Luminescence of delafossite-type CuAlO2 fibers with Eu substitution for Al cations

PubMed Central

Liu, Yin; Gong, Yuxuan; Mellott, Nathan P.; Wang, Bu; Ye, Haitao; Wu, Yiquan

2016-01-01

Abstract CuAlO2 has been examined as a potential luminescent material by substituting Eu for Al cations in the delafossite structure. CuAlO2:Eu3+ nanofibers have been prepared via electrospinning for the ease of mitigating synthesis requirements and for future optoelectronics and emerging applications. Single-phase CuAlO2 fibers could be obtained at a temperature of 1100 °C in air. The Eu was successfully doped in the delafossite structure and two strong emission bands at ~405 and 610 nm were observed in the photoluminescence spectra. These bands are due to the intrinsic near-band-edge transition of CuAlO2 and the f-f transition of the Eu3+ activator, respectively. Further electrical characterization indicated that these fibers exhibit semiconducting behavior and the introduction of Eu could act as band-edge modifiers, thus changing the thermal activation energies. In light of this study, CuAlO2:Eu3+ fibers with both strong photoluminescence and p-type conductivity could be produced by tailoring the rare earth doping concentrations. PMID:27877870

Luminescence of delafossite-type CuAlO2 fibers with Eu substitution for Al cations

NASA Astrophysics Data System (ADS)

Liu, Yin; Gong, Yuxuan; Mellott, Nathan P.; Wang, Bu; Ye, Haitao; Wu, Yiquan

2016-01-01

CuAlO2 has been examined as a potential luminescent material by substituting Eu for Al cations in the delafossite structure. CuAlO2:Eu3+ nanofibers have been prepared via electrospinning for the ease of mitigating synthesis requirements and for future optoelectronics and emerging applications. Single-phase CuAlO2 fibers could be obtained at a temperature of 1100 °C in air. The Eu was successfully doped in the delafossite structure and two strong emission bands at 405 and 610 nm were observed in the photoluminescence spectra. These bands are due to the intrinsic near-band-edge transition of CuAlO2 and the f-f transition of the Eu3+ activator, respectively. Further electrical characterization indicated that these fibers exhibit semiconducting behavior and the introduction of Eu could act as band-edge modifiers, thus changing the thermal activation energies. In light of this study, CuAlO2:Eu3+ fibers with both strong photoluminescence and p-type conductivity could be produced by tailoring the rare earth doping concentrations.

Luminescence of delafossite-type CuAlO2 fibers with Eu substitution for Al cations.

PubMed

Liu, Yin; Gong, Yuxuan; Mellott, Nathan P; Wang, Bu; Ye, Haitao; Wu, Yiquan

2016-01-01

CuAlO 2 has been examined as a potential luminescent material by substituting Eu for Al cations in the delafossite structure. CuAlO 2 :Eu 3+ nanofibers have been prepared via electrospinning for the ease of mitigating synthesis requirements and for future optoelectronics and emerging applications. Single-phase CuAlO 2 fibers could be obtained at a temperature of 1100 °C in air. The Eu was successfully doped in the delafossite structure and two strong emission bands at ~405 and 610 nm were observed in the photoluminescence spectra. These bands are due to the intrinsic near-band-edge transition of CuAlO 2 and the f-f transition of the Eu 3+ activator, respectively. Further electrical characterization indicated that these fibers exhibit semiconducting behavior and the introduction of Eu could act as band-edge modifiers, thus changing the thermal activation energies. In light of this study, CuAlO 2 :Eu 3+ fibers with both strong photoluminescence and p-type conductivity could be produced by tailoring the rare earth doping concentrations.

Photocatalytic properties and selective antimicrobial activity of TiO2(Eu)/CuO nanocomposite

NASA Astrophysics Data System (ADS)

Michal, Robert; Dworniczek, Ewa; Caplovicova, Maria; Monfort, Olivier; Lianos, Panagiotis; Caplovic, Lubomir; Plesch, Gustav

2016-05-01

TiO2(Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO2(Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO2(Eu). In investigated TiO2(Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

Novel europium (III)-gatifloxacin complex structure with dual functionality for pH sensing and metal recognition in aqueous environment

NASA Astrophysics Data System (ADS)

Chen, Muhua; Zheng, Yuhui; Gao, Jinwei; Wang, Qianming

2016-10-01

A new type of Eu(III)-gatifloxacin complex with characteristic red luminescence has been prepared. Due to the presence of ionization effect linked to the organic chromophore, the molecular fluorescent sensor demonstrated variable pH-sensitive absorption and emission curves. The red emission derived from europium ions was strong during pH range 8-10. Between pH = 7 and 4, the europium emission remained relatively stable and fluorescence signals of gatifloxacin has been improved substantially. Under acidic conditions (pH = 1 to 3), the dramatic changes in the emission colors (from red, yellow to green) were clearly observed. Moreover, the excitation wavelength can be extended into the visible light range (Ex = 411 nm) by using the concentration effect experiment. Importantly, it gave turn-off emissions in the presence of Cu2+ or Fe3+ and the detection limits were determined to be 6.5 μM for Cu2+ and 6.2 μM for Fe3+ respectively.

Diffuse-flow hydrothermal field in an oceanic fracture zone setting, Northeast Pacific: Deposit composition

USGS Publications Warehouse

Hein, J.R.; Koski, R.A.; Embley, R.W.; Reid, J.; Chang, S.-W.

1999-01-01

This is the first reported occurrence of an active hydrothermal field in an oceanic fracture zone setting. The hydrothermal field occurs in a pull-apart basin within the Blanco Fracture Zone (BFZ), which has four distinct mineral deposit types: (1) barite mounds and chimneys, (2) barite stockwork breccia, (3) silica-barite beds, and (4) silica, barite, and Fe-Mn oxyhydroxide in sediments. All deposit types contain minor amounts of sulfides. In barite stockwork, silica-barite beds, and mineralized sediment, Ba, Ph, Ag, S, Au, Zn, Cu, Hg, TI, As, Mo, Sb, U, Cd, and Cu are enriched relative to unmineralized rocks and sediments of the BFZ. Fe and Mn are not enriched in the barite stockwork or silica-barite beds, but along with P, Co, and Mg are enriched in the mineralized sediments. Silver contents in deposits of the hydrothermal field range up to 86 ppm, gold to 0.7 ppm, zinc to 3.2%, copper to 0.8%, and barium to 22%. Mineralization occurred by diffuse, low to intermediate temperature (mostly <250??C) discharge of hydrothermal fluids through pillow lavas and ponds of mixed volcaniclastic and biosiliceous sediments. Bacterial mats were mineralized by silica, barite, and minor Fe hydroxides, or less commonly, by Mn oxyhydroxides. Pervasive mineralization of bacterial mats resulted in formation of silica-barite beds. Silica precipitated from hydrothermal fluids by conductive cooling and mixing with seawater. Sulfate, U, and rare earth elements (REEs) in barite were derived from seawater, whereas the REE content of hydrothermal silica deposits and mineralized sediments is associated with the aluminosilicate detrital fraction. Fe-, Zn-, Cu-, Pb-, and Hg-sulfide minerals, Ba in barite, and Eu in all mineralized deposits were derived from hydrothermal fluids. Manganese oxides and associated elements (Co, Sb, Mo, W, Cl, and Cu) and Fe oxides and associated elements (Be, B, P, and Mo) precipitated as the result of mixing of hydrothermal fluids with seawater. ?? 2001 Canadian Institute of Mining, Metallurgy and Petroleum. All rights reserved.

A Eu(III) doped metal-organic framework conjugated with fluorescein-labeled single-stranded DNA for detection of Cu(II) and sulfide.

PubMed

Weng, Han; Yan, Bing

2017-10-02

In this paper, Bio-MOF-1 is prepared as reported and then Eu 3+ is introduced into it via cation exchange method. A FAM-labeled ssDNA is chosen to fabricate with the obtained Eu 3+ @Bio-MOF-1. A luminescent hybrid material is assembled, which can exhibit the fluorescence of Eu 3+ and FAM simultaneously by adjusting the ratio of FAM-ssDNA and Eu 3+ @Bio-MOF-1. The sample is then used for the detecting of metal ions, results shows which has good selectively for Cu 2+ (LOD = 0.14 μM, 0-250 μM). The introduction of Cu 2+ can quench the fluorescence of FAM while the luminescent intensity of Eu 3+ enhancing. After the detection of Cu 2+ , the Cu 2+ involved hybrid system can then be further employed for the detection of S 2- (LOD = 1.3 μM, 0-50 μM). Low concentration of S 2- can make the luminescent intensity of Eu 3+ decrease gradually while high concentration of S 2- can further recover the luminescent of FAM, which is quenched by Cu 2+ . Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetism of the 35 K superconductor CsEuFe4As4

NASA Astrophysics Data System (ADS)

Albedah, Mohammed A.; Nejadsattari, Farshad; Stadnik, Zbigniew M.; Liu, Yi; Cao, Guang-Han

2018-04-01

The results of ab initio hyperfine-interaction parameters calculations, and of x-ray diffraction and 57Fe and 151Eu Mössbauer spectroscopy study of the new 35 K superconductor CsEuFe4As4 are reported. The superconductor crystallizes in the tetragonal space group P4/mmm with the lattice parameters a = 3.8956(1) Å and c = 13.6628(5) Å. It is demonstrated unequivocally that there is no magnetic order of the Fe magnetic moments down to 2.1 K and that the ferromagnetic order is associated with the Eu magnetic moments. The Curie temperature TC = 15.97(8) K determined from the temperature dependence of the hyperfine magnetic field at 151Eu nuclei is shown to be compatible with the temperature dependence of the transferred hyperfine magnetic field at 57Fe nuclei that is induced by the ferromagnetically ordered Eu sublattice. The Eu magnetic moments are shown to be perpendicular to the crystallographic c-axis. The temperature dependence of the principal component of the electric field gradient tensor, both at Fe and Eu sites, is well described by a T 3/2 power-law relation. Good agreement between the calculated and measured hyperfine-interaction parameters is observed. The Debye temperature of CsEuFe4As4 is found to be 295(3) K.

Mössbauer spectroscopy measurements on the 35.5 K superconductor Rb1 -δEuFe4As4

NASA Astrophysics Data System (ADS)

Albedah, Mohammed A.; Nejadsattari, Farshad; Stadnik, Zbigniew M.; Liu, Yi; Cao, Guang-Han

2018-04-01

The results of x-ray diffraction and 57Fe and 151Eu Mössbauer spectroscopy measurements, supplemented with ab initio hyperfine-interaction parameter calculations, on the new 35.5 K superconductor Rb1 -δEuFe4As4 are presented. The superconductor crystallizes in the tetragonal space group P 4 /m m m with the lattice parameters a =3.8849 (1 ) Å and c =13.3370 (3 ) Å. It is shown that there is no magnetic order of the Fe magnetic moments down to 2.1 K and that the ferromagnetic order is associated solely with the Eu magnetic moments. The Curie temperature TC=16.54 (8 ) K is determined from the temperature dependence of both the hyperfine magnetic field at 151Eu nuclei and the transferred hyperfine magnetic field at 57Fe nuclei that is induced by the ferromagnetically ordered Eu sublattice. The Eu magnetic moments are demonstrated to be perpendicular to the crystallographic c axis. The temperature dependence of the principal component of the electric field gradient tensor, at both Fe and Eu sites, is well described by a T3 /2 power-law relation. Good agreement between the calculated and measured hyperfine-interaction parameters is observed. The Debye temperature of Rb1 -δEuFe4As4 is found to be 391(8) K.

Magnetocaloric behavior in ternary europium indides EuT 5In: Probing the design capability of first-principles-based methods on the multifaceted magnetic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bigun, Inna; Steinberg, Simon; Smetana, Volodymyr

The most favorable structures and the types of magnetic ordering predicted from first-principles-based methods in a family of closely related transition-metal-rich indides EuT 5In (T = Cu, Ag, Au) are gauged against relevant experiments. The EuT5In compounds adopt a different structure for each different coinage metal—EuCu 5In ( hR42; Rmore » $$\\overline{3}$$m, a = 5.0933(7), c = 30.557(6) Å), EuAg 5In ( oP28; Pnma, a = 9.121(2), b = 5.645(1), c = 11.437(3) Å), and EuAu 5In ( tI14; I4/ mmm, a = 7.1740(3), c = 5.4425(3) Å)—and crystallize with the Sr 5Al 9, CeCu 6, and YbMo 2Al 4 structure types, respectively. EuCu 5In and EuAg 5In order antiferromagnetically at T N = 12 and 6 K, respectively, whereas EuAu 5In is ferromagnetic below T C = 13 K. EuCu 5In exhibits complex magnetism: after the initial drop at T N, the magnetization rises again below 8 K, and a weak metamagnetic-like transition occurs at 2 K in μ 0H = 1.8 T. The electronic heat capacity of EuCu 5In, γ = ~400 mJ/(mol K 2), points to strong electronic correlations. Spin-polarized densities of states suggest that the magnetic interactions in the three materials studied are supported via mixing 4 f and 5 d states of Eu. As a result, a chemical bonding analysis based on the Crystal Orbital Hamilton populations reveals the tendency to maximize overall bonding as a driving force to adopt a particular type of crystal structure.« less

Magnetocaloric behavior in ternary europium indides EuT 5In: Probing the design capability of first-principles-based methods on the multifaceted magnetic materials

DOE PAGES

Bigun, Inna; Steinberg, Simon; Smetana, Volodymyr; ...

2017-01-27

The most favorable structures and the types of magnetic ordering predicted from first-principles-based methods in a family of closely related transition-metal-rich indides EuT 5In (T = Cu, Ag, Au) are gauged against relevant experiments. The EuT5In compounds adopt a different structure for each different coinage metal—EuCu 5In ( hR42; Rmore » $$\\overline{3}$$m, a = 5.0933(7), c = 30.557(6) Å), EuAg 5In ( oP28; Pnma, a = 9.121(2), b = 5.645(1), c = 11.437(3) Å), and EuAu 5In ( tI14; I4/ mmm, a = 7.1740(3), c = 5.4425(3) Å)—and crystallize with the Sr 5Al 9, CeCu 6, and YbMo 2Al 4 structure types, respectively. EuCu 5In and EuAg 5In order antiferromagnetically at T N = 12 and 6 K, respectively, whereas EuAu 5In is ferromagnetic below T C = 13 K. EuCu 5In exhibits complex magnetism: after the initial drop at T N, the magnetization rises again below 8 K, and a weak metamagnetic-like transition occurs at 2 K in μ 0H = 1.8 T. The electronic heat capacity of EuCu 5In, γ = ~400 mJ/(mol K 2), points to strong electronic correlations. Spin-polarized densities of states suggest that the magnetic interactions in the three materials studied are supported via mixing 4 f and 5 d states of Eu. As a result, a chemical bonding analysis based on the Crystal Orbital Hamilton populations reveals the tendency to maximize overall bonding as a driving force to adopt a particular type of crystal structure.« less

Mineralogical and geochemical features of the coarse saprolite developed on orthogneiss in the SW of Yaoundé, South Cameroon

NASA Astrophysics Data System (ADS)

Ndjigui, P.-D.; Badinane, M. F. B.; Nyeck, B.; Nandjip, H. P. K.; Bilong, P.

2013-03-01

A petrological investigation was performed in the coarse saprolite on orthogneiss in Yaoundé (South Cameroon) using combined whole rock geochemical (XRF, ICP-MS) and mineralogical (XRD, SEM) techniques. The orthogneiss has high contents in SiO2 (61.56 wt.%), Ba (916 ppm) and REE (209 ppm), moderate content in Al2O3 (14.34 wt.%) and negative Eu anomaly (Eu/Eu* = 0.68). The weathering leads to the formation of three main constituents in the coarse saprolite: (i) the loose materials (∼85 vol.%) are basically clayey silty with relic structure. They are composed of kaolinite, quartz and goethite. The loose materials have high contents in SiO2 (56-64.83 wt.%) and Al2O3 (21.48-23.96 wt.%), and moderate contents in V (163-236 ppm), Ba (95-340 ppm) and Zr (160-313 ppm). The REE content is low (∼49-169 ppm) relative to the parent rock with LREE-enrichment (LREE/HREE ∼ 7-17). Positive Ce anomaly (Ce/Ce* ∼ 3.35) is observed in the white veins and slight positive Eu anomalies (Eu/Eu* ∼ 1.2-1.4) are noted in all loose samples. The (La/Yb)N ratios (∼0.8-1.5) indicate high REE-fractionation. The mass balance calculation reveals the depletion of several elements except Al, Ti, Sc, Y, Th, Sb and Hf; (ii) the iron duricrust (∼10 vol.%) is located at the bottom and the top of the horizon. The mineral assemblage is dominated by hematite and goethite. The upper iron duricrust has high contents in Fe2O3 (45.60 wt.%) and Cr (1641 ppm), moderate contents in V (459 ppm) and Zn (143 ppm), and low REE content (47 ppm) with low LREE/HREE ratio (4.28). The upper iron duricrust is more enriched in Fe2O3 (53.26 wt.%) than the lower one. Vanadium, Cr and Zr have high contents relative to other trace elements. The REE content is low (39 ppm) as well as the LREE/HREE ratio (2.94). The iron duricrust has negative Ce anomalies (Ce/Ce* ∼ 0.66-0.69) and very low (La/Yb)N ratios (0.1-0.3). Several elements reported in the iron duricrust are highly leached except Fe, Cr, Zn, Sc, V, Pb, Zr, Cu and Th; and (iii) the Mn-rich materials (<5 vol.%) are made up of birnessite, cryptomelane, and low quantities of quartz, kaolinite and goethite. The SEM investigation reveals that Ba and Pb are linked in Mn-bearing phases and Ce-oxides appear as fine-grained intergrowth between Mn-bearing phases. The Mn-bearing phases are enriched in MnO (33.86 wt.%), BaO (4.30 wt.%), Co (1716 ppm), Pb (1315 ppm) and Ce (5202 ppm). Positive Ce and Eu anomalies are observed (Ce/Ce* ∼ 15.60 and Eu/Eu* ∼ 2). The mass balance calculations indicate the strong accumulation of Mn, Ni, Co, Zn, Sc, Cu, Ba, Pb, Y, Ga, Zr and REE. The Mn-bearing phases might be derived from the accumulation of silicate residues and Mn within the parent rock. The transition from the parent rock to the coarse saprolite is marked by high leaching of several elements.

Transcriptomic and physiological characterization of the fefe mutant of melon (Cucumis melo) reveals new aspects of iron–copper crosstalk

PubMed Central

Waters, Brian M.; McInturf, Samuel A.; Amundsen, Keenan

2014-01-01

Summary Iron (Fe) and copper (Cu) homeostasis are tightly linked across biology. In previous work, Fe deficiency interacted with Cu regulated genes and stimulated Cu accumulation. The C940-fe (fefe) Fe uptake mutant of melon (Cucumis melo) was characterized, and the fefe mutant was used to test whether Cu deficiency could stimulate Fe uptake. Wild type and fefe mutant transcriptomes were determined by RNA-seq under Fe and Cu deficiency. FeFe regulated genes included core Fe uptake, metal homeostasis, and transcription factor genes. Numerous genes were regulated by both Fe and Cu. The fefe mutant was rescued by high Fe or by Cu deficiency, which stimulated ferric-chelate reductase activity, FRO2 expression, and Fe accumulation. Accumulation of Fe in Cu deficient plants was independent of the normal Fe uptake system. One of the four FRO genes in the melon and cucumber (Cucumis sativus) genomes was Fe regulated, and one was Cu regulated. Simultaneous Fe and Cu deficiency synergistically upregulated Fe uptake gene expression. Overlap in Fe and Cu deficiency transcriptomes highlights the importance of Fe– Cu crosstalk in metal homeostasis. The fefe gene is not orthologous to FIT, thus identification of this gene will provide clues to help understand regulation of Fe uptake in plants. PMID:24975482

Rapid and highly efficient preconcentration of Eu(III) by core-shell structured Fe3O4@humic acid magnetic nanoparticles.

PubMed

Yang, Shitong; Zong, Pengfei; Ren, Xuemei; Wang, Qi; Wang, Xiangke

2012-12-01

In this study, humic acid-coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)@HA MNPs) were synthesized using a chemical coprecipitation method and characterized in detail. The XRD analysis results showed that HA coating did not change the phase of Fe(3)O(4) cores. The TEM image suggested that Fe(3)O(4)@HA MNPs had nearly uniform size without the observation of aggregation. The Fe(3)O(4)@HA MNPs were stable in solution and could be easily separated from aqueous solution using a magnetic separation method. A batch technique was adopted to investigate the removal efficiency of Fe(3)O(4)@HA MNPs toward Eu(III) under various environmental conditions. The kinetic process of Eu(III) sorption on Fe(3)O(4)@HA MNPs reached equilibrium within <30 min. The fast sorption kinetics and high sorption amount were attributed to the plentiful surface sites provided by the surface-coated HA macromolecules. The Fe(3)O(4)@HA MNPs was able to remove ~99% of Eu(III) in aqueous solution at pH 8.5. Except for SO(4)(2-) anions, the coexisting electrolyte ions had no significant competition effects on the removal of Eu(III) by Fe(3)O(4)@HA MNPs. The obvious sorption-desorption hysteresis suggested that the removal of Eu(III) was dominated by inner-sphere surface complexation. The sorption isotherm agreed well with the Langmuir model, having a maximum sorption capacity of 6.95 × 10(-5) mol g(-1). The leaching test showed that the Eu(III)-loaded Fe(3)O(4)@HA colloids were capable to maintain high thermodynamic stability for long aging times. The findings herein suggested that Fe(3)O(4)@HA MNPs could be potentially used as a highly effective material for the enrichment and preconcentration of radionuclide Eu(III) or other trivalent lanthanides/actinides in geological repositories or in nuclear waste management.

Treatment of reverse osmosis (RO) concentrate by the combined Fe/Cu/air and Fenton process (1stFe/Cu/air-Fenton-2ndFe/Cu/air).

PubMed

Ren, Yi; Yuan, Yue; Lai, Bo; Zhou, Yuexi; Wang, Juling

2016-01-25

To decompose or transform the toxic and refractory reverse osmosis (RO) concentrate and improve the biodegradability, 1stFe/Cu/air-Fenton-2ndFe/Cu/air were developed to treat RO concentrate obtained from an amino acid production plant in northern China. First, their operating conditions were optimized thoroughly. Furthermore, 5 control experiments were setup to confirm the superiority of 1stFe/Cu/air-Fenton-2ndFe/Cu/air and synergistic reaction between Fe/Cu/air and Fenton. The results suggest that the developed method could obtain high COD removal (65.1%) and BOD5/COD ratio (0.26) due to the synergistic reaction between Fe/Cu/air and Fenton. Under the optimal conditions, the influent and effluent of 1stFe/Cu/air-Fenton-2ndFe/Cu/air and 5 control experiments were analyzed by using UV, FTIR, EEM and LC, which confirm the superiority of 1stFe/Cu/air-Fenton-2ndFe/Cu/air. Therefore, the developed method in this study is a promising process for treatment of RO concentrate. Copyright © 2015 Elsevier B.V. All rights reserved.

[Effect of Eu(Pr) substitution at Ba sites on microstructure and superconductivity in EuBa2Cu3O7-delta ceramics].

PubMed

Peng, Zhen-sheng; Wang, Zhi-he

2004-04-01

Ceramics of Eu1+xBa2-xCu3O7-delta with x = 0.0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 and EuBa2-xPrxCu3O7-delta with x=0.0, 0.05, 0.1, 0.2, 0.3, 0.4 have been synthesized and investigated by X-ray diffraction, resistivity, and Raman spectroscopy. The results show that the transition of crystal structure from orthorhombic to tetragonal occurs and the criticaltemperature decreases withthe increase in doping concentration x. The Raman spectra show that the frequency of the Cu(1)-O(4) stretching mode andthe Cu(2)-(2, 3) out-of-phase mode shifts to higher wave number with increasing doping concentration x.

Structural, XPS and magnetic studies of pulsed laser deposited Fe doped Eu{sub 2}O{sub 3} thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Sandeep; Prakash, Ram, E-mail: rpgiuc@gmail.com; Choudhary, R.J.

2015-10-15

Highlights: • Growth of Fe doped Eu{sub 2}O{sub 3} thin films by PLD. • XRD and Raman’s spectroscopy used for structure confirmation. • The electronic states of Eu and Fe are confirmed by XPS. • Magnetic properties reveals room temperature magnetic ordering in deposited film. - Abstract: Fe (4 at.%) doped europium (III) oxide thin film was deposited on silicon (1 0 0) substrate by pulsed laser deposition technique. Structural, spectral and magnetic properties were studied by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and magnetization measurements. XRD and Raman spectroscopy reveal that the grown film is singlemore » phased and belongs to the cubic structure of Eu{sub 2}O{sub 3}. XPS study of the Eu{sub 1.92}Fe{sub 0.08}O{sub 3} film shows that Fe exists in Fe{sup 3+} ionic state in the film. The film exhibits magnetic ordering at room temperature.« less

Optimal copper supply is required for normal plant iron deficiency responses

PubMed Central

Waters, Brian M; Armbrust, Laura C

2013-01-01

Iron (Fe) and copper (Cu) homeostasis are tightly linked across biology. Understanding crosstalk between Fe and Cu nutrition could lead to strategies for improved growth on soils with low or excess metals, with implications for agriculture and phytoremediation. Here, we show that Cu and Fe nutrition interact to increase or decrease Fe and/or Cu accumulation in leaves and Fe uptake processes. Leaf Cu concentration increased under low Fe supply, while high Cu lowered leaf Fe concentration. Ferric reductase activity, an indicator of Fe demand, was inhibited at insufficient or high Cu supply. Surprisingly, plants grown without Fe were more susceptible to Cu toxicity. PMID:24084753

Optimal copper supply is required for normal plant iron deficiency responses.

PubMed

Waters, Brian M; Armbrust, Laura C

2013-01-01

Iron (Fe) and copper (Cu) homeostasis are tightly linked across biology. Understanding crosstalk between Fe and Cu nutrition could lead to strategies for improved growth on soils with low or excess metals, with implications for agriculture and phytoremediation. Here, we show that Cu and Fe nutrition interact to increase or decrease Fe and/or Cu accumulation in leaves and Fe uptake processes. Leaf Cu concentration increased under low Fe supply, while high Cu lowered leaf Fe concentration. Ferric reductase activity, an indicator of Fe demand, was inhibited at insufficient or high Cu supply. Surprisingly, plants grown without Fe were more susceptible to Cu toxicity.

The pH-dependent leaching behavior of slags from various stages of a copper smelting process: Environmental implications.

PubMed

Jarošíková, Alice; Ettler, Vojtěch; Mihaljevič, Martin; Kříbek, Bohdan; Mapani, Ben

2017-02-01

The leaching behaviors of primary copper (Cu) slags originating from Ausmelt, reverbatory, and converter furnaces operating under a single technological process were compared to a residual slag tailing obtained by slag re-processing via flotation and metal recovery. The EN 12457-2 leaching test, used for assessment of the hazardous properties, was followed by the CEN/TS 14997 pH-static leaching test (pH range 3-12). Both leaching experiments were coupled with a mineralogical investigation of the primary and secondary phases as well as geochemical modeling. Metals (Cd, Cu, Pb, Zn) exhibit the highest leaching at low pH. Under acidic conditions (pH 3-6), Ausmelt slag and slag tailing exhibited higher metal leaching compared to other slag types. Very low leaching of metals (far below EU limits for non-hazardous waste) was observed at natural pH (7.9-9.0) for all the studied slag samples. In contrast, relatively high leaching of As was observed over the entire pH range, especially for Ausmelt slag (exceeding the EU limit for hazardous waste by 1.7×). However, geochemical modeling and scanning electron microscopy indicated that formation of stable Ca-Cu-Pb arsenates and the binding of As to newly formed Fe (oxyhydr)oxides play an important role in efficient As immobilization at the slag-water interface. In contrast, no controls were predicted for Sb, whose leaching was almost pH-independent. Nevertheless Sb leached concentrations at natural pH were below EU limit for hazardous waste. Re-processing of primary Cu slags for metal recovery, and subsequent co-disposal of the resulting slag tailing with dolomite-rich mine tailing and local laterite is suitable for stabilizing the remaining contaminants (except Sb) and limiting their leaching into the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

RbEu (Fe1-xNix) 4As4 : From a ferromagnetic superconductor to a superconducting ferromagnet

NASA Astrophysics Data System (ADS)

Liu, Yi; Liu, Ya-Bin; Yu, Ya-Long; Tao, Qian; Feng, Chun-Mu; Cao, Guang-Han

2017-12-01

The intrinsically hole-doped RbEuFe4As4 exhibits bulk superconductivity at Tsc=36.5 K and ferromagnetic ordering in the Eu sublattice at Tm=15 K. Here we present a hole-compensation study by introducing extra itinerant electrons via a Ni substitution in the ferromagnetic superconductor RbEuFe4As4 with Tsc>Tm . With the Ni doping, Tsc decreases rapidly, and the Eu-spin ferromagnetism and its Tm remain unchanged. Consequently, the system RbEu (Fe1-xNix) 4As4 transforms into a superconducting ferromagnet with Tm>Tsc for 0.07 ≤x ≤0.08 . The occurrence of superconducting ferromagnets is attributed to the decoupling between Eu2 + spins and superconducting Cooper pairs. The superconducting and magnetic phase diagram is established, which additionally includes a recovered yet suppressed spin-density-wave state.

Systems Ln-Fe-O ( Ln=Eu, Gd): thermodynamic properties of ternary oxides using solid-state electrochemical cells

NASA Astrophysics Data System (ADS)

Parida, S. C.; Rakshit, S. K.; Dash, S.; Singh, Ziley; Prasad, R.; Venugopal, V.

2003-05-01

The standard molar Gibbs energies of formation of LnFeO 3(s) and Ln3Fe 5O 12(s) where Ln=Eu and Gd have been determined using solid-state electrochemical technique employing different solid electrolytes. The reversible e.m.f.s of the following solid-state electrochemical cells have been measured in the temperature range from 1050 to 1255 K. Cell (I): (-)Pt / { LnFeO 3(s)+ Ln2O 3(s)+Fe(s)} // YDT/CSZ // {Fe(s)+Fe 0.95O(s)} / Pt(+); Cell (II): (-)Pt/{Fe(s)+Fe 0.95O(s)}//CSZ//{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}/Pt(+); Cell (III): (-)Pt/{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}//YSZ//{Ni(s)+NiO(s)}/Pt(+); and Cell(IV):(-)Pt/{Fe(s)+Fe 0.95O(s)}//YDT/CSZ//{ LnFeO 3(s)+ Ln3Fe 5O 12(s)+Fe 3O 4(s)}/Pt(+). The oxygen chemical potentials corresponding to the three-phase equilibria involving the ternary oxides have been computed from the e.m.f. data. The standard Gibbs energies of formation of solid EuFeO 3, Eu 3Fe 5O 12, GdFeO 3 and Gd 3Fe 5O 12 calculated by the least-squares regression analysis of the data obtained in the present study are given by Δ fG°m(EuFeO 3, s) /kJ mol -1 (± 3.2)=-1265.5+0.2687( T/K) (1050 ⩽ T/K ⩽ 1570), Δ fG°m(Eu 3Fe 5O 12, s)/kJ mol -1 (± 3.5)=-4626.2+1.0474( T/K) (1050 ⩽ T/K ⩽ 1255), Δ fG°m(GdFeO 3, s) /kJ mol -1 (± 3.2)=-1342.5+0.2539( T/K) (1050 ⩽ T/K ⩽ 1570), and Δ fG°m(Gd 3Fe 5O 12, s)/kJ·mol -1 (± 3.5)=-4856.0+1.0021( T/K) (1050 ⩽ T/K ⩽ 1255). The uncertainty estimates for Δ fG°m include the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagrams for the systems Eu-Fe-O and Gd-Fe-O and chemical potential diagrams for the system Gd-Fe-O were computed at 1250 K.

Levels of Organochlorine Pesticides and Heavy Metals in Surface Waters of Konya Closed Basin, Turkey

PubMed Central

Aydin, Mehmet Emin; Ozcan, Senar; Beduk, Fatma; Tor, Ali

2013-01-01

The concentrations of organochlorine pesticides (OCPs), including α-, β-, γ-, and δ-hexachlorocyclohexane (HCH), heptachlor, heptachlor epoxide, dieldrin, aldrin, endrin, endrin aldehyde, endrin ketone, endosulfan I, endosulfan II, endosulfan sulfate, p,p′-DDE, p,p′-DDD, p,p′-DDT, methoxychlor, chlordane I, chlordane II, and heavy metals, such as As, Cr, Cu, Fe, Mn, and Ni in surface water samples from the Konya closed basin were determined to evaluate the level of contamination. Among all HCH isomers, β-HCH is the main isomer with a concentration range of 0.015–0.065 μg/L. DDE, DDD, and DDT were almost determined in all samples, in which DDE isomer had the highest concentration ranged from not detected to 0.037 μg/L. In all studied OCPs, aldrin showed the highest concentration at 0.220 μg/L. The concentrations of heavy metals in water samples were observed with order: Mn < Cu < Ni < As < Cr < Fe. In some samples, As, Fe, and Cr concentrations exceeded the drinking water quality recommended by EU, US EPA, WHO, and Turkish Regulation, while Cu, Ni, and Mn concentrations are below the guideline values. The levels of both OCPs and heavy metals were also compared with other previously published data. PMID:23533363

Regulation of brain copper homeostasis by the brain barrier systems: Effects of Fe-overload and Fe-deficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monnot, Andrew D.; Behl, Mamta; Ho, Sanna

2011-11-15

Maintaining brain Cu homeostasis is vital for normal brain function. The role of systemic Fe deficiency (FeD) or overload (FeO) due to metabolic diseases or environmental insults in Cu homeostasis in the cerebrospinal fluid (CSF) and brain tissues remains unknown. This study was designed to investigate how blood-brain barrier (BBB) and blood-SCF barrier (BCB) regulated Cu transport and how FeO or FeD altered brain Cu homeostasis. Rats received an Fe-enriched or Fe-depleted diet for 4 weeks. FeD and FeO treatment resulted in a significant increase (+ 55%) and decrease (- 56%) in CSF Cu levels (p < 0.05), respectively; however,more » neither treatment had any effect on CSF Fe levels. The FeD, but not FeO, led to significant increases in Cu levels in brain parenchyma and the choroid plexus. In situ brain perfusion studies demonstrated that the rate of Cu transport into the brain parenchyma was significantly faster in FeD rats (+ 92%) and significantly slower (- 53%) in FeO rats than in controls. In vitro two chamber Transwell transepithelial transport studies using primary choroidal epithelial cells revealed a predominant efflux of Cu from the CSF to blood compartment by the BCB. Further ventriculo-cisternal perfusion studies showed that Cu clearance by the choroid plexus in FeD animals was significantly greater than control (p < 0.05). Taken together, our results demonstrate that both the BBB and BCB contribute to maintain a stable Cu homeostasis in the brain and CSF. Cu appears to enter the brain primarily via the BBB and is subsequently removed from the CSF by the BCB. FeD has a more profound effect on brain Cu levels than FeO. FeD increases Cu transport at the brain barriers and prompts Cu overload in the CNS. The BCB plays a key role in removing the excess Cu from the CSF.« less

Enhanced reactivity of microscale Fe/Cu bimetallic particles (mFe/Cu) with persulfate (PS) for p-nitrophenol (PNP) removal in aqueous solution.

PubMed

Ji, Qingqing; Li, Jun; Xiong, Zhaokun; Lai, Bo

2017-04-01

In this study, batch experiments were conducted to examine the enhanced reactivity of microscale Fe/Cu bimetallic particles (mFe/Cu) with persulfate (PS) for p-nitrophenol (PNP) removal in aqueous solution. The key operating parameters (i.e., theoretical Cu mass loadings (TML Cu ), mFe/Cu dosage, PS dose, initial pH and temperature) were optimized by the batch experiments, respectively. The experimental data were followed well the pseudo-first-order kinetic model. Result reveals that refractory PNP (500 mg L -1 ) was effectively degraded by mFe/Cu-PS system with removal of 98.4% and k obs of 1.91 min -1 after only 3 min treatment under the optimal operating conditions. Moreover, compared with control experiments (i.e., mFe/Cu, microscale Fe 0 with PS (mFe 0 -PS), and PS alone), mFe/Cu-PS system exerted better performance for PNP removal due to the strong synergistic effect between PS and mFe/Cu. According to the analysis results of degradation kinetics of PNP, COD (chemical oxygen demand) removal, UV-vis absorption spectra and the intermediates formed, the results reveal that the PNP removal by mFe/Cu-PS system was mainly attributed to reduction accompanied slight oxidation. And based on the analysis of surface characteristics of mFe/Cu particles, it is further demonstrated that PS could enhance the reactivity of mFe/Cu through rapid corrosion of iron surface and decrease of surface passivation of mFe/Cu surface when the low molar ratio of PS to mFe/Cu (i.e., 1:43) was used in this study. These results also illustrates mFe/Cu-PS can be as a high efficient pretreatment technology for the removal of toxic refractory PNP from wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electronic States in EuCu2(Ge1-xSix)2 Based on the Doniach Phase Diagram

NASA Astrophysics Data System (ADS)

Iha, Wataru; Yara, Tomoyuki; Ashitomi, Yousuke; Kakihana, Masashi; Takeuchi, Tetsuya; Honda, Fuminori; Nakamura, Ai; Aoki, Dai; Gouchi, Jun; Uwatoko, Yoshiya; Kida, Takanori; Tahara, Time; Hagiwara, Masayuki; Haga, Yoshinori; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

2018-06-01

We succeeded in growing single crystals of EuCu2(Ge1-xSix)2 (x = 0-1) by the Bridgman method using a Mo crucible and measured the electrical resistivity, specific heat, magnetic susceptibility, and magnetization, together with the electrical resistivity under pressure. EuCu2(Ge1-xSix)2 compounds follow the Doniach phase diagram as a function of the x content. Namely, EuCu2(Ge1-xSix)2 compounds exhibit antiferromagnetic ordering at a Néel temperature of TN = 15 K in EuCu2Ge2 (x = 0), a maximum of TN ≃ 20 K at x ≃ 0.5, TN → 0 at x ≃ 0.7, and a moderate heavy-fermion state at x = 0.8 and 1 (EuCu2Si2). The present result is reasonably consistent with the previous studies carried out using arc-melted polycrystal samples. A similar change in the electronic states was also found to be realized under pressure P for x = 0, 0.45, and 0.6. The Néel temperature of TN = 15 K for x = 0 (EuCu2Ge2) increases slightly as a function of pressure, at a rate of dTN/dP = 3.0 K/GPa, reaches a maximum of TN = 27 K at around 5-6 GPa, decreases steeply, and becomes zero at a critical pressure of Pc ≃ 7 GPa. A moderate heavy-fermion state is realized at 8 GPa. Similar results were also obtained for x = 0.45 and 0.6, with smaller critical pressures of Pc ≃ 4.5 and 2 GPa, respectively.

Facile preparation of magnetic mesoporous Fe3O4/C/Cu composites as high performance Fenton-like catalysts

NASA Astrophysics Data System (ADS)

Li, Keyan; Zhao, Yongqin; Janik, Michael J.; Song, Chunshan; Guo, Xinwen

2017-02-01

Fe-Cu composites with different compositions and morphologies were synthesized by a hydrothermal method combined with precursor thermal transformation. γ-Fe2O3/CuO and α-Fe2O3/CuO were obtained by calcining the Fe and Cu tartrates under air atmosphere at 350 °C and 500 °C, respectively, while Fe3O4/C/Cu was obtained by calcining the tartrate precursor under N2 atmosphere at 500 °C. The Fe3O4/C/Cu composite possessed mesoporous structure and large surface area up to 133 m2 g-1. The Fenton catalytic performance of Fe3O4/C/Cu composite was closely related to the Fe/Cu molar ratio, and only proper amounts of Fe and Cu exhibited a synergistic enhancement in Fenton catalytic activity. Cu inclusion reduced Fe3+ to Fe2+, which accelerated the Fe3+/Fe2+ cycles and favored H2O2 decomposition to produce more hydroxyl radicals for methylene blue (MB) oxidation. Due to the photo-reduction of Fe3+ and Cu2+, the Fenton catalytic performance was greatly improved when amending with visible light irradiation in the Fe3O4/C/Cu-H2O2 system, and MB (100 mg L-1) was nearly removed within 60 min. The Fe3O4/C/Cu composite showed good recyclability and could be conveniently separated by an applied magnetic field. Compared with conventional methods for mesoporous composite construction, the thermolysis method using mixed metal tartrates as precursors has the advantages of easy preparation and low cost. This strategy provides a facile, cheap and green method for the synthesis of mesoporous composites as excellent Fenton-like catalysts, without any additional reductants or organic surfactants.

Major and trace elements in organically or conventionally produced milk.

PubMed

Hermansen, John E; Badsberg, Jens H; Kristensen, Troels; Gundersen, Vagn

2005-08-01

A total of 480 samples of milk from 10 organically and 10 conventionally producing dairy farms in Denmark and covering 8 sampling periods over 1 year (triplicate samplings) were analysed for 45 trace elements and 6 major elements by high-resolution inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry. Sampling, sample preparation, and analysis of the samples were performed under carefully controlled contamination-free conditions. The dairy cattle breeds were Danish-Holstein or Jersey. Sources of variance were quantified, and differences between production systems and breeds were tested. The major source of variation for most elements was week of sampling. Concentrations of Al, Cu, Fe, Mo, Rb, Se, and Zn were within published ranges. Concentrations of As, Cd, Cr, Mn and Pb were lower, and concentrations of Co and Sr were higher than published ranges. Compared with Holsteins, Jerseys produced milk with higher concentrations of Ba, Ca, Cu, Fe, Mg, Mn, Mo, P, Rh, and Zn and with a lower concentration of Bi. The organically produced milk, compared with conventionally produced milk, contained a significantly higher concentration of Mo (48 v. 37 ng/g) and a lower concentration of Ba (43 v. 62 ng/g), Eu (4 v. 7 ng/g), Mn (16 v. 20 ng/g) and Zn (4400 v. 5150 ng/g respectively). The investigation yielded typical concentrations for the following trace elements in milk, for which no or very few data are available: Ba, Bi, Ce, Cs, Eu, Ga, Gd, In, La, Nb, Nd, Pd, Pr, Rh, Sb, Sm, Tb, Te, Th, Ti, Tl, U, V, Y, and Zr.

Facile synthesis of CuFe2O4-Fe2O3 composite for high-performance supercapacitor electrode applications

NASA Astrophysics Data System (ADS)

Khan, Rashid; Habib, Muhammad; Gondal, Mohammed A.; Khalil, Adnan; Rehman, Zia Ur; Muhammad, Zahir; Haleem, Yasir A.; Wang, Changda; Wu, Chuan Qiang; Song, Li

2017-10-01

We report the synthesis of CuFe2O4-Fe2O3 composite material for efficient and highly stable supercapacitor electrode by using eco-friendly low-temperature co-precipitation method. The CuFe2O4-Fe2O3 composite demonstrated the highest specific capacitance of 638.24 F g-1 and excellent stability up to 2000 charge/discharge cycles. The achieved capacitance value is 16 times higher than that of pure CuFe2O4. The results revealed the extraordinary performance of CuFe2O4-Fe2O3 composite as supercapacitor electrode with excellent retention in comparison to CuFe2O4. The enhanced electrochemical activity of CuFe2O4-Fe2O3 composite is attributed to the synergistic effect which is responsible for redox coupling between Cu2+ and Fe3+ that has never been achieved by single component before.

The important role of polyvinylpyrrolidone and Cu on enhancing dechlorination of 2,4-dichlorophenol by Cu/Fe nanoparticles: Performance and mechanism study

NASA Astrophysics Data System (ADS)

Fang, Liping; Xu, Cuihong; Zhang, Wenbin; Huang, Li-Zhi

2018-03-01

The important role of polyvinylpyrrolidone (PVP) and Cu on the reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) by Cu/Fe bimetal nanoparticles has been investigated. The synthesized PVP coated Cu/Fe bimetal nanoparticles with different Cu/Fe ratios were systematically characterized by FTIR, XRD, TEM and magnetic hysteresis loops. The Cu/Fe ratio and the PVP loading were optimized for dechlorination performance, and the optimum ratio of PVP to Cu/Fe was found to be 0.35 and the content of Cu in Cu/Fe nanoparticles was 41%. The presence of PVP as a dispersant/stabilizer results in a highly-dispersed Cu/Fe NPs and increase the reactivity of Cu/Fe NPs for 2,4-DCP removal. The dechlorination rate was enhanced at lower pH and higher temperature conditions. The presence of humic acid, PO43-, NO3-, SO42- leads to a slightly decreased removal efficiency of 2,4-DCP. The magnetic property of PVP-Cu/Fe nanoparticles allows rapid magnetic separation of the catalysts after reaction. A galvanic corrosion model was proposed where iron corrodes and transfers electrons to Cu-rich catalytic regions of the nanoparticles, and finally accelerating the reduction efficiency of 2,4-DCP.

Comparative study on the reactivity of Fe/Cu bimetallic particles and zero valent iron (ZVI) under different conditions of N2, air or without aeration.

PubMed

Xiong, Zhaokun; Lai, Bo; Yang, Ping; Zhou, Yuexi; Wang, Juling; Fang, Shuping

2015-10-30

In order to further compare the degradation capacity of Fe(0) and Fe/Cu bimetallic system under different aeration conditions, the mineralization of PNP under different aeration conditions has been investigated thoroughly. The results show that the removal of PNP by Fe(0) or Fe/Cu system followed the pseudo-first-order reaction kinetics. Under the optimal conditions, the COD removal efficiencies obtained through Fe(0) or Fe/Cu system under different aeration conditions followed the trend that Fe/Cu (air)>Fe/Cu (N2: 0-30 min, air: 30-120 min)>control-Fe (air)>Fe/Cu (without aeration)>Fe/Cu (N2)>control-Fe (N2). It revealed that dissolved oxygen (DO) could improve the mineralization of PNP, and Cu could enhance the reactivity of Fe(0). In addition, the degradation of PNP was further analyzed by using UV-vis, FTIR and GC/MS, and the results suggest that Fe/Cu bimetallic system with air aeration could completely break the benzene ring and NO2 structure of PNP and could generate the nontoxic and biodegradable intermediate products. Meanwhile, most of these intermediate products were further mineralized into CO2 and H2O, which brought about a high COD removal efficiency (83.8%). Therefore, Fe/Cu bimetallic system with air aeration would be a promising process for toxic refractory industry wastewater. Copyright © 2015 Elsevier B.V. All rights reserved.

LOCAL MAGNETIC BEHAVIOR OF 54Fe in EuFe2As2 AND Eu0.5K0.5Fe2As2: MICROSCOPIC STUDY USING TIME DIFFERENTIAL PERTURBED ANGULAR DISTRIBUTION (TDPAD) SPECTROSCOPY

NASA Astrophysics Data System (ADS)

Mohanta, S. K.; Mishra, S. N.; Davane, S. M.; Layek, S.; Hossain, Z.

2013-12-01

In this paper, we report the time differential perturbed angular distribution measurements of 54Fe on a polycrystalline EuFe2As2 and Eu0.5K0.5Fe2As2. The hyperfine field and nuclear spin-relaxation rate are strongly temperature dependent in the paramagnetic state suggesting strong spin fluctuation in the parent compound. The local susceptibility show Curie-Weiss-like temperature dependence and Korringa-like relaxation in the tetragonal phase indicating the presence of local moment. In the orthorhombic phase, the hyperfine field behavior suggesting quasi two-dimensional magnetic ordering. The experimental results are in a good agreement with first-principle calculations based on density functional theory.

Multifunctional nanocomposite based on halloysite nanotubes for efficient luminescent bioimaging and magnetic resonance imaging

PubMed Central

Zhou, Tao; Jia, Lei; Luo, Yi-Feng; Xu, Jun; Chen, Ru-Hua; Ge, Zhi-Jun; Ma, Tie-Liang; Chen, Hong; Zhu, Tao-Feng

2016-01-01

A novel multifunctional halloysite nanotube (HNT)-based Fe3O4@HNT-polyethyleneimine-Tip-Eu(dibenzoylmethane)3 nanocomposite (Fe-HNT-Eu NC) with both photoluminescent and magnetic properties was fabricated by a simple one-step hydrothermal process combined with the coupling grafting method, which exhibited high suspension stability and excellent photophysical behavior. The as-prepared multifunctional Fe-HNT-Eu NC was characterized using various techniques. The results of cell viability assay, cell morphological observation, and in vivo toxicity assay indicated that the NC exhibited excellent biocompatibility over the studied concentration range, suggesting that the obtained Fe-HNT-Eu NC was a suitable material for bioimaging and biological applications in human hepatic adenocarcinoma cells. Furthermore, the biocompatible Fe-HNT-Eu NC displayed superparamagnetic behavior with high saturation magnetization and also functioned as a magnetic resonance imaging (MRI) contrast agent in vitro and in vivo. The results of the MRI tests indicated that the Fe-HNT-Eu NC can significantly decrease the T2 signal intensity values of the normal liver tissue and thus make the boundary between the normal liver and transplanted cancer more distinct, thus effectively improving the diagnosis effect of cancers. PMID:27698562

Multifunctional nanocomposite based on halloysite nanotubes for efficient luminescent bioimaging and magnetic resonance imaging.

PubMed

Zhou, Tao; Jia, Lei; Luo, Yi-Feng; Xu, Jun; Chen, Ru-Hua; Ge, Zhi-Jun; Ma, Tie-Liang; Chen, Hong; Zhu, Tao-Feng

A novel multifunctional halloysite nanotube (HNT)-based Fe 3 O 4 @HNT-polyethyleneimine-Tip-Eu(dibenzoylmethane) 3 nanocomposite (Fe-HNT-Eu NC) with both photoluminescent and magnetic properties was fabricated by a simple one-step hydrothermal process combined with the coupling grafting method, which exhibited high suspension stability and excellent photophysical behavior. The as-prepared multifunctional Fe-HNT-Eu NC was characterized using various techniques. The results of cell viability assay, cell morphological observation, and in vivo toxicity assay indicated that the NC exhibited excellent biocompatibility over the studied concentration range, suggesting that the obtained Fe-HNT-Eu NC was a suitable material for bioimaging and biological applications in human hepatic adenocarcinoma cells. Furthermore, the biocompatible Fe-HNT-Eu NC displayed superparamagnetic behavior with high saturation magnetization and also functioned as a magnetic resonance imaging (MRI) contrast agent in vitro and in vivo. The results of the MRI tests indicated that the Fe-HNT-Eu NC can significantly decrease the T 2 signal intensity values of the normal liver tissue and thus make the boundary between the normal liver and transplanted cancer more distinct, thus effectively improving the diagnosis effect of cancers.

Is PM(10) mass measurement a reliable index for air quality assessment? An environmental study in a geographical area of north-eastern Italy.

PubMed

Cozzi, F; Adami, G; Barbieri, P; Reisenhofer, E; Bovenzi, M

2008-09-01

The aim of this study was to measure the concentration of some metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Ti) in PM(10) samples collected in one urban and one industrial site and to assess that PM(10) total mass measurement may be not sufficient as air quality index due to its complex composition. Metals were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and differential pulsed anodic stripping voltammetry (DPASV). The measured concentrations were used to calculate the content of metals in the PM(10) total mass, and to estimate the enrichment factors and the correlations between PM(10), metal concentrations and meteorological data for the two sites. The mean PM10 concentration during the sampling period in the urban site exceeded the annual European Union (EU) standard (40 microg/m(3)) and, for some sampling days, the daily EU standard (50 microg/m(3)) was also exceeded. In opposite, both EU standards were never exceeded in the industrial site. The overall metal content was nearly double in the industrial site compared to the urban one, and the mean Ni concentration exceeded the EU annual limit value (10 ng/m(3)). The metals with the highest enrichment factor were Cd, Cu, Ni and Pb for both sites, suggesting a dominant anthropogenic source for these metals. Metal concentrations were very low and typical of rural background during Christmas holidays, when factories were closed. PM(10) total mass measurement is not a sufficient air quality index since the metal content of PM(10) is not related to its total mass, especially in sites with industrial activities. This measurement should be associated with the analysis of toxic metals.

Copper(II) sorption onto goethite, hematite and lepidocrocite: a surface complexation model based on ab initio molecular geometries and EXAFS spectroscopy

NASA Astrophysics Data System (ADS)

Peacock, Caroline L.; Sherman, David M.

2004-06-01

We measured the adsorption of Cu(II) onto goethite (α-FeOOH), hematite (α-Fe 2O 3) and lepidocrocite (γ-FeOOH) from pH 2-7. EXAFS spectra show that Cu(II) adsorbs as (CuO 4H n) n-6 and binuclear (Cu 2O 6H n) n-8 complexes. These form inner-sphere complexes with the iron (hydr)oxide surfaces by corner-sharing with two or three edge-sharing Fe(O,OH) 6 polyhedra. Our interpretation of the EXAFS data is supported by ab initio (density functional theory) geometries of analogue Fe 2(OH) 2(H 2O) 8Cu(OH) 4and Fe 3(OH) 4(H 2O) 10Cu 2(OH) 6 clusters. We find no evidence for surface complexes resulting from either monodentate corner-sharing or bidentate edge-sharing between (CuO 4H n) n-6 and Fe(O,OH) 6 polyhedra. Sorption isotherms and EXAFS spectra show that surface precipitates have not formed even though we are supersaturated with respect to CuO and Cu(OH) 2. Having identified the bidentate (FeOH) 2Cu(OH) 20 and tridentate (Fe 3O(OH) 2)Cu 2(OH) 30 surface complexes, we are able to fit the experimental copper(II) adsorption data to the reactions 3( FeOH)+2 Cu2++3 H2O=( Fe3O( OH) 2) Cu2( OH) 30+4 H+ and 2( FeOH)+ Cu2++2 H2O=( FeOH) 2Cu( OH) 20+2 H+. The two stability constants are similar for the three iron (hydr)oxide phases investigated.

Electronic structure of the gold/Bi2Sr2CaCu2O8 and gold/EuBa2Cu3O7 - delta interfaces as studied by photoemission spectroscopy

NASA Astrophysics Data System (ADS)

Dessau, D. S.; Shen, Z.-X.; Wells, B. O.; Spicer, W. E.; List, R. S.; Arko, A. J.; Bartlett, R. J.; Fisk, Z.; Cheong, S.-W.; Mitzi, D. B.; Kapitulnik, A.; Schirber, J. E.

1990-07-01

High-resolution photoemission has been used to probe the electronic structure of the gold/Bi2Sr2CaCu2O8 and gold/EuBa2Cu3O7-δ interface formed by a low-temperature (20 K) gold evaporation on cleaved high quality single crystals. We find that the metallicity of the EuBa2Cu3O7-δ substrate in the near surface region (˜5 Å) is essentially destroyed by the gold deposition, while the near surface region of Bi2Sr2CaCu2O8 remains metallic. This has potentially wide ranging consequences for the applicability of the different types of superconductors in real devices.

The interaction between dietary Fe, Cu and stress in Cu-67 retention and serum ceruloplasmin (Cp) activity in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pellett, L.; Kattelmann, K.; Zinn, K.

1991-03-15

The objectives of the study were to determine the effects of dietary Fe and stress on Cu-67 retention and serum Cp activity in the rat. A 2 {times} 2 {times} 2 factorial arrangement of treatments was utilized. Male Sprague Dawley weanling rats were fed AIN-76 diets ad lib containing 0.8 ppm Cu (CuD) or 5.7 ppm Cu (CuA) with 22.5 ppm Fe (FeA) or 280 ppm Fe (FeE). After 19 days, one-half of the animals of each treatment were stressed by an intramuscular injection of 0.1 ml turpentine/100 gm body weight. Forty-eight hours later, animals were gavaged with Cu-67 andmore » counted over a 7 day period in a whole body high resolution gamma counter. Cu-67 retention was 20% higher in CuD rats compared to CuA rats. There were no significant effects caused by Fe or stress or the interaction between these variables on Cu-67 retention. In rats fed FeE-CuA diets, serum Cp activity was significantly depressed compared to rats fed FeA-CuA diets. These reductions in the acute phase protein Cp, were 85% and 70% in nonstressed and stressed rats, respectively. The results of this study suggest that the negative interaction effects of excess Fe on Cu utilization does not occur at the site of Cu absorption, but within the body and specifically in the liver.« less

Functionalisation of lanthanide complexes via microwave-enhanced Cu(I)-catalysed azide-alkyne cycloaddition.

PubMed

Szíjjártó, Csongor; Pershagen, Elias; Borbas, K Eszter

2012-07-07

Cu(I)-catalysed azide-alkyne cycloaddition reactions were used to functionalise lanthanide(III)-complexes (Ln; La, Eu and Tb) incorporating alkyne or azide reactive groups. Microwave irradiation significantly accelerated the reactions, enabling full conversion to the triazole products in some cases in 5 min. Alkyl and aryl azides and alkyl and aryl alkynes could all serve as coupling partners. These reaction conditions proved efficient for cyclen-tricarboxylates and previously unreactive cyclen-tris-primary amide chelates. The synthesis of heterobimetallic (Eu/Tb, EuTb17 and Eu/La, EuLa17) and heterotrimetallic (Eu/La/Eu) complexes was achieved in up to 60% isolated yield starting from coumarin 2-appended alkynyl complexes Tb16 or La16 and an azido-Eu complex Eu4, and bis-alkynyl La-complex La5 and Eu4, respectively. EuTb17 displayed dual Eu(III) and Tb(III)-emission upon antenna-centred excitation.

Fe and Cu isotope mass balances in the human body

NASA Astrophysics Data System (ADS)

Balter, V.; Albarede, F.; Jaouen, K.

2011-12-01

The ranges of the Fe and Cu isotope compositions in the human body are large, i.e. ~3% and ~2%, respectively. Both isotopic fractionations appear to be mainly controlled by redox conditions. The Fe and Cu isotope compositions of the tissues analyzed so far plot on a mixing hyperbolae between a reduced and an oxidized metals pools. The reduced metals pool is composed by erythrocytes, where Fe is bounded to hemoglobin as Fe(II) and Cu to superoxide-dismutase as Cu(I). The oxidized metals pool is composed by hepatocytes, where Fe and Cu are stored as Fe(III) ferritin and as Cu(II) ceruloplasmine, respectively. The position of each biological component in the δ56Fe-δ65Cu diagram therefore reflects the oxidation state of Fe and Cu of the predominant metal carrier protein and allows to quantify Fe and Cu fluxes between organs using mass balance calculations. For instance, serum and clot Fe and Cu isotope compositions show that current biological models of erythropoiesis violates mass conservation requirements, and suggest hidden Fe and Cu pathways during red blood cells synthesis. The results also show that a coupled Fe-Cu strong gender isotopic effect is observed in various organs. The isotopic difference between men and women is unlikely to be due to differential dietary uptake or endometrium loss, but rather reflects the effect of menstrual losses and a correlative solicitation of hepatic stores. We speculate that thorough studies of the metabolism of stable isotopes in normal conditions is a prerequisite for the understanding of the pathological dysregulations.

Effects of Pd substitution on the thermoelectric and electronic properties of delafossite Cu{sub 1−x}Pd{sub x}FeO{sub 2} (x=0.01, 0.03 and 0.05)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruttanapun, Chesta, E-mail: chesta.ruttanapun@gmail.com

Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} (x=0.01, 0.03 and 005) delafossite was prepared by solid state reactions and was calcined/sintered at 1050 °C. The effect of Pd{sup 2+} substitution for the Cu{sup 1+} sites on the thermoelectric and electronic properties of Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} were investigated. The crystal structure, oxygen decomposition, thermoelectric and electronic properties were characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), Seebeck coefficient, electrical conductivity and thermal conductivity measurements. The characterization showed that Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} formed a hexagonal delafossite structure with R3−m symmetry. The existence of Pd{sup 2+}, Cu{sup 1+}, Cu{sup 2+}, Fe{sup 3+},more » Fe{sup 4+} and O was revealed from the XPS results. Confirmation of Pd{sup 2+} substitution for the Cu{sup 1+} sites occurred by increasing the c-axis in the lattice parameter with a Pd content. The O content intercalated at the center of the triangular Cu acted as a support to produce Cu{sup 2+} ions and was reduced with an increasing Pd content. The mixed valencies of Cu{sup 1+}/Cu{sup 2+} and Cu{sup 1+}/Pd{sup 2+} in the Cu layer changed the electrical conductivity and the Fe{sup 3+}/Fe{sup 4+} mixed valencies in the FeO{sub 6} layer caused the Seebeck coefficient to increase. Both the electrical conductivity and Seebeck coefficient for Pd contents of x=0.01 and 0.03 were higher than that of non-doped CuFeO{sub 2}. The low thermal conductivity of Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} resulted from the substitution of Pd, which has a large atomic mass, into structure. The Jonker plot indicated that the electronic properties displayed a degenerate density of states and that Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} was a semiconductor. A high ZT value of 0.055 was obtained for a Pd content of 0.03 at 950 K. The Pd{sup 2+} substitution for the Cu{sup 1+} sites influenced the thermoelectric and electronic properties of the delafossite Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} samples. - Graphical abstract: Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} (x=0.01, 0.03 and 005) delafossite was prepared by solid state reactions. The characterization showed that Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} formed a hexagonal delafossite structure with R3−m symmetry. The existence of Pd{sup 2+}, Cu{sup 1+}, Cu{sup 2+}, Fe{sup 3+}, Fe{sup 4+} and O was revealed from the XPS results. The O content intercalated at the center of the triangular Cu acted as a support to produce Cu{sup 2+} ions and was reduced with an increasing Pd content. The mixed valencies of Cu{sup 1+}/Cu{sup 2+} and Cu{sup 1+}/Pd{sup 2+} in the Cu layer changed the electrical conductivity and the Fe{sup 3+}/Fe{sup 4+} mixed valencies in the FeO{sub 6} layer caused the Seebeck coefficient to increase. Both the electrical conductivity and Seebeck coefficient for Pd contents of x=0.01 and 0.03 were higher than that of non-doped CuFeO{sub 2}. The low thermal conductivity of Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} resulted from the substitution of Pd, which has a large atomic mass, into structure. A high ZT value of 0.055 was obtained for a Pd content of 0.03 at 950 K. The Pd{sup 2+} substitution for the Cu{sup 1+} sites influenced the thermoelectric and electronic properties of the delafossite Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} samples. - Highlights: • New compound of Cu{sub 1−x}Pd{sub x}FeO{sub 2} (x=0.01, 0.03 and 0.05) forms phase of delafossite. • The compound displays p-type thermoelectric materials. • The Pd-substituted for Cu{sup 1+} sites forms Pd{sup 2+}. • Mixed valencies of Cu{sup +}/Cu{sup 2+}, Cu{sup +}/Pd{sup 2+} and Fe{sup 3+}/Fe{sup 4+} appear in the compound. • Large atomic mass of Pd-substituted causes low thermal conductivity.« less

Research progress in photolectric materials of CuFeS2

NASA Astrophysics Data System (ADS)

Jing, Mingxing; Li, Jing; Liu, Kegao

2018-03-01

CuFeS2 as a photoelectric material, there are many advantages, such as high optical absorption coefficient, direct gap semiconductor, thermal stability, no photo-recession effect and so on. Because of its low price, abundant reserves and non-toxic, CuFeS2 has attracted extensive attention of scientists.Preparation method of thin film solar cells are included that Electrodeposition, sputtering, thermal evaporation, thermal spraying method, co-reduction method.In this paper, the development of CuFeS2 thin films prepared by co-reduction method and co-reduction method is introduced.In this paper, the structure and development of solar cells, advantages of CuFeS2 as solar cell material, the structure and photoelectric properties and magnetic properties of CuFeS2, preparation process analysis of CuFeS2 thin film, research and development of CuFeS2 in solar cells is included herein. Finally, the development trend of CuFeS2 optoelectronic materials is analyzed and further research directions are proposed.

Far-infrared study of the mechanochemically synthesized Cu2FeSnS4 (stannite) nanocrystals

NASA Astrophysics Data System (ADS)

Trajic, J.; Romcevic, M.; Paunovic, N.; Curcic, M.; Balaz, P.; Romcevic, N.

2018-05-01

The analysis of the optical properties of mechanochemically synthesized stannite Cu2FeSnS4 nanocrystals has been performed using far-infrared spectroscopy. The Cu2FeSnS4 stannite nanocrystals were synthesized mechanochemically from elemental precursors Cu, Fe, Sn, and S. Milling time was 45, 60, 90 and 120 min. Reflectivity spectra were analyzed using the classical form of the dielectric function, which includes the phonon and the free carrier contribution. The influence of milling time on synthesis of stannite Cu2FeSnS4 is observed. Among the modes that are characteristic for the stannite Cu2FeSnS4, we registered the modes of binary phases of FeS and SnS. The total disappearance of the binary phases of FeS and SnS and forming pure Cu2FeSnS4 is observed when the milling time is 120 min. Effective permittivity of Cu2FeSnS4 and binary phases of FeS and SnS were modeled by Maxwell - Garnet approximation.

Study of crystal structure and unique photoluminescence properties of Eu2-xFexO3 (x = 0 - 0.5) orthoferrites

NASA Astrophysics Data System (ADS)

Dhilip, M.; Anbarasu, V.; Kumar, K. Saravana; Sivakumar, K.

2018-04-01

A series of Europium orthoferrites, Eu2-xFexO3 (x = 0 - 0.5) are successfully prepared by employing solid state reaction technique. The structural analysis through powder X-Ray diffraction technique reveals the multiphase formation of all the prepared compounds. Further, the unit cell visualization of all the prepared compounds confirms the change of crystal structure from cubic to orthorhombic phase. The crystal structure analysis confirms the typical framework of Eu - Fe - O chains with unprecedented ratio of Eu3+ and Fe3+ ions. The optical properties of prepared compounds are investigated using photoluminescence (PL) analysis. Upon excitation at 495 nm wavelength, the emission spectrum of prepared compounds exhibits a broad band in the range of 500-700nm with maximum intensity peak at 548 nm (Blue - 2.26eV). Hence, the substitution of Fe3+ ion yields with intrinsic blue photoluminescence (5D0 → 7F0) of Eu3+ and is easily shielded by the substitution of Fe3+ which may be due to the closer conduction band gap of Eu3+ (2.26 eV) with Fe3+ (2.67 eV). The schematic energy level diagram for Fe3+ in the Eu3+ host matrix has been proposed for the better understanding of photoluminescence processes. The variation of intensity of PL peak between 500 and 700 nm for the substitution of Fe in the range of x = 0 - 0.5 yields with interesting optical properties for exploring new phosphor materials for optoelectronic device fabrications.

Plankton copper requirements and uptake in the subarctic Northeast Pacific Ocean

NASA Astrophysics Data System (ADS)

Semeniuk, David M.; Cullen, Jay T.; Johnson, W. Keith; Gagnon, Katie; Ruth, Thomas J.; Maldonado, Maria T.

2009-07-01

We undertook the first measurements of metabolic Cu requirements (net Cu:C assimilation ratios) and steady-state Cu uptake rates (ρCu ss) of natural plankton assemblages in the northeast subarctic Pacific using the short-lived radioisotope 67Cu. Size-fractionated net Cu:C assimilation ratios varied ˜3 fold (1.35-4.21 μmol Cu mol C -1) among the stations along Line P, from high Fe coastal waters to the Fe-limited open ocean. The variability in Cu:C was comparable to biogenic Fe:C ratios in this region. As previously observed for Fe uptake, the bacterial size class accounted for half of the total particulate ρCu ss. Interestingly, carbon biomass-normalized rates of Fe uptake from the siderophore desferrioxamine B (DFB) (ρFe DFB; a physiological proxy for Fe-limitation) by the >20 μm size class were positively correlated with the intracellular net Cu:C assimilation ratios in this size class, suggesting that intracellular Cu requirements for large phytoplankton respond to increased Fe-limitation. At Fe-limited Ocean Station Papa (OSP), we performed short-term Cu uptake (ρCu L) assays to determine the relative bioavailability of Cu bound to natural and synthetic ligands. Like the volumetric ρCu ss measured along Line P, the bacterial size class was responsible for at least 50% of the total ρCu L. Uptake rates of Cu from the various organic complexes suggest that Cu uptake was controlled by the oxidation state of the metal and by the metal:ligand concentration ratio, rather than the concentration of inorganic species of Cu in solution. Collectively, these data suggest that Cu likely plays an important role in the physiology of natural plankton communities beyond the toxicological effects studied previously.

Colloidal GdVO4:Eu3+@SiO2 nanocrystals for highly selective and sensitive detection of Cu2+ ions

NASA Astrophysics Data System (ADS)

Liang, Yanjie; Noh, Hyeon Mi; Park, Sung Heum; Choi, Byung Chun; Jeong, Jung Hyun

2018-03-01

Nowadays, in view of health and safety demands, the controlled design of selective and sensitive sensors for Cu2+ detection is of considerable importance. Therefore, we construct herein core-shell colloidal GdVO4:Eu3+@SiO2 nanocrystals (NCs) as optical sensor for the detection of Cu2+, which were synthesized by a facile hydrothermal reaction and encapsulated with a uniform layer of ultrathin silica through a sol-gel strategy. The NCs present strong red emission due to energy transfer from VO43- groups to Eu3+ when exciting with ultraviolet (UV) light. This intense red emission from Eu3+ could be selectively quenched in the presence of Cu2+ in comparison to other metal ions and the limit of detection is as low as 80 nM in aqueous solution. It is revealed that the spectral overlap between the emission band of NCs and the absorption of Cu2+ accounts for this intriguing luminescence behavior. The detection ability is highly reversible by the addition of ethylenediaminetetraacetic acid (EDTA) with the recovery of almost 100% of the original luminescence. The luminescence quenching and recovery processes can be performed repeatedly with good sensing ability. These remarkable performances allow the colloidal GdVO4:Eu3+@SiO2 NCs a promising fluorescence chemosensor for detecting Cu2+ ions in aqueous solution.

Effects of dietary zinc, iron, and copper in layer feed on distribution of these elements in eggs, liver, excreta, soil, and herbage.

PubMed

Skrivan, M; Skrivanová, V; Marounek, M

2005-10-01

An experiment was conducted to evaluate the effect of dietary content and combinations of Zn, Fe, and Cu on deposition of these elements in egg components, liver, and excreta. Excreta were applied as a manure to a lawn, and 3 mo later soil and herbage samples were taken and analyzed. The experiment comprised 144 hens in 8 groups. The basal diet contained Zn, Fe, and Cu at 63.4, 92.8, and 9.0 mg/kg, respectively. It was supplemented with 1, 2, or 3 trace elements (inorganic forms) at 80 mg of Zn/kg, 120 mg of Fe/kg, and 25 mg of Cu/kg. Recovery of Zn, Fe, and Cu in eggs of hens fed the basal diet was 10.7, 9.8, and 4.4% of the alimentary intake, respectively. A Zn-Cu antagonism was observed; deposition of Zn in the yolk was significantly decreased by Cu addition and vice versa (P < 0.01). Supplementation of the basal diet with Fe increased Fe concentration in egg yolk and white by 6.3 and 2.2%, respectively. The combination of Fe with Zn and Cu, however, increased Fe concentration in the yolk and white by 36.7 and 34.9%, respectively (P < 0.01). The enrichment of eggs with the other elements was marginal (Cu) or absent (Zn). Effects of Zn, Fe, and Cu of the basal diet on liver concentrations of these elements were relatively small, and no antagonism between Zn and Cu was apparent. Supplementation of the basal diet with the combination of Zn and Fe, however, significantly decreased hepatic concentration of Cu. On the other hand, Cu supplementation significantly increased Fe concentration in livers of hens fed the Fe-supplemented diet (P < 0.01). Concentrations of Zn, Fe, and Cu in excreta were related to their dietary content. High concentrations of Zn, Fe, and Cu in excreta corresponded with limited deposition of the 3 elements in eggs and liver. Concentrations of Zn, Fe, and Cu in herbage correlated significantly with the supply of these elements by hen excreta into soil. The Zn supplied by hen excreta was more stable than Fe and Cu; thus Zn could accumulate in the soil.

The valence of Ru, Ce and Eu ions in the magneto-superconductor Eu 1.5Ce 0.5RuSr 2Cu 2O 10

NASA Astrophysics Data System (ADS)

Felner, I.; Asaf, U.; Godart, C.; Alleno, E.

1999-01-01

The superconducting (T c∼32 K) Eu 1.5Ce 0.5RuSr 2Cu 2O 10 (Ru-2122) material is also magnetically ordered (T M∼122 K) with TM≫ Tc. Superconductivity (SC) is confined to the CuO 2 planes, whereas magnetism is due to the Ru sublattice. Mossbauer spectroscopy performed at 90 and 300 K on 151Eu shows a single narrow line with an isomer shift=0.69(2) and a quadrupole splitting of 1.84 mm/s, indicating that the Eu ions are trivalent with a nonmagnetic J=0 ground state. This is in agreement with X-ray-absorption spectroscopy (XAS) taken at L III edges of Eu, Ce which shows that Eu is trivalent and Ce is tetravalent. XAS experiments at the K edge of Ru indicate that Ru is pentavalent. This indicates, that in the M-2122 system, SC exists only for pentavalent M ions such as Ta, Nb and Ru.

Using elemental profiles and stable isotopes to trace the origin of green coffee beans on the global market.

PubMed

Santato, Alessandro; Bertoldi, Daniela; Perini, Matteo; Camin, Federica; Larcher, Roberto

2012-09-01

A broad elemental profile incorporating 54 elements (Li, Be, B, Na, Mg, Al, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Y, Mo, Pd, Ag, Cd, Sn, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Tm, Yb, Re, Ir, Pt, Au, Hg, Tl, Pb, Bi and U) in combination with δ(2) H, δ(13) C, δ(15) N and δ(18) O was used to characterise the composition of 62 green arabica (Coffea arabica) and robusta (Coffea canephora) coffee beans grown in South and Central America, Africa and Asia, the four most internationally renowned areas of production. The δ(2) H, Mg, Fe, Co and Ni content made it possible to correctly assign 95% of green coffee beans to the appropriate variety. Canonical discriminant analysis, performed using δ(13) C, δ(15) N, δ(18) O, Li, Mg, P, K, Mn, Co, Cu, Se, Y, Mo, Cd, La and Ce correctly traced the origin of 98% of coffee beans. Copyright © 2012 John Wiley & Sons, Ltd.

Meta-omic signatures of microbial metal and nitrogen cycling in marine oxygen minimum zones

PubMed Central

Glass, Jennifer B.; Kretz, Cecilia B.; Ganesh, Sangita; Ranjan, Piyush; Seston, Sherry L.; Buck, Kristen N.; Landing, William M.; Morton, Peter L.; Moffett, James W.; Giovannoni, Stephen J.; Vergin, Kevin L.; Stewart, Frank J.

2015-01-01

Iron (Fe) and copper (Cu) are essential cofactors for microbial metalloenzymes, but little is known about the metalloenyzme inventory of anaerobic marine microbial communities despite their importance to the nitrogen cycle. We compared dissolved O2, NO3−, NO2−, Fe and Cu concentrations with nucleic acid sequences encoding Fe and Cu-binding proteins in 21 metagenomes and 9 metatranscriptomes from Eastern Tropical North and South Pacific oxygen minimum zones and 7 metagenomes from the Bermuda Atlantic Time-series Station. Dissolved Fe concentrations increased sharply at upper oxic-anoxic transition zones, with the highest Fe:Cu molar ratio (1.8) occurring at the anoxic core of the Eastern Tropical North Pacific oxygen minimum zone and matching the predicted maximum ratio based on data from diverse ocean sites. The relative abundance of genes encoding Fe-binding proteins was negatively correlated with O2, driven by significant increases in genes encoding Fe-proteins involved in dissimilatory nitrogen metabolisms under anoxia. Transcripts encoding cytochrome c oxidase, the Fe- and Cu-containing terminal reductase in aerobic respiration, were positively correlated with O2 content. A comparison of the taxonomy of genes encoding Fe- and Cu-binding vs. bulk proteins in OMZs revealed that Planctomycetes represented a higher percentage of Fe genes while Thaumarchaeota represented a higher percentage of Cu genes, particularly at oxyclines. These results are broadly consistent with higher relative abundance of genes encoding Fe-proteins in the genome of a marine planctomycete vs. higher relative abundance of genes encoding Cu-proteins in the genome of a marine thaumarchaeote. These findings highlight the importance of metalloenzymes for microbial processes in oxygen minimum zones and suggest preferential Cu use in oxic habitats with Cu > Fe vs. preferential Fe use in anoxic niches with Fe > Cu. PMID:26441925

Meta-omic signatures of microbial metal and nitrogen cycling in marine oxygen minimum zones.

PubMed

Glass, Jennifer B; Kretz, Cecilia B; Ganesh, Sangita; Ranjan, Piyush; Seston, Sherry L; Buck, Kristen N; Landing, William M; Morton, Peter L; Moffett, James W; Giovannoni, Stephen J; Vergin, Kevin L; Stewart, Frank J

2015-01-01

Iron (Fe) and copper (Cu) are essential cofactors for microbial metalloenzymes, but little is known about the metalloenyzme inventory of anaerobic marine microbial communities despite their importance to the nitrogen cycle. We compared dissolved O2, NO[Formula: see text], NO[Formula: see text], Fe and Cu concentrations with nucleic acid sequences encoding Fe and Cu-binding proteins in 21 metagenomes and 9 metatranscriptomes from Eastern Tropical North and South Pacific oxygen minimum zones and 7 metagenomes from the Bermuda Atlantic Time-series Station. Dissolved Fe concentrations increased sharply at upper oxic-anoxic transition zones, with the highest Fe:Cu molar ratio (1.8) occurring at the anoxic core of the Eastern Tropical North Pacific oxygen minimum zone and matching the predicted maximum ratio based on data from diverse ocean sites. The relative abundance of genes encoding Fe-binding proteins was negatively correlated with O2, driven by significant increases in genes encoding Fe-proteins involved in dissimilatory nitrogen metabolisms under anoxia. Transcripts encoding cytochrome c oxidase, the Fe- and Cu-containing terminal reductase in aerobic respiration, were positively correlated with O2 content. A comparison of the taxonomy of genes encoding Fe- and Cu-binding vs. bulk proteins in OMZs revealed that Planctomycetes represented a higher percentage of Fe genes while Thaumarchaeota represented a higher percentage of Cu genes, particularly at oxyclines. These results are broadly consistent with higher relative abundance of genes encoding Fe-proteins in the genome of a marine planctomycete vs. higher relative abundance of genes encoding Cu-proteins in the genome of a marine thaumarchaeote. These findings highlight the importance of metalloenzymes for microbial processes in oxygen minimum zones and suggest preferential Cu use in oxic habitats with Cu > Fe vs. preferential Fe use in anoxic niches with Fe > Cu.

Geochemistry of loess-paleosol sediments of Kashmir Valley, India: Provenance and weathering

NASA Astrophysics Data System (ADS)

Ahmad, Ishtiaq; Chandra, Rakesh

2013-04-01

Middle to Late Pleistocene loess-paleosol sediments of Kashmir Valley, India, were analyzed for major, trace and REE elements in order to determine their chemical composition, provenance and intensity of palaeo-weathering of the source rocks. These sediments are generally enriched with Fe2O3, MgO, MnO, TiO2, Y, Ni, Cu, Zn, Th, U, Sc, V and Co while contents of SiO2, K2O, Na2O, P2O5, Sr, Nb and Hf are lower than the UCC. Chondrite normalized REE patterns are characterized by moderate enrichment of LREEs, relatively flat HREE pattern (GdCN/YbCN = 1.93-2.31) and lack of prominent negative Eu anomaly (Eu/Eu* = 0.73-1.01, average = 0.81). PAAS normalized REE are characterized by slightly higher LREE, depleted HREE and positive Eu anomaly. Various provenance discrimination diagrams reveal that the Kashmir Loess-Paleosol sediments are derived from the mixed source rocks suggesting large provenance with variable geological settings, which apparently have undergone weak to moderate recycling processes. Weathering indices such as CIA, CIW and PIA values (71.87, 83.83 and 80.57 respectively) and A-CN-K diagram imply weak to moderate weathering of the source material.

Oxidative degradation of the antibiotic oxytetracycline by Cu@Fe3O4 core-shell nanoparticles.

PubMed

Pham, Van Luan; Kim, Do-Gun; Ko, Seok-Oh

2018-08-01

A core-shell nanostructure composed of zero-valent Cu (core) and Fe 3 O 4 (shell) (Cu@Fe 3 O 4 ) was prepared by a simple reduction method and was evaluated for the degradation of oxytetracycline (OTC), an antibiotic. The Cu core and the Fe 3 O 4 shell were verified by X-ray diffractometry (XRD) and transmission electron microscopy. The optimal molar ratio of [Cu]/[Fe] (1/1) in Cu@Fe 3 O 4 created an outstanding synergic effect, leading to >99% OTC degradation as well as H 2 O 2 decomposition within 10min at the reaction conditions of 1g/L Cu@Fe 3 O 4 , 20mg/L OTC, 20mM H 2 O 2 , and pH3.0 (and even at pH9.0). The OTC degradation rate by Cu@Fe 3 O 4 was higher than obtained using single nanoparticle of Cu or Fe 3 O 4 . The results of the study using radical scavengers showed that OH is the major reactive oxygen species contributing to the OTC degradation. Finally, good stability, reusability, and magnetic separation were obtained with approximately 97% OTC degradation and no notable change in XRD patterns after the Cu@Fe 3 O 4 catalyst was reused five times. These results demonstrate that Cu@Fe 3 O 4 is a novel prospective candidate for the pharmaceutical and personal care products degradation in the aqueous phase. Copyright © 2018 Elsevier B.V. All rights reserved.

Fabrication, structure, and properties of Fe3O4@C encapsulated with YVO4:Eu3+ composites

NASA Astrophysics Data System (ADS)

Shi, Jianhui; Tong, Lizhu; Liu, Deming; Yang, Hua

2012-03-01

The use of carbon shells offers many advantages in surface coating or surface modification due to their surface with activated carboxyl and carbonyl groups. In this study, the Fe3O4@C@YVO4:Eu3+ composites were prepared through a simple sol-gel process. Reactive carbon interlayer was introduced as a key component, which separates lanthanide-based luminescent component from the magnetite, more importantly, it effectively prevent oxidation of the Fe3O4 core during the whole preparation process. The morphology, structure, magnetic, and luminescent properties of the composites were characterized by transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction, X-ray photoelectron spectra, VSM, and photoluminescent spectrophotometer. As a result, the Fe3O4@C/YVO4:Eu3+ composites with well-crystallized and core-shell structure were prepared and the YVO4:Eu3+ luminescent layer decorating the Fe3O4@C core-shell microspheres are about 10 nm. In addition, the Fe3O4@C@YVO4:Eu3+ composites have the excellent magnetic and luminescent properties, which allow them great potential for bioapplications such as magnetic bioseparation, magnetic resonance imaging, and drug/gene delivery.

High spin polarization and the origin of unique ferromagnetic ground state in CuFeSb

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirohi, Anshu; Saha, Preetha; Gayen, Sirshendu

CuFeSb is isostructural to the ferro-pnictide and chalcogenide superconductors and it is one of the few materials in the family that are known to stabilize in a ferromagnetic ground state. Majority of the members of this family are either superconductors or antiferromagnets. Therefore, CuFeSb may be used as an ideal source of spin polarized current in spin-transport devices involving pnictide and the chalcogenide superconductors. However, for that the Fermi surface of CuFeSb needs to be sufficiently spin polarized. In this paper we report direct measurement of transport spin polarization in CuFeSb by spin-resolved Andreev reflection spectroscopy. From a number ofmore » measurements using multiple superconducting tips we found that the intrinsic transport spin polarization in CuFeSb is high (∼47%). In order to understand the unique ground state of CuFeSb and the origin of large spin polarization at the Fermi level, we have evaluated the spin-polarized band structure of CuFeSb through first principles calculations. Apart from supporting the observed 47% transport spin polarization, such calculations also indicate that the Sb-Fe-Sb angles and the height of Sb from the Fe plane are strikingly different for CuFeSb than the equivalent parameters in other members of the same family thereby explaining the origin of the unique ground state of CuFeSb.« less

Facile one-pot synthesis of cellulose nanocrystal-supported hollow CuFe2O4 nanoparticles as efficient catalyst for 4-nitrophenol reduction

NASA Astrophysics Data System (ADS)

Zhang, Sufeng; Zhao, Dongyan; Hou, Chen; Liang, Chen; Li, Hao

2018-06-01

A facile and efficient one-pot method for the synthesis of well-dispersed hollow CuFe2O4 nanoparticles (H-CuFe2O4 NPs) in the presence of cellulose nanocrystals (CNC) as the support was described. Based on the one-pot solvothermal condition control, magnetic H-CuFe2O4 NPs were in-situ grown on the CNC surface uniformly. TEM images indicated good dispersity of H-CuFe2O4 NPs with uniform size of 300 nm. The catalytic activity of H-CuFe2O4/CNC was tested in the catalytic reduction of 4-nitrophenol (4-NP) in aqueous solution. Compared with most CNC-based ferrite catalysts, H-CuFe2O4/CNC catalyst exhibited an excellent catalytic activity toward the reduction of 4-NP. The catalytic performance of H-CuFe2O4/CNC catalyst was remarkably enhanced with the rate constant of 3.24 s-1 g-1, which was higher than H-CuFe2O4 NPs (0.50 s-1 g-1). The high catalytic activity was attributed to the introduction of CNC and the special hollow mesostructure of H-CuFe2O4 NPs. In addition, the H-CuFe2O4/CNC catalyst promised good conversion efficiency without significant decrease even after 10 cycles, confirming relatively high stability. Because of its environmental sustainability and magnetic separability, H-CuFe2O4/CNC catalyst was shown to indicate that the ferrite nanoparticles supported on CNC were acted as a promising catalyst and exhibited potential applications in numerous ferrite based catalytic reactions.

Sorption Mechanisms of Cesium on Cu II2Fe II(CN) 6and Cu II3[Fe III(CN) 6] 2Hexacyanoferrates and Their Relation to the Crystalline Structure

NASA Astrophysics Data System (ADS)

Ayrault, S.; Jimenez, B.; Garnier, E.; Fedoroff, M.; Jones, D. J.; Loos-Neskovic, C.

1998-12-01

CuII2FeII(CN)6·xH2O and CuII3[FeIII(CN)6]2·xH2O can be prepared with reproducible chemical compositions and structures after careful washing. They have cubicFmoverline3mstructures with iron vacancies. In CuII2FeII(CN)6, copper occupies two different sites: Cu1 in position 4blinked to Fe through the CN groups, and Cu2 not linked to the CN groups and partially occupying the interstitial 24epositions. The second type of site is not present in CuII3[FeIII(CN)6]2. Sorption kinetics and isotherms were determined for cesium on both hexacyanoferrates by batch experiments. On CuII3[FeIII(CN)6]2, the maximum uptake is only 0.073 Cs/Fe (at./at.). On CuII2FeII(CN)6, the uptake reaches 1.5 Cs/Fe. The sorption kinetics include at least two steps: at1/2variation until approximately 72 h and then a slow evolution studied up to 6 months. The sorption mechanism is complex. The main process seems to be diffusion of ion pairs, followed by a reorganization of the solid, resulting in one or more new solid phases. The presence of the Cu2 site seems to play a favorable role in the sorption. Owing to its good midterm stability and the first rapid step of exchange, CuII2FeII(CN)6·xH2O seems to be one of the most promising compounds for the recovery of cesium from nuclear liquid wastes.

High strength-high conductivity Cu--Fe composites produced by powder compaction/mechanical reduction

DOEpatents

Verhoeven, John D.; Spitzig, William A.; Gibson, Edwin D.; Anderson, Iver E.

1991-08-27

A particulate mixture of Cu and Fe is compacted and mechanically reduced to form an "in-situ" Cu-Fe composite having high strength and high conductivity. Compaction and mechanical reduction of the particulate mixture are carried out at a temperature and time at temperature selected to avoid dissolution of Fe into the Cu matrix particulates to a harmful extent that substantially degrades the conductivity of the Cu-Fe composite.

Experimental investigation of inhomogeneities, nanoscopic phase separation, and magnetism in arc melted Fe-Cu metals with equal atomic ratio of the constituents

NASA Astrophysics Data System (ADS)

Hassnain Jaffari, G.; Aftab, M.; Anjum, D. H.; Cha, Dongkyu; Poirier, Gerald; Ismat Shah, S.

2015-12-01

Composition gradient and phase separation at the nanoscale have been investigated for arc-melted and solidified with equiatomic Fe-Cu. Diffraction studies revealed that Fe and Cu exhibited phase separation with no trace of any mixing. Microscopy studies revealed that immiscible Fe-Cu form dense bulk nanocomposite. The spatial distribution of Fe and Cu showed existence of two distinct regions, i.e., Fe-rich and Cu-rich regions. Fe-rich regions have Cu precipitates of various sizes and different shapes, with Fe forming meshes or channels greater than 100 nm in size. On the other hand, the matrix of Cu-rich regions formed strips with fine strands of nanosized Fe. Macromagnetic response of the system showed ferromagnetic behavior with a magnetic moment being equal to about 2.13 μB/ Fe atom and a bulk like negligible value of coercivity over the temperature range of 5-300 K. Anisotropy constant has been calculated from various laws of approach to saturation, and its value is extracted to be equal to 1350 J/m3. Inhomogeneous strain within the Cu and Fe crystallites has been calculated for the (unannealed) sample solidified after arc-melting. Annealed sample also exhibited local inhomogeneity with removal of inhomogeneous strain and no appreciable change in magnetic character. However, for the annealed sample phase separated Fe exhibited homogenous strain.

Chemical study of the metal-rich globular cluster NGC 5927

NASA Astrophysics Data System (ADS)

Mura-Guzmán, A.; Villanova, S.; Muñoz, C.; Tang, B.

2018-03-01

Globular clusters (GCs) are natural laboratories where stellar and chemical evolution can be studied in detail. In addition, their chemical patterns and kinematics can tell us to which Galactic structure (disc, bulge, halo or extragalactic) the cluster belongs to. NGC 5927 is one of most metal-rich GCs in the Galaxy and its kinematics links it to the thick disc. We present abundance analysis based on high-resolution spectra of seven giant stars. The data were obtained using Fibre Large Array Multi Element Spectrograph/Ultraviolet Echelle Spectrograph (UVES) spectrograph mounted on UT2 telescope of the European Southern Observatory. The principal objective of this work is to perform a wide and detailed chemical abundance analysis of the cluster and look for possible Multiple Populations (MPs). We determined stellar parameters and measured 22 elements corresponding to light (Na, Al), alpha (O, Mg, Si, Ca, Ti), iron-peak (Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn), and heavy elements (Y, Zr, Ba, Ce, Nd, Eu). We found a mean iron content of [Fe/H] = -0.47 ± 0.02 (error on the mean). We confirm the existence of MPs in this GC with an O-Na anti-correlation, and moderate spread in Al abundances. We estimate a mean [α/Fe] = 0.25 ± 0.08. Iron-peak elements show no significant spread. The [Ba/Eu] ratios indicate a predominant contribution from SNeII for the formation of the cluster.

Coercivity Recovery Effect of Sm-Fe-Cu-Al Alloy on Sm2Fe17N3 Magnet

NASA Astrophysics Data System (ADS)

Otogawa, Kohei; Asahi, Toru; Jinno, Miho; Yamaguchi, Wataru; Takagi, Kenta; Kwon, Hansang

2018-03-01

The potential of a Sm-Fe-Cu-Al binder for improvement of the magnetic properties of Sm2Fe17N3 was examined. Transmission electron microscope (TEM) observation of a Sm-Fe-Cu-Al alloy-bonded Sm2Fe17N3 magnet which showed high coercivity revealed that the Sm-Fe-Cu-Al alloy had an effect of removing the surface oxide layer of the Sm2 Fe17N3 grains. However, the Sm-Fe-Cu-Al binder was contaminated by carbon and nitrogen, which originated from the organic solvent used as the milling medium during pulverization. To prevent carbon and nitrogen contamination, the Sm-Fe- Cu-Al alloy was added directly on the surface of the Sm2Fe17N3 grains by sputtering. Comparing the recovered coercivity per unit amount of the added binder the uncontaminated binder-coated sample had a higher coercivity recovery effect than the milled binder-added sample. These results suggested that sufficient addition of the contamination-free Sm-Fe-Cu-Al binder has the possibility to reduce the amount of binder necessary to produce a high coercive Sm2Fe17N3 magnet.

Aluminum alloy anode materials for Li-ion batteries

NASA Astrophysics Data System (ADS)

Sun, Z. H.; Chen, Z. F.; Fu, Q. W.; Jiang, X. Y.

2017-03-01

Aluminum has larger theoretical capacity of 2235 mAh/g than that of graphite (372 mAh/g), but it has big disadvantages including shorter cycle life and higher irreversible capacity loss. Improving cycle performance can be obtained via alloying of aluminum. In this paper, two ternary aluminum alloy, Al7Cu2Fe and Al73Cu5Fe22 were prepared. The main phase of Al7Cu2Fe alloy was Al7Cu2Fe. The heat treatment increased the proportion of Al7Cu2Fe. The main phase of Al73Cu5Fe22 alloy was Al60Cu30Fe10. The heat treatment reduced the proportion of Al60Cu30Fe10. For two alloys, the heat treatment could increase discharge capacity compared with cast alloy. The discharge capacity was improved by 50%. The content of aluminum in alloys has little effect on improving cycle performance, and it has obvious influence on the phase structure of alloy with heat treatment.

Rapid removal of ultra-high-concentration p-nitrophenol in aqueous solution by microwave-enhanced Fe/Cu bimetallic particle (MW-Fe/Cu) system.

PubMed

Ren, Yi; Zhou, Jinfan; Pan, Zhicheng; Lai, Bo; Yuan, Donghai

2017-10-10

Ultra-high-concentration PNP-contained wastewaters are produced sometimes due to the wide application of this nitrophenolic compound in the chemical industry. However, there is a lack of appropriate technologies to rapidly pretreat the ultra-high-concentration wastewater. Therefore, a new microwave-enhanced Fe/Cu bimetallic particles (MW-Fe/Cu) system was developed to rapidly remove ultra-high-concentration PNP. First, the priority of the determinative parameters was obtained by orthogonal experiment. Based on this result, the effects of initial pH, microwave power, Fe/Cu dosage and initial PNP concentration on PNP removal were optimized thoroughly. Under the optimal conditions (i.e. initial pH = 1.0, MW power = 385 W, Fe/Cu dosage = 30 g/L and initial PNP concentration = 4000 mg/L), four control treatment systems (i.e. MW-Fe 0 , heating-Fe/Cu, MW alone and Fe/Cu alone system) were set up to compare with the MW-Fe/Cu system. The results suggest that high PNP removal (more than 99% with 2.5 min, k 1 /k 2  = 1.18/6.91 min -1 ) and COD removal (26.6% with 5 min treatment) could be obtained by the MW-Fe/Cu system, which were much superior to those obtained using the MW-Fe 0 (k 1 /k 2  = 0.62/2.21 min -1 ) and the heating-Fe/Cu system (k 1 /k 2  = 0.53/1.52 min -1 ). Finally, the determination of the intermediates of PNP degradation by HPLC indicated that the MW assistance process did not change the degradation pathway of PNP. This concludes that the new MW-Fe/Cu system was the promising technology for pretreatment of wastewater containing ultra-high-concentration toxic and refractory pollutants at a fairly short treatment time.

Ligand-hole localization in oxides with unusual valence Fe

PubMed Central

Chen, Wei-Tin; Saito, Takashi; Hayashi, Naoaki; Takano, Mikio; Shimakawa, Yuichi

2012-01-01

Unusual high-valence states of iron are stabilized in a few oxides. A-site-ordered perovskite-structure oxides contain such iron cations and exhibit distinct electronic behaviors at low temperatures, e.g. charge disproportionation (4Fe4+ → 2Fe3+ + 2Fe5+) in CaCu3Fe4O12 and intersite charge transfer (3Cu2+ + 4Fe3.75+ → 3Cu3+ + 4Fe3+) in LaCu3Fe4O12. Here we report the synthesis of solid solutions of CaCu3Fe4O12 and LaCu3Fe4O12 and explain how the instabilities of their unusual valence states of iron are relieved. Although these behaviors look completely different from each other in simple ionic models, they can both be explained by the localization of ligand holes, which are produced by the strong hybridization of iron d and oxygen p orbitals in oxides. The localization behavior in the charge disproportionation of CaCu3Fe4O12 is regarded as charge ordering of the ligand holes, and that in the intersite charge transfer of LaCu3Fe4O12 is regarded as a Mott transition of the ligand holes. PMID:22690318

Iron Sulfide Attenuates the Methanogenic Toxicity of Elemental Copper and Zinc Oxide Nanoparticles and their Soluble Metal Ion Analogs

PubMed Central

Gonzalez-Estrella, Jorge; Gallagher, Sara; Sierra-Alvarez, Reyes; Field, Jim A.

2016-01-01

Elemental copper (Cu0) and zinc oxide (ZnO) nanoparticle (NP) toxicity to methanogens has been attributed to the release of soluble metal ions. Iron sulfide (FeS) partially controls the soluble concentration of heavy metals and their toxicity in aquatic environments. Heavy metals displace the Fe from FeS forming poorly soluble metal sulfides in the FeS matrix. Therefore, FeS may be expected to attenuate the NP toxicity. This work assessed FeS as an attenuator of the methanogenic toxicity of Cu0 and ZnO NPs and their soluble salt analogs. The toxicity attenuation capacity of fine (25–75 µm) and coarse (500 to 1200 µm) preparations of FeS (FeS-f and FeS-c respectively) was tested in the presence of highly inhibitory concentrations of CuCl2, ZnCl2 Cu0 and ZnO NPs. FeS-f attenuated methanogenic toxicity better than FeS-c. The results revealed that 2.5× less FeS-f than FeS-c was required to recover the methanogenic activity to 50% (activity normalized to uninhibited controls). The results also indicated that a molar FeS-f/Cu0 NP, FeS-f/ZnO NP, FeS-f/ZnCl2, and FeS-f/CuCl2 ratio of 2.14, 2.14, 4.28, and 8.56 respectively, was necessary to recover the methanogenic activity to >75%. Displacement experiments demonstrated that CuCl2 and ZnCl2 partially displaced Fe from FeS. As a whole, the results indicate that not all the sulfide in FeS was readily available to react with the soluble Cu and Zn ions which may explain the need for a large stoichiometric excesses of FeS to highly attenuate Cu and Zn toxicity. Overall, this study provides evidence that FeS attenuates the toxicity caused by Cu0 and ZnO NPs and their soluble ion analogs to methanogens. PMID:26803736

High strength-high conductivity Cu-Fe composites produced by powder compaction/mechanical reduction

DOEpatents

Verhoeven, J.D.; Spitzig, W.A.; Gibson, E.D.; Anderson, I.E.

1991-08-27

A particulate mixture of Cu and Fe is compacted and mechanically reduced to form an ''in-situ'' Cu-Fe composite having high strength and high conductivity. Compaction and mechanical reduction of the particulate mixture are carried out at a temperature and time at temperature selected to avoid dissolution of Fe into the Cu matrix particulates to a harmful extent that substantially degrades the conductivity of the Cu-Fe composite. 5 figures.

Magnesium, Iron and Aluminum in LLNL Air Particulate and Rain Samples with Reference to Magnesium in Industrial Storm Water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esser, Bradley K.; Bibby, Richard K.; Fish, Craig

Storm water runoff from the Lawrence Livermore National Laboratory’s (LLNL’s) main site and Site 300 periodically exceeds the Discharge Permit Numeric Action Level (NAL) for Magnesium (Mg) under the Industrial General Permit (IGP) Order No. 2014-0057-DWQ. Of particular interest is the source of magnesium in storm water runoff from the site. This special study compares new metals data from air particulate and precipitation samples from the LLNL main site and Site 300 to previous metals data for storm water from the main site and Site 300 and alluvial sediment from the main site to investigate the potential source of elevatedmore » Mg in storm water runoff. Data for three metals (Mg, Iron {Fe}, and Aluminum {Al}) were available from all media; data for additional metals, such as Europium (Eu), were available from rain, air particulates, and alluvial sediment. To attribute source, this study compared metals concentration data (for Mg, Al, and Fe) in storm water and rain; metal-metal correlations (Mg with Fe, Mg with Al, Al with Fe, Mg with Eu, Eu with Fe, and Eu with Al) in storm water, rain, air particulates, and sediments; and metal-metal ratios ((Mg/Fe, Mg/Al, Al/Fe, Mg/Eu, Eu/Fe, and Eu/Al) in storm water, rain, air particulates and sediments. The results presented in this study are consistent with a simple conceptual model where the source of Mg in storm water runoff is air particulate matter that has dry-deposited on impervious surfaces and subsequently entrained in runoff during precipitation events. Such a conceptual model is consistent with 1) higher concentrations of metals in storm water runoff than in precipitation, 2) the strong correlation of Mg with Aluminum (Al) and Iron (Fe) in both storm water and air particulates, and 3) the similarity in metal mass ratios between storm water and air particulates in contrast to the dissimilarity of metal mass ratios between storm water and precipitation or alluvial sediment. The strong correlation of Mg with Fe and Al and of Fe with Al in storm water and air particulates and the strong association of Mg, Fe, and Al with Eu in air particulates strongly suggests that a dominant source of the Mg in storm water is associated with mineral phases of natural origin. These observations all point to Mg exceedances being associated with natural sources and processes and not with anthropogenic processes or pollutant sources.« less

Nitrate removal by Fe0/Pd/Cu nano-composite in groundwater.

PubMed

Liu, Hongyuan; Guo, Min; Zhang, Yan

2014-01-01

Nitrate pollution in groundwater shows a great threat to the safety of drinking water. Chemical reduction by zero-valent iron is being considered as a promising technique for nitrate removal from contaminated groundwater. In this paper, Fe0/Pd/Cu nano-composites were prepared by the liquid-phase reduction method, and batch experiments of nitrate reduction by the prepared Fe0/Pd/Cu nano-composites under various operating conditions were carried out. It has been found that nano-Fe0/Pd/Cu composites processed dual functions: catalytic reduction and chemical reduction. The introduction of Pd and Cu not only improved nitrate removal rate, but also reduced the generation of ammonia. Nitrate removal rate was affected by the amount of Fe0/Pd/Cu, initial nitrate concentration, solution pH, dissolved oxygen (DO), reaction temperature, the presence of anions, and organic pollutant. Moreover, nitrate reduction by Fe0/Pd/Cu composites followed the pseudo-first-order reaction kinetics. The removal rate of nitrate and total nitrogen were about 85% and 40.8%, respectively, under the reaction condition of Fe-6.0%Pd-3.0%Cu amount of 0.25 g/L, pH value of 7.1, DO of 0.42 mg/L, and initial nitrate concentration of 100 mg/L. Compared with the previous studies with Fe0 alone or Fe-Cu, nano-Fe-6%Pd-3%Cu composites showed a better selectivity to N2.

Seebeck Coefficient of Cation-Substituted Disulfides CuCr1-x Fe x S2 and Cu1-x Fe x CrS2

NASA Astrophysics Data System (ADS)

Korotaev, Evgeniy V.; Syrokvashin, Mikhail M.; Filatova, Irina Yu.; Pelmenev, Konstantin G.; Zvereva, Valentina V.; Peregudova, Natalya N.

2018-03-01

The effect of cation substitution on the Seebeck coefficient of CuCr1-x Fe x S2 (x = 0 to 0.30) and Cu1-x Fe x CrS2 (x = 0 to 0.03) in the temperature range of 100 K to 450 K has been investigated. Increasing iron concentration led to a metal-insulator transition which suppressed the thermoelectric power. However, for low iron concentration (x < 0.03), the Seebeck coefficient of CuCr1-x Fe x S2 and Cu1-x Fe x CrS2 exceeded the values for the undoped copper-chromium disulfide matrix CuCrS2 at temperature below 300 K.

Coercivity enhancement of Nd-Fe-B hot-deformed magnets by the eutectic grain boundary diffusion process using Nd-Ga-Cu and Nd-Fe-Ga-Cu alloys

NASA Astrophysics Data System (ADS)

Liu, Lihua; Sepehri-Amin, H.; Sasaki, T. T.; Ohkubo, T.; Yano, M.; Sakuma, N.; Kato, A.; Shoji, T.; Hono, K.

2018-05-01

Nd80Ga15Cu5 and Nd62Fe14Ga20Cu4 alloys were used as diffusion sources for the eutectic grain boundary diffusion process, applying to 4 mm-thick Nd-Fe-B hot-deformed magnets. Both samples showed nearly same coercivity of 2.2 T, while the sample processed with Nd62Fe14Ga20Cu4 showed smaller remanence deterioration from 1.50 T to 1.30 T, in contrast to that of the sample processed with Nd80Ga15Cu5 to 1.08 T. Mr/Ms of the initial sample and the samples processed with Nd62Fe14Ga20Cu4 and Nd80Ga15Cu5 were 0.946, 0.934 and 0.917, respectively, suggesting that the sample processed with Nd62Fe14Ga20Cu4 retains stronger c-axis texture after the diffusion process. Nd-rich phases with Ia3 ¯ and fcc structures were observed in the sample processed with Nd80Ga15Cu5, while the Nd-rich phases with the Ia3 ¯ and hcp structures were found in the sample processed with Nd62Fe14Ga20Cu4, all of which are the phases commonly observed in Nd-Fe-B sintered magnets.

Mechanism insight of pollutant degradation and bromate inhibition by Fe-Cu-MCM-41 catalyzed ozonation.

PubMed

Chen, Weirui; Li, Xukai; Tang, Yiming; Zhou, Jialu; Wu, Dan; Wu, Yin; Li, Laisheng

2018-03-15

A flexible catalyst, Fe-Cu-MCM-41, was employed to enhance diclofenac (DCF) mineralization and inhibit bromate formation in catalytic ozonation process. Greater TOC removal was achieved in Fe-Cu-MCM-41/O 3 process (78%) than those in Fe-MCM-41/O 3 (65%), Cu-MCM-41/O 3 (73%) and sole ozonation (42%). But it was interesting that both Cu-MCM-41/O 3 and Fe-MCM-41/O 3 achieved 93% bromate inhibition efficiency, only 71% inhibition efficiency was observed in Fe-Cu-MCM-41/O 3 . Influence of pH, TBA/NaHSO 3 and detection of by-products were conducted to explore the mechanism. By Pyridine adsorption-IR and XPS, a relationship was found among activity of catalysts, Lewis acid sites and electron transfer effect between Fe (II/III) and Cu (I/II). Fe-Cu-MCM-41 promoted ozone decomposition to generate OH, which accounted for enhanced DCF mineralization. The consumption of aqueous O 3 also suppressed the oxidative of Br - and HBrO/Br - . More HBrO/BrO - accumulated in catalytic ozonation process and less bromate generated. Bromate formation in Fe-Cu-MCM-41/O 3 process was sensitive with pH value, the acidic condition was not favor for bromate formation. Both DCF mineralization and bromate inhibition were influenced by surface reaction. Moreover, Fe-Cu-MCM-41 showed excellent catalytic performance in suppressing the accumulation of carboxylic acid, especially for oxalic acid. Nearly no oxalic acid was detected during Fe-Cu-MCM-41/O 3 process. Copyright © 2017 Elsevier B.V. All rights reserved.

Exploring the mechanism and kinetics of Fe-Cu-Ag trimetallic particles for p-nitrophenol reduction.

PubMed

Yuan, Yue; Yuan, Donghai; Zhang, Yunhong; Lai, Bo

2017-11-01

Preparation conditions of Fe-Cu-Ag trimetallic particles were optimized by single-factor and response surface methodology (RSM) batch experiments to obtain high-reactive Fe 0 -based materials for p-nitrophenol (PNP) removal. Under the optimal conditions (i.e., Fe 0 dosage of 34.86 g L -1 , theoretical Cu mass loading of 81.87 mg Cu/g Fe, theoretical Ag mass loading of 1.15 mg Ag/g Fe, and preparation temperature of 52.1 °C), the actual rate constant (k obs ) of PNP reduction in 5 min was 1.64 min -1 , which shows a good agreement between the model prediction (1.85 min -1 ) of RSM and the experimental data. Furthermore, the high reactivity of Fe 0 -based trimetals was mainly attributed to the plating order of transition metals (i.e., Ag and Cu). Furthermore, we propose a new theory that the pyramid trimetallic structure of Fe-Cu-Ag could improve the electron transport and create active sites with high electron density at the surface (Ag layer) that could enhance the generation of surface-bonded atomic hydrogen ([H] abs ) or the direct reduction of pollutant. Moreover, Fe-Cu-Ag trimetallic particles were characterized by SEM, EDS, and XPS, which also could confirm the proposed theory. In addition, the leached Cu 2+ (<10 μg L -1 ) and Ag + (below detection limits) in Fe-Cu-Ag system could be neglected completely, which suggests that Fe-Cu-Ag is reliable, safe, and environment friendly. Therefore, Fe-Cu-Ag trimetallic system would be promising for the removal of pollutants from industrial wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

``Loose spins'' in Fe/Cu/Fe(001) structures

NASA Astrophysics Data System (ADS)

Heinrich, B.; Celinski, Z.; Liao, L. X.; From, M.; Cochran, J. F.

1994-05-01

Slonczewski recently proposed a model for the exchange coupling between ferromagnetic layers separated by a nonferromagnetic spacer based on the concept of ``loose spins.'' ``Loose spins'' contribute to the total exchange energy. We have studied the role of ``loose spins'' in bcc Fe/Cu/Fe(001) structures. bcc Fe/Cu/Fe(001) trilayers deposited at room temperature were investigated extensively in our previous studies. In our ``loose spin'' studies, the Fe was added inside the Cu interlayer. Several structures were atomically engineered in order to test the behavior of ``loose spins:'' One additional atomic layer of an (Fe+Cu) alloy were located in appropriate positions in a Cu spacer. The bilinear and biquadratic exchange coupling in the above structures was quantitatively studied with FMR in the temperature range 77-370 K and with MOKE at RT.

Determination of trace element level in different tissues of the leaping mullet (Liza saliens, Mugilidae) collected from Caspian Sea.

PubMed

Ebrahimzadeh, Mohammad Ali; Eslami, Shahram; Nabavi, Seyed Fazel; Nabavi, Seyed Mohammad

2011-12-01

The concentrations of Cr, Cu, Fe, Mn, Ni, Pb, Cd, and Zn were determined in the brain, heart, liver, gill, gonad, spleen, kidney, and red and white muscles of Liza saliens (leaping mullet). Trace element levels in fish samples were analyzed by flame atomic absorption spectrometry. Among the non-essential metals, the levels of Ni and Pb in the tissues were higher than limits for fish proposed by FAO/WHO, EU, and TFC. Generally, the levels of the non-essential metals were much higher than those of manganese in the red and white muscles. Fe distribution pattern in tissues was in order of spleen > liver > heart > gill > brain > kidney > gonad > red muscle > white muscle. Red muscle was not within the safe limits for human consumption because non-essential metal (Ni, Pb) contents were higher than standard limits.

Rapid synthesis of Fe-doped CuO-Ce0.8Zr0.2O2 catalysts for CO preferential oxidation in H2-rich streams: Effect of iron source and the ratio of Fe/Cu

NASA Astrophysics Data System (ADS)

Wang, Jing; Han, Caiyun; Gao, Xiaoya; Lu, Jichang; Wan, Gengpin; He, Dedong; Chen, Ran; Chen, Kezhen; He, Sufang; Luo, Yongming

2017-03-01

A facile route (urea grind combustion method) is described for the rapid synthesis of Fe-doped Cu-Ce-Zr catalysts within 30 min through simple grinding and combustion. The effects of iron source and Fe/Cu mass ratio on the performances of the catalysts for CO preferential oxidation (CO-PROX) are evaluated. The influences of H2O, CO2, and their mixture on the activity as well as stability of the catalysts are also investigated. The samples are characterized by XRD, N2 adsorption-desorption, H2-TPR, TEM, Raman and XPS. Fe(NO3)3 is found to be superior to FeCl3 and Fe2(SO4)3 as the iron source for Fe-CuCZ catalyst. Among the different synthesized catalysts, 1/10Fe(N)-CuCZ is found to be the most active catalyst, indicating that the optimal Fe/Cu mass ratio is 1/10. The influences of H2O, CO2, and H2O + CO2 on the catalytic performance of 1/10Fe(N)-CuCZ are in the order of CO2 < CO2 + H2O < H2O. 1/10Fe(N)-CuCZ exhibits excellent stability during a 228 h time-on-stream test. 1/10Fe(N)-CuCZ shows the highest catalytic activity and excellent stability even in the presence of H2O and CO2. The excellent catalytic performance can be attributed to the synergy between the highly dispersed copper species and ceria, as well as the formation of more oxygen vacancies and reduced copper species.

[Fluorescence property of a chemical probe for naked-eye and detection of Fe3+].

PubMed

Song, Yu-Min; Ma, Xin-Xian; Yang, Wu

2012-12-01

A higher selective and sensitive probe for the detection of Fe(III) in aqueous media was made using 2,4-Diisocyanatotoluene (TDI) as a bridge to couple Fe3 O4 nanoparticles(NPs) and Rhodamine-6G hydrazide. The characterization of composite materials with Infrared spectra(IR), Thermal Gravimetric analysis(TGA) and Transmission Emission Microscopy(TEM) points to the graft of Rhodamine-6G hydrazide onto the surface of the Fe3O4. The obvious color change of the probe solution from light grey to pink upon the addition of Fe3+ demonstrated the probe could be used for "naked-eye" detection of Fe3+ in water at pH 7. The presence of 1 equivalent (10 micromol x L(-1) microm) of each of these metal ions, including Mn2+, Ni2+, Y2+, Eu3+, Ce3+, La3+, Pr3+, Cd2+, Cr3+, Sm3+, Fe2+, Cu2+ and Zn2+ ions, did not demonstrate any obvious fluorescence change of the probe water solution, which confirmed the probe was a probe with remarkable selectivity for Fe3+. And the fluorescence images of HeLa cells in physiological solutions after incubation with Fe3+ and then further incubated with the probe leading to a strong intracellular fluorescence, which suggested the probe could penetrate the HeLa cell membrane and could respond to Fe3+ in intracellular within living cells.

Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program. II. Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu

NASA Astrophysics Data System (ADS)

Delgado Mena, E.; Tsantaki, M.; Adibekyan, V. Zh.; Sousa, S. G.; Santos, N. C.; González Hernández, J. I.; Israelian, G.

2017-10-01

Aims: To understand the formation and evolution of the different stellar populations within our Galaxy it is essential to combine detailed kinematical and chemical information for large samples of stars. The aim of this work is to explore the chemical abundances of neutron capture elements which are a product of different nucleosynthesis processes taking place in diverse objects in the Galaxy, such as massive stars, asymptotic giant branch (AGB) stars and supernovae (SNe) explosions. Methods: We derive chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu for a large sample of more than 1000 FGK dwarf stars with high-resolution (R 115 000) and high-quality spectra from the HARPS-GTO program. The abundances are derived by a standard local thermodynamic equilibrium (LTE) analysis using measured equivalent widths (EWs) injected to the code MOOG and a grid of Kurucz ATLAS9 atmospheres. Results: We find that thick disc stars are chemically disjunct for Zn and Eu and also show on average higher Zr but lower Ba and Y than the thin disc stars. We also discovered that the previously identified high-α metal-rich population is also enhanced in Cu, Zn, Nd, and Eu with respect to the thin disc but presents lower Ba and Y abundances on average, following the trend of thick disc stars towards higher metallities and further supporting the different chemical composition of this population. By making a qualitative comparison of O (pure α), Mg, Eu (pure r-process), and s-process elements we can distinguish between the contribution of the more massive stars (SNe II for α and r-process elements) and the lower mass stars (AGBs) whose contribution to the enrichment of the Galaxy is delayed, due to their longer lifetimes. The ratio of heavy-s to light-s elements of thin disc stars presents the expected behaviour (increasing towards lower metallicities) and can be explained by a major contribution of low-mass AGB stars for s-process production at disc metallicities. However, the opposite trend found for thick disc stars suggests that intermediate-mass AGB stars play an important role in the enrichment of the gas from where these stars formed. Previous works in the literature also point to a possible primary production of light-s elements at low metallicities to explain this trend. Finally, we also find an enhancement of light-s elements in the thin disc at super-solar metallicities which could be caused by the contribution of metal-rich AGB stars. Conclusions: This work proves the utility of homogeneous and high-quality data of modest sample sizes. We find some interesting trends that might help to differentiate thin and thick disc population (such as [Zn/Fe] and [Eu/Fe] ratios) and that can also provide useful constraints for Galactic chemical evolution models of the different populations in the Galaxy. Based on observations collected at the La Silla Observatory, ESO (Chile), with the HARPS spectrograph at the 3.6 m ESO telescope (ESO runs ID 72.C—0488, 082.C—0212, and 085.C—0063).Full Tables 1 and 3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A94

Controlling Magnetism via Transition Metal Exchange in the Series of Intermetallics Eu( T1, T2)5In ( T = Cu, Ag, Au)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mudring, Anja -Verena; Smetana, Volodymyr; Pecharsky, Vitalij K.

Three series of intermetallic compounds Eu( T1, T2) 5In (T = Cu, Ag, Au) have been investigated in full compositional ranges. Single crystals of all compounds have been obtained by self-flux and were analyzed by single X-ray diffraction revealing the representatives to fall into two structure types: CeCu 6 ( oP28, Pnma, a = 8.832(3)–9.121(2) Å, b = 5.306(2)–5.645(1) Å, c = 11.059(4)–11.437(3) Å, V = 518.3(3)–588.9(2) Å 3) and YbMo2Al4 ( t I14, I4/ mmm, a = 5.417(3)–5.508(1) Å, c = 7.139(2)– 7.199(2) Å, V = 276.1(2)–285.8(1) Å 3). The structural preference was found to depend on the cation/anionmore » size ratio, while the positional preference within the CeCu 6 type structure shows an apparent correlation with the anion size. Chemical compression, hence, a change in cell volume, which occurs upon anion substitution appears to be the main driving force for the change of magnetic ordering. While EuAg 5In shows antiferromagnetic behavior at low temperatures, mixing Cu and Au within the same type of structure results in considerable changes in the magnetism. The Eu(Cu,Au) 5In alloys with CeCu 6 structure show complex magnetic behaviors and strong magnetic field-induced spin-reorientation transition with the critical field of the transition being dependent on Cu/Au ratio. The alloys adopting the YbMo 2Al 4 type structure are ferromagnets exhibiting unusually high magnetic moments. The heat capacity of EuAu 2.66Cu 2.34In reveals a double-peak structure evolving with the magnetic field. Furthermore, low-temperature X-ray powder diffraction does not show a structural transition.« less

Controlling Magnetism via Transition Metal Exchange in the Series of Intermetallics Eu( T1, T2)5In ( T = Cu, Ag, Au)

DOE PAGES

Mudring, Anja -Verena; Smetana, Volodymyr; Pecharsky, Vitalij K.; ...

2017-11-24

Three series of intermetallic compounds Eu( T1, T2) 5In (T = Cu, Ag, Au) have been investigated in full compositional ranges. Single crystals of all compounds have been obtained by self-flux and were analyzed by single X-ray diffraction revealing the representatives to fall into two structure types: CeCu 6 ( oP28, Pnma, a = 8.832(3)–9.121(2) Å, b = 5.306(2)–5.645(1) Å, c = 11.059(4)–11.437(3) Å, V = 518.3(3)–588.9(2) Å 3) and YbMo2Al4 ( t I14, I4/ mmm, a = 5.417(3)–5.508(1) Å, c = 7.139(2)– 7.199(2) Å, V = 276.1(2)–285.8(1) Å 3). The structural preference was found to depend on the cation/anionmore » size ratio, while the positional preference within the CeCu 6 type structure shows an apparent correlation with the anion size. Chemical compression, hence, a change in cell volume, which occurs upon anion substitution appears to be the main driving force for the change of magnetic ordering. While EuAg 5In shows antiferromagnetic behavior at low temperatures, mixing Cu and Au within the same type of structure results in considerable changes in the magnetism. The Eu(Cu,Au) 5In alloys with CeCu 6 structure show complex magnetic behaviors and strong magnetic field-induced spin-reorientation transition with the critical field of the transition being dependent on Cu/Au ratio. The alloys adopting the YbMo 2Al 4 type structure are ferromagnets exhibiting unusually high magnetic moments. The heat capacity of EuAu 2.66Cu 2.34In reveals a double-peak structure evolving with the magnetic field. Furthermore, low-temperature X-ray powder diffraction does not show a structural transition.« less

Note: Resonance magnetoelectric interactions in laminate of FeCuNbSiB and multilayer piezoelectric stack for magnetic sensor

NASA Astrophysics Data System (ADS)

Li, Jianqiang; Lu, Caijiang; Xu, Changbao; Zhong, Ming

2015-09-01

This paper develops a simple miniature magnetoelectric (ME) laminate FeCuNbSiB/PZT-stack made up of magnetostrictive Fe73.5Cu1Nb3Si13.5B9 (FeCuNbSiB) foils and piezoelectric Pb(Zr, Ti)O3 (PZT) multilayer stack vibrator. Resonant ME interactions of FeCuNbSiB/PZT-stack with different layers of FeCuNbSiB foil (L) are investigated in detail. The experimental results show that the ME voltage coefficient reaches maximum value of 141.5 (V/cm Oe) for FeCuNbSiB/PZT-stack with L = 6. The AC-magnetic sensitivities can reach 524.29 mV/Oe and 1.8 mV/Oe under resonance 91.6 kHz and off-resonance 1 kHz, respectively. The FeCuNbSiB/PZT-stack can distinguish small dc-magnetic field of ˜9 nT. The results indicate that the proposed ME composites are very promising for the cheap room-temperature magnetic field sensing technology.

Copper nanocluster coupling europium as an off-to-on fluorescence probe for the determination of phosphate ion in water samples.

PubMed

Cao, Haiyan; Chen, Zhaohui; Huang, Yuming

2015-10-01

This paper reports an "off-to-on" fluorescence (FL) probe for sensitively and selectively detecting phosphate ions (Pi's). Fabrication of the probe was based on the competition between Pi's and tannic acid-stabilized copper nanoclusters (TA-Cu NCs) for Eu(3+) binding. The addition of Eu(3+) ions to TA-Cu NCs triggered the aggregation of TA-Cu NCs, which quenched the FL of TA-Cu NCs. After Pi addition, the aggregated TA-Cu NCs solubilized into the aqueous solution to facilitate the Pi-triggered dispersion of TA-Cu NCs. This phenomenon was due to the stronger binding ability between Pi's and Eu(3+) than that between TA and Eu(3+), leading to FL recovery of Cu NCs. The degree of redispersion of TA-Cu NCs was directly related to Pi concentration. Thus, Pi concentration can be quantitatively determined by the change in FL of the TA-Cu NCs dispersion. Under the optimized conditions, the change in FL presented a linear relationship with Pi concentration from 0.07 μmol L(-1) to 80 μmol L(-1). The limit of detection for Pi was 9.6×10(-3) μmol L(-1) at a signal-to-noise ratio of 3. For Pi determination in real samples, only 1 mL water sample was needed. The proposed probe was highly sensitive, free from the interference of other common species in aqueous media, and particularly useful for the fast and simple diagnosis of water-eutrophication extent. Copyright © 2015 Elsevier B.V. All rights reserved.

Enhancement of spin-Seebeck effect by inserting ultra-thin Fe{sub 70}Cu{sub 30} interlayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kikuchi, D., E-mail: d.kikuchi@imr.tohoku.ac.jp; WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577; Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai 980-8577

2015-02-23

We report the longitudinal spin-Seebeck effects (LSSEs) for Pt/Fe{sub 70}Cu{sub 30}/BiY{sub 2}Fe{sub 5}O{sub 12} (BiYIG) and Pt/BiYIG devices. The LSSE voltage was found to be enhanced by inserting an ultra-thin Fe{sub 70}Cu{sub 30} interlayer. This enhancement decays sharply with increasing the Fe{sub 70}Cu{sub 30} thickness, suggesting that it is not due to bulk phenomena, such as a superposition of conventional thermoelectric effects, but due to interface effects related to the Fe{sub 70}Cu{sub 30} interlayer. Combined with control experiments using Pt/Fe{sub 70}Cu{sub 30} devices, we conclude that the enhancement of the LSSE voltage in the Pt/Fe{sub 70}Cu{sub 30}/BiYIG devices is attributedmore » to the improvement of the spin-mixing conductance at the Pt/BiYIG interfaces.« less

Characterization of iron, manganese, and copper synthetic hydroxyapatites by electron paramagnetic resonance spectroscopy

NASA Technical Reports Server (NTRS)

Sutter, B.; Wasowicz, T.; Howard, T.; Hossner, L. R.; Ming, D. W.

2002-01-01

The incorporation of micronutrients (e.g., Fe, Mn, Cu) into synthetic hydroxyapatite (SHA) is proposed for slow release of these nutrients to crops in NASA's Advanced Life Support (ALS) program for long-duration space missions. Separate Fe3+ (Fe-SHA), Mn2+ (Mn-SHA), and Cu2+ (Cu-SHA) containing SHA materials were synthesized by a precipitation method. Electron paramagnetic resonance (EPR) spectroscopy was used to determine the location of Fe3+, Mn2+, and Cu2+ ions in the SHA structure and to identify other Fe(3+)-, Mn(2+)-, and Cu(2+)-containing phases that formed during precipitation. The EPR parameters for Fe3+ (g=4.20 and 8.93) and for Mn2+ (g=2.01, A=9.4 mT, D=39.0 mT and E=10.5 mT) indicated that Fe3+ and Mn2+ possessed rhombic ion crystal fields within the SHA structure. The Cu2+ EPR parameters (g(z)=2.488, A(z)=5.2 mT) indicated that Cu2+ was coordinated to more than six oxygens. The rhombic environments of Fe3+ and Mn2+ along with the unique Cu2+ environment suggested that these metals substituted for the 7 or 9 coordinate Ca2+ in SHA. The EPR analyses also detected poorly crystalline metal oxyhydroxides or metal-phosphates associated with SHA. The Fe-, Mn-, and Cu-SHA materials are potential slow release sources of Fe, Mn, and Cu for ALS and terrestrial cropping systems.

Coagulation-flocculation as pre-treatment for micro-scale Fe/Cu/O3 process (CF-mFe/Cu/O3) treatment of the coating wastewater from automobile manufacturing.

PubMed

Xiong, Zhaokun; Cao, Jinyan; Yang, Dan; Lai, Bo; Yang, Ping

2017-01-01

A coagulation-flocculation as pre-treatment combined with mFe/Cu/O 3 (CF-mFe/Cu/O 3 ) process was developed to degrade the pollutants in automobile coating wastewater (ACW). In coagulation-flocculation (CF) process, high turbidity removal efficiency (97.1%) and low COD removal efficiency (10.5%) were obtained under the optimal conditions using Al 2 (SO 4 ) 3 ·18H 2 O and CaO. The effluent of CF process (ECF) was further disposed by mFe/Cu/O 3 process, and its key operating parameters were optimized by batch experiments. Optimally, COD removal efficiency of ECF obtained by the mFe/Cu/O 3 process (i.e., 87.6% after 30 min treatment) was much higher than those of mFe/Cu alone (8.3%), ozone alone (46.6%), and mFe/Cu/air (6.1%), which confirms the superiority of the mFe/Cu/O 3 process. In addition, the analysis results of UV-vis, excitation-emission matrix (EEM) fluorescence spectra and GC/MS further confirm that the phenol pollutants of ECF had been effectively decomposed or transformed after CF-mFe/Cu/O 3 process treatment. Meanwhile, B/C ratio of ACW increased from 0.19 to 0.56, which suggests the biodegradability was improved significantly. Finally, the operating cost of CF-mFe/Cu/O 3 process was about 1.83 USD t -1 for ACW treatment. Therefore, the combined process is a promising treatment technology for the coating wastewater from automobile manufacturing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis of mesoporous triple-metal nanosorbent from layered double hydroxide as an efficient new sorbent for removal of dye from water and wastewater.

PubMed

Kostić, Miloš; Radović, Miljana; Velinov, Nena; Najdanović, Slobodan; Bojić, Danijela; Hurt, Andrew; Bojić, Aleksandar

2018-09-15

In this study, co-precipitation synthesis of the mesoporous triple-metal nanosorbent from Fe, Cu, Ni layered double hydroxide (FeCuNi-LDH), on the basis of the data obtained from the TG analysis was carried out. The FTIR spectroscopy and XRD results confirm the formation of CuO, NiO and Fe 2 O 3 nanoparticles, while the EDX analysis does not show significant variations on the surface in elemental composition. BET analysis shows that FeCuNi-280 (FeCuNi-LDH calcinated at 280 °C) with mesoporous structure, has larger surface area compared to FeCuNi-LDH and FeCuNi-550 (FeCuNi-LDH calcinated at 550 °C). The value of pH PZC of FeCuNi-280 is found to be 8.66. Obtained FeCuNi-280 material showed the ability for efficient removal of dye Reactive Blue 19 (RB19) from water, with a very high sorption capacity of 480.79 mg/g at optimal conditions: the sorbent dose of 0.6 g/dm 3 , stirring speed of 280 rpm and pH 2. The kinetics results of the sorption process were well fitted by pseudo-second order and Chrastil model, and the sorption isotherm was well described by Sips, Langmuir and Brouers-Sotolongo model. FeCuNi-280 was easily regenerated with aqueous solution of NaOH, and reutilization was successfully done in five sorption cycles. The present study show that easy-to-prepare, relatively inexpensive nanosorbent FeCuNi-280 is among the best sorbents for the removal of RB19 dye from water solution and wastewater from textile industry in wide range of pH. Copyright © 2018 Elsevier Inc. All rights reserved.

The role of copper and oxalate in the redox cycling of iron in atmospheric waters

NASA Astrophysics Data System (ADS)

Sedlak, David L.; Hoigné, Jürg

During daytime, the redox cycling of dissolved iron compounds in atmospheric waters, and the related in-cloud transformations of photooxidants, are affected by reactions of Fe and Cu with hydroperoxy (HO 2) and superoxide (O 2-) radicals and the photoreduction of Fe(III)-oxalato complexes. We have investigated several of the important chemical reactions in this redox cycle, through laboratory simulation of the system, using γ-radiation to produce HO 2/O 2-. At concentrations comparable to those measured in atmospheric waters, the redox cycling of Fe was dramatically affected by the presence of oxalate and trace concentrations of Cu. At concentrations more than a hundred times lower than Fe, Cu consumed most of the HO 2/O 2-, and cycled between the Cu(II) and Cu(I) forms. Cu + reacted with FeOH 2+ to produce Fe(II) and Cu(II), with a second order rate constant of approximately 3 × 10 7 M -1s -1. The presence of oxalate resulted in the formation of Fe(III)-oxalato complexes that were essentially unreactive with HO 2/O 2-. Only at high oxalate concentrations was the Fe(II)C 2O 4 complex also formed, and it reacted relatively rapidly with hydrogen peroxide ( k = (3.1 ± 0.6) × 10 4 M -1s -1). Simulations incorporating measurements for other redox mechanisms, including oxidation by ozone, indicate that, during daytime, Fe should be found mostly in the ferrous oxidation state, and that reactions of FeOH 2+ with Cu(I) and HO 2/O 2-, and to a lesser degree, the photolysis of Fe(III)-oxalato complexes, are important mechanisms of Fe reduction in atmospheric waters. The catalytic effect of Cu(II)/Cu(I) and Fe(III)/Fe(II) should also significantly increase the sink function of the atmospheric liquid phase for HO 2 present in a cloud. A simple kinetic model for the reactions of Fe, Cu and HO 2/O 2-, accurately predicted the changes in Fe oxidation states that occurred when authentic fogwater samples were exposed to HO 2/O 2-.

Isotopic Evidence of Unaccounted for Fe and Cu Erythropoietic Pathways

NASA Astrophysics Data System (ADS)

Albarede, F.; Telouk, P.; Lamboux, A.; Jaouen, K.; Balter, V.

2011-12-01

Despite its potential importance for understanding perturbations in the Fe-Cu homeostatic pathways, the natural isotopic variability of these metals in the human body remains unexplored. We measured the Fe, Cu, and Zn isotope compositions of total blood, serum, and red blood cells of ~50 young blood donors by multiple-collector ICP-MS after separation and purification by anion exchange chromatography. Zn is on average 0.2 permil heavier in erythrocytes (δ 66Zn=0.44±0.33 permil) with respect to serum but shows much less overall isotopic variability than Fe and Cu, which indicates that isotope fractionation depends more on redox conditions than on ligand coordination. On average, Fe in erythrocytes (δ 56Fe=-2.59±0.47 permil) is isotopically light by 1-2 permil with respect to serum, whereas Cu in erythrocytes (δ 65Cu=0.56±0.50 permil) is 0.8 percent heavier. Fe and Cu isotope compositions clearly separate erythrocytes of men and women. Fe and Cu from B-type men erythrocytes are visibly more fractionated than all the other blood types. Isotope compositions provide an original method for evaluating metal mass balance and homeostasis. Natural isotope variability shows that the current models of Fe and Cu erythropoiesis, which assume that erythropoiesis is restricted to bone marrow, violate mass balance requirements. It unveils unsuspected major pathways for Fe, with erythropoietic production of isotopically heavy ferritin and hemosiderin, and for Cu, with isotopically light Cu being largely channeled into blood and lymphatic circulation rather than into superoxide dismutase-laden erythrocytes. Iron isotopes provide an intrinsic measuring rod of the erythropoietic yield, while Cu isotopes seem to gauge the relative activity of erythropoiesis and lymphatics.

Fabrication of mesoporous iron (Fe) doped copper sulfide (CuS) nanocomposite in the presence of a cationic surfactant via mild hydrothermal method for supercapacitors

NASA Astrophysics Data System (ADS)

Brown, J. William; Ramesh, P. S.; Geetha, D.

2018-02-01

We report fabrication of mesoporous Fe doped CuS nanocomposites with uniform mesoporous spherical structures via a mild hydrothermal method employing copper nitrate trihydrate (Cu (NO3).3H2O), Thiourea (Tu,Sc(NH2)2 and Iron tri nitrate (Fe(No3)3) as initial materials with cationic surfactant cetyltrimethylamoniame bromide (CTAB) as stabilizer/size controller and Ethylene glycol as solvent at 130 °C temperature. The products were characterized by XRD, SEM/EDX, TEM, FTIR and UV analysis. X-ray diffraction (XRD) spectra confirmed the Fe doped CuS nanocomposites which are crystalline in nature. EDX and XRD pattern confirmed that the product is hexagonal CuS phase. Fe doped spherical structure of CuS with grain size of 21 nm was confirmed by XRD pattern. Fe doping was identified by energy dispersive spectrometry (EDS). The Fourier-transform infrared (FTIR) spectroscopy results revealed the occurrence of active functional groups required for the reduction of copper ions. Studies showed that after a definite time relining on the chosen copper source, the obtained Fe-CuS nanocomposite shows a tendency towards self-assembly and creating mesoporous like nano and submicro structures by TEM/SAED. The achievable mechanism of producing this nanocomposite was primarily discussed. The electrochemical study confirms the pseudocapacitive nature of the CuS and Fe-CuS electrodes. The CuS and Fe-CuS electrode shows a specific capacitance of about 328.26 and 516.39 Fg-1 at a scan rate of 5 mVs-1. As the electrode in a supercapacitor, the mesoporous nanostructured Fe-CuS shows excellent capacitance characteristics.

Local structure study of (In{sub 0.95−x}Fe{sub x}Cu{sub 0.05}){sub 2}O{sub 3} thin films using x-ray absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Yuan; Xing, Yaya; Ma, Guanxiong

2015-07-15

The (In{sub 0.95−x}Fe{sub x}Cu{sub 0.05}){sub 2}O{sub 3} (x = 0.06, 0.08, 0.15, and 0.20) films prepared by RF-magnetron sputtering were investigated by the combination of x-ray absorption spectroscopy (XAS) at Fe, Cu, and O K-edge. Although the Fe and O K-edge XAS spectra show that the Fe atoms substitute for the In sites of In{sub 2}O{sub 3} lattice for all the films, the Cu K-edge XAS spectra reveal that the codoped Cu atoms are separated to form the Cu metal clusters. After being annealed in air, the Fe atoms are still substitutionally incorporated into the In{sub 2}O{sub 3} lattice, while the Cumore » atoms form the CuO secondary phases. With the increase of Fe concentration, the bond length R{sub Fe-O} shortens and the Debye–Waller factor σ{sup 2}{sub Fe-O} increases in the first coordination shell of Fe, which are attributed to the relaxation of oxygen environment around the substitutional Fe ions. The forming of Cu relating secondary phases in the films is due to high ionization energy of Cu atoms, leading that the Cu atoms are energetically much harder to be oxidized to substitute for the In sites of In{sub 2}O{sub 3} lattice than Fe atoms. These results provide new experimental guidance in the preparation of the codoped In{sub 2}O{sub 3} based dilute magnetic oxides.« less

Conditions and mechanisms for the formation of nano-sized Delafossite (CuFeO{sub 2}) at temperatures ≤90 °C in aqueous solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

John, Melanie, E-mail: melanie.john@min.uni-muenchen.de; Heuss-Aßbichler, Soraya; Ullrich, Aladin

In this study, we present the mechanism of CuFeO{sub 2} formation in aqueous solution at low temperatures ≤90 °C, using sulfate salts as reactants. Furthermore, we demonstrate the influence of experimental conditions (alkalization, reaction and ageing temperature and time) on the synthesized nanoparticles. In all cases, GR–SO{sub 4}, a Fe(II–III) layered double hydroxysulphate (Fe{sup 2+}{sub 4}Fe{sup 3+}{sub 2}(OH){sub 12}·SO{sub 4}) and Cu{sub 2}O precipitate first. During further OH{sup −} supply GR–SO{sub 4} oxidizes and forms Fe{sub 10}O{sub 14}(OH){sub 2}, Cu{sub 2}O and CuFeO{sub 2} crystals. Due to the high pH further CuFeO{sub 2} crystals grow at the cost of themore » unstable intermediate products. The reaction rate increases with increasing ageing temperature, reaction pH and, in particular, NaOH concentrations in the solution. As a result, highly crystalline CuFeO{sub 2} (3R and 2H polytypes) nanoparticles showing hexagonal morphology can be synthesized at 70 °C within 10 h or at 50 °C within 1 week. The formation of 2H polytype is favored by additional OH{sup −} supply during the pH-stat time and rather low temperatures. - Highlights: • We solve the formation mechanism of pure CuFeO{sub 2} using sulfates as reactants. • CuFeO{sub 2} nanoparticles crystallize on cost of green rust, Fe{sub 10}O{sub 14}(OH){sub 2} and Cu{sub 2}O. • The reaction rate increases with increasing temperature and OH- concentration. • CuFeO{sub 2} nanoparticles form at 50 °C within one week and at 70 °C within 10 h. • 2H-polytype of CuFeO{sub 2} is favored by additional NaOH supply during pH-stat-time.« less

Mineral composition of commonly consumed ethnic foods in Europe

PubMed Central

Khokhar, Santosh; Garduño-Diaz, Sara D.; Marletta, Luisa; Shahar, Danit R.; Ireland, Jane D.; Jansen-van der Vliet, Martine; de Henauw, Stefaan

2012-01-01

Background Ethnic foods are an integral part of food consumption in Europe contributing towards the overall nutrient intake of the population. Food composition data on these foods are crucial for assessing nutrient intake, providing dietary advice and preventing diseases. Objective To analyse selected minerals in authentic and modified ethnic foods commonly consumed in seven EU member states and Israel. Design A list of ethnic foods commonly consumed in selected European countries was generated, primary samples collected and composite sample prepared for each food, which were analysed for dietary minerals at accredited laboratories. Methods for sampling, analysis, data scrutiny and documentation were based on harmonised procedures. Results New data on 128 ethnic foods were generated for inclusion in the national databases of seven EU countries and Israel within the European Food Information Resource (EuroFIR), an EU Network of Excellence. The Na, K, Ca, P, Mg, Mn, Cl, Fe, Cu, Zn, Se and I contents of 39 foods is presented for the first time in this study. Conclusion The data will serve as an important tool in future national and international food consumption surveys, to target provision of dietary advice, facilitate implementation of policies and inform policymakers, health workers, food industry and researchers. PMID:22768018

Immobilization of Eu and Ho from synthetic acid mine drainage by precipitation with Fe and Al (hydr)oxides.

PubMed

Barcelos, Gisely S; Veloso, Renato Welmer; de Mello, Jaime W V; Gasparon, Massimo

2018-04-30

Use of lime to mitigate acid mine drainage is, in general, accompanied by precipitation of iron (Fe) and aluminium (Al) (hydr)oxides which may increase the removal of trace elements from water. This work aimed to evaluate the precipitation of Fe/Al (hydr)oxides to remove rare earth elements (REE) from contaminated water and the stability of precipitates. Two sets of 60-day syntheses were carried out using different Fe/Al/REE molar ratios, for europium (Eu) and holmium (Ho). The pH was periodically adjusted to 9.0, and the stability of the resulting precipitates was evaluated by water-soluble and BCR extractable phases, namely (1) acid soluble, extracted by 0.11 mol L -1 acetic acid; (2) reducible, extracted with 0.5 mol L -1 hydroxylamine hydrochloride; and (3) oxidisable, extracted with 8.8 mol L -1 hydrogen peroxide efficiencies of the water treatments for both Eu and Ho that were higher than 99.9% irrespective to the Fe/Al/REE molar ratios. Water-soluble phases of Eu and Ho were lower than 0.01% of the total contents in the precipitates. Recoveries from precipitates by Bureau Communautaire de Référence (BCR) sequential extractions increased with increasing concentrations of Eu and Ho. Acetic acid extracted higher amounts of REE, but Eu recovery was superior to Ho. Lepidocrocite was formed as Eu concentration increased which decreased its stability in the precipitates.

An -OH group functionalized MOF for ratiometric Fe3+ sensing

NASA Astrophysics Data System (ADS)

Xu, Hui; Dong, Yingying; Wu, Yuhang; Ren, Wenjing; Zhao, Tao; Wang, Shunli; Gao, Junkuo

2018-02-01

Iron is one of the most important elements in the biochemical processes in all living system, both deficiency or excess of iron will lead to metabolism disorder diseases. However, Fe3+ is one of the most efficient fluorescence quenchers among the transition-metal ions because of its paramagnetic nature. The realization of Fe3+ ratiometric and self-calibrated fluorescent sensor is highly-challenging. We synthesized a novel luminescent -OH functionalized EuOHBDC (Eu2(OH-BDC)3, OH-BDC=2-hydroxyterephthalic acid) by hydrothermal reaction and in situ ligand synthesis, and used it as a rare ratiomatric luminescent sensor for Fe3+ ions. The -OH functional group facilitates both electron transfer and binding interaction between EuOHBDC and Fe3+, which lead to luminescent quenching of ligand-based emission while enhancement of a new peak emission, and thus enables ratiometric detection of Fe3+. The relative fluorescent intensity ratio (I375/I427) increased linearly with increasing Fe3+ concentration in the 10-50 μM range with 1.17 μM (65 ppb) detection limit. The EuOHBDC also shows excellent selectivity towards different metal ions, particularly can discriminate Fe3+ and Fe2+ through different luminescent responses. This result clearly demonstrates the superiority of -OH functionalized MOF for Fe3+ detection, which can contribute to develop high performance luminescent probe for detection of metal ions in environmental and biomedical applications.

A Hybrid Mineral Battery: Energy Storage and Dissolution Behavior of CuFeS2 in a Fixed Bed Flow Cell.

PubMed

Deen, Kashif Mairaj; Asselin, Edouard

2018-05-09

The development of a hybrid system capable of storing energy and the additional benefit of Cu extraction is discussed in this work. A fixed bed flow cell (FBFC) was used in which a composite negative electrode containing CuFeS 2 (80 wt %) and carbon black (20 wt %) in graphite felt was separated from a positive (graphite felt) electrode by a proton-exchange membrane. The anolyte (0.2 m H 2 SO 4 ) and catholyte (0.5 m Fe 2+ in 0.2 m H 2 SO 4 with or without 0.1 m Cu 2+ ) were circulated in the cell. The electrochemical activity of the Fe 2+ /Fe 3+ redox couple over graphite felt significantly improved after the addition of Cu 2+ in the catholyte. Ultimately, in the CuFeS 2 ∥Fe 2+ /Cu 2+ (CFeCu) FBFC system, the specific capacity increased continuously to 26.4 mAh g -1 in 500 galvanostatic charge-discharge (GCD) cycles, compared to the CuFeS 2 ∥Fe 2+ (CFe) system (13.9 mAh g -1 ). Interestingly, the specific discharge energy gradually increased to 3.6 Wh kg -1 in 500 GCD cycles for the CFeCu system compared to 3.29 Wh kg -1 for the CFe system in 150 cycles. In addition to energy storage, 10.75 % Cu was also extracted from the mineral, which is an important feature of the CFeCu system as it would allow Cu extraction and recovery through hydrometallurgical methods. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of spin entropy and lattice strain from mixed-trivalent Fe3+/Cr3+ on the electronic, thermoelectric and optical properties of delafossite CuFe1-x Cr x O2 (x  =  0.25, 0.5, 0.75)

NASA Astrophysics Data System (ADS)

Ruttanapun, Chesta; Maensiri, Santi

2015-12-01

Mixed-trivalent Fe3+/Cr3+ content CuFe1-x Cr x O2 (x  =  0.25, 0.5, and 0.75) compounds were synthesized to investigate the effects of spin entropy, and lattice strain on their electronic, thermoelectric and optical properties. The XPS results showed the existence of mixed Cu1+/Cu2+, Fe3+/Fe4+ and Cr2+/Cr3+ ion states in the structures. The mixed Fe3+/Cr3+ions caused a strong correlation to occur between the spin and the orbitals of the carriers in the octahedral layer of the sample, affecting the carrier degeneracy Seebeck coefficient behaviour, and the Cu2+ and Fe4+ ions caused an effect of enhancing the electric conductivity. These effects meant that CuFe0.75Cr0.25O2 had the highest electrical conductivity, an enhanced Seebeck coefficient compared to that of CuFeO2-based compounds, and the highest thermopower value. The lowest thermal conductivity was that of CuFe0.5Cr0.5O2, which was a result of the mismatched atomic radii of the mixed trivalent Fe3+(0.645 Å)/Cr3+(0.615 Å), which caused the lattice strain to occur in the structure and thus affected the point defect scattering of the phonon thermal conductivity. The lowest total thermal conductivity was that of CuFe0.5Cr0.5O2, because it had the maximum lattice strain. Overall, the effect of the mixed trivalent elements caused CuFe0.75Cr0.25O2 to have the highest value of the dimensionless figure of merit ZT, with a value that was four times that of CuFeO2-based compounds and six times that of CuCrO2-based compounds. With regard to optical properties, the lattice strain causes the indirect optical gap to increase with increasing x content, but has no effect on the direct optical gap. These results verified that the mixed-trivalent Fe3+/Cr3+ content of CuFe1-x Cr x O2 (x  =  0.25, 0.5, and 0.75) affected the electronic, thermoelectric and optical properties of the structure by causing spin entropy and lattice strain to occur.

A microscopic solution to the magnetic detwinning mystery in EuFe2As2

NASA Astrophysics Data System (ADS)

Maiwald, J.; Mazin, I. I.; Nandi, S.; Xiao, Y.; Gegenwart, P.

One of the greatest recent advances in studying nematic phenomena in Fe-based superconductors was the mechanical detwinning of the 122-family compounds. Unfortunately, these techniques generate considerable stress in the investigated samples, which contaminates the results. Recently, we observed that a minuscule magnetic field of the order of 0.1 T irreversibly and persistently detwins EuFe2As2, opening an entirely new avenue for addressing nematicity. However, further development was hindered by the absence of a microscopic theory explaining this magnetic detwinning. In fact, Eu2+ has zero orbital moment and does not couple to the lattice, and its exchange coupling with the Fe sublattice cancels by symmetry. Moreover, further increase of the field to 1 T leads to a reorientation of Fe domains, while even larger fields 10 T reorient the domains once again. We will present a new microscopic model, based on a sizable biquadratic coupling between the Fe 3 d and Eu 4 f moments. This model quantitatively explains our old and new magnetization and neutron diffraction data, thus removing the veil of mystery and finally opening the door to full-scale research into magnetic detwinning and nematicity in Fe-based superconductors.

Beneficial Role of Copper in the Enhancement of Durability of Ordered Intermetallic PtFeCu Catalyst for Electrocatalytic Oxygen Reduction.

PubMed

Arumugam, Balamurugan; Tamaki, Takanori; Yamaguchi, Takeo

2015-08-05

Design of Pt alloy catalysts with enhanced activity and durability is a key challenge for polymer electrolyte membrane fuel cells. In the present work, we compare the durability of the ordered intermetallic face-centered tetragonal (fct) PtFeCu catalyst for the oxygen reduction reaction (ORR) relative to its counterpart bimetallic catalysts, i.e., the ordered intermetallic fct-PtFe catalyst and the commercial catalyst from Tanaka Kikinzoku Kogyo, TKK-PtC. Although both fct catalysts initially exhibited an ordered structure and mass activity approximately 2.5 times higher than that of TKK-Pt/C, the presence of Cu at the ordered intermetallic fct-PtFeCu catalyst led to a significant enhancement in durability compared to that of the ordered intermetallic fct-PtFe catalyst. The ordered intermetallic fct-PtFeCu catalyst retained more than 70% of its mass activity and electrochemically active surface area (ECSA) over 10 000 durability cycles carried out at 60 °C. In contrast, the ordered intermetallic fct-PtFe catalyst maintained only about 40% of its activity. The temperature of the durability experiment is also shown to be important: the catalyst was more severely degraded at 60 °C than at room temperature. To obtain insight into the observed enhancement in durability of fct-PtFeCu catalyst, a postmortem analysis of the ordered intermetallic fct-PtFeCu catalyst was carried out using scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDX) line scan. The STEM-EDX line scans of the ordered intermetallic fct-PtFeCu catalyst over 10 000 durability cycles showed a smaller degree of Fe and Cu dissolution from the catalyst. Conversely, large dissolution of Fe was identified in the ordered intermetallic fct-PtFe catalyst, indicating a lesser retention of Fe that causes the destruction of ordered structure and gives rise to poor durability. The enhancement in the durability of the ordered intermetallic fct-PtFeCu catalyst is ascribed to the synergistic effects of Cu presence and the ordered structure of catalyst.

Influences on Distribution of Solute Atoms in Cu-8Fe Alloy Solidification Process Under Rotating Magnetic Field

NASA Astrophysics Data System (ADS)

Zou, Jin; Zhai, Qi-Jie; Liu, Fang-Yu; Liu, Ke-Ming; Lu, De-Ping

2018-05-01

A rotating magnetic field (RMF) was applied in the solidification process of Cu-8Fe alloy. Focus on the mechanism of RMF on the solid solution Fe(Cu) atoms in Cu-8Fe alloy, the influences of RMF on solidification structure, solute distribution, and material properties were discussed. Results show that the solidification behavior of Cu-Fe alloy have influenced through the change of temperature and solute fields in the presence of an applied RMF. The Fe dendrites were refined and transformed to rosettes or spherical grains under forced convection. The solute distribution in Cu-rich phase and Fe-rich phase were changed because of the variation of the supercooling degree and the solidification rate. Further, the variation in solute distribution was impacted the strengthening mechanism and conductive mechanism of the material.

Growth-induced anisotropy in bismuth - Rare-earth iron garnets

NASA Technical Reports Server (NTRS)

Fratello, V. J.; Slusky, S. E. G.; Brandle, C. D.; Norelli, M. P.

1986-01-01

The bismuth-doped rare-earth iron garnets, (R3-x-yBixPby)Fe5O12 (Bi:RIG, R = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), were prepared under constant growth conditions to investigate the influence of ionic species on the bismuth-based growth-induced uniaxial anisotropy K(u) exp g. The effect of ionic species on growth-induced anisotropy in Bi:RIG was not consistent with the ionic size model of site ordering. In particular, Bi:SmIG, Bi:EuIG, and Bi:TbIG displayed high growth-induced anisotropies, up to 331,000 erg/cu cm at room temperature for x of about 0.5. The temperature dependence of these K(u) exp gs was somewhat higher than that of the well studied Bi:YIG. The site ordering of Bi can be modeled by assuming that small, low-oxygen-coordination BiOw exp +3-2 w melt complexes have a strong site selectivity for small, high-oxygen coordination sites at the growth interface.

Systematic investigation of structural and morphological studies on doped TiO2 nanoparticles for solar cell applications

NASA Astrophysics Data System (ADS)

Murugadoss, G.; Jayavel, R.; Rajesh Kumar, M.

2014-12-01

Optical, structural and thermal properties of the doped with different ions (transition metals, other metals or post transition metals, non-metals, alkali metals and lanthanides) in TiO2 nanocrystals were investigated. The doped nanoparticles were synthesized by modified chemical method. Ethanol-deionised water mixer (20:1) was used as solvent for synthesize of the undoped and doped TiO2 nanoparticles. Systematic studies on structural and morphological changes by thermal treatment on TiO2 were examined. It has been observed that with Eu and Al doping TiO2, the phase transition temperature for anatase to rutile phase increased. Blue and red shifting absorptions were observed for doped TiO2 in visible region. Among the dopant, significant blue shift was obtained for Cu, Cd, Ag, Y, Ce and In doped TiO2 and red shift was obtained for Zr, Sm, Al, Na, S, Fe, Ni, Eu and Gd doped TiO2 nanoparticles.

Studies of Positrons Trapped at Quantum-Dot Like Particles Embedded in Metal Surfaces

NASA Astrophysics Data System (ADS)

Fazleev, N. G.; Nadesalingam, M. P.; Weiss, A. H.

2009-03-01

Experimental studies of the positron annihilation induced Auger electron (PAES) spectra from the Fe-Cu alloy surfaces with quantum-dot like Cu nanoparticles embedded in Fe show that the PAES signal from Cu increase rapidly as the concentration of Cu is enhanced by vacuum annealing. These measurements indicate that almost 75% of positrons that annihilate with core electrons due so with Cu even though the surface concentration of Cu as measured by EAES is only 6%. This result suggests that positrons become localized at sites at the surface containing high concentration of Cu atoms before annihilation. These experimental results are investigated theoretically by performing calculations of the "image-potential" positron surface states and annihilation characteristics of the surface trapped positrons with relevant Fe and Cu core-level electrons for the clean Fe(100) and Cu(100) surfaces and for the Fe(100) surface with quantum-dot like Cu nanoparticles embedded in the top atomic layers of the host substrate. Estimates of the positron binding energy and positron annihilation characteristics reveal their strong sensitivity to the nanoparticle coverage. Computed core annihilation probabilities are compared with experimental ones estimated from the measured Auger peak intensities. The observed behavior of the Fe and Cu PAES signal intensities is explained by theoretical calculations as being due to trapping of positrons in the regions of Cu nanoparticles embedded in the top atomic layers of Fe.

Synthesis of Cu-Fe{sub 3}O{sub 4}@graphene composite: A magnetically separable and efficient catalyst for the reduction of 4-nitrophenol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Ran; Bi, Huiping, E-mail: hpbi@njust.edu.cn; He, Guangyu

2014-09-15

Highlights: • The Cu-Fe{sub 3}O{sub 4}@GE composite was prepared by one-step solvent–thermal method. • The Cu-Fe{sub 3}O{sub 4}@GE composite exhibited the highest catalytic activity with excellent stability. • The Cu-Fe{sub 3}O{sub 4}@GE composite was magnetically separable. - Abstract: In this work, the Cu-Fe{sub 3}O{sub 4}@GE composite was prepared easily by a one-step solvent–thermal method, which achieved the formation of Cu nanoparticles (Cu NPs), Fe{sub 3}O{sub 4} nanoparticles (Fe{sub 3}O{sub 4} NPs) and reduction of GO simultaneously. The morphology and structure of the composite was fully characterized by means of X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, transmission electron microscopymore » (TEM). The time-dependent adsorption spectra of the reaction mixture was measured by UV–vis absorption spectroscopy. The results demonstrated that the Cu NPs and Fe{sub 3}O{sub 4} NPs were densely and evenly deposited on the graphene (GE) sheets. It was found that the Cu-Fe{sub 3}O{sub 4}@GE composite exhibited high catalytic activities on the reduction of p-nitrophenol to p-aminophenol. Furthermore, the composite catalyst can be easily recovered due to its magnetic separability and high stability.« less

Phase equilibria in the nominally Al65Cu23Fe12 system at 3, 5 and 21 GPa: Implications for the quasicrystal-bearing Khatyrka meteorite

NASA Astrophysics Data System (ADS)

Stagno, Vincenzo; Bindi, Luca; Steinhardt, Paul J.; Fei, Yingwei

2017-10-01

Two of the three natural quasiperiodic crystals found in the Khatyrka meteorite show a composition within the Al-Cu-Fe system. Icosahedrite, with formula Al63Cu24Fe13, coexists with the new Al62Cu31Fe7 quasicrystal plus additional Al-metallic minerals such as stolperite (AlCu), kryachkoite [(Al,Cu)6(Fe,Cu)], hollisterite (AlFe3), khatyrkite (Al2Cu) and cupalite (AlCu), associated to high-pressure phases like ringwoodite/ahrensite, coesite, and stishovite. These high-pressure minerals represent the evidence that most of the Khatyrka meteoritic fragments formed at least at 5 GPa and 1200 °C, if not at more extreme conditions. On the other hand, experimental studies on phase equilibria within the representative Al-Cu-Fe system appear mostly limited to ambient pressure conditions, yet. This makes the interpretation of the coexisting mineral phases in the meteoritic sample quite difficult. We performed experiments at 3, 5 and 21 GPa and temperatures of 800-1500 °C using the multi-anvil apparatus to investigate the phase equilibria in the Al65Cu23Fe12 system representative of the first natural quasicrystal, icosahedrite. Our results, supported by single-crystal X-ray diffraction and analyses by scanning electron microscopy, confirm the stability of icosahedrite at high pressure and temperature along with additional coexisting Al-bearing phases representative of khatyrkite and stolperite as those found in the natural meteorite. One reversal experiment performed at 5 GPa and 1200 °C shows the formation of the icosahedral quasicrystal from a pure Al, Cu and Fe mixture, a first experimental synthesis of icosahedrite under those conditions. Pressure appears to not play a major role in the distribution of Al, Cu and Fe between the coexisting phases, icosahedrite in particular. Results from this study extend our knowledge on the stability of icosahedral AlCuFe at higher temperature and pressure than previously examined, and provide a new constraint on the stability of icosahedrite.

A GREEN CHEMISTRY APPROACH TO PREPARATION OF CORE (FE OR CU)-SHELL (NOBLE METALS) NANOCOMPOSITES USING AQUEOUS ASCORBIC ACID

EPA Science Inventory

A greener method to fabricate novel core (Fe or Cu)-shell (noble metals) nanocomposites of transition metals such as Fe and Cu and noble metals such as Au, Pt, Pd, and Ag using aqueous ascorbic acid is described. Transition metal salts such as Cu and Fe were reduced using ascor...

Fluorescent and colorimetric detection of Fe(III) and Cu(II) by a difunctional rhodamine-based probe

NASA Astrophysics Data System (ADS)

Wang, Lei; Ye, Dandan; Li, Wenxuan; Liu, Yuanyuan; Li, Longhua; Zhang, Wenli; Ni, Liang

2017-08-01

A new rhodamine B hydrazone derivative (probe L) was synthesized and characterized. The probe L had sufficiently satisfactory selective response to Fe3 + and Cu2 + ions among various interferential metal ions, and high sensitivity with the detection limit of 4.63 × 10- 9 M and 5.264 × 10- 7 M for Fe3 + and Cu2 + ions, respectively. In the presence of Fe3 +, the probe L exhibited turn-on orange fluorescence accompanied by color change from colorless to pink. Toward Cu2 +, the probe L showed significant color change from colorless to red purple. These remarkable orange fluorescence and color change made probe L suitable naked-eye identify for Fe3 + and Cu2 + ions. By means of Job's plot, Benesi-Hildebrand studies and FTIR spectra, both 1:1 binding modes (L-Fe3 + and L-Cu2 +) were confirmed. The coordination mechanism and turn on/off fluorescence for L-Fe3 + and L-Cu2 + complexes were well explained by theoretical calculations. Moreover, probe L could be used as a quick, simple, visual test strip for Fe3 + and Cu2 + detection.

Copper tolerance in Frankia sp. strain EuI1c involves surface binding and copper transport.

PubMed

Rehan, Medhat; Furnholm, Teal; Finethy, Ryan H; Chu, Feixia; El-Fadly, Gomaah; Tisa, Louis S

2014-09-01

Several Frankia strains have been shown to be copper-tolerant. The mechanism of their copper tolerance was investigated for Frankia sp. strain EuI1c. Copper binding was shown by binding studies. Unusual globular structures were observed on the surface of the bacterium. These globular structures were composed of aggregates containing many relatively smaller "leaf-like" structures. Scanning electron microscopy with energy-dispersive X-ray (SEM-EDAX) analysis of these structures indicated elevated copper and phosphate levels compared to the control cells. Fourier transform infrared spectroscopy (FTIR) analysis indicated an increase in extracellular phosphate on the cell surface of copper-stressed cells. Bioinformatics' analysis of the Frankia sp. strain EuI1c genome revealed five potential cop genes: copA, copZ, copC, copCD, and copD. Experiments with Frankia sp. strain EuI1c using qRT-PCR indicated an increase in messenger RNA (mRNA) levels of the five cop genes upon Cu(2+) stress. After 5 days of Cu(2+) stress, the copA, copZ, copC, copCD, and copD mRNA levels increased 25-, 8-, 18-, 18-, and 25-fold, respectively. The protein profile of Cu(2+)-stressed Frankia sp. strain EuI1c cells revealed the upregulation of a 36.7 kDa protein that was identified as FraEuI1c_1092 (sulfate-binding periplasmic transport protein). Homologues of this gene were only present in the genomes of the Cu(2+)-resistant Frankia strains (EuI1c, DC12, and CN3). These data indicate that copper tolerance by Frankia sp. strain EuI1c involved the binding of copper to the cell surface and transport proteins.

Structural, morphological and magnetic properties of Eu-doped CoFe2O4 nano-ferrites

NASA Astrophysics Data System (ADS)

Zubair, Aiman; Ahmad, Zahoor; Mahmood, Azhar; Cheong, Weng-Chon; Ali, Irshad; Khan, Muhammad Azhar; Chughtai, Adeel Hussain; Ashiq, Muhammad Naeem

Europium (Eu) doped spinel cobalt ferrites having composition CoEuxFe2-xO4 where x = 0.00, 0.03, 0.06, 0.09, 0.12 were fabricated by co-precipitation route. In order to observe the phase development of the ferrite samples, thermo-gravimetric analysis was carried out. The synthesized samples were subjected to X-ray diffraction analysis for structural investigation. All the samples were found to constitute face centered cubic (FCC) spinel structure belonging to Fd3m space group. Scanning electron microscopy revealed the formation of nanocrystalline grains with spherical shape. Energy dispersive X-ray spectra confirmed the presence of Co, Eu, Fe and O elements with no existence of any impurity. The magnetic hysteresis curves measured at room temperature exhibited ferrimagnetic behavior with maximum saturation magnetization (Ms) of 65 emu/g and coercivity (Hc) of 966 Oe. The origin of ferrimagnetism in Eu doped cobalt ferrites was discussed in detail with reverence to the allocation of Co2+ and Fe3+ ions within the spinel lattice. The overall coercivity was increased (944-966 Oe) and magnetization was decreased (65-46 emu/g) with the substitution of Eu3+. The enhancement of former is ascribed to the transition from multi domain to single domain state and reduction in lateral is attributed to the incorporation of nonmagnetic Eu ions for Fe, resulting in weak superexchange interactions.

Pulsed Laser Deposition Growth of Delafossite (CuFeO2) thin films and multilayers

NASA Astrophysics Data System (ADS)

Joshi, Toyanath; Ferrari, Piero; Borisov, Pavel; Cabrera, Alejandro; Lederman, David

2014-03-01

Owing to its narrow band gap (<2 eV) and p-type conductivity delafossite CuFeO2 is attractive for applications in the field of solar energy conversion. Obtaining pure phase CuFeO2 thin films, however, is relatively difficult. It is necessary to maintain the lowest possible Cu valency (+1) in order to avoid forming the comparably stable spinel compound CuFe2O4. We present a systematic study of the pulsed laser deposition (PLD) growth conditions for epitaxial (00.1) oriented CuFeO2 thin films on Al2O3 (00.1) substrates. The secondary impurity phase, CuFe2O4, was removed completely by optimizing the growth conditions. RHEED, XRD and TEM showed that the pure phase delafossite films are highly epitaxial to the substrate. The chemical purity was verified by Raman and XPS. The indirect bandgap of 1.15 eV was measured using infrared reflectivity, and is in agreement with the CuFeO2 bulk value. Finally, we discuss the growth and structural characterization of delafossite multilayers, CuFeO2/CuGaO2. This work was supported by a Research Challenge Grant from the West Virginia Higher Education Policy Commission (HEPC.dsr.12.29) and the Microelectronics Advanced Research Corporation (Contract # 2013-MA-2382) at WVU.

Theoretical Investigation of Calculating Temperatures in the Combining Zone of Cu/Fe Composite Plate Jointed by Explosive Welding

NASA Astrophysics Data System (ADS)

Qu, Y. D.; Zhang, W. J.; Kong, X. Q.; Zhao, X.

2016-03-01

The heat-transfer behavior of the interface of Flyer plate (or Base Plate) has great influence on the microcosmic structures, stress distributions, and interface distortion of the welded interface of composite plates by explosive welding. In this paper, the temperature distributions in the combing zone are studied for the case of Cu/Fe composite plate jointed by explosive welding near the lower limit of explosive welding. The results show that Flyer plate (Cu plate) and Base Plate (Fe plate) firstly almost have the same melting rate in the explosive welding process. Then, the melting rate of Cu plate becomes higher than that of Fe plate. Finally, the melt thicknesses of Cu plate and Fe plate trend to be different constants, respectively. Meanwhile, the melting layer of Cu plate is thicker than that of Fe plate. The research could supply some theoretical foundations for calculating the temperature distribution and optimizing the explosive welding parameters of Cu/Fe composite plate to some extent.

Fe(II)/Cu(II) interaction on goethite stimulated by an iron-reducing bacteria Aeromonas Hydrophila HS01 under anaerobic conditions.

PubMed

Tao, Liang; Zhu, Zhen-Ke; Li, Fang-Bai; Wang, Shan-Li

2017-11-01

Copper is a trace element essential for living creatures, but copper content in soil should be controlled, as it is toxic. The physical-chemical-biological features of Cu in soil have a significant correlation with the Fe(II)/Cu(II) interaction in soil. Of significant interest to the current study is the effect of Fe(II)/Cu(II) interaction conducted on goethite under anaerobic conditions stimulated by HS01 (a dissimilatory iron reduction (DIR) microbial). The following four treatments were designed: HS01 with α-FeOOH and Cu(II) (T1), HS01 with α-FeOOH (T2), HS01 with Cu(II) (T3), and α-FeOOH with Cu(II) (T4). HS01 presents a negligible impact on copper species transformation (T3), whereas the presence of α-FeOOH significantly enhanced copper aging contributing to the DIR effect (T1). Moreover, the violent reaction between adsorbed Fe(II) and Cu(II) leads to the decreased concentration of the active Fe(II) species (T1), further inhibiting reactions between Fe(II) and iron (hydr)oxides and decelerating the phase transformation of iron (hydr)oxides (T1). From this study, the effects of the Fe(II)/Cu(II) interaction on goethite under anaerobic conditions by HS01 are presented in three aspects: (1) the accelerating effect of copper aging, (2) the reductive transformation of copper, and (3) the inhibition effect of the phase transformation of iron (hydr)oxides. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effets Seebeck et Nernst dans les cuprates: Etude de la reconstruction de la surface de Fermi sous champ magnetique intense

NASA Astrophysics Data System (ADS)

Laliberte, Francis

2010-06-01

Ce memoire presente des mesures de transport thermoelectrique, les effets Seebeck et Nernst, dans une serie d'echantillons de supraconducteurs a haute temperature critique. Des resultats obtenus recemment au Laboratoire National des Champs Magnetiques Intenses a Grenoble sur La1.7Eu0.2Sr0.1 CuO4, La1.675Eu0.2Sr0.125CuO 4, La1.64Eu0.2Sr0.16CuO4, La1.74Eu0.1Sr0.16CuO4 et La 1.4Nd0.4Sr0.2CuO4 sont analyses. Une attention particuliere est accordee aux equations de la theorie semi-classique du transport et leur validite est verifiee. La procedure experimentale et les materiaux utilises pour concevoir les montages de mesures sont expliques en detail. Enfin, un chapitre est dedie a l'explication et l'interpretation des resultats de transport thermoelectrique sur YBa2Cu3O6+delta publies au cours de l'hiver 2010 dans les revues Nature et Physical Review Letters. Les donnees d'effet Seebeck dans les echantillons de La 1.8-x,Eu0.2SrxCuO 4, ou un changement de signe est observe, permettent de conclure a la presence d'une poche d'electrons dans la surface de Fermi qui domine le transport a basse temperature dans la region sous-dopee du diagramme de phase. Cette conclusion est similaire a celle obtenue par des mesures d'effet Hall dans YBa 2Cu3O6+delta et elle cadre bien dans un scenario de reconstruction de la surface de Fermi. Les donnees d'effet Nernst recueillies indiquent que la contribution des fluctuations supraconductrices est limitee a un modeste intervalle de temperature au-dessus de la temperature critique.

Varying Eu2+ magnetic order by chemical pressure in EuFe2(As1-xPx)2

NASA Astrophysics Data System (ADS)

Zapf, S.; Wu, D.; Bogani, L.; Jeevan, H. S.; Gegenwart, P.; Dressel, M.

2011-10-01

Based on low-field magnetization measurements on a series of single crystals, we present a scheme of the Eu2+ spin alignment in EuFe2(As1-xPx)2. We explain observations of the Eu2+ ordering previously reported, reconciling different existing phase diagrams. The magnetic moments of the Eu2+ ions are slightly canted, yielding a ferromagnetic contribution along the c direction that becomes stronger with pressure, until superconductivity sets in. The spin-density wave as well as the superconducting phase coexist with an antiferromagnetic interlayer coupling of the canted spins. Reducing the interlayer distance finally leads to a ferromagnetic Eu2+ interlayer coupling and to the suppression of superconductivity.

Magnetic properties of quadruple perovskite solid solutions Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} and Y{sub 1–y}Ce{sub x}Cu{sub 3}Fe{sub 4}O{sub 12}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murakami, Makoto; Mori, Shigeo; Yamada, Ikuya, E-mail: i-yamada@21c.osakafu-u.ac.jp

Magnetic properties of the quadruple perovskite solid solutions Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} and Y{sub 1–y}Ce{sub y}Cu{sub 3}Fe{sub 4}O{sub 12} are investigated. Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} shows continuous increase in the ferromagnetic transition temperature as x increases. Y{sub 1–y}Ce{sub y}Cu{sub 3}Fe{sub 4}O{sub 12} exhibits a ferromagnetic-antiferromagnetic transition in the vicinity of y = 0.5. These observations demonstrate the electron doping effect on magnetic properties of charge-disproportionated ACu{sub 3}Fe{sub 4}O{sub 12} phases.

Activities in Cu2S-FeS-PbS melts at 1200 °C

NASA Astrophysics Data System (ADS)

Eriç, H.; Timuçin, M.

1981-09-01

The dew-point method was used to determine the vapor pressures of PbS over liquid sulfides of the system Cu2S-FeS-PbS at 1200 °C. From the PbS activity data, activities of Cu2S and FeS were evaluated both in binary and ternary melts by Gibbs-Duhem calculations. The systems Cu2S-PbS and Cu2S-FeS exhibit negative departures from ideal behavior, while the FeS-PbS melts are ideal solutions at 1200 °C.

Rosette iron deficiency transcript and microRNA profiling reveals links between copper and iron homeostasis in Arabidopsis thaliana

PubMed Central

Waters, Brian M.; Stein, Ricardo J.

2012-01-01

Iron (Fe) is an essential plant micronutrient, and its deficiency limits plant growth and development on alkaline soils. Under Fe deficiency, plant responses include up-regulation of genes involved in Fe uptake from the soil. However, little is known about shoot responses to Fe deficiency. Using microarrays to probe gene expression in Kas-1 and Tsu-1 ecotypes of Arabidopsis thaliana, and comparison with existing Col-0 data, revealed conserved rosette gene expression responses to Fe deficiency. Fe-regulated genes included known metal homeostasis-related genes, and a number of genes of unknown function. Several genes responded to Fe deficiency in both roots and rosettes. Fe deficiency led to up-regulation of Cu,Zn superoxide dismutase (SOD) genes CSD1 and CSD2, and down-regulation of FeSOD genes FSD1 and FSD2. Eight microRNAs were found to respond to Fe deficiency. Three of these (miR397a, miR398a, and miR398b/c) are known to regulate transcripts of Cu-containing proteins, and were down-regulated by Fe deficiency, suggesting that they could be involved in plant adaptation to Fe limitation. Indeed, Fe deficiency led to accumulation of Cu in rosettes, prior to any detectable decrease in Fe concentration. ccs1 mutants that lack functional Cu,ZnSOD proteins were prone to greater oxidative stress under Fe deficiency, indicating that increased Cu concentration under Fe limitation has an important role in oxidative stress prevention. The present results show that Cu accumulation, microRNA regulation, and associated differential expression of Fe and CuSOD genes are coordinated responses to Fe limitation. PMID:22962679

The effect of titanite crystallisation on Eu and Ce anomalies in zircon and its implications for the assessment of porphyry Cu deposit fertility

NASA Astrophysics Data System (ADS)

Loader, Matthew A.; Wilkinson, Jamie J.; Armstrong, Robin N.

2017-08-01

The redox sensitivity of Ce and Eu anomalies in zircon has been clearly demonstrated by experimental studies, and these may represent an important tool in the exploration for porphyry Cu deposits which are thought to be derived from oxidised magmas. These deposits are significant because they are the source of much of the world's copper and almost all of the molybdenum and rhenium, key elements in many modern technologies. However, Ce and Eu anomalies in zircon are also affected by the co-crystallisation of REE bearing phases, such as titanite. Here, we report the trace element chemistry of zircons from titanite-bearing intrusions associated with mineralisation at the world class Oyu Tolgoi porphyry Cu-Au deposit (Mongolia). Based on these data, we suggest that neither zircon Eu/Eu*, nor Ce4+/Ce3+ are robust proxies for melt redox conditions, because they are both too strongly dependent on melt REE concentrations, which are usually poorly constrained and controlled by the crystallisation of titanite and other REE-bearing phases. In spite of this, Eu/Eu* can broadly distinguish between fertile and barren systems, so may still be an indicator of porphyry magma fertility, and a useful tool for exploration.

The magnetic structure of EuCu 2Sb 2

DOE PAGES

Ryan, D. H.; Cadogan, J. M.; Anand, V. K.; ...

2015-05-06

Antiferromagnetic ordering of EuCu 2Sb 2 which forms in the tetragonal CaBe 2Ge 2-type structure (space group P4/nmm #129) has been studied using neutron powder diffraction and 151Eu Mössbauer spectroscopy. The room temperature 151Eu isomer shift of –12.8(1) mm/s shows the Eu to be divalent, while the 151Eu hyperfine magnetic field (B hf) reaches 28.7(2) T at 2.1 K, indicating a full Eu 2+ magnetic moment. B hf(T) follows a smoothmore » $$S=\\frac{7}{2}$$ Brillouin function and yields an ordering temperature of 5.1(1) K. Refinement of the neutron diffraction data reveals a collinear A-type antiferromagnetic arrangement with the Eu moments perpendicular to the tetragonal c-axis. As a result, the refined Eu magnetic moment at 0.4 K is 7.08(15) μ B which is the full free-ion moment expected for the Eu 2+ ion with $$S=\\frac{7}{2}$$ and a spectroscopic splitting factor of g = 2.« less

Characterization of Cu buffer layers for growth of L10-FeNi thin films

NASA Astrophysics Data System (ADS)

Mizuguchi, M.; Sekiya, S.; Takanashi, K.

2010-05-01

A Cu(001) layer was fabricated on a Au(001) layer to investigate the use of Cu as a buffer layer for growing L10-FeNi thin films. The epitaxial growth of a Cu buffer layer was observed using reflection high-energy electron diffraction. The flatness of the layer improved drastically with an increase in the substrate temperature although the layer was an alloy (AuCu3). An FeNi thin film was epitaxially grown on the AuCu3 buffer layer by alternate monatomic layer deposition and the formation of an L10-FeNi ordered alloy was expected. The AuCu3 buffer layer is thus a promising candidate material for the growth of L10-FeNi thin films.

The effect of ionic interactions on the oxidation of metals in natural waters

NASA Astrophysics Data System (ADS)

Millero, Frank J.

1985-02-01

The effect of ionic interactions of the major components of natural waters on the oxidation of Cu(I) and Fe(II) has been examined. The various ion pairs of these metals have been shown to have different rates of oxidation. For Fe(II), the chloride and sulfate ion pairs are not easily oxidized. The measured decrease in the rate constant at a fixed pH in chloride and sulfate solutions agrees very well with the values predicted. The effect of pH (6 to 8) on the oxidation of Fe(II) in water and seawater have been shown to follow the rate equation -d in [Fe(II)]/dt = k 1β 1α Fe/[H +] + k 2β 2α Fe/[H +] 2 where k1 and k2 are the pseudo first order rate constants, β1 and β2 are the hydrolysis constants for Fe(OH) + and Fe(OH) 0. The value of αFE is the fraction of free Fe 2+. The value of k1 (2.0 ±0.5 min-1) in water and seawater are similar within experimental error. The value of k2 (1.2 × 10 5 min -1) in seawater is 28% of its value in water in reasonable agreement with predictions using an ion pairing model. For the oxidation of Cu(I) a rate equation of the form -d ln [Cu(I)]/dt = k 0α Cu+ k 1β 1α Cu[Cl] was found where k0 (14.1 sec -1) and k1 (3.9 sec -1) are the pseudo first order rate constants for the oxidation of Cu + and CuCl 0, β1 is the formation constant for CuCl 0 and αCu is the fraction of free Cu +. Thus, unlike the results for Fe(II), Cu(I) chloride complexes have measurable rates of oxidation.

NH 3-SCR on Cu, Fe and Cu + Fe exchanged beta and SSZ-13 catalysts: Hydrothermal aging and propylene poisoning effects

DOE PAGES

Wang, Aiyong; Wang, Yilin; Walter, Eric D.; ...

2017-10-07

Cu, Fe and Cu + Fe ion exchanged Beta and SSZ-13 catalysts were prepared by solution ion exchange using commercial NH 4/Beta, and NH 4/SSZ-13 that was prepared in-house. To study hydrothermal aging effects, Beta supported catalysts were aged hydrothermally at 700 °C and SSZ-13 supported catalysts were aged at 750 °C. In order to reveal the effects of Fe addition in the co-exchanged catalysts, these catalysts were characterized by means of powder X-ray diffraction (XRD), N 2 adsorption-desorption, electron paramagnetic resonance (EPR), 27Al-nuclear magnetic resonance ( 27Al-NMR) and propylene coking followed with temperature programmed reaction (TPR), and further testedmore » with standard NH 3-SCR with and without the presence of propylene. Collectively, the catalyst characterizations and reaction testing indicated minor beneficial effects of Fe addition in Cu,Fe/Beta, where NH 3-SCR activity, N 2 selectivity and hydrothermal stability were all slightly improved. In contrast, Fe addition did not show apparent beneficial effects in low-temperature SCR for the Cu,Fe/SSZ-13 case. In conclusion, at elevated reaction temperatures, however, the presence of Fe indeed considerably improved NO conversion and N 2 selectivity for the hydrothermally aged Cu,Fe/SSZ-13 catalyst in the presence of propylene.« less

NH 3-SCR on Cu, Fe and Cu + Fe exchanged beta and SSZ-13 catalysts: Hydrothermal aging and propylene poisoning effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Aiyong; Wang, Yilin; Walter, Eric D.

Cu, Fe and Cu + Fe ion exchanged Beta and SSZ-13 catalysts were prepared by solution ion exchange using commercial NH 4/Beta, and NH 4/SSZ-13 that was prepared in-house. To study hydrothermal aging effects, Beta supported catalysts were aged hydrothermally at 700 °C and SSZ-13 supported catalysts were aged at 750 °C. In order to reveal the effects of Fe addition in the co-exchanged catalysts, these catalysts were characterized by means of powder X-ray diffraction (XRD), N 2 adsorption-desorption, electron paramagnetic resonance (EPR), 27Al-nuclear magnetic resonance ( 27Al-NMR) and propylene coking followed with temperature programmed reaction (TPR), and further testedmore » with standard NH 3-SCR with and without the presence of propylene. Collectively, the catalyst characterizations and reaction testing indicated minor beneficial effects of Fe addition in Cu,Fe/Beta, where NH 3-SCR activity, N 2 selectivity and hydrothermal stability were all slightly improved. In contrast, Fe addition did not show apparent beneficial effects in low-temperature SCR for the Cu,Fe/SSZ-13 case. In conclusion, at elevated reaction temperatures, however, the presence of Fe indeed considerably improved NO conversion and N 2 selectivity for the hydrothermally aged Cu,Fe/SSZ-13 catalyst in the presence of propylene.« less

Failure Mechanisms of SAC/Fe-Ni Solder Joints During Thermal Cycling

NASA Astrophysics Data System (ADS)

Gao, Li-Yin; Liu, Zhi-Quan; Li, Cai-Fu

2017-08-01

Thermal cycling tests have been conducted on Sn-Ag-Cu/Fe- xNi ( x = 73 wt.% or 45 wt.%) and Sn-Ag-Cu/Cu solder joints according to the Joint Electron Device Engineering Council industrial standard to study their interfacial reliability under thermal stress. The interfacial intermetallic compounds formed for solder joints on Cu, Fe-73Ni, and Fe-45Ni were 4.5 μm, 1.7 μm, and 1.4 μm thick, respectively, after 3000 cycles, demonstrating excellent diffusion barrier effect of Fe-Ni under bump metallization (UBM). Also, two deformation modes, viz. solder extrusion and fatigue crack formation, were observed by scanning electron microscopy and three-dimensional x-ray microscopy. Solder extrusion dominated for solder joints on Cu, while fatigue cracks dominated for solder joints on Fe-45Ni and both modes were detected for those on Fe-73Ni. Solder joints on Fe-Ni presented inferior reliability during thermal cycling compared with those on Cu, with characteristic lifetime of 3441 h, 3190 h, and 1247 h for Cu, Fe-73Ni, and Fe-45Ni UBM, respectively. This degradation of the interfacial reliability for solder joints on Fe-Ni is attributed to the mismatch in coefficient of thermal expansion (CTE) at interconnection level. The CTE mismatch at microstructure level was also analyzed by electron backscatter diffraction for clearer identification of recrystallization-related deformation mechanisms.

Electronic structure of the iron-based superconductor (La,Eu)FeAsO1-xFx investigated by laser photoemission spectroscopy

NASA Astrophysics Data System (ADS)

Malaeb, Walid; Awad, Ramadan; Hibino, Taku; Kamihara, Yoichi; Kondo, Takeshi; Shin, Shik

2018-05-01

We have implemented laser photoemission spectroscopy (PES) to investigate the electronic structure of the iron-based superconductor (La,Eu)FeAsO1-xFx (LaEu1111) which is an interesting compound in the "1111" family showing a high value of the superconducting (SC) transition temperature (Tc) due to Eu doping. At least two energy scales were observed from the PES data in the SC compound: One at ∼14 meV closing around Tc and thus corresponding to the SC gap. Another energy scale appears at ∼35 meV and survives at temperatures above Tc which represents the pseudogap (PG). The non-SC sample (La,Eu)FeAsO shows a PG at ∼ 41 meV. These observations in this new superconductor are consistent with the general trend followed by other compounds in the "1111" family.

A visible-light-excited europium(III) complex-based luminescent probe for visualizing copper ions and hydrogen sulfide in living cells

NASA Astrophysics Data System (ADS)

Wang, Yiren; Wang, Huan; Yang, Mei; Yuan, Jingli; Wu, Jing

2018-01-01

Development of visible-light-excited lanthanide (III) complex-based luminescent probes is highly appealing due to their superiority of less damage to the living biosystems over the conventional UV-light-excited ones. In this work, a visible-light-excited europium (III) complex-based luminescent probe, BPED-BHHCT-Eu3+-BPT, has been designed and synthesized by conjugating the Cu2+-binding N,N-bis(2-pyridylmethyl)ethanediamine (BPED) to a tetradentate β-diketone ligand 4,4‧-bis(1″,1″,1″,2″,2″,3″,3″-heptafluoro-4″,6″-hexanedione-6″-yl)chlorosulfo-o-terphenyl (BHHCT) and coordinating with a coligand 2-(N,N-diethylanilin-4-yl)-4,6-bis(pyrazol-1-yl)-1,3,5-triazine) (BPT) for the time-gated luminescence detection of Cu2+ ions and hydrogen sulfide (H2S) in living cells. BPED-BHHCT-Eu3+-BPT exhibited a sharp excitation peak at 407 nm and a wide excitation window extending to beyond 460 nm. Upon its reaction with Cu2+ ions, the luminescence of BPED-BHHCT-Eu3+-BPT was efficiently quenched, which could be reversibly restored by the addition of H2S due to the strong affinity between Cu2+ ions and H2S. The "on-off-on" type luminescence behavior of BPED-BHHCT-Eu3+-BPT towards Cu2+ ions and H2S enabled the sensing of the two species with high sensitivity and selectivity. The performances of BPED-BHHCT-Eu3+-BPT for visualizing intracellular Cu2+ ions and H2S were investigated, and the results have demonstrated the practical applicability of the probe for molecular imaging of cells.

Electronic, Magnetic, and Redox Properties of [MFe(3)S(4)] Clusters (M = Cd, Cu, Cr) in Pyrococcus furiosus Ferredoxin.

PubMed

Staples, Christopher R.; Dhawan, Ish K.; Finnegan, Michael G.; Dwinell, Derek A.; Zhou, Zhi Hao; Huang, Heshu; Verhagen, Marc F. J. M.; Adams, Michael W. W.; Johnson, Michael K.

1997-12-03

The ground- and excited-state properties of heterometallic [CuFe(3)S(4)](2+,+), [CdFe(3)S(4)](2+,+), and [CrFe(3)S(4)](2+,+) cubane clusters assembled in Pyrococcus furiosus ferredoxin have been investigated by the combination of EPR and variable-temperature/variable-field magnetic circular dichroism (MCD) studies. The results indicate Cd(2+) incorporation into [Fe(3)S(4)](0,-) cluster fragments to yield S = 2 [CdFe(3)S(4)](2+) and S = (5)/(2) [CdFe(3)S(4)](+) clusters and Cu(+) incorporation into [Fe(3)S(4)](+,0) cluster fragments to yield S = (1)/(2) [CuFe(3)S(4)](2+) and S = 2 [CuFe(3)S(4)](+) clusters. This is the first report of the preparation of cubane type [CrFe(3)S(4)](2+,+) clusters, and the combination of EPR and MCD results indicates S = 0 and S = (3)/(2) ground states for the oxidized and reduced forms, respectively. Midpoint potentials for the [CdFe(3)S(4)](2+,+), [CrFe(3)S(4)](2+,+), and [CuFe(3)S(4)](2+,+) couples, E(m) = -470 +/- 15, -440 +/- 10, and +190 +/- 10 mV (vs NHE), respectively, were determined by EPR-monitored redox titrations or direct electrochemistry at a glassy carbon electrode. The trends in redox potential, ground-state spin, and electron delocalization of [MFe(3)S(4)](2+,+) clusters in P. furiosus ferredoxin are discussed as a function of heterometal (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Tl).

Social marketing improved the consumption of iron-fortified soy sauce among women in China.

PubMed

Sun, Xinying; Guo, Yan; Wang, Sisun; Sun, Jing

2007-01-01

To test the feasibility and effectiveness of social marketing on the improvement of women's knowledge, attitudes, and behaviors regarding iron-fortified soy sauce (FeSS). A community-based intervention was conducted among 4 groups, experimental rural (E(R)), control rural (C(R)), experimental urban (E(U)), and control urban (C(U)). Urban and rural areas in Guizhou province, China. Women 19 to 70 years old (n = 193 in rural areas and n = 179 in urban areas). A mass-media campaign to promote use of FeSS was conducted throughout Guizhou province. In the intervention areas, social marketing strategies using integrated 6 Ps (product, price, place, promotion, policy, and partnership) were implemented from December 2004 to February 2006. Knowledge of FeSS; benefits, barriers, and intention to purchase; availability of FeSS; behaviors regarding purchase and use of FeSS. Analysis of covariance, paired T test and cross-tabulations were used. The alpha level was set at .05. Compared with the baseline, perceived benefits of FeSS, barriers (BARRI) and intention to buy (INTEN) significantly improved within both experimental groups (P < .01 or .001). The only improvement in control groups was for BARRI in C(R) (P < .001). Availability of FeSS increased in all areas. Purchase and use of FeSS in rural and urban intervention groups increased by nearly 30% more than those in control groups. Social marketing of FeSS is feasible and effective to improve knowledge, perception (perceived benefits and overcoming barriers), intention to purchase, and consumption of FeSS among women in Guizhou, China.

Copper-nickel superalloys as inert alloy anodes for aluminum electrolysis

NASA Astrophysics Data System (ADS)

Shi, Zhongning; Xu, Junli; Qiu, Zhuxian; Wang, Zhaowen; Gao, Bingliang

2003-11-01

The superalloys Cu-Ni-Al, Cu-Ni-Fe, and Cu-Ni-Cr were studied as anodes for aluminum electrolysis. The alloys were tested for corrosion in acidic electrolyte molten salt and for oxidation in both air and oxygen. The results showed that the Cu-Ni-Al anodes possess excellent resistance to oxidation and corrosion, and the oxidation rates of Cu-Ni-Fe and Cu-Ni-Al anodes were slower than those of pure copper or nickel. During electrolysis, the cell voltage of the Cu-Ni-Al anode was affected most by the concentration of alumina in cryolite molten salt. The Cu-Ni-Fe anode exhibited corrosion resistance in electrolyte molten salt. Comparatively, the Cu-Ni-Cr anode showed poor resistance to oxidation and corrosion. The testing found that further study is warranted on the use of Cu-Ni-Al and Cu-Ni-Fe as inert alloy anodes.

Activities in Cu2S-FeS-SnS melts at 1200 °C

NASA Astrophysics Data System (ADS)

Eric, R. Hurman

1993-04-01

The dew-point technique was used to measure the vapor pressures of SnS over liquid sulfides of the system Cu2S-FeS-SnS at 1200 °C. Activities of SnS were generated from the measured vapor pressures of SnS. Activities of Cu2S and FeS were evaluated both in binary and ternary melts by Gibbs-Duhem calculations from the known SnS activity data. The systems Cu2S-SnS and Cu2S-FeS exhibit negative departures from ideal behavior, while FeS-SnS melts exhibit positive deviations.

Interplay of magnetism and superconductivity in EuFe2(As1-xPx)2 single crystals probed by muon spin rotation and 57Fe Mössbauer spectroscopy

NASA Astrophysics Data System (ADS)

Goltz, T.; Kamusella, S.; Jeevan, H. S.; Gegenwart, P.; Luetkens, H.; Materne, P.; Spehling, J.; Sarkar, R.; Klauss, H.-H.

2014-12-01

We present our results of a local probe study on EuFe2(As1-xPx)2 single crystals with x=0.13, 0.19 and 0.28 by means of muon spin rotation and 57Fe Mössbauer spectroscopy. We focus our discussion on the sample with x=0.19 viz. at the optimal substitution level, where bulk superconductivity (TSC = 28 K) sets in above static europium order (TEu = 20 K) but well below the onset of the iron antiferromagnetic (AFM) transition (~100 K). We find enhanced spin dynamics in the Fe sublattice closely above TSC and propose that these are related to enhanced Eu fluctuations due to the evident coupling of both sublattices observed in our experiments.

As(V) removal capacity of FeCu bimetallic nanoparticles in aqueous solutions: The influence of Cu content and morphologic changes in bimetallic nanoparticles.

PubMed

Sepúlveda, Pamela; Rubio, María A; Baltazar, Samuel E; Rojas-Nunez, J; Sánchez Llamazares, J L; Garcia, Alejandra García; Arancibia-Miranda, Nicolás

2018-08-15

In this study, bimetallic nanoparticles (BMNPs) with different mass ratios of Cu and Fe were evaluated. The influence of the morphology on the removal of pollutants was explored through theoretical and experimental studies, which revealed the best structure for removing arsenate (As(V)) in aqueous systems. To evidence the surface characteristics and differences among BMNPs with different mass proportions of Fe and Cu, several characterization techniques were used. Microscopy techniques and molecular dynamics simulations were applied to determine the differences in morphology and structure. In addition, X-ray diffraction (XRD) was used to determine the presence of various oxides. Finally, the magnetization response was evaluated, revealing differences among the materials. Our cumulative data show that BMNPs with low amounts of Cu (Fe 0.9 Cu 0.1 ) had a non-uniform core-shell structure with agglomerate-type chains of magnetite, whereas a Janus-like structure was observed in BMNPs with high amounts of Cu (Fe 0.5 Cu 0.5 ). However, a non-uniform core-shell structure (Fe 0.9 Cu 0.1 ) facilitated electron transfer among Fe, Cu and As, which increased the adsorption rate (k), capacity (q e ) and intensity (n). The mechanism of As removal was also explored in a comparative study of the phase and morphology of BMNPs pre- and post-sorption. Copyright © 2018 Elsevier Inc. All rights reserved.

Adsorption of multi-heavy metals Zn and Cu onto surficial sediments: modeling and adsorption capacity analysis.

PubMed

Li, Shanshan; Zhang, Chen; Wang, Meng; Li, Yu

2014-01-01

Improved multiple regression adsorption models (IMRAMs) was developed to estimate the adsorption capacity of the components [Fe oxides (Fe), Mn oxides (Mn), organic materials (OMs), residuals] in surficial sediments for multi-heavy metal Zn and Cu. IMRAM is an improved version over MRAM, which introduces a computer program in the model developing process. As MRAM, Zn(Cu) IMRAM, and Cu(Zn) IMRAM again confirmed that there is significant interaction effects that control the adsorption of compounded Zn and Cu, which was neglected by additional adsorption model. The verification experiment shows that the relative deviation of the IMRAMs is less than 13%. It is revealed by the IMRAMs that Mn, which has the greatest adsorption capability for compounded Zn and Cu (54.889 and 161.180 mg/l, respectively), follows by interference adsorption capacity of Fe/Mn (-1.072 and -24.591 mg/l respectively). Zn and Cu influence each other through different mechanisms. When Zn is the adsorbate, compounded Cu mainly affects the adsorption capacities of Fe/Mn and Fe/Mn/OMs; while when Cu is the adsorbate, compounded Zn mainly exerts its effect on Mn, Fe/Mn, and Mn/OMs. It also shows that the compounded Zn or Cu weakened the interference adsorption of Fe/Mn, and meanwhile, strengthened the interference adsorption of Mn/OMs.

Giant magnetoresistance (GMR) behavior of electrodeposited NiFe/Cu multilayers: Dependence of non-magnetic and magnetic layer thicknesses

NASA Astrophysics Data System (ADS)

Kuru, Hilal; Kockar, Hakan; Alper, Mursel

2017-12-01

Giant magnetoresistance (GMR) behavior in electrodeposited NiFe/Cu multilayers was investigated as a function of non-magnetic (Cu) and ferromagnetic (NiFe) layer thicknesses, respectively. Prior to the GMR analysis, structural and magnetic analyses of the multilayers were also studied. The elemental analysis of the multilayers indicated that the Cu and Ni content in the multilayers increase with increasing Cu and NiFe layer thickness, respectively. The structural studies by X-ray diffraction revealed that all multilayers have face centred cubic structure with preferred (1 1 0) crystal orientation as their substrates. The magnetic properties studied with the vibrating sample magnetometer showed that the magnetizations of the samples are significantly affected by the layer thicknesses. Saturation magnetisation, Ms increases from 45 to 225 emu/cm3 with increasing NiFe layer thickness. The increase in the Ni content of the multilayers with a small Fe content causes an increase in the Ms. And, the coercivities ranging from 2 to 24 Oe are between the soft and hard magnetic properties. Also, the magnetic easy axis of the multilayers was found to be in the film plane. Magnetoresistance measurements showed that all multilayers exhibited the GMR behavior. The GMR magnitude increases with increasing Cu layer thickness and reaches its maximum value of 10% at the Cu layer thickness of 1 nm, then it decreases. And similarly, the GMR magnitude increases and reaches highest value of pure GMR (10%) for the NiFe layer thickness of 3 nm, and beyond this point GMR decreases with increasing NiFe layer thickness. Some small component of the anisotropic magnetoresistance was also observed at thin Cu and thick NiFe layer thicknesses. It is seen that the highest GMR values up to 10% were obtained in electrodeposited NiFe/Cu multilayers up to now. The structural, magnetic and magnetoresistance properties of the NiFe/Cu were reported via the variations of the thicknesses of Cu and NiFe layers with stressing the role of layer thicknesses on the high GMR behavior.

A comprehensive study of magnetic exchanges in the layered oxychalcogenides Sr 3 Fe 2 O 5 Cu 2 Q 2 ( Q = S, Se)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lü, Minfeng; Mentré, Olivier; Gordon, Elijah E.

2017-12-01

The layered oxysulfide Sr3Fe2O5Cu2S2 was prepared, and its crystal structure and magnetic properties were characterized by synchrotron X-ray diffraction (XRD), powder neutron diffraction (PND), Mössbauer spectroscopy measurements and by density functional theory (DFT) calculations. In addition, the spin exchange interactions leading to the ordered magnetic structure of Sr3Fe2O5Cu2S2 were compared with those of its selenium analogue Sr3Fe2O5Cu2Se2. The oxysulfide Sr3Fe2O5Cu2S2 adopts a G-type antiferromagnetic (AFM) structure at a temperature in the range 485–512 K, which is comparable with the three-dimensional (3D) AFM ordering temperature, TN ≈ 490 K, found for Sr3Fe2O5Cu2Se2. Consistent with this observation, the spin exchange interactions ofmore » the magnetic (Sr3Fe2O5)2+ layers are slightly greater (but comparable) for oxysulfide than for the oxyselenide. Attempts to reduce or oxidize Sr3Fe2O5Cu2S2 using topochemical routes yield metallic Fe.« less

Conditions and mechanisms for the formation of nano-sized Delafossite (CuFeO2) at temperatures ≤90 °C in aqueous solution

NASA Astrophysics Data System (ADS)

John, Melanie; Heuss-Aßbichler, Soraya; Ullrich, Aladin

2016-02-01

In this study, we present the mechanism of CuFeO2 formation in aqueous solution at low temperatures ≤90 °C, using sulfate salts as reactants. Furthermore, we demonstrate the influence of experimental conditions (alkalization, reaction and ageing temperature and time) on the synthesized nanoparticles. In all cases, GR-SO4, a Fe(II-III) layered double hydroxysulphate (Fe2+4Fe3+2(OH)12·SO4) and Cu2O precipitate first. During further OH- supply GR-SO4 oxidizes and forms Fe10O14(OH)2, Cu2O and CuFeO2 crystals. Due to the high pH further CuFeO2 crystals grow at the cost of the unstable intermediate products. The reaction rate increases with increasing ageing temperature, reaction pH and, in particular, NaOH concentrations in the solution. As a result, highly crystalline CuFeO2 (3R and 2H polytypes) nanoparticles showing hexagonal morphology can be synthesized at 70 °C within 10 h or at 50 °C within 1 week. The formation of 2H polytype is favored by additional OH- supply during the pH-stat time and rather low temperatures.

Thermodynamic analysis of binary Fe{sub 85}B{sub 15} to quinary Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloys for primary crystallizations of α-Fe in nanocrystalline soft magnetic alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeuchi, A., E-mail: takeuchi@imr.tohoku.ac.jp; Zhang, Y.; Takenaka, K.

2015-05-07

Fe-based Fe{sub 85}B{sub 15}, Fe{sub 84}B{sub 15}Cu{sub 1}, Fe{sub 82}Si{sub 2}B{sub 15}Cu{sub 1}, Fe{sub 85}Si{sub 2}B{sub 12}Cu{sub 1}, and Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} (NANOMET{sup ®}) alloys were experimental and computational analyzed to clarify the features of NANOMET that exhibits high saturation magnetic flux density (B{sub s}) nearly 1.9 T and low core loss than conventional nanocrystalline soft magnetic alloys. The X-ray diffraction analysis for ribbon specimens produced experimentally by melt spinning from melts revealed that the samples were almost formed into an amorphous single phase. Then, the as-quenched samples were analyzed with differential scanning calorimeter (DSC) experimentally for exothermicmore » enthalpies of the primary and secondary crystallizations (ΔH{sub x1} and ΔH{sub x2}) and their crystallization temperatures (T{sub x1} and T{sub x2}), respectively. The ratio ΔH{sub x1}/ΔH{sub x2} measured by DSC experimentally tended to be extremely high for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy, and this tendency was reproduced by the analysis with commercial software, Thermo-Calc, with database for Fe-based alloys, TCFE7 for Gibbs free energy (G) assessments. The calculations exhibit that a volume fraction (V{sub f}) of α-Fe tends to increase from 0.56 for the Fe{sub 85}B{sub 15} to 0.75 for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy. The computational analysis of the alloys for G of α-Fe and amorphous phases (G{sub α-Fe} and G{sub amor}) shows that a relationship G{sub α-Fe} ∼ G{sub amor} holds for the Fe{sub 85}Si{sub 2}B{sub 12}Cu{sub 1}, whereas G{sub α-Fe} < G{sub amor} for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy at T{sub x1} and that an extremely high V{sub f} = 0.75 was achieved for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy by including 2.8 at. % Si and 4.5 at. % P into α-Fe. These computational results indicate that the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy barely forms amorphous phase, which, in turn, leads to high V{sub f} and resultant high B{sub s}.« less

Minor-Cu doped soft magnetic Fe-based FeCoBCSiCu amorphous alloys with high saturation magnetization

NASA Astrophysics Data System (ADS)

Li, Yanhui; Wang, Zhenmin; Zhang, Wei

2018-05-01

The effects of Cu alloying on the amorphous-forming ability (AFA) and magnetic properties of the P-free Fe81Co5B11C2Si1 amorphous alloy were investigated. Addition of ≤ 1.0 at.% Cu enhances the AFA of the base alloy without significant deterioration of the soft magnetic properties. The Fe80.5Co5B11C2Si1Cu0.5 alloy with the largest critical thickness for amorphous formation of ˜35 μm possesses a high saturation magnetization (Bs) of ˜1.78 T, low coercivity of ˜14.6 A/m, and good bending ductility upon annealing in a wide temperature range of 513-553 K with maintaining the amorphous state. The fabrication of the new high-Fe-content Fe-Co-B-C-Si-Cu amorphous alloys by minor doping of Cu gives a guideline to developing high Bs amorphous alloys with excellent AFA.

Reduction of CO2 to low carbon alcohols on CuO FCs/Fe2O3 NTs catalyst with photoelectric dual catalytic interfaces

NASA Astrophysics Data System (ADS)

Li, Peiqiang; Wang, Huying; Xu, Jinfeng; Jing, Hua; Zhang, Jun; Han, Haixiang; Lu, Fusui

2013-11-01

In this paper, the CuO FCs/Fe2O3 NTs catalyst was obtained after Fe2O3 nanotubes (Fe2O3 NTs) were decorated with CuO flower clusters (CuO FCs) by the pulse electrochemical deposition method. The in situ vertically aligned Fe2O3 NTs were prepared on the ferrous substrate by a potentiostatic anodization method. The SEM result showed the volcano-like Fe2O3 NTs were arranged in order and the CuO FCs constituted of flaky CuO distributed on the Fe2O3 NTs surface uniformly. After CuO FCs were loaded on Fe2O3 NTs, the absorption of visible light was enhanced noticeably, and its band gap narrowed to 1.78 eV from 2.03 eV. The conduction band and valence band locating at -0.73 eV and 1.05 eV, respectively were further obtained. In the PEC reduction of CO2 process, methanol and ethanol were two major products identified by chromatography. Their contents reached 1.00 mmol L-1 cm-2 and 107.38 μmol L-1 cm-2 after 6 h, respectively. This high-efficiency catalyst with photoelectric dual catalytic interfaces has a great guidance and reference significance for CO2 reduction to liquid carbon fuels.In this paper, the CuO FCs/Fe2O3 NTs catalyst was obtained after Fe2O3 nanotubes (Fe2O3 NTs) were decorated with CuO flower clusters (CuO FCs) by the pulse electrochemical deposition method. The in situ vertically aligned Fe2O3 NTs were prepared on the ferrous substrate by a potentiostatic anodization method. The SEM result showed the volcano-like Fe2O3 NTs were arranged in order and the CuO FCs constituted of flaky CuO distributed on the Fe2O3 NTs surface uniformly. After CuO FCs were loaded on Fe2O3 NTs, the absorption of visible light was enhanced noticeably, and its band gap narrowed to 1.78 eV from 2.03 eV. The conduction band and valence band locating at -0.73 eV and 1.05 eV, respectively were further obtained. In the PEC reduction of CO2 process, methanol and ethanol were two major products identified by chromatography. Their contents reached 1.00 mmol L-1 cm-2 and 107.38 μmol L-1 cm-2 after 6 h, respectively. This high-efficiency catalyst with photoelectric dual catalytic interfaces has a great guidance and reference significance for CO2 reduction to liquid carbon fuels. Electronic supplementary information (ESI) available: Reduction of CO2 to low carbon alcohols on CuO FCs/Fe2O3 NTs catalyst with photoelectric dual catalytic interfaces. See DOI: 10.1039/c3nr03352j

Fe{sub 3}O{sub 4}/CuO/ZnO/Nano graphene platelets (Fe{sub 3}O{sub 4}/CuO/ZnO/NGP) composites prepared by sol-gel method with enhanced sonocatalytic activity for the removal of dye

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendry, Tju; Taufik, Ardiansyah; Saleh, Rosari, E-mail: rosari.saleh@gmail.com, E-mail: rosari.saleh@ui.ac.id

2016-04-19

In this study, an attempt has been made to synthesize nanographene platelets coupled with Fe3O4/CuO/ZnO (Fe3O4/CuO/ZnO/NGP) with various ZnO loadings using a two step methods, sol-gel followed by hydrothermal method. Characterization was carried out by X-ray diffraction, energy-dispersive X-ray spectroscopy and vibrating sample magnetometer. The sonocatalytic performance was evaluated by degradation of methylene blue under ultrasonic irradiation.The Fe3O4/CuO/ZnO/NGP showed superior sonocatalytic activity than the Fe3O4/CuO/ZnO materials. They also showed high stability and can be easily separated from the reaction system for recycling process.

Microstructure and mechanical properties of aluminium matrix composites reinforced by Al{sub 62}Cu{sub 25.5}Fe{sub 12.5} melt spun ribbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lityńska-Dobrzyńska, Lidia, E-mail: l.litynska@imim.pl; Mitka, Mikołaj; Góral, Anna

Aluminium matrix composites containing 15, 30 and 50 vol.% of pulverized Al{sub 62}Cu{sub 25.5}Fe{sub 12.5} (in at.%) melt spun ribbons have been prepared by a vacuum hot pressing (T = 673 K, P = 600 MPa). The microstructure of the initial ribbon and the composites was investigated using X-ray, scanning and transmission electron microscopy. In the as-spun ribbon the quasicrystalline icosahedral phase (i-phase) coexisted with the cubic copper rich β-Al(Cu, Fe) intermetallic compound. The phase composition of Al-Cu-Fe particles changed after consolidation process and the i-phase transformed partially to the ω-Al{sub 70}Cu{sub 20}Fe{sub 10} phase. Additionally, the Θ-Al{sub 2}Cu phasemore » formed at the α(Al)/Al-Cu-Fe particle interfaces. With an increase in volume fraction of the reinforcement the hardness of the composites increased up to HV = 180 for the highest amount of added particles. The ultimate compression strength of the same sample reached the value of 545 MPa. - Highlights: • Al and 15, 30, 50% of pulverized Al{sub 62}Cu{sub 25.5}Fe{sub 12.5} melt spun ribbon were consolidated. • The initial ribbon consisted of the icosahedral i-phase and copper rich β-Al(Cu, Fe). • The i-phase partially transforms to ω-Al{sub 7}Cu{sub 2}Fe phase in all composites. • Increase of microhardness and compressive strength with content of reinforcement • Ultimate compression strength 545 MPa for 50% of added particles.« less

Solid state 31phosphorus nuclear magnetic resonance of iron-, manganese-, and copper-containing synthetic hydroxyapatites

NASA Technical Reports Server (NTRS)

Sutter, B.; Taylor, R. E.; Hossner, L. R.; Ming, D. W.

2002-01-01

The incorporation of micronutrients into synthetic hydroxyapatite (SHA) is proposed for slow release of these nutrients to crops in the National Aeronautics and Space Administration's (NASA's) Advanced Life Support (ALS) program for Lunar or Martian outposts. Solid state 31P nuclear magnetic resonance (NMR) was utilized to examine the paramagnetic effects of Fe3+, Mn2+, and Cu2+ to determine if they were incorporated into the SHA structure. Separate Fe3+, Mn2+, and Cu2+ containing SHA materials along with a transition metal free SHA (pure-SHA) were synthesized using a precipitation method. The proximity (<1 nm) of the transition metals to the 31P nuclei of SHA were apparent when comparing the integrated 31P signal intensities of the pure-SHA (87 arbitrary units g-1) with the Fe-, Mn-, and Cu-SHA materials (37-71 arbitrary units g-1). The lower integrated 31P signal intensities of the Fe-, Mn-, and Cu-SHA materials relative to the pure-SHA suggested that Fe3+, Mn2+, and Cu2+ were incorporated in the SHA structure. Further support for Fe3+, Mn2+, and Cu2+ incorporation was demonstrated by the reduced spin-lattice relaxation constants of the Fe-, Mn-, and Cu-SHA materials (T'=0.075-0.434s) relative to pure-SHA (T1=58.4s). Inversion recovery spectra indicated that Fe3+, Mn2+, and Cu2+ were not homogeneously distributed about the 31P nuclei in the SHA structure. Extraction with diethylene-triamine-penta-acetic acid (DTPA) suggested that between 50 and 80% of the total starting metal concentrations were incorporated in the SHA structure. Iron-, Mn-, and Cu-containing SHA are potential slow release sources of Fe, Mn, and Cu in the ALS cropping system.

Ab-initio calculation of EuO doped with 5% of (Ti, V, Cr and Fe): GGA and SIC approximation

NASA Astrophysics Data System (ADS)

Rouchdi, M.; Salmani, E.; Bekkioui, N.; Ez-Zahraouy, H.; Hassanain, N.; Benyoussef, A.; Mzerd, A.

2017-12-01

In this research, a simple theoretical method is proposed to investigate the electronic, magnetic and optical properties of Europium oxide (EuO) doped with 5% of (Ti, V, Cr and Fe). For a basic understanding of these properties, we employed Density-Functional Theory (DFT) based calculations with the Korringa-Kohn-Rostoker code (KKR) combined with the Coherent Potential Approximation (CPA). Also we investigated the half-metallic ferromagnetic behavior of EuO doped with 5% of (Ti, V, Cr and Fe) within the self-interaction-corrected Generalized Gradient Approximation (GGA-SIC). Our calculated results revealed that the Eu0.95TM0.05O is ferromagnetic with a high transition temperature. Moreover, the optical absorption spectra revealed that the half metallicity has been also predicted.

Influence of Cu on modifying the beta phase and enhancing the mechanical properties of recycled Al-Si-Fe cast alloys.

PubMed

Basak, C B; Babu, N Hari

2017-07-18

High iron impurity affects the castability and the tensile properties of the recycled Al-Si alloys due to the presence of the Fe containing intermetallic β-Al 9 Fe 2 Si 2 phase. To date only Mn addition is known to transform the β-Al 9 Fe 2 Si 2 phase in the Al-Si-Fe system. However, for the first time, as reported here, it is shown that β-phase transforms to the ω-Al 7 Cu 2 Fe phase in the presence of Cu, after solutionization at 793 K. The ω-phase decomposes below 673 K resulting into the formation of θ-Al 2 Cu phase. However, the present thermodynamic description of the Al-Si-Fe-Cu system needs finer tuning to accurately predict the stability of the ω-phase in these alloys. In the present study, an attempt was made to enhance the strength of Al-6wt%Si-2wt%Fe model recycled cast alloy with different amount of Cu addition. Microstructural and XRD analysis were carried out in detail to show the influence of Cu and the stability range of the ω-phase. Tensile properties and micro-hardness values are also reported for both as-cast and solutionized alloys with different amount of Cu without and with ageing treatment at 473 K. The increase in strength due to addition of Cu, in Fe-rich Al-Si alloys is promising from the alloy recyclability point of view.

Spinel, YbFe2O4, and Yb2Fe3O7 types of structure for compounds in the In2O3 and Sc2O3-A2O3-BO systems (A: Fe, Ga, or Al; B: Mg, Mn, Fe, Ni, Cu, or Zn) at temperatures over 1000C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kimizuka, N.; Mohri, T.

In the Sc2O3-Ga2O3-CuO, Sc2O3-Ga2O3-ZnO, and Sc2O3-Al2O3-CuO systems, ScGaCuO4, ScGaZnO4, and ScAlCuO4 with the YbFe2O4-type structure and Sc2Ga2CuO7 with the Yb2Fe3O7-type structure were obtained. In the In2O3-A2O3-BO systems (A: Fe, Ga, or Al; B: Mg, Mn, Fe, Ni, or Zn), InGaFeO4, InGaNiO4, and InFeT MgO4 with the spinel structure, InGaZnO4, InGaMgO4, and InAl-CuO4 with the YbFe2O4-type structure, and In2Ga2MnO7 and In2Ga2ZnO7 with the Yb2Fe3O7-type structure were obtained. InGaMnO4 and InFe2O4 had both the YbFe2O4-type and spinel-type structures. The revised classification for the crystal structures of AB2O4 compounds is presented, based upon the coordination numbers of constituent A and B cations. 5more » references, 2 tables.« less

Integrated photooxidative-extractive desulfurization system for fuel oil using Cu, Fe and Cu-Fe/TiO2 and eutectic based ionic liquids: Effect of calcination temperature and duration

NASA Astrophysics Data System (ADS)

Zaid, Hayyiratul Fatimah Mohd; Kait, Chong Fai; Mutalib, Mohamed Ibrahim Abdul

2014-10-01

Photocatalyts TiO2 doped with Cu, Fe and Cu-Fe metal at different calcination temperature and duration were successfully prepared and characterized. Photocatalytic oxidative desulfurization of model oil containing dibenzothiophene as the sulfur compound (100 ppm) using the prepared photocatalyst was investigated. The photocatalyst calcined at 500°C and duration of 1 h showed the best performance.

Microstructures and Mechanical Properties of NiTiFeAlCu High-Entropy Alloys with Exceptional Nano-precipitates

NASA Astrophysics Data System (ADS)

Zhang, Yanqiu; Wang, Sibing; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong

2017-01-01

Three novel NiTiFeAlCu high-entropy alloys, which consist of nano-precipitates with face-centered cubic structure and matrix with body-centered cubic structure, were fabricated to investigate microstructures and mechanical properties. With the increase in Ni and Ti contents, the strength of NiTiFeAlCu alloy is enhanced, while the plasticity of NiTiFeAlCu alloy is lowered. Plenty of dislocations can be observed in the Ni32Ti32Fe12Al12Cu12 high-entropy alloy. The size of nano-precipitates decreases with the increase in Ni and Ti contents, while lattice distortion becomes more and more severe with the increase in Ni and Ti contents. The existence of nano-precipitates, dislocations and lattice distortion is responsible for the increase in the strength of NiTiFeAlCu alloy, but it has an adverse influence on the plasticity of NiTiFeAlCu alloy. Ni20Ti20Fe20Al20Cu20 alloy exhibits the substantial ability of plastic deformation and a characteristic of steady flow at 850 and 1000 °C. This phenomenon is attributed to a competition between the increase in the dislocation density induced by plastic strain and the decrease in the dislocation density due to the dynamic recrystallization.

Copper(II) cyanido-bridged bimetallic nitroprusside-based complexes: Syntheses, X-ray structures, magnetic properties, 57Fe Mössbauer spectroscopy and thermal studies

NASA Astrophysics Data System (ADS)

Trávníček, Zdeněk; Herchel, Radovan; Mikulík, Jiří; Zbořil, Radek

2010-05-01

Three heterobimetallic cyanido-bridged copper(II) nitroprusside-based complexes of the compositions [Cu(tet)Fe(CN) 5NO]·H 2O ( 1), where tet= N,N' -bis(3-aminopropyl)ethylenediamine, [Cu(hto)Fe(CN) 5NO]·2H 2O ( 2), where hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1 6,9]octadecane and [Cu(nme) 2Fe(CN) 5NO]·H 2O ( 3), where nme= N-methylethylenediamine, were synthesized and characterized by elemental analyses, 57Fe Mössbauer and FTIR spectroscopies, thermal analysis, magnetic measurements and single-crystal X-ray analysis. The products of thermal degradation processes of 2 and 3 were studied by XRD, 57Fe Mössbauer spectroscopy, SEM and EDS, and they were identified as mixtures of CuFe 2O 4 and CuO.

Preparation of TbCu7-type Sm-Fe powders by low-temperature HDDR treatment

NASA Astrophysics Data System (ADS)

Takagi, Kenta; Jinno, Miho; Ozaki, Kimihiro

2018-05-01

Low-temperature hydrogen-disproportionation-desorption-recombination (HDDR) treatment of Sm-Fe alloy powder was conducted to prepare a metastable TbCu7 type Sm-Fe alloy powder with a grain size of more than a few hundreds of nanometers. While a treatment temperature above 700 °C produced the familiar Th2Zn17 type alloy, one below 600 °C resulted in successful synthesis of the TbCu7 type Sm-Fe alloy with submicron-size grains. This TbCu7 type alloy powder, however, showed no significant improvement in magnetic properties compared to the Th2Zn17 type, as its composition was estimated to be near SmFe8.5 and thus did not achieve the expected Fe-rich composition. Therefore, cross-sectional transmission electron microscope observation of the unfinished TbCu7 type alloy powder was conducted in order to explore means of forming the Fe-rich phase.

Copper-promoted circumneutral activation of H2O2 by magnetic CuFe2O4 spinel nanoparticles: Mechanism, stoichiometric efficiency, and pathway of degrading sulfanilamide.

PubMed

Feng, Yong; Liao, Changzhong; Shih, Kaimin

2016-07-01

To evaluate the heterogeneous degradation of sulfanilamide by external energy-free Fenton-like reactions, magnetic CuFe2O4 spinel nanoparticles (NPs) were synthesized and used as catalysts for activation of hydrogen peroxide (H2O2). The physicochemical properties of the CuFe2O4 NPs were characterized with several techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and magnetometry. In the catalytic experiments, CuFe2O4 NPs/H2O2 oxidation showed the best degradation performance in the circumneutral conditions that resulted from the presence of Cu(II) on the surface of the CuFe2O4 NPs. The surface area-normalized pseudo-first-order rate constants were calculated as 2.60 × 10(-2) L m(-1) min(-1), 2.58 × 10(-3) L m(-1) min(-1), 1.92 × 10(-3) L m(-1) min(-1), and 7.30 × 10(-4) L m(-1) min(-1) for CuO, CuFe2O4 NPs, Fe3O4, and α-Fe2O3 catalysts, respectively. Thus, solid state Cu(II) was more reactive and efficient than Fe(III) in the circumneutral activation of H2O2; this finding was further supported by the results regarding the stoichiometric efficiency of H2O2. The effects of experimental parameters such as the oxidant dosage and catalyst loading were investigated. The mechanism for H2O2 activation on the spinel surface was explored and could be explained by the solid redox cycles of Fe(II)/Fe(III) and Cu(II)/Cu(I). Based on the products detected, a degradation pathway via the CS bond cleavage is proposed for the degradation of sulfanilamide. The findings of this study suggest that copper can be used as a doping metal to improve the reactivity and expand the effective pH range of iron oxides. Copyright © 2016 Elsevier Ltd. All rights reserved.

Role of Cu During Sintering of Fe0.96Cu0.04 Nanoparticles

NASA Astrophysics Data System (ADS)

Sivaprahasam, D.; Sriramamurthy, A. M.; Bysakh, S.; Sundararajan, G.; Chattopadhyay, K.

2018-04-01

Nanoparticle agglomerates of passivated Fe ( n-Fe) and Fe0.96Cu0.04 ( n-Fe0.96Cu0.04), synthesized through the levitational gas condensation (LGC) process, were compacted and sintered using the conventional powder metallurgy method. The n-Fe0.96Cu0.04 agglomerates produced lower green density than n-Fe, and when compacted under pressure beyond 200 MPa, they underwent lateral cracking during ejection attributed to the presence of a passive oxide layer. Sintering under dynamic hydrogen atmosphere can produce a higher density of compact in n-Fe0.96Cu0.04 in comparison to n-Fe. Both the results of dilatometry and thermogravimetric (TG) measurements of the samples under flowing hydrogen revealed enhancement of the sintering process as soon as the reduction of oxide layers could be accomplished. The shrinkage rate of n-Fe0.96Cu0.04 reached a value three times higher than n-Fe at a low temperature of 723 K (450 °C) during heating. This enhanced shrinkage rate was the manifestation of accumulation of Cu at the surface of the particles. The formation of a thin-surface melted layer enriched with copper during heating to isothermal holding facilitated as a medium of transport for diffusion of the elements. The compacts produced by sintering at 773 K (500 °C), with relative density 82 pct, were found to be unstable and oxidized instantly when exposed to ambient atmosphere. The stable compacts of density more than 92 pct with 300- to 450-nm grain size could only be produced when sintering was carried out at 973 K (700 °C) and beyond. The 0.22 wt pct residual oxygen obtained in the sintered compact is similar to what is used for conventional ferrous powder metallurgy products.

Effect of soil parameters on the kinetics of the displacement of Fe from FeEDDHA chelates by Cu.

PubMed

Schenkeveld, Walter D C; Reichwein, Arjen M; Temminghoff, Erwin J M; van Riemsdijk, Willem H

2012-06-28

In soil application, o,o-FeEDDHA (iron (3+) ethylene diamine-N,N'-bis(2-hydroxy phenyl acetic acid) complex) is the active ingredient of FeEDDHA chelate-based Fe fertilizers. The effectiveness of o,o-FeEDDHA is potentially compromised by the displacement of Fe from FeEDDHA by Cu. The actual impact of Cu competition is codetermined by the kinetics of the displacement reaction. In this study, the influence of soil parameters on the displacement kinetics has been examined in goethite suspensions. The displacement reaction predominantly takes place on the reactive surface rather than in solution. The rate at which the o,o-FeEDDHA concentration declined depended on the available reactive surface area, the Cu loading, and the FeEDDHA loading. Soil factors reducing FeEDDHA adsorption (high ionic strength, humic acid adsorption onto the goethite surface, and monovalent instead of divalent cations in the electrolyte) decreased the displacement rate. For meso o,o-FeEDDHA, the displacement rate equation was derived, which is first order in FeEDDHA loading and half order in Cu loading. For soil conditions, the equation can be simplified to an exponential decay function in meso o,o-FeEDDHA solution concentration.

Novel approach for removing brominated flame retardant from aquatic environments using Cu/Fe-based metal-organic frameworks: A case of hexabromocyclododecane (HBCD).

PubMed

Li, Xiang; Liu, Hongli; Jia, Xiaoshan; Li, Guiying; An, Taicheng; Gao, Yanpeng

2018-04-15

Cu and Fe based metal-organic frameworks (Cu-BTC and Fe-BTC) were synthesized via a simple solvothermal method and innovatively utilized to remove a typical nonionic brominated flame retardant, hexabromocyclododecane (HBCD), from aquatic environment. Results show that over 80% of HBCD was removed by Cu-BTC within 5h, which is 1.3 times higher than removal by Fe-BTC. Thermodynamic analysis confirms spontaneous adsorption of HBCD onto the metal-organic frameworks (MOFs). Furthermore, the Gibbs free energy of Cu-BTC (-9.11kJ/mol) is more negative than that of Fe-BTC (-5.04kJ/mol). Both adsorption isotherms of HBCD onto Cu-BTC and Fe-BTC followed the Langmuir model, indicating a typical monomolecular-layer adsorption mechanism. In addition, the water stability test of these MOFs shows that the collapse of the Cu-BTC crystal structure is significantly hindered in the aquatic environment due to adsorption of the hydrophobic HBCD. The proposed adsorption mechanism includes van der Waals and hydrophobic interactions. These findings demonstrate that Cu/Fe-BTC are promising adsorbents for the removal of hydrophobic organic pollutants from aquatic environments, and may further improve the understanding of MOF materials for environmental applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Phase diagram and neutron spin resonance of superconducting NaFe 1 - x Cu x As

DOE PAGES

Tan, Guotai; Song, Yu; Zhang, Rui; ...

2017-02-03

In this paper, we use transport and neutron scattering to study the electronic phase diagram and spin excitations of NaFe 1-xCu xAs single crystals. Similar to Co- and Ni-doped NaFeAs, a bulk superconducting phase appears near x≈2% with the suppression of stripe-type magnetic order in NaFeAs. Upon further increasing Cu concentration the system becomes insulating, culminating in an antiferromagnetically ordered insulating phase near x≈50%. Using transport measurements, we demonstrate that the resistivity in NaFe 1-xCu xAs exhibits non-Fermi-liquid behavior near x≈1.8%. Our inelastic neutron scattering experiments reveal a single neutron spin resonance mode exhibiting weak dispersion along c axis inmore » NaFe 0.98Cu 0.02As. The resonance is high in energy relative to the superconducting transition temperature T c but weak in intensity, likely resulting from impurity effects. These results are similar to other iron pnictides superconductors despite that the superconducting phase in NaFe 1-xCu xAs is continuously connected to an antiferromagnetically ordered insulating phase near x≈50% with significant electronic correlations. Finally, therefore, electron correlations is an important ingredient of superconductivity in NaFe 1-xCu xAs and other iron pnictides.« less

Introducing a 2-His-1-Glu Nonheme Iron Center into Myoglobin Confers Nitric Oxide Reductase Activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Y.W.; Robinson, H.; Yeung, N.

2010-07-28

A conserved 2-His-1-Glu metal center, as found in natural nonheme iron-containing enzymes, was engineered into sperm whale myoglobin by replacing Leu29 and Phe43 with Glu and His, respectively (swMb L29E, F43H, H64, called Fe{sub B}Mb(-His)). A high resolution (1.65 {angstrom}) crystal structure of Cu(II)-CN?-Fe{sub B}Mb(-His) was determined, demonstrating that the unique 2-His-1-Glu metal center was successfully created within swMb. The Fe{sub B}Mb(-His) can bind Cu, Fe, or Zn ions, with both Cu(I)-Fe{sub B}Mb(-His) and Fe(II)-Fe{sub B}Mb(-His) exhibiting nitric oxide reductase (NOR) activities. Cu dependent NOR activity was significantly higher than that of Fe in the same metal binding site. EPRmore » studies showed that the reduction of NO to N{sub 2}O catalyzed by these two enzymes resulted in different intermediates; a five-coordinate heme-NO species was observed for Cu(I)-Fe{sub B}Mb(-His) due to the cleavage of the proximal heme Fe-His bond, while Fe(II)-Fe{sub B}Mb(-His) remained six-coordinate. Therefore, both the metal ligand, Glu29, and the metal itself, Cu or Fe, play crucial roles in NOR activity. This study presents a novel protein model of NOR and provides insights into a newly discovered member of the NOR family, gNOR.« less

Catalytic ozonation of petroleum refinery wastewater utilizing Mn-Fe-Cu/Al2O 3 catalyst.

PubMed

Chen, Chunmao; Yoza, Brandon A; Wang, Yandan; Wang, Ping; Li, Qing X; Guo, Shaohui; Yan, Guangxu

2015-04-01

There is of great interest to develop an economic and high-efficient catalytic ozonation system (COS) for the treatment of biologically refractory wastewaters. Applications of COS require options of commercially feasible catalysts. Experiments in the present study were designed to prepare and investigate a novel manganese-iron-copper oxide-supported alumina-assisted COS (Mn-Fe-Cu/Al2O3-COS) for the pretreatment of petroleum refinery wastewater. The highly dispersed composite metal oxides on the catalyst surface greatly promoted the performance of catalytic ozonation. Hydroxyl radical mediated oxidation is a dominant reaction in Mn-Fe-Cu/Al2O3-COS. Mn-Fe-Cu/Al2O3-COS enhanced COD removal by 32.7% compared with a single ozonation system and by 8-16% compared with Mn-Fe/Al2O3-COS, Mn-Cu/Al2O3-COS, and Fe-Cu/Al2O3-COS. The O/C and H/C ratios of oxygen-containing polar compounds significantly increased after catalytic ozonation, and the biodegradability of petroleum refinery wastewater was significantly improved. This study illustrates potential applications of Mn-Fe-Cu/Al2O3-COS for pretreatment of biologically refractory wastewaters.

Characteristics of Catalytic Gasification of Natural Coke with H2O in a Fluidized Bed

NASA Astrophysics Data System (ADS)

Lin, L. S.; Zhao, C. S.; Wang, S.; Zhu, G.; Xiang, W. G.

The experimental investigation on gasification characteristics of natural coke from Peicheng, Jiangsu with steam were conducted in a fluidized bed gasifier setup. The effects of several parameters, in terms of the catalyst type, the catalyst mixed manner and the dosage of catalyst over coke on the yield, the components, the heating value of fuel gas and the carbon conversion rate were examined. Results indicate that the fluidized bed gasification technology could overcome the shortcomings of natural coke. Ca-, Fe- and Cu-based nitrates could improve the gasification reaction effectively with a little difference, they could be listed in a descending sequence as follows: Cu-based>Fe-based>Ca-based according to their catalytic effect. The influences of Fe/Ca ratio and Cu/Ca ratio on gasification are similar, gas yield, carbon conversion rate and gas heating value per hour increase as Fe/Ca ratio or Cu/Ca ratio increases, but all of them go up first and then drop with decrease in Fe/Cu ratio. When the dosage of Ca-, Fe- and Cu-based nitrates mixed with the ratio of Ca/Fe/Cu= 10/35/55 is 3%, the best catalytic effect is achieved.

Charge dynamics of 57Fe probe atoms in La2Li0.5Cu0.5O4

NASA Astrophysics Data System (ADS)

Presniakov, I. A.; Sobolev, A. V.; Rusakov, V. S.; Moskvin, A. S.; Baranov, A. V.

2018-06-01

The objective of this study is to characterize the electronic state and local surrounding of 57Fe Mössbauer probe atoms within iron-doped layered perovskite La2Li0.5Cu0.5O4 containing transition metal in unusual formal oxidation states "+3". An approach based on the qualitative energy diagrams analysis and the calculations within the cluster configuration interaction method have been developed. It was shown that a large amount of charge is transferred via Cu-O bonds from the O: 2p bands to the Cu: 3d orbitals and the ground state is dominated by the d9L configuration ("Cu2+-O-" state). The dominant d9L ground state for the (CuO6) sublattice induces in the environment of the 57Fe probe cations a charge transfer Fe3+ + O-(L) → Fe4+ + O2-, which transforms "Fe3+" into "Fe4+" state. The experimental spectra in the entire temperature range 77-300 K were described with the use of the stochastic two-level model based on the assumption of dynamic equilibrium between two Fe3+↔Fe4+ valence states related to the iron atom in the [Fe(1)O4]4- center. The relaxation frequencies and activation energies of the corresponding charge fluctuations were estimated based on Mössbauer data. The results are discussed assuming a temperature-induced change in the electronic state of the [CuO4]5- clusters in the layered perovskite.

Evidence of cross-cutting and redox reaction in Khatyrka meteorite reveals metallic-Al minerals formed in outer space.

PubMed

Lin, Chaney; Hollister, Lincoln S; MacPherson, Glenn J; Bindi, Luca; Ma, Chi; Andronicos, Christopher L; Steinhardt, Paul J

2017-05-09

We report on a fragment of the quasicrystal-bearing CV3 carbonaceous chondrite Khatyrka recovered from fine-grained, clay-rich sediments in the Koryak Mountains, Chukotka (Russia). We show higher melting-point silicate glass cross-cutting lower melting-point Al-Cu-Fe alloys, as well as unambiguous evidence of a reduction-oxidation reaction history between Al-Cu-Fe alloys and silicate melt. The redox reactions involve reduction of FeO and SiO 2 to Fe and Fe-Si metal, and oxidation of metallic Al to Al 2 O 3 , occurring where silicate melt was in contact with Al-Cu-Fe alloys. In the reaction zone, there are metallic Fe and Fe-Si beads, aluminous spinel rinds on the Al-Cu-Fe alloys, and Al 2 O 3 enrichment in the silicate melt surrounding the alloys. From this and other evidence, we demonstrate that Khatyrka must have experienced at least two distinct events: first, an event as early as 4.564 Ga in which the first Al-Cu-Fe alloys formed; and, second, a more recent impact-induced shock in space that led to transformations of and reactions between the alloys and the meteorite matrix. The new evidence firmly establishes that the Al-Cu-Fe alloys (including quasicrystals) formed in outer space in a complex, multi-stage process.

The role of impurity ions in the formation of phase composition of Norilsk ore types

NASA Astrophysics Data System (ADS)

Mashukov, Anatoly; Mashukova, Alla

2013-04-01

Using the methods of X-ray and Mössbauer spectroscopy, scanning electron microscopy, there were studied the samples of Norilsk ore types in order to identify compounds containing Cu and Ni. Depending on elemental composition there were singled out two sample series. Maximum concentration in percentage of selected elements for this series is presented below. 1: Ni (0), Cu (0,42), S (11,2), O (20,2), H (0.02), Fe(46,8), Ca (5,85), Mg (1,75), K (0,47), Na (0). 2: Ni (4,93), Cu (0), S (14,9), O (27,1), H (0,11), Fe (28,1), Ca (14,9), Mg (0), K (0), Na (1,61). The research conducted by using the method of scanning electron microscopy and the X-ray microanalysis showed that iron and sulfur are spread uniformly over the scanned area. Sulfur is absent in the inclusions containing Fe and Ni. There are areas, sizes 8 - 120 microns, strongly enriched by Fe. The inclusions of rectangular and rhomboid shapes sizes 8 - 15 microns contain Ni as the content of Fe increases. There were identified the inclusions having a high content of Cu, with a maximum concentration of Ni. The presence of native elements testifies to the reducing mode of ore formation processes. The phases, containing Cu ? Ni, have a complex composition: pentlandite (FeNiS2), chalcopyrite (CuFeS2), bornite (CuFeS4), nickelhexahydrite (NiSO4 [6H2O]), wroewolfeite (Cu4 (OH) 6 (SO4) • 2H2O), pyrrhotine (Fe7S8), pyrite (FeS2). The position of the absorption lines in the magnetically ordered areas indicates the presence of stoichiometric FeS and CuFeS2. Some of the samples of this group have broadened lines, indicating the existence of various positions of the Fe ions in the sublattices. The ingrowths of CuFeS2 are characterized by the degree of the structure defectiveness, by various impurities, which is reflected in the studied parameters. As regards the other sample series, containing FeS and CuFeS2 in pyrrhotine matrix of Fe 1-xSx, the spectra are the superposition of the unsolved doublet, which shows the presence of paramagnetic areas. The magnetic phase has the spectrum composed of two six-linear spectrums. The peaks on the spectrum borders show the oxide presence. The isomer shifts of the samples range from 0 to 1.394 mm/s, quadrupole splitting ranges from 0 to 2.688 mm/s. This indicates that the local electronic structure depends on the genesis of compounds. Thus, most of the bulk of Cu, Ni is not dissipated in the crystal lattices of the ore, but it is part of the ore sulphides. The presence of the characteristic structures of the solid solutions decomposition shows a wide temperature range of sulphide crystallization.

Fabrication of Fe{sub 3}O{sub 4}@CuO core-shell from MOF based materials and its antibacterial activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajabi, S.K.; Sohrabnezhad, Sh., E-mail: sohrabnezhad@guilan.ac.ir; Ghafourian, S.

Magnetic Fe{sub 3}O{sub 4}@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe{sub 3}O{sub 4}@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe{sub 3}O{sub 4} core and a CuO shell. The Fe{sub 3}O{sub 4}@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe{sub 3}O{sub 4}-CuO core-shell was investigated againstmore » gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent. - Graphical abstract: Fe{sub 3}O{sub 4}@CuO core-shell release of copper ions. These Cu{sup 2+} ions were responsible for the exhibited antibacterial activity. - Highlights: • The Fe{sub 3}O{sub 4}@CuO core-shell was prepared by MOF method. • This is the first study of antibacterial activity of core-shell consist of CuO and Fe{sub 3}O{sub 4}. • The core-shell can be reused effectively. • Core-shell was separated from the reaction solution by external magnetic field.« less

Preparation and characterization of the magnetic superconductor EuSr2RuCu2O8-δ (RuEu-1212) by partial melting

NASA Astrophysics Data System (ADS)

Yamaki, K.; Kitagawa, N.; Funahashi, S.; Bamba, Y.; Irie, A.

2018-07-01

In this study, fine single crystals of the magnetic superconductor EuSr2RuCu2O8-δ (RuEu-1212) were successfully prepared using the partial melting technique. The obtained single crystals had a cubic shape, which coincides with the results of previous studies of RuGd-1212 single crystals. The single crystals had a typical length of 20-30 μm and the diffraction pattern observed from a sample prepared by partial melting was consistent with patterns of previously reported polycrystalline RuEu-1212 samples. A sample subjected to prolonged sintering, which consisted of a large number of combined micro single crystals prepared by partial melting, exhibited a superconducting transition with Tc-onset of 30.9 K and Tc-zero of 10.5 K.

Environmental application of millimeter-scale sponge iron (s-Fe(0)) particles (II): the effect of surface copper.

PubMed

Ju, Yongming; Liu, Xiaowen; Liu, Runlong; Li, Guohua; Wang, Xiaoyan; Yang, Yanyan; Wei, Dongyang; Fang, Jiande; Dionysiou, Dionysios D

2015-04-28

To enhance the catalytic reactivity of millimeter-scale particles of sponge iron (s-Fe(0)), Cu(2+) ions were deposited on the surface of s-Fe(0) using a simple direct reduction reaction, and the catalytic properties of the bimetallic system was tested for removal of rhodamine B (RhB) from an aqueous solution. The influence of Cu(0) loading, catalyst dosage, particle size, initial RhB concentration, and initial pH were investigated, and the recyclability of the catalyst was also assessed. The results demonstrate that the 3∼5 millimeter s-Fe(0) particles (s-Fe(0)(3∼5mm)) with 5wt% Cu loading gave the best results. The removal of RhB followed two-step, pseudo-first-order reaction kinetics. Cu(0)-s-Fe(0) showed excellent stability after five reuse cycles. Cu(0)-s-Fe(0) possesses great advantages compared to nanoscale zero-valent iron, iron power, and iron flakes as well as its bimetals. The surface Cu(0) apparently catalyzes the production of reactive hydrogen atoms for indirect reaction and generates Fe-Cu galvanic cells that enhance electron transfer for direct reaction. This bimetallic catalyst shows great potential for the pre-treatment of recalcitrant wastewaters. Additionally, some oxides containing iron element are selected to simulate the adsorption process. The results prove that the adsorption process of FeOOH, Fe2O3 and Fe3O4 played minor role for the removal of RhB. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis, spectroscopy, and binding constants of ketocatechol-containing iminodiacetic acid and its Fe(III), Cu(II), and Zn(II) complexes and reaction of Cu(II) complex with H₂O₂ in aqueous solution.

PubMed

Gao, Jiaojiao; Xing, Feifei; Bai, Yueling; Zhu, Shourong

2014-06-07

A new neuromelanin-like ketocatechol-containing iminodiacetic acid ligand, (N-(3,4-dihydroxyl)phenacylimino)diacetic acid (H4L), which is also quite similar to compounds found in insect cuticle, has been synthesized and characterized. The X-ray crystal structure of H4L has been successfully determined. Proton binding and coordination with Fe(III), Cu(II), and Zn(II) have been studied by potentiometric titrations and UV-vis spectrophotometry in aqueous solution. UV spectra of H4L in the absence and presence of different metal ions indicate complexes formed with the catechol moiety of H4L in aqueous solution. Visible spectra and NMR reveal that H4L with Fe(III), Cu(II), and Zn(II) can all give stable mono-(ML) and dinuclear complexes [M(ML)]. Fe(III) can also form {Fe(FeL)2} and {Fe(FeL)3} species with sufficient base. The process is accompanied by a drastic color change from light blue to deep-blue to wine-red. The Fe(III)-Cu(II) heteronuclear complex also exists in aqueous solution whose spectra are similar to the homonuclear Fe(III) complex. However, the spectra of {Fe(CuL)} shifted to a longer wavelength and {Fe(CuL)2} and {Fe(CuL)3} shifted to a shorter wavelength. Keto-enol tautomerism was observed in weak basic aqueous solution as indicated by (1)H NMR spectra. The reaction products of Cu(II) complex with H2O2 depend on the H2O2 concentration and pH value. Low concentrations of H2O2 oxidize H4L to a series of semiquinone and quinone compounds with absorption maxima at 314-400 nm, while a high concentration of H2O2 oxidizes H4L to colorless muconic acid derivatives. NaIO4 gives different oxidase products, but no 2,4,5-trihydroxyphenylalanine quinone (TPQ)-like hydroxyquinone can be found.

Copper-tuned magnetic order and excitations in iron-based superconductors Fe1+yTe1-xSex

NASA Astrophysics Data System (ADS)

Wen, Jinsheng; Xu, Zhijun; Xu, Guangyong; Lumsden, Mark; Matsuda, Masaaki; Valdivia, Patrick; Bourret, Edith; Lee, Dunghai; Gu, Genda; Tranquada, John; Birgeneau, Robert

2012-02-01

We report neutron scattering results on the Cu-substitution effects in the iron-based superconductors, Fe1+yTe1-xSex. In the parent compound, it is found that Cu drives the low-temperature magnetic ground state from long-range commensurate antiferromagnetic order in Fe1.06TeCu0.04 to short-range incommensurate order in FeTeCu0.1. In the former sample, the structural and magnetic ordering temperature is 40 K; in FeTeCu0.1, the structural phase transition is not obvious and a transition to the spin-glass state is found at 22 K. Cu suppresses superconductivity in FeTe0.5Se0.5---Tc is reduced to 7 K with a 2% Cu doping, and no superconductivity is found in the 10% Cu-doped sample. In the meantime, the intensity and energy of the resonance mode are suppressed in the 2% Cu-doped sample, while there is no resonance in the non-superconducting sample. Besides, the low-temperature magnetic excitation spectra are distinct for these two samples, with the superconducting one having an ``hour-glass" shape and the other one having a ``waterfall" shape. Our results provide further insights on the interplay between magnetism and superconductivity in the iron-based superconductors.

Catalytic conversion of syngas to mixed alcohols over Zn-Mn promoted Cu-Fe based catalyst

DOE PAGES

Lu, Yongwu; Yu, Fei; Hu, Jin; ...

2012-04-12

Zn-Mn promoted Cu-Fe based catalyst was synthesized by the co-precipitation method. Mixed alcohols synthesis from syngas was studied in a half-inch tubular reactor system after the catalyst was reduced. Zn-Mn promoted Cu-Fe based catalyst was characterized by SEM-EDS, TEM, XRD, and XPS. The liquid phase products (alcohol phase and hydrocarbon phase) were analyzed by GC-MS and the gas phase products were analyzed by GC. The results showed that Zn-Mn promoted Cu-Fe based catalyst had high catalytic activity and high alcohol selectivity. The maximal CO conversion rate was 72%, and the yield of alcohol and hydrocarbons were also very high. Cumore » (111) was the active site for mixed alcohols synthesis, Fe 2C (101) was the active site for olefin and paraffin synthesis. The reaction mechanism of mixed alcohols synthesis from syngas over Zn-Mn promoted Cu-Fe based catalyst was proposed. Here, Zn-Mn promoted Cu-Fe based catalyst can be regarded as a potential candidate for catalytic conversion of biomass-derived syngas to mixed alcohols.« less

Luminescence and magnetic properties of novel nanoparticle-sheathed 3D Micro-Architectures of Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) for bifunctional application

NASA Astrophysics Data System (ADS)

Krishnan, Rajagopalan; Thirumalai, Jagannathan; Kathiravan, Arunkumar

2015-01-01

For the first time, we report the successful synthesis of novel nanoparticle-sheathed bipyramid-like and almond-like Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) 3D hierarchical microstructures through a simple disodium ethylenediaminetetraacetic acid (Na2EDTA) facilitated hydrothermal method. Interestingly, time-dependent experiments confirm that the assembly-disassembly process is responsible for the formation of self-aggregated 3D architectures via Ostwald ripening phenomena. The resultant products are characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and magnetic measurements. The growth and formation mechanisms of the self-assembled 3D micro structures are discussed in detail. To confirm the presence of all the elements in the microstructure, the energy loss induced by the K, L shell electron ionization is observed in order to map the Fe, Gd, Mo, O, and Eu components. The photo luminescence properties of Fe0.5R0.5(MoO4)1.5 doped with Eu3+, Tb3+, Dy3+ are investigated. The room temperature and low temperature magnetic properties suggest that the interaction between the local-fields introduced by the magnetic Fe3+ ions and the R3+ (La, Gd) ions in the dodecahedral sites determine the magnetism in Fe0.5R0.5(MoO4)1.5:Eu3+. This work provides a new approach to synthesizing the novel Fe0.5R0.5(MoO4)1.5:Ln3+ for bi-functional magnetic and luminescence applications.

Fabrication and photocatalytic property of magnetic NiFe2O4/Cu2O composites

NASA Astrophysics Data System (ADS)

He, Zuming; Xia, Yongmei; Tang, Bin; Su, Jiangbin

2017-09-01

Magnetically separable NiFe2O4/Cu2O composites were successfully synthesized by a two-step method. The samples were characterized by XRD, XPS, SEM and VSM as well as their PL spectra and UV-vis adsorption spectra. The results showed that the NiFe2O4/Cu2O composites were composed of cubic-structured Cu2O and spinel-structured NiFe2O4, were able to absorb a large amount of visible light, exhibited excellent photocatalytic activity under simulated solar light irradiation and could be easily separated by an external magnetic field. The NiFe2O4/Cu2O composites exhibited higher photocatalytic performance than that of a single semiconductor. It was found that the prominently enhanced photocatalytic performance of NiFe2O4/Cu2O composites was ascribed to the effective separation of photo-generated electron-hole pairs and the effective generation of the hydroxyl radical •OH.

Structural, electronic, and elastic properties of CuFeS2: first-principles study

NASA Astrophysics Data System (ADS)

Zhou, Meng; Gao, Xiang; Cheng, Yan; Chen, Xiangrong; Cai, Lingcang

2015-03-01

The structural, electronic, and elastic properties of CuFeS2 have been investigated by using the generalized gradient approximation (GGA), GGA + U (on-site Coulomb repulsion energy), the local density approximation (LDA), and the LDA + U approach in the frame of density functional theory. It is shown that when the GGA + U formalism is selected with a U value of 3 eV for the 3d state of Fe, the calculated lattice constants agree well with the available experimental and other theoretical data. Our GGA + U calculations indicate that CuFeS2 is a semiconductor with a band gap of 0.552 eV and with a magnetic moment of 3.64 µB per Fe atom, which are well consistent with the experimental results. Combined with the density of states, the band structure characteristics of CuFeS2 have been analyzed and their origins have been specified, which reveals a hybridization existing between Fe-3d, Cu-3s, and S-3p, respectively. The charge and Mulliken population analyses indicate that CuFeS2 is a covalent crystal. Moreover, the calculated elastic constants prove that CuFeS2 is mechanically stable but anisotropic. The bulk modulus obtained from elastic constants is 87.1 GPa, which agrees well with the experimental value of 91 ± 15 GPa and better than the theoretical bulk modulus 74 GPa obtained from GGA method by Lazewski et al. The obtained shear modulus and Debye temperature are 21.0 GPa and 287 K, respectively, and the latter accords well with the available experimental value. It is expected that our work can provide useful information to further investigate CuFeS2 from both the experimental and theoretical sides.

Enhanced thermal stability of Cu alloy films by strong interaction between Ni and Zr (or Fe)

NASA Astrophysics Data System (ADS)

Zheng, Yuehong; Li, Xiaona; Cheng, Xiaotian; Li, Zhuming; Liu, Yubo; Dong, Chuang

2018-04-01

Low resistivity, phase stability and nonreactivity with surrounding dielectrics are the key to the application of Cu to ultra-large-scale integrated circuits. Here, a stable solid solution cluster model was introduced to design the composition of barrierless Cu-Ni-Zr (or Fe) seed layers. The third elements Fe and Zr were dissolved into Cu via a second element Ni, which is soluble in both Cu and Zr (or Fe). The films were prepared by magnetron sputtering on the single-crystal p-Si (1 0 0) wafers. Since the diffusion characteristics of the alloying elements are different, the effects of the strong interaction between Ni and Zr (or Fe) on the film’s stability and resistivity were studied. The results showed that a proper addition of Zr-Ni (Zr/Ni  ⩽  0.6/12) into Cu could form a large negative lattice distortion, which inhibits Cu-Si interdiffusion and enhances the stability of Cu film. When Fe-Ni was co-added into Cu, the lattice distortion of Cu reached a lower value, 0.0029 Å  ⩽  |Δa|  ⩽  0.0046 Å, and the films showed poor stability. Therefore, when the model is applied to the composition design of the films, the strong interaction between the elements and the addition ratio should be taken into consideration.

Facile synthesis, characterization and magnetic property of CuFe12O19 nanostructures via a sol-gel auto-combustion process

NASA Astrophysics Data System (ADS)

Ansari, Fatemeh; Sobhani, Azam; Salavati-Niasari, Masoud

2016-03-01

Copper hexaferrite (CuFe12O19) nanostructures were prepared by a simple route utilizing maltose-assisted sol-gel process. The morphology, phase structure, composition and purity of nanostructures can be controlled by type of surfactant and also adjusting the Cu:surfactant, Cu:Fe and Cu:reductant ratios. The bean-shape structures are formed in the absence of the surfactant when the molar ratio of Cu:Fe and Cu:reductant are 1:12 and 1:26, respectively. The agglomerated spherical nanoparticles with diameters ranging from 7 to 20 nm are obtained in the presence of triplex, when ratio of Cu:reductant is 1:26. In the absence of surfactant and also in the presence of triplex, the samples are found to be CuFe12O19. When polymer is used, there are still the peaks of CuFe12O19 and also some boad peaks in XRD patterns, because of the small size and encapsulation of nanostructures with polymer. Magnetic measurments show superparamagnetic behavior for the all samples. The Ms for the samples obtained in the presence of polymer shows that the coating of magnetic nanostructures does not always increase Ms. FT-IR frequency bands in the range 463-626, 607 and 542 cm-1 correspond to the formation of metal oxides in ferrites.

Development of Long REBCO with BMO Coated Conductors by PLD Method with High Production Rate

NASA Astrophysics Data System (ADS)

Ibi, A.; Yoshida, T.; Taneda, T.; Yoshizumi, M.; Izumi, T.; Shiohara, Y.

We have been developing long REBa2Cu3O7-δ (RE: Y, Gd and Eu etc.) with BaMO3 (M: Zr, Sn and Hf etc.) coated conductors by the combination of the ion-beam assisted deposition (IBAD) and the pulsed laser deposition (PLD) methods. REBa2Cu3O7-δ with BaMO3 coated conductors showed high in-field performance, therefore, these coated conductors could be expected for the industrial and commercial applications at high temperatures in magnetic fields. However, to realize the low production cost for long REBa2Cu3O7-δ with BaMO3 coated conductors, improvement of the production rate of the REBa2Cu3O7-δ layers containing BaMO3 rods with maintaining high superconducting properties is required. To solve these problems, we have tried deposition of the REBa2Cu3O7-δ layers with high superconducting properties by the PLD method with high production rate. As a result, we have successfully fabricated EuBa2Cu3O7-δ layers containing BaHfO3 rods with high in-field Jc and Ic by the PLD method with high production rate. This EuBa2Cu3O7-δ with BaHfO3 coated conductor exhibit a high Ic value of 412 and 48.7 A/cm-width at 77 K in self-field and 3 T, respectively at the deposition rate of about 40 μm/h and the production rate of 10 m/h for a 1.35 μm EuBCO layer thick.

Influence of trace elements mixture on bacterial diversity and fermentation characteristics of liquid diet fermented with probiotics under air-tight condition.

PubMed

He, Yuyong; Chen, Zhiyu; Liu, Xiaolan; Wang, Chengwei; Lu, Wei

2014-01-01

Cu2+, Zn2+, Fe2+ and I- are often supplemented to the diet of suckling and early weaning piglets, but little information is available regarding the effects of different Cu2+, Zn2+, Fe2+ and I- mixtures on bacteria growth, diversity and fermentation characteristics of fermented liquid diet for piglets. Pyrosequencing was performed to investigate the effect of Cu2+, Zn2+, Fe2+ and I- mixtures on the diversity, growth and fermentation characteristics of bacteria in the liquid diet fermented with Bacillus subtilis and Enterococcus faecalis under air-tight condition. Results showed that the mixtures of Cu2+, Zn2+, Fe2+ and I- at different concentrations promoted Bacillus growth, increased bacterial diversity and lactic acid production and lowered pH to about 5. The importance of Cu2+, Zn2+, Fe2+ and I- is different for Bacillus growth with the order Zn2+> Fe2+>Cu2+> I- in a 21-d fermentation and Cu2+>I->Fe2+>Zn2+ in a 42-d fermentation. Cu2+, Zn2+, Fe2+ and I- is recommended at a level of 150, 60, 150 and 0.6 mg/kg respectively for the production of fermented liquid diet with Bacillus subtilis. The findings improve our understanding of the influence of trace elements on liquid diet fermentation with probiotics and support the proper use of trace elements in the production of fermented liquid diet for piglets.

Magnetization reversal process and evaluation of thermal stability factor in Cu doped granular L10 FePt films

NASA Astrophysics Data System (ADS)

Jain, S.; Papusoi, C.; Admana, R.; Yuan, H.; Acharya, R.

2018-05-01

Curie temperature TC distributions and magnetization reversal mechanism in Cu doped L10 FePt granular films is investigated as a function of film thickness in the range of ˜5-12 nm with Cu mol. % varying in the range of 0%-6%. It is shown that Cu doping increases the FePt tetragonality and chemical ordering. For Cu doped FePt-X films, coercivity (HC) exhibits a non-monotonic behavior with increasing film thickness, i.e., HC increases initially up to tcr ˜ 7 nm, and decreases thereafter. We attribute this behavior to the change in magnetization reversal mechanism from coherent to an incoherent (domain-wall driven) mode. While in un-doped films, the domain-walls nucleate at the grain boundaries, in doped films the Cu atoms may act as domain-wall nucleation and pinning sites, isolating magnetic spin clusters of reduced dimensionality with respect to the physical grain size. This is experimentally supported by a much poorer dependence of the AC susceptibility (both, real and imaginary components) on the film thickness above 7 nm than in the case of un-doped films. The formation of magnetic spin clusters inside the grains as a consequence of the reduced coupling between Fe-Fe and Fe-Pt-Fe atoms with increasing Cu doping can explain the experimentally evidenced reduction of both, the film Curie temperature, TC, and intrinsic anisotropy energy density, KC, with increasing Cu doping.

Possibility to Use Hydrothermally Synthesized CuFeS2 Nanocomposite as an Acceptor in Hybrid Solar Cell

NASA Astrophysics Data System (ADS)

Sil, Sayantan; Dey, Arka; Halder, Soumi; Datta, Joydeep; Ray, Partha Pratim

2018-01-01

Here we have approached the plausible use of CuFeS2 nanocomposite as an acceptor in organic-inorganic hybrid solar cell. To produce CuFeS2 nanocomposite, hydrothermal strategy was employed. The room-temperature XRD pattern approves the synthesized material as CuFeS2 with no phase impurity (JCPDS Card no: 37-0471). The elemental composition of the material was analyzed from the TEM-EDX data. The obtained selected area electron diffraction (SAED) planes harmonized with the XRD pattern of the synthesized product. Optical band gap (4.14 eV) of the composite from UV-Vis analysis depicts that the synthesized material is belonging to wide band gap semiconductor family. The HOMO (- 6.97 eV) and LUMO (- 2.93 eV) positions from electrochemical study reveal that there is a possibility of electron transfer from MEH-PPV to CuFeS2. The optical absorption and photoluminescence spectra of MEH-PPV:CuFeS2 (donor:acceptor) composite were recorded sequentially by varying weight ratios. The monotonic blue shifting of the absorption peak position indicated the interaction between donor and acceptor materials. The possibility of electron transfer from donor (MEH-PPV) to acceptor (CuFeS2) was approved with photoluminescence analysis. Subsequently, we have fabricated a hybrid solar cell by incorporating CuFeS2 nanocomposite with MEH-PPV in open atmosphere and obtained 0.3% power conversion efficiency.

Dye-Sensitized Cu2 XSnS4 (X=Zn, Ni, Fe, Co, and Mn) Nanofibers for Efficient Photocatalytic Hydrogen Evolution.

PubMed

Gonce, Mehmet Kerem; Aslan, Emre; Ozel, Faruk; Hatay Patir, Imren

2016-03-21

The photocatalytic hydrogen evolution activities of low-cost and noble-metal-free Cu2 XSnS4 (X=Zn, Ni, Fe, Co, and Mn) nanofiber catalysts have been investigated using triethanolamine as an electron donor and eosin Y as a photosensitizer under visible-light irradiation. The rates of hydrogen evolution by Cu2 XSnS4 (X=Zn, Ni, Fe, Co, and Mn) nanofibers have been compared with each other and with that of the noble metal Pt. The hydrogen evolution rates for the nanofibers change in the order Cu2 NiSnS4 >Cu2 FeSnS4 >Cu2 CoSnS4 >Cu2 ZnSnS4 >Cu2 MnSnS4 (2028, 1870, 1926, 1420, and 389 μmol g(-1) h(-1) , respectively). The differences between the hydrogen evolution rates of the nanofibers could be attributed to their energy levels. Moreover, Cu2 NiSnS4, Cu2 FeSnS4 , and Cu2 CoSnS4 nanofibers show higher and more stable photocatalytic hydrogen production rates than that of the noble metal Pt under long-term irradiation with visible light. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High resolution positron annihilation induced Auger electron spectroscopy of the CuM 2,3VV-transition and of Cu sub-monolayers on Pd and Fe

NASA Astrophysics Data System (ADS)

Mayer, J.; Hugenschmidt, C.; Schreckenbach, K.

2010-09-01

We present a high resolution positron annihilation induced Auger Electron Spectroscopy (PAES) of the CuM 2,3VV-transition with the unprecedented energy resolution of Δ/EE <1%. This energy resolution and the highly intense positron source NEPOMUC enabled us to resolve the double peak structure with PAES for the first time within a measurement time of only 5.5 h. In addition, sub-monolayers of Cu were deposited on Fe- and Pd-samples in order to investigate the surface selectivity of PAES in comparison with EAES. The extremely high surface selectivity of PAES due to the different positron affinity of Cu and Fe lead to the result that with only 0.96 monolayer of Cu on Fe more than 55% of the emitted Auger electrons stem from Cu, whereas with EAES the Cu Auger fraction amounted to less than 6%.

Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil

NASA Astrophysics Data System (ADS)

Dong, Honggang; Yang, Zhonglin; Wang, Zengrui; Deng, Dewei; Dong, Chuang

2014-10-01

Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

Coating magnetic CuFe2O4 nanoparticles with OMS-2 for enhanced degradation of organic pollutants via peroxymonosulfate activation

NASA Astrophysics Data System (ADS)

Ye, Peng; Wu, Deming; Wang, Manye; Wei, Yi; Xu, Aihua; Li, Xiaoxia

2018-01-01

A heterogeneous magnetic CuFe2O4@OMS-2 catalyst was fabricated through a facile solvent-free process using Mn(CH3COO)2 and KMnO4 in the presence of CuFe2O4. It was found that the BET surface area of OMS-2 as well as the ratio of low-valent manganese species significantly increased in the hybrid catalyst, due to interactions between CuFe2O4 and the precursor of amorphous manganese oxide. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the CuFe2O4@OMS-2 catalyst within 30 min in the presence of peroxymonosulfate (PMS), while CuFe2O4 and OMS-2 showed no significant activity for the reaction. The hybrid catalyst also exhibited excellent long-term stability and could be easily recovered with the assistance of an external magnetic field. A possible degradation mechanism for the synergistic effects of different valent metal species and reactive radicals was proposed, which involved the electron transfer from Mn(III) or Mn(II) species to PMS with the generation of sulfate and hydroxyl radicals, and from AO7 and Cu(I) in CuFe2O4 to Mn(IV) and Mn(III) to reduce these Mn species.

Introducing a 2-His-1-Glu Nonheme Iron Center into Myoglobin Confers Nitric Oxide Reductase Activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Y Lin; N Yeung; Y Gao

2011-12-31

A conserved 2-His-1-Glu metal center, as found in natural nonheme iron-containing enzymes, was engineered into sperm whale myoglobin by replacing Leu29 and Phe43 with Glu and His, respectively (swMb L29E, F43H, H64, called Fe{sub B}Mb(-His)). A high resolution (1.65 {angstrom}) crystal structure of Cu(II)-CN{sup -}-Fe{sub B}Mb(-His) was determined, demonstrating that the unique 2-His-1-Glu metal center was successfully created within swMb. The Fe{sub B}Mb(-His) can bind Cu, Fe, or Zn ions, with both Cu(I)-Fe{sub B}Mb(-His) and Fe(II)-Fe{sub B}Mb(-His) exhibiting nitric oxide reductase (NOR) activities. Cu dependent NOR activity was significantly higher than that of Fe in the same metal binding site.more » EPR studies showed that the reduction of NO to N{sub 2}O catalyzed by these two enzymes resulted in different intermediates; a five-coordinate heme-NO species was observed for Cu(I)-Fe{sub B}Mb(-His) due to the cleavage of the proximal heme Fe-His bond, while Fe(II)-Fe{sub B}Mb(-His) remained six-coordinate. Therefore, both the metal ligand, Glu29, and the metal itself, Cu or Fe, play crucial roles in NOR activity. This study presents a novel protein model of NOR and provides insights into a newly discovered member of the NOR family, gNOR.« less

Cu-Mn-Fe alloys and Mn-rich amphiboles in ancient copper slags from the Jabal Samran area, Saudi Arabia: With synopsis on chemistry of Fe-Mn(III) oxyhydroxides in alteration zones

NASA Astrophysics Data System (ADS)

Surour, Adel A.

2015-01-01

In the Jabal Samran area (western Saudi Arabia), secondary copper mineralization in a NE-trending shear zone in which the arc metavolcanic host rocks (dacite-rhyodacite) show conjugate fractures and extensive hydrothermal alteration and bleaching. The zones contain frequent Fe-Mn(III) oxyhydroxides (FeOH-MnOH) that resulted from oxidation of pyrite and Mn-bearing silicates. In the bleached part, the groundmass is represented by Fe-bearing interstratified illite-smectite with up to 4.02 wt% FeOt. FeOH-MnOH are pre-weathering phases formed by hydrothermal alteration in a submarine environment prior to uplifting. Five varieties of FeOH are distinguished, four of them are exclusively hydrothermal with ∼20 wt% H2O whereas the fifth contains ∼31-33 wt% H2O and might represent reworking of earlier hydrothermal FeOH phases by weathering. FeOH fills thin fractures in the form of veinlets and crenulated laminae or as a pseudomorph for pyrite, goethite and finally ferrihydrite, and this oxyhydroxide is characterized by positive correlation of Fe2O3 with SiO2 and Al2O3. On the other hand, MOH shows positive correlation between MnO2 and Al2O3 whereas it is negative between Fe2O3 and SiO2. Paratacamite is the most common secondary copper mineral that fills fractures and post-dates FeOH and MnOH. It is believed that Cl- in the structure of paratacamite represents inherited marine storage rather than from surfacial evaporates or meteoric water. The mineralogy of slags suggests a complicated mineral assemblage that includes native Cu prills, synthetic spinifixed Mn-rich amphiboles with 16.73 wt% MnO, brown glass and Ca-Mn-Fe phase close to the olivine structure. EMPA indicate that the some Cu prills have either grey discontinuous boarder zone of S-rich Mn-Cu alloy (with up to 21.95 wt% S and 19.45 wt% Mn) or grey Cu-Mn-Fe alloy (with up to 15.9 wt% Cu, 39. 12 wt% Mn and 61.64 wt% Fe). Mn in the Cu prills is expelled inward as Cu-Mn-Fe alloy inclusions whereas S is expelled outward as S-rich Mn-Cu alloy crust. Remains in the Samran smelter sites suggest the use of charcoal as a source of energy, quartzite as a flux and an air-cooling technique was used.

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability.

PubMed

Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

2017-11-05

In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

PubMed Central

Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

2017-01-01

In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics. PMID:29113096

Kinetic phenomena in zero-gap semiconductors CuFeS2 and CuFeTe2: Effect of pressure and heat treatment

NASA Astrophysics Data System (ADS)

Popov, V. V.; Konstantinov, P. P.; Rud', Yu. V.

2011-10-01

Electrical resistivity ρ and Hal coefficient R are measured as a function of the temperature ( T = 1.7-310 K) and the magnetic field (up to H = 28 kOe) in zero-gap semiconductor CuFeS2 samples subjected to hydrostatic compression and under various heat-treatment conditions. At low temperatures, anomalies are observed in the kinetic effects related to the presence of ferromagnetic clusters: the magnetoresistance at T = 4.2 K and T = 20.4 K acquires a hysteretic character and thermopower α changes its sign at T < 15 K. The temperature dependence of conduction-electron concentration n in CuFeS2 has a power form in the temperature range T = 14-300 K, which is characteristic of the intrinsic conductivity in zero-gap semiconductors. In CuFeS2, we have n( T) ∝ T 1.2; in isoelectron compound Cu1.13Fe1.22Te2, we have n( T) ∝ T 1.93. Heat treatment is found to affect the intrinsic conductivity of CuFeS2, as the action of hydrostatic compression (carrier concentration changes); that is, the carrier concentration changes. However, a power form of the n( T) and ρ( T) dependences is retained.

Thermally promoted evolution of open-volume defects and Cu precipitates in the deformed FeCu alloys

NASA Astrophysics Data System (ADS)

Jin, Shuoxue; Cao, Xingzhong; Cheng, Guodong; Lian, Xiangyu; Zhu, Te; Zhang, Peng; Yu, Runsheng; Wang, Baoyi

2018-04-01

We have studied the effect of isothermal annealing on the evolution of the open-volume defect and the Cu precipitate in deformed Fe0.15Cu, Fe0.3Cu and Fe0.6Cu alloys. Using the coincidence Doppler broadening, positron annihilation lifetime and the S-W couples, the evolution of local electronic circumstance around the annihilation sites, open-volume defects and interaction between open-volume defects and Cu precipitates were measured as a function of the isothermal annealing temperatures. Cold rolling deformation induced an obvious increment in S parameters due to the formation of open-volume defects. Annealing not only resulted in gradual recovery of open-volume defects and Cu thermal precipitation, but also promoted the combination and interaction between defects and Cu precipitates. The interaction between open-volume defects and Cu precipitates was revealed clearly by the view point of S-W relationship. The S-W interaction for the different CumVn complexes was also calculated theoretically by MIKA-Doppler, which supports our experimental observations qualitatively. The results indicate that open-volume defects were formed first after cold rolling, followed by the Cu precipitation and recovery of open-volume defects, Cu precipitates recovered at the end. It is interesting that the trajectory of (S, W) points with increasing annealing temperature formed a similar closed "Parallelogram" shape. It is benefit for revealing the behavior of Cu thermal precipitation and their evolution in various Cu-bearing steels under thermal treatment. In addition, we also investigated the Cu content effect on the Cu precipitation in FeCu alloys, and the Cu precipitate phenomenon was enhanced in higher Cu content alloys.

Fabrication and characterization of thin-film phosphor combinatorial libraries

NASA Astrophysics Data System (ADS)

Mordkovich, V. Z.; Jin, Zhengwu; Yamada, Y.; Fukumura, T.; Kawasaki, M.; Koinuma, H.

2002-05-01

The laser molecular beam epitaxy method was employed to fabricate thin-film combinatorial libraries of ZnO-based phosphors on different substrates. Fabrication of both pixel libraries, on the example of Fe-doped ZnO, and spread libraries, on the example of Eu-doped ZnO, has been demonstrated. Screening of the Fe-doped ZnO libraries led to the discovery of weak green cathodoluminescence with the maximum efficiency at the Fe content of 0.58 mol %. Screening of the Eu-doped ZnO libraries led to the discovery of unusual reddish-violet cathodoluminescence which is observed in a broad range of Eu concentration. No photoluminescence was registered in either system.

Testing Room-Temperature Ionic Liquid Solutions for Depot Repair of Aluminum Coatings

DTIC Science & Technology

2011-05-01

Ne 3 Na Mg IIIB IVB VB VIB VIIB ------ VIIIB ------ IB IIB Al Si P S Cl Ar 4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 5 Rb Sr Y Zr Nb Mo Tc...Ru Rh Pd Ag Cd In Sn Sb Te I Xe 6 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 7 Fr Ra Ac Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np...Electroplating Bath Lid Arrangement ;:::::::::::=== Thermometer Purge gas vent Anode lead Cathode lead (Extractable from the lid) Purge feed gas

Intermediate-valence state of the Sm and Eu in SmB6 and EuCu2Si2: neutron spectroscopy data and analysis

NASA Astrophysics Data System (ADS)

Savchenkov, P. S.; Alekseev, P. A.; Podlesnyak, A.; Kolesnikov, A. I.; Nemkovski, K. S.

2018-02-01

Magnetic neutron scattering data for Sm (SmB6, Sm(Y)S) and Eu (EuCu2Si2-x Ge x ) intermediate-valence compounds have been analysed in terms of a generalized model of the intermediate-radius exciton. Special attention is paid to the correlation between the average ion’s valence and parameters of the low-energy excitation in the neutron spectra, such as the resonance mode, including its magnetic form factor. Along with specific features of the formation of the intermediate-valence state for Sm and Eu ions, common physical mechanisms have been revealed for systems based on these elements from the middle of the rare-earth series. A consistent description of the existing experimental data has been obtained by using the concept of a loosely bound hole for the Eu f-electron shell in the intermediate-valence state, in analogy with the previously established loosely bound electron model for the Sm ion.

Dietary Intakes of Minerals, Essential and Toxic Trace Elements for Adults from Eragrostis tef L.: A Nutritional Assessment.

PubMed

Koubová, Eva; Sumczynski, Daniela; Šenkárová, Lenka; Orsavová, Jana; Fišera, Miroslav

2018-04-12

This study analysed the contents of thirty-six mineral and trace elements in teff ( Eragrostis tef L.) grains. What is more, dietary intakes were calculated. Inductively coupled plasma mass spectrometry (ICP-MS) was used to assess mineral and trace element contents. Consequently, the appropriate Recommended Dietary Allowance (RDA) or adequate intake (AI), and provisional tolerable weekly intake (PTWI) or provisional tolerable monthly intake (PTMI) values for adults were determined according to the Food and Agriculture Organization/World Health Organization (FAO/WHO) and Institute of Medicine (IOM) regulations. Teff is a significant contributor to RDAs and AIs for females in the following order: Mn > Cu > Zn ≥ Mg > Fe ≥ P and Ca. For males, teff contributes in the order, Mn > Cu > Fe > Zn ≥ P ≥ Mg > and Ca. The concentration of arsenic (65.9 µg/kg) in brown teff originating in Bolivia exceeded the average acceptable value set by Reg. No. 1881 of 6-50 µg/kg in cereals consumed in the EU. The PTWIs or PTMIs for Al, Cd, Sn and Hg were all under 7%, which is below the limits of toxic element intake related to the body weight of 65 kg for adult females and 80 kg for males, set by the FAO/WHO. Teff grains can be recommended as a valuable and safe source of minerals and trace elements.

Dietary Intakes of Minerals, Essential and Toxic Trace Elements for Adults from Eragrostis tef L.: A Nutritional Assessment

PubMed Central

Koubová, Eva; Šenkárová, Lenka

2018-01-01

This study analysed the contents of thirty-six mineral and trace elements in teff (Eragrostis tef L.) grains. What is more, dietary intakes were calculated. Inductively coupled plasma mass spectrometry (ICP-MS) was used to assess mineral and trace element contents. Consequently, the appropriate Recommended Dietary Allowance (RDA) or adequate intake (AI), and provisional tolerable weekly intake (PTWI) or provisional tolerable monthly intake (PTMI) values for adults were determined according to the Food and Agriculture Organization/World Health Organization (FAO/WHO) and Institute of Medicine (IOM) regulations. Teff is a significant contributor to RDAs and AIs for females in the following order: Mn > Cu > Zn ≥ Mg > Fe ≥ P and Ca. For males, teff contributes in the order, Mn > Cu > Fe > Zn ≥ P ≥ Mg > and Ca. The concentration of arsenic (65.9 µg/kg) in brown teff originating in Bolivia exceeded the average acceptable value set by Reg. No. 1881 of 6–50 µg/kg in cereals consumed in the EU. The PTWIs or PTMIs for Al, Cd, Sn and Hg were all under 7%, which is below the limits of toxic element intake related to the body weight of 65 kg for adult females and 80 kg for males, set by the FAO/WHO. Teff grains can be recommended as a valuable and safe source of minerals and trace elements. PMID:29649158

Chemical Abundances of Two Stars in the Large Magellanic Cloud Globular Cluster NGC 1718

NASA Astrophysics Data System (ADS)

Sakari, Charli M.; McWilliam, Andrew; Wallerstein, George

2017-05-01

Detailed chemical abundances of two stars in the intermediate-age Large Magellanic Cloud (LMC) globular cluster NGC 1718 are presented, based on high-resolution spectroscopic observations with the MIKE spectrograph. The detailed abundances confirm NGC 1718 to be a fairly metal-rich cluster, with an average [Fe/H] ˜ -0.55 ± 0.01. The two red giants appear to have primordial O, Na, Mg and Al abundances, with no convincing signs of a composition difference between the two stars - hence, based on these two stars, NGC 1718 shows no evidence for hosting multiple populations. The Mg abundance is lower than Milky Way field stars, but is similar to LMC field stars at the same metallicity. The previous claims of very low [Mg/Fe] in NGC 1718 are therefore not supported in this study. Other abundances (Si, Ca, Ti, V, Mn, Ni, Cu, Rb, Y, Zr, La and Eu) all follow the LMC field star trend, demonstrating yet again that (for most elements) globular clusters trace the abundances of their host galaxy's field stars. Similar to the field stars, NGC 1718 is found to be mildly deficient in explosive α-elements, but moderately to strongly deficient in O, Na, Mg, Al and Cu, elements that form during hydrostatic burning in massive stars. NGC 1718 is also enhanced in La, suggesting that it was enriched in ejecta from metal-poor asymptotic giant branch stars.

Solvent-induced assembly of two helical Eu(III) metal-organic frameworks and fluorescence sensing activities towards nitrobenzene and Cu2+ ions

NASA Astrophysics Data System (ADS)

Ma, Ranran; Chen, Zhiwei; Wang, Suna; Yao, Qingxia; Li, Yunwu; Lu, Jing; Li, Dacheng; Dou, Jianmin

2017-08-01

Two helical Eu(III) metal-organic frameworks, namely, {[Eu(L)(DMF)(H2O)]·0.5DMF}n (1) and [Eu(L)(DEF)(H2O)]n (2) (H3L=3,5-bis(2-carboxylphenoxy)benzoic acid, DMF=N,N-dimethylformamide, DEF=N,N-diethylformamide), have been solvothermally synthesized in different solvents, respectively. Both complexes possess helical structures through the connectivity of Eu atoms and phenolic-oxygen containing branches of the flexible multicarboxylate ligand. Based on different helices, these two complexes exhibited hexagonal and tetragonal channels, respectively. Both complexes possess (3,6)-connected (4.62)2(42.610.83) topology but with different long Schlafli symbol. The solvent plays an important role in the formation of the final frameworks. Both complexes can sensitively and selectively detect nitrobenzene and Cu2+ ions.

Kinetic analysis of the non-isothermal crystallization process, magnetic and mechanical properties of FeCoBSiNb and FeCoBSiNbCu bulk metallic glasses

NASA Astrophysics Data System (ADS)

Ramasamy, Parthiban; Stoica, Mihai; Taghvaei, A. H.; Prashanth, K. G.; Ravi Kumar, Eckert, Jürgen

2016-02-01

The crystallization kinetics of [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 and {[(Fe0.5Co0.5)0.75B0.2Si0.05]0.96Nb0.04}99.5Cu0.5 bulk metallic glasses were evaluated using differential scanning calorimetry under non-isothermal condition. The fully glassy rods with diameters up to 2 mm were obtained by copper mold injection casting. Both glasses show good thermal stability, but the addition of only 0.5% Cu completely changes the crystallization behavior. The average activation energy required for crystallization decreases from 645 kJ/mol to 425 kJ/mol after Cu addition. Upon heating, the Cu-free alloy forms only the metastable Fe23B6 phase. In contrast, two well-separated exothermic events are observed for the Cu-added bulk glassy samples. First, the (Fe,Co) phase nucleates and then (Fe,Co)2B and/or (Fe,Co)3B crystallize from the remaining glassy matrix. The Cu-added alloy exhibits a lower coercivity and a higher magnetic saturation than the base alloy, both in as-cast as well as in annealed condition. Besides, the Cu-added glassy sample with 2 mm diameter exhibits a maximum compressive fracture strength of 3913 MPa together with a plastic strain of 0.6%, which is highest plastic strain ever reported for 2 mm diameter ferromagnetic bulk metallic glass sample. Although Cu addition improves the magnetic and mechanical properties of the glass, it affects the glass-forming ability of the base alloy.

Efficient photocatalytic degradation of rhodamine-B by Fe doped CuS diluted magnetic semiconductor nanoparticles under the simulated sunlight irradiation

NASA Astrophysics Data System (ADS)

Sreelekha, N.; Subramanyam, K.; Amaranatha Reddy, D.; Murali, G.; Rahul Varma, K.; Vijayalakshmi, R. P.

2016-12-01

The present work is planned for a simple, inexpensive and efficient approach for the synthesis of Cu1-xFexS (x = 0.00, 0.01, 0.03, 0.05 and 0.07) nanoparticles via simplistic chemical co-precipitation route by using ethylene diamine tetra acetic acid (EDTA) as a capping molecules. As synthesized nanoparticles were used as competent catalysts for degradation of rhodamine-B organic dye pollutant. The properties of prepared samples were analyzed with energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible optical absorption spectroscopy, Fourier transform infrared (FTIR) spectra, Raman spectra and vibrating sample magnetometer (VSM). EDAX spectra corroborated the existence of Fe in prepared nanoparticles within close proximity to stoichiometric ratio. XRD, FTIR and Raman patterns affirmed that configuration of single phase hexagonal crystal structure as that of (P63/mmc) CuS, without impurity crystals. The average particle size estimated by TEM scrutiny is in the assortment of 5-10 nm. UV-visible optical absorption measurements showed that band gap narrowing with increasing the Fe doping concentration. VSM measurements revealed that 3% Fe doped CuS nanoparticles exhibited strong ferromagnetism at room temperature and changeover of magnetic signs from ferromagnetic to the paramagnetic nature with increasing the Fe doping concentration in CuS host lattice. Among all Fe doped CuS nanoparticles, 3% Fe inclusion CuS sample shows better photocatalytic performance in decomposition of RhB compared with the pristine CuS. Thus as synthesized Cu0·97Fe0·03S nanocatalysts are tremendously realistic compounds for photocatalytic fictionalization in the direction of organic dye degradation under visible light.

Magnetization-induced enhancement of photoluminescence in core-shell CoFe{sub 2}O{sub 4}@YVO{sub 4}:Eu{sup 3+} composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Yanmin, E-mail: ymjia@zjnu.edu.cn, E-mail: wuzheng@zjnu.cn; Zhou, Zhihua; Wei, Yongbin

2013-12-07

After the core-shell CoFe{sub 2}O{sub 4}@YVO{sub 4}:Eu{sup 3+} composite synthesized through a facile sol-gel method was magnetized under an external magnetic field of 0.25 T for 4 h, an enhancement of ∼56% in photoluminescence intensity was observed. The remanent magnetization of the CoFe{sub 2}O{sub 4} core increases the intensity of the excited charge transfer transition of VO{sub 4}{sup 3−} group in YVO{sub 4}:Eu{sup 3+} shell, which may enhance the probability related to the Eu{sup 3+} radiative transition {sup 5}D{sub 0}-{sup 7}F{sub 2}, yielding to a high photoluminescence. The obvious remanent-magnetization-induced enhancement in photoluminescence is helpful in developing excellent magnetic/luminescent material for themore » practical display devices.« less

Iron, Manganese and Copper Release from Synthetic Hydroxyapatite

NASA Technical Reports Server (NTRS)

Sutter, B.; Hossner, L. R.; Ming, Douglas W.

1999-01-01

Kinetic stir-flow dissolution experiments were performed on iron- (Fe-SHA), manganese- (Mn-SHA), and copper- (Cu-SHA) containing synthetic hydroxyapatites. Solution treatments consisted of de-ionized water, citric acid and DTPA. Initially, Mn concentrations were higher than Cu concentrations and Fe concentrations were the lowest in all treatments. At later times Mn and Cu concentrations dropped in the DTPA treatment while Fe rose to the concentration similar to Mn and Cu. At all times, metal release concentrations in the water and citric acid treatments followed the trend of Mn>Cu>Fe. Rietveld analysis of x-ray diffraction data and ^31P NMR indicated that the metals substituted for Ca in the SHA structure. However, EPR data suggested that a metal (hydr)oxide phase existed either on the SHA surface or between the SHA crystallites. The metal concentration trend of Mn>Cu>Fe suggested that the initial solution metal concentrations are dependent on the dissolution of (hydr)oxides from SHA surfaces or between SHA crystallites. Similar metal concentrations at later times in the DTPA experiments suggests that metal concentrations were controlled by the release of Mn, Cu, or Fe from the SHA structure.

Solubility of copper in silicate melts as function of oxygen and sulfur fugacities, temperature, and silicate composition

NASA Astrophysics Data System (ADS)

Holzheid, A.; Lodders, K.

2001-06-01

The solubility of Cu in silicate melts coexisting with liquid Cu(Fe) metal and liquid Cu(Fe) sulfide was determined experimentally at oxygen fugacities ranging from 10 -9.1 to 10 -13.6 bar and sulfur fugacities ranging from 10 -2.5 to 10 -6.3 bar at 1300°C. An iron oxide-free silicate of anorthite-diopside eutectic composition and a synthetic MgO-rich basaltic silicate (FeO-bearing) were used in the partitioning experiments. In S-containing systems, some of the metal reacted to metal sulfide. The silicates in the four systems investigated (Fe-free and S-free; Fe-containing and S-free; Fe-free and S-containing; Fe-containing and S-containing) had different colors depending on the dissolved Cu species and the presence of iron and/or sulfur. Irrespective of the presence of sulfur, the solubility of Cu in the silicate increases with increasing oxygen fugacity and metal/silicate partition coefficients for Cu decrease. Increasing the temperature from 1300°C to 1514°C increases the Cu solubility (decreases the metal/silicate partition coefficient) at an oxygen fugacity 0.5 log units below the iron-wüstite (IW) equilibrium in the Fe-free, S-free and Fe-containing, S-free systems. We infer the presence of monovalent Cu + ("CuO 0.5") in the silicate melt on the basis of the solubility of Cu as function of oxygen fugacity. Experiments containing iron yield a formal valence of ˜0.5 for Cu at very low oxygen fugacities, which is not observed in Fe-free systems. The low formal valence is explained by redox reactions between iron and copper in the silicate melts. There is no evidence for sulfidic dissolution of Cu in the silicates but sulfur has indirect effects on Cu partitioning. Iron metal/silicate partition coefficients depend on oxygen fugacity and on sulfur fugacity. Sulfidic dissolution of iron and oxide-sulfide exchange reactions with Cu cause a small increase in Cu metal/silicate partition coefficients. We derive an activity coefficient (γ CuO 0.5) of 10 ± 1 for liquid CuO 0.5 at 1300°C for the silicate melts used here. A comparison with literature data shows that log γ CuO 0.5 increases in proportion to the mass percentages [CaO +(Al 2O 3)/2] in silicate melts. We recommend the following equations for Cu metal/silicate and sulfide/silicate partitioning for geochemical and cosmochemical modeling if silicate composition and the activity of Cu in the metal or sulfide is known: log D met/sil = -0.48 - 0.25 · log fO 2 - log γ Cu metal + 0.02 · [CaO + (Al 2O 3)/2; wt%] silicate logD sul/sil=+0.76-0.25 · logfO 2+0.25logfS 2-logγ CS 0.5,sulfide +0.02 · [CaO+Al 2O 3/2;wt%] silicate. The derived Cu metal/silicate and metal/sulfide partition coefficients are applied to core formation in the Earth and Mars. The observed Cu abundances in the Earth cannot be easily explained by simple core-mantle equilibrium, but the observed Cu abundances for Mars are consistent with core-mantle equilibrium at low pressure and temperatures.

Periodic table of 3d-metal dimers and their ions.

PubMed

Gutsev, G L; Mochena, M D; Jena, P; Bauschlicher, C W; Partridge, H

2004-10-08

The ground states of the mixed 3d-metal dimers TiV, TiCr, TiMn, TiFe, TiCo, TiNi, TiCu, TiZn, VCr, VMn, VFe, VCo, VNi, VCu, VZn, CrMn, CrFe, CrCo, CrNi, CrCu, CrZn, MnFe, MnCo, MnNi, MnCu, MnZn, FeCo, FeNi, FeCu, FeZn, CoNi, CoCu, CoZn, NiCu, NiZn, and CuZn along with their singly negatively and positively charged ions are assigned based on the results of computations using density functional theory with generalized gradient approximation for the exchange-correlation functional. Except for TiCo and CrMn, our assignment agrees with experiment. Computed spectroscopic constants (r(e),omega(e),D(o)) are in fair agreement with experiment. The ground-state spin multiplicities of all the ions are found to differ from the spin multiplicities of the corresponding neutral parents by +/-1. Except for TiV, MnFe, and MnCu, the number of unpaired electrons, N, in a neutral ground-state dimer is either N(1)+N(2) or mid R:N(1)-N(2)mid R:, where N(1) and N(2) are the numbers of unpaired 3d electrons in the 3d(n)4s(1) occupation of the constituent atoms. Combining the present and previous results obtained at the same level of theory for homonuclear 3d-metal and ScX (X=Ti-Zn) dimers allows one to construct "periodic" tables of all 3d-metal dimers along with their singly charged ions.

Octahedral rotation patterns in strained EuFeO 3 and other Pbnm perovskite films: Implications for hybrid improper ferroelectricity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choquette, A. K.; Smith, C. R.; Sichel-Tissot, R. J.

2016-07-01

We report the relationship between epitaxial strain and the crystallographic orientation of the in-phase rotation axis and A-site displacements in Pbnm-type perovskite films. Synchrotron diffraction measurements of EuFeO3 films under strain states ranging from 2% compressive to 0.9% tensile on cubic or rhombohedral substrates exhibit a combination of a(-)a(+)c(-) and a(+)a(-)c(-) rotational patterns. We compare the EuFeO3 behavior with previously reported experimental and theoretical work on strained Pbnm-type films on nonorthorhombic substrates, as well as additional measurements from LaGaO3, LaFeO3, and Eu0.7Sr0.3MnO3 films on SrTiO3. Compiling the results from various material systems reveals a general strain dependence in which compressivemore » strain strongly favors a(-)a(+)c(-) and a(+)a(-)c(-) rotation patterns and tensile strain weakly favors a(-)a(-)c(+) structures. In contrast, EuFeO3 films grown on Pbnm-type GdScO3 under 2.3% tensile strain take on a uniform a(-)a(+)c(-) rotation pattern imprinted from the substrate, despite strain considerations that favor the a(-)a(-)c(+) pattern. These results point to the use of substrate imprinting as a more robust route than strain for tuning the crystallographic orientations of the octahedral rotations and A-site displacements needed to realize rotation-induced hybrid improper ferroelectricity in oxide heterostructures.« less

Octahedral rotation patterns in strained EuFeO 3 and other Pbnm perovskite films: Implications for hybrid improper ferroelectricity

DOE PAGES

Choquette, A. K.; Smith, C. R.; Sichel-Tissot, R. J.; ...

2016-07-07

Here, we report the relationship between epitaxial strain and the crystallographic orientation of the in-phase rotation axis and A -site displacements in Pbnm-type perovskite films. Synchrotron diffraction measurements of EuFeO 3 films under strain states ranging from 2% compressive to 0.9% tensile on cubic or rhombohedral substrates exhibit a combination of a - a + c - and a + a - c - rotational patterns. We compare the EuFeO 3 behavior with previously reported experimental and theoretical work on strained Pbnm-type films on nonorthorhombic substrates, as well as additional measurements from LaGaO 3 ,more » LaFeO 3 , and Eu 0.7Sr 0.3 MnO 3 films on SrTiO 3 . Compiling the results from various material systems reveals a general strain dependence in which compressive strain strongly favors a - a + c - and a + a - c - rotation patterns and tensile strain weakly favors a - a - c + structures. In contrast, EuFeO 3 films grown on Pbnm-type GdScO 3 under 2.3% tensile strain take on a uniform a - a + c - rotation pattern imprinted from the substrate, despite strain considerations that favor the a - a - c + pattern. Our results point to the use of substrate imprinting as a more robust route than strain for tuning the crystallographic orientations of the octahedral rotations and A -site displacements needed to realize rotation-induced hybrid improper ferroelectricity in oxide heterostructures.« less

Effect of CeLa addition on the microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Jiandi

Development of high strength lithium battery shell alloy is highly desired for new energy automobile industry. The microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy with different CeLa additions were investigated through optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rietveld refinement and tensile testing. Experimental results indicate that Al{sub 8}Cu{sub 4}Ce and Al{sub 6}Cu{sub 6}La phases formed due to CeLa addition. Addition of 0.25 wt.% CeLa could promote the formation of denser precipitation of Al{sub 20}Cu{sub 2}Mn{sub 3} and Al{sub 6}(Mn, Fe) phases, which improved the mechanical properties of the alloy at room temperature.more » However, up to 0.50 wt.% CeLa addition could promote the formation of coarse Al{sub 8}Cu{sub 4}Ce phase, Al{sub 6}Cu{sub 6}La phase and Al{sub 6}(Mn, Fe) phase, which resulted in weakened mechanical properties. - Highlights: •Al-Cu-Mn-Mg-Fe alloys with different CeLa addition were fabricated through casting and rolling. •Al{sub 8}Cu{sub 4}Ce and Al{sub 6}Cu{sub 6}La phases formed after CeLa addition. •Addition of 0.25 wt.% CeLa promoted formation of denser precipitates of Al{sub 20}Cu{sub 2}Mn{sub 3} and Al{sub 6}(Mn, Fe). •Mechanical properties of the alloy was improved after 0.25 wt.% CeLa addition.« less

A GREENER SYNTHESIS OF CORE (FE, CU)-SHELL (AU, PT, PD AND AG) NANOCRYSTALS USING AQUEOUS VITAMIN C

EPA Science Inventory

A greener method to fabricate the novel core (Fe and Cu)-shell (noble metals) metal nanocrystals using aqueous ascorbic acid (vitamin C) is described. Transition metal salts such as Cu and Fe were reduced using ascorbic acid, a benign naturally available antioxidant, and then add...

Heterogeneous photo-Fenton processes using graphite carbon coating hollow CuFe2O4 spheres for the degradation of methylene blue

NASA Astrophysics Data System (ADS)

Guo, Xiaojun; Wang, Kebai; Li, Dai; Qin, Jiabin

2017-10-01

The novel graphite carbon coating hollow CuFe2O4 spheres were fabricated through solvothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectra, etc. The catalytic performance of the graphite carbon coating hollow CuFe2O4 spheres was evaluated in photo-Fenton-like degradation of methylene blue (MB) using H2O2 as a green oxidant under light irradiation (λ > 400 nm). The results demonstrated that the hollow CuFe2O4 spheres with graphite carbon coating exhibited superior catalytic activity. In the preparation process of catalyst, the addition of glucose was very important to its catalytic performance. Photoresponse analysis of the typical samples proved that CuFe2O4@graphite carbon core-shell hollow spheres possessed excellent photocurrent response and lower electrochemical impedance. In addition, a possible mechanism for photocatalytic degradation of MB had been presumed. Moreover, after five regeneration cycles, the graphite carbon coating hollow CuFe2O4 spheres still exhibited better properties.

The role of rare-earth dopants in tailoring the magnetism and magnetic anisotropy in Fe4N

NASA Astrophysics Data System (ADS)

Li, Zirun; Mi, Wenbo; Bai, Haili

2018-05-01

The magnetism and magnetic anisotropy of the rare-earth (RE) atom-substituted Fe4N are investigated by first-principles calculations. It is found that the substitution of one RE atom results in an antiferromagnetic coupling with the Fe atoms. The 4f-3d exchange interaction has an important influence on the density of states of Fe near the Fermi level. PrFe3N and NdFe3N with a tetragonal structure exhibit giant magnetic anisotropy energy larger than 5 meV/atom. The magnetic anisotropy depends on the distribution of partial states of d or f orbital near the Fermi level. As Eu substitutes Fe in Fe4N, the magnetic moment of Eu3FeN even exceeds 23 μB. Our theoretical predictions point out the possibilities of tuning the magnetism and magnetic anisotropy of Fe4N upon RE doping.

Combustion synthesized copper-ion substituted FeAl2O4 (Cu0.1Fe0.9Al2O4): A superior catalyst for methanol steam reforming compared to its impregnated analogue

NASA Astrophysics Data System (ADS)

Maiti, Sayantani; Llorca, Jordi; Dominguez, Montserrat; Colussi, Sara; Trovarelli, Alessandro; Priolkar, Kaustubh R.; Aquilanti, Giuliana; Gayen, Arup

2016-02-01

A series of copper ion substituted MAl2O4 (M = Mg, Mn, Fe and Zn) spinels is prepared by a single step solution combustion synthesis (SCS) and tested for methanol steam reforming (MSR). The copper ion substituted Cu0.1Fe0.9Al2O4 appears to be the most active, showing ∼98% methanol conversion at 300 °C with ∼5% CO selectivity at GHSV = 30,000 h-1 and H2O:CH3OH = 1.1. The analogous impregnated catalyst, CuO (10 at%)/FeAl2O4, is found to be much less active. These materials are characterized by XRD, H2-TPR, BET, HRTEM, XPS and XANES analyses. Spinel phase formation is highly facilitated upon Cu-ion substitution and Cu loading beyond 10 at% leads to the formation of CuO as an additional phase. The ionic substitution of copper in FeAl2O4 leads to the highly crystalline SCS catalyst containing Cu2+ ion sites that are shown to be more active than the dispersed CuO nano-crystallites on the FeAl2O4 impregnated catalyst, despite its lower surface area. The as prepared SCS catalyst contains also a portion of copper as Cu1+ that increases when subjected to reforming atmosphere. The MSR activity of the SCS catalyst decreases with time-on-stream due to the sintering of catalyst crystallites as established from XPS and HRTEM analyses.

Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of Nanostructural Features in Irradiated Fe-Cu-Mn Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wirth, B D; Asoka-Kumar, P; Howell, R H

2001-01-01

Radiation embrittlement of nuclear reactor pressure vessel steels results from a high number density of nanometer sized Cu-Mn-Ni rich precipitates (CRPs) and sub-nanometer matrix features, thought to be vacancy-solute cluster complexes (VSC). However, questions exist regarding both the composition of the precipitates and the defect character and composition of the matrix features. We present results of positron annihilation spectroscopy (PAS) and small angle neutron scattering (SANS) characterization of irradiated and thermally aged Fe-Cu and Fe-Cu-Mn alloys. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of CRPs andmore » VSCs in both alloys. The CRPs are coarser in the Fe-Cu alloy and the number densities of CRP and VSC increase with the addition of Mn. The PAS involved measuring both the positron lifetimes and the Doppler broadened annihilation spectra in the high momentum region to provide elemental sensitivity at the annihilation site. The spectra in Fe-Cu-Mn specimens thermally aged to peak hardness at 450 C and irradiated at 288 C are nearly identical to elemental Cu. Positron lifetime and spectrum measurements in Fe-Cu specimens irradiated at 288 C clearly show the existence of long lifetime ({approx}500 ps) open volume defects, which also contain Cu. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of CRPs and VSCs and tend to discount high Fe concentrations in the CRPs.« less

Correlation of x-ray diffraction and Mössbauer effect measurements with magnetic properties of heat-treated Cu80Co15Fe5 ribbons

NASA Astrophysics Data System (ADS)

Harris, V. G.; Rubinstein, M.; Das, B. N.; Koon, N. C.

1994-05-01

X-ray diffraction (XRD) and Mössbauer Effect (ME) measurements were performed on heat-treated Cu80Co15Fe5 melt-spun ribbons in an attempt to understand the trends in magnetic properties with heat treatment. ME measurements indicate that the majority of Fe atoms (86%) occupy sites in ferromagnetic FCC CoFe clusters after the initial quench. A heat treatment at 900 °C acts to complete the chemical separation of Fe from the Cu matrix. The presence of Co in the Cu matrix, even after high temperature anneals, provides a paramagnetic component that prohibits saturation even at high fields.

Modulation of Jahn-Teller effect on magnetization and spontaneous electric polarization of CuFeO2

NASA Astrophysics Data System (ADS)

Xiao, Guiling; Xia, Zhengcai; Wei, Meng; Huang, Sha; Shi, Liran; Zhang, Xiaoxing; Wu, Huan; Yang, Feng; Song, Yujie; Ouyang, Zhongwen

2018-03-01

CuFe0.99Mn0.01O2 and CuFe0.99Co0.01O2 single crystal samples are grown by a floating zone technique and their magnetization and spontaneous electric polarization have been investigated. Similarly with pure CuFeO2, an obviously anisotropic magnetization and spontaneous electric polarization were observed in the both doped samples, and their phase transition critical fields and temperatures are directly doping ion dependent. Considering the different d-shell configuration and ionic size between Mn3+, Co3+ and Fe3+ ions, in which the Mn3+ ion with Jahn-Teller (J-T) effect has different distortion on the geometry frustration from both of Fe3+ and Co3+ ion. Since for Mn3+ ion, the orbital splitting results from the low-symmetry J-T distortion in a crystal-field environment leads to a distorted MnO6 octahedron, which different from undistorted FeO6 and CoO6 octahedrons. The strain between distorted and undistorted octahedrons produces different effects on the spin reorientation transition and spontaneous electric polarization. Although the pure CuFeO2 has a very strong and robust frustration, the presence of the strain due to the random distribution of distorted MnO6 octahedron and undistorted CoO6 (FeO6) octahedrons leads to its spin reorientation transitions and spontaneous electric polarization different from CuFeO2.

Cation Distribution and Local Configuration of Fe 2+ Ions in Structurally Nonequivalent Lattice Sites of Heterometallic Fe(II)/ M(II) ( M = Mn, Co, Ni, Cu, Zn) Diaquadiformato Complexes

NASA Astrophysics Data System (ADS)

Devillers, M.; Ladrière, J.

1993-03-01

57Fe Mössbauer investigations are carried out on a wide series of heterometallic diaquadiformato Fe(II)/ M(II) complexes with M = Mn, Co, Ni, Cu, and Zn to provide a local picture of the coordination environment of the 57Fe 2+ ions as a function of (i) the nature of the host cation and (ii) the relative amounts of both metals in the matrix (between 50 and 0.25 at.% Fe). Information is obtained on the quantitative distribution of both metals between the two structurally nonequivalent lattice sites and on the local geometry around the dopant atom in each crystal site. In the mixed Fe-Cu complexes. Fe 2+ ions are preferentially incorporated in the tetrahydrated site; in Cu-rich Fe xCu 1- x(HCO 2) 2· 2H 2O, the 57Fe 2+ ions located in the hexaformato-coordinated site are surrounded by an axially compressed octahedron of formate ligands which contrasts with the elongated configuration observed in the pure iron compound and in the other mixed systems. Semiquantitative estimations of the tetragonal field splitting and of the extent of metal-ligand interactions are proposed from the temperature dependence of the quadrupole splitting values.

Synthesis of AlFeCuCrMg{sub x} (x = 0, 0.5, 1, 1.7) alloy powders by mechanical alloying

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maulik, Ornov; Kumar, Vinod, E-mail: vkt.meta@mnit.ac.in; Adjunct Faculty, Materials Research Centre, Malaviya National Institute of Technology, Jaipur 302017

2015-12-15

Novel AlFeCuCrMg{sub x} (x = 0, 0.5, 1, 1.7 mol) high-entropy alloys (HEAs) were synthesized by mechanical alloying. The effect of Mg content on the phase evolution of HEAs was investigated using X-Ray diffractometry (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) pattern analysis. The particle morphology and composition of HEAs were investigated by scanning electron microscopy (SEM). Thermodynamic parameters were calculated and analyzed to explain the formation of a solid solution. XRD analysis revealed BCC as major phase and FCC as a minor phase in as-milled AlFeCuCr and AlFeCuCrMg{sub 0.5} HEAs. Also, XRD analysis of as-milledmore » AlFeCuCrMg, AlFeCuCrMg{sub 1.7} confirmed the formation of two BCC phases (BCC 1 and BCC 2). TEM–SAED analysis of AlFeCuCrMg{sub x} HEAs concurred with XRD results. Microstructural features and mechanism for solid solution formation have been conferred in detail. Phase formation of the present HEAs has been correlated with calculated thermodynamic parameters. Differential thermal analysis (TGA-DTA) of these alloys confirmed that there is no substantial phase change up to 500 °C. - Highlights: • Novel AlFeCuCrMg{sub x} (x = 0, 0.5, 1, 1.7) HEAs were prepared by mechanical alloying. • Phase evolution and lattice parameter were studied by X-Ray Diffraction. • Crystallite size and lattice microstrain calculated failed to obey the Williamson–Hall method. • Criterions for formation of simple solid solution were compared to the thermodynamic parameters of the present HEAs. • Increase in the Mg concentration in AlMg{sub x}FeCuCr (x = 0, 0.5, 1, 1.7) HEAs supports the formation of BCC phase.« less

Rat liver mitochondrial dysfunction by addition of copper(II) or iron(III) ions.

PubMed

Saporito-Magriñá, Christian; Musacco-Sebio, Rosario; Acosta, Juan M; Bajicoff, Sofía; Paredes-Fleitas, Paola; Boveris, Alberto; Repetto, Marisa G

2017-01-01

Increased copper (Cu) and iron (Fe) levels in liver and brain are associated to oxidative stress and damage with increased phospholipid oxidation process. The aim of this work was to assess the toxic effects of Cu 2+ and Fe 3+ addition to rat liver mitochondria by determining mitochondrial respiration in states 3 (active respiration) and 4 (resting respiration), and phospholipid peroxidation. Both, Cu 2+ and Fe 3+ produced decreases in O 2 consumption in a concentration-dependent manner in active state 3: both ions by 42% with malate-glutamate as complex I substrate (concentration for half maximal response (C 50 ) 60μM Cu 2+ and 1.25mM Fe 3+ ), and with succinate as complex II substrate: 64-69% with C 50 of 50μM Cu 2+ and with C 50 of 1.25mM of Fe 3+ . Respiratory control decreased with Cu 2+ (C 50 50μM) and Fe 3+ (C 50 1.25-1-75mM) with both substrates. Cu 2+ produced a 2-fold increase and Fe 3+ a 5-fold increase of thiobarbituric acid-reactive substances (TBARS) content from 25μM Cu 2+ (C 50 40μM) and from 100μM Fe 3+ (C 50 1.75mM). Supplementations with Cu 2+ and Fe 3+ ions induce mitochondrial dysfunction with phospholipid peroxidation in rat liver mitochondria. Although is proved that a Fenton/Haber Weiss mechanism of oxidative damage occurs in metal-ion induced mitochondrial toxicity, slightly different responses to the metal ions suggest some differences in the mechanism of intracellular toxicity. The decreased rates of mitochondrial respiration and the alteration of mitochondrial function by phospholipid and protein oxidations lead to mitochondrial dysfunction, cellular dyshomeostasis and cell death. Copyright © 2016 Elsevier Inc. All rights reserved.

Interfacial magnetism and exchange coupling in BiFeO3-CuO nanocomposite.

PubMed

Chakrabarti, Kaushik; Sarkar, Babusona; Ashok, Vishal Dev; Das, Kajari; Chaudhuri, Sheli Sinha; De, S K

2013-12-20

Ferromagnetic BiFeO3 nanocrystals of average size 9 nm were used to form a composite with antiferromagnetic CuO nanosheets, with the composition (x)BiFeO3/(100-x)CuO, x = 0, 20, 40, 50, 60, 80 and 100. The dispersion of BiFeO3 nanocrystals into the CuO matrix was confirmed by x-ray diffraction and transmission electron microscopy. The ferromagnetic ordering as observed in pure BiFeO3 occurs mainly due to the reduction in the particle size as compared to the wavelength (62 nm) of the spiral modulated spin structure of the bulk BiFeO3. Surface spin disorder of BiFeO3 nanocrystals gives rise to an exponential behavior of magnetization with temperature. Strong magnetic exchange coupling between the BiFeO3 nanocrystal and the CuO matrix induces an interfacial superparamagnetic phase with a blocking temperature of about 80 K. Zero field and field cooled magnetizations are analyzed by a ferromagnetic core and disordered spin shell model. The temperature dependence of the calculated saturation magnetization exhibits three magnetic contributions in three temperature regimes. The BiFeO3/CuO nanocomposites reveal an exchange bias effect below 170 K. The maximum exchange bias field HEB is 1841 Oe for x = 50 at 5 K under field cooling of 50 kOe. The exchange bias coupling results in an increase of coercivity of 1934 Oe at 5 K. Blocked spins within an interfacial region give rise to a remarkable exchange bias effect in the nanocomposite due to strong magnetic exchange coupling between the BiFeO3 nanocrystals and the CuO nanosheets.

Contrasting Physiological and Proteomic Adaptations to Iron and/or Copper Limitation in Two Strains of the Same Open Ocean Diatom Thalassiosira oceanica

NASA Astrophysics Data System (ADS)

Schuback, N.; Hippmann, A.; Maldonado, M. T.; Allen, A. E.; McCrow, J.; Foster, L. J.; Green, B. R.; Alami, M.

2016-02-01

Iron plays a significant role in controlling marine primary productivity. Despite that extremely low dissolved iron (Fe) concentrations are found in Fe-limited regions, some phytoplankton are able to survive and thrive. Two strains of the model oceanic diatom Thalassiosira oceanica, TO 1003 and TO 1005, have both been used in previous studies to characterize adaptations to iron limitation. These studies have shown that T. oceanica has lowered its Fe requirements and increased its Fe acquisition efficiency compared to coastal counterparts. Both strategies may impose a higher cellular copper (Cu) demand. However, the underlying biochemical adaptations in these oceanic diatoms remain unknown. Recently, the genome, as well as the first proteomic and transcriptomic analyses of T. oceanica 1005 grown under different Fe levels, were published. To further our understanding of the interplay between Fe- and Cu- physiology in open ocean diatoms, we examined an array of physiological responses to varying degrees of Fe-, Cu- and Fe/Cu co-limitation in both strains. We also determined the differential expression of proteins using stable isotope labeling and LC-MS/MS proteomic analysis. The two strains, TO 1003 and TO 1005, need markedly different metal concentrations in the media. TO1003 requires 30% less Cu to sustain its optimal growth and less than 1/10th of the minimum Cu that is needed by TO 1005 to survive. In contrast, TO 1005 is able to grow with less Fe available in the media. The physiological and proteomic responses of these two strains when acclimated to low Fe and/or Cu concentrations will be presented. The evolutionary implications will be discussed.

Fabrication and Electromagnetic Properties of Conjugated NH2-CuPc@Fe3O4

NASA Astrophysics Data System (ADS)

Yan, Liang; Pu, Zejun; Xu, Mingzhen; Wei, Renbo; Liu, Xiaobo

2017-10-01

Conjugated amino-phthalocyanine copper containing carboxyl groups/magnetite (NH2-CuPc@Fe3O4) has been fabricated from FeCl3·6H2O and NH2-CuPc via a simple solvothermal method and its electromagnetic properties investigated. Scanning electron microscopy and transmission electron microscopy revealed that the NH2-CuPc@Fe3O4 was a waxberry-like nanomaterial with NH2-CuPc molecules effectively embedded in the interior of Fe3O4 particles in the form of beads. Introduction of NH2-CuPc effectively improved the complementarity between the dielectric and magnetic losses of the system, resulting in excellent electromagnetic performance. The minimum reflection loss of the as-prepared composite reached -33.4 dB at 7.0 GHz for coating layer thickness of 4.0 mm and bandwidth below -10.0 dB (90% absorption) of up to 3.8 GHz. These results indicate that introduction of NH2-CuPc results in a composite with potential for use as an electromagnetic microwave absorption material.

Co-precipitated and collocated carbides and Cu-rich precipitates in a Fe-Cu steel characterized by atom-probe tomography.

PubMed

Kolli, R Prakash; Seidman, David N

2014-12-01

The composition of co-precipitated and collocated NbC carbide precipitates, Fe3C iron carbide (cementite), and Cu-rich precipitates are studied experimentally by atom-probe tomography (APT). The Cu-rich precipitates located at a grain boundary (GB) are also studied. The APT results for the carbides are supplemented with computational thermodynamics predictions of composition at thermodynamic equilibrium. Two types of NbC carbide precipitates are distinguished based on their stoichiometric ratio and size. The Cu-rich precipitates at the periphery of the iron carbide and at the GB are larger than those distributed in the α-Fe (body-centered cubic) matrix, which is attributed to short-circuit diffusion of Cu along the GB. Manganese segregation is not observed at the heterophase interfaces of the Cu-rich precipitates that are located at the periphery of the iron carbide or at the GB, which is unlike those located at the edge of the NbC carbide precipitates or distributed in the α-Fe matrix. This suggests the presence of two populations of NiAl-type (B2 structure) phases at the heterophase interfaces in multicomponent Fe-Cu steels.

3D hierarchical magnetic hollow sphere-like CuFe2O4 combined with HPLC for the simultaneous determination of Sudan I-IV dyes in preserved bean curd.

PubMed

Liu, Xueyan; Qi, Xinyu; Zhang, Lei

2018-02-15

Three-dimensional (3D) hierarchical magnetic hollow sphere-like CuFe 2 O 4 (3D HMHS-CuFe 2 O 4 ) were designed to sensitively detect four Sudan dyes combined with HPLC-DAD. The formation mechanism of 3D HMHS-CuFe 2 O 4 is also discussed. Compared to the particle-like CuFe 2 O 4 (PL-CuFe 2 O 4 ), the as-obtained 3D HMHS-CuFe 2 O 4 provided a higher extraction efficiency for the four Sudan dyes (I, II, III and IV) due to its hierarchical hollow structure with properly interconnected pores where the targets can easily diffuse into the reaction sites. Thus, a magnetic solid-phase extraction (MSPE)-HPLC method was established for the simultaneous measurement of the four Sudan dyes. Under optimized conditions, good linearity (5-4000ngg -1 , r 2 ≥0.9991), limits of detection (LODs, 0.56-0.60ngg -1 ), recoveries (91.1%-99.3%) and precision (RSDs≤4.9%) for the four Sudan dyes were obtained. The proposed MSPE-HPLC-DAD method is a convenient, effective, sensitive and time-saving method for the rapid isolation and determination of four Sudan dyes in preserved bean curd. Copyright © 2017. Published by Elsevier Ltd.

The Gibbs free energy of nukundamite (Cu3.38Fe0.62S4): A correction and implications for phase equilibria

USGS Publications Warehouse

Seal, R.R.; Inan, E.E.; Hemingway, B.S.

2001-01-01

The Gibbs free energy of formation of nukundamite (Cu3.38Fe0.62S4) was calculated from published experimental studies of the reaction 3.25 Cu3.38Fe0.62S4 + S2 = 11 CuS + 2 FeS2 in order to correct an erroneous expression in the published record. The correct expression describing the Gibbs free energy of formation (kJ???mol-1) of nukundamite relative to the elements and ideal S2 gas is ??fG?? nukundamite T(K) = -549.75 + 0.23242 T + 3.1284 T0.5, with an uncertainty of 0.6%. An evaluation of the phase equilibria of nukundamite with associated phases in the system Cu-Fe-S as a function of temperature and sulfur fugacity indicates that nukundamite is stable from 224 to 501??C at high sulfidation states. At its greatest extent, at 434??C, the stability field of nukundamite is only 0.4 log f(S2) units wide, which explains its rarity. Equilibria between nukundamite and bornite, which limit the stability of both phases, involve bornite compositions that deviate significantly from stoichiometric Cu5FeS4. Under equilibrium conditions in the system Cu-Fe-S, nukundamite + chalcopyrite is not a stable assemblage at any temperature.

Transcriptome Sequencing Identifies SPL7-Regulated Copper Acquisition Genes FRO4/FRO5 and the Copper Dependence of Iron Homeostasis in Arabidopsis[C][W

PubMed Central

Bernal, María; Casero, David; Singh, Vasantika; Wilson, Grandon T.; Grande, Arne; Yang, Huijun; Dodani, Sheel C.; Pellegrini, Matteo; Huijser, Peter; Connolly, Erin L.; Merchant, Sabeeha S.; Krämer, Ute

2012-01-01

The transition metal copper (Cu) is essential for all living organisms but is toxic when present in excess. To identify Cu deficiency responses comprehensively, we conducted genome-wide sequencing-based transcript profiling of Arabidopsis thaliana wild-type plants and of a mutant defective in the gene encoding SQUAMOSA PROMOTER BINDING PROTEIN-LIKE7 (SPL7), which acts as a transcriptional regulator of Cu deficiency responses. In response to Cu deficiency, FERRIC REDUCTASE OXIDASE5 (FRO5) and FRO4 transcript levels increased strongly, in an SPL7-dependent manner. Biochemical assays and confocal imaging of a Cu-specific fluorophore showed that high-affinity root Cu uptake requires prior FRO5/FRO4-dependent Cu(II)-specific reduction to Cu(I) and SPL7 function. Plant iron (Fe) deficiency markers were activated in Cu-deficient media, in which reduced growth of the spl7 mutant was partially rescued by Fe supplementation. Cultivation in Cu-deficient media caused a defect in root-to-shoot Fe translocation, which was exacerbated in spl7 and associated with a lack of ferroxidase activity. This is consistent with a possible role for a multicopper oxidase in Arabidopsis Fe homeostasis, as previously described in yeast, humans, and green algae. These insights into root Cu uptake and the interaction between Cu and Fe homeostasis will advance plant nutrition, crop breeding, and biogeochemical research. PMID:22374396

High-Performance Epoxy-Resin-Bonded Magnets Produced from the Sm2Fe17Nx Powders Coated by Copper and Zinc Metals

NASA Astrophysics Data System (ADS)

Noguchi, Kenji; Machida, Ken-ichi; Adachi, Gin-ya

2001-04-01

Fine powders of Sm2Fe17Nx coated with copper metal reduced from CuCl2 and/or zinc metal subsequently derived by photo-decomposition of diethylzinc [Zn(C2H5)2] were prepared, and their magnetic properties were characterized in addition to those of epoxy-resin-bonded magnets produced from the coated powders (Cu/Sm2Fe17Nx, Zn/Sm2Fe17Nx and Zn/Cu/Sm2Fe17Nx). The remanence (Br) and maximum energy product [(\\mathit{BH})max] of double metal-coated Zn/Cu/Sm2Fe17Nx powders were maintained at higher levels than those of single Zn metal-coated Sm2Fe17Nx ones (Zn/Sm2Fe17Nx) even after heat treatment at 673 K since the oxidation resistance and thermal stability were effectively improved by formation of the thick and uniform protection layer on the surface of Sm2Fe17Nx particles. Moreover, the epoxy-resin-bonded magnets produced from the Zn/Cu/Sm2Fe17Nx powders possessed good corrosion resistance in air at 393 K which it resulted in the smaller thermal irreversible flux loss than that of uncoated and single Zn metal-coated Sm2Fe17Nx powders in the temperature range of above 393 K.

Impact of a long term fire retardant (Fire Trol 931) on the leaching of Na, Al, Fe, Mn, Cu and Si from a Mediterranean forest soil: a short-term, lab-scale study.

PubMed

Koufopoulou, Sofia; Michalopoulos, Charalampos; Tzamtzis, Nikolaos; Pappa, Athina

2014-06-01

Long term fire retardant (LTR) application for forest fire prevention purposes as well as wildland fires can result in chemical leaching from forest soils. Large quantities of sodium (Na), aluminium (Al), iron (Fe), manganese (Mn), copper (Cu) and silicon (Si) in leachates, mainly due to ammonium (one of the major LTR components) soil deposition, could affect the groundwater quality. The leaching of Na, Al, Fe, Mn, Cu and Si due to nitrogen based LTR application (Fire Trol 931) was studied at laboratory scale. The concentrations of Na(+), Al(3+), Fe(3+)/Fe(2+), Mn(2+), Cu(2+) and Si(4+) were measured in the resulting leachates from pots with forest soil and pine trees alone and in combination with fire. The leaching of Na, Fe and Si from treated pots was significantly greater than that from control pots. The leaching of Al, Mn and Cu was extremely low.

Fabrication of Fe3O4@CuO core-shell from MOF based materials and its antibacterial activity

NASA Astrophysics Data System (ADS)

Rajabi, S. K.; Sohrabnezhad, Sh.; Ghafourian, S.

2016-12-01

Magnetic Fe3O4@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe3O4@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe3O4 core and a CuO shell. The Fe3O4@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe3O4-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

An empirical method for estimating instream pre-mining pH and dissolved Cu concentration in catchments with acidic drainage and ferricrete

USGS Publications Warehouse

Nimick, D.A.; Gurrieri, J.T.; Furniss, G.

2009-01-01

Methods for assessing natural background water quality of streams affected by historical mining are vigorously debated. An empirical method is proposed in which stream-specific estimation equations are generated from relationships between either pH or dissolved Cu concentration in stream water and the Fe/Cu concentration ratio in Fe-precipitates presently forming in the stream. The equations and Fe/Cu ratios for pre-mining deposits of alluvial ferricrete then were used to reconstruct estimated pre-mining longitudinal profiles for pH and dissolved Cu in three acidic streams in Montana, USA. Primary assumptions underlying the proposed method are that alluvial ferricretes and modern Fe-precipitates share a common origin, that the Cu content of Fe-precipitates remains constant during and after conversion to ferricrete, and that geochemical factors other than pH and dissolved Cu concentration play a lesser role in determining Fe/Cu ratios in Fe-precipitates. The method was evaluated by applying it in a fourth, naturally acidic stream unaffected by mining, where estimated pre-mining pH and Cu concentrations were similar to present-day values, and by demonstrating that inflows, particularly from unmined areas, had consistent effects on both the pre-mining and measured profiles of pH and Cu concentration. Using this method, it was estimated that mining has affected about 480 m of Daisy Creek, 1.8 km of Fisher Creek, and at least 1 km of Swift Gulch. Mean values of pH decreased by about 0.6 pH units to about 3.2 in Daisy Creek and by 1-1.5 pH units to about 3.5 in Fisher Creek. In Swift Gulch, mining appears to have decreased pH from about 5.5 to as low as 3.6. Dissolved Cu concentrations increased due to mining almost 40% in Daisy Creek to a mean of 11.7 mg/L and as much as 230% in Fisher Creek to 0.690 mg/L. Uncertainty in the fate of Cu during the conversion of Fe-precipitates to ferricrete translates to potential errors in pre-mining estimates of as much as 0.25 units for pH and 22% for dissolved Cu concentration. The method warrants further testing in other mined and unmined watersheds. Comparison of pre-mining water-quality estimates derived from the ferricrete and other methods in single watersheds would be particularly valuable. The method has potential for use in monitoring remedial efforts at mine sites with ferricrete deposits. A reasonable remediation objective might be realized when the downstream pattern of Fe/Cu ratios in modern streambed Fe-precipitates corresponds to the pattern in pre-mining alluvial ferricrete deposits along a stream valley.

Chemical Complexity in the Eu-enhanced Monometallic Globular NGC 5986

NASA Astrophysics Data System (ADS)

Johnson, Christian I.; Caldwell, Nelson; Rich, R. Michael; Mateo, Mario; Bailey, John I., III; Olszewski, Edward W.; Walker, Matthew G.

2017-06-01

NGC 5986 is a poorly studied but relatively massive Galactic globular cluster that shares several physical and morphological characteristics with “iron-complex” clusters known to exhibit significant metallicity and heavy-element dispersions. In order to determine whether NGC 5986 joins the iron-complex cluster class, we investigated the chemical composition of 25 red giant branch and asymptotic giant branch cluster stars using high-resolution spectra obtained with the Magellan-M2FS instrument. Cluster membership was verified using a combination of radial velocity and [Fe/H] measurements, and we found the cluster to have a mean heliocentric radial velocity of +99.76 km s-1 (σ = 7.44 km s-1). We derived a mean metallicity of [Fe/H] = -1.54 dex (σ = 0.08 dex), but the cluster’s small dispersion in [Fe/H] and low [La/Eu] abundance preclude it from being an iron-complex cluster. NGC 5986 has < [{Eu}/{Fe}]> =+0.76 {dex} (σ = 0.08 dex), which is among the highest ratios detected in a Galactic cluster, but the small [Eu/Fe] dispersion is puzzling because such high values near [Fe/H] ˜ -1.5 are typically only found in dwarf galaxies exhibiting large [Eu/Fe] variations. NGC 5986 exhibits classical globular cluster characteristics, such as uniformly enhanced [α/Fe] ratios, a small dispersion in Fe-peak abundances, and (anti)correlated light-element variations. Similar to NGC 2808, we find evidence that NGC 5986 may host at least four to five populations with distinct light-element compositions, and the presence of a clear Mg-Al anticorrelation along with an Al-Si correlation suggests that the cluster gas experienced processing at temperatures ≳65-70 MK. However, the current data do not support burning temperatures exceeding ˜100 MK. We find some evidence that the first- and second-generation stars in NGC 5986 may be fully spatially mixed, which could indicate that the cluster has lost a significant fraction of its original mass. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Optical absorption and disorder in delafossites

DOE PAGES

Senty, Tess R.; Haycock, Barry; Lekse, Jonathan; ...

2017-07-06

Here, we present compelling experimental results of the optical characteristics of transparent oxide CuGaO 2 and related CuGa 1-xFe xO 2 (with 0.00 ≤ x ≤ 0.05) alloys, whereby the forbidden electronic transitions for CuGaO 2 become permissible in the presence of B-site (Ga sites) alloying with Fe. Our computational structural results imply a correlation between the global strain on the system and a decreased optical absorption edge. However, herein, we show that the relatively ordered CuGa 1-xFe xO 2 (for 0.00 ≤ x ≤ 0.04) structures exhibit much weaker vis-absorption compared to the relatively disordered CuGa 0.95Fe 0.05O 2.

Different recycle behavior of Cu2+ and Fe3+ ions for phenol photodegradation over TiO2 and WO3.

PubMed

Wan, Lianghui; Sheng, Jiayi; Chen, Haihang; Xu, Yiming

2013-11-15

Photocatalytic degradation of organic pollutants on TiO2 and WO3 have been widely studied, but the effects of Cu(2+) and Fe(3+) ions still remain unclear. In this work, we have found that the recycle behavior of Cu(2+) and Fe(3+) are greatly dependent on the photocatalytic activity of metal oxide used. With TiO2 (P25, anatase, and rutile), all the time profiles of phenol degradation in water under UV light well fitted to the apparent first-order rate equation. On the addition of Cu(2+), phenol degradation on anatase, rutile and WO3 also followed the first-order kinetics. On the addition of Fe(3+), the initial rate of phenol degradation on each oxide was increased, but only the reactions on three TiO2 became to follow the first order kinetics after half an hour. The relevant rate constants for phenol degradation in the presence of Cu(2+) or Fe(3+) were larger than those in the absence of metal ions. Under visible light, phenol degradation on WO3 was also accelerated on the addition of Fe(3+) or Cu(2+). Moreover, several influencing factors were examined, including the metal ion photolysis in solution. It becomes clear that as electron scavengers of TiO2 and WO3, Fe(3+) is better than Cu(2+), while they are better than O2. We propose that Fe(3+) recycle occurs through H2O2, photogenerated from TiO2, not from WO3, while Cu(2+) regeneration on a moderate photocatalyst is through the dissolved O2 in water. Copyright © 2013. Published by Elsevier B.V.

Discrimination of Venezuelan spirituous beverages by a trace element-radial basis neural network approach.

PubMed

Hernández-Caraballo, Edwin A; Avila de Hernández, Rita M; Rivas-Echeverría, Francklin; Capote-Luna, Tarcisio

2008-01-15

Radial basis neural networks (RBNNs) were developed and evaluated for discrimination of specimens of 'aguardiente de Cocuy', a spirituous beverage produced in the northwestern region of Venezuela. The beverage is distilled from the must of Agave cocui Trelease in an artisanship fashion with little quality control. Forty specimens, with known concentrations of copper, iron, and zinc, were used in this study. The specimens were previously collected in various locations around Sucre Municipality (Falcón State) and Urdaneta Municipality (Lara State). The normalized concentrations of these elements served as indirect descriptors of origin (input data). They were presented to the neural networks through 1-3 input nodes in seven different combinations. In addition, two categories (two collection sites) and four categories (two collection sites+two manufacturing conditions) were designated as output data, in order to assess the impact of such selection on the discrimination performance. The overall performance of the four-category RBNNs was as follows (the input data is indicated in parentheses): (Cu-Fe)>(Cu-Zn)>(Cu)>(Zn)>(Fe-Zn)>(Cu-Fe-Zn)>(Fe). In this case, the highest percentage of correct hits was 82.5%. For the two-category RBNNs, the performance decreased as indicated below: (Cu)>(Cu-Fe)>(Cu-Zn)>(Fe-Zn)>(Zn) approximately (Cu-Fe-Zn)>(Fe). The reduction in the number of categories led to an increase in the discrimination performance of all the RBNNs, the best of which was 90.0%. The possibility of discriminating specimens of 'aguardiente de Cocuy' with such an accuracy, based on a single-element determination, is particularly attractive as it would result in a reduction of analysis' costs and laboratory's response time.

Eu9Cd4-xCM2+x-y□ySb9: Ca9Mn4Bi9-type structure stuffed with coinage metals (Cu, Ag, and Au) and the challenges with classical valence theory in describing these possible zintl phases.

PubMed

Kazem, Nasrin; Hurtado, Antonio; Klobes, Benedikt; Hermann, Raphaël P; Kauzlarich, Susan M

2015-02-02

The synthesis, crystal structure, magnetic properties, and europium Mössbauer spectroscopy of the new members of the 9-4-9 Zintl family of Eu(9)Cd(4-x)CM(2+x-y)□(y)Sb(9) (CM = coinage metal: Au, Ag, and Cu) are reported. These compounds crystallize in the Ca(9)Mn(4)Bi(9) structure type (9-4-9) with the 4g interstitial site almost half-occupied by coinage metals; these are the first members in the 9-4-9 family where the interstitial positions are occupied by a monovalent metal. All previously known compounds with this structure type include divalent interstitials where these interstitials are typically the same as the transition metals in the anionic framework. Single-crystal magnetic susceptibility data indicate paramagnetic behavior for all three compounds with antiferromagnetic ordering below 10 K (at 100 Oe) that shifts to lower temperature (<7 K) by applying a 3 T magnetic field. (151)Eu Mössbauer spectra were collected on polycrystalline powder samples of Eu(9)Cd(4-x)CM(2+x-y)□(y)Sb(9) at 50 and 6.5 K in order to evaluate the valence of Eu cations. Although the Zintl formalism states that the five crystallographically distinct Eu sites in Eu(9)Cd(4-x)CM(2+x-y)□(y)Sb9 should bear Eu(2+), the Mössbauer spectral isomer shifts are clearly indicative of both 2+ and 3+ valence of the Eu cations with the Cu- and Au-containing compounds showing higher amounts of Eu(3+). This electronic configuration leads to an excess of negative charge in these compounds that contradicts the expected valence-precise requirement of Zintl phases. The spectra obtained at 6.5 K reveal magnetic ordering for both Eu(2+) and Eu(3+). The field dependence of Eu(2+) indicates two distinct magnetic sublattices, with higher and lower fields, and of a small field for Eu(3+). The site symmetry of the five Eu sites is not distinguishable from the Mössbauer data.

A resumable two-photon fluorescent probe for Cu2+ and S2- based on magnetic silica core-shell Fe3O4@SiO2 nanoparticles and its application in bioimaging.

PubMed

Jiang, Huie; Liu, Yan; Luo, Weifang; Wang, Yujiao; Tang, Xiaoliang; Dou, Wei; Cui, Yumei; Liu, Weisheng

2018-07-19

A two-photon fluorescent probe for Cu 2+ and S 2- has been strategically prepared with naphthalimide derivative platform (NPE) covalently grafted onto the surface of magnetic core-shell Fe 3 O 4 @SiO 2 nanoparticles. The probe (NPE-Fe 3 O 4 @SiO 2 ) exhibits selective response to Cu 2+ with enhanced fluorescence and efficient separation of Cu 2+ with external magnetic field. The consequent product NPE-Fe 3 O 4 @SiO 2 -Cu of NPE-Fe 3 O 4 @SiO 2 and Cu 2+ can work as an excellent sensor for S 2- by removing Cu 2+ from the complex with fluorescence decreased, recovering the fluorescence of the probe. Therefore, the constituted Off-On-Off type fluorescence monitoring system means the probe is resumable. Moreover, the probe has been used to quantitatively detect Cu 2+ and S 2- with low detection limits, which are 0.28 μM and 0.12 μM, respectively. Furthermore, the probe shows low cytotoxicity and excellent membrane permeability, which has been successfully applied for monitoring Cu 2+ and S 2- in living cells and imaging Cu 2+ in deep-tissue with two-photon excited fluorescence. Copyright © 2018. Published by Elsevier B.V.

Giant magnetoresistance enhancement in spin valves with nano-oxide layers

NASA Astrophysics Data System (ADS)

Lai, Chih-Huang; Chen, C. J.; Chin, T. S.

2001-06-01

The magnetoresistance (MR) ratio is enhanced by 35% by inserting the nano-oxide layer (NOL) at the Ta/Co interface in the FeMn-based top spin valves (Ta/NOL/Co/Cu/Co/FeMn/Ta). The enhancement is attributed to specular reflection, resulting in a large resistance change and small sheet resistance. However, the formation of NOL at the interface of Ta/Co suppresses the (111) texture, resulting in small exchange fields. Top spin valves with NOLs show good thermal stability up to 200 °C annealing. The MR ratio is further increased after annealing at temperatures below 200 °C. Enhancement of the MR ratio by 61% can be achieved by annealing at 150 °C. For bottom spin valves (Ta/NiFe/FeMn/Co/Cu/NiFe/Ta), NOLs formed at FeMn/Co and NiFe/Ta interfaces increase MR ratios, but NOLs at Co/Cu or Cu/NiFe deteriorate the differential spin scattering and significantly reduce MR ratios.

Heavy metals in water, sediments, plants and fish of Kali Nadi U. P. (India)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ajmal, M.; Uddin, R.; Khan, A.U.

1988-01-01

The distribution of heavy metals viz., Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the water, sediments, plants and fish samples collected from the Kali Nadi (India) have been determined. The studies have shown that there was considerable variation in the concentration of heavy metals from one sampling station to the other which may be due to the variation in the quality of industrial and sewage wastes being added to the river at different places. The orders of the concentration of heavy metals in water, sediments, plants (Eicchornia crassipes) and fish (Heteropnuestes fossilis) were Fe > Znmore » > Cu > Mn > Cr > Ni > Pb > Co > Cd; Fe > Zn > Mn > Ni > Cr > Co > Cu > Pb > Cd; Fe > Mn > Zn > Cu > Ni > Co > Pb > Cr > Cd and Fe > Zn > Mn > Ni > Pb >Co > Cr > Cu > Cd, respectively.« less

Integrated photooxidative extractive deep desulfurization using metal doped TiO2 and eutectic based ionic liquid

NASA Astrophysics Data System (ADS)

Zaid, Hayyiratul Fatimah Mohd; Kait, Chong Fai; Mutalib, Mohamed Ibrahim Abdul

2016-11-01

A series of metal doped TiO2 namely Fe/TiO2, Cu/TiO2 and Cu-Fe/TiO2 were synthesized and characterized, to be used as a photocatalyst in the integrated photooxidative extractive deep desulfurization for model oil (dodecane) and diesel fuel. The order of the photocatalytic activity was Cu-Fe/TiO2 followed by Cu/TiO2 and then Fe/TiO2. Cu-Fe/TiO2 was an effective photocatalyst for sulfur conversion at ambient atmospheric pressure. Hydrogen peroxide was used as the source of oxidant and eutectic-based ionic liquid as the extractant. Sulfur conversion in model oil reached 100%. Removal of sulfur from model oil was done by two times extraction with a removal of 97.06% in the first run and 2.94% in the second run.

Low-temperature heat capacity and entropy of chalcopyrite (CuFeS2): estimates of the standard molar enthalpy and Gibbs free energy of formation of chalcopyrite and bornite (Cu5FeS4)

USGS Publications Warehouse

Robie, R.A.; Wiggins, L.B.; Barton, P.B.; Hemingway, B.S.

1985-01-01

The heat capacity of CuFeS2 (chalcopyrite) was measured between 6.3 and 303.5 K. At 298.15 K, Cp,mo and Smo(T) are (95.67??0.14) J??K-1??mol-1 and (124.9??0.2) J??K-1??mol-1, respectively. From a consideration of the results of two sets of equilibrium measurements we conclude that ??fHmo(CuFeS2, cr, 298.15 K) = -(193.6??1.6) kJ??mol-1 and that the recent bomb-calorimetric determination by Johnson and Steele (J. Chem. Thermodynamics 1981, 13, 991) is in error. The standard molar Gibbs free energy of formation of bornite (Cu5FeS4) is -(444.9??2.1) kJ??mol-1 at 748 K. ?? 1985.

X-ray absorption fine structure and x-ray diffraction studies of crystallographic grains in nanocrystalline FePd:Cu thin films

NASA Astrophysics Data System (ADS)

Krupinski, M.; Perzanowski, M.; Polit, A.; Zabila, Y.; Zarzycki, A.; Dobrowolska, A.; Marszalek, M.

2011-03-01

FePd alloys have recently attracted considerable attention as candidates for ultrahigh density magnetic storage media. In this paper we investigate FePd thin alloy film with a copper admixture composed of nanometer-sized grains. [Fe(0.9 nm)/Pd(1.1 nm)/Cu(d nm)]×5 multilayers were prepared by thermal deposition at room temperature in UHV conditions on Si(100) substrates covered by 100 nm SiO2. The thickness of the copper layer has been changed from 0 to 0.4 nm. After deposition, the multilayers were rapidly annealed at 600 °C in a nitrogen atmosphere, which resulted in the creation of the FePd:Cu alloy. The structure of alloy films obtained this way was determined by x-ray diffraction (XRD), glancing angle x-ray diffraction, and x-ray absorption fine structure (EXAFS). The measurements clearly showed that the L10 FePd:Cu nanocrystalline phase has been formed during the annealing process for all investigated copper compositions. This paper concentrates on the crystallographic grain features of FePd:Cu alloys and illustrates that the EXAFS technique, supported by XRD measurements, can help to extend the information about grain size and grain shape of poorly crystallized materials. We show that, using an appropriate model of the FePd:Cu grains, the comparison of EXAFS and XRD results gives a reasonable agreement.

Phase-transformation in iron oxide and formation of Cu/γ-Fe2O3 nanocomposite using radio-frequency sputtering with metal chips on an α-Fe2O3 target

NASA Astrophysics Data System (ADS)

Abe, Seishi; Watanabe, Masato

2017-07-01

A simple technique that uses radio-frequency sputtering with a functional element on a hematite (α-Fe2O3) target is presented for the production of maghemite (γ-Fe2O3) thin films. These films are prepared on water-cooled glass substrates in an Ar atmosphere. Investigations are done with Ti, Si, Al, Cu, Mo, and Zn, with γ-Fe2O3 being obtained only in the presence of Cu, indicating that phase transition occurs only for this metal. Mössbauer spectra and magnetization analysis reveal that the quality of the obtained γ-Fe2O3 films is higher than that of the film produced using Mg, which was reported in our previous work. High-angle annular dark-field scanning tunneling electron microscopy and electron energy-loss spectroscopy reveal that the added Cu remains in a metallic state (without oxidization), forming a Cu/γ-Fe2O3 phase-mixture in the as-deposited film. The Cu/γ-Fe2O3 composite film exhibits negative magnetoresistance (MR), with a MR ratio of approximately 0.6% at room temperature in an applied field of 10 kOe, and a negative Faraday rotation of -5708 deg cm-1 at 830 nm.

Cryptococcus neoformans Iron-Sulfur Protein Biogenesis Machinery Is a Novel Layer of Protection against Cu Stress.

PubMed

Garcia-Santamarina, Sarela; Uzarska, Marta A; Festa, Richard A; Lill, Roland; Thiele, Dennis J

2017-10-31

Copper (Cu) ions serve as catalytic cofactors to drive key biochemical processes, and yet Cu levels that exceed cellular homeostatic control capacity are toxic. The underlying mechanisms for Cu toxicity are poorly understood. During pulmonary infection by the fungal pathogen Cryptococcus neoformans , host alveolar macrophages compartmentalize Cu to the phagosome, and the ability to detoxify Cu is critical for its survival and virulence. Here, we report that iron-sulfur (Fe-S) clusters are critical targets of Cu toxicity in both Saccharomyces cerevisiae and C. neoformans in a manner that depends on the accessibility of Cu to the Fe-S cofactor. To respond to this Cu-dependent Fe-S stress, C. neoformans induces the transcription of mitochondrial ABC transporter Atm1, which functions in cytosolic-nuclear Fe-S protein biogenesis in response to Cu and in a manner dependent on the Cu metalloregulatory transcription factor Cuf1. As Atm1 functions in exporting an Fe-S precursor from the mitochondrial matrix to the cytosol, C. neoformans cells depleted for Atm1 are sensitive to Cu even while the Cu-detoxifying metallothionein proteins are highly expressed. We provide evidence for a previously unrecognized microbial defense mechanism to deal with Cu toxicity, and we highlight the importance for C. neoformans of having several distinct mechanisms for coping with Cu toxicity which together could contribute to the success of this microbe as an opportunistic human fungal pathogen. IMPORTANCE C. neoformans is an opportunistic pathogen that causes lethal meningitis in over 650,000 people annually. The severity of C. neoformans infections is further compounded by the use of toxic or poorly effective systemic antifungal agents as well as by the difficulty of diagnosis. Cu is a natural potent antimicrobial agent that is compartmentalized within the macrophage phagosome and used by innate immune cells to neutralize microbial pathogens. While the Cu detoxification machinery of C. neoformans is essential for virulence, little is known about the mechanisms by which Cu kills fungi. Here we report that Fe-S cluster-containing proteins, including members of the Fe-S protein biogenesis machinery itself, are critical targets of Cu toxicity and therefore that this biosynthetic process provides an important layer of defense against high Cu levels. Given the role of Cu ionophores as antimicrobials, understanding how Cu is toxic to microorganisms could lead to the development of effective, broad-spectrum antimicrobials. Moreover, understanding Cu toxicity could provide additional insights into the pathophysiology of human diseases of Cu overload such as Wilson's disease. Copyright © 2017 Garcia-Santamarina et al.

Speciation and distribution of copper in a mining soil using multiple synchrotron-based bulk and microscopic techniques.

PubMed

Yang, Jianjun; Liu, Jin; Dynes, James J; Peak, Derek; Regier, Tom; Wang, Jian; Zhu, Shenhai; Shi, Jiyan; Tse, John S

2014-02-01

Molecular-level understanding of soil Cu speciation and distribution assists in management of Cu contamination in mining sites. In this study, one soil sample, collected from a mining site contaminated since 1950s, was characterized complementarily by multiple synchrotron-based bulk and spatially resolved techniques for the speciation and distribution of Cu as well as other related elements (Fe, Ca, Mn, K, Al, and Si). Bulk X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that soil Cu was predominantly associated with Fe oxides instead of soil organic matter. This agreed with the closest association of Cu to Fe by microscopic X-ray fluorescence (U-XRF) and scanning transmission X-ray microscopy (STXM) nanoanalysis, along with the non-occurrence of photoreduction of soil Cu(II) by quick Cu L3,2-edge XANES spectroscopy (Q-XANES) which often occurs when Cu organic complexes are present. Furthermore, bulk-EXAFS and STXM-coupled Fe L3,2-edge nano-XANES analysis revealed soil Cu adsorbed primarily to Fe(III) oxides by inner-sphere complexation. Additionally, Cu K-edge μ-XANES, L3,2-edge bulk-XANES, and successive Q-XANES results identified the presence of Cu2S rather than radiation-damage artifacts dominant in certain microsites of the mining soil. This study demonstrates the great benefits in use of multiple combined synchrotron-based techniques for comprehensive understanding of Cu speciation in heterogeneous soil matrix, which facilitates our prediction of Cu reactivity and environmental fate in the mining site.

Mineralogical and chemical characterization of iron-, manganese-, and copper-containing synthetic hydroxyapatites.

PubMed

Sutter, B; Ming, D W; Clearfield, A; Hossner, L R

2003-01-01

The National Aeronautics and Space Administration's (NASA) Advanced Life Support (ALS) Program is evaluating the use of Fe-, Mn-, and Cu-containing synthetic hydroxyapatite (SHA) as a slow release fertilizer for crops that might be grown on the International Space Station or at Lunar and Martian outposts. Separate Fe-, Mn-, and Cu-containing SHA materials along with a transition-metal free SHA (pure-SHA) were synthesized using a precipitation method. Chemical and mineralogical analyses determined if and how Fe, Mn, and Cu were incorporated into the SHA structure. X-ray diffraction (XRD), Rietveld refinement, and transmission electron microscopy (TEM) confirmed that SHA materials with the apatite structure were produced. Chemical analyses indicated that the metal containing SHA materials were deficient in Ca relative to pure-SHA. The shift in the infrared PO4-mu 3 vibrations, smaller unit cell parameters, smaller particle size, and greater structural strain for Fe-, Mn-, and Cu-containing SHA compared with pure-SHA suggested that Fe, Mn, and Cu were incorporated into SHA structure. Rietveld analyses revealed that Fe, Mn, and Cu substituted into the Ca2 site of SHA. An Fe-rich phase was detected by TEM analyses and backscattered electron microscopy in the Fe-containing SHA material with the greatest Fe content. The substitution of metals into SHA suggests that metal-SHA materials are potential slow-release sources of micronutrients for plant uptake in addition to Ca and P.

Mineralogical and chemical characterization of iron-, manganese-, and copper-containing synthetic hydroxyapatites

NASA Technical Reports Server (NTRS)

Sutter, B.; Ming, D. W.; Clearfield, A.; Hossner, L. R.

2003-01-01

The National Aeronautics and Space Administration's (NASA) Advanced Life Support (ALS) Program is evaluating the use of Fe-, Mn-, and Cu-containing synthetic hydroxyapatite (SHA) as a slow release fertilizer for crops that might be grown on the International Space Station or at Lunar and Martian outposts. Separate Fe-, Mn-, and Cu-containing SHA materials along with a transition-metal free SHA (pure-SHA) were synthesized using a precipitation method. Chemical and mineralogical analyses determined if and how Fe, Mn, and Cu were incorporated into the SHA structure. X-ray diffraction (XRD), Rietveld refinement, and transmission electron microscopy (TEM) confirmed that SHA materials with the apatite structure were produced. Chemical analyses indicated that the metal containing SHA materials were deficient in Ca relative to pure-SHA. The shift in the infrared PO4-mu 3 vibrations, smaller unit cell parameters, smaller particle size, and greater structural strain for Fe-, Mn-, and Cu-containing SHA compared with pure-SHA suggested that Fe, Mn, and Cu were incorporated into SHA structure. Rietveld analyses revealed that Fe, Mn, and Cu substituted into the Ca2 site of SHA. An Fe-rich phase was detected by TEM analyses and backscattered electron microscopy in the Fe-containing SHA material with the greatest Fe content. The substitution of metals into SHA suggests that metal-SHA materials are potential slow-release sources of micronutrients for plant uptake in addition to Ca and P.

Copper(II) cyanido-bridged bimetallic nitroprusside-based complexes: Syntheses, X-ray structures, magnetic properties, {sup 57}Fe Moessbauer spectroscopy and thermal studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Travnicek, Zdenek, E-mail: zdenek.travnicek@upol.c; Herchel, Radovan; Mikulik, Jiri

2010-05-15

Three heterobimetallic cyanido-bridged copper(II) nitroprusside-based complexes of the compositions [Cu(tet)Fe(CN){sub 5}NO].H{sub 2}O (1), where tet=N,N'-bis(3-aminopropyl)ethylenediamine, [Cu(hto)Fe(CN){sub 5}NO].2H{sub 2}O (2), where hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1{sup 6,9}]octadecane and [Cu(nme){sub 2}Fe(CN){sub 5}NO].H{sub 2}O (3), where nme=N-methylethylenediamine, were synthesized and characterized by elemental analyses, {sup 57}Fe Moessbauer and FTIR spectroscopies, thermal analysis, magnetic measurements and single-crystal X-ray analysis. The products of thermal degradation processes of 2 and 3 were studied by XRD, {sup 57}Fe Moessbauer spectroscopy, SEM and EDS, and they were identified as mixtures of CuFe{sub 2}O{sub 4} and CuO. - Three heterobimetallic cyano-bridged copper(II) nitroprusside-based complexes of the general compositions of [Cu(L)Fe(CN){sub 5}NO].xH{sub 2}O, wheremore » L=N,N'-bis(3-aminopropyl)ethylenediamine (complex 1), 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1{sup 6,9}]-octadecane (complex 2) and N-methylethylenediamine (complex 3), were synthesized, and fully structurally and magnetically characterized. SEM, EDS, XRD and {sup 57}Fe Moessbauer experiments were used for characterization of thermal decomposition products of complexes 2 and 3.« less

Corrosion and protection of heterogeneous cast Al-Si (356) and Al-Si-Cu-Fe (380) alloys by chromate adn cerium inhibitors

NASA Astrophysics Data System (ADS)

Jain, Syadwad

In this study, the localized corrosion and conversion coating on cast alloys 356 (Al-7.0Si-0.3Mg) and 380 (Al-8.5Si-3.5Cu-1.6Fe) were characterized. The intermetallic phases presence in the permanent mold cast alloy 356 are primary-Si, Al5FeSi, Al8Si6Mg3Fe and Mg2Si. The die cast alloy 380 is rich in Cu and Fe elements. These alloying elements result in formation of the intermetallic phases Al 5FeSi, Al2Cu and Al(FeCuCr) along with primary-Si. The Cu- and Fe-rich IMPS are cathodic with respect to the matrix phase and strongly govern the corrosion behavior of the two cast alloys in an aggressive environment due to formation of local electrochemical cell in their vicinity. Results have shown that corrosion behavior of permanent mould cast alloy 356 is significantly better than the die cast aluminum alloy 380, primarily due to high content of Cu- and Fe-rich phases such as Al2Cu and Al 5FeSi in the latter. The IMPS also alter the protection mechanism of the cast alloys in the presence of inhibitors in an environment. The presence of chromate in the solution results in reduced cathodic activity on all the phases. Chromate provides some anodic inhibition by increasing pitting potentials and altering corrosion potentials for the phases. Results have shown that performance of CCC was much better on 356 than on 380, primarily due to inhomogeneous and incomplete coating deposition on Cu- and Fe- phases present in alloy 380. XPS and Raman were used to characterize coating deposition on intermetallics. Results show evidence of cyanide complex formation on the intermetallic phases. The presence of this complex is speculated to locally suppress CCC formation. Formation and breakdown of cerium conversion coatings on 356 and 380 was also analyzed. Results showed that deposition of cerium hydroxide started with heavy precipitation on intermetallic particles with the coatings growing outwards onto the matrix. Electrochemical analysis of synthesized intermetallics compounds in the presence of soluble cerium cations showed that of anodic and cathodic activity was not as strongly inhibited as was observed for chromate ions. Overall cerium conversion coating showed good performance on Al-Si (356) ally, but poor performance on Fe- and Cu-rich alloy (380).

Iron and copper as virulence modulators in human fungal pathogens.

PubMed

Ding, Chen; Festa, Richard A; Sun, Tian-Shu; Wang, Zhan-You

2014-07-01

Fungal pathogens have evolved sophisticated machinery to precisely balance the fine line between acquiring essential metals and defending against metal toxicity. Iron and copper are essential metals for many processes in both fungal pathogens and their mammalian hosts, but reduce viability when present in excess. However, during infection, the host uses these two metals differently. Fe has a long-standing history of influencing virulence in pathogenic fungi, mostly in regards to Fe acquisition. Numerous studies demonstrate the requirement of the Fe acquisition pathway of Candida, Cryptococcus and Aspergillus for successful systemic infection. Fe is not free in the host, but is associated with Fe-binding proteins, leading fungi to develop mechanisms to interact with and to acquire Fe from these Fe-bound proteins. Cu is also essential for cell growth and development. Essential Cu-binding proteins include Fe transporters, superoxide dismutase (SOD) and cytochrome c oxidase. Although Cu acquisition plays critical roles in fungal survival in the host, recent work has revealed that Cu detoxification is extremely important. Here, we review fungal responses to altered metal conditions presented by the host, contrast the roles of Fe and Cu during infection, and outline the critical roles of fungal metal homeostasis machinery at the host-pathogen axis. © 2014 John Wiley & Sons Ltd.

Apparently enhanced magnetization of Cu(I)-modified γ-Fe2O3 based nanoparticles

NASA Astrophysics Data System (ADS)

Qiu, Xiaoyan; He, Zhenghong; Mao, Hong; Zhang, Ting; Lin, Yueqiang; Liu, Xiaodong; Li, Decai; Meng, Xiangshen; Li, Jian

2017-11-01

Using a chemically induced transition method in FeCl2 solution, γ-Fe2O3 based magnetic nanoparticles, in which γ-Fe2O3 crystallites were coated with FeCl3ṡ6H2O, were prepared. During the synthesis of the γ-Fe2O3 nanoparticles Cu(I) modification of the particles was attempted. According to the results from both magnetization measurements and structural characterization, it was judged that a magnetic silent "dead layer", which can be attributed to spin disorder in the surface of the γ-Fe2O3 crystallites due to breaking of the crystal symmetry, existed in the unmodified particles. For the Cu(I)-modified sample, the CuCl thin layer on the γ-Fe2O3 crystallites incurred the crystal symmetry to reduce the spin disorder, which "awakened" the "dead layer" on the surface of the γ-Fe2O3 crystallites, enhancing the apparent magnetization of the Cu(I)-modified nanoparticles. It was determined that the surface spin disorder of the magnetic crystallite could be related to the coating layer on the crystallite, and can be modified by altering the coating layer to enhance the effective magnetization of the magnetic nanoparticles.

Stability of the 1144 phase in iron pnictides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, B. Q.; Nguyen, Manh Cuong; Wang, C. Z.

A series of iron arsenides (e.g., CaRbFe 4As 4, SrCsFe 4As 4) have been discovered recently, and have provoked a rise in superconductor searches in a different phase, known as the 1144 phase. For the presence of various chemical substitutions, it is believed that more 1144 compounds remain to be discovered. Here in this work, we perform general model analysis as well as scenario calculation on a basis of density functional theory to investigate phase stability in a variety of compounds. We predict that the 1144-type phase could be stabilized in EuKFe 4As 4, EuRbFe 4As 4, EuCsFe 4As 4,more » CaCsFe 4P 4, SrCsFe 4P 4, BaCsFe 4P 4, InCaFe 4As 4, InSrFe 4As 4, etc. Remarkably, it involves rare earths, trivalence elements (e.g., indium) and iron phosphides, which greatly expands the range of its existence and suggests a promising prospect for experimental synthesis. In addition, we find that the formation of many random doping compounds (e.g., Ba 0.5Cs 0.5Fe 2As 2, Ba 0.5 Rb 0.5Fe 2As 2) is driven by entropy and could be annealed to a 1144-type phase. Eventually, we plot a phase diagram about two structural factors Δa and Δc, giving a bird's-eye view of stability of various 1144 compounds.« less

Stability of the 1144 phase in iron pnictides

DOE PAGES

Song, B. Q.; Nguyen, Manh Cuong; Wang, C. Z.; ...

2018-03-14

A series of iron arsenides (e.g., CaRbFe 4As 4, SrCsFe 4As 4) have been discovered recently, and have provoked a rise in superconductor searches in a different phase, known as the 1144 phase. For the presence of various chemical substitutions, it is believed that more 1144 compounds remain to be discovered. Here in this work, we perform general model analysis as well as scenario calculation on a basis of density functional theory to investigate phase stability in a variety of compounds. We predict that the 1144-type phase could be stabilized in EuKFe 4As 4, EuRbFe 4As 4, EuCsFe 4As 4,more » CaCsFe 4P 4, SrCsFe 4P 4, BaCsFe 4P 4, InCaFe 4As 4, InSrFe 4As 4, etc. Remarkably, it involves rare earths, trivalence elements (e.g., indium) and iron phosphides, which greatly expands the range of its existence and suggests a promising prospect for experimental synthesis. In addition, we find that the formation of many random doping compounds (e.g., Ba 0.5Cs 0.5Fe 2As 2, Ba 0.5 Rb 0.5Fe 2As 2) is driven by entropy and could be annealed to a 1144-type phase. Eventually, we plot a phase diagram about two structural factors Δa and Δc, giving a bird's-eye view of stability of various 1144 compounds.« less

Stability of the 1144 phase in iron pnictides

NASA Astrophysics Data System (ADS)

Song, B. Q.; Nguyen, Manh Cuong; Wang, C. Z.; Ho, K. M.

2018-03-01

A series of iron arsenides (e.g., CaRbFe4As4 , SrCsFe4As4 ) have been discovered recently, and have provoked a rise in superconductor searches in a different phase, known as the 1144 phase. For the presence of various chemical substitutions, it is believed that more 1144 compounds remain to be discovered. In this work, we perform general model analysis as well as scenario calculation on a basis of density functional theory to investigate phase stability in a variety of compounds. We predict that the 1144-type phase could be stabilized in EuKFe4As4 , EuRbFe4As4 , EuCsFe4As4 , CaCsFe4P4 , SrCsFe4P4 , BaCsFe4P4 , InCaFe4As4 , InSrFe4As4 , etc. Remarkably, it involves rare earths, trivalence elements (e.g., indium) and iron phosphides, which greatly expands the range of its existence and suggests a promising prospect for experimental synthesis. In addition, we find that the formation of many random doping compounds (e.g., Ba0.5Cs0.5Fe2As2 , Ba0.5Rb0.5Fe2As2 ) is driven by entropy and could be annealed to a 1144-type phase. Eventually, we plot a phase diagram about two structural factors Δ a and Δ c , giving a bird's-eye view of stability of various 1144 compounds.

Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate

DOE PAGES

Ojwang, Dickson O.; Grins, Jekabs; Wardecki, Dariusz; ...

2016-06-03

Copper hexacyanoferrate, Cu II[Fe III(CN) 6] 2/3 nH 2O, was synthesized, and varied amounts of K + ions were inserted via reduction by K 2S 2O 3 (aq). Ideally, the reaction can be written as Cu II[Fe III(CN) 6] 2/3∙ nH 2O + 2x/3K + + 2x/3e⁻ ↔K 2x/3Cu II[Fe II xFe III 1- x(CN) 6] 2/3 nH 2O. Infrared, Raman, and Mössbauer spectroscopy studies show that Fe III is continuously reduced to Fe II with increasing x, accompanied by a decrease of the a-axis of the cubic Fmore » $$m\\bar{3}$$m unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction, ~20% of the Fe III, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of ~26 wt % upon heating to 180 °C, above which the structure starts to decompose. The crystal structures of Cu II[Fe III(CN) 6] 2/3∙ nH 2O and K 2/3Cu[Fe(CN) 6] 2/3∙ nH 2O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN) 6 groups are vacant, and the octahedron around Cu II is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the Cu N C Fe framework. In conclusion, the K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K + ions.« less

Europium-engineered iron oxide nanocubes with high T1 and T2 contrast abilities for MRI in living subjects

NASA Astrophysics Data System (ADS)

Yang, Lijiao; Zhou, Zijian; Liu, Hanyu; Wu, Changqiang; Zhang, Hui; Huang, Guoming; Ai, Hua; Gao, Jinhao

2015-04-01

Magnetic resonance imaging (MRI) contrast agents with both positive (T1) and negative (T2) contrast abilities are needed in clinical diagnosis for fault-free accurate detection of lesions. We report a facile synthesis of europium-engineered iron oxide (EuIO) nanocubes as T1 and T2 contrast agents for MRI in living subjects. The Eu(iii) oxide-embedded iron oxide nanoparticles significantly increase the T1 relaxivity with an enhanced positive contrast effect. EuIO nanocubes with 14 nm in diameter showed a high r1 value of 36.8 mM-1 s-1 with respect to total metal ions (Fe + Eu), which is about 3 times higher than that of Fe3O4 nanoparticles with similar size. Moreover, both r1 and r2 values of EuIO nanocubes can be tuned by varying their sizes and Eu doping ratios. After citrate coating, EuIO nanocubes can provide enhanced T1 and T2 contrast effects in small animals, particularly in the cardiac and liver regions. This work may provide an insightful strategy to design MRI contrast agents with both positive and negative contrast abilities for biomedical applications.Magnetic resonance imaging (MRI) contrast agents with both positive (T1) and negative (T2) contrast abilities are needed in clinical diagnosis for fault-free accurate detection of lesions. We report a facile synthesis of europium-engineered iron oxide (EuIO) nanocubes as T1 and T2 contrast agents for MRI in living subjects. The Eu(iii) oxide-embedded iron oxide nanoparticles significantly increase the T1 relaxivity with an enhanced positive contrast effect. EuIO nanocubes with 14 nm in diameter showed a high r1 value of 36.8 mM-1 s-1 with respect to total metal ions (Fe + Eu), which is about 3 times higher than that of Fe3O4 nanoparticles with similar size. Moreover, both r1 and r2 values of EuIO nanocubes can be tuned by varying their sizes and Eu doping ratios. After citrate coating, EuIO nanocubes can provide enhanced T1 and T2 contrast effects in small animals, particularly in the cardiac and liver regions. This work may provide an insightful strategy to design MRI contrast agents with both positive and negative contrast abilities for biomedical applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00774g

Interfacial Microstructure and Its Influence on Resistivity of Thin Layers Copper Cladding Steel Wires

NASA Astrophysics Data System (ADS)

Li, Hongjuan; Ding, Zhimin; Zhao, Ruirong

2018-04-01

The interfacial microstructure and resistivity of cold-drawn and annealed thin layers copper cladding steel (CCS) wires have been systematically investigated by the methods of scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and resistivity testing. The results showed that the Cu and Fe atoms near interface diffused into each other matrixes. The Fe atoms diffused into Cu matrixes and formed a solid solution. The mechanism of solid solution is of substitution type. When the quantity of Fe atoms exceeds the maximum solubility, the supersaturated solid solution would form Fe clusters and decompose into base Cu and α-Fe precipitated phases under certain conditions. A few of α-Fe precipitates was observed in the copper near Cu/Fe interfaces of cold-drawn CCS wires, with 1-5 nm in size. A number of α-Fe precipitates of 1-20 nm in size can be detected in copper near Cu/Fe interfaces of CCS wires annealed at 850°C. When annealing temperature was less than 750°C, the resistivity of CCS wires annealed was lower than that of cold-drawn CCS wires. However, when annealing temperature was above 750°C, the resistivity of CCS wires was greater than that of cold-drawn CCS wires and increased with rising the annealing temperature. The relationship between nanoscale α-Fe precipitation and resistivity of CCS wires has been well discussed.

Luminescence properties of pure and doped CaSO4 nanorods irradiated by 15 MeV e-beam

NASA Astrophysics Data System (ADS)

Salah, Numan; Alharbi, Najlaa D.; Enani, Mohammad A.

2014-01-01

Calcium sulfate (CaSO4) doped with proper activators is a highly sensitive phosphor used in different fields mainly for radiation dosimetry, lighting and display applications. In this work pure and doped nanorods of CaSO4 were produced by the co-precipitation technique. Samples from this material doped with Ag, Cu, Dy, Eu and Tb were exposed to different doses of 15 MeV e-beam and studied for their thermoluminesence (TL) and photoluminescence (PL) properties. Color center formation leading to PL emissions were investigated before and after e-beam irradiation. The samples doped with rare earths elements (i.e. Dy, Eu and Tb) were observed to have thinner nanorods than the other samples and have higher absorption in the UV region. The Ag and Tb doped samples have poor TL response to e-beam, while those activated by Cu, Dy and Eu have strong glow peaks at around 123 °C. Quite linear response curves in the whole studied exposures i.e. 0.1-100 Gy were also observed in Cu and Dy doped samples. The PL results show that pure CaSO4 nanorods have active color centers without irradiation, which could be enriched/modified by these impurities mainly rare earths and further enhanced by e-beam irradiation. Eu3+ → Eu2+ conversion is clearly observed in Eu doped sample after e-beam irradiation. These results show that these nanorods might be useful in lighting and display devices development.

Co-Precipitation, Strength and Electrical Resistivity of Cu–26 wt % Ag–0.1 wt % Fe Alloy

PubMed Central

Li, Rui; Wang, Engang

2017-01-01

Both a Cu–26 wt % Ag (Fe-free) alloy and Cu–26 wt % Ag–0.1 wt % Fe (Fe-doping) alloy were subjected to different heat treatments. We studied the precipitation kinetics of Ag and Cu, microstructure evolution, magnetization, hardness, strength, and electrical resistivity of the two alloys. Fe addition was incapable of changing the precipitation kinetics of Ag and Cu; however, it decreased the size and spacing of rod-shaped Ag precipitates within a Cu matrix, because Fe might affect the elastic strain field and diffusion field, suppressing the nucleation of Ag precipitates. Magnetization curves showed that γ-Fe precipitates were precipitated out of the Cu matrix, along with Ag precipitates in Fe-doping alloy after heat treatments. The yield strength of the Fe-doping alloy was higher than that of the Fe-free alloy, and the maximum increment was about 41.3%. The electrical conductivity in the aged Fe-doping alloy was up to about 67% IACS (International Annealed Copper Standard). Hardness, strength, and electrical resistivity were intensively discussed, based on the microstructural characterization and solute contributions of both alloys. Our results demonstrated that an increasing fraction of nanoscale γ-Fe precipitates and decreasing spacing between Ag precipitates resulted in the increasing strength of the Fe-doping alloy. PMID:29207505

A serials of sandwich-like trinuclear and one-dimensional chain cyanide-bridged iron(III)-copper(II) complexes: Syntheses, crystal structures and magnetic properties

NASA Astrophysics Data System (ADS)

Shi, Jingwen; Lan, Wenlong; Ren, Yanjie; Liu, Qingyun; Liu, Hui; Dong, Yunhui; Zhang, Daopeng

2018-04-01

Four pyridinecarboxamide trans-dicyanideiron(III) building blocks and one macrocyclic copper(II) compound have been employed to assemble cyanide-bridged heterometallic complexes, resulting in a serials of cyanide-bridged FeIII-CuII complexes with different structure types. The series of complexes can be formulated as: {[Cu(Cyclam)][Fe(bpb)(CN)2]2}·4H2O (1), {{[Cu(Cyclam)][Fe(bpb)(CN)2]}ClO4}n·nH2O (2), and {[Cu(Cyclam)][Fe(bpmb)(CN)2]2}·4H2O (3), {[Cu(Cyclam)][Fe(bpClb)(CN)2]2}·4H2O (4) and {{[Cu(Cyclam)][Fe(bpdmb)(CN)2]}ClO4}n·2nCH3OH (5) (bpb2- = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb2- = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpClb2- = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate, bpdmb2- = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate, Cyclam = 1,4,8,11-tetraazacyclotetradecane). All the complexes have been characterized by elemental analysis, IR spectra and structural determination. Single X-ray diffraction analysis shows the similar neutral sandwich-like structures for complexes 1, 3 and 4, in which the two cyano precursors acting as monodentate ligand through one of their two cyanide groups were coordinated face to face to central Cu(II) ion. The complexes 2 and 5 can be structurally characterized as one-dimensional cationic single chain consisting of alternating units of [Cu(Cyclam)]2+ and [Fe(bpb/bpdmb)(CN)2]- with free ClO4- as balanced anion. Investigation over magnetic properties of the whole serials of complexes reveals the antiferromagnetic magnetic coupling between the neighboring cyanide-bridged Fe(III) and Cu(II) ions in complexes 3 and 4 and the ferromagnetic interaction in complexes 1, 2 and 5, respectively.

The geochemical cycling of trace elements in a biogenic meromictic lake

NASA Astrophysics Data System (ADS)

Balistrieri, Laurie S.; Murray, James W.; Paul, Barbara

1994-10-01

The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d -1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn).

The geochemical cycling of trace elements in a biogenic meromictic lake

USGS Publications Warehouse

Balistrieri, L.S.; Murray, J.W.; Paul, B.

1994-01-01

The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d-1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn). ?? 1994.

Intermediate-valence state of the Sm and Eu in SmB 6 and EuCu 2 Si 2 : neutron spectroscopy data and analysis

DOE PAGES

Savchenkov, P. S.; Alekseev, P. A.; Podlesnyak, A.; ...

2018-01-11

For this study, magnetic neutron scattering data for Sm (SmB 6, Sm(Y)S) and Eu (EuCu 2Si 2- x Ge x ) intermediate-valence compounds have been analysed in terms of a generalized model of the intermediate-radius exciton. Special attention is paid to the correlation between the average ion's valence and parameters of the low-energy excitation in the neutron spectra, such as the resonance mode, including its magnetic form factor. Along with specific features of the formation of the intermediate-valence state for Sm and Eu ions, common physical mechanisms have been revealed for systems based on these elements from the middle ofmore » the rare-earth series. A consistent description of the existing experimental data has been obtained by using the concept of a loosely bound hole for the Eu f-electron shell in the intermediate-valence state, in analogy with the previously established loosely bound electron model for the Sm ion.« less

Intermediate-valence state of the Sm and Eu in SmB 6 and EuCu 2 Si 2 : neutron spectroscopy data and analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savchenkov, P. S.; Alekseev, P. A.; Podlesnyak, A.

For this study, magnetic neutron scattering data for Sm (SmB 6, Sm(Y)S) and Eu (EuCu 2Si 2- x Ge x ) intermediate-valence compounds have been analysed in terms of a generalized model of the intermediate-radius exciton. Special attention is paid to the correlation between the average ion's valence and parameters of the low-energy excitation in the neutron spectra, such as the resonance mode, including its magnetic form factor. Along with specific features of the formation of the intermediate-valence state for Sm and Eu ions, common physical mechanisms have been revealed for systems based on these elements from the middle ofmore » the rare-earth series. A consistent description of the existing experimental data has been obtained by using the concept of a loosely bound hole for the Eu f-electron shell in the intermediate-valence state, in analogy with the previously established loosely bound electron model for the Sm ion.« less

Atomistic Simulations of Grain Boundary Pinning in CuFe Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zepeda-Ruiz, L A; Gilmer, G H; Sadigh, B

2005-05-22

The authors apply a hybrid Monte Carlo-molecular dynamics code to the study of grain boundary motion upon annealing of pure Cu and Cu with low concentrations of Fe. The hybrid simulations account for segregation and precipitation of the low solubility Fe, together with curvature driven grain boundary motion. Grain boundaries in two different systems, a {Sigma}7+U-shaped half-loop grain and a nanocrystalline sample, were found to be pinned in the presence of Fe concentrations exceeding 3%.

Irreversibility and critical current density of FeSr2ErCu2O6+y

NASA Astrophysics Data System (ADS)

Hata, Y.; Iida, I.; Mochiku, T.; Yasuoka, H.

2018-03-01

FeSr2ErCu2O6+y (ErFe1212) and non-superconducting FeSr2ErCu1.9Zn0.1O6+y were synthesized to study the property of the superconductivity and the irreversibility of ErFe1212. A large irreversibility in the temperature dependence of magnetization and a hysteresis in the magnetization curve were observed in ErFe1212. By comparison with non-superconducting FeSr2ErCu1.9Zn0.1O6+y, it was found that the most part of the hysteresis at high magnetic eld originates from the magnetism of Fe ion and some part of the hysteresis at low magnetic eld originates from the superconductivity. Using the magnetization curve of ErFe1212 and FeSr2ErCu1.9Zn0.1O6+y, the J c of ErFe1212 in individual grains at 10 K under 0.1 T was estimated by the Bean model and {J}\\text{c}\\text{intra} was 2.6 × 109 A/m2. The critical current density across inter-grain boundaries at 10 K estimated by V ‑ I measurement was {J}\\text{c}\\text{intra} = 5.7 × 104 A/m2. A large difference between {J}\\text{c}\\text{intra} and {J}\\text{c}\\text{intra} was observed in ErFe1212. {J}\\text{c}\\text{intra} and {J}\\text{c}\\text{intra} of ErFe1212 are 2.2 and 5.2 times larger than these of YFe1212, respectively.

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

PubMed Central

Zhang, Bing-Qian; Zuo, Yong; Chen, Jing-Shuai; Niu, He-Lin; Mao, Chang-Jie

2017-01-01

Copper-based chalcogenides that contain abundant, low-cost and environmentally-friendly elements, are excellent materials for numerous energy conversion applications, such as photocatalysis, photovoltaics, photoelectricity and thermoelectrics (TE). Here, we present a high-yield and upscalable colloidal synthesis route for the production of monodisperse ternary I-III-VI2 chalcogenides nanocrystals (NCs), particularly stannite CuFeSe2, with uniform shape and narrow size distributions by using selenium powder as the anion precursor and CuCl2·2H2O and FeCl3 as the cationic precursors. The composition, the state of valence, size and morphology of the CuFeSe2 materials were examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM), respectively. Furthermore, the TE properties characterization of these dense nanomaterials compacted from monodisperse CuFeSe2 NCs by hot press at 623 K were preliminarily studied after ligand removal by means of hydrazine and hexane solution. The TE performances of the sintered CuFeSe2 pellets were characterized in the temperature range from room temperature to 653 K. Finally, the dimensionless TE figure of merit (ZT) of this Earth-abundant and intrinsic p-type CuFeSe2 NCs is significantly increased to 0.22 at 653 K in this work, which is demonstrated to show a promising TE materialand makes it a possible p-type candidate for medium-temperature TE applications. PMID:29278381

Redox chemistry of a binary transition metal oxide (AB 2 O 4 ): a study of the Cu 2+ /Cu 0 and Fe 3+ /Fe 0 interconversions observed upon lithiation in a CuFe 2 O 4 battery using X-ray absorption spectroscopy

DOE PAGES

Cama, Christina A.; Pelliccione, Christopher J.; Brady, Alexander B.; ...

2016-06-06

Copper ferrite, CuFe 2 O 4, is a promising candidate for application as a high energy electrode material in lithium based batteries. Mechanistic insight on the electrochemical reduction and oxidation processes was gained through the first X-ray absorption spectroscopic study of lithiation and delithiation of CuFe 2 O 4. A phase pure tetragonal CuFe 2 O 4 material was prepared and characterized using laboratory and synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. We used ex situ X-ray absorption spectroscopy (XAS) measurements to study the battery redox processes at the Fe and Cu K-edges, using X-ray absorption near-edge structuremore » (XANES), extended X-ray absorption fine structure (EXAFS), and transmission X-ray microscopy (TXM) spectroscopies. EXAFS analysis showed upon discharge, an initial conversion of 50% of the copper(II) to copper metal positioned outside of the spinel structure, followed by a migration of tetrahedral iron(III) cations to octahedral positions previously occupied by copper(II). Then, upon charging to 3.5 V, the copper metal remained in the metallic state, while iron metal oxidation to iron(III) was achieved. Our results provide new mechanistic insight regarding the evolution of the local coordination environments at the iron and copper centers upon discharging and charging.« less

Composite CuFe1 - xSnxO2/p-type silicon photodiodes

NASA Astrophysics Data System (ADS)

Al-Sehemi, Abdullah G.; Mensah-Darkwa, K.; Al-Ghamdi, Ahmed A.; Soylu, M.; Gupta, R. K.; Yakuphanoglu, F.

2017-06-01

CuFe1 - xSnxO2 composite thin film/p-type silicon diodes were prepared on substrate by sol-gel method (x = 0.00, 0.01, 0.03, 0.05, 0.07). The structure of CuFe1 - xSnxO2 composite thin films was studied using XRD analysis and films exhibited amorphous behavior. The elemental compositions and surface morphology of the films were characterized using SEM and EDX. EDX results confirmed the presence of the compositional elements. The optical band gap of CuFe1 - xSnxO2 composite thin films was determined using the optic spectra. The optical band gaps of the CuFe1 - xSnxO2 composite thin films were calculated using optical data and were found to be 3.75, 3.78, 3.80, 3.85 and 3.83 eV for x = 0.00, 0.01, 0.03, 0.05 and 0.07, respectively. The photoresponse and electrical properties of the Al/CuFe1 - xSnxO2/p-Si/Al diode were studied. The barrier height and ideality factor were determined to be averagely 0.67 eV and 2.6, respectively. The electrical and photoresponse characteristics of the diodes have been investigated under dark and solar light illuminations, respectively. The interface states were used to explain the results obtained in present study. CuFe1 - xSnxO2 photodiodes exhibited a high photoresponsivity to be used in optoelectronic applications.

Redox chemistry of a binary transition metal oxide (AB2O4): a study of the Cu(2+)/Cu(0) and Fe(3+)/Fe(0) interconversions observed upon lithiation in a CuFe2O4 battery using X-ray absorption spectroscopy.

PubMed

Cama, Christina A; Pelliccione, Christopher J; Brady, Alexander B; Li, Jing; Stach, Eric A; Wang, Jiajun; Wang, Jun; Takeuchi, Esther S; Takeuchi, Kenneth J; Marschilok, Amy C

2016-06-22

Copper ferrite, CuFe2O4, is a promising candidate for application as a high energy electrode material in lithium based batteries. Mechanistic insight on the electrochemical reduction and oxidation processes was gained through the first X-ray absorption spectroscopic study of lithiation and delithiation of CuFe2O4. A phase pure tetragonal CuFe2O4 material was prepared and characterized using laboratory and synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Ex situ X-ray absorption spectroscopy (XAS) measurements were used to study the battery redox processes at the Fe and Cu K-edges, using X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and transmission X-ray microscopy (TXM) spectroscopies. EXAFS analysis showed upon discharge, an initial conversion of 50% of the copper(ii) to copper metal positioned outside of the spinel structure, followed by a migration of tetrahedral iron(iii) cations to octahedral positions previously occupied by copper(ii). Upon charging to 3.5 V, the copper metal remained in the metallic state, while iron metal oxidation to iron(iii) was achieved. The results provide new mechanistic insight regarding the evolution of the local coordination environments at the iron and copper centers upon discharging and charging.

Greener Route for Synthesis of aryl and alkyl-14H-dibenzo [a.j] xanthenes using Graphene Oxide-Copper Ferrite Nanocomposite as a Recyclable Heterogeneous Catalyst

NASA Astrophysics Data System (ADS)

Kumar, Aniket; Rout, Lipeeka; Achary, Lakkoji Satish Kumar; Dhaka, Rajendra. S.; Dash, Priyabrat

2017-02-01

A facile, efficient and environmentally-friendly protocol for the synthesis of xanthenes by graphene oxide based nanocomposite (GO-CuFe2O4) has been developed by one-pot condensation route. The nanocomposite was designed by decorating copper ferrite nanoparticles on graphene oxide (GO) surface via a solution combustion route without the use of template. The as-synthesized GO-CuFe2O4 composite was comprehensively characterized by XRD, FTIR, Raman, SEM, EDX, HRTEM with EDS mapping, XPS, N2 adsorption-desorption and ICP-OES techniques. This nanocomposite was then used in an operationally simple, cost effective, efficient and environmentally benign synthesis of 14H-dibenzo xanthene under solvent free condition. The present approach offers several advantages such as short reaction times, high yields, easy purification, a cleaner reaction, ease of recovery and reusability of the catalyst by a magnetic field. Based upon various controlled reaction results, a possible mechanism for xanthene synthesis over GO-CuFe2O4 catalyst was proposed. The superior catalytic activity of the GO-CuFe2O4 nanocomposite can be attributed to the synergistic interaction between GO and CuFe2O4 nanoparticles, high surface area and presence of small sized CuFe2O4 NPs. This versatile GO-CuFe2O4 nanocomposite synthesized via combustion method holds great promise for applications in wide range of industrially important catalytic reactions.

Efficient solar light-driven degradation of Congo red with novel Cu-loaded Fe3O4@TiO2 nanoparticles.

PubMed

Arora, Priya; Fermah, Alisha; Rajput, Jaspreet Kaur; Singh, Harminder; Badhan, Jigyasa

2017-08-01

In this work, Cu-loaded Fe 3 O 4 @TiO 2 core shell nanoparticles were prepared in a single pot by coating of TiO 2 on Fe 3 O 4 nanoparticles followed by Cu loading. X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), thermogravimetric analysis (TGA), Brunauer-Emmett- Teller (BET), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and valence band X-ray photoelectron spectroscopy (VB XPS) techniques were used for characterization of as prepared nanoparticles. Synergism between copper and titania was evaluated by studying the solar light-driven photodegradation of Congo red dye solution in the presence of Fe 3 O 4 @TiO 2 nanoparticles on one side and Cu-loaded Fe 3 O 4 @TiO 2 nanoparticles on the other side. The latter performed better than the former catalyst, indicating the enhanced activity of copper-loaded catalyst. Further photodegradation was studied by three means, i.e., under ultraviolet (UV), refluxing, and solar radiations. Cu-loaded Fe 3 O 4 @TiO 2 enhanced the degradation efficiency of Congo red dye. Thus, Cu act possibly by reducing the band gap of TiO 2 and widening the optical response of semiconductor, as a result of which solar light could be used to carry out photocatalysis. Graphical abstract Photodegradation of congo red over Cu-loaded Fe 3 O 4 @TiO 2 nanoparticles.

One-step assembly of Fe(III)-CMC chelate hydrogel onto nanoneedle-like CuO@Cu membrane with superhydrophilicity for oil-water separation

NASA Astrophysics Data System (ADS)

Dai, Jiangdong; Chang, Zhongshuai; Xie, Atian; Zhang, Ruilong; Tian, Sujun; Ge, Wenna; Yan, Yongsheng; Li, Chunxiang; Xu, Wei; Shao, Rong

2018-05-01

The research of superhydrophilic interface is developing rapidly, but the preparations of superhydrophilic surfaces through simple methods are still challenging. Herein, we reported a facile, rapid and environmentally-friendly approach for preparing a novel superhydrophilic and underwater superoleophobic membrane via the thermal oxidation of Cu mesh and one-step coordinated assembly of Fe(III)-CMC chelate hydrogel. Superhydrophilicity was attributed to the hydrophilicity of Fe(III)-CMC chelate hydrogel and nanoneedle-like rough structure of CuO@Cu membrane. The membrane was used to separate a variety of oil/water mixtures and exhibited excellent separation performance. Moreover, the membrane exhibited the excellent durability and superior stability against corrosion conditions. We envision that the Fe(III)-CMC@CuO@Cu membrane with good underwater superoleophobicity could provide a candidate not only for oil/water separation but also many other potential applications such as underwater oil manipulation, self-clean, and bio-adhesion control.

In situ study of heavy ion irradiation response of immiscible Cu/Fe multilayers

DOE PAGES

Chen, Youxing; Li, Nan; Bufford, Daniel Charles; ...

2016-04-09

By providing active defect sinks that capture and annihilate radiation induced defect clusters immiscible metallic multilayers with incoherent interfaces can effectively reduce defect density in ion irradiated metals. Although it is anticipated that defect density within the layers should vary as a function of distance to the layer interface, there is, to date, little in situ TEM evidence to validate this hypothesis. In our study monolithic Cu films and Cu/Fe multilayers with individual layer thickness, h, of 100 and 5 nm were subjected to in situ Cu ion irradiation at room temperature to nominally 1 displacement-per-atom inside a transmission electronmore » microscope. Rapid formation and propagation of defect clusters were observed in monolithic Cu, whereas fewer defects with smaller dimensions were generated in Cu/Fe multilayers with smaller h. Moreover, in situ video shows that the cumulative defect density in Cu/Fe 100 nm multilayers indeed varies, as a function of distance to the layer interfaces, supporting a long postulated hypothesis.« less

TEM study on a new Zr-(Fe, Cu) phase in furnace-cooled Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cu alloy

NASA Astrophysics Data System (ADS)

Liu, Yushun; Qiu, Risheng; Luan, Baifeng; Hao, Longlong; Tan, Xinu; Tao, Boran; Zhao, Yifan; Li, Feitao; Liu, Qing

2018-06-01

A new Zr-(Fe, Cu) phase was found in furnace-cooled Zr-1.0Sn-0.3Nb-0.3Fe- 0.1Cu alloy and alloys aged at 580 °C for 10min, 2 h and 10 h. Electron diffraction experiment shows the crystal structure of this phase to be body-centered tetragonal with unit cell dimensions determined to be a = b = 6.49 Å, c = 5.37 Å. Its possible space groups have been discussed and the reason accounting for its formation is believed to be the addition of Cu according to the atom-level images. In addition, no crystal structural or chemical composition changes were observed throughout the aging process.

Note: Erosion of W-Ni-Fe and W-Cu alloy electrodes in repetitive spark gaps.

PubMed

Wu, Jiawei; Han, Ruoyu; Ding, Weidong; Qiu, Aici; Tang, Junping

2018-02-01

A pair of W-Ni-Fe and W-Cu electrodes were tested under 100 kA level pulsed currents for 10 000 shots, respectively. Surface roughness and morphology characteristics of the two pairs of electrodes were obtained and compared. Experimental results indicated cracks divided the W-Cu electrode surface to polygons while the W-Ni-Fe electrode surface remained as a whole with pits and protrusions. Accordingly, the surface roughness of W-Ni-Fe electrodes increased to ∼3 μm while that of W-Cu electrodes reached ∼7 μm at the end of the test. The results reveal that the W-Ni-Fe alloy has a better erosion resistance and potential to be further applied in spark gaps.

Near-neighbor mixing and bond dilation in mechanically alloyed Cu-Fe

NASA Astrophysics Data System (ADS)

Harris, V. G.; Kemner, K. M.; Das, B. N.; Koon, N. C.; Ehrlich, A. E.; Kirkland, J. P.; Woicik, J. C.; Crespo, P.; Hernando, A.; Garcia Escorial, A.

1996-09-01

Extended x-ray-absorption fine-structure (EXAFS) measurements were used to obtain element-specific, structural, and chemical information of the local environments around Cu and Fe atoms in high-energy ball-milled CuxFe1-x samples (x=0.50 and 0.70). Analysis of the EXAFS data shows both Fe and Cu atoms reside in face-centered-cubic sites where the first coordination sphere consists of a mixture of Fe and Cu atoms in a ratio which reflects the as-prepared stoichiometry. The measured bond distances indicate a dilation in the bonds between unlike neighbors which accounts for the lattice expansion measured by x-ray diffraction. These results indicate that metastable alloys having a positive heat of mixing can be prepared via the high-energy ball-milling process.

The effect of Mn/Ni on thermodynamic properties of critical nucleus in Fe-Cu-Mn (Ni) ternary alloys

DOE PAGES

Li, Boyan; Zhang, Lei; Li, Chengliang; ...

2018-04-18

The aging- or radiation-induced hardening of Cu/Mn/Ni precipitates in Fe alloys is one of property degradation mechanisms in structural materials in nuclear reactors. Experiments show that aging or radiation leads the formation of Cu-rich precipitates, and the addition of Mn or Ni elements enhances the precipitation kinetics. In this study, the phase-field model coupled with the constrained string method have been applied to investigate the thermodynamic properties of critical nuclei such as the minimum energy path of Cu/Mn/Ni precipitation in Fe-Cu-Mn and Fe-Cu-Ni ternary alloys. The chemical free energies used in the model are taken from CALPHAD. The simulation resultsmore » show that the formation of Cu/Mn/Ni clusters needs to overcome an energy barrier, and the precipitate has a Core-Shell structure. The thermodynamic properties of the critical nucleus are influenced by temperature and Cu/Mn/Ni overall concentrations, which are in accordance with the simulation results as well as the experimental observations.« less

The effect of Mg-doping and Cu nonstoichiometry on the photoelectrochemical response of CuFeO 2

DOE PAGES

Wuttig, Anna; Krizan, Jason W.; Gu, Jing; ...

2016-11-14

Here, we report the tuning of CuFeO 2 photoelectrodes by Mg doping and Cu deficiency to demonstrate the effects of carrier concentration on the photoresponse. Carrier type and concentration were quantitatively assessed using the Hall effect on pure, Mg-incorporated, and Cu-deficient pellets (CuFe 1–xMg xO 2 and Cu 1–yFeO 2, x = 0, 0.0005, 0.005, 0.02, and y = 0.005, 0.02) over the range of thermodynamic stability achievable using solid-state synthesis. The same samples were used in a photoelectrochemical cell to measure their photoresponse. We find that the material with the lowest p-type carrier concentration and the highest carrier mobilitymore » shows the largest photoresponse. Furthermore, we show that increasing the p-type carrier concentration and thus the conductivity to high levels is limited by the delafossite defect chemistry, which changes the majority carrier type from p-type to n-type near the Mg solubility limit (x = 0.05) and at high Cu defect concentrations.« less

The effect of Mn/Ni on thermodynamic properties of critical nucleus in Fe-Cu-Mn (Ni) ternary alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Boyan; Zhang, Lei; Li, Chengliang

The aging- or radiation-induced hardening of Cu/Mn/Ni precipitates in Fe alloys is one of property degradation mechanisms in structural materials in nuclear reactors. Experiments show that aging or radiation leads the formation of Cu-rich precipitates, and the addition of Mn or Ni elements enhances the precipitation kinetics. In this study, the phase-field model coupled with the constrained string method have been applied to investigate the thermodynamic properties of critical nuclei such as the minimum energy path of Cu/Mn/Ni precipitation in Fe-Cu-Mn and Fe-Cu-Ni ternary alloys. The chemical free energies used in the model are taken from CALPHAD. The simulation resultsmore » show that the formation of Cu/Mn/Ni clusters needs to overcome an energy barrier, and the precipitate has a Core-Shell structure. The thermodynamic properties of the critical nucleus are influenced by temperature and Cu/Mn/Ni overall concentrations, which are in accordance with the simulation results as well as the experimental observations.« less

Optical and Piezoelectric Study of KNN Solid Solutions Co-Doped with La-Mn and Eu-Fe.

PubMed

Peña-Jiménez, Jesús-Alejandro; González, Federico; López-Juárez, Rigoberto; Hernández-Alcántara, José-Manuel; Camarillo, Enrique; Murrieta-Sánchez, Héctor; Pardo, Lorena; Villafuerte-Castrejón, María-Elena

2016-09-28

The solid-state method was used to synthesize single phase potassium-sodium niobate (KNN) co-doped with the La 3+ -Mn 4+ and Eu 3+ -Fe 3+ ion pairs. Structural determination of all studied solid solutions was accomplished by XRD and Rietveld refinement method. Electron paramagnetic resonance (EPR) studies were performed to determine the oxidation state of paramagnetic centers. Optical spectroscopy measurements, excitation, emission and decay lifetime were carried out for each solid solution. The present study reveals that doping KNN with La 3+ -Mn 4+ and Eu 3+ -Fe 3+ at concentrations of 0.5 mol % and 1 mol %, respectively, improves the ferroelectric and piezoelectric behavior and induce the generation of optical properties in the material for potential applications.

Optical and Piezoelectric Study of KNN Solid Solutions Co-Doped with La-Mn and Eu-Fe

PubMed Central

Peña-Jiménez, Jesús-Alejandro; González, Federico; López-Juárez, Rigoberto; Hernández-Alcántara, José-Manuel; Camarillo, Enrique; Murrieta-Sánchez, Héctor; Pardo, Lorena; Villafuerte-Castrejón, María-Elena

2016-01-01

The solid-state method was used to synthesize single phase potassium-sodium niobate (KNN) co-doped with the La3+–Mn4+ and Eu3+–Fe3+ ion pairs. Structural determination of all studied solid solutions was accomplished by XRD and Rietveld refinement method. Electron paramagnetic resonance (EPR) studies were performed to determine the oxidation state of paramagnetic centers. Optical spectroscopy measurements, excitation, emission and decay lifetime were carried out for each solid solution. The present study reveals that doping KNN with La3+–Mn4+ and Eu3+–Fe3+ at concentrations of 0.5 mol % and 1 mol %, respectively, improves the ferroelectric and piezoelectric behavior and induce the generation of optical properties in the material for potential applications. PMID:28773925

Electrochemical corrosion behavior, microstructure and magnetic properties of sintered Nd-Fe-B permanent magnet doped by CuZn5 powders

NASA Astrophysics Data System (ADS)

Liu, W. Q.; Wang, Z.; Sun, C.; Yue, M.; Liu, Y. Q.; Zhang, D. T.; Zhang, J. X.

2014-05-01

Nd-Fe-B permanent magnets with a small amount of CuZn5 powders doping were prepared by conventional sintered method. The effects of CuZn5 contents on magnetic properties and microstructure, electrochemical corrosion resistance of sintered Nd-Fe-B magnets were systematically studied. The results show that the magnetic properties of magnets do not have a significant variation by CuZn5 powders doping; the coercivity of magnets rises gradually, while the remanence of the magnets decreases a little with increasing of the CuZn5 amount. The CuZn5 doped magnets have more positive corrosion potential, Ecorr, and much lower corrosion current density, icorr, than the magnets without CuZn5 doping, indicating CuZn5 doping could improve the corrosion resistance. Both Zn and Cu enrich mainly into the Nd-rich phase, fully improve the wettability between the Nd-rich phase and the Nd2Fe14B phase, and repair the defects of the main phase, so the coercivity of magnets doped with CuZn5 powders rises. Such microstructure modification effectively restrains the aggressive inter-granular corrosion. As a result, the CuZn5 doped magnet possesses excellent corrosion resistance in NaCl electrolyte.

Study of a water-soluble fluorescent sensor based on the Eu(III) pefloxacin complex.

PubMed

Wen, Chaohao; Yang, Jinglian; Zeng, Zhi; Gao, Jinwei; Zheng, Yuhui

2017-05-01

The antibiotic type organic structure pefloxacin binds well with europium (III) ions as a useful scaffold for assembling optical probes and allows energy transfer from ligand to metal ions through coordination linkages. This water-soluble chemosensor demonstrated significant 'off-on (red)' changes from an alkaline to a neutral environment (pH 14-8). The emission changed from red to blue under acidic conditions (pH 7-2). The whole process was completely reversible and effective within the pH range 2 to 14. Moreover, this probe system exhibited distinct luminescence quenching upon the addition of Cu 2+ or Fe 3 + . This general modular route will permit easy detection and the concept can be extended to a variety of quinolones for sensing purposes. Copyright © 2016 John Wiley & Sons, Ltd.

Ternary oxide nanostructures and methods of making same

DOEpatents

Wong, Stanislaus S [Stony Brook, NY; Park, Tae-Jin [Port Jefferson, NY

2009-09-08

A single crystalline ternary nanostructure having the formula A.sub.xB.sub.yO.sub.z, wherein x ranges from 0.25 to 24, and y ranges from 1.5 to 40, and wherein A and B are independently selected from the group consisting of Ag, Al, As, Au, B, Ba, Br, Ca, Cd, Ce, Cl, Cm, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Ga, Gd, Ge, Hf, Ho, I, In, Ir, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Rb, Re, Rh, Ru, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Tc, Te, Ti, Tl, Tm, U, V, W, Y, Yb, and Zn, wherein the nanostructure is at least 95% free of defects and/or dislocations.

Structural and magnetic properties of Nd0.67Ba0.33MnO3 manganites with partial replacement of Fe and Cu at Mn-site

NASA Astrophysics Data System (ADS)

Sudakshina, B.; Arun, B.; Chandrasekhar, K. Devi; Yang, H. D.; Vasundhara, M.

2018-06-01

We have investigated the structural and magnetic properties of Nd0.67Ba0.33MnO3 manganite and partial replacement of Mn with Fe and Cu compounds followed by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) and vibrating sample magnetometer (VSM). The Rietveld refinement of XRD indicates orthorhombic crystal structure with I-mma space group for all the compounds and thus obtained lattice parameters confirm the presence of co-operative Jahn-Teller effect. XRD and XAS spectra results suggests the existence of Fe3+ in Fe-substituted compound where as a mixed state of Cu2+ and Cu3+ ions in the Cu-substituted compound. The ferromagnetic (FM) to paramagnetic (PM) transition and magnetic moment is found to decrease upon the substitution of Fe and Cu atoms because of the suppression of double exchange interaction. The theoretically obtained and experimentally determined values of effective PM moment and saturation magnetic moment confirms the presence of inhomogeneous magnetic states containing FM and antiferromagnetic clusters in all the studied compounds.

MBE growth and FMR, BLS and MOKE studies of exchange coupling in Fe whisker/Cr/Fe(001) and in Fe/Cu/Fe(001) 'loose spin' structures

NASA Astrophysics Data System (ADS)

Heinrich, B.; From, M.; Cochran, J. F.; Kowalewski, M.; Atlan, D.; Celinski, Z.; Myrtle, K.

1995-02-01

The exchange coupling has been studied in structures which consist of two ferromagnetic layers separated by non-ferromagnetic spacers (trilayers). The exchange coupling was measured using FMR and BLS techniques in the temperature range 77-400 K. Two systems were investigated: (a) Fe whisker/Cr/Fe(001) and (b) Fe/Cr/Fe(001). The oscillatory thickness dependence of the exchange coupling through a spin-density wave Cr spacer will be discussed and compared with recent data obtained by other groups. Cu interlayers were deposited either in a pure form, or a single monolayer of {Cu}/{Fe} alloy ('loose spins') was inserted between two pure bcc Cu(001) layers. Several such 'loose spin' structures were engineered to test the behavior of 'loose spin' structures. It was found that the presence of Fe impurity atoms has a strong tendency to decrease the direct bilinear exchange coupling. The contribution of 'loose spins' to the exchange coupling can be made significant, and even dominant, by a suitable choice of the RKKY coupling energy between the 'loose spins' and the surrounding ferromagnetic layers.

Separation of copper, iron, and zinc from complex aqueous solutions for isotopic measurement

USGS Publications Warehouse

Borrok, D.M.; Wanty, R.B.; Ridley, W.I.; Wolf, R.; Lamothe, P.J.; Adams, M.

2007-01-01

The measurement of Cu, Fe, and Zn isotopes in natural samples may provide valuable information about biogeochemical processes in the environment. However, the widespread application of stable Cu, Fe, and Zn isotope chemistry to natural water systems remains limited by our ability to efficiently separate these trace elements from the greater concentrations of matrix elements. In this study, we present a new method for the isolation of Cu, Fe, and Zn from complex aqueous solutions using a single anion-exchange column with hydrochloric acid media. Using this method we are able to quantitatively separate Cu, Fe, and Zn from each other and from matrix elements in a single column elution. Elution of the elements of interest, as well as all other elements, through the anion-exchange column is a function of the speciation of each element in the various concentrations of HCl. We highlight the column chemistry by comparing our observations with published studies that have investigated the speciation of Cu, Fe, and Zn in chloride solutions. The functionality of the column procedure was tested by measuring Cu, Fe, and Zn isotopes in a variety of stream water samples impacted by acid mine drainage. The accuracy and precision of Zn isotopic measurements was tested by doping Zn-free stream water with the Zn isotopic standard. The reproducibility of the entire column separation process and the overall precision of the isotopic measurements were also evaluated. The isotopic results demonstrate that the Cu, Fe, and Zn column separates from the tested stream waters are of sufficient purity to be analyzed directly using a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS), and that the measurements are fully-reproducible, accurate, and precise. Although limited in scope, these isotopic measurements reveal significant variations in ??65Cu (- 1.41 to + 0.30???), ??56Fe (- 0.56 to + 0.34???), and ??66Zn (0.31 to 0.49???) among samples collected from different abandoned mines within a single watershed. Hence, Cu, Fe, and Zn isotopic measurements may be a powerful tool for fingerprinting specific metal sources and/or examining biogeochemical reactions within fresh water systems.

Hydroxyl Radical Formation in Solutions of Fe(III) and Hydrogen Peroxide - Impact of Freezing and Thawing Process

NASA Astrophysics Data System (ADS)

Arakaki, T.; Kinjo, M.; Shiroma, K.; Shibata, M.; Miyake, T.; Hirakawa, T.; Sakugawa, H.

2003-12-01

Hydroxyl radical formation was studied by detecting concentration of formate in solutions of hydrated formaldehyde, HOOH, and Fe(III) or Cu(II). Oxidation of hydrated formaldehyde by OH radical is known to form formate. Formate formation increased by about 4 times when the solution underwent freezing and thawing. Although the reaction mechanisms are not clearly understood, we believe that the concentration effect of freezing enhanced the catalytic reactions between HOOH and Fe(III) or Cu(II) and the reduction of transition metals, i.e., Fe(III) to Fe(II) and Cu(II) to Cu(I). The concentration effect also enhanced reactions between Fe(II) and HOOH or Cu(I) and HOOH, which generated OH radical (freeze-Fenton reaction). Study of the effects of pH showed that formate formation was the highest at pH = 4.0, indicating that the speciation of Fe(III) affected the formation of formate. Concentration-dependent experiments demonstrated that Fe is probably the limiting agent under typical atmospheric conditions. Our results suggested that the freezing process could be an important source of hydroxyl radical in high cloud, winter fog, rime ice and freezing acidic rain, and more importantly, a potentially additional oxidation mechanism in the atmosphere.

Brazing characteristics of a Zr-Ti-Cu-Fe eutectic alloy filler metal for Zircaloy-4

NASA Astrophysics Data System (ADS)

Lee, Jung G.; Lim, C. H.; Kim, K. H.; Park, S. S.; Lee, M. K.; Rhee, C. K.

2013-10-01

A Zr-Ti-Cu-Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832 °C to 853 °C was designed by a partial substitution of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown α-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920 °C for 10 min.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhoomeeswaran, H.; Sabareesan, P., E-mail: sendtosabari@gmail.com

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 throughmore » 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).« less

Frustration relieved ferrimagnetism in novel A- and B-site-ordered quadruple perovskite.

PubMed

Chen, Wei-tin; Mizumaki, Masaichiro; Saito, Takashi; Shimakawa, Yuichi

2013-07-28

A novel A- and B-site-ordered quadruple perovskite CaCu3Fe2Sb2O12 was obtained and it shows ferrimagnetism below about 170 K. The B-site Fe spin sublattice adapts a tetrahedral framework in a cubic structure and the Fe(3+)-Fe(3+) antiferromagnetic interaction can result in a geometrical spin frustration as seen in a simple perovskite Ca2FeSbO6. With the introduction of Cu(2+) into the A' site, the antiferromagnetic spin frustration is relieved by the strong Cu(2+)-Fe(3+) interaction, and a ferrimagnetic ordering appears at a much higher temperature than the spin-glass transition temperature.

Structural and magnetic diversity in cyano-bridged bi- and trimetallic complexes assembled from cyanometalates and [M(rac-CTH)]n+ building blocks (CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane).

PubMed

Rodríguez-Diéguez, Antonio; Kivekäs, Raikko; Sillanpää, Reijo; Cano, Joan; Lloret, Francesc; McKee, Vickie; Stoeckli-Evans, Helen; Colacio, Enrique

2006-12-25

Seven new cyano-bridged heterometallic systems have been prepared by assembling [M'(rac-CTH)]n+ complexes (M' = CrIII, NiII, CuII), which have two cis available coordination positions, and [M(CN)6]3- (M = FeIII, CrIII) and [Fe(CN)2(bpy)2]+ cyanometalate building blocks. The assembled systems, which have been characterized by X-ray crystallography and magnetic investigations, are the molecular squares (meso-CTH-H2)[{Ni(rac-CTH)}2{Fe(CN)6)}2].5H2O (2) and [{Ni(rac-CTH)}2{Fe(CN)2(bpy)2}2](ClO4)4.H2O (5), the bimetallic chain [{Ni(rac-CTH)}2{Cr(CN)6)}2Ni(meso-CTH)].4H2O (3), the trimetallic chain [{Ni(rac-CTH)}2{Fe(CN)6)}2Cu(cyclam)]6H2O (4), the pentanuclear complexes [{Cu(rac-CTH}3{Fe(CN)6}2].2H2O (6) and [{Cu(rac-CTH)}3{Cr(CN)6)}2].2H2O (7), and the dinuclear complex [Cr(rac-CTH)(H2O)Fe(CN)6].2H2O (8). With the exception of 5, all compounds exhibit ferromagnetic interaction between the metal ions (JFeNi = 12.8(2) cm-1 for 2; J1FeCu= 13.8(2) cm-1 and J2FeCu= 3.9(4) cm-1 for 6; J1CrCu= 6.95(3) cm-1 and J2CrCu= 1.9(2)cm-1 for 7; JCrFe = 28.87(3) cm-1 for 8). Compound 5 exhibits the end of a transition from the high-spin to the low-spin state of the octahedral FeII ions. The bimetallic chain 3 behaves as a metamagnet with a critical field Hc = 300 G, which is associated with the occurrence of week antiferromagnetic interactions between the chains. Although the trimetallic chain 4 shows some degree of spin correlation along the chain, magnetic ordering does not occur. The sign and magnitude of the magnetic exchange interaction between CrIII and FeIII in compound 8 have been justified by DFT type calculations.

Research and analysis on electrochemical performances of α-Fe{sub 2}O{sub 3} electrode in Li-ion battery with different current collectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lihong, E-mail: huang.lihong@foxmail.com; Min, Zhonghua; Zhang, Qinyong

2015-06-15

Highlights: • We achieved a reversible capacity of 415 mAh g{sup −1} after 30 cycles for α-Fe{sub 2}O{sub 3} electrode in Li-ion battery. • Better electrical performance was obtained when using Cu foam as current collector. • As current collector for α-Fe{sub 2}O{sub 3} electrode, Cu foam is better than Cu foil and Ni foam. • It could avoid the active materials falling off from the current collector during cycling. • It is owe to smaller surface film resistance, charge-transfer resistance, etc. - Abstract: In this work, we reported a simple synthesis of submicron α-Fe{sub 2}O{sub 3} with rod-like structure.more » When it evaluated as electrode material for lithium ion battery, comparing with Cu foil and Ni foam, the as-prepared α-Fe{sub 2}O{sub 3} electrodes with Cu foam current collector exhibited higher reversible capacity of 415 mAh g{sup −1} and more stable cycle performance after 30 cycles. Comparative researches on electrochemical performances of the α-Fe{sub 2}O{sub 3} employing different current collectors (Cu foil, Cu foam and Ni foam) were discussed here in detail. According to our results, the improved electrochemical behaviors of α-Fe{sub 2}O{sub 3} electrode with Cu foam current collector could be attributed to its particular electrode structure, i.e., porous, good electric conductivity, closed adhere to the electrode materials. Just because of that, it may make sure an easy accessibility of electrolytes and fast transportation of lithium ions, importantly, it could avoid the active materials falling off from the current collector on account of volume expansion.« less

Effect of nickel addition on mechanical properties of powder forged Fe-Cu-C

NASA Astrophysics Data System (ADS)

Archana Barla, Nikki

2018-03-01

Fe-Cu-C system is very popular in P/M industry for its good compressibility and dimensional stability with high strength. Fe-Cu-C is a structural material and is used where high strength with high hardness is required. The composition of powder metallurgy steel plays a vital role in the microstructure and physical properties of the sintered component. Fe-2Cu-0.7C-Ni alloy with varying nickel composition (0%, 0.5%, 1.0%, 1.5%, 2.0%, and 3.0%) wt. % was prepared by powder metallurgy (P/M) sinter forging process. The present work discuss the effect of varying nickel content on microstructure and mechanical properties.

Production and Isomeric Distribution of Xanthylium Cation Pigments and Their Precursors in Wine-like Conditions: Impact of Cu(II), Fe(II), Fe(III), Mn(II), Zn(II), and Al(III).

PubMed

Guo, Anque; Kontoudakis, Nikolaos; Scollary, Geoffrey R; Clark, Andrew C

2017-03-22

This study establishes the influence of Cu(II), Fe(II), Fe(III), Zn(II), Al(III), and Mn(II) on the oxidative production of xanthylium cations from (+)-catechin and either tartaric acid or glyoxylic acid in model wine systems. The reaction was studied at 25 °C using UHPLC and LC-HRMS for the analysis of phenolic products and their isomeric distribution. In addition to the expected products, a colorless product, tentatively assigned as a lactone, was detected for the first time. The results show the importance of Fe ions and a synergistic influence of Mn(II) in degrading tartaric acid to glyoxylic acid, whereas the other metal ions had minimal activity in this mechanistic step. Fe(II) and Fe(III) were shown to mediate the (+)-catechin-glyoxylic acid addition reaction, a role previously attributed to only Cu(II). Importantly, the study demonstrates that C-8 addition products of (+)-catechin are promoted by Cu(II), whereas C-6 addition products are promoted by Fe ions.

The synthesis of Cu/Fe/Fe3O4 catalyst through the aqueous solution ball milling method assisted by high-frequency electromagnetic field

NASA Astrophysics Data System (ADS)

Yingzhe, Zhang; Yuxing, He; Qingdong, Qin; Fuchun, Wang; Wankun, Wang; Yongmei, Luo

2018-06-01

In this paper, nano-magnetic Cu/Fe/Fe3O4 catalyst was prepared by a new aqueous solution ball milling method assisted by high-frequency electromagnetic field at room temperature. The products were characterized by means of X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), and vibrating sample magnetometer (VSM). Microwave induced catalytic degradation of methylene blue (MB) was carried out in the presence of Cu/Fe/Fe3O4. The concentration of methylene blue was determined by UV-Vis spectrophotometry. The solid catalyst showed high catalytic activity of degrade MB and considerable saturation magnetization, lower remanence and coercivity. It indicate that the catalyst can be effectively separated for reuse by simply applying an external magnetic field and it can greatly promote their potential industrial application to eliminate organic pollutants from waste-water. Finally, we found that it is the non-thermal effect of microwave that activated the catalytic activity of Cu/Fe/Fe3O4 to degrade MB.

Type 2 pyoverdine from Pseudomonas aeruginosa strain BUP2 as turn-off biosensor for the rapid detection of iron and copper ions in contaminated water.

PubMed

Unni, Kizhakkepowathial Nair; Priji, Prakasan; Sajith, Sreedharan; Faisal, Panichikkal Abdul; Shainy, Karippayi Mattil; Joseph, Abraham; Babu, Moolath Girish; Benjamin, Sailas

2016-09-23

Employing fluorescent quenching mechanism, type 2 pyoverdine (PVD) purified from Pseudomonas aeruginosa strain BUP2 (new strain isolated from the rumen of Malabari goat) was used as a simple, convenient and inexpensive tool for the rapid detection of Fe and Cu ions in contaminated drinking water samples. The fluorescence emitted at λ 460 by PVD (in sterile water), mounted on a glass slide was efficiently quenched by the ions of heavy metals like Fe and Cu. The fluorescence quenching effect of PVD was monitored using UV trans-illuminator, and subsequently quantified and confirmed by spectrofluorimetry. Upon exposure for about 50 sec at 25 °C, this quenching efficiency could directly be assessed by naked eye with the aid of a UV trans-illuminator. The linear range of detection for Fe was 1 to 60 µM, while that of Cu was 1 to 20 µM. The limits of detection at µM concentration for Fe 3+ , Fe 2+ and Cu 2+ were 0.23, 0.24 and 0.38, respectively. The quenching of fluorescence was more pronounced in Fe-PVD system than Cu-PVD, and this observation was in corroboration with the Pearson acid base concept; being a hard acid, Fe 3+ effectively bound with the O-ligands and this ability was less in Cu 2+ , a border line acid. Briefly, this study proposed the use of type 2 PVD as a turn-off biosensor for the rapid screening of heavy metals like Fe and Cu in drinking water, at ppm levels only with the aid of UV trans-illuminator at 25 °C in 50 sec.

Effect of sputtering condition and heat treatment in Co/Cu/Co/FeMn spin valve

NASA Astrophysics Data System (ADS)

Kim, Hong Jin; Bae, Jun Soo; Lee, Taek Dong; Lee, Hyuck Mo

2002-03-01

The exchange field of Cu(50 Å)/FeMn(50 Å)/Co(50 Å) sputtered on Si substrate was studied in terms of surface roughness and phase formation of γ-FeMn under a variety of Ar pressures and powers in sputtering. It was found that the exchange field is stronger when the surface is smoother and the FeMn layer forms better. The exchange bias field increased by more than three times after heat treatment. The effect of heat treament on magnetoresistance (MR) and resistance of the top spin valve, substrate/Co(30 Å)/Cu(30 Å)/Co(30 Å)/FeMn(150 Å), was studied. It was observed that the MR started to increase with annealing temperature and the effect was significant at 150°C. The heat treatment led to the disappearance of the intermixed layer between Co and Cu, and the concentration profile of Cu became flat and smooth at this temperature.

High-temperature friction and wear studies of Fe-Cu-Sn alloy with graphite as solid lubricant under dry sliding conditions

NASA Astrophysics Data System (ADS)

Mushtaq, Shuhaib; Wani, M. F.

2018-02-01

Solid lubricants are particularly used in the advanced mechanical motion systems with extreme conditions such as (high temperature, vacuum, radiation, extreme contact pressure, etc). The main focus of this paper is to study the dry sliding friction and wear behavior of Fe-Cu-Sn alloy with varying wt% of graphite at high temperature up to 423 K. The influence of temperature, sliding distance and load on friction and wear behavior of Fe-Cu-Sn alloy against EN8 steel was studied using ball (EN8) on disc (Fe-Cu-Sn alloy). Lower wear and lower friction of Fe-Cu-Sn alloy were observed at high temperature, as compared to room temperature. Surface morphological and surface analytical studies of fresh and worn surfaces were carried out using optical microscopy, 3D profilometer, scanning electron microscope, energy dispersive x-ray spectroscopy, XRD, and Raman spectroscopy to understand the friction and wear behavior.

Cu1–xFexO: hopping transport and ferromagnetism

PubMed Central

Nasir, Mohd.; Islam, Rakibul; Ahmed, Md. A; Ayaz, Saniya; Kumar, Gautham; Kumar, Sunil; Prajapat, C. L.; Roussel, Frederick; Biring, Sajal

2017-01-01

Single phase, sol–gel prepared Cu1–xFexO (0 ≤ x ≤ 0.125) powders are characterized in terms of structural, electronic and magnetic properties. Using dielectric and magnetic studies we investigate the coupling of electron and spin. The electrical conductivities and activation energies are studied with increasing Fe content. Modelling of experimental conductivity data emphasizes a single hopping mechanism for all samples except x = 0.125, which have two activation energies. Hole doping is confirmed by confirming a majority Fe3+ substitution of Cu2+ in CuO from X-ray photoelectron spectroscopy studies (XPS). Such a substitution results in stabilized ferromagnetism. Fe substitution introduces variation in coercivity as an intrinsic magnetic property in Fe-doped CuO, and not as a secondary impurity phase. PMID:28989741

Content and Bioaccumulation of Nine Mineral Elements in Ten Mushroom Species of the Genus Boletus

PubMed Central

Wang, Xue-Mei; Zhang, Ji; Li, Tao; Wang, Yuan-Zhong; Liu, Hong-Gao

2015-01-01

Concentrations and bioconcentration potential of nine elements (Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn) in ten species of wild edible Boletus and the corresponding underlying soils were analyzed. The analyses were performed using inductively coupled plasma atomic emission spectrophotometer. Boletus showed relative abundant contents of P, K, Fe, Mg, Ca, and Na and less of Zn, Cu, and Mn. Caps compared to stalks were enriched in P, K, Cu, Mg, and Zn, while stalks were enriched in Mn. The elements such as P and K were accumulated (BCF > 1), while Ca, Fe, Mg, Mn, and Na were excluded (BCF < 1) in the fruiting bodies. The correlation analysis indicated high correlations between Cu, Mn, Ca, and Fe in the mushrooms as compared to the corresponding soils. Significant correlations were also obtained between Cu-P (r = 0.775), Fe-P (r = 0.728), and Zn-P (r = 0.76) for caps and Cu-Mg (r = 0.721), Fe-Mg (r = 0.719), Zn-Mg (r = 0.824), and Zn-P (r = 0.818) for stalks. The results of this study imply that ability of fungi to accumulate elements from substrate could be influenced by mushroom species and underlying soil substrates. PMID:26146585

Content and Bioaccumulation of Nine Mineral Elements in Ten Mushroom Species of the Genus Boletus.

PubMed

Wang, Xue-Mei; Zhang, Ji; Li, Tao; Wang, Yuan-Zhong; Liu, Hong-Gao

2015-01-01

Concentrations and bioconcentration potential of nine elements (Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn) in ten species of wild edible Boletus and the corresponding underlying soils were analyzed. The analyses were performed using inductively coupled plasma atomic emission spectrophotometer. Boletus showed relative abundant contents of P, K, Fe, Mg, Ca, and Na and less of Zn, Cu, and Mn. Caps compared to stalks were enriched in P, K, Cu, Mg, and Zn, while stalks were enriched in Mn. The elements such as P and K were accumulated (BCF > 1), while Ca, Fe, Mg, Mn, and Na were excluded (BCF < 1) in the fruiting bodies. The correlation analysis indicated high correlations between Cu, Mn, Ca, and Fe in the mushrooms as compared to the corresponding soils. Significant correlations were also obtained between Cu-P (r = 0.775), Fe-P (r = 0.728), and Zn-P (r = 0.76) for caps and Cu-Mg (r = 0.721), Fe-Mg (r = 0.719), Zn-Mg (r = 0.824), and Zn-P (r = 0.818) for stalks. The results of this study imply that ability of fungi to accumulate elements from substrate could be influenced by mushroom species and underlying soil substrates.

Spectro-photometric determinations of Mn, Fe and Cu in aluminum master alloys

NASA Astrophysics Data System (ADS)

Rehan; Naveed, A.; Shan, A.; Afzal, M.; Saleem, J.; Noshad, M. A.

2016-08-01

Highly reliable, fast and cost effective Spectro-photometric methods have been developed for the determination of Mn, Fe & Cu in aluminum master alloys, based on the development of calibration curves being prepared via laboratory standards. The calibration curves are designed so as to induce maximum sensitivity and minimum instrumental error (Mn 1mg/100ml-2mg/100ml, Fe 0.01mg/100ml-0.2mg/100ml and Cu 2mg/100ml-10mg/ 100ml). The developed Spectro-photometric methods produce accurate results while analyzing Mn, Fe and Cu in certified reference materials. Particularly, these methods are suitable for all types of Al-Mn, Al-Fe and Al-Cu master alloys (5%, 10%, 50% etc. master alloys).Moreover, the sampling practices suggested herein include a reasonable amount of analytical sample, which truly represent the whole lot of a particular master alloy. Successive dilution technique was utilized to meet the calibration curve range. Furthermore, the workout methods were also found suitable for the analysis of said elements in ordinary aluminum alloys. However, it was observed that Cush owed a considerable interference with Fe, the later one may not be accurately measured in the presence of Cu greater than 0.01 %.

Preparation and study of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) composite multiferroics

NASA Astrophysics Data System (ADS)

Murtaza, Tahir; Ali, Javid; Khan, M. S.

2018-07-01

The parent and mixed spinel-perovskite composite of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) has been prepared by solid-state reaction method and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, magnetometry and P-E lope tracer. The XRD results showed the formation of single phase tetragonal spinel CuFe2O4 and tetragonal perovskite BaTiO3 at room temperature, further XRD of composite 0.1CuFe2O4-0.9BaTiO3 reflects the two crystallographic phases with 1:9 ratio. The SEM micrographs show the homogeneous and uniform formation of the samples. Through EDAX analysis, the chemical composition of the sample is found to be same as the nominal composition. The high field Mossbauer data of CuFe2O4 sample shows the ferrimagnetic ordering in the sample. The observed M-H and P-E loops of the composite 0.1CuFe2O4-0.9BaTiO3 sample show the presence of spontaneous magnetization and spontaneous electric polarization indicating the multiferroic nature of the sample.

The combination of activated natural zeolite-bentonite to reduce Fe and Cu in refined bleached palm oil (RBPO) by using atomic absorption spectrophotometer method

NASA Astrophysics Data System (ADS)

Zakwan; Raja, PM; Giyanto

2018-02-01

Indonesia is one of the crude palm oil (CPO) production country in the world. As many products are derivated from the CPO, the quality must be increased continuously. One of the things that influence the quality of palm oil is the Fe and Cu content. The objective of this research was to reduce Fe and Cu content in Refined Bleached Palm Oil (RBPO). In processing CPO or Refined Bleachead Palm Oil (RBPO) may be contaminated by Fe and Cu from metal tank and pipe in the factory. The zeolite and bentonite was activated by maceration method using hydrochloric acid (0,1 N). Four batch reactions consisting of refined palm oil (RPO), activated natural zeolite-bentonite (ANZB) was bleached by heating and stirring them at about 105°C and 1200 rpm for 30 minutes. The results showed that all combinations of ANZB can reduce the Fe content. Thereafter, the optimal combination of ANZB was obtained in K1, K2 and K4 with Cu content 0.02 ppm. In the future, it is needed to study on the reduction of the Fe and Cu content in palm oil with the other adsorbent.

Magnetic susceptibility of YBa2(Cu/1-x/Fe/x/)3O(y) prepared by various heat treatments

NASA Astrophysics Data System (ADS)

Shibata, Tomohiko; Katsuyama, Shigeru; Yoshimura, Kazuyoshi; Kosuge, Koji

1991-02-01

The magnetic susceptibility of YBa2(Cu/1-x/Fe/x/)3O(y) specimens was measured following a standard heat treatment and a special heat treament stabilizing the orthorhombic phase to higher Fe concentrations. The values of the effective magnetic moment per Fe in the Cu1 site, estimated from the magnetic susceptibility and Mossbauer effect measurements, were 4.4 and 2.2 muB for the standard and specially treated specimens, respectively. The smaller effective magnetic moment in the case of specially treated specimens is attributed to the antiferromagnetic coupling between Fe spins at high temperatures.

Cu@Fe3O4 core-shell nanoparticle-catalyzed oxidative degradation of the antibiotic oxytetracycline in pre-treated landfill leachate.

PubMed

Pham, Van Luan; Kim, Do-Gun; Ko, Seok-Oh

2018-01-01

Novel Cu@Fe 3 O 4 core-shell nanoparticles prepared via a simple reduction method were evaluated for degradation of oxytetracycline (OTC) in pre-treated leachate (L p-TREA ) (leachate treated by conventional methods). Changes in the characteristics of dissolved organic matter (DOM) in the leachate were also investigated to gain a better understanding of the effects of DOM on the performance of Cu@Fe 3 O 4 . An excellent OTC degradation of >99% was achieved within 30 min under conditions of 1 g/L Cu@Fe 3 O 4 , 20 mg/L OTC, 20 mM H 2 O 2 , and initial pH 3.0, which was similar to the efficiency obtained in deionized water (90% even at pH 9.05). Humic acid (HA) and fulvic acid (FA) were completely degraded at initial pH 3, while aromatic protein (AP) with 32.7% of 1-3 kDa constituents were totally transformed to 0.5-1 kDa compounds, and 17% < 0.5 kDa material was degraded. The OTC removal rate decreased gradually as Cu@Fe 3 O 4 was repeatedly used, but it was significantly enhanced when Cu@Fe 3 O 4 was washed after five uses to remove the organic matter on its surface. The results suggest that Cu@Fe 3 O 4 is a promising and effective catalyst for pharmaceutical and personal care product degradation in landfill leachates. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous magnetic investigations of Cu precipitation and recovery in thermally aged Fe-Cu alloy by first-order-reversal-curves

NASA Astrophysics Data System (ADS)

Kobayashi, Satoru; Kawagoe, Riko; Murakami, Hiroaki

2018-05-01

We have measured first-order reversal curves (FORCs) for Fe-1wt%Cu alloy thermally aged at 753 K up to 20000 min. While hardness exhibits a maximum at around 1000 min, reflecting the formation and growth of Cu precipitates, major-loop coercivity monotonically decreases and becomes almost constant above 100 min.; an increase of coercivity associated with Cu precipitation is masked by a large decrease due to recovery. On the other hand, FORC diagrams exhibit two distribution peaks at low and high switching fields after aging. While the former shifts towards a lower switching field after aging, reflecting recovery, the latter shows up after aging up to ˜1000 min, possibly due to the formation of Cu precipitates. These observations demonstrate that FORCs are useful to separately evaluate competing microstructural changes in thermally aged Fe-Cu alloy where recovery and Cu precipitation take place simultaneously.

Redox equilibria of multivalent ions in silicate glasses

NASA Technical Reports Server (NTRS)

Lauer, H. V., Jr.; Morris, R. V.

1977-01-01

Experimental studies were made on the compositional dependence of the redox equilibrium of Eu in synthetic silicate liquids, together with an empirical model describing the observed compositional dependence. Electron paramagnetic resonance (EPR) was used to measure the concentration ratio of Eu(2+) to Eu(3+) in various glasses formed by rapidly quenching silicate liquids. The compositional field studied comprised mixtures of SiO2, TiO2, Al2O3, CaO, MgO, and Na2O. The proposed model describes the Eu(2+)/Eu(3+) ratio over the entire compositional field in terms of parameters easily related to each glass composition. The general applicability and utility of the model is further demonstrated by its application to the Fe(2+)-Fe(3+), Ce(3+)-Ce(4+), and Cr(3+)-Cr(6+) redox reactions in binary alkali oxide silicate glasses of Li, Na, and K.

Structural Inheritance and Redox Performance of Nanoporous Electrodes from Nanocrystalline Fe85.2B10-14P0-4Cu0.8 Alloys

PubMed Central

Fu, Chaoqun; Xu, Lijun; Dan, Zhenhua; Makino, Akihiro; Hara, Nobuyoshi; Qin, Fengxiang; Chang, Hui

2017-01-01

Nanoporous electrodes have been fabricated by selectively dissolving the less noble α-Fe crystalline phase from nanocrystalline Fe85.2B14–xPxCu0.8 alloys (x= 0, 2, 4 at.%). The preferential dissolution is triggered by the weaker electrochemical stability of α-Fe nanocrystals than amorphous phase. The final nanoporous structure is mainly composed of amorphous residual phase and minor undissolved α-Fe crystals and can be predicted from initial microstructure of nanocrystalline precursor alloys. The structural inheritance is proved by the similarity of the size and outlines between nanopores formed after dealloying in 0.1 M H2SO4 and α-Fe nanocrystals precipitated after annealing of amorphous Fe85.2B14−xPxCu0.8 (x = 0, 2, 4 at.%) alloys. The Redox peak current density of the nanoporous electrodes obtained from nanocrystalline Fe85.2B10P4Cu0.8 alloys is more than one order higher than those of Fe plate electrode and its counterpart nanocrystalline alloys due to the large surface area and nearly-amorphous nature of ligaments. PMID:28594378

Low temperature texture development in Nd2Fe14B/α-Fe nanocomposite magnets via equal channel angular pressing

NASA Astrophysics Data System (ADS)

Besley, L.; Garitaonandia, J. S.; Molotnikov, A.; Kishimoto, H.; Kato, A.; Davies, C.; Suzuki, K.

2018-05-01

While suitable texture has been developed in Nd2Fe14B/α-Fe nanocomposites via thermomechanical processing methods such as die upsetting by incorporating low melting point eutectic Nd-Cu additives, significant grain coarsening occurs during this process due to the high temperature and long timescales involved, resulting in a loss of exchange coupling. Equal channel angular pressing (ECAP) is a severe plastic deformation technique which has been successfully used to produce a suitable texture in single-phase Nd2Fe14B at temperatures on the order of 500°C while preserving grain sizes on the order of 20-30nm. We investigate the development of texture in a commercial Nd2Fe14B/α-Fe nanocomposite alloy with added Nd90Cu10 produced via ECAP and then characterise it using texture x-ray diffraction and magnetic measurements. It is found that initial texture can be developed in this nanocomposite system at T = 520°C via ECAP. The average grain size of Nd2Fe14B as measured via X-ray diffraction after ECAP remains below 50nm with a developed texture. The effect of varying the amount of Nd90Cu10 additive is also investigated. It is found that with decreasing Nd90Cu10, the degree of texture is reduced while the volume fraction of α-Fe increases. This work demonstrates the development of texture in nanocomposite Nd2Fe14B/α-Fe with Nd-Cu additives whilst maintaining a grain size of approximately 50nm.

Effects of aging time and temperature of Fe-1wt.%Cu on magnetic Barkhausen noise and FORC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saleh, Muad; Cao, Yue; Edwards, Danny J.

Magnetic Barkhausen noise (MBN), hysteresis measurements, first order reversal curves (FORC), Vickers microhardness, and Transmission Electron Microscopy (TEM) analyses were performed on Fe-1wt.%Cu (Fe-Cu) samples isothermally aged at 700°C for 0.5 – 25 hours to obtain samples with different sized Cu precipitates and dislocation structures. Fe-Cu is used to simulate the thermal and irradiation-induced defects in copper-containing nuclear reactor materials such as cooling system pipes and pressure vessel materials. The sample series showed an initial increase followed by a decrease in hardness and coercivity with aging time, which is explained by Cu precipitates formation and growth as observed by TEMmore » measurements. Further, the MBN envelope showed a continuous decrease in its magnitude and the appearance of a second peak with aging. Also, FORC diagrams showed multiple peaks whose intensity and location changed for different aging time. The changes in FORC diagrams are attributed to combined changes of the magnetic behavior due to Cu precipitate characteristics and dislocation structure. A second series of samples aged at 850°C, which is above the solid solution temperature of Fe-Cu, was studied to isolate the effects of dislocations. These samples showed a continuous decrease in MBN amplitude with aging time although the coercivity and hardness did not change significantly. The decrease of MBN amplitude and the appearance of the second MBN envelope peak are attributed to the changes in dislocation density and structure. This study shows that the effect of dislocations on MBN and FORC of Fe-Cu materials can vary significantly and should be considered in interpreting magnetic signatures.« less

Flux pinning forces in irradiated a-axis oriented EuBa{sub 2}Cu{sub 3}O{sub 7} films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, J. I.; Gonzalez, E. M.; Kwok, W.-K

1999-10-12

{alpha}-axis oriented EuBa{sub 2}Cu{sub 3}O{sub 7} films have been irradiated with high energy heavy ions in different configurations to study the possible pinning role of the artificial defects in this kind of samples. The original pinning limiting mechanism of the samples is not essentially altered what the irradiation is parallel to the CuO{sub 2} planes. However, when it is deviated from this direction, an increase in critical current density and a change in pinning force are observed when the magnetic field is parallel to the columnar defects at values around the matching field.

Effect of Cu2+ substitution on the structural, magnetic and electrical properties of gadolinium orthoferrite

NASA Astrophysics Data System (ADS)

Sai Vandana, C.; Hemalatha Rudramadevi, B.

2018-04-01

The pure and copper (Cu) substituted Gadolinium orthoferrites, GdFeO3, GdCu0.1Fe0.9O3, GdCu0.2Fe0.8O3 and GdCu0.3Fe0.7O3 were synthesized by conventional solid state method. The structural, morphological, dielectric, magnetic and impedance properties of Cu substituted Gadolinium orthoferrites have been investigated. The crystallographic phase as well as the substitution of Cu2+ ions in the lattice of GdFeO3 is confirmed from the x-ray diffraction patterns. The Fourier transform infrared spectra exhibit two prominent fundamental absorption peaks at ∼417 cm‑1 and 545 cm‑1. These bands are related to inherent stretching vibrations of metals at octahedral and tetrahedral sites respectively. The coercivity (Hc) and saturation magnetization (Ms) of the synthesized samples at different temperatures were determined from the hysteresis plots. Higher coercive values, 598 Oe and 600 Oe were achieved in GdCu0.1Fe0.9O3 ferrites compared to 527 Oe and 360 Oe in pure GdFeO3 at room temperature (300 K) and low temperature (20 k) respectively. Dielectric dispersion has been observed for gadolinium ferrite samples with Maxwell–Wagner type interfacial polarization. The decrease of dielectric constant and dielectric loss tangent with an increase in frequency was observed. The conduction due to charge hopping between localized states was confirmed from AC conductivity measurements. The composition dependent cationic distributions estimated from XRD, magnetic and electrical studies are in good agreement with each other. The achieved results indicate that the substitution of Cu in gadolinium orthoferrite strongly influences the crystal structure, magnetic and electrical properties thereby making them suitable as multiple state memory devices, transducers, electronic field controlled ferromagnetic resonance devices and spintronic devices.

Synthesis, structural and electronic properties of monodispersed self-organized single crystalline nanobricks of isocubanite CuFe{sub 2}S{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyubutin, Igor S., E-mail: lyubutinig@mail.ru; Lin, Chun-Rong, E-mail: crlin@mail.nptu.edu.tw; Starchikov, Sergey S.

2015-01-15

The nanoparticles with a pure cubic phase of isocubanite CuFe{sub 2}S{sub 3} are successfully synthesized for the first time. The particles are self-organized into the single crystalline nanocomposites with a shape of “bricks” which are well ordered in a certain anisotropic orientation. All bricks have nearly the same shape and dimensions and may be considered as monodispersed nanobricks. Magnetic measurements show paramagnetic behavior of the compound down to 4.2 K with the antiferromagnetic correlation between iron ions. An average magnetic moment is about 2.8–3.0 μ{sub B} per formula unit CuFe{sub 2}S{sub 3}. Mössbauer spectroscopy data reveal that the ferric ionsmore » in isocubanite are in the high-spin state (spin S=5/2) whereas the ferrous ions are in the intermediate-spin state (S=1). The Fe{sup 3+} and Fe{sup 2+} ions are distributed randomly over tetrahedral sites and the electron exchange between these ions is absent. This can explain nonmagnetic behavior of isocubanite. In the suggested method, the combined nanocomposites containing the magnetic chalcopyrite CuFeS{sub 2} and the nonmagnetic isocubanite CuFe{sub 2}S{sub 3} can be synthesized in a certain sequence. Such composites could be useful for the applied nanotechnology. - Graphical abstract: Self-organized single crystalline “nanobricks” of isocubanite CuFe{sub 2}S{sub 3} synthesized by a thermal pyrolysis method. - Highlights: • Self-organized single crystalline “nanobricks” of CuFe{sub 2}S{sub 3} were synthesized. • All bricks are nearly monodispersed and well-ordered in a certain anisotropic orientation. • XRD, HRTEM, magnetic measurements and Mössbauer spectroscopy were used for characterization. • Nanobricks are paramagnetic down to 4.2 K with effective magnetic moment about 3.0 μ{sub B} per f.u. • Mössbauer spectroscopy data indicate different spin states of Fe{sup 2+} and Fe{sup 3+} ions.« less

Ternary metal fluorides as high-energy cathodes with low cycling hysteresis

DOE PAGES

Wang, Feng; Kim, Sung -Wook; Seo, Dong -Hwa; ...

2015-03-26

In this study, transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (3–4 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M 1 yM 2 1-yF x: M 1, M 2 = Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid–solution Cu yFe 1-yF 2, reversible Cu and Fe redox reactionsmore » are achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. In conclusion, although the reversible capacity of Cu conversion fades rapidly, likely due to Cu + dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries.« less

Complex permeability and permittivity spectra of percolated Fe50Co50/Cu granular composites

NASA Astrophysics Data System (ADS)

Massango, Herieta; Tsutaoka, Takanori; Kasagi, Teruhiro; Yamamoto, Shinichiro; Hatakeyama, Kenichi

2017-11-01

Complex permeability and permittivity spectra of Fe50Co50/Cu hybrid granular composite materials have been studied in the RF to microwave frequency range. At low Cu particle content, the Fe50Co50/Cu hybrid sample shows a metallic percolative property with the electrical conductivity value about 0.1 S/cm. However, the low frequency plasmonic (LFP) state with negative permittivity (ENG) spectrum was not observed. An abrupt increase of electrical conductivity takes place at 14 to 16 vol% Cu content where the conductivity becomes above 1.0 S/cm; the Fe50Co50/Cu composite possesses the LFP state with negative permittivity spectrum below a characteristic frequency. The complex permittivity spectra in the LFP state can be described by the Drude model. Magnetic permeability spectrum in the LFP state showed a broad frequency dispersion above 10 MHz; a small negative permeability (MNG) dispersion was observed from 2 to 10 GHz. Consequently, the double negative (DNG) electromagnetic property with MNG and ENG was realized in the microwave range for the Cu content of 26 and 30 vol%.

Ternary metal fluorides as high-energy cathodes with low cycling hysteresis

PubMed Central

Wang, Feng; Kim, Sung-Wook; Seo, Dong-Hwa; Kang, Kisuk; Wang, Liping; Su, Dong; Vajo, John J.; Wang, John; Graetz, Jason

2015-01-01

Transition metal fluorides are an appealing alternative to conventional intercalation compounds for use as cathodes in next-generation lithium batteries due to their extremely high capacity (3–4 times greater than the current state-of-the-art). However, issues related to reversibility, energy efficiency and kinetics prevent their practical application. Here we report on the synthesis, structural and electrochemical properties of ternary metal fluorides (M1yM21-yFx: M1, M2=Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid–solution CuyFe1-yF2, reversible Cu and Fe redox reactions are achieved with surprisingly small hysteresis (<150 mV). This finding indicates that cation substitution may provide a new avenue for tailoring key electrochemical properties of conversion electrodes. Although the reversible capacity of Cu conversion fades rapidly, likely due to Cu+ dissolution, the low hysteresis and high energy suggest that a Cu-based fluoride cathode remains an intriguing candidate for rechargeable lithium batteries. PMID:25808876

Geochemistry of Zr, Hf, and REE in a wide spectrum of Eh and water composition: The case of Dead Sea Fault system (Israel)

NASA Astrophysics Data System (ADS)

Censi, P.; Raso, M.; Yechieli, Y.; Ginat, H.; Saiano, F.; Zuddas, P.; Brusca, L.; D'Alessandro, W.; Inguaggiato, C.

2017-03-01

Along the Jordan Valley-Dead Sea Fault area several natural waters in springs, wells, and catchments occur. The chemical-physical characters of the studied waters allowed for the first time the investigation of the Zr and Hf geochemical behavior, apart from REE, extended to a wide range of Eh, temperature, salinity, and pH conditions. The results of this study indicate that the dissolved Zr and Hf distribution in natural waters is strongly influenced by redox conditions since these in turn drive the deposition of Fe-oxyhydroxides or pyrite. In oxidizing waters saturated or oversaturated in Fe-oxyhydroxides (Group 1), superchondritic Zr/Hf values are measured. On the contrary, in waters where Eh < 0 values occur (Group 2), chondritic Zr/Hf values are found. Superchondritic Zr/Hf values are produced by the preferential Hf scavenging onto Fe-oxyhydroxides that is inhibited under reducing conditions consistent with the water oversaturation relative to pyrite. Redox conditions also influence the amplitude of Ce and Eu anomalies. Oxidized Group-1 waters show negative Ce anomalies related to the oxidative Ce scavenging as CeO2 onto Fe-oxyhydroxide. Reduced Group-2 waters show positive Eu anomaly values consistent with the larger Eu2+ concentration relative to Eu3+ in these waters suggested by model calculations. The higher stability of Eu2+ with respect to its trivalent neighbors along the REE series can explain the above mentioned positive Eu anomaly values. The middle-REE enrichment observed in shale-normalized REE patterns of studied waters can be ascribed to carbonate and/or gypsum dissolution.

Fenton-like Degradation of Phenol Catalyzed by a Series of Fe-Containing Mixed Oxides Systems

NASA Astrophysics Data System (ADS)

Alhmoud, T. T.; Mahmoud, S. S.; Hammoudeh, A. Y.

2018-02-01

In our attempts to develop a solid catalyst to degrade organic pollutants in wastewater via the Fenton-like reaction, six Fe-containing mixed oxide systems were prepared by means of the sol-gel auto-combustion method to have the following stoichiometries: CuFe1.2O2.8, BaFe7.2O11.8, BaFe7.2Cu2O13.8, BaFe5.4V3O16.6, BaFe4.8Cu2V3O17.7 and Ag2Fe5.4V3O16.6. The prepared systems were thermally treated at 550°C, 650°C, 800°C and 1100°C, and then characterized by XRD to identify the present phases. The systems were tested with respect to their catalytic efficiency in the degradation of phenol (200 ppm) in water where CuFe1.2O2.8 was found to be the most reactive one (80% removal in 60 min). It showed thereby first-order kinetics and an enhanced behavior under irradiation with a 30-W LED light source. The positive role of irradiation was most obvious in the case of Ag2Fe5.4V3O16.6 in which almost complete conversion was achieved in 120 min compared to only 45% in the same period but without irradiation. However, increasing the temperature at which thermal treatment is performed was found to suppress the catalytic activity of the system. Due to their high efficiency and rather low leaching rates of constituents, CuFe1.2O2.8 or Ag2Fe5.4V3O16.6 seem to be very promising in the Fenton-like degradation of organic pollutants.

Out-of-Plane Disorder Effects on the Energy Gaps and Electronic Charge Order in Bi2Sr1.7R0.3CuO6+δ (R = La and Eu)

NASA Astrophysics Data System (ADS)

Kurosawa, Tohru; Takeyama, Kohsaku; Baar, Stefan; Shibata, Yuto; Kataoka, Moeko; Mizuta, Shusei; Yoshida, Hiroshi; Momono, Naoki; Oda, Migaku; Ido, Masayuki

2016-04-01

We performed STM/STS experiments at 8 K in Bi2Sr1.7R0.3CuO6+δ (R-Bi2201) systems that had optimal (OP) hole-doping levels (˜0.17) but different Tc values, 35 K for R = La and 20 K for R = Eu, and examined out-of-plane disorder effects on the superconducting (SC) gap (SCG) and the pseudogap (PG) which is associated with the so-called "checkerboard charge order" (CCO). As out-of-plane disorders are strengthened by replacing La with Eu in OP R-Bi2201, the antinodal PG size ΔPG increases from ˜30 to ˜60 meV, the nodal SCG size ΔSC seems to decrease from ˜7 to ˜4 meV, and the pairing gap amplitude Δ0 or d-wave gap size at the antinodes is almost unchanged (Δ0 ˜ 15 meV). These gap sizes for OP doping in Eu-Bi2201 are comparable to those for an underdoping level of ˜0.1 in La-Bi2201. Although out-of-plane disorders strongly affect the electronic system of the Cu-O plane, they have no effect on the period of the CCO, which is five times the lattice constant (5a) along the Cu-O bond directions for OP doping and 4a for p ˜ 0.1. We suggest that the concentration of holes doped into the Cu-O plane may be an essential factor for determining the period of the CCO.

Efficiency of several leaching reagents on removal of Cu, Pb, Cd, and Zn from highly contaminated paddy soil.

PubMed

Gao, Ruili; Zhu, Pengfei; Guo, Guangguang; Hu, Hongqing; Zhu, Jun; Fu, Qingling

2016-11-01

The efficiency of five different single leaching reagents (tartaric acid (TA), citric acid (CA), CaCl 2 , FeCl 3 , EDTA) and two different composite leaching reagents (CA + FeCl 3 , CA + EDTA) on removing Cu, Pb, Zn, and Cd from contaminated paddy soil in Hunan Province (in China) was studied. The results indicated that the efficiencies of CA, FeCl 3 , and EDTA on extracting Cu, Pb, Cd, and Zn from soil were greater than that of TA and CaCl 2 , and their extraction efficiencies were EDTA ≥ FeCl 3 > CA. The efficiencies of CA + FeCl 3 on extracting Cu, Pb, Cd, and Zn were higher than that of single CA or FeCl 3 . The 25 mmol L -1 CA + 20 mmol L -1 FeCl 3 was a promising composite leaching reagent for paddy soil, and it could remove Cu (57.6 %), Pb (59.3 %), Cd (84.8 %), and Zn (28.0 %), respectively. With the same amount of leaching reagent, the efficiency of continuous leaching by several times was higher than that by once. In addition, the easily reducible and oxidizable fractions of heavy metals showed significant decrease during the process of leaching.

Observation of super high energy big family with large scale Fe emulsion chambers

NASA Technical Reports Server (NTRS)

1985-01-01

In order to get higher efficiencies for detecting hadrons and to make technical improvements in the chamber structure, the Mt. Kambala Emulsion Chamber Collaboration constructed 57 sq. m. of Fe chamber, with thickness 29 c.u.(1c.u.=17.6 mm Fe), using 300 tons of Fe plates and made the first exposure from Sept., 1982 to May, 1984. The photosensitive layers consist of X-ray films of Sakura N type, Fuji No. 100 type and Tianjin III type, some of them contain also emulsion plates of Fuji ET7B type. They are inserted between the Fe plates at 2 c.u., beginning at 5 c.u. from the chamber top. In a number of blocks, 3 mm spacings are provided at every 2 c.u. of Fe plates to facilitate the replacement of photosensitive layers, without disassembling the chamber. On the bottom of the chamber Fe plates of thickness 9 mm are placed in order to shield the chamber from the radioactivities of the ground. An event, numbered K2 58 of visible energy sigma E sub gamma = 7345 TeV was found in this exposure. No obvious halo is seen in the event and all the showers are clearly separated and easy to measure. A brief report of the preliminary results is presented.

Spin-filter spin valves with nano-oxide layers for high density recording heads

NASA Astrophysics Data System (ADS)

Al-Jibouri, Abdul; Hoban, M.; Lu, Z.; Pan, G.

2002-05-01

A new spin-filter spin valve with nano-oxide specular layers with structure of Ta/NiFe/IrMn/CoFe/NOL1/CoFe/Cu/CoFetfl/CutCu/NOL2/Ta was deposited using a Nordiko 9606 physical vapor deposition system. The data clearly show that the magnetoresistive (MR) ratio has been significantly improved for spin valves with thinner free layers. The MR ratio remains larger than 12% even when the CoFe free layer is as thin as 1 nm. An optimized MR ratio of ˜15% was obtained when tfl was about 1.2 nm and tCu about 1.5 nm, and was a result of the balance between the increase in the electron mean free path difference and current shunting through the conducting layer. It is also found that the Cu enhancing layer can improve soft magnetic properties of the CoFe free layer due to the low atomic intermixing observed between Co and Cu. The CoFe free layer of 1-4 nm exhibited coercivity of ˜3 Oe after annealing in a static magnetic field. This kind of spin valve with a very thin soft CoFe free layer is particularly attractive for ultra high density read head applications.

The role of bacterial consortium and organic amendment in Cu and Fe isotope fractionation in plants on a polluted mine site.

PubMed

Pérez Rodríguez, Nathalie; Langella, Francesca; Rodushkin, Ilia; Engström, Emma; Kothe, Erika; Alakangas, Lena; Öhlander, Björn

2014-01-01

Copper and iron isotope fractionation by plant uptake and translocation is a matter of current research. As a way to apply the use of Cu and Fe stable isotopes in the phytoremediation of contaminated sites, the effects of organic amendment and microbial addition in a mine-spoiled soil seeded with Helianthus annuus in pot experiments and field trials were studied. Results show that the addition of a microbial consortium of ten bacterial strains has an influence on Cu and Fe isotope fractionation by the uptake and translocation in pot experiments, with an increase in average of 0.99 ‰ for the δ(65)Cu values from soil to roots. In the field trial, the amendment with the addition of bacteria and mycorrhiza as single and double inoculation enriches the leaves in (65)Cu compared to the soil. As a result of the same trial, the δ(56)Fe values in the leaves are lower than those from the bulk soil, although some differences are seen according to the amendment used. Siderophores, possibly released by the bacterial consortium, can be responsible for this change in the Cu and Fe fractionation. The overall isotopic fractionation trend for Cu and Fe does not vary for pot and field experiments with or without bacteria. However, variations in specific metabolic pathways related to metal-organic complexation and weathering can modify particular isotopic signatures.

Status of neurocognitive and oxidative stress conditions in iron-steel workers.

PubMed

Malekirad, Ali Akbar; Mirabdollahi, Mansuoreh; Pilehvarian, Ali Asghar; Nassajpour, Ali Reza; Abdollahi, Mohammad

2015-07-01

The aim of this study was to determine oxidative stress status as well as ferrous (Fe) and Copper (Cu) levels in blood, neurocognitive impairment, and clinical markers in iron-steel workers. A comparative cross-sectional analysis was performed in 50 iron-steel workers who have been in contact with Fe and Cu in comparison with a control group containing 50 healthy subjects in the same age group and sex. Blood levels of lipid peroxidation, total antioxidant capacity, Fe, and Cu along with neurocognitive impairment were measured in workers and controls. Clinical examination was accomplished to record any abnormal sign or symptoms. Comparing with controls, the workers showed higher blood levels of lipid peroxidation and Cu and also a lower total antioxidant capacity. There was a positive correlation between work history and interstitial lung disease that strengths the presumption to progress to chronic obstructive lung disease in future. The results indicate that exposure to a combination of Fe and Cu in iron-steel workers induces oxidative stress. Especially, in the present case, toxic effect of Cu has been more than positive effects of Fe, but the combined exposure resulted in no such critical toxicity. © The Author(s) 2013.

Research on high Tc superconducting compounds

NASA Technical Reports Server (NTRS)

Oliver, Frederick W. (Principal Investigator)

1996-01-01

Mossbauer research using the 21.54 kev resonance radiation of Eu-151 on the high temperature superconductors Bi(2)Ca(0.5)Eu(0.5)Sr(2)CU2O(x), and EuBa(2)CU(3)O(7-x) is performed. For the Bismuth compound the Mossbauer measurements gave a weak signal at room temperature but improved at lower temperatures. Experimental data indicated that europium is located at only one crystallographic site. Isomer shift measurements were .69 + 0.02 mm/s with respect to EuF(3). The linewidth at room temperature was found to be 2.54 mm/s. This value falls within the values observed by other researchers on Eu based 1,2,3 high-Tc compounds. Our results also show the Eu to be trivalent with no trace of divalent europium present. Superconducting europium based 1,2,3 compounds were prepared and measurements completed. Our results show the Eu to be trivalent with no trace of divalent europium present. These compounds had an average isomer shift of .73 mm/s +/- O.02 for all samples made. One of these was irradiated with 3.5 X 10(exp 16) neutrons and a comparison made of the Mossbauer parameters for the irradiated and non-irradiated samples. Experimental results showed no difference between linewidths but a measurable effect was seen for the isomer shift.

Moessbauer spectra of ferrite catalysts used in oxidative dehydrogenation

NASA Technical Reports Server (NTRS)

Cares, W. R.; Hightower, J. W.

1971-01-01

Room temperature Mossbauer spectroscopy was used to examine bulk changes which occur in low surface area CoFe2O4 and CuFe2O4 catalysts as a result of contact with various mixtures of trans-2-butene and O2 during oxidative dehydrogenation reactions at about 420 C. So long as there was at least some O2 in the gas phase, the CoFe2O4 spectrum was essentially unchanged. However, the spectrum changed from a random spinel in the oxidized state to an inverse spinel as it was reduced by oxide ion removal. The steady state catalyst lies very near the fully oxidized state. More dramatic solid state changes occurred as the CuFe2O4 underwent reduction. Under severe reduction, the ferrite was transformed into Cu and Fe3O4, but it could be reversibly recovered by oxidation. An intense doublet located near zero velocity persisted in all spectra of CuFe2O4 regardless of the state of reduction.

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

NASA Astrophysics Data System (ADS)

Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

2017-05-01

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

Assessment of Quantum Mechanical Methods for Copper and Iron Complexes by Photoelectron Spectroscopy.

PubMed

Niu, Shuqiang; Huang, Dao-Ling; Dau, Phuong D; Liu, Hong-Tao; Wang, Lai-Sheng; Ichiye, Toshiko

2014-03-11

Broken-symmetry density functional theory (BS-DFT) calculations are assessed for redox energetics [Cu(SCH 3 ) 2 ] 1-/0 , [Cu(NCS) 2 ] 1-/0 , [FeCl 4 ] 1-/0 , and [Fe(SCH 3 ) 4 ] 1-/0 against vertical detachment energies (VDE) from valence photoelectron spectroscopy (PES), as a prelude to studies of metalloprotein analogs. The M06 and B3LYP hybrid functionals give VDE that agree with the PES VDE for the Fe complexes, but both underestimate it by ∼400 meV for the Cu complexes; other hybrid functionals give VDEs that are an increasing function of the amount of Hartree-Fock (HF) exchange and so cannot show good agreement for both Cu and Fe complexes. Range-separated (RS) functionals appear to give a better distribution of HF exchange since the negative HOMO energy is approximately equal to the VDEs but also give VDEs dependent on the amount of HF exchange, sometimes leading to ground states with incorrect electron configurations; the LRC- ω PBEh functional reduced to 10% HF exchange at short-range give somewhat better values for both, although still ∼150 meV too low for the Cu complexes and ∼50 meV too high for the Fe complexes. Overall, the results indicate that while HF exchange compensates for self-interaction error in DFT calculations of both Cu and Fe complexes, too much may lead to more sensitivity to nondynamical correlation in the spin-polarized Fe complexes.

Assessment of Quantum Mechanical Methods for Copper and Iron Complexes by Photoelectron Spectroscopy

PubMed Central

2015-01-01

Broken-symmetry density functional theory (BS-DFT) calculations are assessed for redox energetics [Cu(SCH3)2]1–/0, [Cu(NCS)2]1–/0, [FeCl4]1–/0, and [Fe(SCH3)4]1–/0 against vertical detachment energies (VDE) from valence photoelectron spectroscopy (PES), as a prelude to studies of metalloprotein analogs. The M06 and B3LYP hybrid functionals give VDE that agree with the PES VDE for the Fe complexes, but both underestimate it by ∼400 meV for the Cu complexes; other hybrid functionals give VDEs that are an increasing function of the amount of Hartree–Fock (HF) exchange and so cannot show good agreement for both Cu and Fe complexes. Range-separated (RS) functionals appear to give a better distribution of HF exchange since the negative HOMO energy is approximately equal to the VDEs but also give VDEs dependent on the amount of HF exchange, sometimes leading to ground states with incorrect electron configurations; the LRC-ωPBEh functional reduced to 10% HF exchange at short-range give somewhat better values for both, although still ∼150 meV too low for the Cu complexes and ∼50 meV too high for the Fe complexes. Overall, the results indicate that while HF exchange compensates for self-interaction error in DFT calculations of both Cu and Fe complexes, too much may lead to more sensitivity to nondynamical correlation in the spin-polarized Fe complexes. PMID:24803858

An aqueous friendly chemosensor derived from vitamin B6 cofactor for colorimetric sensing of Cu2 + and fluorescent turn-off sensing of Fe3 +

NASA Astrophysics Data System (ADS)

Sharma, Darshna; Kuba, Aman; Thomas, Rini; Kumar, Rajender; Choi, Heung-Jin; Sahoo, Suban K.

2016-01-01

Chemosensor L derived from vitamin B6 cofactor pyridoxal-5-phosphate was investigated for the selective detection of Cu2 + and Fe3 + in aqueous medium. Sensor L formed a 1:1 complex with Cu2 + and displays a perceptible color change from colorless to yellow brown with the appearance of a new charge transfer band at 450 nm. In contrast, the fluorescence of L was quenched selectively in the presence of Fe3 + without any interference from other metal ions including Cu2 +.

Digestibility and retention of zinc, copper, manganese, iron, calcium, and phosphorus in pigs fed diets containing inorganic or organic minerals.

PubMed

Liu, Y; Ma, Y L; Zhao, J M; Vazquez-Añón, M; Stein, H H

2014-08-01

The objective of this experiment was to measure the apparent total tract digestibility (ATTD) and the retention rate of Zn, Cu, Mn, and Fe in pigs fed either inorganic or organic sources of Zn, Cu, Mn, and Fe. The experimental design was a randomized complete block design with a 2 × 3 factorial arrangement of treatments. There were 2 types of diets (corn grits-based or corn-soybean meal [SBM]-based diets) and 3 micromineral treatments (basal micromineral premix [BMM], inorganic micromineral premix [IMM], and organic micromineral premix [OMM]). The BMM contained no added Zn, Cu, Mn, or Fe; the IMM microminerals were provided as sulfates of Zn, Cu, Mn, and Fe at 40, 50, 20, and 100 mg/kg, respectively. The OMM contained the same levels of the 4 microminerals as IMM, but Zn, Cu, Mn, and Fe in this premix were provided by Zn(2-hydroxy-4-methylthio butanoic acid [HMTBa])2, Cu(HMTBa)2, Mn(HMTBa)2, and FeGly, respectively. Forty-eight barrows (initial BW: 31.1 ± 4.2 kg) were housed individually and allowed ad libitum access to the corn grits diet with BMM for 2 wk. All pigs were then moved to metabolism cages and randomly assigned to 1 of the 6 treatment diets with 8 replicates per diet. Fecal and urine samples were collected for 5 d following a 5-d adaptation period. Compared with corn grits diets, pigs fed corn-SBM diets had greater (P < 0.05) absorption and retention of Zn, Cu, and Mn but less (P < 0.05) ATTD of Zn and Cu. Compared with BMM, supplementation of IMM or OMM increased (P < 0.05) absorption, retention, ATTD, and retention rate of Zn, Cu, Mn, and Fe. Compared with IMM, adding OMM to the corn-SBM diet improved (P < 0.05) the absorption and retention of Cu and Mn and the ATTD of Cu, but these differences were not observed in the corn grits diets (interaction, P < 0.05). In addition, adding OMM to the corn-SBM diet increased (P < 0.05) absorption and retention of Zn and Fe and ATTD of Zn, Mn, and Fe compared with adding IMM to the corn-SBM diet. Supplementation of OMM also increased (P < 0.05) the ATTD and retention rate of P in corn-SBM diets. Results indicate that Zn(HMTBa)2 has greater digestibility and Cu(HMTBa)2 and Mn(HMTBa)2 have greater digestibility and retention rates compared with their inorganic sulfates, if included in a corn-SBM diet. Supplementation of organic microminerals also improves the digestibility of P in a corn-SBM diet.

Selective nucleation of iron phthalocyanine crystals on micro-structured copper iodide.

PubMed

Rochford, Luke A; Ramadan, Alexandra J; Heutz, Sandrine; Jones, Tim S

2014-12-14

Morphological and structural control of organic semiconductors through structural templating is an efficient route by which to tune their physical properties. The preparation and characterisation of iron phthalocyanine (FePc)-copper iodide (CuI) bilayers at elevated substrate temperatures is presented. Thin CuI(111) layers are prepared which are composed of isolated islands rather than continuous films previously employed in device structures. Nucleation in the early stages of FePc growth is observed at the edges of islands rather than on the top (111) faces with the use of field emission scanning electron microscopy (FE-SEM). Structural measurements show two distinct polymorphs of FePc, with CuI islands edges nucleating high aspect ratio FePc crystallites with modified intermolecular spacing. By combining high substrate temperature growth and micro-structuring of the templating CuI(111) layer structural and morphological control of the organic film is demonstrated.

Methionine sulphoxide reductases protect iron-sulphur clusters from oxidative inactivation in yeast

PubMed Central

Sideri, Theodora C.; Willetts, Sylvia A.; Avery, Simon V.

2008-01-01

Methionine residues and iron-sulphur (FeS) clusters are primary targets of reactive oxygen species in the proteins of microorganisms. Here we show that methionine redox-modifications help to preserve essential FeS cluster activities in yeast. Mutants defective for the highly conserved methionine sulphoxide reductases (MSRs; which re-reduce oxidized methionines) are sensitive to many pro-oxidants, but here exhibited an unexpected copper resistance. This phenotype was mimicked by methionine sulphoxide supplementation. Microarray analyses highlighted several Cu and Fe homeostasis genes that were upregulated in the mxrΔ double mutant, which lacks both of the yeast MSRs. Of the upregulated genes, the Cu-binding Fe-transporter Fet3p proved to be required for the Cu-resistance phenotype. FET3 is known to be regulated by the Aft1 transcription factor, which responds to low mitochondrial FeS-cluster status. Here, constitutive Aft1p expression in the wild type reproduced the Cu-resistance phenotype, and FeS cluster functions were found to be defective in the mxrΔ mutant. Genetic perturbation of FeS activity also mimicked FET3-dependent Cu resistance. 55Fe-labeling studies showed that FeS clusters are turned over more rapidly in the mxrΔ mutant than the wild type, consistent with elevated oxidative targeting of the clusters in MSR-deficient cells. The potential underlying molecular mechanisms of this targeting are discussed. Moreover, the results indicate an important new role for cellular MSR enzymes, in helping to protect the essential function of FeS clusters in aerobic settings. PMID:19202110

Effect of Si on Fe-rich intermetallic formation and mechanical properties of heat-treated Al–Cu–Mn–Fe alloys

NASA Astrophysics Data System (ADS)

Zhao, Yuliang; Zhang, Weiwen; Yang, Chao; Zhang, Datong; Wang, Zhi

2018-04-01

The effect of Si on Fe-rich intermetallics formation and mechanical properties of heat-treated squeeze cast Al-5.0Cu-0.6Mn-0.7Fe alloy was investigated. Our results show that increasing Si content promotes the formation of Al15(FeMn)3(SiCu)2 (${\\alpha}$-Fe), and varying the morphology of T (Al20Cu3Mn2) where the size decreases and the amount increases. The major reason is that Si promotes heterogeneous nucleation of the intermetallics leading to finer precipitates. Si addition significantly enhances ultimate tensile strength and yield strength of the alloys. The strengthening effect is mainly owing to the dispersoid strengthening by increasing volume fraction of T phase and less harmful ${\\alpha}$-Fe with a compact structure, which make the cracks more difficult to initiate and propagation during tensile test. The squeeze cast Al-5.0Cu-0.6Mn-0.7Fe alloy with 1.1% Si shows significantly improved mechanical properties than the alloy without Si addition, which has tensile strength of 386 MPa, yield strength of 280 MPa and elongation of 8.6%.

Magnetic analysis of a melt-spun Fe-dilute Cu60Ag35Fe5 alloy

NASA Astrophysics Data System (ADS)

Kondo, Shin-ichiro; Kaneko, Kazuhiro; Morimura, Takao; Nakashima, Hiromichi; Kobayashi, Shin-Taro; Michioka, Chishiro; Yoshimura, Kazuyoshi

2015-04-01

The magnetic properties of a melt-spun Fe-dilute Cu60Ag35Fe5 alloy are examined by X-ray diffraction, magnetic measurements, and transmission electron microscopy (TEM). The X-ray diffraction patterns show that the as-spun and annealed (773 K×36 ks) samples contain Cu and Ag phases and no Fe phases; thus, most Fe atoms are dispersed as clusters. Magnetic measurements indicate that the as-spun and annealed samples exhibit superparamagnetic behavior at 300 K, whereas ferromagnetic and superparamagnetic behaviors coexist at 4.2 K. The magnetic moments of small clusters at 300 K are determined by the nonlinear least squares method as 5148 and 4671 μB for as-spun and annealed samples, respectively, whereas those at 300 K are experimentally determined as 3500 and 3200 μB. This decrease in magnetic moments may imply the formation of anti-ferromagnetic coupling by annealing. TEM observation of the melt-spun sample suggests that there are three regions with different compositions: Cu-rich, Ag-rich, and Fe-rich with no precipitation in the matrix. In addition, these regions have obscure interfaces. The magnetic clusters are attributed to the Fe-rich regions.

Investigation of Cu-, Zn- and Fe-containing human brain proteins using isotopic-enriched tracers by LA-ICP-MS and MALDI-FT-ICR-MS

NASA Astrophysics Data System (ADS)

Becker, J. Susanne; Zoriy, Miroslav; Pickhardt, Carola; Przybylski, Michael; Becker, J. Sabine

2005-04-01

Identification of metal-containing proteins and determination of Cu, Fe, Zn concentration in very small protein volumes is of increasing importance in protein research. Proteins containing metal ions were analyzed directly and simultaneously in separated protein spots in two-dimensional gels (2D gels) by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as an element mass spectrometric technique. In order to study the formation of proteins containing Cu, Zn and Fe in a human brain sample, isotopic-enriched tracers (54Fe, 65Cu and 67Zn) were doped to two-dimensional gels of separated Alzheimer-diseased brain proteins after two-dimensional (2D) gel electrophoresis. The protein spots were screened systematically by LA-ICP-MS with respect to these metal ion intensities. 54Fe/56Fe, 65Cu/63Cu and 67Zn/64Zn isotope ratios in metal-containing proteins were measured directly by LA-ICP-MS. The isotope ratio measurements obtained by LA-ICP-MS indicate certain protein spots with a natural isotope composition of Cu, Zn and/or Fe. These proteins already contained the metal investigated in the original proteins and are stable enough to survive the reducing conditions during gel electrophoresis. On the other hand, proteins with a changed isotope ratio of metals in comparison to the isotope ratio in nature demonstrate the accumulation of tracers within the protein complexes during the tracer experiments in 2D gels. The identification of singular protein spots from Alzheimer-diseased brain separated by 2D gel electrophoresis was attempted by biopolymer mass spectrometry using MALDI-FTICR-MS after excision from the 2D gel and tryptic digestion.

Partitioning of Cu between mafic minerals, Fe-Ti oxides and intermediate to felsic melts

NASA Astrophysics Data System (ADS)

Liu, Xingcheng; Xiong, Xiaolin; Audétat, Andreas; Li, Yuan

2015-02-01

This study used improved capsule technique i.e., Pt95Cu05 or Au95Cu05 alloy capsules as Cu sources to determine Cu partitioning between mafic minerals, Fe-Ti oxides and intermediate to felsic melts at 0.5-2.5 GPa, 950-1100 °C and various oxygen fugacities (fO2). In combination with the data from the mafic composition systems, the results demonstrate that Cu is generally highly incompatible in mafic minerals and moderately incompatible to compatible in Fe-Ti oxides. The general order of mineral/melt Cu partition coefficients (DCu) is garnet (0.01-0.06) ⩽ olivine (0.04-0.20) ≈ opx (0.04-0.24) ≈ amphibole (0.04-0.20) ⩽ cpx (0.04-0.45) ⩽ magnetite, titanomagnetite and Cr-spinel (0.18-1.83). The variations in DCu depend mainly on temperature, fO2 or mineral composition. In general, DCu for olivine (and perhaps opx) increases with decreasing temperature and increasing fO2. DCu increases for cpx with Na+ (pfu) in cpx, for magnetite and Cr-spinel with Fe3+ (pfu) in these phases and for titanomagnetite with Ti4+ (pfu) in this phase. The large number of DCu data (99 pairs) serves as a foundation for quantitatively understanding the behavior of Cu during magmatic processes. The generation of intermediate to felsic magmas via fractional crystallization or partial melting of mafic rocks (magmas) at deep levels of crust involves removal of or leaving assemblages of mafic minerals + Fe-Ti oxides ± sulfides. With our DCu data on mafic minerals and Fe-Ti oxides, DCubulk values around 0.2 were obtained for the sulfide-free assemblages. Cu will thus be concentrated efficiently in the derived melts during these two processes if sulfides are absent or negligible, explaining that high fO2 and sulfide-destabilization are favorable to formation of the porphyry Cu system.

Effects of microstructure and CaO addition on the magnetic and mechanical properties of NiCuZn ferrites

NASA Astrophysics Data System (ADS)

Wang, Sea-Fue; Hsu, Yung-Fu; Liu, Yi-Xin; Hsieh, Chung-Kai

2015-11-01

In this study, the effects of grain size and the addition of CaCO3 on the magnetic and mechanical properties of Ni0.5Cu0.3Zn0.2Fe2O4 ceramics were investigated. The bending strength of the ferrites increased from 66 to 84 MPa as the grain size of the sintered ceramics decreased from 10.25 μm to 7.53 μm, while the change in hardness was insignificant. The addition of various amounts of CaCO3 densified the Ni0.5Cu0.3Zn0.2Fe2O4 ceramics at 1075 °C. In the pure Ni0.5Cu0.3Zn0.2Fe2O4 ceramic, second phase CuO was segregated at the grain boundaries. With the CaCO3 content ≥1.5 wt%, a small amount of discrete plate-like second phase Fe2CaO4 was observed, together with the disappearance of the second phase CuO. The grain size of the Ni0.5Cu0.3Zn0.2Fe2O4 ceramic dropped from 7.80 μm to 4.68 μm, and the grain size distribution widened as the CaCO3 content increased from 0 to 5 wt%. Initially rising to 807 after CaCO3 addition up to 2.0 wt%, due to a reduced grain size, the Vickers hardness began to drop as the CaCO3 content increased. The bending strength grew linearly with the CaCO3 content and reached twice the value for the Ni0.5Cu0.3Zn0.2Fe2O4 ceramic with an addition of 5.0 wt% CaCO3. The initial permeability of the Ni0.5Cu0.3Zn0.2Fe2O4 ceramic decreased substantially from 402 to 103 as the addition of CaCO3 in ferrite increased from 0 to 5 wt%, and the quality factor of the Ni0.5Cu0.3Zn0.2Fe2O4 ceramic was maximized at 95 for 1.0 wt% CaCO3 addition.

Self-assembly of an imidazolate-bridged Fe(III)/Cu(II) heterometallic cage.

PubMed

Reichel, Florian; Clegg, Jack K; Gloe, Karsten; Gloe, Kerstin; Weigand, Jan J; Reynolds, Jason K; Li, Chun-Guang; Aldrich-Wright, Janice R; Kepert, Cameron J; Lindoy, Leonard F; Yao, Hong-Chang; Li, Feng

2014-01-21

A rare, discrete, mixed-valent, heterometallic Fe(III)/Cu(II) cage, [Cu6Fe8L8](ClO4)12·χsolvent (H3L = tris{[2-{(imidazole-4-yl)methylidene}amino]ethyl}amine), was designed and synthesized via metal-ion-directed self-assembly with neutral tripodal metalloligands. The formation of this coordination cage was demonstrated by X-ray crystallography, ESI mass spectrometry, FT-IR, and UV-vis-NIR spectroscopy.

The preparation and activity of Cu-Fe-Zr-Ce based catalysts for water gas shift

NASA Astrophysics Data System (ADS)

Wu, H. D.; Liu, T. S.; Liu, H. Z.

2018-01-01

CeO2-ZrO2 composite oxide was synthesized with precipitation method as support and CuaFeb(ZrCe4)8Ox catalysts were prepared by impregnation; X-ray diffraction, H2 temperature program reduction, and scanning electron microscope techniques were jointly used to characterize the crystal phases and reduction properties of catalysts. Then the activity of catalysts in water gas shift was studied, thus investigated how catalyst composition impacted the water gas shift. Conclusions drew from the results can be briefly stated. CuaFeb(ZrCe4)8Ox was provided with stable cubic crystalline framework and Cu and Fe, as the active components, was highly dispersed on the surface of supports in the form of CuO and Fe2O3 respectively. The strong interactions between copper and iron component enhanced the reducing capacity of CuO and Fe2O3. CuaFeb(ZrCe4)8Ox catalysts exhibited high catalytic activity and selectivity while the main active components were Cu and Fe3O4. The CO conversion rate reached 96% when Cu7Fe3(ZrCe4)8Ox catalysts was used in water gas shift at 623K and the only products were H2 and CO2. The activity was still desirable even the catalysts was applied at 723K.

Exposure of women to trace elements through the skin by direct contact with underwear clothing.

PubMed

Nguyen, Thao; Saleh, Mahmoud A

2017-01-02

Heavy metals pose a potential danger to human health when present in textile materials. In the present study, inductive coupled plasma mass spectrometry (ICPMS) was used to determine the concentrations and the identity of extractable inorganic elements from different brands of women undergarments. A total of 120 samples consisting of 63 cottons, 44 nylons and 13 polyesters manufactured in 14 different countries having different colors were analyzed for their extractable metals contents. Elements analyzed were Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Se, Sr, Ti, V and Zn. Cotton undergarments were rich in Al, Fe and Zn, nylon undergarments had high levels of Cr, Cu and Al, while polyester fabrics contained higher levels of Ni and Fe compared to cotton or nylon. With respect to manufacturing countries, China, Egypt and India showed the highest concentrations of metals in all fabrics. With respect to the color, black garments were characteristic by high concentration of Fe, blue colors with Cu, brown garments with Fe and Cu, green garments with Cu and Fe, pink garments with Al, purple garments with Al and Cu and red garments with Cr, Zn and Al. The consumer should be made aware of the potential dangers of these metals in their clothing.

Physical properties of spin-valve films grown on naturally oxidized metal nano-oxide surfaces

NASA Astrophysics Data System (ADS)

Mao, Ming; Cerjan, Charlie; Kools, Jacques

2002-05-01

The physical properties of spin-valve films NiFe 25 Å/CoFe 10 Å/Cu(tCu)/CoFe 30 Å/IrMn 70 Å/Ta 20 Å with graded Cu layer thickness (tCu=18-45 Å) grown on the surface of metal nano-oxide layers (NOLs) were studied. The NOLs were formed from ultrathin Al, Cr, Cu, Nb, Ta, CoFe, NiFe, and NiFeCr layers by natural oxidation. The growth of the spin-valve films on NOLs has led to an enhancement in giant magnetoresistance value by up to 48%. A corresponding reduction in minimum film resistance by over 10% confirms that this enhancement originates from an increase in the mean free path of spin-polarized electrons due to the resultant specular reflection at the nano-oxide surfaces. A wide spectrum of oscillatory interlayer exchange coupling dependence on tCu for these NOL-bearing films suggests that a specular nano-oxide surface does not necessarily result in a smoother multilayer structure. The observation of an enhanced exchange biasing among these spin-valve films appears in contradiction to the observed deterioration of their crystallographic quality. As an important application, TaOx, CrOx, and NbOx could be employed as an alternative to AlOx as the barrier layer for magnetic tunnel junctions.

Metal dynamics in Lake Vanda (Wright Valley, Antarctica)

NASA Technical Reports Server (NTRS)

Green, W. J.; Ferdelman, T. G.; Canfield, D. E.; DeVincenzi, D. L. (Principal Investigator)

1989-01-01

Data are reported for Mn, Fe, Co, Ni, Cu and Cd in the Onyx River, and for Mn, Co, Ni, Cu and Cd in Lake Vanda, a closed-basin Antarctic lake. Oxic water concentrations for Co, Ni, Cu and Cd were quite low and approximate pelagic ocean values. Scavenging of these metals by sinking particles is strongly indicated. Deep-lake profiles reveal a sharp peak in the concentrations of Mn, Fe and Co at the oxic-anoxic boundary at 60 m. Maxima for Ni, Cu and Cd occur higher in the water column, in the vicinity of a Mn submaximum, suggesting early release of these metals from sinking manganese oxide-coated particles. A rough steady-state model leads to the conclusion that there is a large downward flux of Mn into the deep lake and that this flux is sufficient to explain the annual loss of Co, Ni, Cu and Cd. A pronounced geochemical separation between Fe and Mn apparently occurs in this system--Fe being best lost in near-shore environments and Mn being lost in deeper waters. Comparison of metal residence times in Lake Vanda with those in the oceans shows that in both systems Mn, Fe and Co are much more reactive than Ni, Cu and Cd. Energetically favorable inclusion of the more highly charged metals, Mn(IV), Fe(III) and Co(III), into oxide-based lattices is a plausible explanation.

Magnetic properties of (SrFe{sub 12}O{sub 19}){sub x}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 1–x} composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eremina, R. M., E-mail: REremina@yandex.ru; Sharipov, K. R.; Yatsyk, I. V.

2016-07-15

New composite materials (SrFe{sub 12}O{sub 19}){sub x}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 1–x} (x = 0, 0.05, 1) have been synthesized. Their magnetic properties are studied in the temperature range 5–300 K using the magnetic resonance and magnetometry methods. It is found that strontium hexaferrite microinclusions in the (SrFe{sub 12}O{sub 19}){sub 0.05}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 0.95} composite “magnetize” CaCu{sub 3}Ti{sub 4}O{sub 12} at temperatures from 300 to 200 K, forming a ferrimagnetic particle near the SrFe{sub 12}O{sub 19} “core.” The magnetic resonance line below 200 K splits into two lines corresponding to SrFe{sub 12}O{sub 19} and CaCu{sub 3}Ti{sub 4}O{sub 12}. The coremore » effect decoration is manifested in the increase in the Curie–Weiss temperature from 25 K in CaCu{sub 3}Ti{sub 4}O{sub 12} without the doping ceramics to 80 K in the composite with 5% of SrFe{sub 12}O{sub 19}.« less

Room temperature ferromagnetism in Fe-doped CuO nanoparticles.

PubMed

Layek, Samar; Verma, H C

2013-03-01

The pure and Fe-doped CuO nanoparticles of the series Cu(1-x)Fe(x)O (x = 0.00, 0.02, 0.04, 0.06 and 0.08) were successfully prepared by a simple low temperature sol-gel method using metal nitrates and citric acid. Rietveld refinement of the X-ray diffraction data showed that all the samples were single phase crystallized in monoclinic structure of space group C2/c with average crystallite size of about 25 nm and unit cell volume decreases with increasing iron doping concentration. TEM micrograph showed nearly spherical shaped agglomerated particles of 4% Fe-doped CuO with average diameter 26 nm. Pure CuO showed weak ferromagnetic behavior at room temperature with coercive field of 67 Oe. The ferromagnetic properties were greatly enhanced with Fe-doping in the CuO matrix. All the doped samples showed ferromagnetism at room temperature with a noticeable coercive field. Saturation magnetization increases with increasing Fe-doping, becomes highest for 4% doping then decreases for further doping which confirms that the ferromagnetism in these nanoparticles are intrinsic and are not resulting from any impurity phases. The ZFC and FC branches of the temperature dependent magnetization (measured in the range of 10-350 K by SQUID magnetometer) look like typical ferromagnetic nanoparticles and indicates that the ferromagnetic Curie temperature is above 350 K.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Jinlei; Yan, Xu; Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru

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

Syntheses, structures and properties of three new two-dimensional Cu(I)-Ln(III) heterometallic coordination polymers based on 2,2'-dipyridyl-5,5'-dicarboxylate ligands.

PubMed

Zhao, Junwei; Cheng, Yamin; Shang, Sensen; Zhang, Fang; Chen, Li; Chen, Lijuan

2013-12-01

Three new two-dimensional Cu(I)-Ln(III) heterometallic coordination polymers [Ln(III)Cu2(I)(Hbpdc)4] · Cl · xH2O [Ln(III) = La(III), x = 8 (1); Ln(III) = Pr(III), x=9 (2); Ln(III) = Eu(III), x = 8 (3)] (H2bpdc = 2,2'-bipyridyl-5,5'-dicarboxylic acid) have been prepared under hydrothermal conditions and structurally characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP-AES) analyses, IR spectra, X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. X-ray diffraction indicates that the isomorphic 1-3 display the two-dimensional sheet structure constructed from [Cu(I)(Hbpdc)2](-) fragments through Ln(3+) connectors. Moreover, the solid-state photoluminescence measurements of 3 indicate that the Eu(III) ions, Hbpdc(-) ligands and Cu(I) cations make contributions to its luminescent properties simultaneously. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of rare-earth ion size on local electron structure in RBa 2Cu 3O 7- δ (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors: A positron study

NASA Astrophysics Data System (ADS)

Chen, Zhenping; Zhang, Jincang; Su, Yuling; Xue, Yuncai; Cao, Shixun

2006-02-01

The effects of rare-earth ionic size on the local electron structure, lattice parameters and superconductivity have been investigated by positron annihilation technique (PAT) and related experiments for RBa 2Cu 3O 7- δ (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors. The local electron density ne is evaluated as a function of the rare-earth radius. The results show that both the bulk-lifetime τB and the defect lifetime τ2 increase with increasing rare-earth ionic radius, while the local electron density ne decrease with increasing rare-earth ionic radius. These results prove that the changes of ne, the degree of orthorhombic distortion and the coupling between the Cu-O chains and the CuO 2 planes all have an effect on the superconductivity of RBa 2Cu 3O 7- δ systems.

Pressure effects on magnetic pair-breaking in Mn- and Eu-substituted BaFe{sub 2}As{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosa, P. F. S., E-mail: ferrari@ifi.unicamp.br; University of California, Irvine, California 92697-4574; Garitezi, T. M.

2014-05-07

We report a combined study of hydrostatic pressure (P ≤ 25 kbar) and chemical substitution on the magnetic pair-breaking effect in Eu- and Mn-substituted BaFe{sub 2}As{sub 2} single crystals. At ambient pressure, both substitutions suppress the superconducting (SC) transition temperature (T{sub c}) of BaFe{sub 2–x}Co{sub x}As{sub 2} samples slightly under the optimally doped region, indicating the presence of a pair-breaking effect. At low pressures, an increase of T{sub c} is observed for all studied compounds followed by an expected decrease at higher pressures. However, in the Eu dilute system, T{sub c} further increases at higher pressure along with a narrowingmore » of the SC transition, suggesting that a pair-breaking mechanism reminiscent of the Eu Kondo single impurity regime is being suppressed by pressure. Furthermore, Electron Spin Resonance (ESR) measurements indicate the presence of Mn{sup 2+} and Eu{sup 2+} local moments and the microscopic parameters extracted from the ESR analysis reveal that the Abrikosov–Gor'kov expression for magnetic pair-breaking in a conventional sign-preserving superconducting state cannot describe the observed reduction of T{sub c}.« less

Spin dynamics near a putative antiferromagnetic quantum critical point in Cu-substituted BaFe 2 As 2 and its relation to high-temperature superconductivity

DOE PAGES

Kim, M. G.; Wang, M.; Tucker, G. S.; ...

2015-12-02

We present the results of elastic and inelastic neutron scattering measurements on nonsuperconducting Ba(Fe 0.957Cu 0.043) 2As 2, a composition close to a quantum critical point between antiferromagnetic (AFM) ordered and paramagnetic phases. By comparing these results with the spin fluctuations in the low-Cu composition as well as the parent compound BaFe 2As 2 and superconducting Ba(Fe 1–xNi x) 2As 2 compounds, we demonstrate that paramagnon-like spin fluctuations are evident in the antiferromagnetically ordered state of Ba(Fe 0.957Cu 0.043) 2As 2, which is distinct from the AFM-like spin fluctuations in the superconducting compounds. Our observations suggest that Cu substitution decouplesmore » the interaction between quasiparticles and the spin fluctuations. In addition, we show that the spin-spin correlation length ξ(T) increases rapidly as the temperature is lowered and find ω/T scaling behavior, the hallmark of quantum criticality, at an antiferromagnetic quantum critical point.« less

Shock synthesis of quasicrystals with implications for their origin in asteroid collisions.

PubMed

Asimow, Paul D; Lin, Chaney; Bindi, Luca; Ma, Chi; Tschauner, Oliver; Hollister, Lincoln S; Steinhardt, Paul J

2016-06-28

We designed a plate impact shock recovery experiment to simulate the starting materials and shock conditions associated with the only known natural quasicrystals, in the Khatyrka meteorite. At the boundaries among CuAl5, (Mg0.75Fe(2+) 0.25)2SiO4 olivine, and the stainless steel chamber walls, the recovered specimen contains numerous micron-scale grains of a quasicrystalline phase displaying face-centered icosahedral symmetry and low phason strain. The compositional range of the icosahedral phase is Al68-73Fe11-16Cu10-12Cr1-4Ni1-2 and extends toward higher Al/(Cu+Fe) and Fe/Cu ratios than those reported for natural icosahedrite or for any previously known synthetic quasicrystal in the Al-Cu-Fe system. The shock-induced synthesis demonstrated in this experiment reinforces the evidence that natural quasicrystals formed during a shock event but leaves open the question of whether this synthesis pathway is attributable to the expanded thermodynamic stability range of the quasicrystalline phase at high pressure, to a favorable kinetic pathway that exists under shock conditions, or to both thermodynamic and kinetic factors.

Shock synthesis of quasicrystals with implications for their origin in asteroid collisions

NASA Astrophysics Data System (ADS)

Asimow, Paul D.; Lin, Chaney; Bindi, Luca; Ma, Chi; Tschauner, Oliver; Hollister, Lincoln S.; Steinhardt, Paul J.

2016-06-01

We designed a plate impact shock recovery experiment to simulate the starting materials and shock conditions associated with the only known natural quasicrystals, in the Khatyrka meteorite. At the boundaries among CuAl5, (Mg0.75Fe2+0.25)2SiO4 olivine, and the stainless steel chamber walls, the recovered specimen contains numerous micron-scale grains of a quasicrystalline phase displaying face-centered icosahedral symmetry and low phason strain. The compositional range of the icosahedral phase is Al68-73Fe11-16Cu10-12Cr1-4Ni1-2 and extends toward higher Al/(Cu+Fe) and Fe/Cu ratios than those reported for natural icosahedrite or for any previously known synthetic quasicrystal in the Al-Cu-Fe system. The shock-induced synthesis demonstrated in this experiment reinforces the evidence that natural quasicrystals formed during a shock event but leaves open the question of whether this synthesis pathway is attributable to the expanded thermodynamic stability range of the quasicrystalline phase at high pressure, to a favorable kinetic pathway that exists under shock conditions, or to both thermodynamic and kinetic factors.

Coupling catalytic hydrolysis and oxidation of HCN over HZSM-5 modified by metal (Fe,Cu) oxides

NASA Astrophysics Data System (ADS)

Hu, Yanan; Liu, Jiangping; Cheng, Jinhuan; Wang, Langlang; Tao, Lei; Wang, Qi; Wang, Xueqian; Ning, Ping

2018-01-01

In this work, a series of metal oxides (Fe,Cu) modified HZSM-5 catalysts were synthesized by incipient-wetness impregnation method and then characterized by XRD, N2 adsorption-desorption, H2-TPR, NH3-TPD, UV-vis, FT-IR and XPS measurements. The catalytic hydrolysis and oxidation behaviors toward HCN were investigated. The results indicated that the Fe-Cu/HZSM-5 catalysts exhibited more excellent performence on coupling catalytic hydrolysis and oxidation of HCN than HZSM-5, Fe/HZSM-5, Cu/HZSM-5, and both nearly 100% HCN conversion and 80% N2 selectivity were obtained at about 250 °C. The improved catalytic performance could be ascribed to the creation of highly dispersed iron and copper composites on the surface of the HZSM-5 support, the excellent redox and regulated acid properties of the active ingredients. Moreover, the highly N2 selectivity could be attributed to the good interaction between the Fe and Cu nanocomposites which was facilitated to the NH3-SCR (selective catalytic reduction of NO by NH3) reaction.

The impact of wine components on fractionation of Cu and Fe in model wine systems: Macromolecules, phenolic and sulfur compounds.

PubMed

Kontoudakis, Nikolaos; Smith, Mark; Guo, Anque; Smith, Paul A; Scollary, Geoffrey R; Wilkes, Eric N; Clark, Andrew C

2017-08-01

A variety of techniques have been developed with the ability to measure different forms of metals in wine with the ultimate aim of providing a more accurate indicator of metal induced spoilage of wine. This study was conducted in order to identify which wine components influence the measurement of Cu and Fe in their fractionated and/or electrochemically active forms. The measurement techniques involved detection of labile Cu by stripping potentiometry and fractionation of Cu and Fe by sequential solid phase extraction, with detection by inductively coupled plasma-optical emission spectroscopy. The wine components assessed included those extracted from wine (red wine tannin, white wine protein, white wine polysaccharide, red wine polyphenol, white wine polyphenol), and commercially available monomeric compounds, including phenolic compounds and sulfur-containing compounds. For Cu, only hydrogen sulfide, which is known to induce the formation of Cu(I) sulfide, showed any appreciable influence on the fractionation and electrochemical detection of Cu. This form of Cu was also identified as the major component of red and white wines. For Fe, the fractionation was different for red versus white wine, and influenced significantly by extracted red wine polyphenol, (-)-epicatechin, gallic acid and tartaric acid. The wine components showed more influence on Fe at pH4.00 compared to pH3.25. These results enable a targeted use of these techniques in the assessment of metal-induced spoilage of wine. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influences of annealing temperature on sprayed CuFeO2 thin films

NASA Astrophysics Data System (ADS)

Abdelwahab, H. M.; Ratep, A.; Abo Elsoud, A. M.; Boshta, M.; Osman, M. B. S.

2018-06-01

Delafossite CuFeO2 thin films were successfully prepared onto quartz substrates using simple spray pyrolysis technique. Post annealing under nitrogen atmosphere for 2 h was necessary to form delafossite CuFeO2 phase. The effect of alteration in annealing temperature (TA) 800, 850 and 900 °C was study on structural, morphology and optical properties. The XRD results for thin film annealed at TA = 850 °C show single phase CuFeO2 with rhombohedral crystal system and R 3 bar m space group with preferred orientation along (0 1 2). The prepared copper iron oxide thin films have an optical transmission ranged ∼40% in the visible region. The optical direct optical band gap of the prepared thin films was ranged ∼2.9 eV.

Improved Epitaxy and Surface Morphology in YBa2Cu3Oy Thin Films Grown on Double Buffered Si Wafers

NASA Astrophysics Data System (ADS)

Gao, J.; Kang, L.; Wong, H. Y.; Cheung, Y. L.; Yang, J.

Highly epitaxial thin films of YBCO have been obtained on silicon wafers using a Eu2CuO4/YSZ (yttrium-stabilized ZrO2) double buffer. Our results showed that application of such a double buffer can significantly enhance the epitaxy of grown YBCO. It also leads to an excellent surface morphology. The average surface roughness was found less than 5 nm in a large range. The results of X-ray small angle reflection and positron spectroscpy demonstrate a very clear and flat interface between YBCO and buffer layers. The Eu2CuO4/YSZ double buffer could be promising for coating high-TC superconducting films on various reactive substrates.

Chemical characterization of gas- and oil-bearing shales by instrumental neutron activation analysis

USGS Publications Warehouse

Frost, J.K.; Koszykowski, R.F.; Klemm, R.C.

1982-01-01

The concentration of As, Ba, Ca, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, K, La, Lu, Mn, Mo, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U, Yb, and Zn were determined by instrumental neutron activation analysis in block shale samples of the New Albany Group (Devonian-Mississippian) in the in the Illinois Basin. Uranium content of the samples was as high as 75 ppm and interfered in the determination of samarium, molybdenum, barium and cerium. In the determination of selenium a correction was made for interference from tantalum. U, As, Co, Mo, Ni and Sb as well as Cu, V and pyritic sulphur which were determined by other methods, were found to correlate positively with the organic carbon content of the samples. ?? 1982 Akade??miai Kiado??.

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.

Electronic transport properties of MFe2As2 (M = Ca, Eu, Sr) at ambient and high pressures up to 20 GPa

NASA Astrophysics Data System (ADS)

Morozova, Natalia V.; Karkin, Alexander E.; Ovsyannikov, Sergey V.; Umerova, Yuliya A.; Shchennikov, Vladimir V.; Mittal, R.; Thamizhavel, A.

2015-12-01

We experimentally investigated the electronic transport properties of four iron pnictide crystals, namely, EuFe2As2, SrFe2As2, and CaFe2As2 parent compounds, and superconducting CaFe1.94Co0.06As2 at ambient and high pressures up to 20 GPa. At ambient pressure we examined the electrical resistivity, Hall and magnetoresistance effects of the samples in a temperature range from 1.5 to 380 K in high magnetic fields up to 13.6 T. In this work we carried out the first simultaneous investigations of the in-plane and out-of-plane Hall coefficients, and found new peculiarities of the low-temperature magnetic and structural transitions that occur in these materials. In addition, the Hall coefficient data suggested that the parent compounds are semimetals with a multi-band conductivity that includes hole-type and electron-type bands. We measured the pressure dependence of the thermoelectric power (the Seebeck effect) of these samples up to 20 GPa, i.e. across the known phase transition from the tetragonal to the collapsed tetragonal lattice. The high-pressure behavior of the thermopower of EuFe2As2 and CaFe2As2 showing the p-n sign inversions was consistent with the semimetal model described above. By means of thermopower, we found in single-crystalline CaFe2As2 direct evidence of the band structure crossover related to the formation of As-As bonds along the c-axis on the tetragonal → collapsed tetragonal phase transition near 2 GPa. We showed that this feature is distinctly observable only in high-quality samples, and already for re-pressurization cycles this crossover was strongly smeared because of the moderate deterioration of the sample. We also demonstrated by means of thermopower that the band structure crossover that should accompany the tetragonal → collapsed tetragonal phase transition in EuFe2As2 near 8 GPa is hardly visible even in high-quality single crystals. This behavior may be related to a gradual valence change of the Eu ions under pressure that leads to an injection of free electrons and the steady shift of the conduction to n-type.

Distribution of Ca, Fe, Cu and Zn in primary colorectal cancer and secondary colorectal liver metastases

NASA Astrophysics Data System (ADS)

Al-Ebraheem, A.; Mersov, A.; Gurusamy, K.; Farquharson, M. J.

2010-07-01

A microbeam synchrotron X-ray fluorescence (μSRXRF) technique has been used to determine the localization and the relative concentrations of Zn, Cu, Fe and Ca in primary colorectal cancer and secondary colorectal liver metastases. 24 colon and 23 liver samples were examined, all of which were formalin fixed tissues arranged as microarrays of 1.0 mm diameter and 10 μm thickness. The distribution of these metals was compared with light transmission images of adjacent sections that were H and E stained to reveal the location of the cancer cells. Histological details were provided for each sample which enable concentrations of all elements in different tissue types to be compared. In the case of liver, significant differences have been found for all elements when comparing tumour, normal, necrotic, fibrotic, and blood vessel tissues (Kruskal Wallis Test, P<0.0001). The concentrations of all elements have also been found to be significantly different among tumour, necrotic, fibrotic, and mucin tissues in the colon samples (Kruskal Wallis Test, P<0.0001). The concentrations of all elements have been compared between primary colorectal samples and colorectal liver metastases. Concentration of Zn, Cu, Fe and Ca are higher in all types of liver tissues compared to those in the colon tissues. Comparing liver tumour and colon tumour samples, significant differences have been found for all elements (Mann Whitney, P<0.0001). For necrotic tissues, significant increase has been found for Zn, Ca, Cu and Fe (Mann Whitney, P<0.0001 for Fe and Zn, 0.014 for Ca, and 0.001 for Cu). The liver fibrotic levels of Zn, Ca, Cu and Fe were higher than the fibrotic colon areas (independent T test, P=0.007 for Zn and Mann Whitney test P<0.0001 for Cu, Fe and Ca). For the blood vessel tissue, the analysis revealed that the difference was only significant for Fe ( P=0.009) from independent T test.

Ni exposure impacts the pool of free Fe and modifies DNA supercoiling via metal-induced oxidative stress in Escherichia coli K-12.

PubMed

Gault, Manon; Effantin, Géraldine; Rodrigue, Agnès

2016-08-01

The biology of nickel has been widely studied in mammals because of its carcinogenic properties, whereas few studies have been performed in microorganisms. In the present work, changes accompanying stress caused by nickel were evaluated at the cellular level using RNA-Seq in Escherichia coli K-12. Interestingly, a very large number of genes were found to be deregulated by Ni stress. Iron and oxidative stress homeostasis maintenance were among the most highly enriched functional categories, and genes involved in periplasmic copper efflux were among the most highly upregulated. These results suggest that the deregulation of Fe and Cu homeostatic genes is caused by a release of free Cu and Fe ions in the cell which in turn activate the Cu and Fe homeostatic systems. The content of Cu was not significantly affected upon the addition of Ni to the growth medium, nor were the Cus and CopA Cu-efflux systems important for the survival of bacteria under Ni stress In contrast the addition of Ni slightly decreased the amount of cellular Fe and activated the transcription of Fur regulated genes in a Fur-dependent manner. Cu or Fe imbalance together with oxidative stress might affect the structure of DNA. Further experiments revealed that Ni alters the state of DNA folding by causing a relaxed conformation, a phenomenon that is reversible by addition of the antioxidant Tiron or the Fe chelator Dip. The Tiron-reversible DNA relaxation was also observed for Fe and to a lesser extent with Cu but not with Co. DNA supercoiling is well recognized as an integral aspect of gene regulation. Moreover our results show that Ni modifies the expression of several nucleoid-associated proteins (NAPs), important agents of DNA topology and global gene regulation. This is the first report describing the impact of metal-induced oxidative on global regulatory networks. Copyright © 2016 Elsevier Inc. All rights reserved.

Influence of Oxygen on Cu Distribution Behavior Between Molten Iron and FeS-Based Flux

NASA Astrophysics Data System (ADS)

Kang, Youngjo; Shin, Kil-Sun; Morita, Kazuki

2018-06-01

Cu distribution behavior between molten iron and a sulfide flux was investigated under different oxygen contents in the sulfide flux to clarify the effect of oxygen content in FeS-based flux on Cu removal. The activity coefficient of CuS0.5 could be experimentally estimated according to the oxygen content. Based on the present result, the possibility of Cu removal by sulfide flux containing a certain amount of oxide was discussed.

Reaction Mechanisms of Metals with Hydrogen Sulfide and Thiols in Model Wine. Part 2: Iron- and Copper-Catalyzed Oxidation.

PubMed

Kreitman, Gal Y; Danilewicz, John C; Jeffery, David W; Elias, Ryan J

2016-05-25

Sulfidic off-odors arising during wine production are frequently removed by Cu(II) fining. In part 1 of this study ( 10.1021/acs.jafc.6b00641 ), the reaction of H2S and thiols with Cu(II) was examined; however, the interaction of iron and copper is also known to play an important synergistic role in mediating non-enzymatic wine oxidation. The interaction of these two metals in the oxidation of H2S and thiols (cysteine, 3-sulfanylhexan-1-ol, and 6-sulfanylhexan-1-ol) was therefore examined under wine-like conditions. H2S and thiols (300 μM) were reacted with Fe(III) (100 or 200 μM) alone and in combination with Cu(II) (25 or 50 μM), and concentrations of H2S and thiols, oxygen, and acetaldehyde were monitored over time. H2S and thiols were shown to be slowly oxidized in the presence of Fe(III) alone and were not bound to Fe(III) under model wine conditions. However, Cu(II) added to model wine containing Fe(III) was quickly reduced by H2S and thiols to form Cu(I) complexes, which then rapidly reduced Fe(III) to Fe(II). Oxidation of Fe(II) in the presence of oxygen regenerated Fe(III) and completed the iron redox cycle. In addition, sulfur-derived oxidation products were observed, and the formation of organic polysulfanes was demonstrated.

Evaluation of metal mobility from copper mine tailings in northern Chile.

PubMed

Lam, Elizabeth J; Gálvez, M E; Cánovas, M; Montofré, I L; Rivero, D; Faz, A

2016-06-01

This work shows the results obtained on a copper mine tailing in the Antofagasta Region, Chile. The tailing was classified as saline-sodic with high concentrations of metals, especially Cu and Fe, with pH 8.4. Our objectives were to (1) compare the physicochemical properties of the tailing with surrounding soils of the mine under study, and (2) evaluate the effect of two amendments (CaCO3 and compost) and their mixtures on Cu(2+), Mn, Fe, Zn, Mg(2+), and K(+) and Ca(2+), SO4 (2-), NO3 (-), and PO4 (3-) leaching. The data obtained were submitted to variance and covariance analysis. The results from the comparison between both substrates showed that in general, the tailing presented greater content of metals. Regarding tailing leaching, pH, electrical conductivity (EC), and concentration of the elements of interest were measured. The statistical analysis showed that Cu(2+) leaching and immobilization of Fe occurred to the greatest extent with compost. The EC decreased throughout the experiment with irrigation and increased upon treatment with compost. The major interactions found among the chemical parameters were (1) tailings without treatment, Cu(2+)/Fe and NO3 (-)/SO4 (2-); (2) tailings treated with CaCO3, Cu(2+)/K(+); (3) tailings treated with compost, NO3 (-)/SO4 (-2) and EC/Cu(2+); and (4) tailings treated with both amendments, EC/Fe and Cu(2+)/Fe. The ANOVA showed that the number of irrigations and the amendments statistically significantly affected the copper mobility and the organic amendment significantly influenced the iron mobility.

Highly visible-light-responsive Cu2O/rGO decorated with Fe3O4@SiO2 nanoparticles as a magnetically recyclable photocatalyst

NASA Astrophysics Data System (ADS)

Liu, Shou-Heng; Lu, Jun-Sheng; Yang, Sheng-Wei

2018-07-01

The rhombic dodecahedral cuprous oxide-reduced graphene oxide/core–shell Fe3O4@SiO2 composites (denoted as rCu2O-rGO/Fe3O4@SiO2) are successfully synthesized facilely via a wet-chemical route. The resulting rCu2O-rGO/Fe3O4@SiO2 combines the unique structure of Cu2O, electronic characteristics of reduced graphene oxide (rGO) and magnetic property of Fe3O4@SiO2 to be an effective and recoverable photocatalyst for the degradation of methyl orange (MO). The obtained results show that rCu2O-rGO/Fe3O4@SiO2 is capable of completely degrading MO in the presence of a very low catalyst concentration (0.125 g l‑1) within a short time (60 min) under visible light compared to the reported catalysts. The observations may be due to the distinctive interfacial structures of rhombic dodecahedral Cu2O nanoparticles connected to rGO sheets that can enhance the separation of photogenerated electron–hole pairs, stabilize the Cu2O and increase MO adsorption, as evidenced by a variety of spectroscopic analyses (transmission electron microscopy, x-ray photoelectron spectroscopy and photoluminescence). More importantly, these efficient photocatalysts can easily be recovered under a magnetic field and remain highly photoactive towards the degradation of MO after cyclic tests, and may be promising photocatalysts for practical applications in the solar-energy purification of wastewater.

Highly visible-light-responsive Cu2O/rGO decorated with Fe3O4@SiO2 nanoparticles as a magnetically recyclable photocatalyst.

PubMed

Liu, Shou-Heng; Lu, Jun-Sheng; Yang, Sheng-Wei

2018-07-27

The rhombic dodecahedral cuprous oxide-reduced graphene oxide/core-shell Fe 3 O 4 @SiO 2 composites (denoted as rCu 2 O-rGO/Fe 3 O 4 @SiO 2 ) are successfully synthesized facilely via a wet-chemical route. The resulting rCu 2 O-rGO/Fe 3 O 4 @SiO 2 combines the unique structure of Cu 2 O, electronic characteristics of reduced graphene oxide (rGO) and magnetic property of Fe 3 O 4 @SiO 2 to be an effective and recoverable photocatalyst for the degradation of methyl orange (MO). The obtained results show that rCu 2 O-rGO/Fe 3 O 4 @SiO 2 is capable of completely degrading MO in the presence of a very low catalyst concentration (0.125 g l -1 ) within a short time (60 min) under visible light compared to the reported catalysts. The observations may be due to the distinctive interfacial structures of rhombic dodecahedral Cu 2 O nanoparticles connected to rGO sheets that can enhance the separation of photogenerated electron-hole pairs, stabilize the Cu 2 O and increase MO adsorption, as evidenced by a variety of spectroscopic analyses (transmission electron microscopy, x-ray photoelectron spectroscopy and photoluminescence). More importantly, these efficient photocatalysts can easily be recovered under a magnetic field and remain highly photoactive towards the degradation of MO after cyclic tests, and may be promising photocatalysts for practical applications in the solar-energy purification of wastewater.

Enhanced magnetoimpedance and field sensitivity in microstructure controlled FeSiCuNbB ribbons

NASA Astrophysics Data System (ADS)

Sahoo, Trilochan; Chandra Mishra, Amaresh; Srinivas, V.; Nath, T. K.; Srinivas, M.; Majumdar, B.

2011-10-01

Fe73.5Si13.5Cu1Nb3B9 and Fe77.2Si11.2Cu0.8Nb3.3B7.5 nanocomposite materials consisting of nanocrystalline phase in an amorphous matrix were obtained by heat-treatment of their precursor amorphous ribbons. The influence of structural modifications induced during the heat-treatment on soft magnetic properties and magnetoimpedance (MI) effect have been studied. The structural investigations on both these ribbons revealed the presence of two phases, fine grained Fe3Si phase and a residual amorphous phase on heat-treatment. The maximum MI ratio obtained in the present study is 95% at f = 4 MHz, for the optimized heat-treated Fe77.2Si11.2Cu0.8Nb3.3B7.5 ribbon. This is ascribed to the increase in magnetic permeability and decrease in coercive force and intrinsic resistivity. Moreover, a maximum magnetic field sensitivity (ξ) of 8.3%/Oe at f = 2.5 MHz is obtained, for the optimized nanocrystalline Fe73.5Si13.5Cu1Nb3B9 ribbon. This suggests that tailoring of the nanocrystalline microstructures induced by optimum heat-treatment conditions can result in obtaining excellent combinations of the magnetic permeability and resistivity. Our results indicate that these Fe-based nanocrystalline materials can be ideally used for low magnetic field and high frequency sensor applications.

ONR Tokyo Scientific Bulletin. Volume 5, Number 1, January-March 1980,

DTIC Science & Technology

1980-03-01

alloys studied are in die AI-Zn, Al -Mg, Al -Si. Al - Cu . Cu - Al . and Cu -Fe... alloys Digital processing Measuring N 20. Abstract (cont.) with certain reports also being contributed by visiting stateside scientist. Occasionally a...atomic absorption spectrophotometer with tubes for the determination of Zn, Cu , Pb, Cr, Fe, Mg, Mn, Al , Co, Cd, Si, Ti, Zr, Ga, Au, Ag, Ni, Na, and

Cu(II) removal by Anoxybacillus flavithermus-iron oxide composites during the addition of Fe(II)aq

NASA Astrophysics Data System (ADS)

Franzblau, Rachel E.; Daughney, Christopher J.; Swedlund, Peter J.; Weisener, Christopher G.; Moreau, Magali; Johannessen, Bernt; Harmer, Sarah L.

2016-01-01

There is currently poor understanding of metal removal by composites of bacteria and iron oxide minerals, even though they commonly co-occur and are among the most important sorbents in near-surface fluid-rock environments. This study evaluated Cu removal by composites of Anoxybacillus flavithermus and iron oxide over time during the addition, oxidation, and hydrolysis of Fe(II)aq and precipitation of the mineral, in comparison to Cu removal in the two single-sorbent end-member systems. In the absence of iron oxide, Cu removal by A. flavithermus was well described by a previously published surface complexation model, after inclusion of additional reactions describing aqueous complexation by exudate ligands released by the bacteria. In the absence of bacterial cells, Cu removal by iron oxide synthesized in the presence of the bacterial exudate ligands demonstrated the formation of ternary surface complexes. Removal of Cu by the A. flavithermus-iron oxide composites was ca. 20% greater than the prediction based on assumption of additivity in the two end-member systems. This non-additive behavior was attributed to (1) progressive physical blockage of bacterial surface sites by the iron oxide particles, (2) physical blockage of adsorption sites as a result of self-aggregation of the iron oxide particles, and (3) the reduction of Cu(II) to Cu(I) at the bacterial cell surface, as demonstrated by X-ray absorption spectroscopy. The extent of reduction of Cu(II) to Cu(I) was proportional to the concentration of solid phase Fe(II), suggesting that iron oxidation and copper reduction are linked. This study has shown that Cu removal by bacteria-iron oxide composites is greatly affected by redox processes such as Cu(II) reduction on the cell surface both by other bacterial surface ligands and the oxidation of sorbed Fe(II), as well as Fe(II) redox interactions, and aging effects of the mineral (i.e. surface site masking).

New constraints on the origin of the Skaergaard intrusion Cu-Pd-Au mineralization: Insights from high-resolution X-ray computed tomography

NASA Astrophysics Data System (ADS)

Godel, Bélinda; Rudashevsky, Nikolay S.; Nielsen, Troels F. D.; Barnes, Stephen J.; Rudashevsky, Vladimir N.

2014-03-01

This contribution presents the first detailed three-dimensional (3D) in situ analysis of samples from the Platinova Reef using high-resolution X-ray computed tomography (HRXCT) and 3D image processing and quantification coupled with microscopic and mineralogical investigations. Our HRXCT analyses reveal the complex textural relationships between Cu-rich sulfides (bulk composition close to bornite), skaergaardite (PdCu), Au-rich phases, silicates and Fe-Ti oxides and provide unequivocal textural evidences, not observed previously. The association in 3D between Cu-rich sulfide globules, PdCu alloy and ilmenite is inconsistent with a hydrothermal origin of the Cu-Pd mineralization. In contrast, our results combined with phase diagrams strongly support a primary magmatic origin for the Cu-Pd mineralization where Cu and Pd-rich, Fe-poor sulfide liquid represents a cumulus phase that forms by in-situ nucleation. These sulfide droplets and attached skaergaardite grains were trapped during the formation and crystallization of the Fe-Ti oxides. Subsequent, post-cumulus processes led to the partial to total dissolution of the sulfide not entirely enclosed by the Fe-Ti oxides (i.e., not protected from reaction) leading to the observed variability in Cu and Pd composition at the aggregate (sulfide + PdCu) scale and to the occurrence of free PdCu alloys. In contrast to the PdCu alloy, gold-bearing minerals are never observed entirely enclosed within the Fe-Ti oxide. Two hypotheses can be envisaged for the formation of the gold enriched layer in the upper part of the section. Gold may have either precipitated from high-temperature late magmatic Cl-rich fluids. Alternatively, gold may have been enriched during fractional crystallization after sulfide had been suppressed from the liquidus after the Pd layer crystallized and then deposited along redox barriers.

Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst

PubMed Central

Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

2016-01-01

Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as −0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at −0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under −0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination. PMID:27487918

Copper and Iron Homeostasis in Plants: The Challenges of Oxidative Stress

PubMed Central

Pilon, Marinus

2013-01-01

Abstract Significance: Photosynthesis, the process that drives life on earth, relies on transition metal (e.g., Fe and Cu) containing proteins that participate in electron transfer in the chloroplast. However, the light reactions also generate high levels of reactive oxygen species (ROS), which makes metal use in plants a challenge. Recent Advances: Sophisticated regulatory networks govern Fe and Cu homeostasis in response to metal ion availability according to cellular needs and priorities. Molecular remodeling in response to Fe or Cu limitation leads to its economy to benefit photosynthesis. Fe toxicity is prevented by ferritin, a chloroplastic Fe-storage protein in plants. Recent studies on ferritin function and regulation revealed the interplay between iron homeostasis and the redox balance in the chloroplast. Critical Issues: Although the connections between metal excess and ROS in the chloroplast are established at the molecular level, the mechanistic details and physiological significance remain to be defined. The causality/effect relationship between transition metals, redox signals, and responses is difficult to establish. Future Directions: Integrated approaches have led to a comprehensive understanding of Cu homeostasis in plants. However, the biological functions of several major families of Cu proteins remain unclear. The cellular priorities for Fe use under deficiency remain largely to be determined. A number of transcription factors that function to regulate Cu and Fe homeostasis under deficiency have been characterized, but we have not identified regulators that mediate responses to excess. Importantly, details of metal sensing mechanisms and cross talk to ROS-sensing mechanisms are so far poorly documented in plants. Antioxid. Redox Signal. 19, 919–932. PMID:23199018

Doping effects of Co and Cu on superconductivity and magnetism in Fe1+yTe0.6Se0.4 single crystals.

PubMed

Zhang, Z T; Yang, Z R; Li, L; Ling, L S; Zhang, C J; Pi, L; Zhang, Y H

2013-01-23

We report on the investigation of Co and Cu substitution effects on superconductivity and magnetism in Fe(1+y)Te(0.6)Se(0.4) single crystals. The parent Fe(1.01)Te(0.59)Se(0.41) shows a nodeless bulk superconductivity as revealed in heat capacity measurement, which is gradually suppressed by either Co or Cu doping. It is found that the Co or Cu doping mainly serves as scatterers rather than charge carrier doping, which is in agreement with the DFT calculation (2010 Phys. Rev. Lett. 105 157004) reported by Wadati et al. In comparison with Cu doping, Co doping shows a stronger influence on magnetism while a less evident suppression effect on superconductivity. Upon substitution of Co for Fe, a Schottky heat capacity anomaly develops gradually at low temperatures, implying the existence of a paramagnetic moment in the Co-doped samples. In contrast, Cu doping may mainly serve as non-magnetic scatterers, where no Schottky anomaly is observed.

Renierite, Cu10ZnGe2Fe4S16-Cu11GeAsFe4S16: a coupled solid solution series.

USGS Publications Warehouse

Bernstein, L.R.

1986-01-01

The composition of renierite is found to be Cu10(Zn1-xCux)Ge2-xAsxFe4S16 (0 = or < x = or < 1), with continuous solid solution between the zincian and arsenian end-members, Cu10ZnGe2Fe4S16 and Cu11GeAsFe4S16, through the coupled substitution Zn(II) + Ge(IV) = Cu(I) + As(V). This is the first reported example of extensive coupled solid solution in a sulphide mineral. Arsenian renierite, not previously characterized, is similar to zincian renierite in polished section, with a slightly redder colour and lower anisotropy. It is reddish orange with relief very similar to that of bornite, though it is harder (VHN25 = 286) and does not tarnish in air. It is slightly bireflective, with colours varying from orange-yellow to reddish orange in nearly crossed polarizers. The strongest powder XRD lines are: 3.042(100), 1.861(29), 1.869(16), 1.594(11) and 1.017(10) A; D(calc.) 4.50 g/cm3. Specimens have been found at the Ruby Creek copper deposit, Alaska, where zincian renierite also occurs, and at the Inexco no. 1 mine, Jamestown, Colorado.-J.A.Z.

High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey

NASA Astrophysics Data System (ADS)

Jacobson, Heather R.; Keller, Stefan; Frebel, Anna; Casey, Andrew R.; Asplund, Martin; Bessell, Michael S.; Da Costa, Gary S.; Lind, Karin; Marino, Anna F.; Norris, John E.; Peña, José M.; Schmidt, Brian P.; Tisserand, Patrick; Walsh, Jennifer M.; Yong, David; Yu, Qinsi

2015-07-01

The SkyMapper Southern Sky Survey is carrying out a search for the most metal-poor stars in the Galaxy. It identifies candidates by way of its unique filter set which allows for estimation of stellar atmospheric parameters. The set includes a narrow filter centered on the Ca ii K 3933 Å line, enabling a robust estimate of stellar metallicity. Promising candidates are then confirmed with spectroscopy. We present the analysis of Magellan Inamori Kyocera Echelle high-resolution spectroscopy of 122 metal-poor stars found by SkyMapper in the first two years of commissioning observations. Forty-one stars have [{Fe}/{{H}}]≤slant -3.0. Nine have [{Fe}/{{H}}]≤slant -3.5, with three at [{Fe}/{{H}}]∼ -4. A 1D LTE abundance analysis of the elements Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, Ba, and Eu shows these stars have [X/Fe] ratios typical of other halo stars. One star with low [X/Fe] values appears to be “Fe-enhanced,” while another star has an extremely large [Sr/Ba] ratio: \\gt 2. Only one other star is known to have a comparable value. Seven stars are “CEMP-no” stars ([{{C}}/{Fe}]\\gt 0.7, [{Ba}/{Fe}]\\lt 0). 21 stars exhibit mild r-process element enhancements (0.3≤slant [{Eu}/{Fe}]\\lt 1.0), while four stars have [{Eu}/{Fe}]≥slant 1.0. These results demonstrate the ability to identify extremely metal-poor stars from SkyMapper photometry, pointing to increased sample sizes and a better characterization of the metal-poor tail of the halo metallicity distribution function in the future. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Mechanisms controlling Cu, Fe, Mn, and Co profiles in peat of the Filson Creek Fen, northeastern Minnesota

USGS Publications Warehouse

Walton-Day, K.; Filipek, L.H.; Papp, C.S.E.

1990-01-01

Filson Creek Fen, located in northeastern Minnesota, overlies a Cu-Ni sulfide deposit. A site in the fen was studied to evaluate the hydrogeochemical mechanisms governing the development of Fe, Mn, Co, and Cu profiles in the peat. At the study site, surface peat approximately 1 m thick is separated from the underlying mineralized bedrock by a 6-12 m thickness of lake and glaciofluvial sediments and till. Concentrations of Fe, Mn, Co, and Cu in peat and major elements in pore water delineate a shallow, relatively oxidized, Cu-rich zone overlying a deeper, reduced, Fe-, Mn-, and Co-rich zone within the peat. Sequential metal extractions from peat samples reveal that 40-55% of the Cu in the shallow zone is associated with organic material, whereas the remaining Cu is distributed between iron-oxide, sulfide, and residual fractions. Sixty to seventy percent of the Fe, Mn, and Co concentrated in the deeper zone occur in the residual phase. The metal profiles and associations probably result from non-steady-state input of metals and detritus into the fen during formation of the peat column. The enrichment of organic-associated Cu in the upper, oxidized zone represents a combination of Cu transported into the fen with detrital plant fragments and soluble Cu, derived from weathering of outcrop and subcrop of the mineral deposit, transported into the fen, and fixed onto organic matter in the peat. The variable stratigraphy of the peat indicates that weathering processes and surface vegetation have changed through time in the fen. The Fe, Mn, and Co maxima at the base of the peat are associated with a maximum in detrital matter content of the peat resulting from a transition between the underlying inorganic sedimentary environment to an organic sedimentary environment. The chemistry of sediments and ground water collected beneath the peat indicate that mobilization of metals from sulfide minerals in the buried mineral deposit or glacial deposits is minimal. Therefore, the primary source of Cu to the peat at the study site is outcrops and shallow subcrops of the mineral deposit adjacent to the fen. ?? 1990.

Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

2012-08-01

Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban Environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time (1 h) and size (PM2.5 particulate matter <2.5 μm) resolved Particle Induced X-ray Emission (PIXE) measurements. In the Marie Curie FP7-EU framework of SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), the unique approach used is the simultaneous PIXE measurements at two monitoring sites: urban background (UB) and a street canyon traffic road site (RS). Elements related to primary non exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (secondary sulphate (S) - 27%, biomass burning (K) - 5%, sea salt (Na-Mg) - 17%), three types of dust aerosols (soil dust (Al-Ti) - 17%, urban crustal dust (Ca) - 6%, and primary traffic non exhaust brake dust (Fe-Cu) - 7%), and three types industrial aerosol plumes-like events (shipping oil combustion (V-Ni) - 17%, industrial smelters (Zn-Mn) - 3%, and industrial combustion (Pb-Cl) - 5%). The validity of the PMF solution of the PIXE data is supported by strong correlations with external single particle mass spectrometry measurements. Beside apportioning the aerosol sources, some important air quality related conclusions can be drawn about the PM2.5 fraction simultaneously measured at the UB and RS sites: (1) the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2) by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3) a unique source of Pb-Cl (associated with industrial combustion emissions) is found a to be the major (82%) source of Cl in the urban agglomerate; (4) PM2.5 traffic brake dust (Fe-Cu) is mainly primarily emitted and not resuspended, whereas PM2.5 urban crustal dust (Ca) is found mainly resuspended by both traffic vortex and sea breeze; (5) urban dust (Ca) is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing dust concentrations in road sites, far more effective than street sweeping activities.

Structural and magnetic analysis of Cu, Co substituted NiFe2O4 thin films

NASA Astrophysics Data System (ADS)

Sharma, Hakikat; Bala, Kanchan; Negi, N. S.

2016-05-01

In the present work we prepared NiFe2O4, Ni0.95Cu0.05Fe2O4 and Ni0.94Cu0.05Co0.01 Fe2O4 thin films by metallo-organic decomposition method (MOD) using spin coating technique. The thin films were analyzed by X-ray diffractometer (XRD) and Atomic force microscope (AFM) for structural studies. The XRD patterns confirmed the ferrite phase of thin films. From AFM, we analyzed surface morphology, calculated grain size (GS) and root mean square roughness (RMSR). Room temperature magnetic properties were investigated by vibrating sample magnetometer (VSM).

Analysis of micromineral contents of school meals.

PubMed

Shin, Dongsoon

2014-08-01

Korean ordinary diets are referred to be good for human health in worldwide. However it is uncertain whether they provide microminerals enough for growth and health of teenagers. A main purpose of this study was to identify micromineral contents in school meals. The fifty cuisines were collected from elementary schools and middle schools in Gyeongnam area. The contents of Fe, Zn, Cu and Mn among microminerals were analyzed by using ICP-OES method. Data were expressed as mean, standard deviation and range value and linear regression analysis performed. Fe level of Pangibuseotpaprika-salad was the highest among side-dishes (average 346.6 µg) and Zn level of Sullung-tang was highest among soups (average 229.1 µg). Cu level of Buchu-kimchi was the highest among kimchies (average 217.5 µg) and Mn level of Gumeunkongyangnyum-gui was highest among side-dishes (average 198.4 µg). Generally cooked-rices as main dish had relative smaller amounts of microminerals than the other cuisines. The results showed that the ratio of Cu : Fe : Zn was approximately 12 : 4 : 1 and the relationship between Fe versus Zn or Fe versus Cu was significantly positive. Comparing to Korean Dietary Recommended Intakes (KDRI) level, school meals provided not sufficient amount (<25% DRI) of Fe, Zn or Mn, while they did excessive amount (>125% DRI) of Cu.

Cu(2+) and Fe(2+) mediated photodegradation studies of soil-incorporated chlorpyrifos.

PubMed

Rafique, Nazia; Tariq, Saadia R; Ahad, Karam; Taj, Touqeer

2016-03-01

The influences of Cu(2+) and Fe(2+) on the photodegradation of soil-incorporated chlorpyrifos were investigated in the present study. The soil samples spiked with chlorpyrifos and selected metal ions were irradiated with UV light for different intervals of time and analyzed by HPLC. The unsterile and sterile control soil samples amended with pesticides and selected metals were incubated in the dark at 25 °C for the same time intervals. The results of the study evidenced that photodegradation of chlorpyrifos followed the first-order kinetics. The dissipation t0.5 of chlorpyrifos was found to decrease from 41 to 20 days under UV irradiation. The rate of chlorpyrifos photodegradation was increased in the presence of both metals, i.e., Cu(2+) and Fe(2+). Thus, initially observed t0.5 of 19.8 days was decreased to 4.39 days in the case of Cu(+2) and 19.25 days for Fe(+2). Copper was found to increase the rate of photodegradation by 4.5 orders of magnitude while the microbial degradation of chlorpyrifos was increased only twofold. The microbial degradation of chlorpyrifos was only negligibly affected by Fe(2+) amendment. The studied trace metals also affected the abiotic degradation of the pesticide in the order Cu(2+) > Fe(2+).

Copper and cobalt mobility in soil and accumulation in a metallophyte as influenced by experimental manipulation of soil chemical factors.

PubMed

Lange, Bastien; Pourret, Olivier; Meerts, Pierre; Jitaru, Petru; Cancès, Benjamin; Grison, Claude; Faucon, Michel-Pierre

2016-03-01

The influence of Fe oxides, Mn oxides and organic matter (OM) on the Cu and Co mobility in soil and accumulation in the metallophyte Anisopappus chinensis (Ac), as compared with Helianthus annuus (Ha), was experimentally investigated. Growth and accumulation response when increasing the exchangeable Cu and Co concentrations in soil were also investigated. Plants were cultivated on soil where concentrations of Cu, Co, Fe oxides, Mn oxides and OM content were varied according to 36 treatments. The OM supply decreased the Cu mobility and increased the Co mobility, resulting in decreasing the foliar Cu of Ac and increasing the foliar Co of Ha. The Fe oxides supply could increase the Cu accumulation for Ac, but was not verified for Ha. Compared with Ha, Ac increasingly accumulated Cu and Co without negative effect on plant growth while increasing Cu and Co mobility to phytotoxic concentrations. The results revealed promising perspectives for the use of Ac in Cu-contaminated environment phytoremediation applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Engineering nonspherical hollow structures with complex interiors by template-engaged redox etching.

PubMed

Wang, Zhiyu; Luan, Deyan; Li, Chang Ming; Su, Fabing; Madhavi, Srinivasan; Boey, Freddy Yin Chiang; Lou, Xiong Wen

2010-11-17

Despite the significant advancement in making hollow structures, one unsolved challenge in the field is how to engineer hollow structures with specific shapes, tunable compositions, and desirable interior structures. In particular, top-down engineering the interiors inside preformed hollow structures is still a daunting task. In this work, we demonstrate a facile approach for the preparation of a variety of uniform hollow structures, including Cu(2)O@Fe(OH)(x) nanorattles and Fe(OH)(x) cages with various shapes and dimensions by template-engaged redox etching of shape-controlled Cu(2)O crystals. The composition can be readily modulated at different structural levels to generate other interesting structures such as Cu(2)O@Fe(2)O(3) and Cu@Fe(3)O(4) rattles, as well as Fe(2)O(3) and Fe(3)O(4) cages. More remarkably, this strategy enables top-down engineering the interiors of hollow structures as demonstrated by the fabrication of double-walled nanorattles and nanoboxes, and even box-in-box structures. In addition, this approach is also applied to form Au and MnO(x) based hollow structures.

Factors affecting the partitioning of Cu, Zn and Pb in boulder coatings and stream sediments in the vicinity of a polymetallic sulfide deposit

USGS Publications Warehouse

Filipek, L.H.; Chao, T.T.; Carpenter, R.H.

1981-01-01

A sequential extraction scheme is utilized to determine the geochemical partitioning of Cu, Zn and Pb among hydrous Mn- and Fe-oxides, organics and residual crystalline silicates and oxides in the minus-80-mesh ( Fe-oxides > Mn-oxides; Zn, Mn-oxides {reversed tilde equals} organics > Fe-oxides; Pb, Fe-oxides > organics > Mn-oxides. In the sediments, organics are the most efficient scavengers of all three ore metals. These results emphasize the importance of organics as sinks for the ore metals, even in environments with high concentrations of Mn- and Fe-oxides. Of the ore metals, Zn appears to be the most mobile, and is partitioned most strongly into the coatings. However, anomaly contrast for hydromorphic Zn, normalized to the MnFe-oxide or organic content, is similar in sediments and coatings. Cu shows the highest anomaly on the boulder coatings, probably due to precipitation of a secondary Cu mineral. In contrast, detrital Pb in the pan concentrates shows a better anomaly than any hydromorphic Pb component. ?? 1981.

Elemental abundances and classification of carbon-enhanced metal-poor stars

NASA Astrophysics Data System (ADS)

Allen, D. M.; Ryan, S. G.; Rossi, S.; Beers, T. C.; Tsangarides, S. A.

2012-12-01

We present a detailed study of carbon-enhanced metal-poor (CEMP) stars, based on high-resolution spectroscopic observations of a sample of 18 stars. The stellar spectra for this sample were obtained at the 4.2 m William Herschel Telescope in 2001 and 2002, using the Utrecht Echelle Spectrograph, at a resolving power R ~ 52 000 and S/N ~ 40, covering the wavelength range λλ3700-5700 Å. The atmospheric parameters determined for this sample indicate temperatures ranging from 4750 K to 7100 K, log g from 1.5 to 4.3, and metallicities -3.0 ≤ [Fe/H] ≤ -1.7. Elemental abundances for C, Na, Mg, Sc, Ti, Cr, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, Gd, Dy are determined. Abundances for an additional 109 stars were taken from the literature and combined with the data of our sample. The literature sample reveals a lack of reliable abundance estimates for species that might be associated with the r-process elements for about 67% of CEMP stars, preventing a complete understanding of this class of stars, since [Ba/Eu] ratios are used to classify them. Although eight stars in our observed sample are also found in the literature sample, Eu abundances or limits are determined for four of these stars for the first time. From the observed correlations between C, Ba, and Eu, we argue that the CEMP-r/s class has the same astronomical origin as CEMP-s stars, highlighting the need for a more complete understanding of Eu production. Tables 1, 3, 4, 8-10, A.1, and B.1-B.4 are available in electronic form at http://www.aanda.orgFull Tables 2, 5, and 7 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/548/A34

Self-adjusted flux for the traveling solvent floating zone growth of YBaCuFeO5 crystal

NASA Astrophysics Data System (ADS)

Lai, Yen-Chung; Shu, Guo-Jiun; Chen, Wei-Tin; Du, Chao-Hung; Chou, Fang-Cheng

2015-03-01

A modified traveling solvent floating zone (TSFZ) technique was used to successfully grow a large size and high quality single crystal of multiferroic material YBaCuFeO5. This modified TSFZ growth uses a stoichiometric feed rod and pure copper oxide as the initial flux without prior knowledge of the complex phase diagram involving four elements, and the optimal flux for the growth of incongruently melt crystal is self-adjusted after a prolonged stable pulling. The wetting of the feed rod edge that often perturbs the molten zone stability was avoided by adding 2 wt% B2O3. The optimal flux concentration for the YBaCuFeO5 growth can be extracted to be near YBaCuFeO5:CuO=13:87 in molar ratio. The crystal quality was confirmed by the satisfactory refinement of crystal structure of space group P4mm and the two consecutive anisotropic antiferromagnetic phase transitions near 455 K and 170 K.

[Heavy metal concentration in Nanjing urban soils and their affecting factors].

PubMed

Lu, Ying; Gong, Zitong; Zhang, Ganlin; Zhang, Bo

2004-01-01

The concentration and source of heavy metals in Nanjing urban soils and their relationships with soil properties were studied. The results indicated that the soils in Nanjing urban were not obviously polluted by Fe, Ni, Co and V, but polluted by Mn, Cr, Cu, Zn, and Pb to a certain extent. The heavy metals were irregularly distributed in soil profiles. Fe, Ni, Co, and V were originated from soil materials, but Cu, Zn, Pb, and Cr were anthropogenic input. Probably, Mn had different origins in different soils. There were positive correlations among Fe, Cr, Ni, Co, and V concentration, and among Cu, Zn, Pb, and Cr concentration. The Fe, Co, V, and Ni concentration were positively correlated with soil clay content and CEC, and the Cu, Zn and Pb concentration were negatively correlated with clay content. There were positive correlations between Cu, Zn, Pb and Cr concentration and organic C content, and between Pb concentration and soil pH.

Antifriction coating of Cu-Fe-Al-Pb system for plain bearings

NASA Astrophysics Data System (ADS)

Kotenkov, Pavel; Kontsevoi, Yurii; Mejlakh, Anna; Pastukhov, Eduard; Shubin, Alexey; Goyda, Eduard; Sipatov, Ivan

2017-09-01

Aluminium, copper and their compounds are used in common as basis for antifriction coatings of plain bearings. Antifriction testing of plain bearings (based on Al and Cu) made by leading automotive manufacturers from Germany, Japan, USA, United Kingdom and Russia were carried out to make judicious selection of basis for development of new antifriction material. Testing was carried out using friction machine. It was defined that materials based on Cu provide better durability and robustness of plain bearings in comparison with Al based ones. The new antifriction composite coatings based on copper were developed taking into account the requirements specified for plain bearings of internal-combustion engine. Pilot samples of plain bearings with antifriction coatings of Cu-Fe-Al-Pb system were produced. The antifriction composite having Cu-5Fe-5Al5Fe2-10Pb (mass %) composition has demonstrated low friction factor and high wear-resistance. Metallographic analysis of pilot samples was carried out by means of optical and scanning electron microscopy.

Structural, magnetic and transport properties of 2D structured perovskite oxychalcogenides

NASA Astrophysics Data System (ADS)

Berthebaud, David; Lebedev, Oleg I.; Pelloquin, Denis; Maignan, Antoine

2014-10-01

We have been looking for new potential thermoelectric materials in the family of 2D structured perovskite oxychalcogenides containing [Cu2Ch2]2- blocks (Ch = S or Se). Using high temperature syntheses, a new oxyselenide Sr2CuFeO3Se has been isolated and its structure has been compared to the isotypes sulfides, Ca2CuFeO3S and Sr2CuFeO3S, prepared by the same technique. By combining powder XRD and TEM analyses their composition and structure were analyzed. They all three crystallize in the Sr2CuGaO3S-type structure, with only the oxyselenide showing a Fe deficiency which is related to the stacking faults evidenced by high resolution TEM. Transport and magnetic properties of the samples have been studied; especially their electrical resistivity is characterized by high values in the range from 1 to 10 kΩ cm at 300 K. Thermoelectric potential of these materials is also discussed.

Fabrication of an Fe80.5Si7.5B6Nb5Cu Amorphous-Nanocrystalline Powder Core with Outstanding Soft Magnetic Properties

NASA Astrophysics Data System (ADS)

Zhang, Zongyang; Liu, Xiansong; Feng, Shuangjiu; Rehman, Khalid Mehmood Ur

2018-03-01

In this study, the melt spinning method was used to develop Fe80.5Si7.5B6Nb5Cu amorphous ribbons in the first step. Then, the Fe80.5Si7.5B6Nb5Cu amorphous-nanocrystalline core with a compact microstructure was obtained by multiple processes. The main properties of the magnetic powder core, such as micromorphology, thermal behavior, permeability, power loss and quality factor, have been analyzed. The obtained results show that an Fe80.5Si7.5B6Nb5Cu amorphous-nanocrystalline duplex core has high permeability (54.8-57), is relatively stable at different frequencies and magnetic fields, and the maximum power loss is only 313 W/kg; furthermore, it has a good quality factor.

Nanostructured iron(III)-copper(II) binary oxide: a novel adsorbent for enhanced arsenic removal from aqueous solutions.

PubMed

Zhang, Gaosheng; Ren, Zongming; Zhang, Xiwang; Chen, Jing

2013-08-01

To obtain a highly efficient and low-cost adsorbent for arsenic removal from water, a novel nanostructured Fe-Cu binary oxide was synthesized via a facile co-precipitation method. Various techniques including BET surface area measurement, powder XRD, SEM, and XPS were used to characterize the synthetic Fe-Cu binary oxide. It showed that the oxide was poorly crystalline, 2-line ferrihydrite-like and was aggregated with many nanosized particles. Laboratory experiments were performed to investigate adsorption kinetics, adsorption isotherms, pH adsorption edge and regeneration of spent adsorbent. The results indicated that the Fe-Cu binary oxide with a Cu: Fe molar ratio of 1:2 had excellent performance in removing both As(V) and As(III) from water, and the maximal adsorption capacities for As(V) and As(III) were 82.7 and 122.3 mg/g at pH 7.0, respectively. The values are favorable, compared to those reported in the literature using other adsorbents. The coexisting sulfate and carbonate had no significant effect on arsenic removal. However, the presence of phosphate obviously inhibited the arsenic removal, especially at high concentrations. Moreover, the Fe-Cu binary oxide could be readily regenerated using NaOH solution and be repeatedly used. The Fe-Cu binary oxide could be a promising adsorbent for both As(V) and As(III) removal because of its excellent performance, facile and low-cost synthesis process, and easy regeneration. Copyright © 2013 Elsevier Ltd. All rights reserved.

Transition metal ion-assisted photochemical generation of alkyl halides and hydrocarbons from carboxylic acids.

PubMed

Carraher, Jack M; Pestovsky, Oleg; Bakac, Andreja

2012-05-21

Near-UV photolysis of aqueous solutions of propionic acid and aqueous Fe(3+) in the absence of oxygen generates a mixture of hydrocarbons (ethane, ethylene and butane), carbon dioxide, and Fe(2+). The reaction becomes mildly catalytic (about five turnovers) in the presence of oxygen which converts a portion of alkyl radicals to oxidizing intermediates that reoxidize Fe(2+). The photochemistry in the presence of halide ions (X(-) = Cl(-), Br(-)) generates ethyl halides via halogen atom abstraction from FeX(n)(3-n) by ethyl radicals. Near-quantitative yields of C(2)H(5)X are obtained at ≥0.05 M X(-). Competition experiments with Co(NH(3))(5)Br(2+) provided kinetic data for the reaction of ethyl radicals with FeCl(2+) (k = (4.0 ± 0.5) × 10(6) M(-1) s(-1)) and with FeBr(2+) (k = (3.0 ± 0.5) × 10(7) M(-1) s(-1)). Photochemical decarboxylation of propionic acid in the presence of Cu(2+) generates ethylene and Cu(+). Longer-chain acids also yield alpha olefins as exclusive products. These reactions become catalytic under constant purge with oxygen which plays a dual role. It reoxidizes Cu(+) to Cu(2+), and removes gaseous olefins to prevent accumulation of Cu(+)(olefin) complexes and depletion of Cu(2+). The results underscore the profound effect that the choice of metal ions, the medium, and reaction conditions exert on the photochemistry of carboxylic acids.

Determination of Microelements in Human Milk and Infant Formula Without Digestion by ICP-OES.

PubMed

Đurović, Dijana; Milisavljević, Branka; Nedović-Vuković, Mirjana; Potkonjak, Branislav; Spasić, Snežana; Vrvić, Miroslav

2017-06-01

The concentrations of zinc (Zn), iron (Fe) and copper (Cu) in both human milk and infant formula were determined using a new sample preparation method, by inductively coupled plasma - optical emission spectometry (ICP-OES) and flame atomic absorption spectrometry (FAAS). Human milk samples were diluted in ultrapure water. The infant formula of powder samples (suitable for an infant 1-6 months of age) and standard reference material (SRM-1849) were analyzed in parallel. The results have shown that FAAS method was more sensitive for Fe determination in human milk while ICP-OES was more sensitive for both Zn and Cu detection. The limit of quantification for both Zn and Cu was 5 μg L-1 and 10 μg L-1 for Fe and the recovery for Zn, Fe and Cu was ranged from 90% to 94%, 97% to 103% and 90% to 102%, respectively. Mean concentrations of Zn, Fe, and Cu in human milk samples were 5.35, 0.47 and 0.83 mg L-1, respectively while these values in infant formula were ranged from 3.52-4.75 mg L-1, 3.37-4.56 mg L-1 and 0.28-0.41 mg L-1, respectively. Despite the sample complexity, the proposed method using dilution of milk samples with water was simple, rapid, effective and accurate. ICP-OES was a better method for Zn determination while FAAS was a better method for Fe determination. In the case of Cu both methods were comparable.

Spectrophotometric and electrochemical study for metal ion binding of azocalix[4]arene bearing p-ethylester group

NASA Astrophysics Data System (ADS)

Kim, Tae Hyun

2017-05-01

The complexation behavior of diazophenylcalix[4]arene bearing para-ethylester group (p-EAC) for alkali, alkaline earth, various heavy and transition metal ions (Li+, Na+, K+, Rb+, Cs+, Mg2 +, Ca2 +, Sr2 +, Ba2 +, Cr3 +, Fe2 +, Co2 +, Ni2 +, Cu2 +, Zn2 +, Pb2 +) was investigated by spectrophotometric and electrochemical methods in CH3CN. p-EAC exhibits decreased absorbance at 353 nm in the presence of Cr3 +, Fe2 +, Pb2 +, and Cu2 +. The spectra of p-EAC showed bathochromic shift in absorption maximum on the addition of Cr3 +, Fe2 +, or Pb2 + with decreasing order of absorbance (Cr3 + > Fe2 + > Pb2 +), and on the other hand, hypsochromic shift on the addition of Cu2 +. This leads to the selective coloration from light green to orange and colorless for Cr3 + and Cu2 + that can be detected by the naked eye, respectively. In electrochemistry experiments, p-EAC also showed two different types of voltammetric changes toward Cr3 +, Fe2 +, or Pb2 +, and toward Cu2 +, whereas no significant changes occurred in the presence of the other metal ions. Nonlinear fitting curve procedure was used to determine a logarithmic value of 5.20, 4.92, 3.54 and 4.80 for the stability constants of the complex of p-EAC with Cr3 +, Fe2 +, Pb2 +, and Cu2 +, respectively.

Fe3O4@mSiO2-FA-CuS-PEG nanocomposites for magnetic resonance imaging and targeted chemo-photothermal synergistic therapy of cancer cells.

PubMed

Gao, Zhifang; Liu, Xijian; Deng, Guoying; Zhou, Feng; Zhang, Lijuan; Wang, Qian; Lu, Jie

2016-09-14

In this work, a new multifunctional nanoplatform (Fe3O4@mSiO2-FA-CuS-PEG nanocomposite) for magnetic resonance imaging (MRI) and targeted chemo-photothermal therapy, was firstly fabricated on the basis of magnetic mesoporous silica nanoparticles (Fe3O4@mSiO2), on which folic acid (FA) was grafted as the targeting reagent, CuS nanocrystals were attached as the photothermal agent, and polyethylene glycol (PEG) was coupled to improve biocompatibility. The characterization results demonstrated that the fabricated Fe3O4@mSiO2-FA-CuS-PEG nanocomposites not only showed strong magnetism and excellent MRI performance, but also had a high doxorubicin (DOX, an anticancer drug) loading capacity (22.1%). The loaded DOX can be sustainably released, which was apt to be controlled by pH adjustment and near infrared (NIR) laser irradiation. More importantly, targeted delivery of the DOX-loaded Fe3O4@mSiO2-FA-CuS-PEG nanocomposites could be accomplished in HeLa cells via the receptor-mediated endocytosis pathway, and this exhibited synergistic effect of chemotherapy and photothermal therapy against HeLa cells under irradiation with a 915 nm laser. Therefore, the fabricated multifunctional Fe3O4@mSiO2-FA-CuS-PEG nanocomposite has a great potential in image-guided therapy of cancers.

Simple electrodepositing of CoFe/Cu multilayers: Effect of ferromagnetic layer thicknesses

NASA Astrophysics Data System (ADS)

Tekgül, Atakan; Alper, Mürsel; Kockar, Hakan

2017-01-01

The CoFe/Cu magnetic multilayers were produced by changing CoFe ferromagnetic layers from 3 nm to 10 nm using electrodeposition. By now, the thinnest Cu (0.5 nm) layer thicknesses were used to see whether the GMR effect in the multilayers can be obtained or not since the pinning of non-magnetic layer between the ferromagnetic layers is required. For the proper depositions, the cyclic voltammograms was used, and the current-time transients were obtained. The Cu and CoFe layers were deposited at a cathode potential of -0.3 and -1.5 V with respect to saturated calomel electrode, respectively. From the XRD patterns, the multilayers were shown to be fcc crystal structures. For the magnetization measurements, saturation magnetization increases from 160 to 600 kA/m from 3 to 8 nm ferromagnetic layer thicknesses. And, the coercivity values increase until the 8 nm of the CoFe layer thickness. It is seen that the thin Cu layer (fixed at 0.5 nm) and pinholes support the random magnetization orientation and thus all multilayers exhibited the giant magnetoresistance (GMR) effect, and the highest GMR value was observed about 5.5%. And, the variation of GMR field sensitivity was calculated. The results show that the GMR and GMR sensitivity are compatible among the multilayers. The CoFe/Cu magnetic multilayers having GMR properties are used in GMR sensors and hard disk drive of the nano-technological devices.

Characterisation of the antiferromagnetic transition of Cu2FeSnS4, the synthetic analogue of stannite

NASA Astrophysics Data System (ADS)

Caneschi, A.; Cipriani, C.; di Benedetto, F.; Sessoli, R.

2003-04-01

Magnetisation measurements between 260 and 1.9K were performed on the synthetic analogue of stannite, Cu_2FeSnS_4, tetragonal Ioverline{4}2m. Fe(II) ions, in the high spin S=2 configuration for tetrahedral coordination, are responsible for the high temperature paramagnetism. In agreement with Bernardini et al. (2000), an antiferromagnetic transition was observed, lowering temperature below 8K. Refined measurements evidenced a T_N=6.1K for the Néel temperature. In spite of a small difference, observed in the behaviour between the zero-field cooled and the field cooled curves, which suggests the possible presence of a spin-glass phase, the AC measurements did not provide evidence of dependence of the magnetic susceptibility on frequency, as expected in spin-glass systems. On the basis of the experimental data, in agreement with the existent literature (Fries et al., 1997), a collinear antiferromagnetic structure should be preferred. The Fe ions, in fact, are distributed in two sublattices obtained by magnetic differentiation of the symmetry equivalent (0,0,0) and (frac{1}{2}frac{1}{2}frac{1}{2}) Fe positions (wyckoff: 2a). The low value for the Nèel temperature, as compared e.g. to the room-temperature antiferromagnet chalcopyrite (CuFeS_2), very close in composition and structure to stannite, is to be related to the increased distance between the Fe ions (˜6.6Å). This weak interaction is not detected in natural samples, where diamagnetic Zn(II) replace paramagnetic Fe(II), thus increasing the mean Fe-Fe distance. Fries, T., Shapira, Y., Palacio, F., Moròn, M.C., McIntyre, G.J., Kershaw, R., Wold, A. and McNiff, E.J. Jr. (1997): Mangetic ordering of the antiferromagnet Cu_2MnSnS_4 from magnetisation and neutron-scattering measurements. Phys. Rev. B, 6(9), 5424-5431 Bernardini, G.P., Borrini, D., Caneschi, A. Di Benedetto, F., Gatteschi, D., Ristori, S. and Romanelli, M. (2000): EPR and SQUID magnetometry study of Cu_2FeSnS_4 (stannite) and Cu_2ZnSnS_4 (kesterite). Phys. Chem. Minerals, 7, 453-461

Improvement in surface conditions of electroplated Fe-Pt thick-film magnets

NASA Astrophysics Data System (ADS)

Yanai, T.; Honda, J.; Hamamura, R.; Omagari, Y.; Yamada, H.; Fujita, N.; Takashima, K.; Nakano, M.; Fukunaga, H.

2018-05-01

Fe-Pt thick-films were electroplated on Ta, Ti, Co, Ni, and Cu plates (substrates) using a direct current, and the surface morphology, the magnetic properties, and the crystal structure of the films were evaluated. The films plated on the Co, Ni, and Cu substrates showed much smooth surface compared with those for the Ta and Ti ones, and we confirmed that the Cu plate was the most attractive substrate due to very small cracks after an annealing for L10 ordering. High coercivity (>800 kA/m) for the Cu substrate is almost the same as that for our previous study in which we employed the Ta substrate, and we found that the Cu plate is a hopeful substrate to improve the surface conditions of electroplated Fe-Pt thick-film magnets.

Effect of Cu-doping on structural and electrical properties of Ni0.4-xCu0.3+xMg0.3Fe2O4 ferrites prepared using sol-gel method

NASA Astrophysics Data System (ADS)

Dhaou, Mohamed Houcine

2018-06-01

Ni0.4-xCu0.3+xMg0.3Fe2O4 spinel ferrites were prepared by sol-gel technique. X-ray diffraction results indicate that ferrite samples have a cubic spinel-type structure with ? space group. The electrical properties of the studied samples using complex impedance spectroscopy technique have been investigated as a function of frequency at different temperatures. We found that the addition of copper in Ni0.4-xCu0.3+xMg0.3Fe2O4 ferrite system can improve its conductivity. Dielectric properties have been discussed in terms of hopping of charge carriers between Fe2+ and Fe3+ ions. For all samples, frequency dependence of the imaginary part of impedance (Z") shows the existence of relaxation phenomenon. The appropriate equivalent circuit configuration for modeling the Nyquist plots of impedance is of the type of (Rg + Rgb//Cgb).

Spin valves with spin-engineered domain-biasing scheme

NASA Astrophysics Data System (ADS)

Lu, Z. Q.; Pan, G.

2003-06-01

Synthetic spin-filter spin valves with spin-engineered biasing scheme "sub/Ta/NiFe/IrMn/NiFe/NOL/Cu1/CoFe/Cu2/CoFe/Ru/CoFe/IrMn/Ta" were developed. In the structure, the orthogonal magnetic configuration for biasing and pinning field was obtained by one-step magnetic annealing process by means of spin flop, which eliminated the need for two antiferromagnetic materials with distinctively different blocking temperatures and two-step magnetic annealing as in conventional exchange biasing scheme. The longitudinal domain biasing of spin valves was achieved by using interlayer coupling field through Cu1 spacer. By adjusting the thickness of the Cu1 layer, the interlayer coupling biasing field can provide domain stabilization and was sufficiently strong to constrain the magnetization in coherent rotation. This can prevent Barkhausen noises associated with magnetization reversal. We report here a proof of concept study of such a domain-biasing scheme, which has its important technological applications in nanoscale spin valve and magnetic tunneling junction read heads and other spintronic devices.

Coercivity enhancement in hot deformed Nd2Fe14B-type magnets by doping low-melting RCu alloys (R = Nd, Dy, Nd + Dy)

NASA Astrophysics Data System (ADS)

Lee, Y. I.; Huang, G. Y.; Shih, C. W.; Chang, W. C.; Chang, H. W.; You, J. S.

2017-10-01

Magnetic properties of the anisotropic NdFeB magnets prepared by hot pressing followed by die-upsetting NdFeB MQU-F powders doped with low-melting RCu alloy powders were explored, where RCu stands for Nd70Cu30, Dy70Cu30 and (Nd0.5Dy0.5)70Cu30, respectively. In addition, the post-annealing at 600 °C was employed to modify the microstructures and the magnetic properties of the hot deformed magnets. It is found that doping RCu alloy powders is effective in enhancing the coercivity of the hot deformed NdFeB magnets from 15.1 kOe to 16.3-19.5 kOe. For Nd70Cu30-doped magnets, the increment of coercivity is only 1.2 kOe. Meanwhile, Dy70Cu30-doped and (Nd0.5Dy0.5)70Cu30-doped magnets show an almost identical enhancement of coercivity of about 4.4 kOe. Importantly, the latter magnet shows a beneficial effect of reducing the usage of Dy from 1.6 wt% to 0.8 wt%. TEM analysis shows that nonmagnetic Nd, Dy and Cu appear at grain boundary and isolate the magnetic grains, leading to an enhancement of coercivity. Doping lower melting point Dy-lean (Nd0.5Dy0.5)70Cu30 powders into commercial MQU-F powders for making high coercivity hot deformed NdFeB magnets might be a potential and economic way for mass production.

Understanding Cu release into environment from Kure massive sulfide ore deposits, Kastamonu, NW Turkey

NASA Astrophysics Data System (ADS)

Demirel, Cansu; Sonmez, Seref; Balci, Nurgul

2014-05-01

Covering a wide range on the earth's crust, oxidation of metal sulfide minerals have vital environmental impacts on the aquatic environment, causing one of the major environmental problems known as acid mine drainage (AMD). Located in the Kastamonu province of the Western Black Sea region, Kure district is one of the major copper mining sites in Turkey. Mining activities in the area heads back to ancient times, such that operation is thought to be started with the Roman Empire. Currently, only the underground mining tunnels of Bakibaba and Asikoy are being operated. Thus, mining heaps and ores of those pyritic deposits have been exposed to the oxidative conditions for so long. As a result of weathering processes of past and recent heaps of the Kure volcanic massive sulfide deposits in addition to the main ore mineral (chalcopyrite), significant amount of metals, especially Cu, are being released into the environment creating undesirable environmental conditions. In order to elucidate Cu release mechanisms from Kure pyritic ore deposits and mining wastes, field and laboratory approaches were used. Surface water and sediment samples from the streams around the mining and waste sites were collected. Groundwater samples from the active underground mining site were also collected. Physical parameters (pH, Eh, T°C, and EC) of water samples were determined in situ and in the laboratory using probes (WTW pH 3110, WTW Multi 9310 and CRISON CM 35). Metal and ion concentrations of the water samples were analysed using ICP-MS and DR 2800 spectrophotometer, respectively. High Cu, Co, Zn and Fe concentrations were determined in the water samples with pH values ranging from 2.9- 4. Cu concentrions ranges from 345 ppm to 36 ppm in the water samples. Consistent with the water samples, high Cu, Fe, Zn and Co were also determined in the sediment samples. Laboratory chalcopyrite oxidation experiments under the conditions representing the field site were set up as biological and abiotic in order to elucidate Cu release from ore and wastes. Greater Cu release were measured from the biological experiments carried out with S and Fe oxidizers compared to those from the chemical experiments. Fe-oxide precipitation experiments carried out in the laboratory showed high Cu absorbtion into Fe-oxides produced by biological reactions carried out with Fe oxidizers. Overall, these preliminary experimental results showed that Cu release and migration from the source can be controlled by various microorganims which regulate S and Fe cycles in the field. Key words: Metal sulfide oxidation, Kure pyritic copper mines, AMD, Bioleaching, Secondary Fe-oxide precipitation

Shock synthesis of quasicrystals with implications for their origin in asteroid collisions

DOE PAGES

Asimow, Paul D.; Lin, Chaney; Bindi, Luca; ...

2016-06-28

Here, we designed a plate impact shock recovery experiment to simulate the starting materials and shock conditions associated with the only known natural quasicrystals, in the Khatyrka meteorite. At the boundaries among CuAl5, (Mg 0.75Fe 0.25 2+) 2SiO 4 olivine, and the stainless steel chamber walls, the recovered specimen contains numerous micron-scale grains of a quasicrystalline phase displaying face-centered icosahedral symmetry and low phason strain. The compositional range of the icosahedral phase is Al 68-73Fe 11-16Cu 10-12Cr 1-4Ni 1-2 and extends toward higher Al/(Cu+Fe) and Fe/Cu ratios than those reported for natural icosahedrite or for any previously known synthetic quasicrystalmore » in the Al-Cu-Fe system. The shock-induced synthesis demonstrated in this experiment reinforces the evidence that natural quasicrystals formed during a shock event but leaves open the question of whether this synthesis pathway is attributable to the expanded thermodynamic stability range of the quasicrystalline phase at high pressure, to a favorable kinetic pathway that exists under shock conditions, or to both thermodynamic and kinetic factors.« less

Shock synthesis of quasicrystals with implications for their origin in asteroid collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asimow, Paul D.; Lin, Chaney; Bindi, Luca

Here, we designed a plate impact shock recovery experiment to simulate the starting materials and shock conditions associated with the only known natural quasicrystals, in the Khatyrka meteorite. At the boundaries among CuAl5, (Mg 0.75Fe 0.25 2+) 2SiO 4 olivine, and the stainless steel chamber walls, the recovered specimen contains numerous micron-scale grains of a quasicrystalline phase displaying face-centered icosahedral symmetry and low phason strain. The compositional range of the icosahedral phase is Al 68-73Fe 11-16Cu 10-12Cr 1-4Ni 1-2 and extends toward higher Al/(Cu+Fe) and Fe/Cu ratios than those reported for natural icosahedrite or for any previously known synthetic quasicrystalmore » in the Al-Cu-Fe system. The shock-induced synthesis demonstrated in this experiment reinforces the evidence that natural quasicrystals formed during a shock event but leaves open the question of whether this synthesis pathway is attributable to the expanded thermodynamic stability range of the quasicrystalline phase at high pressure, to a favorable kinetic pathway that exists under shock conditions, or to both thermodynamic and kinetic factors.« less

Metallic ions catalysis for improving bioleaching yield of Zn and Mn from spent Zn-Mn batteries at high pulp density of 10.

PubMed

Niu, Zhirui; Huang, Qifei; Wang, Jia; Yang, Yiran; Xin, Baoping; Chen, Shi

2015-11-15

Bioleaching of spent batteries was often conducted at pulp density of 1.0% or lower. In this work, metallic ions catalytic bioleaching was used for release Zn and Mn from spent ZMBs at 10% of pulp density. The results showed only Cu(2+) improved mobilization of Zn and Mn from the spent batteries among tested four metallic ions. When Cu(2+) content increased from 0 to 0.8 g/L, the maximum release efficiency elevated from 47.7% to 62.5% for Zn and from 30.9% to 62.4% for Mn, respectively. The Cu(2+) catalysis boosted bioleaching of resistant hetaerolite through forming a possible intermediate CuMn2O4 which was subject to be attacked by Fe(3+) based on a cycle of Fe(3+)/Fe(2+). However, poor growth of cells, formation of KFe3(SO4)2(OH)6 and its possible blockage between cells and energy matters destroyed the cycle of Fe(3+)/Fe(2+), stopping bioleaching of hetaerolite. The chemical reaction controlled model fitted best for describing Cu(2+) catalytic bioleaching of spent ZMBs. Copyright © 2015 Elsevier B.V. All rights reserved.

Laser induced surface structuring of Cu for enhancement of field emission properties

NASA Astrophysics Data System (ADS)

Akram, Mahreen; Bashir, Shazia; Jalil, Sohail Abdul; Shahid Rafique, Muhammad; Hayat, Asma; Mahmood, Khaliq

2018-02-01

The effect of Nd:YAG (1064 nm, 10 ns, 10 Hz) laser induced surface structuring of copper (Cu) for enhancement of field emission (FE) properties has been investigated. X-ray diffraction analysis was employed to investigate the surface structural and compositional modifications. The surface structuring was explored by scanning electron microscope investigation. FE properties were studied under UHV conditions in a parallel plate configuration of planar un-irradiated Cu anode and laser irradiated Cu cathode. The Fowler-Nordheim plots were drawn to confirm the dominance of FE behavior of the measured I-V characteristics. The obtained values of turn-on field ‘E o’, field enhancement factor ‘β’ and maximum current density ‘J max’ come out to be to be in the range of 5.5-8.5 V μm-1, 1380-2730 and 147-375 μA cm-2 respectively for the Cu samples irradiated at laser irradiance ranging from 13 to 50 GW cm-2. The observed enhancement in the FE properties has been correlated with the growth of various surface structures such as ridged protrusions, cones and pores/tiny holes. The porous morphology is found to be responsible for a significant enhancement in the FE parameters.

Iron metal production in silicate melts through the direct reduction of Fe/II/ by Ti/III/, Cr/II/, and Eu/II/. [in lunar basalts

NASA Technical Reports Server (NTRS)

Schreiber, H. D.; Balazs, G. B.; Shaffer, A. P.; Jamison, P. L.

1982-01-01

The production of metallic iron in silicate melts by chemical reactions of Ti(3+), Cr(2+), and Eu(2+) with Fe(2+) is demonstrated under experimental conditions in a simplified basaltic liquid. These reactions form a basis for interpreting the role of isochemical valency exchange models in explanations for the reduced nature of lunar basalts. The redox couples are individually investigated in the silicate melt to ascertain reference redox ratios that are independent of mutual interactions. These studies also provide calibrations of spectral absorptions of the Fe(2+) and Ti(2+) species in these glasses. Subsequent spectrophotometric analyses of Fe(2+) and Ti(2+) in glasses doped with both iron and titanium and of Fe(2+) in glasses doped with either iron and chromium or iron and europium ascertain the degree of mutual interactions in these dual-doped glasses.

CuCrZr alloy microstructure and mechanical properties after hot isostatic pressing bonding cycles

NASA Astrophysics Data System (ADS)

Frayssines, P.-E.; Gentzbittel, J.-M.; Guilloud, A.; Bucci, P.; Soreau, T.; Francois, N.; Primaux, F.; Heikkinen, S.; Zacchia, F.; Eaton, R.; Barabash, V.; Mitteau, R.

2014-04-01

ITER first wall (FW) panels are a layered structure made of the three following materials: 316L(N) austenitic stainless steel, CuCrZr alloy and beryllium. Two hot isostatic pressing (HIP) cycles are included in the reference fabrication route to bond these materials together for the normal heat flux design supplied by the European Union (EU). This reference fabrication route ensures sufficiently good mechanical properties for the materials and joints, which fulfil the ITER mechanical specifications, but often results in a coarse grain size for the CuCrZr alloy, which is not favourable, especially, for the thermal creep properties of the FW panels. To limit the abnormal grain growth of CuCrZr and make the ITER FW fabrication route more reliable, a study began in 2010 in the EU in the frame of an ITER task agreement. Two material fabrication approaches have been investigated. The first one was dedicated to the fabrication of solid CuCrZr alloy in close collaboration with an industrial copper alloys manufacturer. The second approach investigated was the manufacturing of CuCrZr alloy using the powder metallurgy (PM) route and HIP consolidation. This paper presents the main mechanical and microstructural results associated with the two CuCrZr approaches mentioned above. The mechanical properties of solid CuCrZr, PM CuCrZr and joints (solid CuCrZr/solid CuCrZr and solid CuCrZr/316L(N) and PM CuCrZr/316L(N)) are also presented.

Mixed-Spin Diamond Chain Cu2FePO4F4(H2O)4 with a Noncollinear Spin Order and Possible Successive Phase Transitions.

PubMed

Lu, Hongcheng; Hayashi, Naoaki; Matsumoto, Yuki; Takatsu, Hiroshi; Kageyama, Hiroshi

2017-08-07

A diamond spin chain system, one of the one-dimensional frustrated lattices, is known to exhibit novel properties, but experimental studies have been exclusively confined to materials with a single spin component. Here, we report on the synthesis, structure, and magnetic properties of a new diamond chain compound Cu 2 FePO 4 F 4 (H 2 O) 4 1 composed of mixed-spins of Cu 2+ (S = 1/2 × 2) and Fe 3+ (S = 5/2). Compound 1 crystallizes in the space group C2/c of the monoclinic crystal system with a = 7.7546(4) Å, b = 12.1290(6) Å, c = 9.9209(6) Å, β = 105.29(1)°, and Z = 4. DC magnetization, Mössbauer spectroscopy, and heat capacity measurements revealed an antiferromagnetic order at 11.3 K with a small ferromagnetic component. It is suggested that ferrimagnetic diamond chains are arranged in an antiferromagnetic fashion (i.e., [...Fe(↑)-2Cu(↓↓)-Fe(↑)...] and [...Fe(↓)-2Cu(↑↑)-Fe(↓)...]) within the ab plane to cancel net magnetization, and the spin orientation of the diamond chains changes alternately along the c axis due to the magnetic anisotropy, leading to a noncollinear spin order. Furthermore, another anomaly is observed in the heat capacity at around 3 K, suggesting a successive magnetic transition or crossover due to competing magnetic interactions.

Effect of Lupinus albus L. root activities on As and Cu mobility after addition of iron-based soil amendments.

PubMed

Fresno, Teresa; Peñalosa, Jesús M; Santner, Jakob; Puschenreiter, Markus; Moreno-Jiménez, Eduardo

2017-09-01

Arsenic and Cu mobility was investigated in the rhizosphere of Lupinus albus L. grown in an iron-amended contaminated soil. White lupin was grown in rhizobags in contaminated soil either left untreated or amended with iron sulphate plus lime (Fe + lime) or biochar (Fe + BC). Porewater was monitored in rhizosphere and bulk soil throughout the experiment and the extractable fraction of several elements and As and Cu plant uptake was analysed after 48 days. The distribution of As, Cu, P and Fe in the lupin rhizosphere was evaluated with chemical images obtained by laser ablation-ICP-MS analysis of diffusive gradients in thin films (DGT) gels. The treatments effectively reduced the soluble and extractable As and Cu fractions in the bulk soil, but they did not affect plant uptake. In all cases, soluble As was slightly enhanced in the rhizosphere. This difference was more pronounced in the Fe + lime-treated rhizosphere soil, where an increase of pH as well as extractable As and Fe concentrations were also observed. Chemical imaging of the lupin rhizosphere also showed slightly higher As- and Fe-DGT fluxes around lupin roots grown in the non-amended soil. Our findings indicate As and Fe co-solubilisation by lupin root exudates, likely as a response to P deficiency. Arsenic mobilisation occurred only in the rhizosphere and was not decreased by the amendments. Copyright © 2017 Elsevier Ltd. All rights reserved.

A perovskite oxide with high conductivities in both air and reducing atmosphere for use as electrode for solid oxide fuel cells.

PubMed

Lan, Rong; Cowin, Peter I; Sengodan, Sivaprakash; Tao, Shanwen

2016-08-22

Electrode materials which exhibit high conductivities in both oxidising and reducing atmospheres are in high demand for solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOECs). In this paper, we investigated Cu-doped SrFe0.9Nb0.1O3-δ finding that the primitive perovskite oxide SrFe0.8Cu0.1Nb0.1O3-δ (SFCN) exhibits a conductivity of 63 Scm(-1)and 60 Scm(-1) at 415 °C in air and 5%H2/Ar respectively. It is believed that the high conductivity in 5%H2/Ar is related to the exsolved Fe (or FeCu alloy) on exposure to a reducing atmosphere. To the best of our knowledge, the conductivity of SrFe0.8Cu0.1Nb0.1O3-δ in a reducing atmosphere is the highest of all reported oxides which also exhibit a high conductivity in air. Fuel cell performance using SrFe0.8Cu0.1Nb0.1O3-δ as the anode, (Y2O3)0.08(ZrO2)0.92 as the electrolyte and La0.8Sr0.2FeO3-δ as the cathode achieved a power density of 423 mWcm(-2) at 700 °C indicating that SFCN is a promising anode for SOFCs.

A perovskite oxide with high conductivities in both air and reducing atmosphere for use as electrode for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Lan, Rong; Cowin, Peter I.; Sengodan, Sivaprakash; Tao, Shanwen

2016-08-01

Electrode materials which exhibit high conductivities in both oxidising and reducing atmospheres are in high demand for solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOECs). In this paper, we investigated Cu-doped SrFe0.9Nb0.1O3-δ finding that the primitive perovskite oxide SrFe0.8Cu0.1Nb0.1O3-δ (SFCN) exhibits a conductivity of 63 Scm-1and 60 Scm-1 at 415 °C in air and 5%H2/Ar respectively. It is believed that the high conductivity in 5%H2/Ar is related to the exsolved Fe (or FeCu alloy) on exposure to a reducing atmosphere. To the best of our knowledge, the conductivity of SrFe0.8Cu0.1Nb0.1O3-δ in a reducing atmosphere is the highest of all reported oxides which also exhibit a high conductivity in air. Fuel cell performance using SrFe0.8Cu0.1Nb0.1O3-δ as the anode, (Y2O3)0.08(ZrO2)0.92 as the electrolyte and La0.8Sr0.2FeO3-δ as the cathode achieved a power density of 423 mWcm-2 at 700 °C indicating that SFCN is a promising anode for SOFCs.

A perovskite oxide with high conductivities in both air and reducing atmosphere for use as electrode for solid oxide fuel cells

PubMed Central

Lan, Rong; Cowin, Peter I.; Sengodan, Sivaprakash; Tao, Shanwen

2016-01-01

Electrode materials which exhibit high conductivities in both oxidising and reducing atmospheres are in high demand for solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOECs). In this paper, we investigated Cu-doped SrFe0.9Nb0.1O3−δ finding that the primitive perovskite oxide SrFe0.8Cu0.1Nb0.1O3−δ (SFCN) exhibits a conductivity of 63 Scm−1and 60 Scm−1 at 415 °C in air and 5%H2/Ar respectively. It is believed that the high conductivity in 5%H2/Ar is related to the exsolved Fe (or FeCu alloy) on exposure to a reducing atmosphere. To the best of our knowledge, the conductivity of SrFe0.8Cu0.1Nb0.1O3−δ in a reducing atmosphere is the highest of all reported oxides which also exhibit a high conductivity in air. Fuel cell performance using SrFe0.8Cu0.1Nb0.1O3−δ as the anode, (Y2O3)0.08(ZrO2)0.92 as the electrolyte and La0.8Sr0.2FeO3−δ as the cathode achieved a power density of 423 mWcm−2 at 700 °C indicating that SFCN is a promising anode for SOFCs. PMID:27545200

Crystal growth and physical properties of SrCu2As2, SrCu2Sb2, and BaCu2Sb2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anand, V.K.; Perera, P. Kanchana; Pandey, Abhishek

2012-06-25

We report the growth of single crystals of SrCu2As2, SrCu2Sb2, SrCu2(As0.84Sb0.16)2, and BaCu2Sb2 using the self-flux technique and their structural, magnetic, thermal, and transport properties that were investigated by powder x-ray diffraction (XRD), magnetic susceptibility χ, specific heat Cp, and electrical resistivity ρ measurements versus temperature T from 1.8 to 350 K. Rietveld refinements of XRD patterns for crushed crystals confirm that SrCu2As2 crystallizes in the ThCr2Si2-type body-centered tetragonal structure (space group I4/mmm) and SrCu2Sb2 crystallizes in the CaBe2Ge2-type primitive tetragonal structure (space group P4/nmm). However, as reported previously, BaCu2Sb2 is found to have a large unit cell consisting ofmore » three blocks. Here a ThCr2Si2-type block is sandwiched between two CaBe2Ge2-type blocks along the c axis with an overall symmetry of I4/mmm, as reported, but likely with a monoclinic distortion. The χ data of all these compounds are diamagnetic and reveal nearly T-independent anisotropic behavior. The χ of SrCu2As2 is found to be larger in the ab plane than along the c axis, as also previously reported for pure and doped BaFe2As2, whereas the χ values of SrCu2Sb2 and BaCu2Sb2 are larger along the c axis. This difference in anisotropy appears to arise from the differences between the crystal structures. The finite values of the Sommerfeld linear specific heat coefficients γ and the T dependences of ρ reveal metallic character of all four compounds. The electronic and magnetic properties indicate that these compounds are sp metals with Cu in the nonmagnetic 3d10 electronic configuration corresponding to the oxidation state Cu+1, as previously predicted theoretically for SrCu2As2 by Singh [ Phys. Rev. B 79 153102 (2009)]. We present a brief review of theoretical and experimental work on the doping character of transition metals for Fe in BaFe2As2. The As–As covalent interlayer bond distances in the collapsed-tetragonal (Ca,Sr,Ba)Cu2As2 compounds are much shorter than the nonbonding As–As distances in BaFe2As2. Thus, the electronic character of the Cu and the strength of the As–As interlayer bonding are both expected to drastically change between weakly Cu-substituted BaFe2As2 and pure BaCu2As2, perhaps via a first-order lattice instability such as a miscibility gap in the Ba(Fe1−xCux)2As2 system.« less

The origin and evolution of r- and s-process elements in the Milky Way stellar disk

NASA Astrophysics Data System (ADS)

Battistini, Chiara; Bensby, Thomas

2016-02-01

Context. Elements heavier than iron are produced through neutron-capture processes in the different phases of stellar evolution. Asymptotic giant branch (AGB) stars are believed to be mainly responsible for elements that form through the slow neutron-capture process, while the elements created in the rapid neutron-capture process have production sites that are less understood. Knowledge of abundance ratios as functions of metallicity can lead to insight into the origin and evolution of our Galaxy and its stellar populations. Aims: We aim to trace the chemical evolution of the neutron-capture elements Sr, Zr, La, Ce, Nd, Sm, and Eu in the Milky Way stellar disk. This will allow us to constrain the formation sites of these elements, as well as to probe the evolution of the Galactic thin and thick disks. Methods: Using spectra of high resolution (42 000 ≲ R ≲ 65 000) and high signal-to-noise (S/N ≳ 200) obtained with the MIKE and the FEROS spectrographs, we determine Sr, Zr, La, Ce, Nd, Sm, and Eu abundances for a sample of 593 F and G dwarf stars in the solar neighborhood. The abundance analysis is based on spectral synthesis using one-dimensional, plane-parallel, local thermodynamic equilibrium (LTE) model stellar atmospheres calculated with the MARCS 2012 code. Results: We present abundance results for Sr (156 stars), Zr (311 stars), La (242 stars), Ce (365 stars), Nd (395 stars), Sm (280 stars), and Eu (378 stars). We find that Nd, Sm, and Eu show trends similar to what is observed for the α elements in the [X/Fe]-[Fe/H] abundance plane. For [Sr/Fe] and [Zr/Fe], we find decreasing abundance ratios for increasing metallicity, reaching sub-solar values at super-solar metallicities. [La/Fe] and [Ce/Fe] do not show any clear trend with metallicity, and they are close to solar values at all [Fe/H]. The trends of abundance ratios [X/Fe] as a function of stellar ages present different slopes before and after 8 Gyr. Conclusions: The rapid neutron-capture process is active early in the Galaxy, mainly in type-II supernovae from stars in the mass range 8-10 M⊙. Europium is almost completely produced by the r-process, but Nd and Sm show similar trends to Eu even if their s-process component is higher. Strontium and Zr are thought to be mainly produced by the s-process, but show significant enrichment at low metallicity that requires extra r-process production, which probably is different from the classical r-process. Finally, La and Ce are mainly produced via s-process from AGB stars in the mass range 2-4 M⊙, which can be seen by the decrease in [La/Eu] and [Ce/Eu] at [Fe/H] ≈ -0.5. The trend of [X/Fe] with age could be explained by considering that the decrease in [X/Fe] for the thick disk stars can be due to the decrease in type-II supernovae with time, meaning a reduced enrichment of r-process elements in the interstellar medium. In the thin disk, the trends are flatter, which is probably due to the main production from the s-process being balanced by Fe production from type-Ia supernovae. This paper includes data gathered with the 6.5 m Magellan Telescopes at the Las Campanas Observatory, Chile and the ESO 1.5-m, 2.2-m. and 3.6-m telescopes on La Silla, Chile (ESO Proposal ID 65.L-0019, 67.B-0108, 76.B-0416, 82.B-0610); and data from UVES Paranal Observatory Project (ESO DDT Program ID 266.D-5655).Full Tables 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A49

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolesnikov, S. V., E-mail: kolesnikov@physics.msu.ru; Klavsyuk, A. L.; Saletsky, A. M.

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.

Reduction of Ag{sup I}, Au{sup III}, Cu{sup II}, and Hg{sup II} by Fe{sup II}/Fe{sup III} hydroxysulfate green rust.

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Loughlin, E. J.; Kelly, S. D.; Kemner, K. M.

Green rusts are mixed Fe{sup II}/Fe{sup III} hydroxides that are found in many suboxic environments where they are believed to play a central role in the biogeochemical cycling of iron. X-ray absorption fine structure analysis of hydroxysulfate green rust suspensions spiked with aqueous solutions of AgCH{sub 3}COO, AuCl{sub n}(OH){sub 4-n}, CuCl{sub 2}, or HgCl{sub 2} showed that Ag{sup I}, Au{sup III}, Cu{sup II}, and Hg{sup II} were readily reduced to Ag{sup 0}, Au{sup 0}, Cu{sup 0}, and Hg{sup 0}. Imaging of the resulting solids from the Ag{sup I}-, Au{sup III}-, and Cu{sup II}-amended green rust suspensions by transmission electron microscopymore » indicated the formation of submicron-sized particles of Ag{sup 0}, Au{sup 0}, and Cu{sup 0}. The facile reduction of Ag{sup I}, Au{sup III}, Cu{sup II}, and Hg{sup II} to Ag{sup 0}, Au{sup 0}, Cu{sup 0}, and Hg{sup 0}, respectively, by green rust suggests that the presence of green rusts in suboxic soils and sediments can have a significant impact on the biogeochemistry of silver, gold, copper, and mercury, particularly with respect to their mobility.« less

Drastic influence of minor Fe or Co additions on the glass forming ability, martensitic transformations and mechanical properties of shape memory Zr-Cu-Al bulk metallic glass composites.

PubMed

González, Sergio; Pérez, Pablo; Rossinyol, Emma; Suriñach, Santiago; Dolors Baró, Maria; Pellicer, Eva; Sort, Jordi

2014-06-01

The microstructure and mechanical properties of Zr 48 Cu 48 -  x Al 4 M x (M ≡ Fe or Co, x  = 0, 0.5, 1 at.%) metallic glass (MG) composites are highly dependent on the amount of Fe or Co added as microalloying elements in the parent Zr 48 Cu 48 Al 4 material. Addition of Fe and Co promotes the transformation from austenite to martensite during the course of nanoindentation or compression experiments, resulting in an enhancement of plasticity. However, the presence of Fe or Co also reduces the glass forming ability, ultimately causing a worsening of the mechanical properties. Owing to the interplay between these two effects, the compressive plasticity for alloys with x  = 0.5 (5.5% in Zr 48 Cu 47.5 Al 4 Co 0.5 and 6.2% in Zr 48 Cu 47.5 Al 4 Fe 0.5 ) is considerably larger than for Zr 48 Cu 48 Al 4 or the alloys with x  = 1. Slight variations in the Young's modulus (around 5-10%) and significant changes in the yield stress (up to 25%) are also observed depending on the composition. The different microstructural factors that have an influence on the mechanical behavior of these composites are investigated in detail: (i) co-existence of amorphous and crystalline phases in the as-cast state, (ii) nature of the crystalline phases (austenite versus martensite content), and (iii) propensity for the austenite to undergo a mechanically-driven martensitic transformation during plastic deformation. Evidence for intragranular nanotwins likely generated in the course of the austenite-martensite transformation is provided by transmission electron microscopy. Our results reveal that fine-tuning of the composition of the Zr-Cu-Al-(Fe,Co) system is crucial in order to optimize the mechanical performance of these bulk MG composites, to make them suitable materials for structural applications.

Drastic influence of minor Fe or Co additions on the glass forming ability, martensitic transformations and mechanical properties of shape memory Zr-Cu-Al bulk metallic glass composites

NASA Astrophysics Data System (ADS)

González, Sergio; Pérez, Pablo; Rossinyol, Emma; Suriñach, Santiago; Baró, Maria Dolors; Pellicer, Eva; Sort, Jordi

2014-06-01

The microstructure and mechanical properties of Zr48Cu48 - x Al4M x (M ≡ Fe or Co, x = 0, 0.5, 1 at.%) metallic glass (MG) composites are highly dependent on the amount of Fe or Co added as microalloying elements in the parent Zr48Cu48Al4 material. Addition of Fe and Co promotes the transformation from austenite to martensite during the course of nanoindentation or compression experiments, resulting in an enhancement of plasticity. However, the presence of Fe or Co also reduces the glass forming ability, ultimately causing a worsening of the mechanical properties. Owing to the interplay between these two effects, the compressive plasticity for alloys with x = 0.5 (5.5% in Zr48Cu47.5Al4Co0.5 and 6.2% in Zr48Cu47.5Al4Fe0.5) is considerably larger than for Zr48Cu48Al4 or the alloys with x = 1. Slight variations in the Young’s modulus (around 5-10%) and significant changes in the yield stress (up to 25%) are also observed depending on the composition. The different microstructural factors that have an influence on the mechanical behavior of these composites are investigated in detail: (i) co-existence of amorphous and crystalline phases in the as-cast state, (ii) nature of the crystalline phases (austenite versus martensite content), and (iii) propensity for the austenite to undergo a mechanically-driven martensitic transformation during plastic deformation. Evidence for intragranular nanotwins likely generated in the course of the austenite-martensite transformation is provided by transmission electron microscopy. Our results reveal that fine-tuning of the composition of the Zr-Cu-Al-(Fe,Co) system is crucial in order to optimize the mechanical performance of these bulk MG composites, to make them suitable materials for structural applications.

Characterization of copper oxides, iron oxides, and zinc copper ferrite desulfurization sorbents by X-ray photoelectron spectroscopy and scanning electron microscopy

NASA Astrophysics Data System (ADS)

Siriwardane, Ranjani V.; Poston, James A.

1993-05-01

Characterization of copper oxides, iron oxides, and zinc copper ferrite desulfurization sorbents was performed by X-ray photoelectron spectroscopy and scanning electron microscopy/energy-dispersive spectroscopy at temperatures of 298 to 823 K. Analysis of copper oxides indicated that the satellite structure of the Cu22p region was absent in the Cu(I) state but was present in the Cu(II) state. Reduction of CuO at room temperature was observed when the ion gauge was placed close to the sample. The satellite structure was absent in all the copper oxides at 823 K in vacuum. Differentiation of the oxidation state of copper utilizing both Cu(L 3M 4,5M 4,5) X-ray-induced Auger lines and Cu2p satellite structure, indicated that the copper in zinc copper ferrite was in the + 1 oxidation state at 823 K. This + 1 state of copper was not significantly changed after exposure to H 2, CO, and H 2O. There was an increase in Cu/Zn ratio and a decrease in Fe/Zn ratio on the surface of zinc copper ferrite at 823 K compared to that at room temperature. These conditions of copper offered the best sulfidation equilibrium for the zinc copper ferrite desulfurization sorbent. Analysis of iron oxides indicated that there was some reduction of both Fe 2O 3 and FeO at 823K. The iron in zinc copper ferrite was similar to that of Fe 2O 3 at room temperature but there was some reduction of this Fe(III) state to Fe(II) at 823 K. This reduction was more enhanced in the presence of H 2 and CO. Reduction to Fe(II) may not be desirable for the lifetime of the sorbent.

Microstructural Modification of Sn-0.7Cu Solder Alloys by Fe/Bi-Addition for Achieving High Mechanical Performance

NASA Astrophysics Data System (ADS)

Ali, Bakhtiar; Sabri, Mohd Faizul Mohd; Said, Suhana Mohd; Mahdavifard, Mohammad Hossein; Sukiman, Nazatul Liana; Jauhari, Iswadi

2017-08-01

In this work, we studied the Fe/Bi-bearing tin-copper (Sn-0.7Cu) solders for their microstructural and mechanical properties. The microstructure was studied using field emission scanning electron microscopy (FESEM) with a backscattered electron (BSE) detector, x-ray diffraction (XRD) analysis, and energy-dispersive x-ray spectroscopy (EDX). The microstructure study showed that Fe forms very few FeSn2 intermetallic compounds (IMCs) and does not significantly alter the microstructure of Sn-0.7Cu, whereas Bi controls the size of inter-dendritic regions containing Cu6Sn5 and Ag3Sn IMCs of the alloy, as well as significantly refines its primary β-Sn dendrites. Moreover, Bi atoms dissolve in β-Sn matrix, which in turn strengthen the solder by the Bi solid solution strengthening mechanism. Such microstructural modification leads to significant improvements in various mechanical properties of the alloy, including shear strength, impact toughness, and hardness values. Shear tests were performed with a 0.25 mm/min shear speed. The results showed that shear strength improves from 16.57 MPa to 38.36 MPa with the addition of Fe/Bi to Sn-0.7Cu, raising by about 130%. The energy absorbed during impact tests was measured for samples with the help of a Charpy impact testing machine with a 5.4 m/s impact speed. The results revealed that the addition of Fe/Bi to Sn-0.7Cu improves its impact absorbed energy by over 35%, increasing it from 7.5 J to 10.3 J. Vickers hardness tests were carried out for the test samples with a 245.2 mN applied load and 10 s dwell time. The results showed that the hardness number improves from 9.89 to 24.13 with Fe/Bi to Sn-0.7Cu, increasing by about 140%.

Exhibition of veiled features in diffusion bonding of titanium alloy and stainless steel via copper

NASA Astrophysics Data System (ADS)

Thirunavukarasu, Gopinath; Kundu, Sukumar; Laha, Tapas; Roy, Deb; Chatterjee, Subrata

2017-11-01

An investigation was carried out to know the extent of influence of bonding-time on the interface structure and mechanical properties of diffusion bonding (DB) of TiA|Cu|SS. DB of Ti6Al4V (TiA) and 304 stainless steel (SS) using pure copper (Cu) of 200-μm thickness were processed in vacuum using 4-MPa bonding-pressure at 1123 K from 15 to 120 min in steps of 15 min. Preparation of DB was not possible when bonding-time was less than 60 min as the bonding at Cu|SS interface was unsuccessful in spite of effective bonding at TiA|Cu interface; however, successful DB were produced when the bonding-time was 60 min and beyond. DB processed for 60 and 75 min (classified as shorter bonding-time interval) showed distinctive characteristics (structural, mechanical, and fractural) as compared to the DB processed for 90, 105, and 120 min (classified as longer bonding-time interval). DB processed for 60 and 75 min exhibited layer-wise Cu-Ti-based intermetallics at TiA|Cu interface, whereas Cu|SS interface was completely free from reaction products. The layer-wise structure of Cu-Ti-based intermetallics were not observed at TiA|Cu interface in the DB processed for longer bonding-time; however, the Cu|SS interface had layer-wise ternary intermetallic compounds (T1, T2, and T3) of Cu-Fe-Ti-based along with σ phase depending upon the bonding-time chosen. Diffusivity of Ti-atoms in Cu-layer (DTi in Cu-layer) was much greater than the diffusivity of Fe-atoms in Cu-layer (DFe in Cu-layer). Ti-atoms reached Cu|SS interface but Fe-atoms were unable to reach TiA|Cu interface. It was observed that DB fractured at Cu|SS interface when processed for shorter bonding-time interval, whereas the DB processed for longer bonding-time interval fractured apparently at the middle of Cu-foil region predominantly due to the existence of brittle Cu-Fe-Ti-based intermetallics.

Magnetic texturing due to the partial ordering of Fe+3 and Cu+2 in NdBaCuFeO5

NASA Astrophysics Data System (ADS)

Pissas, M.

2017-06-01

The crystal and magnetic structure of the oxygen deficient double perovskite NdBaCuFeO5 was studied, using neutron powder diffraction data. The structure was refined from neutron powder diffraction data using the space groups P 4 / mmm and P 4 mm . For 2K ⩽ T ⩽TN2 = 260K three families of magnetic Bragg peaks exist. These peaks can be indexed with commensurate propagation vectors k1 =[1/2 1/2 1/2], k2 =[1/2 1/2 0] and the incommensurate k3 =[1/2 1/2 0.4]. Above TN2 only magnetic Bragg peaks originated from k1 and k2 propagation, were observed. The incommensurate magnetic structure can be attributed to a circular inclined spiral ordering as in YBaCuFeO5 compound.

Adsorption of tetracycline on Fe (hydr)oxides: effects of pH and metal cation (Cu2+, Zn2+ and Al3+) addition in various molar ratios

PubMed Central

Hsu, Liang-Ching; Liu, Yu-Ting; Syu, Chien-Hui; Huang, Mei-Hsia; Teah, Heng Yi

2018-01-01

Iron (Fe) (hydr)oxides control the mobility and bioavailability of tetracycline (TC) in waters and soils. Adsorption of TC on Fe (hydr)oxides is greatly affected by polyvalent metals; however, impacts of molar metal/TC ratios on TC adsorptive behaviours on Fe (hydr)oxides remain unclear. Results showed that maximum TC adsorption on ferrihydrite and goethite occurred at pH 5–6. Such TC adsorption was generally promoted by the addition of Cu2+, Zn2+ and Al3+. The greatest increase in TC adsorption was found in the system with molar Cu/TC ratio of 3 due to the formation of Fe hydr(oxide)–Cu–TC ternary complexes. Functional groups on TC that were responsible for the complexation with Cu2+shifted from phenolic diketone groups at Cu/TC molar ratio < 1 to amide groups at Cu/TC molar ratio ≥ 1. For the addition of Al3+, the complexation only took place with phenolic diketone groups, resulting in the enhanced TC adsorption at a molar Al/TC ratio of 1. However, TC adsorption decreased for Al/TC molar ratio > 1 as excess Al3+ led to the competitive adsorption with Al/TC complexes. For the Zn2+ addition, no significant correlation was found between TC adsorption capacity and molar Zn/TC ratios. PMID:29657795

Comparison of catalytic activities for photocatalytic and sonocatalytic degradation of organic dye in the presence of ternary Fe{sub 3}O{sub 4}/ZnO/CuO magnetic heteregenous nanocatalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taufik, Ardiansyah; Saleh, Rosari, E-mail: rosari.saleh@gmail.com, E-mail: rosari.saleh@ui.ac.id; Integrated Laboratory of Energy and Environment, Fakultas MIPA-Universitas Indonesia, 16424 Depok

2016-04-19

The Fe{sub 3}O{sub 4}/ZnO/CuO nanocatalyst with various CuO loading were synthesized by sol-gel method and were characterized by powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV-Vis spectroscopy, and vibrating sample magnetometry. The findings demonstrate that all samples exhibit ferromagnetic behavior at room temperatureand containa well-crystalline ternary oxide nanocatalyst. Methylene blue was taken as the model of organic dye to evaluate its photocatalytic and sonocatalytic degradation in the presence of Fe{sub 3}O{sub 4}/ZnO/CuO nanocatalyst. The observed degradation activity indicate that the order of degradation of methylene blue issonocatalysis> photocatalysis. Fe{sub 3}O{sub 4}/ZnO/CuO nanocatalyst with the lowest CuOmore » loading exhibit the highest rate of degradation of methylene blue during the sono- and photocatalytic processes. The experimental data shows that holes are the predominant oxidative species involved in the sono- and photodegradation of methylene blue.« less

Generic NICA-Donnan model parameters for metal-ion binding by humic substances.

PubMed

Milne, Christopher J; Kinniburgh, David G; van Riemsdijk, Willem H; Tipping, Edward

2003-03-01

A total of 171 datasets of literature and experimental data for metal-ion binding by fulvic and humic acids have been digitized and re-analyzed using the NICA-Donnan model. Generic parameter values have been derived that can be used for modeling in the absence of specific metalion binding measurements. These values complement the previously derived generic descriptions of proton binding. For ions where the ranges of pH, concentration, and ionic strength conditions are well covered by the available data,the generic parameters successfully describe the metalion binding behavior across a very wide range of conditions and for different humic and fulvic acids. Where published data for other metal ions are too sparse to constrain the model well, generic parameters have been estimated by interpolating trends observable in the parameter values of the well-defined data. Recommended generic NICA-Donnan model parameters are provided for 23 metal ions (Al, Am, Ba, Ca, Cd, Cm, Co, CrIII, Cu, Dy, Eu, FeII, FeIII, Hg, Mg, Mn, Ni, Pb, Sr, Thv, UVIO2, VIIIO, and Zn) for both fulvic and humic acids. These parameters probably represent the best NICA-Donnan description of metal-ion binding that can be achieved using existing data.

Re-evaluation of the impact of ternary additions of Ni and Cu on the A1 to L1{sub 0} transformation in FePt films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, B.; Barmak, K.

2011-06-15

The impact of ternary additions of Ni (1.6-21.5 at. %) and Cu (1.3-17.3 at. %) on the A1 (face centered cubic, fcc) to L1{sub 0} phase transformation in FePt films has been re-evaluated based on compositions obtained using energy dispersive x-ray spectrometry (EDS). The data presented here serve as corrections to results reported in six previous studies [D. C. Berry and K. Barmak, J. Appl. Phys. 102, 024912 (2007); 101, 014905 (2007); 99, 08G901 (2006); D. C. Berry, J. Kim, K. Barmak, K. Wierman, E. B. Svedberg, and J. K. Howard, Scr. Mater. 53, 423 (2005); K. Barmak, J. Kim,more » D. C. Berry, W. N. Hanani, K. Wierman, E. B. Svedberg, and J. K. Howard, J. Appl. Phys. 97, 024902 (2005); K. Barmak, J. Kim, D. C. Berry, K. W. Wierman, E. B. Svedberg, and J. K. Howard, ibid. 95, 7486 (2004)]. The new EDS compositions do not change the following conclusions of these previous studies: (i) when ternary FeNiPt and FeCuPt alloys are compared with binary FePt alloys with the same Pt content, it is seen that additions of Ni slow the transformation kinetics, whereas additions of Cu have no measurable impact on the kinetics, (ii) the Curie temperature of the L1{sub 0} phase is lowered by additions of Ni or Cu, (iii) the Curie temperature of the A1 phase is increased by additions of Ni, but lowered by additions of Cu, and (iv) the transformation enthalpy is lowered by large additions of Ni, but is unaffected by additions of Cu. The ordering behavior of FeCuPt alloys as evidenced by the kinetic ordering temperature is compared with other reports in the literature based on magnetic measurements.« less

The effect of CuAl addition on the magnetic property, thermal stability and corrosion resistance of the sintered NdFeB magnets

NASA Astrophysics Data System (ADS)

Liu, Y. L.; Liang, J.; He, Y. Ch.; Li, Y. F.; Wang, G. F.; Ma, Q.; Liu, F.; Zhang, Y.; Zhang, X. F.

2018-05-01

To improve the coercivity of the Nd-Fe-B sintered magnets, the Cu29.8Al70.2 (at.%) powders with low melting point were introduced into the Nd-Fe-B magnets. The magnetic properties, microstructure, thermal stability and corrosion behavior of the sintered magnets with different amount of Cu29.8Al70.2 (0,0.25,0.50,0.75,1.0 wt.%) were investigated. When the amount of doped Cu29.8Al70.2 was less than 0.75 wt.%, the coercivity was improved, especially that of the magnets with 0.25 wt.% Cu29.8Al70.2, markedly increased to 13.97 kOe from 12.67 kOe (without CuAl). The improvement of magnetic properties could be attributed to enhanced wettability between Nd2Fe14B phase and Nd-rich phase and decreased exchange coupling between grains, which depended on the optimization of grain boundary microstructure and their distribution by codoping Cu and Al. With the addition of 0-1.0 wt.% Cu29.8Al70.2 powders, the reversible temperature coefficients of remanence and coercivity of the magnets could be also improved. The corrosion resistances was also found to be improved through small addition of Cu29.8Al70.2 powder in 3.5 wt.% NaCl solution by electrochemical and immersion tests, which could be due to the enhancement of the Nd-rich intergranular phase by addition Cu29.8Al70.2.

Major and trace elements in Boletus aereus and Clitopilus prunulus growing on volcanic and sedimentary soils of Sicily (Italy).

PubMed

Alaimo, M G; Dongarrà, G; La Rosa, A; Tamburo, E; Vasquez, G; Varrica, D

2018-08-15

The aim of this study was to determine and compare the content of 28 elements (Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Rb, Sb, Se, Sr, Tl, U, V and Zn) in fruiting bodies of Boletus aereus Bull. and Clitopilus prunulus P. Kumm collected from eleven unpolluted sites of Sicily (Italy) and, also to relate the abundance of chemical elements in soil with their concentration in mushrooms. Median concentrations of the most abundant elements in Boletus aereus ranged from 31,290 μg/g (K) to 107 μg/g (Zn) in caps and from 24,009 μg/g (K) to 57 μg/g (Zn) in stalks with the following abundance order: K > Na > Ca > Mg > Fe > Al > Rb > Zn. The same elements, in the whole fruiting body of Clitopilus prunulus samples, varied in the range 54,073-92 μg/g following the abundance order: K > Na > Mg > Ca > Fe > Al > Rb > Zn. Metal contents in Boletus aereus and in the whole fruiting body of Clitopilus prunulus, collected from the same sampling sites, showed statistically significant differences for most elements. In particular, Clitopilus prunulus contained around two to four times more Co, Cr, Fe, Mg, Mo, Pb, U and V than caps and stalks of Boletus aereus species which, in turn, was from two to four times more enriched in Cu, Se and Tl. Thus, the elemental content of Boletus aereus and Clitopilus prunulus appeared to be species-dependent. The distribution of chemical elements in Boletus aereus was not uniform throughout the whole fruiting body as most elements were significantly bioconcentrated in caps. Furthermore, the fruit bodies of Boletus aereus from the volcanic soil differed both in major and minor elements concentrations from those collected from sedimentary soils. Cadmium and lead concentrations were below the threshold limits for wild mushrooms proposed by EU Directives (2008 and 2015). The elemental content was not significantly influenced by soil pH. Copyright © 2018 Elsevier Inc. All rights reserved.

The effects of copper, manganese and zinc on plant growth and elemental accumulation in the manganese-hyperaccumulator Phytolacca americana.

PubMed

Zhao, Huijun; Wu, Liangqi; Chai, Tuanyao; Zhang, Yuxiu; Tan, Jinjuan; Ma, Shengwen

2012-09-01

Synchrotron radiation X-ray fluorescence (SRXRF) and inductively coupled plasma mass spectrometry were used to estimate major, minor and trace elements in Cu-, Zn- and Mn-treated Phytolacca americana. The effects of the addition of Cu, Zn and Mn on morphological parameters, such as root length, shoot height, and fresh and dry weights of shoots and roots, were also examined. In addition, the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidases (GPX) and catalase (CAT) and the expression of Fe-SOD, Cu/Zn-SOD, metallothionein-2 and glutathione S-transferase (GST) exposed to the highest amounts of Cu, Zn or Mn were detected. Our results confirmed the following: (1) Zn supplementation leads to chlorosis, disturbed elemental homeostasis and decreased concentrations of micro- and macroelements such as Fe, Mg, Mn, Ca and K. Cu competed with Fe, Mn and Zn uptake in plants supplemented with 25 μM Cu. However, no antagonistic interactions took place between Cu, Zn, Mn and Fe uptake in plants supplemented with 100 μM Cu. Mn supplementation at various concentrations had no negative effects on elemental deficits. Mn was co-located with high concentrations of Fe and Zn in mature leaves and the concentrations of macro elements were unchanged. (2) P. americana supplemented with increased concentrations of Zn and Cu exhibited lower biomass production and reduced plant growth. (3) When plants were supplemented with the highest Zn and Cu concentrations, symptoms of toxicity corresponded to decreased SOD or CAT activities and increased APX and GPX activities. However, Mn tolerance corresponded to increased SOD and CAT activities and decreased POD and APX activities. Our study revealed that heavy metals partially exert toxicity by disturbing the nutrient balance and modifying enzyme activities that induce damage in plants. However, P. americana has evolved hyper accumulating mechanisms to maintain elemental balance and redox homeostasis under excess Mn. Copyright © 2012 Elsevier GmbH. All rights reserved.

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of Cr, Fe, Cu, Zn and Se in cereals

NASA Astrophysics Data System (ADS)

Huang, Shih-Yi; Jiang, Shiuh-Jen; Sahayam, A. C.

2014-11-01

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine Cr, Fe, Cu, Zn and Se in several cereal samples. Thioacetamide was used as the modifier to enhance the ion signals. The background ions at the masses of interest were reduced in intensity significantly by using 1.0 mL min- 1 methane (CH4) as reaction cell gas in the dynamic reaction cell (DRC). Since the sensitivities of Cr, Fe, Cu, Zn and Se in different matrices were quite different, standard addition and isotope dilution methods were used for the determination of Cr, Fe, Cu, Zn and Se in these cereal samples. The method detection limits estimated from standard addition curves were about 1, 10, 4, 12 and 2 ng g- 1 for Cr, Fe, Cu, Zn and Se, respectively, in original cereal samples. This procedure has been applied to the determination of Cr, Fe, Cu, Zn and Se whose concentrations are in μg g- 1 (except Cr and Se) in standard reference materials (SRM) of National institute of standards and technology (NIST), NIST SRM 1568a Rice Flour and NIST SRM 1567a Wheat Flour and two cereal samples purchased from a local market. The analysis results of reference materials agreed with certified values at 95% confidence level according to Student's T-test. The results for the real world cereal samples were also found to be in good agreement with the pneumatic nebulization DRC ICP-MS results of the sample solutions.

Challenges in the Search for Magnetic Coupling in 3d/4f Materials: Syntheses, Structures, and Magnetic Properties of the Lanthanide Copper Heterobimetallic Compounds, RE 2 Cu(TeO 3 ) 2 (SO 4 ) 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Jian; Chai, Ping; Diefenbach, Kariem

2014-03-03

Twelve new lanthanide copper heterobimetallic compounds, RE2Cu(TeO3)2(SO4)2 (RE = Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), with two different structural topologies, have been prepared by hydrothermal treatment. Both structure types crystallize in the triclinic space group, Pmore » $$\\bar{1}$$, but the unit cell parameters and structures are quite different. The earlier RE2Cu(TeO3)2(SO4)2 (RE = Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm) share a common structural motif consisting of edge-sharing LnO8 chains and [Cu(TeO3)2(SO4)2]6– units. The later lanthanide version (Yb and Lu) is composed of edge-sharing LnO7 dimers bridged by similar [Cu(TeO3)2(SO4)2]6– units. The change in the structure type can be attributed to the decreasing ionic radii of the lanthanides. The compounds containing RE3+ ions with diamagnetic ground states (Y3+ and Eu3+) exhibit antiferromagnetic ordering at 12.5 K and 15 K, respectively, owing to the magnetic exchange between Cu2+ moments. No magnetic phase transition was observed in all the other phases. The lack of magnetic ordering is attributed to the competing magnetic interactions caused by the presence of paramagnetic RE3+ ions. The magnetism data suggests that substantial 3d–4f coupling only occurs in the Yb analogue.« less

Non-injection synthesis of monodisperse Cu-Fe-S nanocrystals and their size dependent properties.

PubMed

Gabka, Grzegorz; Bujak, Piotr; Żukrowski, Jan; Zabost, Damian; Kotwica, Kamil; Malinowska, Karolina; Ostrowski, Andrzej; Wielgus, Ireneusz; Lisowski, Wojciech; Sobczak, Janusz W; Przybylski, Marek; Pron, Adam

2016-06-01

It is demonstrated that ternary Cu-Fe-S nanocrystals differing in composition (from Cu-rich to Fe-rich), structure (chalcopyrite or high bornite) and size can be obtained from a mixture of CuCl, FeCl3, thiourea and oleic acid (OA) in oleylamine (OLA) using the heating up procedure. This new preparation method yields the smallest Cu-Fe-S nanocrystals ever reported to date (1.5 nm for the high bornite structure and 2.7 nm for the chalcopyrite structure). A comparative study of nanocrystals of the same composition (Cu1.6Fe1.0S2.0) but different in size (2.7 nm and 9.3 nm) revealed a pronounced quantum confinement effect, confirmed by three different techniques: UV-vis spectroscopy, cyclic voltammetry and Mössbauer spectroscopy. The optical band gap increased from 0.60 eV in the bulk material to 0.69 eV in the nanocrystals of 9.3 nm size and to 1.39 eV in nanocrystals of 2.7 nm size. The same trend was observed in the electrochemical band gaps, derived from cyclic voltammetry studies (band gaps of 0.74 eV and 1.54 eV). The quantum effect was also manifested in Mössbauer spectroscopy by an abrupt change in the spectrum from a quadrupole doublet to a Zeeman sextet below 10 K, which could be interpreted in terms of the well defined energy states in these nanoparticles, resulting from quantum confinement. The Mössbauer spectroscopic data confirmed, in addition to the results of XPS spectroscopy, the co-existence of Fe(iii) and Fe(ii) in the synthesized nanocrystals. The organic shell composition was investigated by NMR (after dissolution of the inorganic core) and IR spectroscopy. Both methods identified oleylamine (OLA) and 1-octadecene (ODE) as surfacial ligands, the latter being formed in situ via an elimination-hydrogenation reaction occurring between OLA and the nanocrystal surface.

Self-assembled 3D heterometallic Cu(II)/Fe(II) coordination polymers with octahedral net skeletons: structural features, molecular magnetism, thermal and oxidation catalytic properties.

PubMed

Karabach, Yauhen Y; Guedes da Silva, M Fátima C; Kopylovich, Maximilian N; Gil-Hernández, Beatriz; Sanchiz, Joaquin; Kirillov, Alexander M; Pombeiro, Armando J L

2010-12-06

The new three-dimensional (3D) heterometallic Cu(II)/Fe(II) coordination polymers [Cu(6)(H(2)tea)(6)Fe(CN)(6)](n)(NO(3))(2n)·6nH(2)O (1) and [Cu(6)(Hmdea)(6)Fe(CN)(6)](n)(NO(3))(2n)·7nH(2)O (2) have been easily generated by aqueous-medium self-assembly reactions of copper(II) nitrate with triethanolamine or N-methyldiethanolamine (H(3)tea or H(2)mdea, respectively), in the presence of potassium ferricyanide and sodium hydroxide. They have been isolated as air-stable crystalline solids and fully characterized including by single-crystal X-ray diffraction analyses. The latter reveal the formation of 3D metal-organic frameworks that are constructed from the [Cu(2)(μ-H(2)tea)(2)](2+) or [Cu(2)(μ-Hmdea)(2)](2+) nodes and the octahedral [Fe(CN)(6)](4-) linkers, featuring regular (1) or distorted (2) octahedral net skeletons. Upon dehydration, both compounds show reversible escape and binding processes toward water or methanol molecules. Magnetic susceptibility measurements of 1 and 2 reveal strong antiferromagnetic [J = -199(1) cm(-1)] or strong ferromagnetic [J = +153(1) cm(-1)] couplings between the copper(II) ions through the μ-O-alkoxo atoms in 1 or 2, respectively. The differences in magnetic behavior are explained in terms of the dependence of the magnetic coupling constant on the Cu-O-Cu bridging angle. Compounds 1 and 2 also act as efficient catalyst precursors for the mild oxidation of cyclohexane by aqueous hydrogen peroxide to cyclohexanol and cyclohexanone (homogeneous catalytic system), leading to maximum total yields (based on cyclohexane) and turnover numbers (TONs) up to about 22% and 470, respectively.

Broiler litter as a micronutrient source for cotton: concentrations in plant parts.

PubMed

Tewolde, H; Sistani, K R; Rowe, D E

2005-01-01

Analytically, poultry litter contains nearly all essential micronutrients but the extent of phytoavailability of these nutrients and whether cotton (Gossypium hirsutum L.) and other crop plants can receive adequate amounts of these nutrients from litter is not fully known. The objective of this research was to determine whether cotton receives sufficient amounts of Fe, Cu, Mn, and Zn from litter and estimate the efficiency of cotton in extracting these metal nutrients from litter in the absence of any other source of the micronutrients. The greenhouse research used plastic pots filled with approximately 11 kg of a 2:1 (v/v) sand to vermiculite growing mix. Cotton (cv. Stoneville 474) was grown in the pots fertilized with broiler litter at rates of 30, 60, 90, or 120 g pot(-1) in a factorial combination with four supplemental nutrient solution (NS) treatments. The nutrient solutions consisted of full Hoagland's nutrient solution (NS-full); a solution of the macronutrients N, P, K, Ca, and Mg (NS-macro); a solution of the micronutrients Fe, Zn, Mn, Cu, B, and Mo (NS-micro); and water (NS-none). Based on tissue nutrient analysis, a one-time broiler litter application supplied adequate amounts of Fe, Cu, and Mn to bring the concentration of these nutrients in upper leaves within published sufficiency ranges. Zinc, with <17 mg kg(-1) concentration in the upper leaves, was the only micronutrient below the established sufficiency range regardless of the rate of applied litter. Cotton extracted Fe and Mn more efficiently than Cu or Zn, removing as much as 8.8% of Fe and 7.2% of Mn supplied by 30 g litter pot(-1). In contrast, the extraction efficiency was 1.7% for Cu and 1.9% for Zn. Roots accumulated 58% of the total absorbed Fe and 64% of Cu, and leaves accumulated 32% of the Fe and only 13% of the Cu supplied by litter. In contrast, only 16% of the total absorbed Mn and 23% of Zn accumulated in roots while leaves accumulated 64% of the total Mn and 37% of Zn. These results demonstrate that broiler litter is a valuable source of the metal nutrients supplying Fe, Cu, and Mn in full and Zn in part, but a very large fraction of the litter-supplied metal nutrients remained in the growing mix.

Treatment of oilfield produced water using Fe/C micro-electrolysis assisted by zero-valent copper and zero-valent aluminium.

PubMed

Zhang, Qi

2015-01-01

In this study, the Fe/Cu/C and Fe/Al/C inner micro-electrolysis systems were used to treat actual oilfield produced water to evaluate the feasibility of the technology. Effects of reaction time, pH value, the dosage of metals and activated carbon, and Fe:C mass ratio on the treatment efficiency of wastewater were studied. The results showed that the optimum conditions were reaction time 120 min, initial solution pH 4.0, Fe dosage 13.3 g/L, activated carbon dosage 6.7 g/L, Cu dosage 2.0 g/L or Al dosage 1.0 g/L. Under the optimum conditions, the removal efficiencies of chemical oxygen demand (COD) were 39.3%, 49.7% and 52.6% in the Fe/C, Fe/Cu/C and Fe/Al/C processes, respectively. Meanwhile, the ratio of five-day biochemical oxygen demand to COD was raised from 0.18 to above 0.35, which created favourable conditions for the subsequent biological treatment. All these led to an easy maintenance and low operational cost.

Major, minor, trace and rare earth elements in sediments of the Bijagós archipelago, Guinea-Bissau.

PubMed

Carvalho, Lina; Figueira, Paula; Monteiro, Rui; Reis, Ana Teresa; Almeida, Joana; Catry, Teresa; Lourenço, Pedro Miguel; Catry, Paulo; Barbosa, Castro; Catry, Inês; Pereira, Eduarda; Granadeiro, José Pedro; Vale, Carlos

2018-04-01

Sixty sediment samples from four sites in the Bijagós archipelago were characterized for fine fraction, loss on ignition, major, minor and trace elemental composition (Al, Fe, Ca, Mg, Ti, P, Zr, Mn, Cr, Sr, Ba, B, V, Li, Zn, Ni, Pb, As, Co, U, Cu, Cs and Cd), and the elements of the La-Lu series. Element concentrations were largely explained by the Al content and the proportion of fine fraction content, with the exception of Ca and Sr. Sediments showed enhanced Ti, U, Cr, As and Cd concentrations with respect to estimated upper crust values, most likely mirroring a regional signature. Rare earth elements were in deficit relatively to the North American Shale Composite (NASC), mainly in coarser material. No pronounced Ce-anomaly was observed, while Eu-anomalies were positive in most analyzed sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Air Pollution Study in the Republic of Moldova Using Moss Biomonitoring Technique.

PubMed

Zinicovscaia, Inga; Hramco, Constantin; Duliu, Octavian G; Vergel, Konstantin; Culicov, Otilia A; Frontasyeva, Marina V; Duca, Gheorghe

2017-02-01

Moss biomonitoring using the species Hypnum cupressiforme (Hedw.) and Pleurocarpous sp was applied to study air pollution in the Republic of Moldova. A total of 41 elements (Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Zr, Cd, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Tm, Yb, Hf, Ta, W, Pb, Th, and U) were determined by instrumental epithermal neutron activation analysis and atomic absorption spectrometry. Principal component analysis was used to identify and characterize different pollution sources. Geographical distribution maps were prepared to point out the regions most affected by air pollution and relate this to potential sources of contamination. Median values of the elements studied were compared with data from the European moss biomonitoring program. The cities of Chisinau and Balti were determined to experience particular environmental stress.

On the nature of the Fe-bearing particles influencing hard anodizing behavior of AA 7075 extrusion products

NASA Astrophysics Data System (ADS)

Mukhopadhyay, A. K.

1998-03-01

The deleterious effects of Fe-bearing constituent particles on the fracture toughness of wrought A1 alloys have been known. Recent studies have shown that the presence of Fe-bearing, constituent particles is also determental to the nature and growth of the hard anodic oxide coating formed on such materials. The present study, using a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA), was made to examine the influence of the nature of the Fe-bearing particles on the hard anodizing behavior of AA 7075 extrusion products containing varying amounts of Si, Mn, and Fe impurities. It was found that, in the alloy containing 0.25 wt pct Si, 0.27 wt pct Mn, and 0.25 wt pct Fe, the Fe-bearing constituent particles are based on the Al12(FeMn)3Si phase (bcc with α=1.260 nm). These particles survive the hard anodizing treatment, add resistance to the electrical path, causing a rapid rise in the bath voltage with time, and cause a nonuniform growth of the anodic oxide film. In the materials containing 0.05 wt pct Si, 0.04 wt pct Mn, and 0.18 wt pct Fe, on the other hand, the formation of the Al12(FeMn)3Si-based phase is suppressed, and two different Fe-bearing phases, based on Al-Fe-Cu-Mn-based (simple cubic with a=1.265 nm) and Al7Cu2Fe, respectively form. Neither the Al-Fe-Cu-Mn-based phase nor the Al7Cu2Fe-based phase survive the hard anodizing treatment, and this results in a steady rise in the bath voltage with time and a relatively uniform growth of the anodic oxide film. Consideration of the size of the Fe-bearing, particles reveals that the smaller the particle, the more uniform the growth of the anodic oxide film.

Reactivity of food phenols with iron and copper ions: binding, dioxygen activation and oxidation mechanisms.

PubMed

Nkhili, Ezzohra; Loonis, Michèle; Mihai, Simona; El Hajji, Hakima; Dangles, Olivier

2014-06-01

In this work, the affinity of common dietary phenols (gallic acid, caffeic acid, catechin, and rutin) for iron and copper ions was quantitatively investigated in neutral phosphate buffer as well as the reactivity of the complexes toward dioxygen. Contrasting behaviors were observed: because of the competing phosphate ions, Fe(III) binding is much slower than Fe(II) binding, which is rapidly followed by autoxidation of Fe(II) into Fe(III). With both ions, O2 consumption and H2O2 production are modest and the phenolic ligands are only slowly oxidized. By contrast, metal-phenol binding is fast with both Cu(I) and Cu(II). With Cu(I), O2 consumption and H2O2 production are very significant and the phenolic ligands are rapidly oxidized into a complex mixture of oligomers. The corresponding mechanism with Cu(II) is hampered by the preliminary rate-determining step of Cu(II) reduction by the phenols. The consequences of these findings for the stability and antioxidant activity of plant phenols are discussed.

Microstructure, Mechanical Properties, and Age-Hardening Behavior of an Al-Si-Fe-Mn-Cu-Mg Alloy Produced by Spray Deposition

NASA Astrophysics Data System (ADS)

Feng, Wang; Jishan, Zhang; Baiqing, Xiong; Yongan, Zhang

2011-02-01

It has been recognized generally that the spray-deposited process is an innovative technique of rapid solidification. In this paper, Al-20Si-5Fe-3Mn-3Cu-1Mg alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray-deposited alloy were studied using x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and tensile tests. It is observed that the microstructure of spray-deposited Al-20Si-5Fe-3Mn-3Cu-1Mg alloy is composed of the α-Al,Si and the particle-like Al15(FeMn)3Si2 compounds. The aging process of the alloy was investigated by microhardness measurement, differential scanning calorimetry analysis, and TEM observations. The results indicate that the two types of precipitates, S-Al2CuMg and σ-Al5Cu6Mg2 precipitate from matrix and improve the tensile strength of the alloy efficiently at both the ambient and elevated temperatures (300 °C).

Large spin current injection in nano-pillar-based lateral spin valve

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nomura, Tatsuya; Ohnishi, Kohei; Kimura, Takashi, E-mail: t-kimu@phys.kyushu-u.ac.jp

We have investigated the influence of the injection of a large pure spin current on a magnetization process of a non-locally located ferromagnetic dot in nano-pillar-based lateral spin valves. Here, we prepared two kinds of the nano-pillar-type lateral spin valve based on Py nanodots and CoFeAl nanodots fabricated on a Cu film. In the Py/Cu lateral spin valve, although any significant change of the magnetization process of the Py nanodot has not been observed at room temperature. The magnetization reversal process is found to be modified by injecting a large pure spin current at 77 K. Switching the magnetization bymore » the nonlocal spin injection has also been demonstrated at 77 K. In the CoFeAl/Cu lateral spin valve, a room temperature spin valve signal was strongly enhanced from the Py/Cu lateral spin valve because of the highly spin-polarized CoFeAl electrodes. The room temperature nonlocal switching has been demonstrated in the CoFeAl/Cu lateral spin valve.« less

Effects of trace elements on the crystal field parameters of Nd ions at the surface of Nd{sub 2}Fe{sub 14}B grains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toga, Yuta; Suzuki, Tsuneaki; Sakuma, Akimasa, E-mail: sakuma@solid.apph.tohoku.ac.jp

2015-06-14

Using first-principles calculations, we investigate the positional dependence of trace elements such as O and Cu on the crystal field parameter A{sub 2}{sup 0}, proportional to the magnetic anisotropy constant K{sub u} of Nd ions placed at the surface of Nd{sub 2}Fe{sub 14}B grains. The results suggest the possibility that the A{sub 2}{sup 0} parameter of Nd ions at the (001) surface of Nd{sub 2}Fe{sub 14}B grains exhibits a negative value when the O or Cu atom is located near the surface, closer than its equilibrium position. At the (110) surface, however, O atoms located at the equilibrium position providemore » a negative A{sub 2}{sup 0}, while for Cu additions A{sub 2}{sup 0} remains positive regardless of Cu's position. Thus, Cu atoms are expected to maintain a positive local K{sub u} of surface Nd ions more frequently than O atoms when they approach the grain surfaces in the Nd-Fe-B grains.« less

Copper solubility in a basaltic melt and sulfide liquid/silicate melt partition coefficients of Cu and Fe

NASA Astrophysics Data System (ADS)

Ripley, Edward M.; Brophy, James G.; Li, Chusi

2002-09-01

The solubility of copper in a sulfur-saturated basaltic melt has been determined at 1245°C as a function of fO 2 and fS 2. Copper solubilities at log fO 2 values between -8 and -11 fall into two distinct populations as a function of fS 2. At log fS 2 values < -1.65, sulfide liquid that coexists with the basaltic glass quenches to sulfur-poor bornite solid solution. At log fS 2 values in excess of -1.65, the sulfide liquid quenches to a complex intergrowth of sulfur-rich bornite and intermediate solid solution. Copper solubilities in the low-fS 2 population range from 594 to 1550 ppm, whereas those in the high-fS 2 population range from 80 to 768 ppm. Sulfide liquid/silicate liquid partition coefficients (D) for Cu and Fe range from 480 to 1303 and 0.7 to 13.6, respectively. Metal-sulfur complexing in the silicate liquid is shown to be insignificant relative to metal-oxide complexing for Fe but permissible for Cu at high fS 2 values. On log D Fe (sulfide-silicate) and log D Cu (sulfide-silicate) vs. 1/2 (log fS 2 - log fO 2) diagrams, both fS 2 populations show distinct but parallel trends. The observation of two D values for any fS 2/fO 2 ratio indicates nonideal mixing of species involved in the exchange reaction. The two distinct trends observed for both Cu and Fe are thought to be due to variations in activity coefficient ratios (e.g., γ FeO/γ FeS and γ CuO 0.5/γ CuS 0.5). Results of the experiments suggest that accurate assessments of fS 2/fO 2 ratios are required for the successful numerical modeling of processes such as the partial melting of sulfide-bearing mantle and the crystallization of sulfide-bearing magmas, as well as the interpretation of sulfide mineralogical zoning. In addition, the experiments provide evidence for oxide or oxy-sulfide complexing for Cu in silicate magmas and suggest that the introduction of externally derived sulfur to mafic magma may be an important process for the formation of Cu-rich disseminated magmatic sulfide ore deposits.

Phase formation and magnetic hardening mechanism of TbCu7 type Sm-Fe-N powders

NASA Astrophysics Data System (ADS)

Lu, Cifu; Hong, Xiufeng; Ding, Zhiyi; Shi, Jiaxing; Bao, Xiaoqian; Gao, Xuexu; Zhu, Jie

2018-06-01

(Sm0.7Zr0.3)x(Fe0.9Co0.1)100-x (x = 9.1,10.7,10.9,12.6,13.4) alloys almost consist of TbCu7 type phase were prepared by rapid quenching technique and annealing. A series of TbCu7 type Sm-Zr-Fe-Co-N magnetically hard powders were prepared through nitrogenization of the alloys. With (Sm0.7Zr0.3) content increases, the coercivity increased but magnetization decreases. TbCu7-type nitride powder with coercivity of 10.8 kOe can be obtained when x = 13.6. The initial magnetization curves of the powders indicate that the coercivity should be controlled by pinning mechanism.

Lattice distortion of square iron nitride monolayers induced by changing symmetry of substrate

NASA Astrophysics Data System (ADS)

Hattori, Takuma; Iimori, Takushi; Miyamachi, Toshio; Komori, Fumio

2018-04-01

Rectangular iron nitride monatomic layers are fabricated on the threefold symmetric Cu(111) substrate by taking advantage of the stability of the square nitride film. Two different ordered structures are observed on the Cu(111) substrate by scanning tunneling microscopy after annealing at 510 K and 580 K. Their chemical composition and lattice symmetry are investigated by x-ray photoelectron spectroscopy and low energy electron diffraction. The monolayer film prepared at 580 K is a distorted Fe2N monolayer analogous to a ferromagnetic square Fe2N monolayer with a clock reconstruction on the Cu(001) substrate. The lattice deformation of the square Fe2N monolayer is induced by using Cu(111) with threefold symmetry.

Experimental evidence for the magnetic moment directions of Cr2+ and Cr3+ cations in the spinel ferrites Cux1Crx2Fe3-x1-x2O4

NASA Astrophysics Data System (ADS)

Zhang, X. Y.; Xu, J.; Li, Z. Z.; Qi, W. H.; Tang, G. D.; Shang, Z. F.; Ji, D. H.; Lang, L. L.

2014-08-01

(A)[B]2O4 spinel ferrite samples with the composition Cux1Crx2Fe3-x1-x2O4 (0.0≤x1≤0.284 and 1.04≥x2≥0.656) were prepared by a chemical co-precipitation method. X-ray diffraction patterns indicated that the samples had a single-phase cubic spinel structure. It is interesting that the saturation magnetization of the samples increased when Cu2+ or Cu3+ (with 1 or 2μB of magnetic moment) substituted for Cr2+ or Cr3+ (with 4 or 3μB), which cannot be obviously explained if the magnetic moments of Cr2+ and Cr3+ cations are assumed to be parallel to those of the Fe and Cu cations. However, with the assumption that the magnetic moments of Cr2+ and Cr3+ cations are antiparallel to the Fe and Cu cation moments in spinel ferrites, the dependence on the Cu doping level of the sample magnetic moments at 10 K was fitted successfully, using the quantum-mechanical potential barrier model earlier proposed by our group. Using the cation distributions obtained in the fitting process, the experimental observation that the magnetic moment of the samples increased with increasing Cu doping level was explained. This work therefore provides experimental evidence that the magnetic moments of the Cr2+ and Cr3+ cations are antiparallel to those of the Fe and Cu cations in spinel ferrites.

Zeolite-based SCR catalysts and their use in diesel engine emission treatment

DOEpatents

Narula, Chaitanya K.; Yang, Xiaofan

2016-08-02

A catalyst comprising a zeolite loaded with copper ions and at least one trivalent metal ion other than Al.sup.+3, wherein the catalyst decreases NO.sub.x emissions in diesel exhaust. The trivalent metal ions are selected from, for example, trivalent transition metal ions, trivalent main group metal ions, and/or trivalent lanthanide metal ions. In particular embodiments, the catalysts are selected from Cu--Fe-ZSM5, Cu--La-ZSM-5, Fe--Cu--La-ZSM5, Cu--Sc-ZSM-5, and Cu--In-ZSM5. The catalysts are placed on refractory support materials and incorporated into catalytic converters.

Zeolite-based SCR catalysts and their use in diesel engine emission treatment

DOEpatents

Narula, Chaitanya K; Yang, Xiaofan

2015-03-24

A catalyst comprising a zeolite loaded with copper ions and at least one trivalent metal ion other than Al.sup.+3, wherein the catalyst decreases NO.sub.x emissions in diesel exhaust. The trivalent metal ions are selected from, for example, trivalent transition metal ions, trivalent main group metal ions, and/or trivalent lanthanide metal ions. In particular embodiments, the catalysts are selected from Cu--Fe-ZSM5, Cu--La-ZSM-5, Fe--Cu--La-ZSM5, Cu--Sc-ZSM-5, and Cu--In-ZSM5. The catalysts are placed on refractory support materials and incorporated into catalytic converters.

Melt recharge, f O2-T conditions, and metal fertility of felsic magmas: zircon trace element chemistry of Cu-Au porphyries in the Sanjiang orogenic belt, southwest China

NASA Astrophysics Data System (ADS)

Meng, Xuyang; Mao, Jingwen; Zhang, Changqing; Zhang, Dongyang; Liu, Huan

2018-06-01

The magmatic hydrothermal Pulang Cu deposit (Triassic) and the Beiya Au-Cu deposits (Eocene) are located in the Sanjiang copper porphyry belt, southwest China. Zircon chemistry was used to constrain the magmatic evolution and oxidation state of the porphyries. The results show that porphyries of the Beiya district formed from an early oxidized melt and a later relatively reduced and more evolved magma, whereas Pulang experienced a normal Cu porphyry evolutionary trend. The Pulang porphyries crystallized from more oxidized magma (ΔFMQ + 2.9-4.6, average = 4.0 ± 1.0, n = 3) with an average temperature of 709 ± 6 °C compared to the Beiya porphyries (ΔFMQ + 0.6-3.5, average = 1.9 ± 1.3, n = 5) with a mean magmatic temperature of 780 ± 22 °C. These data, combined with data from other Cu- and Au-rich porphyries in the Sanjiang belt (i.e., Machangjing Cu, Yao'an Au), are consistent with previous experimental work showing that elevated Cu and Au solubilities in magma require oxidizing conditions. A compilation of existing geochemical data for magmatic zircons from fertile and barren porphyry systems worldwide establishes an optimal diagnostic interval on CeIV/CeIII-TTi-in-zircon and (Eu/Eu*)N plots for generating magmatic hydrothermal Cu-Au deposits.

Effects of Coating Materials and Mineral Additives on Nitrate Reduction by Zerovalent Iron

NASA Astrophysics Data System (ADS)

Kim, K. H.; Jeong, H. Y.; Lee, S.; Kang, N.; Choi, H. J.; Park, M.

2015-12-01

In efforts to facilitate nitrate removal, a variety of coating materials and mineral additives were assessed for their effects on the nitrate reduction by zerovalent iron (ZVI). Coated ZVIs were prepared by reacting Fe particles with Cr(III), Co(II), Ni(II), Cu(II), and S(-II) solutions under anoxic conditions, with the resultant materials named Cr/Fe, Co/Fe, Ni/Fe, Cu/Fe, and FeS/Fe, respectively. The mineral additives used, synthesized or purchased, included goethite, magnetite, and hydrous ferric oxide (HFO). Kinetic experiments were performed using air-tight serum vials containing 1.0 g Fe (uncoated or coated forms) in 15 mL of 100 mg NO3×N/L solutions with pH buffered at 7.0. To monitor the reaction progress, the solution phase was analyzed for NO3-, NO2-, and NH4+ on an ion chromatography, while the headspace was analyzed for H2, N2, and O2 on a gas chromatography. By uncoated Fe, ca. 60% of nitrate was reductively transformed for 3.6 h, with NH4+ being the predominant product. Compared with uncoated one, Cr/Fe, Co/Fe, and Cu/Fe showed faster removal rates of nitrate. The observed reactivity enhancement was thought to result from additional reduction of nitrate by H atoms adsorbed on the surface of Cr, Co, or Cu metal. In contrast, both Ni/Fe and FeS/Fe showed slower removal of nitrate than uncoated Fe. In both cases, the coating, which highly disfavors the adsorption of nitrate, would form on the Fe surface. When goethite, HFO, and magnetite were amended, the nitrate reduction by Fe was significantly increased, with the effect being most evident with HFO. Although not capable of reducing nitrate, the mineral additives would serve as crystal nuclei for the corrosion products of Fe, thus making the development of passivation layers on the Fe surface less. In the future, we will perform a kinetic modeling of the experimental data to assess the relative contribution of multiple reaction paths in the nitrate reduction by Fe.

Metallic copper in ordinary chondrites

NASA Technical Reports Server (NTRS)

Rubin, Alan E.

1994-01-01

Metallic Cu of moderately high purity (approximately 985 mg/g Cu, approximately 15 mg/g Ni) occurs in at least 66% of ordinary chondrites (OC) as heterogeneously distributed, small (typically less than or equal to 20 micrometers) rounded to irregular grains. The mean modal abundance of metallic Cu in H, L and LL chondrites is low: 1.0 to 1.4 x 10(exp -4) vol%, corresponding to only 4 - 5 % of the total Cu in OC whole rocks. In more than 75% of the metallic-Cu-bearing OC, at least some metallic Cu occurs at metallic-Fe-Ni-troilite grain boundaries. In some cases it also occurs within troilite, within metallic Fe-Ni, or at the boundaries these phases form with silicates or chromite. Ordinary chondrites that contain a relatively large number of occurrences of metallic Cu/sq mm have a tendency to have experienced moderately high degrees of shock. Shock processes can cause local melting and transportation of metallic Fe-Ni and troilte; because metallic Cu is mainly associated with these phases, it also gets redistributed during shock events. In the most common petrographic assemblage containing metallic Cu, the Cu is adjacent to small irregular troilite grains surrounded by taenite plus tetrataenite; this assemblage resembles fizzed troilite and may have formed by localized shock melting or remelting of a metal-troilite assemblage.

Exposure of Mn and FeSODs, but not Cu/ZnSOD, to NO leads to nitrosonium and nitroxyl ions generation which cause enzyme modification and inactivation: an in vitro study.

PubMed

Niketíc, V; Stojanović, S; Nikolić, A; Spasić, M; Michelson, A M

1999-11-01

The effect of NO treatment in vitro on structural and functional alterations of Cu/Zn, Mn, and Fe type of SODs was studied. Significant difference in response to NO of Cu/ZnSOD compared to the Mn and Fe types was demonstrated. Cu/ZnSOD was shown to be stable with respect to NO: even on prolonged exposure, NO produced negligible effect on its structure and activity. In contrast, both Mn and Fe types were found to be NO-sensitive: exposure to NO led to their fast and extensive inactivation, which was accompanied by extensive structural alterations, including (in some of the samples tested) the cleavage of enzyme polypeptide chains, presumably at His residues of the enzyme metal binding sites. The generation of nitrosonium (NO+) and nitroxyl (NO-) ions in NO treated Mn and FeSODs, which produce enzyme modifications and inactivation, was demonstrated. The physiological and biomedical significance of described findings is briefly discussed.

Fate of corrosion products released from stainless steel in marine sediments and seawater. Part 2. Sequim Bay clayey silt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, R.L.

1982-04-01

This report describes laboratory experiments in which neutron-activated 347 stainless steel specimens were exposed to clayey silt from Sequim Bay, Washington. The properties and trace metal geochemistry of the sediment and the amounts of corrosion products that were released under oxic and reduced conditions and their distribution among different chemical fractions of the sediment are discussed. The distributions of Cr, Mn, Fe, Ni and Cu among different chemical forms in the Sequim Bay sediment show that DTPA removed <10% of extractable Cr, Fe and Mn, approx. 20% of extractable Ni and approx. 30% of extractable Cu. The inorganic fraction (materialmore » soluble in 2.5% acetic acid) accounted for approx. 30% of total extractable Mn and approx. 10% or less of Cr, Fe, Ni and Cu. Major portions of Cr and Cu, and a large amount of Fe were in the organic fraction. Extractable Mn, Fe and Ni were associated with hydrous oxides likely as coatings on the mineral substrate of the sediment. No Co was detectable in any of the extracts. (PSB)« less

Surface-enhanced Raman scattering and DFT investigation of Eriochrome Black T metal chelating compound

NASA Astrophysics Data System (ADS)

Szabó, László; Herman, Krisztian; Leopold, Nicolae; Buzumurgă, Claudia; Chiş, Vasile

2011-06-01

The surface-enhanced Raman scattering (SERS) spectra of Eriochrome Black T (EBT) and its Cu(II), Fe(III), Mn(II) and Pb(II) complexes were recorded using a hydroxylamine reduced silver colloid. Molecular geometry optimization, molecular electrostatic potential (MEP) distribution and vibrational frequencies calculation were performed at B3LYP/6-31G(d) level of theory for the EBT molecule and its Cu(EBT), Fe(EBT) and Mn(EBT) metal complexes. Differentiation between EBT complexes of Cu(II), Fe(III), Mn(II) and Pb(II) is shown by the SERS spectral features of each complex.

Strengthening effect of reduced graphene oxide in steel clad copper rod

NASA Astrophysics Data System (ADS)

Gao, Haitao; Liu, Xianghua; Ai, Zhengrong; Zhang, Shilong; Liu, Lizhong

2016-11-01

Reduced graphene oxide has been extensively used as reinforcing agent owing to their high mechanical properties. In this work, an attempt is made to synthesize steel clad copper rod reinforced with reduced graphene oxide (RGO) by the combination of powder-in-tube and intermediate annealing (IA). Experiments show that the Fe/RGO/Cu composites manifest better mechanical properties than Fe/Cu composites. In the process of groove rolling, RGO acts as effective binder, which can greatly improve the adhesive strength of copper scrap and two metals. Moreover, the strengthening effect of RGO is tightly related to its dispersion state. The RGO diffuses much more uniformly on the metallic substrate under the IA temperature of 1100 °C than 800 °C, which can be characterized by less deformation twins appearing at the interface of core copper and the formation of Fe-RGO-Cu transition belt at the bonding interface. In this case, the peak hardness, tensile strength and shear strength of Fe/RGO/Cu composites are 52 HV, 125 and 41 MPa higher than those of the Fe/Cu composites, respectively. The difference of strengthening effect and mechanisms of RGO under 800 and 1100 °C of IA are systematically discussed by referring to experimental results.

Bioelements in hair of children with selected neurological disorders.

PubMed

Józefczuk, Jan; Kasprzycka, Wiktoria; Czarnecki, Rafał; Graczyk, Alfreda; Józefczuk, Paweł; Krzysztof, Magda; Lampart, Urszula; Mrozowska-Ząbek, Ewa; Surdy, Weronika; Kwiatkowska-Graczyk, Róża

2017-01-01

We have analyzed concentrations of magnesium (Mg), calcium (Ca), copper (Cu), zinc (Zn) and iron (Fe) in hair of a group of 82 children with mental retardation, in which 9 patients suffered from epilepsy, 18 from the Down's syndrome and 55 from cerebral palsy. Girls comprised little over 50% of the patients. In the group of boys with epilepsy, we found Mg, Ca, Cu and Fe deficiency, and normal level of Zn. In the group of girls with epilepsy, apart from low Fe concentration, a high level of Ca, Mg, Zn, and Cu was noted. For girls with the Down's syndrome, a high or normal level of Ca, Mg, Zn and Cu was found, whereas the Fe concentration varied and presented itself in a non-characteristic way. Both groups of children with cerebral palsy, i.e. boys and girls, displayed low Fe concentration in their hair; low Cu level was found in older patients as well. In this group of patients, we also noted high concentrations of Ca, Mg and Zn in girls and normal in boys. A high concentration of Ca in girls with cerebral palsy requires separate analysis. The obtained results could be useful as guidance in the direction and determination of the amount of possible patient nutritional supplementation.

Graphene-Supported Spinel CuFe2O4 Composites: Novel Adsorbents for Arsenic Removal in Aqueous Media

PubMed Central

La, Duong Duc; Nguyen, Tuan Anh; Jones, Lathe A.; Bhosale, Sheshanath V.

2017-01-01

A graphene nanoplate-supported spinel CuFe2O4 composite (GNPs/CuFe2O4) was successfully synthesized by using a facile thermal decomposition route. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Electron Dispersive Spectroscopy (EDS), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the prepared composite. The arsenic adsorption behavior of the GNPs/CuFe2O4 composite was investigated by carrying out batch experiments. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, where the sorption kinetics of arsenic adsorption by the composite were found to be pseudo-second order. The selectivity of the adsorbent toward arsenic over common metal ions in water was also demonstrated. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled column filter test. The GNPs/CuFe2O4 composite exhibited significant, fast adsorption of arsenic over a wide range of solution pHs with exceptional durability, selectivity, and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solution. The highly sensitive adsorption of the material toward arsenic could be potentially employed for arsenic sensing. PMID:28587257

Structural and magnetic analysis of Cu, Co substituted NiFe{sub 2}O{sub 4} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Hakikat; Bala, Kanchan; Negi, N. S.

2016-05-23

In the present work we prepared NiFe{sub 2}O{sub 4}, Ni{sub 0.95}Cu{sub 0.05}Fe{sub 2}O{sub 4} and Ni{sub 0.94}Cu{sub 0.05}Co{sub 0.01} Fe{sub 2}O{sub 4} thin films by metallo-organic decomposition method (MOD) using spin coating technique. The thin films were analyzed by X-ray diffractometer (XRD) and Atomic force microscope (AFM) for structural studies. The XRD patterns confirmed the ferrite phase of thin films. From AFM, we analyzed surface morphology, calculated grain size (GS) and root mean square roughness (RMSR). Room temperature magnetic properties were investigated by vibrating sample magnetometer (VSM).

Commentary on the sphalerite geobarometer

USGS Publications Warehouse

Toulmin, P.; Barton, P.B.; Wiggins, L.B.

1991-01-01

The FeS content of sphalerite in assemblages with pyrite and pyrrhotite has been widely used and widely criticized as a geobarometer. The commonly accepted form of the geobarometer is based on the composition of sphalerite being independent of temperature below about 550??C at all pressures up to at least 10 kbar, but strong thermodynamic arguments require a significant temperature dependence in this region. Most minor components have a negligible effect on the relevant equilibria, but the effect of CuS is somewhat more significant. Molar and partial molar volumes for binary (ZnS-FeS) and ternary (ZnS-FeS-CuS) sphalerite solutions are presented; the ternary data are consistent with charge transfer between Cu and Fe. -from Authors

Synthesis of a single 1,8-naphthalimide fluorophore as a molecular logic lab for simultaneously detecting of Fe3+, Hg2+ and Cu2+

NASA Astrophysics Data System (ADS)

Said, Awad I.; Georgiev, Nikolai I.; Bojinov, Vladimir B.

2018-05-01

A novel fluorescence sensing 1,8-naphthalimide fluorophore is synthesized and investigated. The novel probe comprising two different binding moieties is capable to detect selectively Fe3+ over the other representative metal ions as well as a combination of biologically important cations such as Fe3+, Cu2+ and Hg2+ in the physiological range without an interfering effect of the pHs. Due to the remarkable fluorescence changes in the presence of Fe3+, Hg2+ and Cu2+ ions, INH and AND logic gates are executed and the system is able to act as a single output combinatorial logic circuit with three chemical inputs.

Thermoelectric Properties of Selenospinel Cu6Fe4Sn12Se32

NASA Astrophysics Data System (ADS)

Suekuni, Koichiro; Kunii, Masaru; Nishiate, Hirotaka; Ohta, Michihiro; Yamamoto, Atsushi; Koyano, Mikio

2012-06-01

This report describes thermoelectric properties up to 500 K for polycrystalline selenospinel Cu6Fe4Sn12Se32 samples. Thermal conductivity shows a low value of 1 W/Km because of their structural complexity such as Fe/Sn site disorder. Electrical resistivity ρ varies as exp( T 0/ T 1/4) and thermopower S varies as T 1/2 at low temperatures, which indicates that Mott variable-range hopping is the dominant conduction mechanism. However, at high temperatures (above 350 K), ρ and S decrease simultaneously. The temperature dependences are attributed to the thermal excitation of electrons. The possible band structure for Cu6Fe4Sn12Se32 is examined to clarify the behavior of ρ and S.

Carboniferous-Permian tectonic transition envisaged in two magmatic episodes at the Kuruer Cu-Au deposit, Western Tianshan (NW China)

NASA Astrophysics Data System (ADS)

Yu, Jie; Li, Nuo; Qi, Nan; Guo, Jian-Ping; Chen, Yan-Jing

2018-03-01

The Western Tianshan in NW China is one of the most important gold provinces in the Central Asian Orogenic Belt (CAOB). The recently discovered Kuruer Cu-Au deposit has been interpreted to represent a transition from high-sulfidation epithermal to porphyry mineralization system. In this study, we present new LA-ICP-MS zircon U-Pb ages for the many magmatic rock types at Kuruer, including the Dahalajunshan Formation andesitic tuff (333.2 ± 1.6 Ma), diorite porphyry (269.7 ± 2.0 Ma), slightly-altered (264.4 ± 2.6 Ma) and intensively-altered (270.5 ± 2.5 Ma) albite porphyry. These ages reveal two distinct magmatic episodes: The Early Carboniferous Dahalajunshan Formation (wall rocks) andesitic tuff samples contain narrow ranges of SiO2 (60.29-61.28 wt.%), TiO2 (0.96-0.98 wt.%), Al2O3 (16.55-16.57 wt.%) and Fe2O3T (5.36-5.57 wt.%). The tuff is characterized by LREE enrichment and HFSE depletion, as well as LREE/HREE enrichment ((La/Yb)N = 8.31-8.76) and negative Eu anomalies (δEu = 0.64-0.76). Zircon εHf (t) values are 5.4-8.2, and two-stage Hf model ages (TDM2) are 821-1016 Ma, indicating partial melting of a moderately depleted mantle wedge with Precambrian continental crustal input. The ore-forming Middle Permian diorite porphyry and (quartz) albite porphyry have variable major oxide compositions (e.g., SiO2 = 53.09-53.12 wt.% for the diorite porphyry, 70.84-78.03 wt.% for the albite porphyry, and 74.07-75.03 wt.% for the quartz albite porphyry) but similar chondrite-normalized REE and primitive mantle-normalized multi-element patterns. These porphyries display LREE enrichment and HFSE depletion, as well as elevated LREE/HREE enrichment and negative Eu anomalies. The positive zircon εHf(t) values (11.7-15.9 for the diorite porphyry, 8.9-14.9 for the albite porphyry) and young two-stage Hf model ages (TDM2) (282-542 Ma for the diorite porphyry, 337-717 Ma for the albite porphyry) indicate a major juvenile continental crustal involvement. We propose that the Carboniferous and Middle Permian magmatism was formed in a continental arc and post-collisional settings, respectively, with the latter episode responsible for the Cu-Au mineralization.

CeLa enhanced corrosion resistance of Al-Cu-Mn-Mg-Fe alloy for lithium battery shell

NASA Astrophysics Data System (ADS)

Du, Jiandi; Ding, Dongyan; Zhang, Wenlong; Xu, Zhou; Gao, Yongjin; Chen, Guozhen; Chen, Weigao; You, Xiaohua; Chen, Renzong; Huang, Yuanwei; Tang, Jinsong

2017-11-01

Effects of CeLa addition on the localized corrosion and electrochemical corrosion behavior of Al-Cu-Mn-Mg-Fe lithium battery shell alloy were investigated by immersion testing and electrochemical testing in 0.6 M NaCl solution at different temperatures. Experimental results indicated that CeLa addition resulted in the formation of AlCuCe/La (Al8Cu4Ce and Al6Cu6La) local cathodes and corrosion activity of the main intermetallic particles decreased in the order of Al2CuMg, AlCuCe/La, Al6(Mn, Fe). Corrosion potential shifted positively due to CeLa alloying. Corrosion current density of the CeLa-containing alloy was lower than that of the CeLa-free alloy at room temperature. At room temperature, there was no obvious surface passivation for both alloys. At 80 °C CeLa addition resulted in a wide passive region at the anode polarization region. Electrochemical impedance spectroscopy (EIS) analysis also indicated that corrosion resistance of the CeLa-containing alloy was much higher than that of the CeLa-free alloy.

Atomic level structural modulation during the structural relaxation and its effect on magnetic properties of Fe81Si4B10P4Cu1 nanocrystalline alloy

NASA Astrophysics Data System (ADS)

Cao, C. C.; Zhu, L.; Meng, Y.; Zhai, X. B.; Wang, Y. G.

2018-06-01

The evolution of local structure and defects in the Fe81Si4B10P4Cu1 amorphous alloy during the structural relaxation has been investigated by Mössbauer spectroscopy, positron annihilation lifetime spectroscopy and transmission electron microscopy to explore their effects on magnetic properties of the nanocrystalline. The atomic rearrangements at the early stage of the structural relaxation cause the density increase of the amorphous matrix, but the subsequent atomic rearrangements contribute to the transformation of Fe3B-like atomic arrangements to FeB-like ones with the temperature increasing. As the structural relaxation processes, the released Fe atoms both from Fe3B- and Fe3P-like atomic arrangements result in the formation of new Fe clusters and the increase of Fe-Fe coordination number in the existing Fe clusters and the nucleation sites for α-Fe gradually increase, both of which promote the crystallization. However, the homogeneity of amorphous matrix will be finally destroyed under excessive relaxation temperature, which coarsens nanograins during the crystallization instead. Therefore, soft magnetic properties of the Fe81Si4B10P4Cu1 nanocrystalline alloy can be improved by pre-annealing the amorphous precursor at an appropriate temperature due to the atomic level structural optimization.

Determination of Debye temperatures and Lamb-Mössbauer factors for LnFeO3 orthoferrite perovskites (Ln  =  La, Nd, Sm, Eu, Gd)

NASA Astrophysics Data System (ADS)

Scrimshire, A.; Lobera, A.; Bell, A. M. T.; Jones, A. H.; Sterianou, I.; Forder, S. D.; Bingham, P. A.

2018-03-01

Lanthanide orthoferrites have wide-ranging industrial uses including solar, catalytic and electronic applications. Here a series of lanthanide orthoferrite perovskites, LnFeO3 (Ln  =  La Nd; Sm; Eu; Gd), prepared through a standard stoichiometric wet ball milling route using oxide precursors, has been studied. Characterisation through x-ray diffraction and x-ray fluorescence confirmed the synthesis of phase-pure or near-pure LnFeO3 compounds. 57Fe Mössbauer spectroscopy was performed over a temperature range of 10 K-293 K to observe hyperfine structure and to enable calculation of the recoil-free fraction and Debye temperature (θ D) of each orthoferrite. Debye temperatures (Ln  =  La 474 K Nd 459 K Sm 457 K Eu 452 K Gd 473 K) and recoil-free fractions (Ln  =  La 0.827; Nd 0.817; Sm 0.816; Eu 0.812; Gd 0.826) were approximated through minimising the difference in the temperature dependent experimental centre shift and theoretical isomer shift, by allowing the Debye temperature and isomer shift values to vary. This method of minimising the difference between theoretical and actual values yields Debye temperatures consistent with results from other studies determined through thermal analysis methods. This displays the ability of variable-temperature Mössbauer spectroscopy to approximate Debye temperatures and recoil-free fractions, whilst observing temperature induced transitions over the temperature range observed. X-ray diffraction and Rietveld refinement show an inverse relationship between FeO6 octahedral volume and approximated Debye temperatures. Raman spectroscopy show an increase in the band positions attributed to soft modes of Ag symmetry, Ag(3) and Ag(5) from La to GdFeO3 corresponding to octahedral rotations and tilts in the [0 1 0] and [1 0 1] planes respectively.

Synthesis of inorganic fullerene-like molecules.

PubMed

Bai, Junfeng; Virovets, Alexander V; Scheer, Manfred

2003-05-02

The reaction of [Cp*Fe(eta5-P5)] with Cu(I)Cl in solvent mixtures of CH2Cl2/CH3CN leads to the formation of entirely inorganic fullerene-like molecules of the formula [[Cp*Fe(eta5:eta1:eta1:eta1:eta1:eta1-P5)]12[CuCl]10[Cu2Cl3]5[Cu(CH3CN)2]5] (1) possessing 90 inorganic core atoms. This compound represents a structural motif similar to that of C60: cyclo-P5 rings of [Cp*Fe(eta5-P5)] molecules are surrounded by six-membered P4Cu2 rings that result from the coordination of each of the phosphorus lone pairs to CuCl metal centers, which are further coordinated by P atoms of other cyclo-P5 rings. Thus, five- and six-membered rings alternate in a manner comparable to that observed in the fullerene molecules. The so-formed half shells are joined by [Cu2Cl3]- as well as by [Cu(CH3CN)2]+ units. The spherical body has an inside diameter of 1.25 nanometers and an outside diameter of 2.13 nanometers, which is about three times as large as that of C60.

Influence of Oxygen Partial Pressure during Processing on the Thermoelectric Properties of Aerosol-Deposited CuFeO₂.

PubMed

Stöcker, Thomas; Exner, Jörg; Schubert, Michael; Streibl, Maximilian; Moos, Ralf

2016-03-24

In the field of thermoelectric energy conversion, oxide materials show promising potential due to their good stability in oxidizing environments. Hence, the influence of oxygen partial pressure during synthesis on the thermoelectric properties of Cu-Delafossites at high temperatures was investigated in this study. For these purposes, CuFeO₂ powders were synthetized using a conventional mixed-oxide technique. X-ray diffraction (XRD) studies were conducted to determine the crystal structures of the delafossites associated with the oxygen content during the synthesis. Out of these powders, films with a thickness of about 25 µm were prepared by the relatively new aerosol-deposition (AD) coating technique. It is based on a room temperature impact consolidation process (RTIC) to deposit dense solid films of ceramic materials on various substrates without using a high-temperature step during the coating process. On these dense CuFeO₂ films deposited on alumina substrates with electrode structures, the Seebeck coefficient and the electrical conductivity were measured as a function of temperature and oxygen partial pressure. We compared the thermoelectric properties of both standard processed and aerosol deposited CuFeO₂ up to 900 °C and investigated the influence of oxygen partial pressure on the electrical conductivity, on the Seebeck coefficient and on the high temperature stability of CuFeO₂. These studies may not only help to improve the thermoelectric material in the high-temperature case, but may also serve as an initial basis to establish a defect chemical model.

Silicon induced Fe deficiency affects Fe, Mn, Cu and Zn distribution in rice (Oryza sativa L.) growth in calcareous conditions.

PubMed

Carrasco-Gil, Sandra; Rodríguez-Menéndez, Sara; Fernández, Beatriz; Pereiro, Rosario; de la Fuente, Vicenta; Hernandez-Apaolaza, Lourdes

2018-04-01

A protective effect by silicon in the amelioration of iron chlorosis has recently been proved for Strategy 1 species, at acidic pH. However in calcareous conditions, the Si effect on Fe acquisition and distribution is still unknown. In this work, the effect of Si on Fe, Mn, Cu and Zn distribution was studied in rice (Strategy 2 species) under Fe sufficiency and deficiency. Plants (+Si or-Si) were grown initially with Fe, and then Fe was removed from the nutrient solution. The plants were then analysed using a combined approach including LA-ICP-MS images for each element of interest, the analysis of the Fe and Si concentration at different cell layers of root and leaf cross sections by SEM-EDX, and determining the apoplastic Fe, total micronutrient concentration and oxidative stress indexes. A different Si effect was observed depending on plant Fe status. Under Fe sufficiency, Si supply increased Fe root plaque formation, decreasing Fe concentration inside the root and increasing the oxidative stress in the plants. Therefore, Fe acquisition strategies were activated, and Fe translocation rate to the aerial parts was increased, even under an optimal Fe supply. Under Fe deficiency, +Si plants absorbed Fe from the plaque more rapidly than -Si plants, due to the previous activation of Fe deficiency strategies during the growing period (+Fe + Si). Higher Fe plaque formation due to Si supply during the growing period reduced Fe uptake and could activate Fe deficiency strategies in rice, making it more efficient against Fe chlorosis alterations. Silicon influenced Mn and Cu distribution in root. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Electrochemiluminescence quenching of luminol by CuS in situ grown on reduced graphene oxide for detection of N-terminal pro-brain natriuretic peptide.

PubMed

Li, Xiaojian; Lu, Peng; Wu, Bin; Wang, Yaoguang; Wang, Huan; Du, Bin; Pang, Xuehui; Wei, Qin

2018-07-30

A novel electrochemiluminescence (ECL) signal-off strategy based on CuS in situ grown on reduced graphene oxide (CuS-rGO) quenching luminol/H 2 O 2 system was firstly proposed. Luminol was grafted on the surface of Au@Fe 3 O 4 -Cu 3 (PO 4 ) 2 nanoflowers (Luminol-Au@Fe 3 O 4 -Cu 3 (PO 4 ) 2 ) which exhibited excellent catalytic effect towards the reduction of H 2 O 2 to enhance the ECL intensity of luminol. Cu 3 (PO 4 ) 2 nanoflowers showed large surface area which can immobilize more Fe 3 O 4 and Au nanoparticles. The quenching mechanism of CuS-rGO was due to ECL resonance energy transfer (RET). The spectral overlap between fluorescence spectrum of Luminol-Au@Fe 3 O 4 -Cu 3 (PO 4 ) 2 and UV-vis absorption spectrum of CuS-rGO revealed that resonance energy transfer was possible. Au nanoparticles were immobilized on the surface of CuS-rGO to capture secondary antibodies. After a sandwich-type immunoreaction, a remarkable decrease of ECL signal was observed. Under the optimal conditions, the immunosensor showed excellent performance for N-terminal pro-brain natriuretic peptide (NT-proBNP) detection with a wide detection range from 0.5 pg mL -1 to 20 ng mL -1 and a low detection limit of 0.12 pg mL -1 (S/N = 3). The prepared NT-proBNP immunosensor displayed high sensitivity, excellent stability and good specificity. Copyright © 2018 Elsevier B.V. All rights reserved.

STM/STS studies for interplane disorder effects on the electronic states of the Cu-O plane in Bi2201

NASA Astrophysics Data System (ADS)

Kurosawa, T.; Hatta, G.; Miyazaki, H.; Yamaji, J.; Yoshikawa, K.; Nakagawa, Y.; Shibata, Y.; Yoshida, H.; Oda, M.; Ido, M.; Takeyama, K.; Momono, N.

2015-08-01

STM/STS experiments have been performed in Bi2Sr1.7R0.3CuO6+δ (R-Bi2201) systems with R = La and Eu, which are of a nearly optimal doping level po but have different Tc values, 35 K and 20 K, respectively, to examine interplane disorder effects on the superconducting (SC) gap and the pseudogap (PG) that is accompanied by a checkerboard-type charge order (CCO). We report that as interplane disorders are strengthened by replacing La with Eu in optimal Bi2201, the antinodal PG size Δ∗ increases from ˜ 30meV to ˜ 60meV, which is comparable to the value for an underdoping level p/po ˜ 0.5 in La-Bi2201. On the other hand, the period of CCO in optimal Eu-Bi2201 is the same as in optimal La-Bi2201, about five times lattice constant ˜ 5a along the Cu-O bond directions; it remains unchanged even if the PG develops markedly to the same degree as for p/po ˜ 0.5 in La-Bi2201, whose period is ˜ 4a.

GLOBULAR CLUSTER ABUNDANCES FROM HIGH-RESOLUTION, INTEGRATED-LIGHT SPECTROSCOPY. II. EXPANDING THE METALLICITY RANGE FOR OLD CLUSTERS AND UPDATED ANALYSIS TECHNIQUES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colucci, Janet E.; Bernstein, Rebecca A.; McWilliam, Andrew

2017-01-10

We present abundances of globular clusters (GCs) in the Milky Way and Fornax from integrated-light (IL) spectra. Our goal is to evaluate the consistency of the IL analysis relative to standard abundance analysis for individual stars in those same clusters. This sample includes an updated analysis of seven clusters from our previous publications and results for five new clusters that expand the metallicity range over which our technique has been tested. We find that the [Fe/H] measured from IL spectra agrees to ∼0.1 dex for GCs with metallicities as high as [Fe/H] = −0.3, but the abundances measured for more metal-rich clustersmore » may be underestimated. In addition we systematically evaluate the accuracy of abundance ratios, [X/Fe], for Na i, Mg i, Al i, Si i, Ca i, Ti i, Ti ii, Sc ii, V i, Cr i, Mn i, Co i, Ni i, Cu i, Y ii, Zr i, Ba ii, La ii, Nd ii, and Eu ii. The elements for which the IL analysis gives results that are most similar to analysis of individual stellar spectra are Fe i, Ca i, Si i, Ni i, and Ba ii. The elements that show the greatest differences include Mg i and Zr i. Some elements show good agreement only over a limited range in metallicity. More stellar abundance data in these clusters would enable more complete evaluation of the IL results for other important elements.« less

In situ Fenton reagent generated from TiO2/Cu2O composite film: a new way to utilize TiO2 under visible light irradiation.

PubMed

Zhang, Yong-Gang; Ma, Li-Li; Li, Jia-Lin; Yu, Ying

2007-09-01

TiO2/Cu2O composite is prepared by a simple electrochemical method and coated on glass matrix through a spraying method. The obtained composite is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of TiO2/Cu2O composite films with different ratio of TiO2 and Cu2O on photodegradation of the dye methylene blue under visible light is investigated in detail. It is found that the photocatalytic activity of TiO2/Cu2O composite film with the presence of FeSO4 and EDTA is much higher than that for the similar system with only TiO2 and Cu2O film respectively. Without the presence of FeSO4 and EDTA, there is no degradation for methylene blue. The exploration of the optimized parameters for the degradation of methylene blue by using TiO2/Cu2O composite film as catalyst under visible light was also carried out. The most significant factor is the amount of Ti02 in the composite, and the second significant factor is the concentration of FeSO4. During the degradation of methylene blue under visible light, TiO2/Cu2O composite film generates H202, and Fenton regent is formed with Fe2+ and EDTA, which is detected in this study. The mechanism for the great improvement of photocatalytic activity of TiO2/Cu2O composite film under visible light is proposed by the valence band theory. Electrons excitated from TiO2/Cu2O composite under visible light are transferred from the conduction band of Cu2O to that of Ti02. The formed intermediate state of Ti 3+ ion is observed by X-ray photoelectron spectroscopy (XPS) on the TiO/Cu2O composite film. Additionally, the accumulated electrons in the conduction band of TiO2 are transferred to oxygen on the TiO2 surface for the formation of O2- or O2(2-), which combines with H+ to form H2O2. The evolved H202 with FeSO4 and EDTA forms Fenton reagentto degrade methylene blue. Compared to the traditional Fenton reagent, this new kind of in situ Fenton reagent generated from TiO2/Cu2O composite film does not need to supply H202. It is expected to be easily recycled, which may reduce second pollution and the cost of wastewater treatment. Moreover, this TiO/Cu2O composite film with FeSO4 and EDTA provides a new way to take advantage of TiO2 under visible light.

Correlation between ionic size and valence state of tetra, penta and hexavalent B-site substitution with solubility limit, phase transformation and multiferroic properties of Bi0.875Eu0.125FeO3

NASA Astrophysics Data System (ADS)

Mumtaz, Fiza; Jaffari, G. Hassnain; Hassan, Qadeer ul; Shah, S. Ismat

2018-06-01

We present detailed comparative study of effect of isovalent i.e. Eu+3 substitution at A-site and tetra (Ti+4, Zr+4), penta (V+5) and hexavalent (W+6) substitutions at B-site in BiFeO3. Eu+3 substitution led to phase transformation and exhibited mixed phases i.e. rhombohedral and orthorhombic, while tetravalent substituents (Ti+4 and Zr+4) led to stabilization of cubic phase. In higher valent (i.e. V+5 and W+6) cases solubility limit was significantly reduced where orthorhombic phase was observed as in the case of parent compound. Phase transformation as a consequence of increase in microstrain and chemical pressure induced by the substituent has been discussed. Solubility limit of different B-site dopants i.e. Zr, W and V was extracted to 5%, 2% and 2%, respectively. Extra phases in various cases were Bi2Fe4O9, Bi25FeO40, Bi14W2O27, and Bi23V4O44.5 and their fractional amount have been quantified. Ti was substituted up to 15% and has been observed to be completely soluble in the parent compound. Solubility limits depends on ionic radii mismatch and valance difference of Fe+3 and dopant, in which valance difference plays more dominant role. Solubility limit and phase transformation has been explained in terms of change in bond strength and tolerance factor induced by incorporation of dopant which depend on its size and valence state. Detail optical, dielectric, ferroelectric, magnetic and transport properties of Eu and Ti co-doped samples and selected low concentration B-site doped compositions (i.e. 2%) have presented and discussed. Two d-d transitions and three charge transfer transitions were observed within UV-VIS range. Both change in cell volume for the same phase and transformation in crystal structure affects the band gap. Increase in room temperature dielectric constant and saturation polarization was also found to increase in case of Eu-Ti co-doped samples with increasing concentration of Ti. Substitution of Eu at A-site and Ti at B-site led to observation of weak ferromagnetism. Effect of extra phases on ferroelectricity and transport properties have also been discussed.

NiFeCo/Cu superlattices with high magnetoresistive sensitivity and weak hysteresis

NASA Astrophysics Data System (ADS)

Bannikova, N. S.; Milyaev, M. A.; Naumova, L. I.; Krinitsina, T. P.; Patrakov, E. I.; Proglyado, V. V.; Chernyshova, T. A.; Ustinov, V. V.

2016-10-01

The microstructure and the magetoresistive characteristics of [NiFeCo/Cu]8 superlattices prepared by magnetron sputtering with various thickness of the buffer NiFeCr layer and exhibiting a giant magnetoresistive effect have been studied. It has been found that these nanostructures are formed with a strong or weak hysteresis depending on the structure (bcc or fcc) formed in the NiFeCr buffer layer. The method of the substantial decrease in the hysteresis loop width of the magnetoresistance by using the composite Ta/NiFeCr buffer layer has been suggested.

Influence of Composition on the Environmental Impact of a Cast Aluminum Alloy

PubMed Central

Gómez, Patricia; Elduque, Daniel; Sarasa, Judith; Pina, Carmelo; Javierre, Carlos

2016-01-01

The influence of alloy composition on the environmental impact of the production of six aluminum casting alloys (Al Si12Cu1(Fe), Al Si5Mg, Al Si9Cu3Zn3Fe, Al Si10Mg(Fe), Al Si9Cu3(Fe)(Zn) and Al Si9) has been analyzed. In order to perform a more precise environmental impact calculation, Life Cycle Assessment (LCA) with ReCiPe Endpoint methodology has been used, with the EcoInvent v3 AlMg3 aluminum alloy dataset as a reference. This dataset has been updated with the material composition ranges of the mentioned alloys. The balanced, maximum and minimum environmental impact values have been obtained. In general, the overall impact of the studied aluminum alloys varies from 5.98 × 10−1 pts to 1.09 pts per kg, depending on the alloy composition. In the analysis of maximum and minimum environmental impact, the alloy that has the highest uncertainty is AlSi9Cu3(Fe)(Zn), with a range of ±9%. The elements that contribute the most to increase its impact are Copper and Tin. The environmental impact of a specific case, an LED luminaire housing made out of an Al Si12Cu1(Fe) cast alloy, has been studied, showing the importance of considering the composition. Significant differences with the standard datasets that are currently available in EcoInvent v3 have been found. PMID:28773536

Influence of Composition on the Environmental Impact of a Cast Aluminum Alloy.

PubMed

Gómez, Patricia; Elduque, Daniel; Sarasa, Judith; Pina, Carmelo; Javierre, Carlos

2016-05-25

The influence of alloy composition on the environmental impact of the production of six aluminum casting alloys (Al Si12Cu1(Fe), Al Si5Mg, Al Si9Cu3Zn3Fe, Al Si10Mg(Fe), Al Si9Cu3(Fe)(Zn) and Al Si9) has been analyzed. In order to perform a more precise environmental impact calculation, Life Cycle Assessment (LCA) with ReCiPe Endpoint methodology has been used, with the EcoInvent v3 AlMg3 aluminum alloy dataset as a reference. This dataset has been updated with the material composition ranges of the mentioned alloys. The balanced, maximum and minimum environmental impact values have been obtained. In general, the overall impact of the studied aluminum alloys varies from 5.98 × 10 -1 pts to 1.09 pts per kg, depending on the alloy composition. In the analysis of maximum and minimum environmental impact, the alloy that has the highest uncertainty is AlSi9Cu3(Fe)(Zn), with a range of ±9%. The elements that contribute the most to increase its impact are Copper and Tin. The environmental impact of a specific case, an LED luminaire housing made out of an Al Si12Cu1(Fe) cast alloy, has been studied, showing the importance of considering the composition. Significant differences with the standard datasets that are currently available in EcoInvent v3 have been found.

Copper-containing plastocyanin used for electron transport by an oceanic diatom.

PubMed

Peers, Graham; Price, Neil M

2006-05-18

The supply of some essential metals to pelagic ecosystems is less than the demand, so many phytoplankton have slow rates of photosynthetic production and restricted growth. The types and amounts of metals required by phytoplankton depends on their evolutionary history and on their adaptations to metal availability, which varies widely among ocean habitats. Diatoms, for example, need considerably less iron (Fe) to grow than chlorophyll-b-containing taxa, and the oceanic species demand roughly one-tenth the amount of coastal strains. Like Fe, copper (Cu) is scarce in the open sea, but notably higher concentrations of it are required for the growth of oceanic than of coastal isolates. Here we report that the greater Cu requirement in an oceanic diatom, Thalassiosira oceanica, is entirely due to a single Cu-containing protein, plastocyanin, which--until now--was only known to exist in organisms with chlorophyll b and cyanobacteria. Algae containing chlorophyll c, including the closely related coastal species T. weissflogii, are thought to lack plastocyanin and contain a functionally equivalent Fe-containing homologue, cytochrome c6 (ref. 9). Copper deficiency in T. oceanica inhibits electron transport regardless of Fe status, implying a constitutive role for plastocyanin in the light reactions of photosynthesis in this species. The results suggest that selection pressure imposed by Fe limitation has resulted in the use of a Cu protein for photosynthesis in an oceanic diatom. This biochemical switch reduces the need for Fe and increases the requirement for Cu, which is relatively more abundant in the open sea.

Layered magnetic structures: Antiferromagnetic-type interlayer coupling and magnetoresistance due to antiparallel alignment

NASA Astrophysics Data System (ADS)

Grünberg, P.; Demokritov, S.; Fuss, A.; Vohl, M.; Wolf, J. A.

1991-04-01

Layered Fe/Cr structures are known to display antiferromagnetic-type interlayer coupling and a new magnetoresistance (MR) effect due to antiparallel magnetization alignment. The strength of the coupling is found to be similar in multilayered structures and in double layers. The oscillatory behavior of the coupling, previously found by Parkin, More, and Roche [Phys. Rev. Lett. 64, 2304 (1990)] on sputtered polycrystalline samples, is here confirmed for epitaxial samples, obtained by thermal evaporation. The new MR effect is interpreted as due to a spin-dependent scattering of the electrons at the Fe-Cr interfaces. The investigations have been extended to Fe/V, Fe/Mn, Fe/Cu, Co/Au, Co/Cr, and Co/Cu structures where the antiparallel alignment of the ferromagnetic layers is obtained via hysteresis effects. A MR effect due to antiparallel alignment, which is strong for Co/Au and Co/Cu but weak in the other cases, has been found.

Degradation of high energetic and insensitive munitions compounds by Fe/Cu bimetal reduction.

PubMed

Koutsospyros, Agamemnon; Pavlov, Julius; Fawcett, Jacqueline; Strickland, David; Smolinski, Benjamin; Braida, Washington

2012-06-15

A reductive technology based on a completely mixed two-phase reactor (bimetallic particles and aqueous stream) was developed for the treatment of aqueous effluents contaminated with nitramines and nitro-substituted energetic materials. Experimental degradation studies were performed using solutions of three high energetics (RDX, HMX, TNT) and three insensitive-munitions components (NTO, NQ, DNAN). The study shows that, on laboratory scale, these energetic compounds are easily degraded in solution by suspensions of bimetallic particles (Fe/Ni and Fe/Cu) prepared by electro-less deposition. The type of bimetal pair (Fe/Cu or Fe/Ni) does not appear to affect the degradation kinetics of RDX, HMX, and TNT. The degradation of all components followed apparent first-order kinetics. The half-lives of all compounds except NTO were under 10 min. Additional parameters affecting the degradation processes were solids loading and initial pH. Copyright © 2012 Elsevier B.V. All rights reserved.

Evaporation Mechanism of Cu from Liquid Fe Containing C and S

NASA Astrophysics Data System (ADS)

Jung, Sung-Hoon; Kang, Youn-Bae

2016-08-01

A number of liquid-gas experiments were carried out in order to elucidate evaporation mechanism of Cu from liquid Fe containing C and S. Rate of Cu evaporation in liquid Fe droplets at 1873 K (1600 °C) was determined using electromagnetic levitation equipment. Evaporation rate of the Cu under various conditions (flow rate of gas mixtures, initial C, and S concentrations) was examined. It was found from a series of kinetic analyses of the experimental data that Cu evaporates in forms of Cu(g) and CuS(g). As was reported for the Sn evaporation from liquid iron (Jung et al. Met. Mater. Trans. 46B, 250-258, 2014), S plays two roles for the evaporation of Cu: accelerating the rate by forming CuS(g) and decelerating the rate by blocking evaporation sites. As a result of these combinatorial effects, the evaporation of Cu is decelerated at low S content, but is accelerated at high S content. Based on the elucidated mechanism, an evaporation model equation for Cu was developed in the present study, which takes into account (1) evaporation of Cu in the two forms (Cu(g) and CuS(g)), (2) surface blocking by S using ideal Langmuir adsorption, and (3) effect of C. The obtained rate constant of a reaction Cu i + S i = CuS i (g), k CuS R , is 1.37 × 10-9 m4 mol-1 s-1, and the residual rate constant, k CuS r , is 4.11 × 10-10 m4 mol-1 s-1 at 1873 K (1600 °C). Both of them were found to be one order lower than those for Sn evaporation.

Effects of chemical composition of fly ash on efficiency of metal separation in ash-melting of municipal solid waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okada, Takashi, E-mail: t-okada@u-fukui.ac.jp; Tomikawa, Hiroki

2013-03-15

Highlights: ► Separation of Pb and Zn from Fe and Cu in ash-melting of municipal solid waste. ► Molar ratio of Cl to Na and K in fly ash affected the metal-separation efficiency. ► The low molar ratio and a non-oxidative atmosphere were better for the separation. - Abstract: In the process of metal separation by ash-melting, Fe and Cu in the incineration residue remain in the melting furnace as molten metal, whereas Pb and Zn in the residue are volatilized. This study investigated the effects of the chemical composition of incineration fly ash on the metal-separation efficiency of themore » ash-melting process. Incineration fly ash with different chemical compositions was melted with bottom ash in a lab-scale reactor, and the efficiency with which Pb and Zn were volatilized preventing the volatilization of Fe and Cu was evaluated. In addition, the behavior of these metals was simulated by thermodynamic equilibrium calculations. Depending on the exhaust gas treatment system used in the incinerator, the relationships among Na, K, and Cl concentrations in the incineration fly ash differed, which affected the efficiency of the metal separation. The amounts of Fe and Cu volatilized decreased by the decrease in the molar ratio of Cl to Na and K in the ash, promoting metal separation. The thermodynamic simulation predicted that the chlorination volatilization of Fe and Cu was prevented by the decrease in the molar ratio, as mentioned before. By melting incineration fly ash with the low molar ratio in a non-oxidative atmosphere, most of the Pb and Zn in the ash were volatilized leaving behind Fe and Cu.« less

Microstructural Characterization of Base Metal Alloys with Conductive Native Oxides for Electrical Contact Applications

NASA Astrophysics Data System (ADS)

Senturk, Bilge Seda

Metallic contacts are a ubiquitous method of connecting electrical and electronic components/systems. These contacts are usually fabricated from base metals because they are inexpensive, have high bulk electrical conductivities and exhibit excellent formability. Unfortunately, such base metals oxidize in air under ambient conditions, and the characteristics of the native oxide scales leads to contact resistances orders of magnitude higher than those for mating bare metal surface. This is a critical technological issue since the development of unacceptably high contact resistances over time is now by far the most common cause of failure in electrical/electronic devices and systems. To overcome these problems, several distinct approaches are developed for alloying base metals to promote the formation of self-healing inherently conductive native oxide scales. The objective of this dissertation study is to demonstrate the viability of these approaches through analyzing the data from Cu-9La (at%) and Fe-V binary alloy systems. The Cu-9 La alloy structure consists of eutectic colonies tens of microns in diameter wherein a rod-like Cu phase lies within a Cu6La matrix phase. The thin oxide scale formed on the Cu phase was found to be Cu2O as expected while the thicker oxide scale formed on the Cu6La phase was found to be a polycrystalline La-rich Cu2O. The enhanced electrical conductivity in the native oxide scale of the Cu-9La alloy arises from heavy n-type doping of the Cu2O lattice by La3+. The Fe-V alloy structures consist of a mixture of large elongated and equiaxed grains. A thin polycrystalline Fe3O4 oxide scale formed on all of the Fe-V alloys. The electrical conductivities of the oxide scales formed on the Fe-V alloys are higher than that formed on pure Fe. It is inferred that this enhanced conductivity arises from doping of the magnetite with V+4 which promotes electron-polaron hopping. Thus, it has been demonstrated that even in simple binary alloy systems one can obtain a dramatic reduction in the contact resistances of alloy oxidized surfaces as compared with those of the pure base metals.

Spectrophotometric Determination of the Hole Concentration in the Superconductor YBa2Cu3O(sub 7-x)

ERIC Educational Resources Information Center

Hoppe, Jack I.; Malati, Mounir A.

2005-01-01

An experimental study of ceramic superconductors namely YBa2Cu3O(sub 7-x), which illustrates the use of spectrophotometry, based on the electronic spectra of complexes of Fe(II), Fe(III) and Cu(II) to better understand the stoichiometry of YBCO is described. The results from this experiment are in good agreement with those obtained by the…

Textured Nd2Fe14B flakes with enhanced coercivity

NASA Astrophysics Data System (ADS)

Cui, B. Z.; Zheng, L. Y.; Marinescu, M.; Liu, J. F.; Hadjipanayis, G. C.

2012-04-01

Morphology, structure, and magnetic properties of the [001] textured Nd2Fe14B nanocrystalline flakes prepared by surfactant-assisted high energy ball milling (HEBM) and subsequent annealing were studied. These flakes have a thickness of 80-200 nm, a length of 0.5-10 μm, and an average grain size of 10-14 nm. The addition of some amount of Dy, Nd70Cu30 alloy, and an appropriate post annealing increased the coercivity iHc of the Nd2Fe14B flakes. iHc was 3.7, 4.3, and 5.7 kOe for the Nd15.5Fe78.5B6, Nd14Dy1.5Fe78.5B6 and 83.3 wt.% Nd14Dy1.5Fe78.5B6 + 16.7 wt.% Nd70Cu30 flakes prepared by HEBM for 5 h in heptane with 20 wt.% oleylamine, respectively. After annealing at 450 °C for 0.5 h, their iHc increased to 5.1, 6.2, and 7.0 kOe, respectively. Anisotropic magnetic behavior was found in all of the as-milled and annealed flakes. Both, the thickening of Nd-rich phase at grain boundaries via diffusion of Nd70Cu30 and the surface modification of the Nd2Fe14B flake could be the main reasons for the coercivity enhancement in the as-milled and annealed Nd70Cu30-added Nd2Fe14B flakes.

Colloid formation and metal transport through two mixing zones affected by acid mine drainage near Silverton, Colorado

USGS Publications Warehouse

Schemel, L.E.; Kimball, B.A.; Bencala, K.E.

2000-01-01

Stream discharges and concentrations of dissolved and colloidal metals (Al, Ca, Cu, Fe, Mg, Mn, Pb, and Zn), SO4, and dissolved silica were measured to identify chemical transformations and determine mass transports through two mixing zones in the Animas River that receive the inflows from Cement and Mineral Creeks. The creeks were the dominant sources of Al, Cu, Fe, and Pb, whereas the upstream Animas River supplied about half of the Zn. With the exception of Fe, which was present in dissolved and colloidal forms, the metals were dissolved in the acidic, high-SO4 waters of Cement Creek (pH 3.8). Mixing of Cement Creek with the Animas River increased pH to near-neutral values and transformed Al and some additional Fe into colloids which also contained Cu and Pb. Aluminium and Fe colloids had already formed in the mildly acidic conditions in Mineral Creek (pH 6.6) upstream of the confluence with the Animas River. Colloidal Fe continued to form downstream of both mixing zones. The Fe- and Al-rich colloids were important for transport of Cu, Pb, and Zn, which appeared to have sorbed to them. Partitioning of Zn between dissolved and colloidal phases was dependent on pH and colloid concentration. Mass balances showed conservative transports for Ca, Mg, Mn, SO4, and dissolved silica through the two mixing zones and small losses (< 10%) of colloidal Al, Fe and Zn from the water column.

Composition gradient, structure, stress, roughness and magnetic properties of 5-500 nm thin NiFe films obtained by electrodeposition

NASA Astrophysics Data System (ADS)

Gong, Jie; Riemer, Steve; Kautzky, Michael; Tabakovic, Ibro

2016-01-01

The composition gradients of 5-500 nm thin NiFe films on Cu and NiP substrates obtained by electrodeposition in stirred plating solutions at pH 3.0 on 8 in wafers were studied. It was found that the average elemental composition of the NiFe changes during electrodeposition with steep downturns of Fe-content, from 58 to 50 wt% Fe, in composition gradient zone near the substrate interface in the thickness range 5-250 nm depending on the electrode substrate (Cu and NiP). The increase of Fe-content in the composition gradient zone is accompanied by the increase of coercivity, Hc, magnetic flux saturation, Bs, saturation magnetostriction, λs, increase of dimensionless roughness, ρrms, and change of stress, σ. The coercivity (easy and hard axis) follows the Neel's relation Hc=ct-n (t is thickness and c is a constant). The mechanisms related to the change of coercivity of the NiFe films deposited on different substrates (Cu and NiP) are discussed in terms of material properties of these films.

Effect of 3d doping on the electronic structure of BaFe2As2.

PubMed

McLeod, J A; Buling, A; Green, R J; Boyko, T D; Skorikov, N A; Kurmaev, E Z; Neumann, M; Finkelstein, L D; Ni, N; Thaler, A; Bud'ko, S L; Canfield, P C; Moewes, A

2012-05-30

The electronic structure of BaFe(2)As(2) doped with Co, Ni and Cu has been studied by a variety of experimental and theoretical methods, but a clear picture of the dopant 3d states has not yet emerged. Herein we provide experimental evidence of the distribution of Co, Ni and Cu 3d states in the valence band. We conclude that the Co and Ni 3d states provide additional free carriers to the Fermi level, while the Cu 3d states are found at the bottom of the valence band in a localized 3d(10) shell. These findings help shed light on why superconductivity can occur in BaFe(2)As(2) doped with Co and Ni but not Cu.

Investigation of magnetization dynamics damping in Ni80Fe20/Nd-Cu bilayer at room temperature

NASA Astrophysics Data System (ADS)

Fan, Wei; Fu, Qiang; Qian, Qian; Chen, Qian; Liu, Wanling; Zhou, Xiaochao; Yuan, Honglei; Yue, Jinjin; Huang, Zhaocong; Jiang, Sheng; Kou, Zhaoxia; Zhai, Ya

2018-05-01

Focusing on the Ni80Fe20 (Py)/Nd-Cu bilayers, the magnetization dynamic damping from spin pumping effect is investigated systematically by doping itinerant Cu in rear earth metal Nd. Various Ta/Py/Nd1-xCux/Ta/Si films with x = 0%, 16%, 38%, 46% and 58% are prepared by magnetron sputtering. For every content of Cu, the thickness of Nd-Cu layer is changed from 1 nm to 32 nm. The damping coefficient increases with increasing the thickness of Nd-Cu layer, which shows the trend of the spin pumping behavior. Also, with increasing Cu concentration in the Nd-Cu layer, the damping coefficient decreases, implying that the spin-orbit coupling in Nd-Cu layer is indeed cut down by high itinerant of Cu dopants. It is interesting that the spin diffusion length (λSD) in the Nd-Cu layer for different Cu dopants is not found to increase monotonously.