomic roughness.

  6. Combined optical/MCD/ODMR investigations of photochromism in doubly-doped Bi12GeO20

    NASA Astrophysics Data System (ADS)

    Briat, B.; Borowiec, M. T.; Rjeily, H. B.; Ramaz, F.; Hamri, A.; Szymczak, H.

    Electron paramagnetic resonance is detected optically via the change of magnetic circular dichroism under microwaves at 35 GHz. The technique is applied to Bi12GeO20 samples co-doped with vanadium and a second transition metal (Cr, Mn, Co, Cu). The optical and magnetic properties of several paramagnetic defects (V-Ge(4+) and Cr-Ge(4+)) are directly correlated. The basic photochromic processes occuring in samples doped with V, Mn, and Mn+V are explained. The V-Ge(4+/5+) level is positioned roughly 2.2 eV above the valence band.

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

    SciTech Connect

    Roman, Audrey Rae; Bond, Evelyn M.

    2016-01-14

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

  8. Dipole forbidden vibrational modes for NO and CO on Cu observed in the far IR

    SciTech Connect

    Hirschmugl, C.J. |; Dumas, P.; Suhren, M.; Chabal, Y.J.; Hoffmann, F.M.; Williams, G.P.

    1993-11-01

    IRRAS spectra of NO/Cu(111) and ({radical}3 {times} {radical}3)R30{degrees} coverage of CO/Cu(111) in the range 3000--180 cm{sup {minus}1} show both the adsorbate internal modes and features assigned to the hindered rotational modes. These dipole-forbidden features are characterized by asymmetric (mostly negative) absorption lineshapes and are accompanied by a change in broadband absorption. The shape and intensity of this broadband absorption is well accounted for by a scattering model.

  9. Scattering anisotropy and giant magnetoresistance in magnetic multilayers

    SciTech Connect

    Binder, J.; Zahn, P.; Mertig, I.

    2001-06-01

    We present full ab initio calculations of giant magnetoresistance (GMR) in Co/Cu (001) multilayers including self-consistent impurity scattering potentials. Starting from density functional theory the electronic structure of the multilayer and the scattering at impurities are described by means of a new Green function method. It will be demonstrated that impurity scattering in magnetic multilayers is strongly anisotropic in comparison to impurity scattering in bulk systems. Concerning transport the anisotropy of scattering leads to a formation of highly conducting channels which give rise to short circuits and cause strong variation of GMR as a function of the impurity position in the multilayer. {copyright} 2001 American Institute of Physics.

  10. Chemical intercalation of zerovalent metals into 2D layered Bi2Se3 nanoribbons.

    PubMed

    Koski, Kristie J; Wessells, Colin D; Reed, Bryan W; Cha, Judy J; Kong, Desheng; Cui, Yi

    2012-08-22

    We have developed a chemical method to intercalate a variety of zerovalent metal atoms into two-dimensional (2D) layered Bi(2)Se(3) chalcogenide nanoribbons. We use a chemical reaction, such as a disproportionation redox reaction, to generate dilute zerovalent metal atoms in a refluxing solution, which intercalate into the layered Bi(2)Se(3) structure. The zerovalent nature of the intercalant allows superstoichiometric intercalation of metal atoms such as Ag, Au, Co, Cu, Fe, In, Ni, and Sn. We foresee the impact of this methodology in establishing novel fundamental physical behaviors and in possible energy applications.

  11. Composition and origin of the unusual Oktibbeha County iron meteorite

    NASA Technical Reports Server (NTRS)

    Kracher, A.; Willis, J.

    1981-01-01

    Oktibbeha County, the most Ni-rich iron meteorite, has been analyzed for Ni, Co, Cu, Ga, Ge, As, Sb, Ir, and Au. Cu and Sb are higher than in any other iron, but other trace elements are within the ranges typically found in iron meteorites. Extrapolation of trace element trends in group IAB indicates that Oktibbeha County is a member of this group. This sheds light on the origin of groups IAB and IIICD, which are thought to be derived from impact melts on parent bodies of chondritic composition. Lafayette (iron), another sample reported in the literature to have a similarly high Ni content, is probably a pseudometeorite.

  12. Analytical Applications Of Particle-Induced X-Ray Emission (PIXE)

    NASA Astrophysics Data System (ADS)

    Popescu, I. V.; Ene, A.; Stihi, C.; Bancuta, A.; Dima, G.; Badica, T.; Ghisa, V.

    2007-04-01

    In this paper a complex study of the capabilities of Particle-Induced X-ray Emission (PIXE) technique for the determination of major, minor and trace constituents of metallurgical, biological and environmental samples has been done. The elements identified in the metallurgical samples (steels) using PIXE were: K, Ca, V, Cr, Mn, Fe, Co, Cu, Ni, Zn, W, Ga, As, Pb, Mo, Rb, In, Rh, Zr, Pd, Nb, Sn and Sb. In the investigated biological and environmental samples (vegetals leaves, soil and mosses) PIXE analysis allowed determination of: S, Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, As, Hg and Pb.

  13. Optimisation of flame parameters for simultaneous multi-element atomic absorption spectrometric determination of trace elements in rocks

    USGS Publications Warehouse

    Kane, J.S.

    1988-01-01

    A study is described that identifies the optimum operating conditions for the accurate determination of Co, Cu, Mn, Ni, Pb, Zn, Ag, Bi and Cd using simultaneous multi-element atomic absorption spectrometry. Accuracy was measured in terms of the percentage recoveries of the analytes based on certified values in nine standard reference materials. In addition to identifying optimum operating conditions for accurate analysis, conditions resulting in serious matrix interferences and the magnitude of the interferences were determined. The listed elements can be measured with acceptable accuracy in a lean to stoicheiometric flame at measurement heights ???5-10 mm above the burner.

  14. Ferromagnetism in antiferromagnetic NiO-based thin films

    NASA Astrophysics Data System (ADS)

    Lin, Yuan-Hua; Zhan, Bin; Nan, Ce-Wen; Zhao, Rongjuan; Xu, Xiang; Kobayashi, M.

    2011-08-01

    Polycrystalline NiO-based thin films with Li or/and transition metal ions (V, Cr, Mn, Fe, Co, Cu, Zn) doping have been prepared by a sol-gel spin-coating method. Magnetization measurements reveal that V-, Fe-, and Mn-doped NiO thin films show obvious room-temperature ferromagnetic behaviors and ferromagnetic properties can be enhanced by the Li co-doping. Microstructure and X-ray core-level photoemission spectra analysis indicate that the ferromagnetism was not from the impurity TM metal cluster and may be ascribed to double exchange coupling effects via Li-induced holes.

  15. Polytypic phase transitions in metal intercalated Bi2Se3

    NASA Astrophysics Data System (ADS)

    Wang, Mengjing; Koski, Kristie J.

    2016-12-01

    The temperature and concentration dependent phase diagrams of zero-valent copper, cobalt, and iron intercalated bismuth selenide are investigated using in situ transmission electron microscopy. Polytypic phase transitions associated with superlattice formation along with order-disorder transitions of the guest intercalant are determined. Dual-element intercalants of CuCo, CuFe, and CoFe-Bi2Se3 are also investigated. Hexagonal and striped domain formation consistent with two-dimensional ordering of the intercalant and Pokrovksy-Talapov theory is identified as a function of concentration. These studies provide a complete picture of the structural behavior of zero-valent metal intercalated Bi2Se3.

  16. Decomposition of equilibrium interphase boundary in substitutional alloys upon mechanical alloying

    NASA Astrophysics Data System (ADS)

    Gapontsev, V. L.; Seleznev, V. D.; Gapontsev, A. V.

    2017-07-01

    The vacancy-flux-induced decomposition of an interphase boundary in substitutional alloys has been considered. The interphase boundary decomposition has been described using the nonequilibrium thermodynamics approach, which considers a heterogeneous system to be continuous medium, including the interphase boundary. A hypothesis of local equilibrium in the thermodynamics of a continuous medium has been substituted for a more general hypothesis that takes into account the nonlocal dependence of thermodynamic forces and fluxes on order parameters. The interpretation of the formation of spatial composition modulations during the mechanical alloying of pure metallic Cu-Co, Cu-Fe, and Fe-Cr-Sn powder mixtures has been given.

  17. Electrochemical identification of metal ions in archaeological ceramic glazes by stripping voltammetry at graphite/polyester composite electrodes.

    PubMed

    Doménech-Carbó, A; Doménech-Carbó, M T; Osete-Cortina, L; Gimeno-Adelantado, J V; Bosch-Reig, F; Mateo-Castro, R

    2002-01-04

    The electrochemical response of metal ions in different samples of coloured ceramic tin-lead glazes attached to graphite/polyester composite electrodes is described. In addition to the ubiquous signals for lead, reductive dissolution processes are followed by anodic stripping peaks for Co, Cu, Sb, Mn, Sn and Fe, enabling the direct identification of such elements in microsamples proceeding from archaeological glazed tiles from Valencia (Spain) workshops (16th-18th century). Additional anodic and cathodic peaks corresponding to redox processes involving metal species in solution generated during stripping processes are also used. Peak potentials, Tafel plots and shape parameters are used for characterising the different species.

  18. Single Molecule Mechanochemistry

    NASA Astrophysics Data System (ADS)

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

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

  19. Dependence on temperature and energy of the heteroepitaxy of small metallic nanoclusters.

    PubMed

    Jiménez-Sáez, J C; Pérez-Martín, A M C; Jiménez-Rodríguez, J J

    2011-10-01

    Deposition at different energies and temperatures of small metallic nanoclusters on metallic substrates is studied by molecular-dynamics simulations. Small-, Co/Cu(001), and large-misfit, Cu/Au(001) and Au/Cu(001), systems are considered. The rise in temperature improves the epitaxial order, although its effect is smaller in large-misfit systems. Thus, by increasing this parameter, non-epitaxial clusters can turn their structure into epitaxial in the case of Co/Cu(001), into aligned in Cu/Au(001), and into layered in Au/Cu(001). Therefore, the characteristics of the alignment are determined by the properties of the material. In addition, the influence of the initial structure is more marked in Co and Cu clusters, since they can reproduce locally other phases. Epitaxy can also be improved if the deposition energy is increased, although the deposited cluster loses its original shape progressively. Its effect is different depending mainly on the degree of misfit. An increase in energy (of up to 0.75 eV/atom) produces similar effects, but more noticeable, as a rise in temperature.

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

    NASA Astrophysics Data System (ADS)

    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).

  1. Influence of marine, terrestrial and anthropogenic sources on ionic and metallic composition of rainwater at a suburban site (northwest coast of Spain)

    NASA Astrophysics Data System (ADS)

    Moreda-Piñeiro, Jorge; Alonso-Rodríguez, Elia; Moscoso-Pérez, Carmen; Blanco-Heras, Gustavo; Turnes-Carou, Isabel; López-Mahía, Purificación; Muniategui-Lorenzo, Soledad; Prada-Rodríguez, Darío

    2014-05-01

    In the present research, the rainwater chemistry of soluble (SF) and non-soluble (NSF) fractions is studied over a one a half year period (from March 2011 to August 2012) at a suburban site (Oleiros, A Coruña, Spain). The monthly rainfall in this region during the studied period ranged from 10 to 137 mm, while the NSF ranged from 0.9 to 54 mg L-1. More rainfall occurs within October-January. Eighteen samples, which provide information pertaining to the monthly variation in chemistry, were analyzed. Trace metals (Al, As, Ba, Co, Cu, Cr, Fe, Mn, Ni, Pb, Sr, V, Zn) were enclosed in the study of both fractions of the rainwater. Major inorganic ions (Cl-, NO3-, SO42-, Na+, K+, Ca2+, Mg2+ and NH4+) were also enclosed in the study of the SF of the rainwater. After partition coefficients analysis, univariate and principal components analysis (PCA) and air mass back trajectories analysis, three sources were found for the ionic and metal composition of the SF of rainwater; terrestrial (Ca2+, non sea salt SO42-, Al and Fe), marine (Mg2+, Na+, Cl-) and anthropogenic (K+, NH4+, NO3-, Fe, Mn, Pb, Sr, V and Zn). Results also suggest ubiquitous sources for Ba, Co, Cu, Cr and Ni. One source (terrestrial) was found for NSF of rainwater.

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

    PubMed

    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 (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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    PubMed Central

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

    2016-01-01

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

  5. Four reference soil and rock samples for measuring element availability in the Western Energy Regions

    USGS Publications Warehouse

    Crock, J.G.; Severson, R.C.

    1980-01-01

    Attaining acceptable precision in extractable element determinations is more difficult than in total element determinations. In total element determinations, dissolution of the sample is qualitatively checked by the clarity of the solution and the absence of residues. These criteria cannot be used for extracts. Possibilities for error are introduced in virtually every step in soil extractions. Therefore, the use of reference materials whose homogeneity and element content are reasonably well known is essential for determination of extractable elements. In this report, estimates of homogeneity and element content are presented for four reference samples. Bulk samples of about 100 kilograms of each sample were ground to pass an 80-mesh sieve. The samples were homogenized and split using a Jones-type splitter. Fourteen splits of each reference sample were analyzed for total content of Ca, Co, Cu, Fe, K, Mg, Mn, Na, and Zn; DTPA-extractable Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn; exchangeable Ca, Mg, K, and Na; cation exchange capacity water-saturation-extractable Ca, Mg, K, Na, C1, and SO4; soil pH; and hot-water-extractable boron. Error measured between splits was small, indicating that the samples were homogenized adequately and that the laboratory procedure provided reproducible results.

  6. Effect of annealing treatment on the crystallisation and leaching of dumped base metal smelter slags.

    PubMed

    Maweja, Kasonde; Mukongo, Tshikele; Mbaya, Richard K; Mochubele, Emela A

    2010-11-15

    Leaching tests of base metals contained in two smelter slags were undertaken in ammonia and nitric acid solutions aiming to recover Co, Cu and Zn. Leaching tests were conducted at 25 and 60°C at pH=0 and 3 in HNO(3) and pH=12 in NH(4)OH media. XRD analysis revealed that the dumped slags were amorphous. Annealing these slags at 1180°C produced crystalline phases comprising diopside, magnetite and fayalite. SEM and EDS analysis revealed that Cu and Pb compounds have concentrated in the magnetite phase, whereas another phase rich in Zn and Cu was located in the diopside matrix. ICP-OES analysis of the pregnant leaching solutions (PLS) showed that 30-60% of Co, Cu and Zn were released from the amorphous slags treated in HNO(3) at pH=0, and lesser in ammonia. However, the contamination by Fe and Pb was higher at pH=0. The contamination of the PLS obtained by leaching of the crystallised slags remained low. The low Fe and Pb contamination was attributed in this case to the chemical stability of the crystalline phases formed upon annealing treatment. The higher solubilisation of metals contained in amorphous slags was attributed to the collapse of silicate structures during nitric acid leaching at pH∼0. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. STM tip-mediated mass transport on Cu surfaces

    NASA Astrophysics Data System (ADS)

    Sun, Y. S. N.; Huang, R. Z.; Gao, T. F.; Zhang, R. J.; Wang, Y. M.

    2015-02-01

    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.

  8. Nanofabrication and Novel Characterization of Nanostructured Particulate Catalytic Materials

    NASA Astrophysics Data System (ADS)

    Tong, Baiyun; Upali, Siriwardane; Seetala, Naidu; Akundi, Murty; Zhong, Zhenchen

    2002-03-01

    Novel nano-particle catalysts Fe/Cu and Co/Cu will provide a promising alternative to conventional catalysts for the efficient conversion of CO/CO2/H2 gases to useful fuels. We have prepared g-Al2O3 granular support particles by sol-gel method through three steps: boehmite sol (g-AlOOH) preparation, sol gelatinization and shaping (oil dropping), and dry and calcinations. Laser induced solution deposition (LISD) is a novel method for preparing proposed nanoparticle Fe/Cu and Co/Cu catalysts, which impinged on the Al2O3 granular support. In the initial experiments, we have deposited nanostrucured pure Co/Co oxide and Fe/Fe oxide nanoparticles. We have studied the microstructure and composition of deposited nanoparticles by scanning electron microscope (SEM), X-ray diffraction analysis (XRD) and transmission electron microscope (TEM). We have investigated the magnetic and electronic structural characteristics of the deposited nanoparticle catalysts by XPS, magnetization measurements, Mossbauer study and zero field nuclear magneto resonance (ZFNMR).

  9. Multi-element analysis of manganese nodules by atomic absorption spectrometry without chemical separation

    USGS Publications Warehouse

    Kane, J.S.; Harnly, J.M.

    1982-01-01

    Five manganese nodules, including the USGS reference nodules A-1 and P-1, were analyzed for Co, Cu, Fe, K, Mg, Mn, Na, Ni and Zn without prior chemical separation by using a simultaneous multi-element atomic absorption spectrometer with an air-cetylene flame. The nodules were prepared in three digestion matrices. One of these solutions was measured using sixteen different combinations of burner height and air/acetylene ratios. Results for A-1 and P-1 are compared to recommended values and results for all nodules are compared to those obtained with an inductively coupled plasma. The elements Co, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn are simultaneously determined with a composite recovery for all elements of 100 ?? 7%, independent of the digestion matrices, heights in the flame, or flame stoichiometries examined. Individual recoveries for Co, K, and Ni are considerably poorer in two digests than this composite figure, however. The optimum individual recoveries of 100 ?? 5% and imprecisions of 1-4%, except for zinc, are obtained when Co, K, Mn, Na and Ni are determined simultaneously in a concentrated digest, and in another analytical sequence, when Cu, Fe, Mg, Mn and Zn are measured simultaneously after dilution. Determination of manganese is equally accurate in the two sequences; its measurement in both assures internal consistency between the two measurement sequences. This approach improves analytical efficiency over that for conventional atomic absorption methods, while minimizing loss of accuracy or precision for individual elements. ?? 1982.

  10. Study of Low Energy Electron Inelastic Scattering Mechanisms Using Spin Sensitive Techniques

    NASA Astrophysics Data System (ADS)

    Hsu, Hongbing

    1995-01-01

    Spin sensitive electron spectroscopies were used to study low energy electron inelastic scattering from metal surfaces and thin films. In these experiments, a beam of spin polarized electrons from a GaAs source is directed on the sample surface, and the spin polarization and intensity are measured as a function of energy loss and scattering angle by a Mott electron polarimeter coupled with a concentric hemispherical energy analyzer. Systematic studies of the angular dependence of inelastically scattered electrons were conducted on a Cu(100) surface, and Mo/Cu(100), non-magnetized Fe/Cu(100), and Co/Cu(100) films. The polarization and intensity of scattered electrons were measured as function of energy loss and scattering angle. Further studies were also conducted on Ag(100) surface and amorphous Cu/Ag(100) films. From the experimental results, the angular distributions of dipole and impact scattered electrons can be determined individually and both are found to peak in the specular scattering direction. Preliminary studies were conducted on magnetized Co/Cu(100) films. The spin dependent scattering intensity asymmetry was measured, with a clearly observable peak at energy loss of ~1 eV, which coincides with the band splitting. The polarizations of secondary electrons produced by an unpolarized primary beam were also measured. The polarizations can be related to the band polarization of magnetized cobalt films.

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

    PubMed

    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.

  12. Growth of Co and Fe on Cu(1 1 1): experiment and BFS based calculations

    NASA Astrophysics Data System (ADS)

    Farías, D.; Niño, M. A.; de Miguel, J. J.; Miranda, R.; Morse, J.; Bozzolo, G.

    2003-10-01

    The structure and morphology of Co and Fe films grown on Cu(1 1 1) have been investigated by thermal energy atom scattering (TEAS) and low-energy electron diffraction (LEED). It has been found that the growth mode of Co and Fe can be greatly improved by using Pb as surfactant, although in the case of Fe this works only for the first bilayer. This shows that the two systems exhibit decisive differences already in the first stages of the growth process. In a second series of experiments, the effect of codepositing Co-Cu and Fe-Cu on the films quality was investigated. The results are very promising, and suggest that very flat, structurally ordered fcc Fe-Cu and Co-Cu films can be prepared by applying this technique together with the use of Pb as surfactant. These results were complemented by atomistic simulations based on the BFS method for alloys. Simulations performed in the low-coverage regime suggest that the early stages of growth are governed to a great extent by the affinity of Cu for Co and Fe. We have also performed temperature-dependent Monte Carlo simulations to determine the structure of superlattices formed by codeposition of Cu-Co and Cu-Fe.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2014-01-03

    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.

  16. Self-assembly of the unique heterotrimetallic Cu/Co/M complexes possessing triangular antiferromagnetic {Cu2CoPb}2 and linear ferromagnetic {Cu2CoCd2} cores.

    PubMed

    Nesterov, Dmytro S; Kokozay, Volodymyr N; Skelton, Brian W; Jezierska, Julia; Ozarowski, Andrew

    2007-02-07

    Two novel heterotrimetallic octa-[Cu2CoPbCl4(L)4]2 (1) and pentanuclear [Cu2CoCd2Cl6(L)4(HOMe)2] (2) complexes have been prepared in one-pot reactions of zerovalent copper with metal chlorides in a methanol (for 1) or acetonitrile (for 2) solution of 2-(dimethylamino)ethanol (HL) in open air. The crystal structures of both compounds consist of discrete centrosymmetric heterotrimetallic molecules revealing triangular (1) and unique consecutive (2) arrangements of magnetic CuII(2)CoII cores. The complex 1 can be viewed as a dimer made up of tetranuclear Cu2CoPbCl4(L)4 units linked through the two micro(2)-Cl atoms. The molecular structure of 2 is a pentanuclear assembly containing the previously unknown Cu(micro-O)(2)Co(micro-O)(2)Cu core. The magnetic studies of 1 revealed an antiferromagnetic coupling (J(CoCu) = 37 cm(-1) and J(CuCu) = 87 cm(-1)) while 2 exhibits a weak ferromagnetic behavior (J(CoCu) = -3.2 cm(-1) and J(CuCu) = -14.2 cm(-1)). The correlations between magnetic behaviour and structures as well as synthetic features are also discussed.

  17. Multiple metals exposure and neurotoxic risk in bald eagles (Haliaeetus leucocephalus) from two Great Lakes states.

    PubMed

    Nam, Dong-Ha; Rutkiewicz, Jennifer; Basu, Niladri

    2012-03-01

    In the present study, the authors determined concentrations of several elements (As, Cd, Co, Cu, Cr, Mn, Pb, Sb, Zn) in the brains and livers of 46 bald eagles (Haliaeetus leucocephalus) from two Great Lakes states, Michigan and Minnesota. To explore whether exposures are of neurological concern, the authors assessed their associations with neurochemical receptors (N-methyl-D-aspartate [NMDA] and γ-aminobutyric acid A [GABA(A)]) and enzymes (glutamine synthetase [GS] and glutamic acid decarboxylase [GAD]) that play critical roles in vertebrate neurobehavior and reproduction. For most elements, levels in the livers and brains did not differ between region and gender. Hepatic Pb levels averaged 33.1 ppm (dry wt), 30.4% of all carcasses exceeded proposed avian Pb thresholds (>26.4 ppm), and in 30.8% of the birds examined evidence of Pb pellets or fragments was found. Significant changes in the activities of GS and GAD were related to brain concentrations of several metals (Pb, Cd, Co, Cu, Zn). No relationships were found among any of the nine elements and NMDA or GABA(A) receptor levels. When combined with the authors' previous study on these same eagles that showed Hg-associated alterations in GS, GAD, and NMDA receptor levels, the present research suggests that bald eagles are exposed to various elements, especially Pb and Hg, that are capable of causing changes in GABAergic and glutamatergic neurotransmission. The functional significance of these neurochemical changes warrants attention. Copyright © 2011 SETAC.

  18. First principles calculation of electrical conductivity and giant magnetroresistance of Co{vert_bar}Cu multilayers

    SciTech Connect

    Butler, W.H.; Zhang, X.G.; Nicholson, D.M.C.; MacLaren, J.M.

    1995-12-31

    We show that the Kubo formula can be used to calculate the nonlocal electrical conductivity of layered systems from first principles. We use the Layer Korringa Kohn Rostoker method to calculate the electronic structure and Green function of Co/Cu/Co trilayers within the local density approximation to density functional theory. This Green function is used to calculate the conductivity through the Kubo formula for both majority and minority spins and for alignment and anti-alignment of the Co moments on either side of the Cu spacer layer. This allows us to determine the giant magnetoresistance from first principles. We investigate three possibilities for the scattering in Co/Cu/Co: (1) equal electron lifetimes for Cu, majority spin Co, and minority spin Co, (2) equal electron lifetimes for majority and minority Co, weaker scattering in Cu and spin dependent interfacial scattering, (3) electron lifetimes for majority and minority spin cobalt proportional to their Fermi energy densities of states and spin dependent interfacial scattering.

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

    PubMed Central

    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. PMID:24387682

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

    PubMed

    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.

  1. Accumulation and source of heavy metals in sediment of a reservoir near an industrial park of northwest China

    NASA Astrophysics Data System (ADS)

    Zhu, Yuanjie; Lu, Xinwei; Yang, Linna; Wang, Lijun

    2016-12-01

    The accumulation and source of heavy metals As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in the surface sediment of a reservoir near an industrial park of northwest China were determined by enrichment factor and multi-variate statistical analysis. Multivariate statistical analyses, i.e., factor analysis, cluster analysis, and correlation coefficient analysis, were used to identify the possible sources of the heavy metals. The results show that the mean concentrations of As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in the reservoir sediment are higher than their corresponding concentrations in the control sample, indicating all analyzed heavy metals accumulated in the surface sediments. The values of the mean concentrations of heavy metals in the surface sediment divided by their corresponding concentrations in the control sample increase in the order of Ba = CrCo, Cu, Mn, Ni, Pb, V, and Zn are in the range of 2‒5, displaying moderate enrichment. Combining the results of correlation coefficient analysis, factor analysis, and cluster analysis, three main sources of these heavy metals were identified. As, Co, Cu, Mn, Ni, and V have mixed sources of natural and industrial sources and local consumption residues; Pb and Zn mainly originate from industrial activities, while Ba and Cr primarily originate from natural sources.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

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

    1999-04-01

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

  4. Concentrations of trace metals in tissues of Chionoecetes crabs (Chionoecetes japonicus and Chionoecetes opilio) caught from the East/Japan Sea waters and potential risk assessment.

    PubMed

    Hwang, Dong-Woon; Choi, Minkyu; Lee, In-Seok; Shim, Kil-Bo; Kim, Tae-Hoon

    2017-04-01

    The concentrations of trace metals (As, Cd, Co, Cu, Fe, Hg, Pb, and Zn) were measured in muscle and hepatopancreas of two Chionoecetes crabs (Chionoecetes japonicus and C. opilio) caught from the East/Japan Sea (EJS) in order to assess the potential health risk by the consumption of deep sea crabs. The highest metal concentrations in muscle and hepatopancreas were As and Fe, respectively, while the lowest metal concentration in two tissues was Pb. The mean concentrations of Cd, Co, Cu, Fe, and Pb in Chionoecetes crabs were one or two orders of magnitude higher in hepatopancreas than in muscles. The mean concentrations of As, Cu, and Hg in muscle and hepatopancreas were relatively higher in C. japonicus than in C. opilio. The estimated daily intakes (EDI) of all metals in muscle were below 0.1% of the provisional tolerable daily intake (PTDI) adopted by the Joint FAO/WHO Expert Committee on Food Additives. Similarly, the target hazard quotient (THQ) of all trace metals in muscle was less than 1.0. These results imply that Chionoecetes crabs caught from EJS do not have an adverse impact on the Korean health. Based on the mean metal concentrations, PTDI, and THQ, the daily maximum permissible intakes of C. japonicus and C. opilio were estimated to be approximately 240 and 410 g/day, respectively.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Magnetism of nanostructured permanent-magnet materials

    NASA Astrophysics Data System (ADS)

    Zhou, Jian

    Sm2Co17-type high-temperature permanent magnets with composition Sm(Co, Fe, Cu, Ti)z are investigated. The effects of Ti (or Zr), Cu, Fe and z value, as well as the effect of heat treatment on the magnetic properties are reported. Ti is found a necessity to form the cellular microstructure with grain size less than 100 nm. The Cu-rich Sm(Co, Cu)5 phase forms the grain-boundary which pins the magnetic domain-wall motion. Low Cu content makes the high-temperature coercivity vary in an abnormal way. A record-high high-temperature coercivity of 12.3 kOe at 500°C has been obtained. Granular SmCoz (z = 3--7.5) and Sm-Co-Cu-Ti thin films were produced by thermal processing of sputtered Sm-Co single layers and SmCo 5/(CuTi) multilayers. Inplane anisotropy was found in SmCoz for the composition range of z < 5.5, whereas for z > 5.5 the films exhibits three-dimensional random anisotropy. Sm-Co-Cu-Ti films were sputtered onto Si substrates with a Cr underlayer and coverlayer. X-ray diffraction patterns show that the hexagonal 1:5 phase forms after annealing. Electron micrographs of the processed films show that grains with diameters of 5 to 10 nm are embedded in a matrix. Both the grains and the matrix phase exhibit the CaCu5 Structure. The hysteresis loops show that these films have large coercivities of up to 50.4 kOe. FePt single layer and FePt/Fe multilayer thin films are prepared by magnetron sputtering. The single-phase behavior of the hysteresis loops of FePt/Fe multilayers indicates the existence of exchange coupling in these materials. An energy product of 19 MGOe has been obtained. Nanocrystalline Sm12(Co, Cu, Ti)88 powders are produced by mechanical alloying and are investigated using X-ray diffraction analysis and magnetization measurements. Different heat treatments are performed to investigate the influence on the magnetic properties and crystal structures. The intrinsic coercivity of the powders increases with an increasing amount of Cu. Short annealing time

  7. Perpendicular Giant Magnetoresistance: Study and Application of Spin Dependent Scattering in Magnetic Multilayers of Cobalt/copper and NICKEL(84) IRON(16)/COPPER

    NASA Astrophysics Data System (ADS)

    Holody, Paul Robert Joseph

    Perpendicular transport through magnetic multilayers has been successfully described by the two spin channel model. In the limit where spin flip scattering can be neglected, the transport current is carried by parallel channels of spin up and spin down electrons. Large negative magnetoresistances arise from spin dependent scattering occurring in these channels. Electrons with spins parallel to the local magnetization undergo a different amount of scattering from those with spins antiparallel to the local magnetization. Consequently the multilayer's resistance can be controlled by the relative orientation of the ferromagnetic layers' magnetizations. Usually with the relative orientation antiparallel (parallel) the multilayer has a high (low) resistance. In this dissertation, an analysis of perpendicular transport measurements in the context of the two spin channel model provides quantitative information about the amounts of spin dependent scattering at the Ferromagnetic/Normal metal interfaces and in the bulk Ferromagnet metal for the Co/Cu and Ni_{84}Fe _{16}/Cu systems (Ni_{84}Fe_{16}=Py). This is essential to the understanding of the scattering mechanisms involved in Giant Magnetoresistance. Our results show a significant bulk contribution to the spin dependent scattering; but, it is the interfaces which make the larger contribution to spin dependent scattering in these systems. A larger bulk spin dependent scattering asymmetry was determined for the Py/Cu multilayers, but not as large as expected from data derived previously from ternary alloys. Measurements were made on several Co/CuX series (where X = Pt, Mn, Ge and Ni) to study the transport properties of magnetic multilayers when significant spin flip scattering is present in the system. Analysis was done using the Valet-Fert theory which generalizes the two spin channel model to include finite spin diffusion lengths. A sharp drop in the magnetoresistance is observed when the spin diffusion length ~ layer

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

    USGS Publications Warehouse

    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

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

    PubMed

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

    2016-01-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  11. Designing novel bulk metallic glass composites with a high aluminum content

    PubMed Central

    Chen, Z. P.; Gao, J. E.; Wu, Y.; Wang, H.; Liu, X. J.; Lu, Z. P.

    2013-01-01

    The long-standing challenge for forming Al-based BMGs and their matrix composites with a critical size larger than 1 mm have not been answered over the past three decades. In this paper, we reported formation of a series of BMG matrix composites which contain a high Al content up to 55 at.%. These composites can be cast at extraordinarily low cooling rates, compatible with maximum rod diameters of over a centimetre in copper mold casting. Our results indicate that proper additions of transition element Fe which have a positive heat of mixing with the main constituents La and Ce can appreciably improve the formability of the BMG matrix composites by suppressing the precipitation of Al(La,Ce) phase resulted from occurrence of the phase separation. However, the optimum content of Fe addition is strongly dependant on the total amount of the Al content in the Al-(CoCu)-(La,Ce) alloys. PMID:24284800

  12. Atomistic Modeling of Nanostructures via the BFS Quantum Approximate Method

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Garces, Jorge E.; Noebe, Ronald D.; Farias, D.

    2003-01-01

    Ideally, computational modeling techniques for nanoscopic physics would be able to perform free of limitations on the type and number of elements, while providing comparable accuracy when dealing with bulk or surface problems. Computational efficiency is also desirable, if not mandatory, for properly dealing with the complexity of typical nano-strucured systems. A quantum approximate technique, the BFS method for alloys, which attempts to meet these demands, is introduced for the calculation of the energetics of nanostructures. The versatility of the technique is demonstrated through analysis of diverse systems, including multi-phase precipitation in a five element Ni-Al-Ti-Cr-Cu alloy and the formation of mixed composition Co-Cu islands on a metallic Cu(III) substrate.

  13. Perpendicular Giant Magnetoresistance Studies of Spin-Dependent Scattering in Magnetic Multilayers.

    NASA Astrophysics Data System (ADS)

    Yang, Qing

    1995-01-01

    We present new measurements of Giant (negative) Magnetoresistance (GMR) in Ferromagnetic/Non-magnetic (F/N) metal multilayers in the Current Perpendicular to the layer Plane (CPP) geometry. At low temperature, when the spin diffusion lengths l_sp{sf} {N} and l_sp{sf }{F} in the N and F metals are longer than the layer thicknesses, t_{N } and t_{F}, and the elastic mean-free-paths lambda _sp{el}{N} and lambda_sp{el}{F}, a simple two current, series resistor model should describe CPP data. Prior work in our group showed that this model describes well data on Co/Ag, Co/Cu, and Permalloy (Py)/Cu. The present thesis both tests this model further, and first tests an extension of the model by Valet and Fert to shorter spin-diffusion lengths. The intrinsic CPP quantity is the area A times total resistance R_{t} of the multilayer. The first study in this thesis extends work by Lee in testing the model's prediction that a plot of a certain square root quantity sqrt {[ AR_{T}(H_{o })-AR_{T}(H_{s}) ] AR_{T}(H_{o}) } versus the bilayer number N should give the same straight line for a given F/N pair and for the same pair upon alloying the N-metal with impurities (e.g., Sn) that don't flip spins. Importantly, the prediction is independent of the specific values of the parameters of the multilayer. We show that samples of Co/Ag and Co/AgSn with fixed t_{Co}=t_ {N} obey the prediction. In the previous test, the experimental quantities AR_{t}(H_{o }) and AR_{t}(H_ {s})--H_{rm o} is the state of the sample as initially prepared and H_{rm s} is the state after taking the sample to above the saturation field H_{rm s} where the resistance stops decreasing--were taken to closely represent, respectively, AR_sp{t} {AP} and AR_sp{t} {P}, the states of anti-parallel (AP) and parallel (P) alignment of the magnetizations of adjacent F layers that are assumed in the models. In our second study, we test this assumption quantitatively. We made a set of (Co/Cu/Py/Cu) _{N } quadrilayers, measured

  14. [Study on the determination of 14 inorganic elements in coffee by inductively coupled plasma mass spectrometry].

    PubMed

    Nie, Xi-Du; Fu, Liang

    2013-07-01

    Samples of coffee were digested by microwave digestion, and inorganic elements amounts of Na, Mg, P, Ca, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Mo and Pb in sample solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS). HNO3 + H2O2 was used to achieve the complete decomposition of the organic matrix in a closed-vessel microwave oven. The working parameters of the instrument were optimized. The results showed that the relative standard deviation (RSD) was less than 3.84% for all the elements, and the recovery was found to be 92.00% -106.52% by adding standard recovery experiment. This method was simple, sensitive and precise and can perform simultaneous multi-elements determination of coffee, which could satisfy the sample examination request and provide scientific rationale for determining inorganic elements of coffee.

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

    PubMed

    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.

  16. Comparison of metal accumulation in the azooxanthellate scleractinian coral (Tubastraea coccinea) from different polluted environments.

    PubMed

    Chan, Isani; Hung, Jia-Jang; Peng, Shao-Hung; Tseng, Li-Chun; Ho, Tung-Yuan; Hwang, Jiang-Shiou

    2014-08-30

    The response of metal accumulation in coral Tubastraea coccinea to various degrees of metal enrichment was investigated from the Yin-Yang Sea (YYS) receiving abandoned mining effluents, the Kueishan Islet (KI) hydrothermal vent field, and the nearshore area of remoted Green Island (GI). The concentrations of most dissolved metals were highest in seawater at YYS, followed by KI, and then GI, showing the effects of anthropogenic and venting inputs on metal levels. Five metals (Co, Fe, Mn, Ni, and Zn) yielded significant differences (p<0.05) among the skeleton samples. We identified similar patterns in the metal-Ca ratios, indicating that the elevated metals in skeletons was a consequence of external inputs. The coral tissues were relatively sensitive in monitoring metal accumulation, showing significant differences among three locations for Cd, Co, Cu, Fe, Pb, Ni, and Zn. Specific bioconcentration factors provided strong support for the differential metal accumulation in skeletons and tissues.

  17. Universal segregation growth approach to wafer-size graphene from non-noble metals.

    PubMed

    Liu, Nan; Fu, Lei; Dai, Boya; Yan, Kai; Liu, Xun; Zhao, Ruiqi; Zhang, Yanfeng; Liu, Zhongfan

    2011-01-12

    Graphene has been attracting wide interests owing to its excellent electronic, thermal, and mechanical performances. Despite the availability of several production techniques, it is still a great challenge to achieve wafer-size graphene with acceptable uniformity and low cost, which would determine the future of graphene electronics. Here we report a universal segregation growth technique for batch production of high-quality wafer-scale graphene from non-noble metal films. Without any extraneous carbon sources, 4 in. graphene wafers have been obtained from Ni, Co, Cu-Ni alloy, and so forth via thermal annealing with over 82% being 1-3 layers and excellent reproducibility. We demonstrate the first example of monolayer and bilayer graphene wafers using Cu-Ni alloy by combining the distinct segregation behaviors of Cu and Ni. Together with the easy detachment from growth substrates, we believe this facile segregation technique will offer a great driving force for graphene research.

  18. Trace metal enrichment and organic matter sources in the surface sediments of Arabian Sea along southwest India (Kerala coast).

    PubMed

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

    2015-12-30

    The geochemical distribution and enrichment of trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) were determined in the surface sediments of Arabian Sea, along southwest India, Kerala coast. The results of geochemical indices indicated that surficial sediments of five transects are uncontaminated with respect to Mn, Zn and Cu, uncontaminated to moderately contaminated with Co and Ni, and moderately to strongly contaminated with Pb. The deposition of trace elements exhibited three different patterns i) Cd and Zn enhanced with settling biodetritus from the upwelled waters, ii) Pb, Co and Ni show higher enrichment, evidenced by the association through adsorption of iron-manganese nodules onto clay minerals and iii) Cu enrichment observed close to major urban sectors, initiated by the precipitation as Cu sulfides. Correlation, principal component analysis (PCA) and cluster analysis (CA) were used to confirm the origin information of metals and the nature of organic matter composition.

  19. 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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Not Available

    1991-01-14

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

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

    SciTech Connect

    Not Available

    1991-01-14

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

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

    PubMed

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

    2006-08-01

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

  4. VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

    NASA Astrophysics Data System (ADS)

    Huang, Haibao; Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo

    2017-01-01

    Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O3, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O3 catalytic decomposition and utilization. Benzene and O3 removal efficiency reached as high as 97% and 100% after 360 min, respectively. O3 was catalytically decomposed, generating highly reactive oxidants such as rad OH and rad O for benzene oxidation.

  5. Bioaccumulation of metals in three freshwater mussel species exposed in situ during and after dredging at a coal ash spill site (Tennessee Valley Authority Kingston Fossil Plant).

    PubMed

    Otter, Ryan R; McKinney, David; Brown, Bobby; Lainer, Susan; Monroe, William; Hubbs, Don; Read, Bob

    2015-06-01

    On December 22, 2008, a dike containing coal fly ash at the Tennessee Valley Authority Kingston Fossil Plant (TN, USA) failed, and within months, dredging operations began to remove ash-contaminated sediments. The purpose of this study was to investigate differences in the bioaccumulation of metals in three mussel species during and after dredging operations. Mussels were caged for approximately 1 year during dredging and after, and then mussel condition index values and As, Cd, Cr, Pb, Ni, Se, Hg, U, Fe, Mg, Al, Sb, Ba, Be, Co, Cu, Mn, Mo, Ag, Sr, Tl, V, and Zn concentrations in soft tissue were determined via inductively coupled plasma-mass spectrometery. Overall, the differences observed in metal bioaccumulation and mussel health suggest that mussels in the immediate downstream area of the dredging site may have been impacted, as evidenced by a significant decrease in mussel condition index values, but that this impact did not result in increased tissue concentrations of metals.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  7. Mixed polyanion glass cathodes: Glass-state conversion reactions

    DOE PAGES

    Kercher, Andrew K.; Kolopus, James A.; Carroll, Kyler; ...

    2015-01-01

    Mixed polyanion (MP) glasses can undergo glass-state conversion (GSC) reactions to provide an alternate class of high-capacity cathode materials. GSC reactions have been demonstrated in phosphate/vanadate glasses with Ag, Co, Cu, Fe, and Ni cations. These MP glasses provided high capacity and good high power performance, but suffer from moderate voltages, large voltage hysteresis, and significant capacity fade with cycling. Details of the GSC reaction have been revealed by x-ray absorption spectroscopy, electron microscopy, and energy dispersive x-ray spectroscopy of ex situ cathodes at key states of charge. Using the Open Quantum Materials Database (OQMD), a computational thermodynamic model hasmore » been developed to predict the near-equilibrium voltages of glass-state conversion reactions in MP glasses.« less

  8. Structural controls and evolution of gold-, silver-, and REE-bearing copper-cobalt ore deposits, Blackbird district, east-central Idaho: Epigenetic origins

    USGS Publications Warehouse

    Lund, K.; Tysdal, R.G.; Evans, K.V.; Kunk, M.J.; Pillers, R.M.

    2011-01-01

    Textural data at all scales indicate that the host sites for veins and the tectonic evolution of both host rocks and mineral deposits were kinematically linked to Late Cretaceous regional thrust faulting. Heat, fluids, and conduits for generation and circulation of fluids were part of the regional crustal thickening. The faulting also juxtaposed metaevaporite layers in the Mesoproterozoic Yellowjacket Formation over Blackbird district host rocks. We conclude that this facilitated chemical exchange between juxtaposed units resulting in leaching of critical elements (Cl, K, B, Na) from metaevaporites to produce brines, scavenging of metals (Co, Cu, etc) from rocks in the region, and, finally, concentrating metals in the lower-plate ramp structures. Although the ultimate source of the metals remains undetermined, the present Cu-Co ± Au (± Ag ± Ni ± REE) Blackbird ore deposits formed during Late Cretaceous compressional deformation.

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

    PubMed

    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 < or = 0.01). There was a difference in the average content of the element such as K, V, Fe, Co, Cu and Sr between them (P < or = 0.05). And there was no 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.

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

    PubMed

    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.

  11. Experimental study of magnetization reversal processes in nonsymmetric spin valve

    NASA Astrophysics Data System (ADS)

    Gornakov, V. S.; Nikitenko, V. I.; Bennett, L. H.; Brown, H. J.; Donahue, M. J.; Egelhoff, W. F.; McMichael, R. D.; Shapiro, A. J.

    1997-04-01

    We have investigated a nonsymmetric bottom giant magnetoresistance spin valve with the structure Si/NiO/Co/Cu/Co/Ta, as well as single ferromagnetic Co layers on antiferromagnetic NiO, with or without a nonmagnetic Cu spacer. Magnetic hysteresis loops have been measured by SQUID magnetometry, and magnetic domain structures have been imaged using an advanced magneto-optical indicator film (MOIF) technique. The MOIF technique demonstrated that the first stage of magnetization reversal is characterized by nucleation of many microdomains. With increasing reversed field, the domain walls move over small distances (5-20 μm) until annihilation. The domain size was observed to increase with the thickness of the Co layer. When an alternating magnetic field was applied, the domain structure was dramatically changed.

  12. Distribution, enrichment and accumulation of heavy metals in coastal sediments of Alang-Sosiya ship scrapping yard, India.

    PubMed

    Reddy, M Srinivasa; Basha, Shaik; Sravan Kumar, V G; Joshi, H V; Ramachandraiah, G

    2004-06-01

    Since its inception in 1982, the Alang-Sosiya yard has become the largest ship scrapping works in the world. Several hundreds of ships arrive every year. The degree of heavy metal contamination has been studied in bulk and fine sediments from the intertidal zone of this ship scrapping yard, two stations, one on either side at 5 km distance and one reference station 60 km distance near Mahuva, towards the south. The samples have been subjected to a total digestion technique and analysed for elements: Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Zn and Al, and %TOC. The absolute metal concentrations reflected variations in BF and FF sediment samples with organic matter content. Enrichment factors (EF) and geoaccumulation indices (Igeo) have been calculated and the relative contamination levels are assessed at these sites. At Alang-Sosiya, the enrichment of heavy metals has been observed to be relatively high.

  13. Theoretical studies of CO and NO on CuO and Cu 2O(110) surfaces

    NASA Astrophysics Data System (ADS)

    Duan, Yuhua; Zhang, Kaiming; Xie, Xide

    1994-12-01

    The characteristics of CO and NO adsorption on surfaces of CuO(110) and Cu 2O(110) have been studied by using the self-consistent-charge discrete variational X a method (SCC-DV-X a). The calculated results show that the CO and NO molecules are perpendicularly adsorbed on cuprous ions of Cu 2O and cupric ions of CuO, respectively and with oxygen pointing upward in both cases. The order of chemisorption energy of the four adsorbed systems is: CuO-NO > Cu 2O-CO > Cu 2O-NO > CuO-CO. In all chemisorptions discussed d orbitals of Cu do play an important role.

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

    PubMed

    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.

  15. Detection of anthropogenic Cu, Pb and Zn in continental shelf sediments off Sydney, Australia--a new approach using normalization with cobalt.

    PubMed

    Matthai, C; Birch, G

    2001-11-01

    Concentrations of Co, Cu, Pb and Zn were determined in 107 surficial sediment samples from the continental margin adjacent to Sydney, Australia. The spatial distributions of trace metals in the sediments and the mud content are similar and increase with greater distance from the coast. In contrast, normalization of the concentrations of Cu, Pb and Zn in the total sediment with Co enables a coastal anthropogenic source to be identified. The spatial distribution of Co-normalized concentrations of Cu, Pb and Zn in total sediment is similar to the distribution of these trace metals in the fine fraction of sediment (<62.5 microm), indicating that Co may be used as a normalizing element for determining contaminant sources in the marine environment near Sydney.

  16. Determining the geographical origin of Sechium edule fruits by multielement analysis and advanced chemometric techniques.

    PubMed

    Hidalgo, Melisa J; Fechner, Diana C; Marchevsky, Eduardo J; Pellerano, Roberto G

    2016-11-01

    This paper describes the determination and evaluation of the major and trace element composition (Al, As, Ba, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Pb, Sr and Zn) of Sechium edule (Jacq) Swartz fruits collected from four different places of production in Corrientes province, Argentina. Element concentrations were determined by using inductively coupled plasma optical emission spectrometry (ICP OES) after microwave digestion. The accuracy was confirmed with standard reference material of spinach leaves (NIST, 1570a) and spiking tests. Principal component analysis (PCA), linear discriminant analysis (LDA), k-nearest neighbors (kNN), partial least square-discriminant analysis (PLS-DA) and support vector machine (SVM) were applied to the results for discriminating the geographical origin of S. edule fruits. Finally, the LDA method was found to perform best with up to 90% accuracy rate based on the following elements: Ca, Ba, Cu, Mn, Na, Sr, and Zn.

  17. Tritium Production from Palladium Alloys

    SciTech Connect

    Claytor, T.N.; Schwab, M.J.; Thoma, D.J.; Teter, D.F.; Tuggle, D.G.

    1998-04-19

    A number of palladium alloys have been loaded with deuterium or hydrogen under low energy bombardment in a system that allows the continuous measurement of tritium. Long run times (up to 200 h) result in an integration of the tritium and this, coupled with the high intrinsic sensitivity of the system ({approximately}0.1 nCi/l), enables the significance of the tritium measurement to be many sigma (>10). We will show the difference in tritium generation rates between batches of palladium alloys (Rh, Co, Cu, Cr, Ni, Be, B, Li, Hf, Hg and Fe) of various concentrations to illustrate that tritium generation rate is dependent on alloy type as well as within a specific alloy, dependent on concentration.

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

    PubMed

    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.

  19. Influence of the coat color on the trace elemental status measured by particle-induced X-ray emission in horse hair.

    PubMed

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

    2005-02-01

    The influence of hair color on the trace elemental status in horse's hair has been studied. A current analytical technique such as particle-induced X-ray emission (PIXE) used in this study has provided reliable, rapid, easy, and relatively inexpensive diagnostic methods. Twenty-eight elements (Al, Br, Ca, Cl, Co, Cu, Cr, Fe, Ga, Hg, K, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Se, Si, Sr, Ti, V, Y, and Zn) in mane hair were detected by the PIXE method. The gray hair contains significantly greater amounts of Cu, Ti, and Zn, and lower amounts of Br, Ca, Se, and Sr than those in other colored horse hairs (p<0.05). Those results measured in the horse's hair were similar to those found in human and dog hair. When interpreting a result, it should be kept in mind that hair color, especially gray hair, influences the concentrations of some elements in horse hair.

  20. Metal gettering by boron-silicide precipitates in boron-implanted silicon

    SciTech Connect

    Myers, S.M.; Petersen, G.A.; Headley, T.J.; Michael, J.R.; Aselage, T.A.; Seager, C.H.

    1996-09-01

    We show that Fe, Co, Cu, and Au impurities in Si are strongly gettered to boron-silicide precipitates formed by supersaturation B implantation and annealing. Effective binding free energies relative to interstitial solution range form somewhat above 1 to more than 2 eV. The B-Si precipitates formed at temperatures {le}1100{degrees}C lack long range structural order but closely resemble and icosahedral B{sub 3}Si phase in composition, local bonding, and chemical potential. Evidence indicates that the metal atoms go into solution in the B-Si phase, and this is interpreted in terms of the novel bonding and structural characteristics of B-rich icosahedral compounds.

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

    PubMed

    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.

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

    DTIC Science & Technology

    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

  3. Reactivity of surface carbonyl complexes in NO reduction with CO on copper-containing high-silica zeolites

    SciTech Connect

    Ukharskii, A.A.; Il`ichev, A.N.; Matyshak, V.A.

    1995-09-01

    Two mechanisms of NO reduction with CO were revealed on copper-containing high-silica zeolites. The low-temperature mechanism (below 300{degrees}C) involves the interaction between NO and CO adsorbed on Cu{sup +} with the formation of N{sub 2}0 and CO{sub 2}. The high-temperature mechanism (above 300{degrees}C) includes the interaction of CO molecules, adsorbed on Cu{sup +} ions, with NO molecules, adsorbed on copper atoms, with the formation of N{sub 2} and CO{sub 2}. Under reaction conditions, a surface carbonyl complex, CO-Cu{sup +} is observed. Quantitative spectrokinetic data provide evidence for the intermediacy of the carbonyl complex in both mechanisms. A correlation between the activity in the reaction of NO reduction with CO and the amount of Cu{sup O} atoms in the sample is found.

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

    PubMed

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

    2015-03-01

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

  5. Impact of biofumigation with solarization on degradation of pesticides and heavy metal accumulation.

    PubMed

    Flores, Pilar; Lacasa, Alfredo; Fernández, Pedro; Hellín, Pilar; Fenoll, José

    2008-08-01

    A greenhouse study was conducted to evaluate the effect of biofumigation (with sheep and chicken manure) combined with solarization on the dissipation of pesticides (pyrifenox, DDT and dieldrin), and on soil metals accumulation. The treatments consisted of a control, and soil disinfestations by biofumigation combined with solarization (B+S) for two, four, five, six consecutive years. B+S enhanced the dissipation of pyrifenox with regard to control treatment. Significant differences were not detected among plots disinfected with B+S for consecutive years. On the other hand, B+S had no effect on the dissipation of DDT and dieldrin, probably due to the resistance of these pesticides to microbial degradation and/or high temperatures. Biofumigation is considered to be an environmentally safe practice, since no accumulation of heavy metals such as Cd, Co, Cu, Cr, Pb, Ni, or Zn was observed after the subsequent application of organic matter through the treatments.

  6. Analysis of essential elements in Pito—a cereal food drink and its brands by the single-comparator method of neutron activation analysis

    PubMed Central

    Adazabra, Aaron N; Ntiforo, Apori; Bamford, Samuel A

    2014-01-01

    Instrumental neutron activation analysis using the single-comparator method has been used for the multielement determination of essential elements in two main types of Pito brewed locally in Ghana. The precision and accuracy of the analytical method was validated and found to be within 10%. In all, eight different brands of Pito depending on the type of cereal crop used in brewing were analyzed for 13 different elements (Al, As, Ba, Cl, Co, Cu, Fe, K, Mg, Mn, Na, Si, and Zn). It was observed that all brands were particularly enriched in nutrient elements Cl, Mg, and K. The rest were generally found in varying concentrations. As these elements are bioavailable in natural form, perhaps in combination with organic constituents, they are likely to be easily digested and assimilated by the human body. Arsenic, a toxic element, was found in insignificant amounts suggesting that it was within safe limits. PMID:24936292

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

    SciTech Connect

    Narsimulu, D.; Satyanarayana, N.; Venkateswarlu, M.

    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.

  8. Ecological risk assessment of a coastal zone in Southern Vietnam: Spatial distribution and content of heavy metals in water and surface sediments of the Thi Vai Estuary and Can Gio Mangrove Forest.

    PubMed

    Costa-Böddeker, Sandra; Hoelzmann, Philipp; Thuyên, Lê Xuân; Huy, Hoang Duc; Nguyen, Hoang Anh; Richter, Otto; Schwalb, Antje

    2017-01-30

    Enrichment of heavy metals was assessed in the Thi Vai Estuary and in the Can Gio Mangrove Forest (SE, Vietnam). Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn contents in water and in sediments were measured. Total organic carbon, nitrogen, phosphorus and C/N ratios were determined. Cu and Cr values were higher than threshold effect level of toxicity, while Ni exceeded probable effect level, indicating the risk of probable toxicity effects. Enrichment factors (EF), contamination factor (CF) and Geo-accumulation index (I-geo) were determined. CF reveals moderate to considerable pollution with Cr and Ni. EF suggests anthropogenic sources of Cr, Cu and Ni. I-geo indicates low contamination with Co, Cu and Zn and moderate contamination with Cr and Ni. Overall metal contents were lower than expected for this highly industrialized region, probably due to dilution, suggesting that erosion rates and hydrodynamics may also play a role in metal contents distribution.

  9. Effects of thermal stress induced by cyclic heat treatment on sintered (Nd, Dy)-Fe-B magnets

    NASA Astrophysics Data System (ADS)

    Kim, Se Hoon; Kim, Hoon-sup; Lee, Young Jung; Kim, Dae-Gun; Kim, Young Do

    2010-12-01

    We investigated the mechanisms of coercive force enhancement on Nd11Dy4Fe76.5TM2.5B6 (TM = Co, Cu, Al) induced by a number of cyclic heat treatments (CHT) at temperatures from 350°C to 450°C. The difference in thermal expansion coefficients between Nd-rich and Nd2Fe14B phases induced penetration of the Nd-rich phase into the Nd2Fe14B grain boundary through capillary force and compress pressure by CHT. Also, dislocations in the Nd2Fe14B grain were formed by thermal stresses from thermal expansion and contraction, which caused the domain wall pinning effect. Consequently, coercivity was enhanced from 2,303 kA/m before CHT to 2,480 kA/m after CHT, and a remanence of 1.18 T was maintained after two cycles.

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

    SciTech Connect

    Ivanov, Yu. P.; Zotov, A. V.; Ilin, A. I.; Davydenko, A. V.

    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.

  11. Designing novel bulk metallic glass composites with a high aluminum content.

    PubMed

    Chen, Z P; Gao, J E; Wu, Y; Wang, H; Liu, X J; Lu, Z P

    2013-11-27

    The long-standing challenge for forming Al-based BMGs and their matrix composites with a critical size larger than 1 mm have not been answered over the past three decades. In this paper, we reported formation of a series of BMG matrix composites which contain a high Al content up to 55 at.%. These composites can be cast at extraordinarily low cooling rates, compatible with maximum rod diameters of over a centimetre in copper mold casting. Our results indicate that proper additions of transition element Fe which have a positive heat of mixing with the main constituents La and Ce can appreciably improve the formability of the BMG matrix composites by suppressing the precipitation of Al(La,Ce) phase resulted from occurrence of the phase separation. However, the optimum content of Fe addition is strongly dependant on the total amount of the Al content in the Al-(CoCu)-(La,Ce) alloys.

  12. Assessment of the anthropogenic influx of metallic pollutants in the Sefidrud delta, Gilan Province, Iran.

    PubMed

    Rafiei, Behrouz; Ahmadi-Ghomi, Fatemeh; Karimkhani, Afshin

    2017-08-15

    Understanding the anthropogenic effects on the Sefidrud delta, the concentration of six metals (Cr, Co, Cu, Ni, Pb and Zn) was measured in two sites included the old Sefidrud delta (Amirabad, 23 samples) and the new Sefidrud delta (Kiashahr, 24 samples). Geoaccumulation Index (Igeo), Enrichment Factor (EF), Contamination Factor (CF) and Pollution Load Index (PLI) were used to determine the metal pollution in all sediment samples. Although the EF, Igeo, CF and PLI results in the old delta indicate no significant pollution, sediment samples in the new delta show a considerable pollution. Since the sediment source and the lithology of the Sefidrud River drainage basin did not change in the past 500years, the metal pollution in the new delta must be from anthropogenic sources. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    SciTech Connect

    Mat, I. )

    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.

  14. Wind - Ceiling - Visibility Data at Selected Airports. Volume III. Part A. Southern Region.

    DTIC Science & Technology

    1981-06-01

    IDa : Z E a: n .I -7 CD 01) CD iC. Li’ C-)- In -J [P- - - -p (n - -p ’T-r L,~~i _D (n - ’)L...D : IF .. iiri coC ) L C co cu~1~CLK r. ~ 1KVr7nt~ L r\\ zlj -H CrD N . . . ’T Lf, u:- M "J Li ... ~ ~ . ~ ..- CD-nD (I- F 0 ’ 0 -F-2 MI *1 04 a:2 -jX...En CrD ( 27. m ~ ~ ~ ~ ~ [ LO LI)000 00 d CD CD (z) 0 DC o C( 0i m . .. . . . 0D 0 D ) U~ *~0 zi. 73 r- __ O__ ___ ___N_ __OD___ __ ____C CL 2 -_- -

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  16. Extracellular compounds produced by bacterial consortium promoting elements mobilization from polymetallic Kupferschiefer black shale (Fore-Sudetic Monocline, Poland).

    PubMed

    Włodarczyk, Agnieszka; Stasiuk, Robert; Skłodowska, Aleksandra; Matlakowska, Renata

    2015-03-01

    Culture experiments employing Fe-deficient medium showed that a consortium of indigenous microorganisms isolated from Kupferschiefer black shale produced a mixture of extracellular compounds containing siderophores which could form complexes with a wide range of elements and were able to mediate element mobilization from polymetallic black shale. The mobilization of a diverse array of elements including a number of essential trace elements (Co, Cu, Mn, Mo, Zn) and toxic species (As) was shown. Since the bacteria used in this study were originally obtained from a subsurface copper deposit, these results highlight the potential importance of extracellular compounds in biogeochemical cycles of elements in underground environment and their ecological significance in promoting the uptake of essential trace metals and resistance to toxic elements.

  17. Toxic and micronutrient elements in organic, brown and polished rice in Brazil.

    PubMed

    Poletti, Jucelaine; Pozebon, Dirce; de Fraga, Marcus Vinicius Barcellos; Dressler, Valderi Luiz; de Moraes, Diogo Pompéu

    2014-01-01

    Concentration levels of As, Cd, Hg, Pb, Tl, Sn, Sb Co, Cu, Mn, Se, Zn, Cr, Ni and Mo in different types of rice cultivated in irrigated fields in Brazil were evaluated. Arsenic, Cd, Pb, Zn, Mn and Cu were found in higher concentrations in brown rice samples, suggesting the prevalence of these elements in the bran. Meanwhile, lower concentrations of Pb, Mo, Cr, Se and Co were found in parboiled rice. Organic rice did not differ of cultivated conventionally rice. Thallium, Hg and Sb were not detected in any rice sample whose limits of detection were 0.7 μg kg(-1), 2.5 μg kg(-1) and 8 μg kg(-1), respectively. The concentrations of the investigated elements were compared with those reported for polished rice and brown rice from other countries, unveiling concentrations in general at the same level for rice produced at non-contaminated sites.

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

    USGS Publications Warehouse

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

    1984-01-01

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

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

    SciTech Connect

    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

  20. Characterizing structural and vibrational properties of nanoparticles embedded in silica with XAS, SAXS and auxiliary techniques

    SciTech Connect

    Araujo, Leandro L.; Kluth, Patrick; Giulian, Raquel; Sprouster, David J.; Ridgway, Mark C.; Johannessen, Bernt; Foran, Garry J.; Cookson, David J.

    2009-01-29

    Synchrotron-based techniques were combined with conventional analysis methods to probe in detail the structural and vibrational properties of nanoparticles grown in a silica matrix by ion implantation and thermal annealing, as well as the evolution of such properties as a function of nanoparticle size. This original approach was successfully applied for several elemental nanoparticles (Au, Co, Cu, Ge, Pt) and the outcomes for Ge are reported here, illustrating the power of this combined methodology. The thorough analysis of XANES, EXAFS, SAXS, TEM and Raman data for Ge nanoparticles with mean diameters between 4 and 9 nm revealed that the peculiar properties of embedded Ge nanoparticles, like the existence of amorphous Ge layers between the silica matrix and the crystalline nanoparticle core, are strongly dependent on particle size and mainly governed by the variation in the surface area-to-volume ratio. Such detailed information provides valuable input for the efficient planning of technological applications.

  1. Heavy metals in soils along unpaved roads in south west Cameroon: Contamination levels and health risks.

    PubMed

    Ngole-Jeme, Veronica M

    2016-04-01

    Soils enriched with heavy metals from vehicular emission present a significant exposure route of heavy metals to individuals using unpaved roads. This study assessed the extent of Cd, Cr, Co, Cu, Ni, Pb and Zn contamination of soils along unpaved roads in Cameroon, and the health risks presented by incidental ingestion and dermal contact with the soils using metal contamination factor (CF) pollution load index, hazard quotients (HQ) and chronic hazard index (CHI). CF values obtained (0.9-12.2) indicate moderate to high contamination levels. HQ values for Cr, Cd and Pb exceeded the reference doses. Moderate health hazard exists for road users in the areas with intense anthropogenic activities and high average daily traffic (ADT) volume according to CHI values (1-4) obtained. The economy and quality of life in cities with unpaved roads could be threatened by health challenges resulting from long-term exposure to heavy metal derived from high ADT volumes.

  2. Environmental geochemical study of Red Mountain--an undisturbed volcanogenic massive sulfide deposit in the Bonnifield District, Alaska range, east-central Alaska: Chapter I in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

    USGS Publications Warehouse

    Eppinger, Robert G.; Briggs, Paul H.; Dusel-Bacon, Cynthia; Giles, Stuart A.; Gough, Larry P.; Hammarstrom, Jane M.; Hubbard, Bernard E.

    2007-01-01

    Water samples with the lowest pH values, highest specific conductances, and highest major- and trace-element concentrations are from springs and streams within the quartz-sericite-pyrite alteration zone. Aluminum, As, Cd, Co, Cu, Fe, Mn, Ni, Pb, Y, and particularly Zn and the REEs are all found in high concentrations, ranging across four orders of magnitude. Waters collected upstream from the alteration zone have near-neutral pH values, lower specific conductances, lower metal concentrations, and measurable alkalinities. Water samples collected downstream of the alteration zone have pH values and metal concentrations intermediate between these two extremes. Stream sediments are anomalous in Zn, Pb, S, Fe, Cu, As, Co, Sb, and Cd relative to local and regional background abundances. Red Mountain Creek and its tributaries do not support, and probably never have supported, significant megascopic faunal aquatic life.

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

    PubMed

    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.

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

    SciTech Connect

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

    2006-08-15

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

  5. EXAFS study of Cu/C catalysts

    NASA Astrophysics Data System (ADS)

    Kriventsov, V. V.; Klimov, O. V.; Kikhtyanin, O. V.; Ione, K. G.; Kochubey, D. I.

    2000-06-01

    A local arrangement of copper in Cu/C catalysts for dimethylcarbonate synthesis was studied by EXAFS. The samples with various Cu content were prepared by impregnating of carbon carrier "Sibunit" with the alcohol solution of CuCl 2. It was determined, that the oxygen atoms from surface groups of carrier always enter into copper surrounding and the relative content of oxygen drops with the increase of Cu content in the samples. The structure of surface copper compounds for initial catalysts was proposed. Thus, samples with low Cu content (9×10 -4 mol/g-cat) possess surface compounds [carrier-COO-CuCl] or [carrier-CO-CuCl], further, by increasing copper content a second surface layer consisting of hydrated CuCl 2 non-bounded with carrier is formed.

  6. Pr-Zr-Co precipitation-hardened magnet

    NASA Astrophysics Data System (ADS)

    Gabay, A. M.; Zhang, Yong; Hadjipanayis, G. C.

    2000-06-01

    Hard magnetic properties have been found in homogenized and subsequently aged Pr-Zr-Co alloys. Transmission electron microscopy reveals a microstructure consisting of a Pr2(Co, Zr)17 matrix with (Pr, Zr)Co5 precipitates formed after aging the homogenized alloys with the (Pr, Zr)Co5+δ structure. This microstructure is similar to that of the Sm-Co-Cu-Zr precipitation-hardened magnets. However, unlike Sm2Co17, the easy magnetization direction (EMD) of Pr2Co17 lies in a basal plane. The coexistence of the 2:17 matrix phase with EMD∥(001) and the 1:5 cell-boundary phase with EMD∥[001] results in unusual alignment effects. Anisotropic Pr11.5Zr4Co85 powders with coercivity of 4.1 kOe and energy product of 7.2 MGOe were obtained.

  7. Evaluation of the environmental contamination at an abandoned mining site using multivariate statistical techniques--the Rodalquilar (Southern Spain) mining district.

    PubMed

    Bagur, M G; Morales, S; López-Chicano, M

    2009-11-15

    Unsupervised and supervised pattern recognition techniques such as hierarchical cluster analysis, principal component analysis, factor analysis and linear discriminant analysis have been applied to water samples recollected in Rodalquilar mining district (Southern Spain) in order to identify different sources of environmental pollution caused by the abandoned mining industry. The effect of the mining activity on waters was monitored determining the concentration of eleven elements (Mn, Ba, Co, Cu, Zn, As, Cd, Sb, Hg, Au and Pb) by inductively coupled plasma mass spectrometry (ICP-MS). The Box-Cox transformation has been used to transform the data set in normal form in order to minimize the non-normal distribution of the geochemical data. The environmental impact is affected mainly by the mining activity developed in the zone, the acid drainage and finally by the chemical treatment used for the benefit of gold.

  8. A metabolomic study on the biological effects of metal pollutions in oysters Crassostrea sikamea.

    PubMed

    Ji, Chenglong; Wang, Qing; Wu, Huifeng; Tan, Qiaoguo; Wang, Wen-Xiong

    2016-01-15

    Metal pollution has become a great threat to organisms in the estuaries in South China. In the present study, the oysters Crassostrea sikamea were collected from one clean (Jiuzhen) and five metal polluted sites (Baijiao, Fugong, Gongqian, Jinshan and Songyu). The tissue metal concentrations in oysters indicated that the five metal sites were polluted by several metals, including Cr, Ni, Co, Cu, Zn, Ag, Cd and Pb with different patterns. Especially, Cu and Zn were the major contaminants in Baijiao, Fugong and Jinshan sites. The metabolic responses in oysters C. sikamea indicated that the metal pollutions in BJ, FG, JS and SY sites induced disturbances in osmotic regulation and energy metabolism via different metabolic pathways. However, the metal pollution in GQ site mainly influenced the osmotic regulation in the oysters C. sikamea. This study demonstrates that NMR-based metabolomics is useful to characterize metabolic responses induced by metal pollution.

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

    PubMed

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

    2015-01-01

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

  10. Magnetoresistance between oxidized Co-rich particles grown by high current electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Plaza, M.; Perez, L.; Sanchez, M. C.; Fernández-Pacheco, A.; De Teresa, J. M.

    2009-12-01

    In this work, we present Co-rich particles which have been successfully grown by high current electroplating. This technique produces particles with a Co-Cu core surrounded by an oxidized shell. This shell has two consequences: on the one hand, it electrically isolates the magnetic core and acts as a tunnel barrier; on the other hand, the ferromagnetic/antiferromagnetic structure causes an exchange bias coupling when cooling the particles in the presence of magnetic field. We also present magnetoresistance measurements up to 9 T. At low field, direct tunnelling between magnetic cores through the insulating layer properly explains the experimental observations, but, at high field, a linear contribution dominates the MR. The latter behaviour can be understood by assuming second-order tunnelling.

  11. Heavy metals in mullet, Liza abu, and catfish, Silurus triostegus, from the Atatürk Dam Lake (Euphrates), Turkey.

    PubMed

    Karadede, Hülya; Oymak, Seyit Ahmet; Unlü, Erhan

    2004-04-01

    The distribution of some heavy metals in three different organs of mullet, Liza abu, and catfish, Silurus triostegus, from Atatürk Dam Lake located on Euphrates (Turkey) was studied. Co and Mo concentrations were below limits of detection in all fish organs, whereas Ni was also below limits in organs of mullet. The metal accumulation in the liver and gill of L. abu and S. triostegus was found to be quite high in comparison with the muscle. In general, the concentrations are similar to those previously observed on other fish studied in Atatürk Dam Lake and lower than those determined in Tigris River. The analysed metals (Co, Cu, Fe, Mn, Mo, Ni and Zn) were found in fish muscle at mean concentrations under the permissible limits proposed by FAO.

  12. Concentrations of some heavy metals in water, sediment and fish species from the Atatürk Dam Lake (Euphrates), Turkey.

    PubMed

    Karadede, H; Unlü, E

    2000-11-01

    Concentrations of heavy metals (Cd, Co, Cu, Fe, Hg, Mn, Mo, Ni, Pb and Zn) were measured in the water, sediment and fish species (Acanthobrama marmid, Chalcalburnus mossulensis, Chondrostoma regium, Carasobarbus luteus, Capoetta trutta and Cyprinus carpio) from the Atatürk Dam Lake, Turkey. Among the heavy metals studied Cd, Co, Hg, Mo and Pb were not detected in water, sediments and fish samples, while Ni was undetectable levels in fish samples. Levels of Cu, Fe, Mn and Zn varied depending on different tissues. The results of this study indicated that a general absence of serious pollution in the dam lake is due to heavy metals, where as the concentrations of elements found could mainly be attributed to geological sources.

  13. Carbon in the Metal of Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Bashir, N.; Beckett, J. R.; Hutcheon, I. D.; Stolper, E. M.

    1996-03-01

    Magmatic iron meteorites (e.g., group IIIAB) are believed to represent the slowly cooled cores of asteroidal-sized bodies. Concentration gradients of Ni in taenite (gamma-alloy) adjacent to kamacite (alpha-alloy) have been studied extensively following the early work of Wood and Goldstein and Ogilvie, and can be used to constrain the rate at which the meteorite cooled through -700 degrees-400 degrees C. Studies on non-anomalous irons have also shown zoning profiles in C, Co, Cu, Zn, Ga, and Ge. Zoning patterns of elements other than Ni can provide independent constraints on the thermal histories of iron meteorites at lower temperatures, provided as in the case of C, N and P, that the elements diffuse significantly faster than Ni. We report here ion microprobe measurements of the distribution

  14. Trace element uptake by Eleocharis equisetina (spike rush) in an abandoned acid mine tailings pond, northeastern Australia: implications for land and water reclamation in tropical regions.

    PubMed

    Lottermoser, Bernd G; Ashley, Paul M

    2011-10-01

    This study was conducted to determine the uptake of trace elements by the emergent wetland plant species Eleocharis equisetina at the historic Jumna tin processing plant, tropical Australia. The perennial emergent sedge was found growing in acid waters (pH 2.45) and metal-rich tailings (SnAsCuPbZn). E. equisetina displayed a pronounced acid tolerance and tendency to exclude environmentally significant elements (Al, As, Cd, Ce, Co, Cu, Fe, La, Ni, Pb, Se, Th, U, Y, Zn) from its above-substrate biomass. This study demonstrates that geobotanical and biogeochemical examinations of wetland plants at abandoned mined lands of tropical areas can reveal pioneering, metal-excluding macrophytes. Such aquatic macrophytes are of potential use in the remediation of acid mine waters and sulfidic tailings and the reclamation of disturbed acid sulfate soils in subtropical and tropical regions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Bioaccumulation of Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn in trophosome and vestimentum of the tube worm Riftia pachyptila from Guaymas basin, Gulf of California

    NASA Astrophysics Data System (ADS)

    Ruelas-Inzunza, J.; Páez-Osuna, F.; Soto, Luis A.

    2005-07-01

    Twenty two specimens of vestimentiferan tube worms Riftia pachyptila were collected from Guaymas Basin. The distribution of ten trace metals in trophosome and vestimentum was investigated. Highest mean concentrations of Co, Cu and Fe were detected in the trophosome; while higher mean levels of Cd, Hg, Mn, Ni, Pb and Zn were measured in the vestimentum. However, the t-student test resulted in significant differences (p<0.05) only in the case of Co. Cd and Fe concentrations in vestimentum increased accordingly with the size of specimens. With respect to vent fluids, extreme uptake seems to be a characteristic of R. pachyptila in the case of Cu and Zn but not for the rest of the analyzed metals. Studies concerning accumulation mechanisms of trace metals in R. pachyptila are needed, particularly on the capacity of this organism to tolerate elevated levels of elements considered as non-essential.

  16. Polyelemental nanoparticle libraries

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Soil and plant contamination with heavy metals in the area of the old railway junction Tarnowskie Góry and near two main railway routes.

    PubMed

    Malawska, M; Wiłkomirski, B

    2000-01-01

    Heavy metals (Pb, Cd, Cr, Hg, Mo, Zn, Co, Cu) content was determined in soil and plant samples collected in the different areas of the railway junction Tarnowskie Góry, as well as, near two main railway routes, i.e. Warsaw-Gdańsk and Katowice-Gdynia. In Tarnowskie Góry soil and plant samples were collected in four functional parts of the junction, i.e. the rolling stock cleaning bay, platform area, railway siding and loading ramp. It was found that the contamination of soil and plants by heavy metal was the highest in loading ramp. A particularly high pollution level of copper was observed. The contamination level near the railway routes decreased accordingly to the distance from routes which suggests pollutant role of railway transport.

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

    SciTech Connect

    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

  1. First-principles determination of magnetic properties

    NASA Astrophysics Data System (ADS)

    Wu, Ruqian; Yang, Zongxian; Hong, Jisang

    2003-02-01

    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.

  2. Dual function armchair graphene nanoribbon-based spin-photodetector: Optical spin-valve and light helicity detector

    SciTech Connect

    Ostovari, Fatemeh; Moravvej-Farshi, Mohammad Kazem

    2014-08-18

    We show an armchair graphene nanoribbon channel connected between asymmetric ferromagnetic source-drain structure—i.e., p-type Co/Au/graphene source and n-type Co/Cu/graphene drain—can operate as dual function spin-photodetector, under zero external biases at room temperature. It can function as an optical spin-valve with magnetoresistance of greater than 60% and responsivity as high as 25.12 A/mW, when irradiated by an un-polarized light of energy ∼3.03 eV. Under a circularly polarized illumination, this optical spin-valve can also operate as a light helicity detector. The calculated magnetoresistances for right and left circularly polarized lights are both greater than 60%.

  3. Synthesis, characterization and conductivity studies of ZnFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Narsimulu, D.; Venkateswarlu, M.; Satyanarayana, N.

    2015-06-01

    Transition metal ferrites with general formula AB2O4 (A=Co, Cu, Mn, Zn, B=Fe+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 ZnFe2O4 with cubic spinel structured material was prepared by acrylamide assisted citrate combustion process. Phase, structural coordination and thermal behavior of the prepared ZnFe2O4 were confirmed by powder X-ray diffraction, FTIR spectra and TG/DTA thermogram respectively. Morphology and specific surface area of the ZnFe2O4 were identified by SEM and BET surface analyzer respectively and its conductivity studies were made through impedance spectroscopy.

  4. Classification of Antarctic algae by applying Kohonen neural network with 14 elements determined by inductively coupled plasma optical emission spectrometry

    NASA Astrophysics Data System (ADS)

    Balbinot, L.; Smichowski, P.; Farias, S.; Arruda, M. A. Z.; Vodopivez, C.; Poppi, R. J.

    2005-06-01

    Optical emission spectrometers can generate results, which sometimes are not easy to interpret, mainly when the analyses involve classifications. To make simultaneous data interpretation possible, the Kohonen neural network is used to classify different Antarctic algae according to their taxonomic groups from the determination of 14 analytes. The Kohonen neural network architecture used was 5×5 neurons, thus reducing 14-dimension input data to two-dimensional space. The input data were 14 analytes (As, Co, Cu, Fe, Mn, Sr, Zn, Cd, Cr, Mo, Ni, Pb, Se, V) with their concentrations, determined by inductively coupled plasma optical emission spectrometry in 11 different species of algae. Three taxonomic groups ( Rhodophyta, Phaeophyta and Cholorophyta) can be differentiated and classified through only their Cu content.

  5. Porous Co3O4/CuO composite assembled from nanosheets as high-performance anodes for lithium-ion batteries.

    PubMed

    Hao, Qin; Zhao, Dianyun; Duan, Huimei; Xu, Caixia

    2015-04-24

    Upon dealloying a carefully designed CoCuAl ternary alloy in NaOH solution at room temperature, a Co3 O4 /CuO nanocomposite with an interconnected porous microstructure assembled by a secondary structure of nanosheets was successfully fabricated. By using the dealloying strategy, the target metals directly grew to form uniform bimetallic oxide nanocomposites. Owing to the unique hierarchical structure and the synergistic effect of both active electrode materials, the Co3 O4 /CuO nanocomposite exhibits much enhanced electrochemical performance with higher capacities and better cycling stability compared to anodes of pure Co3 O4 . Moreover, it performs excellently in terms of cycle reversibility, Coulombic efficiency, and rate capability, at both low or high current rates. With the advantages of unique performance and ease of preparation, the as-made Co3 O4 /CuO nanocomposite demonstrates promising application potential as an advanced anode material for lithium-ion batteries.

  6. Structural, electronic, and magnetic properties in transition-metal-doped arsenene: Ab initio study

    NASA Astrophysics Data System (ADS)

    Luo, Min; Hao Shen, Yu; Yin, Tai Ling

    2017-01-01

    The structural, electronic and magnetic properties of arsenene doped with five different transition-metal (TM) atoms (TM = Co, Cu, Mn, Fe, and Ni) are investigated using the density functional theory. Magnetism is observed in the cases of Cu, Mn, Fe, and Ni. Among these four magnetic systems, the Ni-doped system is the most easily formed. Hence, we study the ferromagnetic (FM) interaction in two-Ni-doped arsenene. It is found that the p-d hybridization mechanism results in the ferromagnetic state. However, the FM interaction is obviously depressed by the increasing Ni-Ni distance, which could be well explained by the Zener-Ruderman-Kittel-Kasuya-Yosida (RKKY) theory. Moreover, exotic phenomena appear in the two-Mn-doped system. Both nonmagnetic and ferromagnetic states are observed.

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

    PubMed

    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. 2010 Elsevier B.V. All rights reserved.

  8. Potential bioavailability assessment, source apportionment and ecological risk of heavy metals in the sediment of Brisbane River estuary, Australia.

    PubMed

    Duodu, Godfred Odame; Goonetilleke, Ashantha; Ayoko, Godwin A

    2017-02-12

    A weak acid extraction was used to mobilize the loosely bound metals in estuary sediment samples. More than 30% of Ag, As, Ca, Cd, Co, Cu, Hg, Mn Ni, Pb and Zn were leached from the sediment showing that these metals are significantly present in the bioavailable form. PCA/APCS identified three sources of the metals, namely: lithogenic accounting for 72%, shipping related contributing 15% and traffic related representing 13% of the total load. Application of pollution index (PI) and modified pollution index (MPI) revealed that the sediment range from unpolluted to heavily polluted while ecological risk index (RI) classifies the sediment as posing low ecological risk modified ecological risk index (MRI) suggests considerable to very high ecological risk. To provide holistic insights into the ecological risks posed by metals, enrichment factor, MPI and MRI are recommended for the assessment of sediment in complex environments such as estuaries.

  9. Heavy metals in the bottom sediments of the Furo of Laura estuary, Eastern Amazon, Brazil.

    PubMed

    Lima, M W; Santos, M L S; Faial, K C F; Freitas, E S; Lima, M O; Pereira, J A R; Cunha, I P R T

    2017-05-15

    The Furo of Laura is an economically important river in the Amazon estuary. Thus, in the present study, we evaluated the metal distribution (Al, Cd, Co, Cu, Cr, Fe, Ni, and Mg) in the bottom sediments of this river. The sediments were sampled at four points every 2months for a year with an Ekman-Birge sampler. After microwave acid digestion, the metal levels were determined by optical emission spectrometry with inductively coupled plasma. The particle size and organic matter content influenced the concentration of the metals. The sediments were not enriched by the analyzed metals; the estuary therefore retained the characteristics of an uncontaminated environment, thus serving as a reference environment for comparison. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Atomistic Modeling of Nanostructures via the BFS Quantum Approximate Method

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Garces, Jorge E.; Noebe, Ronald D.; Farias, D.

    2003-01-01

    Ideally, computational modeling techniques for nanoscopic physics would be able to perform free of limitations on the type and number of elements, while providing comparable accuracy when dealing with bulk or surface problems. Computational efficiency is also desirable, if not mandatory, for properly dealing with the complexity of typical nano-strucured systems. A quantum approximate technique, the BFS method for alloys, which attempts to meet these demands, is introduced for the calculation of the energetics of nanostructures. The versatility of the technique is demonstrated through analysis of diverse systems, including multi-phase precipitation in a five element Ni-Al-Ti-Cr-Cu alloy and the formation of mixed composition Co-Cu islands on a metallic Cu(III) substrate.

  11. Mapping the Copper energy band using the quantum well states

    NASA Astrophysics Data System (ADS)

    Wu, J.; Choi, J.; Owens, T.; Qiu, Z. Q.; Rotenberg, E.; Smith, N. V.

    2006-03-01

    Quantum well states (QWS) of copper electrons in Cu/Co/Cu(100) system are investigated using Angle Resolved Photoemission Electron Spectroscopy (ARPES). The samples were grown epitaxially at room temperature and measured in situ at beamlime 7 of the Advanced Light Source (ALS). Photoemission intensity oscillates with both the electron energy and the Cu film thickness. By counting the thickness oscillation periodicity at a given energy, we can determine the out-of-plane electron momentum without the need of the phase value in the phase accumulation model. This allows the experimental determination of the E-k relation (energy band) for the Cu film. We here report the Cu energy band determined in this way at different in-plane momentum. In addition, by fitting the oscillation as a function of the Cu thickness, we also determined the phase value of the quantization condition as a function of the energy and in-plane momentum.

  12. Atomistic modelling of nanostructures via the Bozzolo Ferrante Smith quantum approximate method

    NASA Astrophysics Data System (ADS)

    Bozzolo, Guillermo; Garcés, Jorge E.; Noebe, Ronald D.; Farías, Daniel

    2003-09-01

    Ideally, computational modelling techniques for nanoscopic physics would be able to perform free of limitations on the type and number of elements, while providing comparable accuracy when dealing with bulk or surface problems. Computational efficiency is also desirable, if not mandatory, for properly dealing with the complexity of typical nanostructured systems. A quantum approximate technique, the Bozzolo-Ferrante-Smith method for alloys, which attempts to meet these demands, is introduced for calculation of the energetics of nanostructures. The versatility of the technique is demonstrated through analysis of diverse systems, including multiphase precipitation in a five-element Ni-Al-Ti-Cr-Cu alloy and the formation of mixed composition Co-Cu islands on a metallic Cu(111) substrate.

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Popescu, Voicu; Kratzer, Peter

    2013-09-01

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

  15. Structural, electronic, and magnetic properties of transition metal doped ReS2 monolayer

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    Magnetic properties of transition-metal (TM) atoms (TM=Co, Cu, Mn, Fe, and Ni) doped ReS2 monolayer are investigated by first-principles calculations. It is found that magnetism appears in the cases of Co, Fe, and Ni. Among all the samples, the Co-doped system has the largest magnetic moment. Therefore, we further study the interaction in the two-Co-doped system. Our results show that the interaction between two Co atoms is always ferromagnetic (FM), but such FM interaction is obviously depressed by the increasing Co-Co distance, which is well described by a simple Heisenberg model based on the Zener theory. Our results provide useful insight for promising applications of TM-doped ReS2 monolayer in the future.

  16. Analysis of trace metals in water by inductively coupled plasma emission spectrometry using sodium dibenzyldithiocarbamate for preconcentration

    USGS Publications Warehouse

    Smith, C.L.; Motooka, J.M.; Willson, W.R.

    1984-01-01

    Since concentrations of trace elements in most natural waters seldom exceed the ??g/L level, analysis of trace elements in natural waters by inductively coupled plasma emission spectrometry (ICP) requires a preconcentration procedure. The elements Ag, Bi, Cd, Co, Cu, Fe, Mo, Ni, Pb, Sn, V, W, and Zn were separated and concentrated from 500 mL of water by coprecipitating them with sodium dibenzyldithiocarbamate (NaDBDTC) using nickel or silver as a carrier. The precipitated trace elements were collected on a membrane filter, redissolved from the filter with hot nitric and hydrochloric acids, and analyzed using ICP. Recoveries for all the trace elements except tungsten exceeded 80%. Coprecipitation of trace elements with NaDBDTC eliminated the use of difficult-to-inject organic solvents, and NaDBDTC coprecipitated a wider array of trace elements than ammoniumpyrrolidinedithiocarbamate (APDC), another commonly used coprecipitate.

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

    PubMed

    Nicolaides, Antonis; Soulimane, Tewfik; Varotsis, Constantinos

    2016-09-01

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

  18. Too much is bad--an appraisal of phytotoxicity of elevated plant-beneficial heavy metal ions.

    PubMed

    Anjum, Naser A; Singh, Harminder P; Khan, M Iqbal R; Masood, Asim; Per, Tasir S; Negi, Asha; Batish, Daizy R; Khan, Nafees A; Duarte, Armando C; Pereira, Eduarda; Ahmad, Iqbal

    2015-03-01

    Heavy metal ions such as cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn) are considered essential/beneficial for optimal plant growth, development, and productivity. However, these ions readily impact functions of many enzymes and proteins, halt metabolism, and exhibit phytotoxicity at supra-optimum supply. Nevertheless, the concentrations of these heavy metal ions are increasing in agricultural soils worldwide via both natural and anthropogenic sources that need immediate attention. Considering recent breakthroughs on Co, Cu, Fe, Mn, Mo, Ni, and Zn in soil-plant system, the present paper: (a) overviews the status in soils and their uptake, transport, and significance in plants; (b) critically discusses their elevated level-mediated toxicity to both plant growth/development and cell/genome; (c) briefly cross talks on the significance of potential interactions between previous plant-beneficial heavy metal ions in plants; and (d) highlights so far unexplored aspects in the current context.

  19. Physicochemical Analysis of Indicator Lichens as a Component of Conservation Area Baseline Monitoring

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    The gross and average contents of 15 metals (Al, As, Cd, Co, Cu, Ge, Fe, Mn, Mo, Ni, Pb, Sn, Ti, V, and Zn) in samples of Hypogymnia physodes collected from a reserve area in Tver Region were determined using inductively-coupled plasma atomic emission spectroscopy (ICP-AES). Apparently, most of these elements appeared as a result of transboundary transfer. Their concentration in lichens depended on the atmospheric humidity. An excess of moisture in ecotopes located near rivers and swamps increased the gross concentration of separate elements in the lichens. The average contents of most elements in the specimens were within permissible limits, which allowed possible baseline element concentration ranges for this region to be established.

  20. Kondo effect in CoxCu1-x granular alloys prepared by chemical reduction method

    NASA Astrophysics Data System (ADS)

    Dhara, Susmita; Chowdhury, Rajeswari Roy; Bandyopadhyay, Bilwadal

    2015-06-01

    Nanostructured CoCu granular alloys CoxCu1-x (x ≤ 0.3) have been prepared by chemical reduction method using NaBH4 as a reducing agent. Electronic transport properties are studied in the temperature range 4-300 K. Resistance exhibits a metallic behavior below room temperature and draws a minimum near 20 K in all the samples except in Co0.3Cu0.7. This low temperature resistivity minimum diminishes with applied magnetic field. There is also a logarithmic temperature dependence of resistivity at temperatures below 20 K. This phenomenon indicates a Kondo-like scattering mechanism involving magnetic Co impurity spin clusters in Cu host.

  1. Kondo effect in Co{sub x}Cu{sub 1-x} granular alloys prepared by chemical reduction method

    SciTech Connect

    Dhara, Susmita Chowdhury, Rajeswari Roy; Bandyopadhyay, Bilwadal

    2015-06-24

    Nanostructured CoCu granular alloys Co{sub x}Cu{sub 1-x} (x ≤ 0.3) have been prepared by chemical reduction method using NaBH{sub 4} as a reducing agent. Electronic transport properties are studied in the temperature range 4-300 K. Resistance exhibits a metallic behavior below room temperature and draws a minimum near 20 K in all the samples except in Co{sub 0.3}Cu{sub 0.7}. This low temperature resistivity minimum diminishes with applied magnetic field. There is also a logarithmic temperature dependence of resistivity at temperatures below 20 K. This phenomenon indicates a Kondo-like scattering mechanism involving magnetic Co impurity spin clusters in Cu host.

  2. Effect on photophysical properties of colloidal ZnS quantum dots by doping with cobalt, copper, and cobalt-copper mixtures

    NASA Astrophysics Data System (ADS)

    Iqbal, Muhammad Javed; Iftekhar, Maryam

    2011-05-01

    Colloidal ZnS quantum dots (QDs) are prepared by passing H2S gas through a solution of Zn(CH3COO)2 in acetonitrile. Photophysical properties are investigated using UV-Visible and photoluminescence (PL) spectroscopy. The spectrum shows an absorption shoulder at 271 nm representing a band gap of 4.6 eV. The doping of ZnS QDs with Co, Cu, and a mixture of Co and Cu not only increased the band gap to 0.2 eV but also turns these otherwise colorless QDs to blue in color due to cobalt, and green due to Cu. The observed emission in the visible region suggests that the dopants may have induced additional excited states to the ZnS QDs. This absorbance in the visible region can be utilized in the optoelectronic applications.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Single spin-torque vortex oscillator using combined bottom-up approach and e-beam lithography

    NASA Astrophysics Data System (ADS)

    Abreu Araujo, F.; Piraux, L.; Antohe, V. A.; Cros, V.; Gence, L.

    2013-06-01

    A combined bottom-up assembly of electrodeposited nanowires and electron beam lithography technique has been developed to investigate the spin transfer torque and microwave emission on specially designed nanowires containing a single Co/Cu/Co pseudo spin valve. Microwave signals have been obtained even at zero magnetic field. Interestingly, high frequency vs. magnetic field tunability was demonstrated, in the range 0.4-2 MHz/Oe, depending on the orientation of the applied magnetic field relative to the magnetic layers of the pseudo spin valve. The frequency values and the emitted signal frequency as a function of the external magnetic field are in good quantitative agreement with the analytical vortex model as well as with micromagnetic simulations.

  5. Electrochemical synthesis of highly ordered magnetic multilayered nanowire arrays

    NASA Astrophysics Data System (ADS)

    Kok, Kuan-Ying; Ng, Inn-Khuan; Saidin, Nur Ubaidah; Zali, Nurazila Mat; Bustamam, Farah Khuwailah Ahmad; Shaari, Abdul Halim

    2012-06-01

    Electrochemical deposition is a versatile technique that has been employed to synthesize various types of onedimensional nanostructures such as nanorods, nanotubes and nanowires to meet different requirements for applications. Magnetic nanowires in the form of multilayered structures, such as Co/Cu and permalloy (Ni80Fe20)/Cu, with ferromagnetic materials alternating with non-magnetic materials exhibit giant magnetoresistance (GMR) property that can be utilized in sensors and mass memory devices. This study focuses on the synthesis of highly ordered magnetic multilayered nanowire arrays using template-directed electrochemical deposition technique. The nanowires were electrodeposited within the nanopores of anodized alumina from sulphate baths via pulse potential technique. The structures and compositions of the wires were characterized using various microscopy and probe-based techniques. Magnetoresistance measurement was performed on the multilayered nanowire arrays.

  6. [Vegetation stress spectra and their relations with the contents of metal elements within the plant leaves in metal mines in Heilongjiang].

    PubMed

    Chen, Sheng-bo; Zhou, Chao; Wang, Jin-nian

    2012-05-01

    In this paper, Duobao Mt. and Tong Mt. were taken as examples. The spectra of the crown or leaf of the vegetation were collected. Fourteen metal elements in the rock, soil (A, B, C) and vegetation (root, trunk, leaf), and biological chemical parameters were measured. It was indicated that different metal elements were selected and enriched in different vegetation. The red edge position (REP) and the absorbing depth are related to biological chemical parameters. A multivariable regression equation was built between the absorption depths and the contents of metal elements. The relative coefficients between the absorbing depths and chemical elements, including Co, Cu, N, Mo, Ag, Sb, W, Pb and As, are greater than 0.75. Thus, it is important to analyze and measure the contents of metal elements by hyper-spectral remote sensing of vegetation stress spectrum.

  7. [Xenoestrogens: endocrine disrupting compounds].

    PubMed

    Wozniak, Milena; Murias, Marek

    2008-11-01

    In recent years much attention has been paid to the issues of chemicals that disrupt the normal function of endocrine system, namely xenoestrogens. These chemicals can mimic the activity of endogenous estrogens, antagonize their interaction with estrogen receptors or disrupt the synthesis, metabolism and functions of endogenous female hormones. Due to the fact that they act thanks to many different mechanisms, it is very difficult to estimate their estrogenic activity by means of a simple tests. The important issue remains the fact that xenoestrogens may have a positive or negative influence on the function of the endocrine system. It seems to be very important that there are many sources of xenoestrogens, that is not only vegetables and fruit (phytoestrogens), but also metals (Co, Cu, Ni, Cr, Pb), dental appliances (alkilphenols), food containers or blood containers (PVC--polyvinyl chloride, DEHP--di-(2-ethylhexyl) phthalate), cosmetics (parabens) and pesticides (DDT--dichlor-diphenyl-trichlorethylane, endosulfane).

  8. Giant magnetic coercivity in CaCu5-type SmNi3TSi (T=Mn-Cu) solid solutions

    NASA Astrophysics Data System (ADS)

    Yao, Jinlei; Yan, Xu; Morozkin, A. V.

    2015-12-01

    The effects of transition metal substitution for Ni on the magnetic properties of the CaCu5-type SmNi3TSi (T=Mn, Fe, Co, Cu) solid solutions have been investigated. SmNi3MnSi, SmNi3FeSi, SmNi3CoSi and SmNi3CuSi 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 SmNi3TSi (T=Mn, Fe, Co, Cu) were calculated in terms of isothermal magnetic entropy change (ΔSm). The magnetic entropy ΔSm reaches value of -1.1 J/kg K at 130 K for SmNi3MnSi, -0.4 J/kg K at 180 K for SmNi3FeSi, -0.37 J/kg K at 45 K for SmNi3CoSi and -0.5 J/kg K at 12 K for SmNi3CuSi in field change of 0-50 kOe around the ferromagnetic ordering temperature. They show positive ΔSm of +2.4 J/kg K at 30 K for SmNi3MnSi, -2.6 J/kg K at 65 K for SmNi3FeSi, +0.73 J/kg K at 15 K for SmNi3CoSi and -0.5 J/kg K at 6 K for SmNi3CuSi in field change of 0-50 kOe around the metamagnetic-like transition temperature. Below the field induced transition temperature, SmNi3TSi (T=Mn, Fe, Co, Cu) exhibits giant magnetic coercivity of 80 kOe at 20 K for SmNi3MnSi, 87 kOe at 40 K for SmNi3FeSi, 27 kOe at 20 K for SmNi3CoSi and 54 kOe at 5 K for SmNi3CuSi. Below the field induced transition temperature, SmNi3TSi (T=Mn, Fe, Co, Cu) exhibits giant magnetic coercivity of 80 kOe at 20 K for SmNi3MnSi, 87 kOe at 40 K for SmNi3FeSi, 27 kOe at 20 K for SmNi3CoSi and 54 kOe at 5 K for SmNi3CuSi.

  9. Acute toxicity assessment of Polish (waste) water with a microplate-based Hydra attenuata assay: a comparison with the Microtox test.

    PubMed

    Pardos, M; Benninghoff, C; Guéguen, C; Thomas, R; Dobrowolski, J; Dominik, J

    1999-12-15

    The use of Hydra attenuata in acute toxicity assessment is a potentially useful tool in (waste) water biomonitoring. The purpose of this study was to compare the sensitivity of H. attenuata with the extensively used Microtox test on 14 (waste) water samples from the Kraków region (South Poland). To this end, specific morphological changes displayed by the freshwater cnidarian Hydra attenuata (lethal LC50s and sublethal EC50s effects) and bioluminescence of the marine bacteria Vibrio fisheri (Microtox) were compared. Clearly, the Hydra assay was the more sensitive indicator of toxicity. No relationship was found among Hydra toxicological responses and water levels of As, Cd, Co, Cu, Pb and Zn. However, it appeared that toxicity to Hydra might be due to ammonia levels. Additional studies to better circumscribe the tolerance of H. attenuata to 'natural' water characteristics are needed.

  10. Mixed polyanion glass cathodes: Glass-state conversion reactions

    SciTech Connect

    Kercher, Andrew K.; Kolopus, James A.; Carroll, Kyler; Unocic, Raymond R.; Kirklin, S.; Wolverton, C.; Stooksbury, Shelby L.; Boatner, Lynn A.; Dudney, Nancy J.

    2015-01-01

    Mixed polyanion (MP) glasses can undergo glass-state conversion (GSC) reactions to provide an alternate class of high-capacity cathode materials. GSC reactions have been demonstrated in phosphate/vanadate glasses with Ag, Co, Cu, Fe, and Ni cations. These MP glasses provided high capacity and good high power performance, but suffer from moderate voltages, large voltage hysteresis, and significant capacity fade with cycling. Details of the GSC reaction have been revealed by x-ray absorption spectroscopy, electron microscopy, and energy dispersive x-ray spectroscopy of ex situ cathodes at key states of charge. Using the Open Quantum Materials Database (OQMD), a computational thermodynamic model has been developed to predict the near-equilibrium voltages of glass-state conversion reactions in MP glasses.

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

    PubMed

    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.

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

    PubMed

    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.

  13. Magnesium silicide intermetallic alloys

    NASA Astrophysics Data System (ADS)

    Li, Gh.; Gill, H. S.; Varin, R. A.

    1993-11-01

    Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not exceeding 1105 °C ± 5 °C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg2Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg2Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg2Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg2Si matrix were found in the Mg2Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

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

    PubMed

    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.

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

    PubMed

    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.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Trends of labile trace metals in tropical urban water under highly contrasted weather conditions.

    PubMed

    Villanueva, J D; Le Coustumer, P; Denis, A; Abuyan, R; Huneau, F; Motelica-Heino, M; Peyraube, N; Celle-Jeanton, H; Perez, T R; Espaldon, M V O

    2015-09-01

    The spatio-temporal trend of trace metals (Cd, Co, Cr, Cu, Ni, Pb, and Zn) in a tropical urban estuary under the influence of monsoon was determined using diffusive gradient in thin films (DGT) in situ samplers. Three different climatic periods were observed: period 1, dry with dredging activity; period 2, intermediate meaning from dry to wet event; and period 3, wet having continuous rainfall. Conforming to monsoon regimes, these periods correspond to the following: transition from winter to summer, winter, and summer monsoons, respectively. The distinction of each period is defined by their specific hydrological and physico-chemical conditions. Substantial concentrations of the trace metals were detected. The distribution and trend of the trace metals under the challenge of a tropical climate were able to follow using DGT as a sensitive in situ sampler. In order to identify the differences among periods, statistical analyses were performed. This allowed discriminating period 2 (oxic water) as significantly different compared to other periods. The spatio-temporal analysis was then applied in order to distinguish the trend of the trace metals. Results showed that the trend of trace metals can be described according to their response to (i) seasonal variations (Cd and Cr), (ii) spatio-temporal conditions (Co, Cu, Ni, and Pb), and (iii) neither (i) nor (ii) meaning exhibiting no response or having constant change (Zn). The correlation of the trace metals and the physico-chemical parameters reveals that Cd, Co, Cu, and Cr are proportional to the dissolved oxygen (DO), Cd and Ni are correlated pH, and Zn lightly influenced by salinity.

  1. Evaluation of the DGT technique for selective measurement of aluminium and trace metal concentrations in an acid drainage-impacted coastal waterway.

    PubMed

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

    2017-05-24

    The performance of DGT-Chelex, DGT-Metsorb and DGT-MBL (Chelex-Metsorb mixed binding layer) with open and restricted diffusive layers for trace metal (Al, Cd, Co, Cu, Mn, Ni, Pb, Zn) and oxyanion (As, Mo, Sb, V) measurements, was evaluated in four natural waters with different pH (range 3.29-7.81). In moderately acidic (pH ≈ 5) and circumneutral (pH ≈ 6.3) waters, all three binding layers measured relatively similar concentrations of Al, while in more alkaline waters (pH ≈ 8) DGT-MBL measured higher concentrations than the other two binding layers. The measurements of DGT-Chelex and DGT-MBL for Co, Cu, Ni, Pb and Zn, and DGT-Metsorb and DGT-MBL for As, Sb and V were within 82-119% and not statistically different (p > 0.05) over the pH range 5-8. Mn measurements by DGT-Chelex and DGT-MBL were quite similar (95%) at pH 6.3, while DGT-MBL measured higher concentrations than DGT-Chelex at other pHs. The ratios of measured concentrations with different diffusive layers (Crestricted/Copen) were between 0.78 and 1.12 for all binding layers and no statistical differences (p > 0.05) were observed, except for Al at pH 7.81 and Cu at pH 6.28. DGT-MBL was comparable to DGT-Chelex for the measurement of most trace metals, and to DGT-Metsorb for the measurement of most oxyanions, over the pH range 5.05-7.81. Overall, DGT-MBL is superior to the other tested binding layers because it can simultaneously measure cations and anions, and accurately measure dissolved Al, across the greatest range of environmental conditions.

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

    PubMed

    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).

  3. First-Principles Calculation of the Structural, Magnetic, and Electronic Properties of the CoxCu1-x Solid Solutions Using Special Quasirandom Structures

    NASA Astrophysics Data System (ADS)

    Kong, Yi; Liu, Baixin

    2007-02-01

    We investigate, in the present study, the structural properties, magnetic moments and charge distribution of the solid solution in an immiscible Co-Cu system at equilibrium by first-principles calculation using special quasirandom structures (SQS). In order to mimic the pair and multisite correlation functions of the randomly substitutional fcc solid solutions, the original SQS is developed to include five 16-atom SQS unit cells, i.e., 1/16, 2/16, 3/16, 4/16, and 8/16, enabling to mimic at nine specific alloys compositions. Correspondingly, a new error analysis method is proposed for comparing the situations of various alloy compositions within the SQS unit cells having a same number of atoms. The developed SQS are then applied in the first-principles calculation to study the CoxCu1-x solid solutions (x refers to the Co concentration). It turns out that the calculated results of the lattice constants and magnetic moments versus the Co concentration are in good agreement with the experimental data, and especially, the sharp drop in the magnetic moment near the composition x=0.1 is well reproduced. The heats of formation are also calculated and in good agreement with those obtained from Mediema’s thermodynamic theory and available experimental data. At the alloy compositions x=0.25 and 0.75, some hypothetical crystalline structures of the Co-Cu compounds are respectively calculated and their heats of formation are found to be higher than the solid solution counterparts. Finally, the electron distribution among the atoms in the CoxCu1-x solid solutions is studied and the obtained charge densities show that in the CoxCu1-x solid solutions, the charge distributes mostly between the Co-Co atoms, thus forming attractive covalent bonding.

  4. Impact of Ficoll density gradient centrifugation on major and trace element concentrations in erythrocytes and blood plasma.

    PubMed

    Lu, Ying; Ahmed, Sultan; Harari, Florencia; Vahter, Marie

    2015-01-01

    Ficoll density gradient centrifugation is widely used to separate cellular components of human blood. We evaluated the suitability to use erythrocytes and blood plasma obtained from Ficoll centrifugation for assessment of elemental concentrations. We determined 22 elements (from Li to U) in erythrocytes and blood plasma separated by direct or Ficoll density gradient centrifugation, using inductively coupled plasma mass spectrometry. Compared with erythrocytes and blood plasma separated by direct centrifugation, those separated by Ficoll had highly elevated iodine and Ba concentration, due to the contamination from the Ficoll-Paque medium, and about twice as high concentrations of Sr and Mo in erythrocytes. On the other hand, the concentrations of Ca in erythrocytes and plasma were markedly reduced by the Ficoll separation, to some extent also Li, Co, Cu, and U. The reduced concentrations were probably due to EDTA, a chelator present in the Ficoll medium. Arsenic concentrations seemed to be lowered by Ficoll, probably in a species-specific manner. The concentrations of Mg, P, S, K, Fe, Zn, Se, Rb, and Cs were not affected in the erythrocytes, but decreased in plasma. Concentrations of Mn, Cd, and Pb were not affected in erythrocytes, but in plasma affected by EDTA and/or pre-analytical contamination. Ficoll separation changed the concentrations of Li, Ca, Co, Cu, As, Mo, I, Ba, and U in erythrocytes and blood plasma, Sr in erythrocytes, and Mg, P, S, K, Fe, Zn, Se, Rb and Cs in blood plasma, to an extent that will invalidate evaluation of deficiencies or excess intakes. Copyright © 2014 Elsevier GmbH. All rights reserved.

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

    PubMed

    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.

  6. The use of tree barks and human fingernails for monitoring metal levels in urban areas of different population densities of Porto Alegre, Brazil.

    PubMed

    da Silveira Fleck, Alan; Carneiro, Maria Fernanda Hornos; Barbosa, Fernando; Amantea, Sergio Luis; Rhoden, Claudia Ramos

    2017-01-01

    The aim of this study was to evaluate the use of tree barks as a bioindicator of atmospheric pollution in areas of contrasting population densities and to associate the levels of elements found in this bioindicator with those obtained in fingernail samples collected from students living in the same study areas. Tree bark samples were collected from urban areas near highways in regions with high (Area A), intermediate (Area B), and low (Area C) population densities of Porto Alegre, Brazil, and evaluated for chemical elements concentration. Since these areas also differed in traffic density, NO2 was measured by passive sampling. For a comparative purpose, the elements were also determined in fingernail samples collected from students living in the same areas. Accumulated elements were determined by inductively coupled plasma mass spectrometry (ICP-MS) and principal component analysis (PCA) was used as a tool in exploratory data analysis to identify possible sources. We found that Ba, Cd, Co, Cu, Mg, Mn, Ni, Pb, Sb, Sr, V, and Zn were at higher concentrations in tree barks in Area A, while Cd, Co, Cu, Mg, Mn, Ni, and Sr were at higher levels in students' fingernails of Area A as well. Furthermore, concentrations of elements found in barks were associated with those identified in fingernails collected from students living in the same areas. PCA demonstrated that vehicular traffic explained 66.4 % of the variance in tree bark and 50.8 % of the variance in fingernails. NO2 levels were significantly different among the areas, what is consistent with their respective vehicular flow and population density. In conclusion, we found conformance of elements levels accumulated in barks and fingernails at three monitoring areas with different profiles. The amount of traffic-related elements accumulated appears to be associated with the degree of urbanization and vehicular flow. Overall, data suggests a relationship between fingernails and tree bark as bioindicators of exposure

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

    SciTech Connect

    Bhoomeeswaran, H.; Sabareesan, P.

    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).

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Titanium-Substituted Sm-Co High-Temperature Permanent Magnets

    NASA Astrophysics Data System (ADS)

    Zhou, J.; Tang, H.; Skomski, R.; Liu, J. P.; Hadjipanayis, G. C.; Sellmyer, D. J.

    2000-03-01

    A novel magnetic material with a positive temperature coefficient of coercivity and an appreciable high-temperature coercivity of 7.3 kOe at 500 ^oC is reported in Sm-Co-Cu-Ti alloys. Samples with different compositions are prepared by arc-melting. M-T measurement and X-ray diffraction indicate that after suitable heat treatment the samples are two-phase mixtures of 1:5 and 2:17 structures. The coercivity of bulk SmCo_6.1Cu_0.6Ti_0.3 increases from 3.9 kOe at 27 ^oC to a maximum 7.3 kOe at 500 ^oC, and then drops to 6.7 kOe at 550 ^oC. Samples with other compositions exhibit a similar behavior, or a zero temperature coefficient over a broad range of temperature. The anomalous temperature dependence of the coercivity reflects the microstructure of the two-phase magnet. The coercivity of the 2:17/1:5 heterostructures is pinning controlled and exhibits a strong dependence on microstructural details such as the size and geometry of the 2:17 and 1:5 regions. The temperature dependence of the coercivity is explained by the temperature dependence of the domain-wall energy, which affects the curvature of the walls and the pinning behavior. These results show Sm-Co-Cu-Ti alloys to be promising permanent magnets for high-temperature applications. Supported by AFOSR under grant F49620-98-1-0098 and DARPA under ARO grant DAAG 55-98-1-0268.

  10. 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.

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  12. Trace elements release from volcanic ash to seawater. Natural concentrations in Central Mediterranean sea

    NASA Astrophysics Data System (ADS)

    Randazzo, L. A.; Censi, P.; Saiano, F.; Zuddas, P.; Aricò, P.; Mazzola, S.

    2009-04-01

    Distributions and concentrations of many minor and trace elements in epicontinental basins, as Mediterranean Sea, are mainly driven to atmospheric fallout from surroundings. This mechanism supplies an estimated yearly flux of about 1000 kg km-2 of terrigenous matter of different nature on the whole Mediterranean basin. Dissolution of these materials and processes occurring at solid-liquid interface along the water column drive the distributions of many trace elements as V, Cr, Mn, Co, Cu, and Pb with contents ranging from pmol l-1 (Co, Cd, Pb) to nmol l-1 scale in Mediterranean seawater, with some local differences in the basin. The unwinding of an oceanographic cruise in the coastal waters of Ionian Sea during the Etna's eruptive activity in summer 2001 led to the almost unique chance to test the effects of large delivery of volcanic ash to a coastal sea water system through the analyses of distribution of selected trace elements along several seawater columns. The collection of these waters and their analyses about V, Cr, Mn, Co, Cu, and Pb contents evidenced trace element concentrations were always higher (about 1 order of magnitude at least) than those measured concentrations in the recent past in Mediterranean seawater, apart from Pb. Progressive increase of concentrations of some elements with depth, sometimes changing in a "conservative" behaviour without any clear reason and the observed higher concentrations required an investigation about interaction processes occurring at solid-liquid interface between volcanic ash and seawater along water columns. This investigation involving kinetic evaluation of trace element leaching to seawater, was carried out during a 6 months time period under laboratory conditions. X-ray investigations, SEM-EDS observations and analyses on freshly-erupted volcanic ash evidenced formation of alteration clay minerals onto glass fraction surfaces. Chemical analyses carried out on coexisting liquid phase demonstrated that trace

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

    PubMed

    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

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

    PubMed

    Rodriguez, J H; Klumpp, A; Fangmeier, A; Pignata, M L

    2011-03-15

    The carbon dioxide (CO(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(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(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(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(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(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(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 health. Copyright © 2010

  15. Total Contents and Sequential Extraction of Heavy Metals in Soils Irrigated with Wastewater, Akaki, Ethiopia

    NASA Astrophysics Data System (ADS)

    Fitamo, Daniel; Itana, Fisseha; Olsson, Mats

    2007-02-01

    . Generally, a considerable proportion of the total levels of many of the heavy metals resided in non residual fractions. The enhanced lability is generally expected to follow the order: Cd > Co > Pb > Cu > Ni > Se > V and Pb > Cd > Co > Cu > Ni > Zn in Vertisol and Fluvisol, respectively. For the similar wastewater application, the soil variables influence the status and the distribution of the associated heavy metals among the different soil fractions in the study soils. Among heavy metals that presented relatively elevated levels and with potential mobility, Co, Cu, Ni (either soil), V (Vertisol), Pb, and Zn (Fluvisol) could pose health threat through their introduction into the food chain in the wastewater irrigated soils.

  16. Biological control of trace metal and organometal benthic fluxes in a eutrophic lagoon (Thau Lagoon, Mediterranean Sea, France)

    NASA Astrophysics Data System (ADS)

    Point, D.; Monperrus, M.; Tessier, E.; Amouroux, D.; Chauvaud, L.; Thouzeau, G.; Jean, F.; Amice, E.; Grall, J.; Leynaert, A.; Clavier, J.; Donard, O. F. X.

    2007-04-01

    In situ benthic chamber experiments were conducted in the Thau Lagoon that allowed the simultaneous determination of the benthic exchanges of trace metals (Cd, Co, Cu, Mn, Pb and U) and mercury species (iHg and MMHg). Fluxes of organotin compounds (MBT, DBT and TBT) were also investigated for the first time. The benthic incubations were performed during two campaigns at four stations that presented different macrobenthic and macrophytic species distribution and abundance (see [Thouzeau, G., Grall, J., Clavier, J., Chauvaud, L., Jean, F., Leynaert, A., Longpuirt, S., Amice, E., Amouroux, D., 2007. Spatial and temporal variability of benthic biogeochemical fluxes associated with macrophytic and macrofaunal distributions in the Thau lagoon (France). Estuarine, Coastal and Shelf Science 72 (3), 432 446.]). The results indicate that most of the flux intensity as well as the temporal and spatial variability can be explained by the combined influence of microscale and macroscale processes. Microscale changes were identified using Mn flux as a good indicator of the redox conditions at the sediment water interface, and by extension, as an accurate proxy of benthic fluxes for most trace metals and mercury species. We also observed that the redox gradient at the interface is promoted by both microbial and macrobenthic species activity that governs O2 budgets. Macroscale processes have been investigated considering macrobenthic organisms activity (macrofauna and macroalgal cover). The density of such macroorganisms is able to explain most of the spatial and temporal variability of the benthic metal fluxes within a specific site. A tentative estimation of the flux of metals and organometals associated with deposit feeder and suspension feeder activity was found to be in the range of the flux determined within the chambers for most considered elements. Furthermore, a light/dark incubation investigating a dense macroalgal cover present at the sediment surface illustrates the role

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  19. Adsorption of CO on Pd 1/W(110)

    NASA Astrophysics Data System (ADS)

    Zhao, Y. B.; Gomer, R.

    1990-12-01

    The properties of the system CO/Pd 1/W(110) have been investigated. Unlike CO/Cuj/WfllO) there are no particular anomalies in Δ H or surface entropy Ss probably because Pd matches W in size much more closely than does Cu. Δ H decreases with coverage from 21 kcal/mol at low to 12 kcal/mol near saturation coverage. Ss is initially very high, 24 cal mol -1 K -1 and decreases with coverage. It is postulated that the high values at low coverage (and relatively high temperature) correspond to CO being a 2 D gas with additional low energy vibrational degrees of freedom. Isosteric desorption rate measurements yield Edes values lower than desorption enthalpies at θ ⩾ 0.35. The desorption measurements also yield first order frequency factors ν which show a very strong compensation effect: log ν versus Edes is linear over eleven orders of magnitude, i.e. from ν = 10 18s-1 at low coverage, high Edes to ν ≈ 10 7s-1 high coverage, low Edes. The drop in Edes below desorption enthalpies is attributed to steep decreases in sticking coefficient s with increasing surface temperature. At moderate T, s ≈ 1 at low coverage, shows a plateau and then decreases steeply as θ increases. Work function rises nearly linearly with coverage to high values; Δφ = +620 meV at saturation coverage, CO/ Pd = 0.77 or 1.1 × 10 15 molecules cm -2. The He I UPS spectrum for CO on Pd 1/W(110) shows a 5 gs-1 π peak near EF-8 eV, and is very similar to that of CO/Cu 1/W(110). Differences in the binding energy of the O 1s peak for CO/W(110), CO/Cu 1/W(110), and CO/Pd 1/W(110) can be explained almost quantitatively by the differences in the work functions of these surfaces.

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

    PubMed

    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.

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

    SciTech Connect

    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.

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

    PubMed

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

    2016-03-01

    Eighty-four multiparous, nonlactating, pregnant Angus × Hereford cows were ranked by pregnancy type (56 AI and 28 natural service), BW, and BCS and allocated to 21 drylot pens at the end of their second trimester of gestation (d 0). Pens were assigned to receive forage-based diets containing 1) sulfate sources of Cu, Co, Mn, and Zn (INR); 2) an organic complexed source of Cu, Mn, Co, and Zn (AAC; Availa 4; Zinpro Corporation, Eden Prairie, MN); or 3) no supplemental Cu, Co, Mn, and Zn (CON). Diets were offered from d 0 until calving and formulated to meet requirements for energy, protein, macrominerals, Se, I, and vitamins. The INR and AAC diets provided the same daily amount of Cu, Co, Mn, and Zn. Cow BW and BCS were recorded and liver samples were collected on d -10 and 2 wk (d 75) before the calving season. Within 3 h after calving, calf BW was recorded, liver samples were collected, and the expelled placenta was retrieved ( = 47 placentas). Calves were weaned on d 283 of the experiment, preconditioned for 45 d (d 283 to 328), transferred to a growing lot on d 328, and moved to a finishing lot on d 440 where they remained until slaughter. Liver Co, Cu, and Zn concentrations on d 75 were greater ( ≤ 0.05) for INR and AAC cows compared with CON cows, whereas INR cows had reduced ( = 0.04) liver Co but greater ( = 0.03) liver Cu compared with AAC cows. In placental cotyledons, Co concentrations were greater ( ≤ 0.05) in AAC and INR cows compared with CON cows, whereas Cu concentrations were increased ( = 0.05) only in AAC cows compared with CON cows. Calves from INR and AAC cows had greater ( < 0.01) liver Co concentrations at birth compared with calves from CON cows. Liver Cu and Zn concentrations at birth were greater ( ≤ 0.05) in calves from AAC cows compared with cohorts from CON cows. Weaning BW was greater ( ≤ 0.05) in calves from AAC cows compared with cohorts from CON cows, and this difference was maintained until slaughter. In the growing lot

  3. Clues for regulatory processes in fungal uptake and transfer of minerals to the basidiospore.

    PubMed

    Gramss, Gerhard; Voigt, Klaus-Dieter

    2013-07-01

    Several fungal species are notorious for the preferential acquisition of toxicants such as AsCdHgPbU in their wild-grown basidiomes, but it is not known how, or whether at all, mineral uptake is regulated. In this study, basidiomes of Kuehneromyces mutabilis, Pleurotus ostreatus, and Hypholoma fasciculare were grown on Fagus sylvatica logs embedded in sand, uranium-overburden soil, and garden soil (SIO) at a lab scale to raise the accessible mineral resources 30 to >1,000 times over those available in the timber alone. Non-embedded logs and a field culture established on SIO served as controls. Concentrations of 22 minerals were determined by inductively coupled plasma mass spectrometry from microwave-digested samples of timber, soils, whole and dissected mushrooms, and basidiospores. It was the goal to determine whether mineral uptake rates vary simply with their concentration in the substrate or undergo selections which indicate the ability of metal sensing and optimizing/delimiting the quantity of (essential) elements on their passage from a substrate via basidiome to the basidiospores. It is shown that an underrepresented substrate mineral is up-concentrated to a more or less regulated and physiologically compatible mean, whereas a rising external mineral supply leads to uptake blockage by downregulation of the bioconcentration rate in the vicinity of an apparent mycelial saturation point. The resulting concentrations in whole K. mutabilis basidiomes of the essential metals, CaCoCuFeMgMn(Sr)Zn corresponded surprisingly with those in wheat grains which share the main metabolic pathways with fungi and whose metallome is believed to be out-regulated for an optimum and stress-free development. Concentrations of nonessential metals, too, fitted the range of those common crops, whereas KP reached the higher typical level of fungi. Minerals entering the lower stipe of the K. mutabilis basidiome were specifically enriched/diluted on a passage to the gills and once more

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

    PubMed

    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

  5. Effect of diffusive scattering on giant magnetoresistance in magnetic multilayers

    NASA Astrophysics Data System (ADS)

    Stewart, Derek Alan

    2001-07-01

    Dramatic changes in resistance due to external magnetic fields or giant magnetoresistance (GMR) have provided revolutionary advances in disciplines ranging from computer memory to land mine detection. This thesis explores the crucial role of interfaces in producing GMR in systems such as magnetic multilayers and spin valves where magnetic layers (Co or Fe) are separated by simple metal layers of Cu or Cr. A semi-classical Boltzmann transport model is used to model GMR in Co|Cu magnetic multilayers. Parameters required to fit experimental results indicate minority carriers in Co have a very small mean free path and experience enhanced diffusive scattering at layer interfaces. Parameters fitted for magnetic multilayers (>100 layers) are used to calculate the GMR in corresponding spin valve systems. The model provides GMR and resistivity values in good agreement with current experimental results for spin valves. Scattering at a single interface is examined using two techniques to provide a better theoretical basis for treatment of interfaces in semi-classical calculations. An analytical Green's function approach is developed that treats the interface as a sheet of randomly placed point scatterers. This formalism provides closed forms for interface specularity parameters that depend on electron momentum and interface roughness. The specularity parameters for transmission and reflection differ in functional form, a fact neglected in current Boltzmann models. The layered Korringa Kohn Rostoker method (LKKR) is also used to examine transport across free electron and Co|Cu interfaces. The interdiffused region is treated as an alloy layer under the Coherent Potential Approximation (CPA). Specularity parameters found using this technique for free electrons agree well with analytical Green's function results. The LKKR also provides the first energy dependent specularity parameters for a real material interface. The electronic properties of FeCr alloys are examined using the

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Horváth, Adrienn; Bidló, András

    2015-04-01

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

  8. Closed vessel miniaturized microwave assisted chelating extraction for determination of trace metals in plant materials

    NASA Astrophysics Data System (ADS)

    Czarnecki, Sezin; Duering, Rolf-Alexander

    2013-04-01

    In recent years, the use of closed vessel microwave assisted extraction (MAE) for plant samples has shown increasing research interest which will probably substitute conventional procedures in the future due to their general disadvantages including consumption of time and solvents. The objective of this study was to demonstrate an innovative miniaturized closed vessel microwave assisted extraction (µMAE) method under the use of EDTA (µMAE-EDTA) to determine metal contents (Cd, Co, Cu, Mn, Ni, Pb, Zn) in plant samples (Lolio-Cynosuretum) by inductively coupled plasma-optical emission spectrometry (ICP-OES). Validation of the method was done by comparison of the results with another miniaturized closed vessel microwave HNO3 method (µMAE-H) and with two other macro scale MAE procedures (MAE-H and MAE-EDTA) which were applied by using a mixture of nitric acid (HNO3) and hydrogen peroxide (H2O2) (MAE-H) and EDTA (MAE-EDTA), respectively. The already established MAE-H method is taken into consideration as a reference validation MAE method for plant material. A conventional plant extraction (CE) method, based on dry ashing and dissolving of the plant material in HNO3, was used as a confidence comparative method. Certified plant reference materials (CRMs) were used for comparison of recovery rates from different extraction protocols. This allowed the validation of the applicability of the µMAE-EDTA procedure. For 36 real plant samples with triplicates each, µMAE-EDTA showed the same extraction yields as the MAE-H in the determination of Cd, Co, Cu, Mn, Ni, Pb, and Zn contents in plant samples. Analytical parameters in µMAE-EDTA should be further investigated and adapted for other metals of interest. By the reduction and elimination of the use of hazardous chemicals in environmental analysis and thus allowing a better understanding of metal distribution and accumulation process in plants and also the metal transfer from soil to plants and into the food chain, µ

  9. Sedimentology, geochemistry, pollution status and ecological risk assessment of some heavy metals in surficial sediments of an Egyptian lagoon connecting to the Mediterranean Sea.

    PubMed

    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.

  10. Electronic structure and half-metallicity in new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn)

    NASA Astrophysics Data System (ADS)

    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.

  11. Magnetism of coherent Co and Ni thin films on Cu(111) and Au(111) substrates: An ab initio study

    NASA Astrophysics Data System (ADS)

    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.

  12. Long-term assessment of ecological risk from deposition of elemental pollutants in the vicinity of the industrial area of Puchuncaví-Ventanas, central Chile.

    PubMed

    Salmanighabeshi, Soroush; Palomo-Marín, M Rosario; Bernalte, Elena; Rueda-Holgado, Fernando; Miró-Rodríguez, Conrado; Fadic-Ruiz, Ximena; Vidal-Cortez, Víctor; Cereceda-Balic, Francisco; Pinilla-Gil, Eduardo

    2015-09-15

    The present work investigates soil pollution by elemental contaminants and compares ecological risk indexes related to industrial activities for the case study of Puchuncaví-Ventanas: a relevant industrial zone located in central Chile. Selected elements (As, Pb, Cd, Ni, Hg, V, Mn, Zn, Sr, Sb, Cr, Co, Cu, K, and Ba) were analyzed during a long-term period (yearly sampling campaigns during 2007-2011), at 5 sampling stations representing different degrees of impact. PCA and cluster analysis allowed identifying a copper smelter and a coal-fired power plant complex as major pollution sources. Geoaccumulation index (I geo), enrichment factor (EF), contamination factor (Cf), contamination degree (C deg), and integrated pollution index (IPI) are critically discussed for quantitative ecological risk assessment. I geo, EF and Cf indexes are producing comparable environmental information, showing moderate to high pollution risks in the area that demands further monitoring and adoption of prevention and remediation measures. Long term assessment of elemental pollution around an industrial area. New insight on ecological risk indexes for trace element pollution in soils, by critical comparison among them. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. An Electronic Tongue Designed to Detect Ammonium Nitrate in Aqueous Solutions

    PubMed Central

    Campos, Inmaculada; Pascual, Lluis; Soto, Juan; Gil-Sánchez, Luis; Martínez-Máñez, Ramón

    2013-01-01

    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; (NH4)2SO4; 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. PMID:24145916

  15. Synthesis, structure, and magnetic properties of M(N3)2(bpy)

    NASA Astrophysics Data System (ADS)

    Danilović, Dušan; Hamida, Youcef; Lin, C. L.; Yuen, Tan; Li, Kunhao; Li, Jing

    2012-04-01

    Powder crystalline metal-organic frameworks (MOF), M(N3)2(bpy) (where M = Ni, Co, Cu, and bpy = 4,4'-bipyridine), were successfully synthesized by mixing M(II) salts with solutions of 4,4'-bipyridine and NaN3. All three MOFs crystallize in an orthorhombic crystal system with the space group Cmmm (No. 65), which is isostructural to that of 2D-Fe(N3)2(bpy). The M(II) ions are coordinated with four azide ligands (N3) in equatorial plane forming linear magnetic chains. Isothermal magnetization, magnetic susceptibility, and heat capacity measurements were performed. No clear phase transitions were observed. The intra-chain magnetic interaction was found to be ferromagnetic for the Co and Ni compounds, and antiferromagnetic for the Cu compound. The data were fit to theoretical models, and the variation in the exchange interactions was interpreted in terms of the geometric distortions on the octahedral M(II) sites.

  16. Hydrometallurgical separation of aluminium, cobalt, copper and lithium from spent Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Ferreira, Daniel Alvarenga; Prados, Luisa Martins Zimmer; Majuste, Daniel; Mansur, Marcelo Borges

    A hydrometallurgical route based on leaching-crystallization steps for the separation of metals Al, Co, Cu and Li from spent Li-ion batteries was evaluated in this paper. Once dismantled for the removal of both plastic and steel cases, the anode (containing mainly Cu) of such batteries was manually separated from the cathode (which contains Al, Co and Li) for the recovery of Cu. The metal content of both anode and cathode was assessed by X-ray diffraction (XRD), X-ray fluorescence (XRF) and atomic absorption analytical methods. The cathode was firstly leached with NaOH for the selective removal of Al, followed by leaching with H 2SO 4 + H 2O 2 for the dissolution of the remaining Co and Li. The operating variables concentration of NaOH and concentration of H 2O 2 were found significant for the metal dissolution conditions investigated at basic and acid leaching operations, respectively. On the other hand, the variables temperature and concentration of H 2SO 4 showed minor effects at acid leaching step. Reaction schemes were proposed to describe basic and acid leaching operations. The recovery of Co from the acid liquor was carried out by crystallization. This hydrometallurgical route was found to be simple and adequate to separate metals for recycling purposes.

  17. Risk assessment of particle dispersion and trace element contamination from mine-waste dumps.

    PubMed

    Romero, Antonio; González, Isabel; Martín, José María; Vázquez, María Auxiliadora; Ortiz, Pilar

    2015-04-01

    In this study, a model to delimit risk zones influenced by atmospheric particle dispersion from mine-waste dumps is developed to assess their influence on the soil and the population according to the concentration of trace elements in the waste. The model is applied to the Riotinto Mine (in SW Spain), which has a long history of mining and heavy land contamination. The waste materials are separated into three clusters according to the mapping, mineralogy, and geochemical classification using cluster analysis. Two of the clusters are composed of slag, fresh pyrite, and roasted pyrite ashes, which may contain high concentrations of trace elements (e.g., >1 % As or >4 % Pb). The average pollution load index (PLI) calculated for As, Cd, Co, Cu, Pb, Tl, and Zn versus the baseline of the regional soil is 19. The other cluster is primarily composed of sterile rocks and ochreous tailings, and the average PLI is 3. The combination of particle dispersion calculated by a Gaussian model, the PLI, the surface area of each waste and the wind direction is used to develop a risk-assessment model with Geographic Information System GIS software. The zone of high risk can affect the agricultural soil and the population in the study area, particularly if mining activity is restarted in the near future. This model can be applied to spatial planning and environmental protection if the information is complemented with atmospheric particulate matter studies.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    Vamerali, Teofilo; Bandiera, Marianna; Coletto, Lucia; Zanetti, Federica; Dickinson, Nicholas M; Mosca, Giuliano

    2009-03-01

    At a site in Udine, Italy, a 0.7m layer of As, Co, Cu, Pb and Zn contaminated wastes derived from mineral roasting for sulphur extraction had been covered with an unpolluted 0.15m layer of gravelly soil. This study investigates whether woody biomass phytoremediation is a realistic management option. Comparing ploughing and subsoiling (0.35m 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.

  20. Indoor/Outdoor Relationships and Anthropogenic Elemental Signatures in Airborne PM2.5 at a High School: Impacts of Petroleum Refining Emissions on Lanthanoid Enrichment.

    PubMed

    Bozlaker, Ayse; Peccia, Jordan; Chellam, Shankararaman

    2017-05-02

    Outdoor emissions of primary fine particles and their contributions to indoor air quality deterioration were examined by collecting PM2.5 inside and outside a mechanically ventilated high school in the ultraindustrialized ship channel region of Houston, TX over a 2-month period. By characterizing 47 elements including lanthanoids (rare earth elements), using inductively coupled plasma-mass spectrometry, we captured indoor signatures of outdoor episodic emissions arising from nonroutine operations of petroleum refinery fluidized-bed catalytic cracking units. Average indoor-to-outdoor (I/O) abundance ratios for the majority of elements were close to unity providing evidence that indoor metal-bearing PM2.5 had predominantly outdoor origins. Only Co had an I/O abundance ratio >1 but its indoor sources could not be explicitly identified. La and 17 other elements (Na, K, V, Ni, Co, Cu, Zn, Ga, As, Se, Mo, Cd, Sn, Sb, Ba, W, and Pb), including air toxics were enriched relative to the local soil both in indoor and outdoor PM2.5 demonstrating their noncrustal origins. Several lines of evidence including receptor modeling, lanthanoid ratios, and La-Ce-Sm ternary diagrams pointed to petroleum refineries as being largely responsible for enhanced La and total lanthanoid concentrations in the majority of paired indoor and outdoor PM2.5.

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

    PubMed

    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.

  2. Palladium, platinum, rhodium, iridium and ruthenium in chromite- rich rocks from the Samail ophiolite, Oman.

    USGS Publications Warehouse

    Page, N.J.; Pallister, J.S.; Brown, M.A.; Smewing, J.D.; Haffty, J.

    1982-01-01

    30 samples of chromitite and chromite-rich rocks from two stratigraphic sections, 250 km apart, through the basal ultramafic member of the Samail ophiolite were spectrographically analysed for platinum-group elements (PGE) and for Co, Cu, Ni and V. These data are reported as are Cr/(Cr + Al), Mg/(Mg + Fe) and wt.% TiO2 for most samples. The chromitite occurs as pods or lenses in rocks of mantle origin or as discontinuous layers at the base of the overlying cumulus sequence. PGE abundances in both sections are similar, with average contents in chromite-rich rocks: Pd 8 ppb, Pt 14 ppb, Rh 6 ppb, Ir 48 ppb and Ru 135 ppb. The PGE data, combined with major-element and petrographic data on the chromitite, suggest: 1) relatively larger Ir and Ru contents and highest total PGE in the middle part of each section; 2) PGE concentrations and ratios do not correlate with coexisting silicate and chromite abundances or chromite compositions; 3) Pd/PGE, on average, increases upward in each section; 4) Samail PGE concentrations, particularly Rh, Pt and Pd, are lower than the average values for chromite-rich rocks in stratiform intrusions. 2) suggests that PGEs occur in discrete alloy or sulphide phases rather than in the major oxides or silicates, and 4) suggests that chromite-rich rocks from the oceanic upper mantle are depleted in PGE with respect to chondrites. L.C.C.

  3. Accumulation of trace metals in the muscle and liver tissues of five fish species from the Persian Gulf.

    PubMed

    Agah, Homira; Leermakers, Martine; Elskens, Marc; Fatemi, S Mohamad Rez; Baeyens, Willy

    2009-10-01

    In this study, concentrations of 16 elements were quantified in muscles and livers of 141 fishes belonging to five commercially species. It was also our intention to evaluate potential risks to human health associated with seafood consumption. The grunt, flathead, greasy grouper, tiger-tooth croaker and silver pomfret fish species were obtained from Abadan, Deylam, Bushehr-Nirogah, Dayyer port, Lengeh port and Abbas port in Hormozgan, Bushehr and Khozesran provinces at the Iranian waters of the Persian Gulf. The contents of Al, As, Be, Cd, Cr, Co, Cu, Fe, Pb, Mn, Mo, Ni, Sb, Tl, V and Zn in fish muscles and livers were determined by Inductively Coupled Plasma Mass Spectrometry (ICP MS), after digestion in a CEM (Mars 5) microwave oven using nitric acid and hydrogen peroxide. Our results indicated that almost all metals were more accumulated in younger flathead, greasy grouper and tiger-tooth fishes. Contrary to the other fish species, grunt seems to stronger accumulating elements in the older fishes. Strong and positive correlations were observed in three or more of the fish species between V, Al, Fe, Tl, Co and Pb. The results confirmed that fish muscle and liver tissues appeared to be good bio-indicators for identification of coastal areas exposed to metallic contaminants. The results also showed that the element levels in the muscles of all fishes in our study were lower than the maximum allowable concentrations and pose no threat to public health, except for arsenic.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Self-Supported Mesostructured Pt-Based Bimetallic Nanospheres Containing an Intermetallic Phase as Ultrastable Oxygen Reduction Electrocatalysts.

    PubMed

    Kim, Ho Young; Cho, Seonghun; Sa, Young Jin; Hwang, Sun-Mi; Park, Gu-Gon; Shin, Tae Joo; Jeong, Hu Young; Yim, Sung-Dae; Joo, Sang Hoon

    2016-10-01

    Developing highly active and stable cathode catalysts is of pivotal importance for proton exchange membrane fuel cells (PEMFCs). While carbon-supported nanostructured Pt-based catalysts have so far been the most active cathode catalysts, their durability and single-cell performance are yet to be improved. Herein, self-supported mesostructured Pt-based bimetallic (Meso-PtM; M = Ni, Fe, Co, Cu) nanospheres containing an intermetallic phase are reported, which can combine the beneficial effects of transition metals (M), an intermetallic phase, a 3D interconnected framework, and a mesoporous structure. Meso-PtM nanospheres show enhanced oxygen reduction reaction (ORR) activity, compared to Pt black and Pt/C catalysts. Notably, Meso-PtNi containing an intermetallic phase exhibits ultrahigh stability, showing enhanced ORR activity even after 50 000 potential cycles, whereas Pt black and Pt/C undergo dramatic degradation. Importantly, Meso-PtNi with an intermetallic phase also demonstrated superior activity and durability when used in a PEMFC single-cell, with record-high initial mass and specific activities. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Assessment of heavy metals contamination in sediments from three adjacent regions of the Yellow River using metal chemical fractions and multivariate analysis techniques.

    PubMed

    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Flow injection analysis as a tool for enhancing oceanographic nutrient measurements--a review.

    PubMed

    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. Copyright © 2013 Elsevier B.V. All rights reserved.

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

    PubMed

    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.

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

    PubMed

    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

    2014-09-01

    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.

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

    PubMed

    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.

  11. Multivariate Analyses of Heavy Metals in Surface Soil Around an Organized Industrial Area in Eskisehir, Turkey.

    PubMed

    Malkoc, S; Yazici, B

    2017-02-01

    A total of 50 surface industrial area soil in Eskisehir, Turkey were collected and the concentrations of As, Cr, Cd, Co, Cu, Ni, Pb, Zn, Fe and Mg, at 11.34, 95.8, 1.37, 15.28, 33.06, 143.65, 14.34, 78.79 mg/kg, 188.80% and 78.70%, respectively. The EF values for As, Cu, Pb and Zn at a number of sampling sites were found to be the highest among metals. Igeo-index results show that the study area is moderately polluted with respect to As, Cd, Ni. According to guideline values of Turkey Environmental Quality Standard for Soils, there is no problem for Pb, but the Cd values are fairly high. However, Cr, Cu, Ni and Zn values mostly exceed the limits. Cluster analyses suggested that soil the contaminator values are homogenous in those sub classes. The prevention and remediation of the heavy metal soil pollution should focus on these high-risk areas in the future.

  12. Quantification of Heavy Metals in Mining Affected Soil and Their Bioaccumulation in Native Plant Species.

    PubMed

    Nawab, Javed; Khan, Sardar; Shah, Mohammad Tahir; Khan, Kifayatullah; Huang, Qing; Ali, Roshan

    2015-01-01

    Several anthropogenic and natural sources are considered as the primary sources of toxic metals in the environment. The current study investigates the level of heavy metals contamination in the flora associated with serpentine soil along the Mafic and Ultramafic rocks northern-Pakistan. Soil and wild native plant species were collected from chromites mining affected areas and analyzed for heavy metals (Cr, Ni, Fe, Mn, Co, Cu and Zn) using atomic absorption spectrometer (AAS-PEA-700). The heavy metal concentrations were significantly (p < 0.01) higher in mine affected soil as compared to reference soil, however Cr and Ni exceeded maximum allowable limit (250 and 60 mg kg(-1), respectively) set by SEPA for soil. Inter-metal correlations between soil, roots and shoots showed that the sources of contamination of heavy metals were mainly associated with chromites mining. All the plant species accumulated significantly higher concentrations of heavy metals as compared to reference plant. The open dumping of mine wastes can create serious problems (food crops and drinking water contamination with heavy metals) for local community of the study area. The native wild plant species (Nepeta cataria, Impatiens bicolor royle, Tegetis minuta) growing on mining affected sites may be used for soil reclamation contaminated with heavy metals.

  13. Origin of Active Oxygen in a Ternary CuOx /Co3O4–CeO 2 Catalyst for CO Oxidation

    DOE PAGES

    Liu, Zhigang; Wu, Zili; Peng, Xihong; ...

    2014-11-14

    In this paper, we have studied CO oxidation over a ternary CuOx/Co3O4-CeO2 catalyst and employed the techniques of N2 adsorption/desporption, XRD, TPR, TEM, in situ DRIFTS and QMS (Quadrupole mass spectrometer) to explore the origin of active oxygen. DRIFTS-QMS results with labeled 18O2 indicate that the origin of active oxygens in CuOx/Co3O4-CeO2 obeys a model, called as queue mechanism. Namely gas-phase molecular oxygens are dissociated to atomic oxygens and then incorporate in oxygen vacancies located at the interface of Co3O4-CeO2 to form active crystalline oxygens, and these active oxygens diffuse to the CO-Cu+ sites thanks to the oxygen vacancy concentrationmore » magnitude and react with the activated CO to form CO2. This process, obeying a queue rule, provides active oxygens to form CO2 from gas-phase O2 via oxygen vacancies and crystalline oxygen at the interface of Co3O4-CeO2.« less

  14. Identifying the origin of atmospheric inputs of trace elements in the Prades Mountains (Catalonia) with bryophytes, lichens, and soil monitoring.

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Exposure of the endangered golden monkey (Rhinopithecus roxellana) to heavy metals: a comparison of wild and captive animals.

    PubMed

    Liu, Qiang; Chen, Yi-Ping; Maltby, Lorraine; Ma, Qing-Yi

    2015-05-01

    Golden monkeys are endemic to China and of high conservation concern. Conservation strategies include captive breeding, but the success of captive breeding programs may be being compromised by environmental pollution. Heavy metal exposure of wild and captive golden monkeys living in the Qinling Mountains was assessed by measuring fecal metal concentrations (As, Cd, Cr, Co, Cu, Mn, Hg, Ni, Pb, and Zn). Captive monkeys were exposed to higher concentrations of As, Hg, Pb, and Cr than monkeys living in the wild, while high background levels of Mn led to high exposure of wild monkeys. Seasonal variations in metal exposures were detected for both wild and captive monkeys; possible reasons being seasonal changes in either diet (wild monkeys) or metal content of food (captive monkeys). Coal combustion, waste incineration, and traffic-related activities were identified as possible sources of heavy metals exposure for captive animals. Efforts to conserve this endangered primate are potentially compromised by metal pollutants derived from increasing anthropogenic activities. Providing captive animals with uncontaminated food and relocating captive breeding centers away from sources of pollution will reduce pollutant exposure; but ultimately, there is a need to improve environmental quality by controlling pollutants at source.

  17. Evaluation of diffusive gradients in thin film (DGT) samplers for measuring contaminants in the Antarctic marine environment.

    PubMed

    Larner, Bronwyn L; Seen, Andrew J; Snape, Ian

    2006-10-01

    This work has been the first application of DGT samplers for measuring metals in water and sediment porewater in the Antarctic environment, and whilst DGT water sampling was restricted to quantification of Cd, Fe and Ni, preconcentration using Empore chelating disks provided results for an additional nine elements (Sn, Pb, Al, Cr, Mn, Co, Cu, Zn, As). Although higher concentrations were measured for some metals (Cd, Ni, Pb) using the Empore technique, most likely due to particulate-bound or colloidal species becoming entrapped in the Empore chelating disks, heavy metal concentrations in the impacted Brown Bay were found to be comparable with the non-impacted O'Brien Bay. Sediment porewater sampling using DGT also indicated little difference between Brown Bay and O'Brien Bay for many metals (Cd, Al, Cr, Co, Ni, Cu), however, greater amounts of Pb, Mn, Fe and As were accumulated in DGT probes deployed in Brown Bay compared with O'Brien Bay, and a higher accumulation of Sn was observed in Brown Bay inner than any of the other three sites sampled. Comparison of DGT derived porewater concentrations with actual porewater concentrations showed limited resupply of Cd, Pb, Al, Cr, Mn, Co, Ni, Cu, Zn and As from the solid phase to porewater, with these metals appearing to be strongly bound to the sediment, however, resupply of Fe and Sn was apparent. Based upon our observations here, we suggest that Sn, and to a lesser extent Pb, are critical contaminants.

  18. Antiferromagnet-induced perpendicular magnetic anisotropy in ferromagnetic/antiferromagnetic/ferromagnetic trilayers

    NASA Astrophysics Data System (ADS)

    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.

  19. Trace elements and electrolytes in human resting mixed saliva after exercise

    PubMed Central

    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

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

    PubMed Central

    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

  1. 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.

    PubMed

    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.

  2. Metal concentrations in sediments from tourist beaches of Miri City, Sarawak, Malaysia (Borneo Island).

    PubMed

    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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Control of Adsorbate/Substrate Charge Transfer Through Coadsorption in the CO/S/Cu(111) System

    NASA Astrophysics Data System (ADS)

    Verma, R.; Sun, Z.-J.; Culver, J. P.; Hochstrasser, R. M.; Yodh, A. G.

    1996-03-01

    The nature of the charge transfer between an adsorbate and a metal surface determines the various energy transfer processes which are important for thermal and photoinduced surface reactions. Coadsorbate sytems provide an environment enabling the modification of these processes. We present FTIR data of an annealed OCS/Cu(111) surface. We find through isotope and TPD studies that this sytem can be described as CO adsorbed on a sulphur modified Cu(111) surface. A spectrum of this modified surface reveals an infrared absorption frequency of the CO stretch (2140cm -1) to be much closer to the gas phase value (2143cm -1) as opposed to what is seen for CO on a clean Cu(111) surface (2070cm -1). This suggests that the partial filling of the antibonding CO 2π^* is diminished relative to CO/Cu(111). We will discuss the relevance of this work to ultrafast energy transfer measurements. Supported by the Materials Reasearch Laboratory Grant DMR 91-20668. ^Also supported by NSF through PYI program and by the Alfred P. Sloan Foundation.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. First-principles investigation of transient spin transfer torque in magnetic multilayer systems

    NASA Astrophysics Data System (ADS)

    Yu, Zhizhou; Zhang, Lei; Wang, Jian

    2017-08-01

    By employing the nonequilibrium Green's function (NEGF) method, the transient current and the transient behavior of the spin transfer torque (STT) of the magnetic layered system are investigated within the framework of density functional theory (DFT). To reduce the huge computational cost of the transient calculation, especially when the dense mesh of k sampling is present for layered systems, the complex absorbing potential (CAP) and the Padé spectrum decomposition are used so that the energy integrals in calculating transient current and STT can be performed analytically using residue theorem, which dramatically reduces the computational complexity of the first-principles calculation of transient behavior. As an application of the NEGF-DFT-CAP formalism, the transient current and current-induced STT of the Co/Cu/Co trilayer system are studied under an upward bias pulse for different angles of magnetization direction between two leads. The transient current shows a damped oscillatory behavior with the oscillation frequency proportional to the applied bias, leading to a relaxation time of hundreds of femtoseconds. The time-dependent STTs show roughly the same profile for systems with different rotating angles. The oscillation behavior is also observed as the transient STT approaches the steady state value. Such oscillations can be attributed to the interface resonant states.

  6. STM studies of spin-spin interactions between Mn acceptors in p-type GaAs

    NASA Astrophysics Data System (ADS)

    Lee, Donghun; Daughton, David R.; Gupta, Jay A.

    2008-03-01

    We use a custom STM operating in a cryogenic, ultrahigh vacuum environment to study spin-spin interactions in semiconductors at the single-impurity level. By applying a voltage pulse with the STM tip, single magnetic impurities (e.g. Mn) can be substituted for Ga atoms in the first layer of the GaAs(110) surface. It was previously found that pairs of Mn acceptors exhibit an exchange splitting which depends on their separation and crystal orientation [2]. We are developing a capability for spin-polarized STM to better study long range magnetic ordering between pairs and larger clusters of Mn acceptors. To characterize the magnetic orientation of our STM tips, we have prepared samples such as Co/Cu(111) which exhibits out-of-plane magnetization, and Cr(001), which is an antiferromagnet with in-plane magnetic contrast between alternating terraces. http://www.physics.ohio-state.edu/˜jgupta [2] D. Kitchen et al., Nature 442, 436-439 (2006)

  7. Effect of added dietary cobalt on metabolism and distribution of radioactive selenium and stable minerals

    SciTech Connect

    Van Ryssen, J.B.J.; Miller, W.J.; Gentry, R.P.; Neathery, M.W.

    1987-03-01

    Retention of /sup 75/Se following a single oral dose and stable Co, Cu, Zn, and Mg were determined in tissues of calves fed a diet containing 0, 10, or 40 ppm supplemental Co for 21 d. Concentrations of /sup 75/Se in tissue were numerically higher with 10 ppm Co than with the other two diets, but the effect was significant only in small intestine tissues of calves fed 40 ppm Co. Dietary Co did not affect fecal /sup 75/Se. Average total fecal /sup 75/Se excretion was 53, 48, and 51% of the dose over 6 d in calves fed 0, 10, and 40 ppm added Co. Concentrations of Co in tissues increased with increased supplementation. Dietary Co did not significantly affect growth, feed intake, tissue Zn, tissue Cu, blood hemoglobin, packed cell volume, plasma alkaline phosphatase, or plasma glutamic oxaloacetic transaminase. Magnesium in heart and skeletal muscle was increased in calves fed 40 ppm Co. Although high amounts of added dietary Co had some influence on metabolism of Se, the magnitude and extent of the effects appeared to be too small to be of practical concern.

  8. Assessment of essential and nonessential dietary exposure to trace elements from homegrown foodstuffs in a polluted area in Makedonska Kamenica and the Kočani region (FYRM).

    PubMed

    Vrhovnik, Petra; Dolenec, Matej; Serafimovski, Todor; Tasev, Goran; Arrebola, Juan P

    2016-07-15

    The main purpose of the present study is to assess human dietary exposure to essential and non-essential trace elements via consumption of selected homegrown foodstuffs. Twelve essential and non-essential trace elements (Cd, Co, Cu, Cr, Hg, Mo, Ni, Pb, Sb, Se, Zn and As) were detected in various homegrown foodstuffs. Detailed questionnaires were also applied among a sample of the local population to collect information on sociodemographic characteristics. The results of the present study clearly indicate that the majority of the trace elements are at highly elevated levels in the studied foodstuffs, in comparison to international recommendations. The maximum measured levels of ETE and NETE are as follows [μgkg(-1)]: Cd 873, Co 1370, Cu 21700, Cr 59633, Hg 26, Mo 6460, Ni14.5, Pb 11100, Sb 181, Se 0.30, Zn 102 and As 693. Additionally, age, body mass index and gender were significantly associated with levels of dietary exposure. Further research is warranted on the potential health implication of this exposure. The study merges the accumulation of ETE and NETE in home-grown foodstuffs and reflects considerably high health risks for inhabitants. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Leaching of major and minor elements during the transport and storage of coal ash obtained in power plant.

    PubMed

    Krgović, Rada; Trifković, Jelena; Milojković-Opsenica, Dušanka; Manojlović, Dragan; Mutić, Jelena

    2014-01-01

    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.

  10. Contamination by trace elements at e-waste recycling sites in Bangalore, India.

    PubMed

    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.

  11. Evaluation of Reactive Mixtures for Passive Treatment of Mine Drainage from a Waste Rock Storage Area

    NASA Astrophysics Data System (ADS)

    Jeen, S. W.; Mattson, B.

    2014-12-01

    Laboratory column tests for a passive treatment system for mine drainage from a waste rock storage area was conducted to evaluate suitable reactive mixture, system configuration, flow rate, and residence time. Five columns containing straw, chicken manure, mushroom compost, and limestone, either in layered or mixed, were set up and operated for a total of 74 days to simulate the treatment system. The key variables determined from the tests include pH and redox adjustment of the treatment system, treatment efficiency for acidity and metals, sulfate removal rates, and precipitation of secondary minerals as sinks for metals. The results showed that all of the five columns removed metals of concern (i.e., Al, Cd, Co, Cu, Fe, Ni, Zn) with residence time of 15 hours and greater. The organic materials used in the test provided sufficient sulfate reduction that is available for metal removal in the mine drainage. The sulfate removal rates ranged between 200 and 600 mg/L/day. Reaction mechanisms responsible for the removal of metals may include sulfate reduction and subsequent sulfide precipitation, precipitation of secondary carbonates and hydroxides, co-precipitation, and sorption on organic materials and secondary precipitates. The results from the columns tests provide a basis for design of a pilot-scale field passive treatment system, such as permeable reactive barrier (PRB) or reducing and alkalinity producing system (RAPS).

  12. Potential Health Benefits and Metabolomics of Camel Milk by GC-MS and ICP-MS.

    PubMed

    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.

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

    PubMed

    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.

  14. Re-evaluation and extension of the scope of elements in US Geological Survey Standard Reference Water Samples

    USGS Publications Warehouse

    Peart, D.B.; Antweiler, R.C.; Taylor, H.E.; Roth, D.A.; Brinton, T.I.

    1998-01-01

    More than 100 US Geological Survey (USGS) Standard Reference Water Samples (SRWSs) were analyzed for numerous trace constituents, including Al, As, B, Ba, Be, Bi, Br, Cd, Cr, Co, Cu, I, Fe, Pb, Li, Mn, Mo, Ni, Rb, Sb, Se, Sr, Te, Tl, U, V, Zn and major elements (Ca, Mg, Na, SiO2, SO4, Cl) by inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry. In addition, 15 USGS SRWSs and National Institute of Standards and Technology (NIST) standard reference material (SRM) 1641b were analyzed for mercury using cold vapor atomic fluorescence spectrometry. Also USGS SRWS Hg-7 was analyzed using isotope dilution-inductively coupled plasma mass spectrometry. The results were compared with the reported certified values of the following standard reference materials: NIST SRM 1643a, 1643b, 1643c and 1643d and National Research Council of Canada Riverine Water Reference Materials for Trace Metals SLRS-1, SLRS-2 and SLRS-3. New concentration values for trace and major elements in the SRWSs, traceable to the certified standards, are reported. Additional concentration values are reported for elements that were neither previously published for the SRWSs nor traceable to the certified reference materials. Robust statistical procedures were used that were insensitive to outliers. These data can be used for quality assurance/quality control purposes in analytical laboratories.

  15. Calcium phenylphosphonate as a host for 4-aminobenzoic acid-Synthesis, characterization, and cation adsorption from ethanol solution

    SciTech Connect

    Lazarin, Angelica M.; Ganzerli, Thiago A.; Sernaglia, Rosana L.; Andreotti, Elza I.S.; Airoldi, Claudio

    2009-11-15

    Crystalline lamellar calcium phenylphosphonate retained 4-aminobenzoic acid inside its cavity without leaching. The intense infrared bands in the 1160-695 cm{sup -1} interval confirmed the presence of the phosphonate groups attached to the inorganic layer, with sharp and intense peaks in X-ray diffraction patterns, which gave basal distances of 1532 and 1751 pm for the original and the intercalated compounds, respectively. The thermogravimetric curves of both layered compounds showed the release of water molecules and the organic moiety in distinct stages, to yield a final Ca(PO{sub 3}){sub 2} residue. Solid-state {sup 31}P nuclear magnetic resonance spectra presented only one peak for the phenylphosphonate groups attached to the main inorganic polymeric structure near 12.4 ppm. The adsorption isotherms from ethanol gave the maximum adsorption capacities of 1.68 and 0.50 mmol g{sup -1} for copper and cobalt, respectively, whose average stability constants followed Co > Cu; the number of ligands was determined as four for both cations.

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

    NASA Astrophysics Data System (ADS)

    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 <2000 μm revealed the presence of "hot spots" of pollution caused by heavy metal contaminants in some Aveiro 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).

  17. Characterization, distribution, and risk assessment of heavy metals in agricultural soil and products around mining and smelting areas of Hezhang, China.

    PubMed

    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.

  18. Trace elements in a Pliocene-Pleistocene lignite profile from the Afsin-Elbistan field, eastern Turkey

    SciTech Connect

    Karayigit, A.I.; Gayer, R.A.

    2000-01-01

    The authors present the results of proximate and ultimate analyses, mineralogical determination, and trace element analysis of a lignite profile from the Afsin-Elbistan field (eastern Turkey). The lignite, which developed during the Pliocene-Pleistocene transition under freshwater lacustrine conditions, contains white gastropod (Planorbidae) shells composed of calcite and a little aragonite. Other identifiable mineral constituents, analyzed by X-ray powder diffraction, include quartz, pyrite, clay minerals, and rare feldspares. Petrographical studies demonstrate the immature nature of these lignites and very low degree of compaction during diagenesis. The mean concentrations of trace elements in the lignite, determined by inductively coupled plasma mass spectrometry (ICP-MS), show relative enrichment in Mo (avg. 20 ppm), W (avg. 15 ppm) and U (avg. 25 ppm) when compared to the global range for most coals, while the others (Ti, p, Sc, Be, Mn, Co, Cu, Zn, Ga, As, Rb, Sr, Zr, Nb, Cs, Ba, Y, Ta, Tl, Pb, Bi, Th, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu) fall within their global ranges. Many of the trace elements show a good correlation with the ash yield, implying an inorganic affinity. However, Mo and Sr show a negative correlation with the ash yield and are thought to be organically associated. A lack of correlation of U with either the ash yield or the coal sulfur content, together with its relative enrichment, suggests secondary mobility of this element.

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

    PubMed Central

    Krgović, Rada; Trifković, Jelena; Milojković-Opsenica, Dušanka; Manojlović, Dragan; Mutić, Jelena

    2014-01-01

    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. PMID:25101314

  20. Elemental analysis of granite by instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF).

    PubMed

    El-Taher, A

    2012-01-01

    The instrumental neutron activation analysis technique (INAA) was used for qualitative and quantitative analysis of granite samples collected from four locations in the Aswan area in South Egypt. The samples were prepared together with their standards and simultaneously irradiated in a neutron flux of 7×10(11)n/cm(2)s in the TRIGA Mainz research reactor. Gamma-ray spectra from an hyper-pure germanium detector were analyzed. The present study provides the basic data of elemental concentrations of granite rocks. The following elements have been determined Na, Mg, K, Fe, Mn, Sc, Cr, Ti, Co, Zn, Ga, Rb, Zr, Nb, Sn, Ba, Cs, La, Ce, Nd, Sm, Eu, Yb, Lu, Hf, Ta, Th and U. The X-ray fluorescence (XRF) was used for comparison and to detect elements, which can be detected only by XRF such as F, S, Cl, Co, Cu, Mo, Ni, Pb, Se and V. The data presented here are our contribution to understanding the elemental composition of the granite rocks. Because there are no existing databases for the elemental analysis of granite, our results are a start to establishing a database for the Egyptian granite. It is hoped that the data presented here will be useful to those dealing with geochemistry, granite chemistry and related fields.

  1. Factors to consider for trace element deposition biomonitoring surveys with lichen transplants.

    PubMed

    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.

  2. The bark of the branches of holm oak (Quercus ilex L.) for a retrospective study of trace elements in the atmosphere.

    PubMed

    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.

  3. Modeling precipitation and sorption of elements during mixing of river water and porewater in the Coeur d'Alene River basin

    USGS Publications Warehouse

    Balistrieri, L.S.; Box, S.E.; Tonkin, J.W.

    2003-01-01

    Reddish brown flocs form along the edge of the Coeur d'Alene River when porewater drains into river water during the annual lowering of water level in the basin. The precipitates are efficient scavengers of dissolved elements and have characteristics that may make metals associated with them bioavailable. This work characterizes the geochemistry of the porewater and models the formation and composition of the flocs. Porewater is slightly acidic, has suboxic to anoxic characteristics, tends to have higher alkalinity, and contains elevated concentrations of many constituents relative to river water. Laboratory mixing experiments involving porewater and river water were done to produce the precipitates. Thermodynamic predictions using PHREEQC indicate that predicted amounts of ferrihydrite and gibbsite agree with removal of Fe and Al. Predictions of element removal by adsorption onto ferrihydrite are consistent with observed removal using a combination of surface complexation constants for the generalized two-layer model (As and Se), alternative surface constants derived from experiments at high sorbate-to-sorbent ratios (Cd, Co, Cu, Ni, Pb, and Zn), and adjusted surface constants to fit experimental data (Cr, Mo, and Sb). This new set of surface complexation constants needs further testing in other contaminated systems.

  4. Synthesis of Multimetal-Graphene Composite by Mechanical Milling

    NASA Astrophysics Data System (ADS)

    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.

  5. Simulation of the potential effects of CO2 leakage from carbon capture and storage activities on the mobilization and speciation of metals.

    PubMed

    de Orte, Manoela Romanó; Sarmiento, Aguasanta M; DelValls, T Ángel; Riba, Inmaculada

    2014-09-15

    One of the main risks associated with carbon capture and storage (CCS) activities is the leakage of the stored CO2, which can result in several effects on the ecosystem. Laboratory-scale experiments were performed to provide data on the possible effects of CO2 leakage from CCS on the mobility of metals previously trapped in sediments. Metal-contaminated sediments were collected and submitted to acidification by means of CO2 injection using different pH treatments. The test lasted 10 days, and samples were collected at the beginning and at the end of the experiment for metal analysis. The results revealed increases in the mobility of metals such as Co, Cu, Fe, Pb and Zn due to pH decreases. Geochemical modeling demonstrated that acidification influenced the speciation of the metals, increasing the concentrations of their free forms. These data suggest the possible sediment contamination consequences of accidental CO2 leakage during CCS activities. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Abundance and distribution of boron in the Hauzenberg (Bavaria) granite complex

    SciTech Connect

    Sauerer, A.; Troll, G. )

    1990-01-01

    Hercynian S-type granites from the Hauzenberg igneous complex show a range of boron concentration from 1 to 12 ppm. The whole-rock boron data are not significantly correlated with concentrations of other trace elements (Zr, Rb, Ba, Sr, Ni, V, Co, Cu, Zn, F); neither is boron correlated with the major elements (except with sodium) or with the differentiation index (DI). The boron budget in the rock-forming minerals (plagioclase, alkali feldspar, quartz, biotite, muscovite) of the tourmaline-free granites reveals that the highest concentrations of boron occur in muscovite, whereas the greatest amount of boron is incorporated in plagioclase (57-69%) due to its high modal amount. Boron in plagioclase increases with the extent of of sericitization (obtained by X-ray diffractometry). Muscovite in a pegmatite contains more than 50% of the total boron. The areal distribution of boron within the complex is neither uniform nor random; an increase of boron concentrations from granodioritic to granitic rocks is indicated, whereas the late differentiates are depleted in boron.

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

    PubMed Central

    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

  8. Enhanced O2 selectivity versus N2 by partial metal substitution in Cu-BTC

    SciTech Connect

    Sava Gallis, Dorina F.; Parkes, Marie V.; Greathouse, Jeffery A.; Zhang, Xiaoyi; Nenoff, Tina M.

    2015-03-05

    Here we describe the homogeneous substitution of Mn, Fe and Co at various levels into a prototypical metal-organic framework (MOF), namely Cu-BTC (HKUST-1), and the effect of that substitution on preferential gas sorption. Using a combination of density functional theory (DFT) calculations, postsynthetic metal substitutions, materials characterization, and gas sorption testing, we demonstrate that the identity of the metal ion has a quantifiable effect on their oxygen and nitrogen sorption properties at cryogenic temperatures. An excellent correlation is found between O2/N2 selectivities determined experimentally at 77 K and the difference in O2 and N2 binding energies calculated from DFT modeling data: Mn > Fe > Co > Cu. Room temperature gas sorption studies were also performed and correlated with metal substitution. The Fe-exchanged sample shows a significantly higher nitrogen isosteric heat of adsorption at temperatures close to ambient conditions (273 K - 298 K) as compared to all other metals studied, indicative of favorable interactions between N2 and coordinatively unsaturated Fe metal centers. Furthermore, differences in gas adsorption results at cryogenic and room temperatures are evident; they are explained by comparing experimental results with DFT binding energies (0 K) and room temperature Grand Canonical Monte Carlo simulations.

  9. Determination of the performance of vermicomposting process applied to sewage sludge by monitoring of the compost quality and immune responses in three earthworm species: Eisenia fetida, Eisenia andrei and Dendrobaena veneta.

    PubMed

    Suleiman, Hanine; Rorat, Agnieszka; Grobelak, Anna; Grosser, Anna; Milczarek, Marcin; Płytycz, Barbara; Kacprzak, Małgorzata; Vandenbulcke, Franck

    2017-10-01

    The aim of this study was to assess the effectiveness of vermicomposting process applied on three different sewage sludge (precomposted with grass clippings, sawdust and municipal solid wastes) using three different earthworm species. Selected immune parameters, namely biomarkers of stress and metal body burdens, have been used to biomonitor the vermicomposting process and to assess the impact of contaminants on earthworm's physiology. Biotic and abiotic parameters were also used in order to monitor the process and the quality of the final product. Dendrobaena veneta exhibited much lower resistance in all experimental conditions, as the bodyweight and the total number of circulating immune cells decreased in the most contaminated conditions. All earthworm species accumulated heavy metals as follows Cd>Co>Cu>Zn>Ni>Pb>Cr: Eisenia sp. worms exhibited the highest ability to accumulate several heavy metals. Vermicompost obtained after 45days was acceptable according to agronomic parameters and to compost quality norms in France and Poland. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Development of 3D functionally graded models by laser-assisted coaxial powder injection

    NASA Astrophysics Data System (ADS)

    Yakovlev, Artem; Bertrand, Ph.; Smurov, Igor Y.

    2004-04-01

    Relatively new method of producing 3D objects with Functionally Graded Material (FGM) structure is realized by coaxial powder injection with variable composition into the zone of laser beam action. The desired 3-dimensional material distribution is realized by repetitive deposition process. Theoretical analysis and experimental results show essential role of radiation mode and powder granularity as optimization parameters. Applied laser sources are continuous wave Nd:YAG(HAAS 2006D, 2kW), pulse-periodic Nd:YAG(HAAS HL304P, avg. power 300 W), quazi-cw CO2 (Rofin-Sinar, 300 W). Among applied materials are nanostructured WC/Co, CuSn, Stainless steel 316L, 430L, Co-base alloy, nanostructured FeCu, etc. The originality of obtained results is that different gradient types are produced "in situ" and combined within one sample: smooth, sharp or multilayered gradients. The number of samples is produced and examined with metallographical and SEM analysis. The minimal spatial gradient resolution (transition zone between two different materials) is starting from 10 microns and can be varied in a wide range; the surface roughness depends from powder granularity, best value of Ra is about 5 μm, microhardness of differet zones of samples is varied from 120 to 450 HV. The achieved geometry spatial resolution is 200 μm.

  12. Metal and metalloid concentrations in the giant squid Architeuthis dux from Iberian waters.

    PubMed

    Bustamante, P; González, A F; Rocha, F; Miramand, P; Guerra, A

    2008-08-01

    This study investigated 14 trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V and Zn) in the tissues of the giant squid Architeuthis dux from the Mediterranean and Atlantic Spanish waters. As for other families of cephalopods, the digestive gland and the branchial hearts of Architeuthis showed the highest concentrations of Ag, Cd, Co, Cu, Fe, Ni, Se, V and Zn, highlighting their major role in the bioaccumulation and detoxification processes. With the exception of Hg, the muscles showed relatively low trace element concentrations. Nevertheless, this tissue contained the main proportion of the total As, Cr, Hg, Mn, Ni, and Zn body burden because muscles represent the main proportion of the squid mass. These findings suggest that the metal metabolism is overall the same as other cephalopod families from neritic waters. In females, Zn concentrations increased in the digestive gland with the squid's weight likely reflecting physiological changes during sexual maturation. Comparing the trace element concentrations in the tissues of Architeuthis, higher Ag, Cu, Hg and Zn concentrations in the squid from the Mediterranean reflected different exposure conditions. In comparison to other meso-pelagic squids from the Bay of Biscay, Cd concentrations recorded in the digestive gland suggest that Architeuthis might feed on more contaminated prey or that it displays a longer life span that other cephalopods.

  13. Association Analysis of SSR Markers with Phenology, Grain, and Stover-Yield Related Traits in Pearl Millet (Pennisetum glaucum (L.) R. Br.)

    PubMed Central

    Senapathy, Senthilvel; Chandra, Subhash; Muthiah, Arunachalam; Dhanapal, Arun Prabhu; Hash, Charles Thomas

    2014-01-01

    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. PMID:24526909

  14. Determination of trace level impurities in uranium compounds by ICP-AES after organic extraction.

    PubMed

    Marin, S; Cornejo, S; Jara, C; Duran, N

    1996-06-01

    The determination was studied of Al, B, Be, Cd, Ca, Co, Cu, Mg, Mn, Mo, Pb, Si, Sn, V, Cr, Ni, and Fe as trace level impurities in uranium compounds by ICP-AES after extraction of uranium with three different mixtures of di-(2-ethyl-hexyl) phosphate (D2EHP) and tri-(2-ethyl-hexyl)-phosphate (T2EHP) in solvents like toluene, carbon tetrachloride, hexane and cyclohexane. The study was carried out in presence of different concentrations of HCl and HNO(3). A single extraction with D2EHP in cyclohexane using nitric acid as matrix was sufficient to reduce the U(3)O(8) concentration from 100 g/l to 100 microg/ml. The ICP-AES instrumentation applied, allowed the determination of metal concentrations ten-times lower than those usually found in nuclear grade U(3)O(8). To check the efficiency of the extraction and the accuracy of the proposed method, Certified Reference Materials were used in the dissolution and extraction steps. The method described can be used for the determination of trace metals in nuclear grade U(3)O(8).

  15. [Comparative analysis of trace elements in five marine-derived shell TCM using multivariate statistical analysis].

    PubMed

    Zhang, Shuai; Chen, Zhen; Fu, Yu-qiang; Gong, Hui-li; Guan, Hua-shi; Liu, Hong-bing

    2015-11-01

    A comparable study were carried out by determination of trace elements on five marine-derived shell traditional Chinese medicine (TCM) (Ostreae Concha, Haliotidis Concha, Margaritifera Concha, Meretricis Concha, and Arcae Concha), which were recorded in the Chinese Pharmacopoeia (2010 version). Seven trace elements in 51 batches of this type of shell TCM were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), combined with principal component analysis (PCA) methods. The content of element Se, which exhibited significant differences among different drugs, could be used as a key element to distinguish this type of drugs. Meanwhile, the contents of elements Co, Cu, Mo, and Ba in Haliotidis Concha, Co and As in Margaritifera Concha, Mo and As in Meretricis Concha, Mo, As, and Ba in Arcae Concha, and Zn in Meretricis Concha were relatively stable. In the PCA plot, Arcae Concha and Meretricis Concha could be efficiently distinguished from Ostreae Concha together with Haliotidis Concha, and Margaritifera Concha. The results also showed a correlation with their medicinal function. In conclusion, trace elements in marine-derived shell TCM could not be neglected for their quality control.

  16. Free-time and fixed end-point optimal control theory in dissipative media: application to entanglement generation and maintenance.

    PubMed

    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.

  17. [Heavy Metals Pollution in Topsoil from Dagang Industry Area and Its Ecological Risk Assessment].

    PubMed

    Zhang, Qian; Chen, Zong-juan; Peng, Chang-sheng; Li, Fa-sheng; Gu, Qing-bao

    2015-11-01

    Based on previous studies and field investigation of Dagang industry area in Tianjin, a total of 128 topsoil samples were collected, and contents of 10 heavy metals (As, Cd, Cr, Co, Cu, Pb, Ni, V, Zn and Hg) were determined. The geoaccumulation index and geostatistics were applied to examine the degree of contamination and spatial distribution of heavy metals in topsoil. The assessment on ecological risk of heavy metals was carried out using Hakanson's method, and the main resources of the heavy metals were analyzed as well. It was found that As, Cd and Co had the highest proportions exceeding Tianjin background value, which were 100%, 97.66% and 96.88%, respectively; the heavy-metal content increased to some extent comparing with that in 2004, and the pollutions of As and Cd were the worst, and other metals were at moderate pollution level or below. The ecological risks of heavy metals were different in topsoil with different land use types, the farmland soil in the southwest as well as soils adjacent to the industrial land were at relatively high potential ecological risk level, and the integrated ecological risk index reached up to 1 437.37. Analysis of correlation and principal component showed that traffic and transportation as well as agricultural activities might be the main resources of heavy metals in the area, besides, the industrial activities in the region might also affect the accumulation of heavy metals.

  18. Minor and trace element concentrations in adjacent kamacite and taenite in the Krymka chondrite

    NASA Astrophysics Data System (ADS)

    Meftah, N.; Mostefaoui, S.; Jambon, A.; Guedda, E. H.; Pont, S.

    2016-04-01

    We report in situ NanoSIMS siderophile minor and trace element abundances in individual Fe-Ni metal grains in the unequilibrated chondrite Krymka (LL3.2). Associated kamacite and taenite of 10 metal grains in four chondrules and one matrix metal were analyzed for elemental concentrations of Fe, Ni, Co, Cu, Rh, Ir, and Pt. The results show large elemental variations among the metal grains. However, complementary and correlative variations exist between adjacent kamacite-taenite. This is consistent with the unequilibrated character of the chondrite and corroborates an attainment of chemical equilibrium between the metal phases. The calculated equilibrium temperature is 446 ± 9 °C. This is concordant with the range given by Kimura et al. (2008) for the Krymka postaccretion thermal metamorphism. Based on Ni diffusivity in taenite, a slow cooling rate is estimated of the Krymka parent body that does not exceed ~1K Myr-1, which is consistent with cooling rates inferred by other workers for unequilibrated ordinary chondrites. Elemental ionic radii might have played a role in controlling elemental partitioning between kamacite and taenite. The bulk compositions of the Krymka metal grains have nonsolar (mostly subsolar) element/Ni ratios suggesting the Fe-Ni grains could have formed from distinct precursors of nonsolar compositions or had their compositions modified subsequent to chondrule formation events.

  19. Physical resuspension and vertical mixing of sediments on a high energy continental margin (Sydney, Australia).

    PubMed

    Matthai, C; Birch, G F; Jenkinson, A; Heijnis, H

    2001-01-01

    Four sediment cores from the continental margin adjacent to Sydney were analyzed for 210Pb, 137Cs, trace metals (Ag, Cd, Co, Cu, Mn, Ni, Pb, Zn), iron, dry bulk density, mud and moisture content. The concentrations of trace metals in the total sediment are low at all sites, although slightly elevated concentrations of Ag, Cu, Pb and Zn are present in the fine fraction of sediment (< 62.5 microns) near a major ocean outfall. Concentrations of trace metals in the fine fraction of sediment are similar in the upper 10-15 cm, indicating strong vertical mixing of the sediments, whereas an upward coarsening grain size in the upper 1-3 cm of sediment supports physical resuspension during storms. Sediment accumulation rates on the middle shelf adjacent to Sydney were estimated from downcore profiles of 210Pb and 137Cs and range between 0.2 and 0.4 cm yr-1. Although the mass fluxes of Cu, Pb and Zn within a distance of 2 km from the outfall (up to 36.1, 30.8 and 86.2 micrograms cm-2 yr-1, respectively) are greater than 20 km north of the outfall (< 23.5 micrograms cm-2 yr-1), the low concentrations of trace metals in sediments near the outfall support an efficient dispersal of anthropogenic contaminants on this continental margin.

  20. Trace metals and organochlorines in sediments near a major ocean outfall on a high energy continental margin (Sydney, Australia).

    PubMed

    Matthai, C; Birch, G F

    2000-12-01

    Sewage effluent from a large ocean outfall south of Sydney, southeastern Australia, is efficiently dispersed on this high energy continental margin. An enrichment of Ag, Cu, Pb and Zn is only detectable in the fine fraction (<62.5 microm) of sediment. Ag, Co, Cu, Ni, Pb and Zn in the bulk sample correlate strongly with the mud content of surficial sediment, making an identification of the anthropogenic trace metal source difficult using total sediment analyses. The concentrations of HCB and DDE in the total sediment are also slightly elevated near the outfall. In the vicinity of the outfall, the estimated sewage component in the fine fraction of sediment, using Ag, Cu and Zn in a conservative, two-endmember physical mixing model, is <5% and is <0.25% of the total sediment. A greater anthropogenic Pb component in the fine fraction (mean: 24.8%) of surficial sediment compared to Ag, Cu and Zn may suggest a source other than sewage to Sydney continental margin sediments.