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1

Structural, Magnetic, and Superconducting Properties of Single Crystals of Yttrium BARIUM(2) COPPER(3-X) Iron(x) OXYGEN(7-DELTA)  

NASA Astrophysics Data System (ADS)

Measurements of the magnetic properties, superconducting properties, and the structural features of rm YBa_2 Cu_{3-x} Fe_ x O_ {7-delta} were done on single crystals with concentrations of iron x = 0.06, 0.09, 0.15, and 0.24. The magnetic measurement analysis in a Curie-Weiss fashion gave an effective magnetic moment corresponding to a low spin state (t^5_ {2g}) of iron(III). The lack of magnetic anisotropy between the ab plane and the c direction, and the uniform antiferromagnetic ordering seen with increasing iron concentrations support the existence of iron clusters. Superconducting measurements in these single crystals showed the magnitude of lower critical field (H _{rm c1}) in both directions to be similar to that obtained in untwinned rm YBa_2 Cu_{3-x} Fe_ x O_ {7-delta} and also showed a decrease in superconducting anisotropy with increased iron concentration. Similarly, upper critical field (H_{rm c2 }) showed a decrease in anisotropy between the two directions, and a change in the mass ratio, and derived Ginzberg-Landau superconducting quantities. All of these effects on H_{rm c1 } and H_{rm c2} are also consistent with a cluster model of Fe. The lattice parameters of the X-ray analysis of the single crystals showed an apparent orthorhombic-tetragonal transition at an iron concentration of x = 0.15. The structural analysis showed that the coupling distances between the CuO planes and chains are responsible for the change in superconducting anisotropy with increasing iron concentration.

Nunez-Hilerio, Luis

2

Adsorption of oxygen on clean and barium covered copper surfaces: an XPS, UPS and AES study  

NASA Astrophysics Data System (ADS)

XPS studies of oxygen on barium covered copper surface show two types of dissociatively chemisorbed species, viz. O x- (529.5 eV) and Oy- (531.6 eV) ( x) < y < 2). This is supported by He II spectra which show two peaks at 6 and 9.2 eV below EF. While dissociatively chemisorbed oxygen on clean copper seen at 530 eV is strongly held even up to 700 K, the oxygen on barium covered surface starts desorbing at 450 K. The surface stoichiometry of oxygen to barium has been estimated both as functions of barium coverage and of temperature for a given barium concentration. The Cu(L 3VV)/Cu(L 3M 23M 23) Auger ratio technique has been employed to show charge transfer from barium to copper on the barium covered surface and from copper to oxygen on subsequent oxygen adsorption.

Ayyoob, M.; Hegde, M. S.

1984-11-01

3

Absorbing properties and structural design of microwave absorbers based on carbonyl iron and barium ferrite  

Microsoft Academic Search

Carbonyl iron and barium ferrite powder (BaZn1.5Co0.5Fe16O27) were prepared in this work. The complex permittivity and permeability spectra for rubber radar absorbing materials employing carbonyl iron and barium ferrite powders were measured. A database describing the frequency dependence of the permittivities and permeabilities of the carbonyl iron and barium ferrite microwave absorbers with various powder percentage compositions in 2 18

Y. B. Feng; T. Qiu; C. Y. Shen

2007-01-01

4

Absorbing properties and structural design of microwave absorbers based on carbonyl iron and barium ferrite  

Microsoft Academic Search

Carbonyl iron and barium ferrite powder (BaZn1.5Co0.5Fe16O27) were prepared in this work. The complex permittivity and permeability spectra for rubber radar absorbing materials employing carbonyl iron and barium ferrite powders were measured. A database describing the frequency dependence of the permittivities and permeabilities of the carbonyl iron and barium ferrite microwave absorbers with various powder percentage compositions in 2–18GHz was

Y. B. Feng; T. Qiu; C. Y. Shen

2007-01-01

5

Nanoscale inhomogeneities in yttrium-barium-copper-oxide (YBCO) superconductors  

NASA Astrophysics Data System (ADS)

X-ray diffraction studies at the Advanced Photon Source reveal that nanoscale inhomogeneities, electronic or structural in origin, form in yttrium-barium-copper-oxide (YBa_2Cu_3O_6+x) superconductors and coexist with the superconducting (SC) state. Diffuse scattering from these inhomogeneous superstructures is due to atomic displacements with respect to equilibrium lattice sites (Z. Islam et al. Phys. Rev. B 66, 92501 (2002)), that are characterized by a wavevector of the form q=(q_x,0,0), where qx varies with hole doping from 2 unit cells (along shorter Cu-O-Cu direction) for very low doping to 4 unit cells at optimal doping. Interestingly, while these superstructures are 3-dimensionally ordered when the SC state is weakened (e.g., at x=0.4), as the doping increases, they become quasi 1D with correlation lengths comparable to SC coherence lengths in these cuprates. Recent first-principles calculations (D. de Fontaine et al., to be published) for the x=0.63 compound show that atomic displacements consistent with experimental data can be the result of ordering of O vacancies in YBCO. Models for various superstructures and their role in the phase diagram will be discussed.

Islam, Zahirul; Sinha, S. K.; Lang, J. C.; Liu, X.; Haskel, D.; Moss, S. C.; Srajer, G.; Veal, B. W.; Wermeille, D.; Lee, D. R.; Haeffner, D. R.; Welp, U.; Wochner, P.

2004-03-01

6

Fabrication, characterization and microwave properties of polyurethane nanocomposites reinforced with iron oxide and barium titanate  

E-print Network

with iron oxide and barium titanate nanoparticles Z. Guo a,*, S.-E. Lee a , H. Kim a , S. Park a , H.T. Hahn titanate nanoparticles fabricated by the surface-initiated-polymerization approach were investigated the introduction of the dielectric barium titanate nanoparticle into Fe2O3/PU nanocomposites. The permeability

Guo, John Zhanhu

7

Verification of d-wave pairing symmetry by microwave intermodulation distortion measurements in yttrium barium copper oxide  

E-print Network

We report measurements of the temperature and power dependence of the microwave frequency intermodulation distortion (IMD) in high quality pulsed laser deposition (PLD) Yttrium Barium Copper Oxide (YBCO) on LaAlO3 substrate. ...

Park, Sang-Hoon, Ph. D. Massachusetts Institute of Technology

2004-01-01

8

Absorbing properties and structural design of microwave absorbers based on carbonyl iron and barium ferrite  

NASA Astrophysics Data System (ADS)

Carbonyl iron and barium ferrite powder (BaZn 1.5Co 0.5Fe 16O 27) were prepared in this work. The complex permittivity and permeability spectra for rubber radar absorbing materials employing carbonyl iron and barium ferrite powders were measured. A database describing the frequency dependence of the permittivities and permeabilities of the carbonyl iron and barium ferrite microwave absorbers with various powder percentage compositions in 2-18 GHz was created. Based on the database, the single-layer and double-layer absorbers were designed and prepared, and their microwave absorption properties were investigated. The results indicate that the carbonyl iron powder prepared via thermal decomposition of iron pentacarbonyl is single cubic iron and of spherical shape. The barium ferrite powder is single W-type ferrite and a hexagonal flake. The absorption band of the double-layer microwave absorber is obviously more than that of the single-layer absorber. The double-layer microwave absorbers with reflection loss <-13 dB over the range of 6-18 GHz and reflection loss <-8 dB over the range of 2-18 GHz were prepared. The thicknesses of the absorbers are only 3.6 and 3.7 mm, respectively.

Feng, Y. B.; Qiu, T.; Shen, C. Y.

2007-11-01

9

Copper deficiency increases iron absorption in the rat.  

PubMed

Release of iron from enterocytes and hepatocytes is thought to require the copper-dependent ferroxidase activity of hephaestin (Hp) and ceruloplasmin (Cp), respectively. In swine, copper deficiency (CD) impairs iron absorption, but whether this occurs in rats is unclear. By feeding a diet deficient in copper, CD was produced, as evidenced by the loss of copper-dependent plasma ferroxidase I activity, and in enterocytes, CD reduced copper levels and copper-dependent oxidase activity. Hematocrit was reduced, and liver iron was doubled. CD reduced duodenal mucosal iron and ferritin, whereas CD increased iron absorption. Duodenal mucosal DMT1-IRE and ferroportin1 expression remained constant with CD. When absorption in CD rats was compared with that seen normally and in iron-deficient anemic animals, strong correlations were found among mucosal iron, ferritin, and iron absorption, suggesting that the level of iron absorption was appropriate given that the erythroid and stores stimulators of iron absorption are opposed in CD. Because CD reduced the activity of Cp, as evidenced by copper-dependent plasma ferroxidase I activity and hepatocyte iron accumulation, but iron absorption increased, it is unlikely that the ferroxidase activity of Hp is important and suggests another function for this protein in the export of iron from the enterocyte during iron absorption. Also, the copper-dependent ferroxidase activity of Cp does not appear important for iron efflux from macrophages, because Kupffer cells of the liver and nonheme iron levels of the spleen were normal during copper deficiency, suggesting another role for Cp in these cells. PMID:12760904

Thomas, Carla; Oates, Phillip S

2003-11-01

10

Understanding oxygen vacancy migration and clustering in barium strontiumcobalt iron oxide  

Microsoft Academic Search

In order to understand vacancy clustering and phase stability in oxygen-deficient barium strontium cobalt iron oxide (BSCF), we predict stability and activation energies for oxygen vacancy migration with plane wave Density Functional Theory. Using symmetry constrained search and Nudged Elastic Band method, we characterize the transition states for an oxygen anion moving into a nearby oxygen vacancy site that is

Shruba Ganopadhyay; Artëm E. Masunov; Talgat Inerbaev; Jaruwan Mesit; Ratan K. Guha; Ahmad K. Sleiti; Jay S. Kapat

2010-01-01

11

Synthesis and properties of barium titanate solid solution thin films deposited on copper substrates  

NASA Astrophysics Data System (ADS)

Barium titanate thin films were deposited via chemical solution deposition using a hybrid-chelate chemistry directly on copper foil substrates. A process was developed to crystallize and densify the ferroelectric films at 900°C by using a reductive atmosphere containing nitrogen, hydrogen, water vapor, and oxygen impurities such that film constituents were oxidized to form barium titanate and the foil substrate remained metallic. The crystallized films are polycrystalline with equiaxed morphology and average grain diameters in excess of 100 mn. The dielectric properties exhibit permittivities in excess of 1800 at room temperature and zero bias with tunabilites of greater than 90% and high field loss tangents of less than 1%. The phase transition temperature and temperature coefficient of capacitance modified by partially substituting zirconium, hafnium, and tin for titanium. The resulting films were single phase and the phase transition shifts were consistent with bulk materials. A reduction in permittivity was observed for increasing substituent level and was attributed to a reduction in grain size for both barium titanate zirconate and barium titanate hafnate. Processing conditions were chosen to stabilize Sn2+ during the firing process in an attempt to flux the system and increase grain size. The barium titanate stannate films had less reduction in grain size per substituent level than either zirconium or hafnium, however a similar reduction in permittivity was observed. The diminished dielectric response was explained by a defect reaction involving divalent tin and oxygen vacancies that quenched the extrinsic domain response to the dielectric constant. Barium borate fluxes were used to improve densification and crystallinity. Barium borate additions between 0 and 3% uniformly increased grain size and density, while levels greater than 3% resulted in anomalous grain growth. Films with exaggerated grains show tetragonal peak splitting in the X-ray diffraction patterns, consistent with bulk barium titanate. In materials without exaggerated grain growth, dielectric measurements revealed permittivities in excess of 3000 at room temperature (for average grain sizes of approximately 160 nm). This value is equivalent to the finest-prepared bulk ceramics and substantially greater than any polycrystalline film ever reported. This has been attributed to in improvement in film crystallinity. These two accomplishments - tetragonal crystal symmetry and permittivities in excess of 3000 - represent dramatic breakthroughs in ferroelectric thin film technology. (Abstract shortened by UMI.)

Ihlefeld, Jon Fredrick

12

Copper and nickel partitioning in iron meteorites  

NASA Astrophysics Data System (ADS)

Trace element analyses using proton induced X-ray emission and synchrotron X-ray fluorescence have been made on metal and troilite from nine iron meteorites representing five geochemical groups. Nickel and copper distribution coefficients D (troilite/metal) vary by factors of 600 and 20, respectively, correlate positively with kamacite bandwidth and correlate negatively with bulk nickel content. Meteorites with bulk Ni of less than 10 percent have Cu-enriched troilite while those with Ni greater than 10 percent have Cu-depleted troilite. Since magmatic evolution and partial melting will produce Cu-enriched troilite only, the observation of Cu-depleted troilite in Ni-rich meteorites is evidence for subsolidus reequilibration, a process which reduces D(Cu) by transfer of Cu to exsolving metal. Elemental redistribution may have played an important role in establishing the present chemical trends in iron meteorites.

Sutton, S. R.; Delaney, J. S.; Smith, J. V.; Prinz, M.

1987-10-01

13

In-situ formation of barium ferrite in iron doped "tetragonal tungsten bronze": Elaboration of room temperature multiferroic composites  

E-print Network

1 In-situ formation of barium ferrite in iron doped "tetragonal tungsten bronze": Elaboration Ba2LnFeNb4O15 (Ln = rare earth) with the "tetragonal tungsten bronze" (TTB) structure have correlated their room temperature multiferroics properties to the occurrence of barium ferrite parasitic phases

Paris-Sud XI, Université de

14

Iron versus Copper II. Principles and Applications in Bioinorganic Chemistry.  

ERIC Educational Resources Information Center

Discusses the differences between iron and copper. Describes various aspects of the behaviors of these two elements, including those of biological and environmental significance. Addresses the evolution of the atmosphere and sedimentary ore formation, the phylogeny of iron and copper, and some anthropological notes regarding the use of the metals.…

Ochiai, Ei-Ichiro

1986-01-01

15

Old Iron, Young Copper: from Mars to Venus  

Microsoft Academic Search

Iron and copper are metals which play an important role in the living world. From a brief consideration of their chemistry and biochemistry we conclude that the early chemistry of life used water soluble ferrous iron while copper was in the water-insoluble Cu(I) state as highly insoluble sulphides. The advent of oxygen was a catastrophic event for most living organisms,

R. R. Crichton; J.-L. Pierre

2001-01-01

16

Synthesis, crystal structure and properties of calcium and barium hydroxyapatites containing copper ions in hexagonal channels  

Microsoft Academic Search

Coloured ceramic calcium and barium phosphate apatites containing copper ions were prepared by solid state reactions at 1100°C. Single crystals were grown by melting the ceramics in Bi?M?Cu?O (M=Ca, Ba) fluxes at 1300°C, and subsequent controlled cooling. The powders were characterised by X-ray diffraction, IR and UV–vis diffuse reflectance spectroscopy and SQUID magnetometry. The single crystals have empirical formulas Ca5(PO4)3Cu0.27O0.86Hy

Andrey S. Karpov; Jürgen Nuss; Martin Jansen; Pavel E. Kazin; Yury D. Tretyakov

2003-01-01

17

Chemical synthesis of battery grade super-iron barium and potassium Fe(VI) ferrate compounds  

Microsoft Academic Search

The chemical preparation of high purity potassium and barium ferrates for alkaline electrochemical storage are presented. The synthesized salts are used to demonstrate a variety of high capacity super-iron (Zn anode) alkaline AAA cell configurations which utilize these Fe(V) salts. Results of 500 days, full stability, of the synthesized K2FeO4 are presented. Synthetic pathways yielding 80–100g of 96.5–99.5% pure K2FeO4

Stuart Licht; Vera Naschitz; Bing Liu; Susanta Ghosh; Nadezhda Halperin; Leonid Halperin; Dmitri Rozen

2001-01-01

18

Short-term effects of intratracheal installations of yttrium barium copper oxide  

SciTech Connect

Inhalation exposures to the new high-temperature ({Tc}) superconductor (SC) materials can occur during manufacturing and fabrication processes. In this exploratory study, we examined the pulmonary response to the deposition of an yttrium barium copper oxide SC powder. Groups of Sprague-Dawley rats were intratracheally instilled with either 10 mg or 20 mg of SC in phosphate-buffered saline (PBS) or with PBS only. The animals were sacrificed 60 days later for histopathologic assessments of their lungs. Lung lesions in the 10-mg SC group were found mainly in alveolar ducts and proximal alveoli. The lesions consisted of variably sized foci of interstitial thickening involving accumulations of macrophages. These interstitial aggregates were often times centered around one or more extracellular crystals, which, presumably, were retained SC product. Trichome stains also demonstrated the presence of fibrosis in the walls of alveoli surrounding the granulomas. Similar interstitial-macrophage accumulations and fibrosis were observed in rats instilled with 20 mg of SC. However, alveolus like structures lined by ciliated cuboidal epithelium near interstitial granulomas were additionally found in the lungs of some of the animals in this latter group. These results suggest SC material of the yttrium barium copper oxide type may represent a potential exposure hazard to the lung.

London, J.E.; Newkirk, L.R.; Lehnert, B.E.

1990-12-01

19

Chemical synthesis of battery grade super-iron barium and potassium Fe(VI) ferrate compounds  

NASA Astrophysics Data System (ADS)

The chemical preparation of high purity potassium and barium ferrates for alkaline electrochemical storage are presented. The synthesized salts are used to demonstrate a variety of high capacity super-iron (Zn anode) alkaline AAA cell configurations which utilize these Fe(V) salts. Results of 500 days, full stability, of the synthesized K 2FeO 4 are presented. Synthetic pathways yielding 80-100 g of 96.5-99.5% pure K 2FeO 4 and BaFeO 4 are presented, and the products of these syntheses are demonstrated to provide a high energy electrochemical discharge in a variety of AAA alkaline cells. BaFeO 4 super-iron alkaline AAA cells provide over 0.8 W h during 2.8 ? discharge, yielding over 200% higher capacity than conventional alkaline batteries. The barium super-iron cell configurations studied provide higher capacity than the potassium super-iron alkaline cell configurations studied.

Licht, Stuart; Naschitz, Vera; Liu, Bing; Ghosh, Susanta; Halperin, Nadezhda; Halperin, Leonid; Rozen, Dmitri

20

Effect of zinc on copper and iron bioavailability as influenced by dietary copper and fat source  

SciTech Connect

In a number of experiments, they have observed that liver copper levels of young male rats fed low zinc diets were essentially the same as liver copper levels of rats fed adequate zinc. Liver iron levels of rats fed low zinc diets, however, tended to be markedly higher than liver iron levels of rats fed adequate zinc. Increases in dietary zinc (up to 200 ppm) were generally associated with decreases in liver iron deposition, but had little effect on liver copper deposition. Iron bioavailability appeared to be enhanced when fat sources high in saturated fatty acids were used, and there was evidence that the type of dietary fat influenced the effect of zinc on iron bioavailability. Liver copper deposition, however, did not appear to be markedly affected by the type of dietary fat suggesting that copper bioavailability is less affected by fat source. Increases in dietary copper were associated with increases in liver copper levels and decreases in liver iron levels of rats fed increasing levels of zinc. These data suggest that potential interrelationships between dietary factors not being considered as experimental variables could have significant effects on results and on the interrelationships between dietary variables which are being studied.

Magee, A.C.; Jones, B.P.; Lin, F.; Sinthusek, G.; Frimpong, N.A.; Wu, S.

1986-03-05

21

Reductive iron uptake by Candida albicans: role of copper, iron and the TUP1 regulator  

Microsoft Academic Search

High-affinity iron uptake by a ferrous permease in the opportunistic pathogen Candida albicans is required for virulence. Here this iron uptake system has been characterized by investigating three distinct activities: an externally directed surface ferric reductase, a membrane-associated PPD ( p- phenylenediamine) oxidase and a cellular ferrous iron transport activity. Copper was required for the PPD oxidase and ferrous transport

Simon A. B. Knight; Emmanuel Lesuisse; Robert Stearman; Richard D. Klausner; Andrew Dancis

22

Iron, copper, and iron regulatory protein 2 in Alzheimer's disease and related dementias  

Microsoft Academic Search

Accumulating evidence implicates a role for altered iron and copper metabolism in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). However, imbalances in the levels of the various forms of iron at different stages of AD have not been examined. In this pilot study we extracted and measured the levels of loosely bound, non-heme and total iron and

Shino Magaki; Ravi Raghavan; Claudius Mueller; Kerby C. Oberg; Harry V. Vinters; Wolff M. Kirsch

2007-01-01

23

Effect of excess iron and copper on physiology of aquatic plant Spirodela polyrrhiza (L.) Schleid.  

PubMed

To elucidate effect of chemical reagents addition on growth of aquatic plants in restoration of aquatic ecosystem, Spirodela polyrrhiza (L.) Schleid was used to evaluate its physiological responses to excess iron (Fe(3+)) and copper (Cu(2+)) in the study. Results showed that accumulation of iron and copper both reached maximum at 100 mg L(-1) iron or copper after 24 h short-term stress, but excess iron and copper caused plants necrosis or death and colonies disintegration as well as roots abscission at excess metal concentrations except for 1 mg L(-1) iron. Significant differences in chlorophyll fluorescence (Fv/Fm) were observed at 1-100 mg L(-1) iron or copper. The synthesis of chlorophyll and protein as well as carbohydrate and the uptake of phosphate and nitrogen were inhibited seriously by excess iron and copper. Proline content decreased with increasing iron or copper concentration, however, MDA content increased with increasing iron or copper concentration. PMID:19260045

Xing, Wei; Huang, Wenmin; Liu, Guihua

2010-04-01

24

The copper-iron connection: hereditary aceruloplasminemia.  

PubMed

Hereditary aceruloplasminemia is an autosomal recessive disorder of iron homeostasis due to loss-of-function mutations in the ceruloplasmin gene. Affected individuals may present in adulthood with evidence of hepatic iron overload, diabetes, peripheral retinal degeneration, dystonia, dementia, or dysarthria. Laboratory studies demonstrate microcytic anemia, elevated serum ferritin, and a complete absence of serum ceruloplasmin ferroxidase activity. Consistent with the observed neurologic findings, magnetic resonance imaging reveals iron accumulation within the basal ganglia. Histologic studies detect abundant iron in hepatocytes, reticuloendothelial cells of the liver and spleen, beta cells of the pancreas, and astrocytes and neurons throughout the central nervous system. Characterization of this disorder reveals an essential role for ceruloplasmin in determining the rate of iron efflux from cells with mobilizable iron stores and provides new insights into the mechanisms of human iron metabolism. PMID:12382203

Nittis, Thalia; Gitlin, Jonathan D

2002-10-01

25

Iron may play a role in pancreatic atrophy in copper deficiency  

SciTech Connect

The present study was undertaken to determine if pancreatic atrophy in copper deficient rats fed fructose is associated with excessive iron deposition. Weanling male and female rats were fed a copper deficient or copper adequate diet containing 62% carbohydrate as either fructose or starch. Another group of weanling rats consumed a copper deficient diet containing fructose that was low in iron. After consuming their respective diets for five weeks, the highest pancreatic iron concentration was seen in male rats consuming the copper deficient diet containing fructose. These animals also exhibited pancreatic atrophy. In contrast, neither copper deficient female rats fed fructose nor males fed starch exhibited pancreatic atrophy and their pancreata did not contain high levels of iron. In addition, reducing the availability of dietary iron in copper deficient rats fed fructose decreased pancreatic iron concentration and ameliorated the pathology. The data suggest that pancreatic atrophy in copper deficiency may be related to iron deposition in that tissue.

Fields, M.; Lewis, C.G.; Lure, M.D. (Georgetown Univ. Medical Center, Washington, DC (United States) Dept. of Agriculture, Beltsville, MD (United States) Univ. of Maryland, College Park (United States))

1991-03-15

26

Iron inhibits neurotoxicity induced by trace copper and biological reductants  

Microsoft Academic Search

The extracellular microenvironment of the brain contains numerous biological redox agents, including ascorbate, glutathione, cysteine and homocysteine. During ischemia\\/reperfusion, aging or neurological disease, extracellular levels of reductants can increase dramatically owing to dysregulated homeostasis. The extracellular concentrations of transition metals such as copper and iron are also substantially elevated during aging and in some neurodegenerative disorders. Increases in the extracellular

Anthony R. White; Kevin J. Barnham; Xudong Huang; Irene Voltakis; Konrad Beyreuther; Colin L. Masters; Robert A. Cherny; Ashley I. Bush; Roberto Cappai

2004-01-01

27

Copper Nqr and NMR Study of Metal-Substituted Yttrium BARIUM(2) COPPER(3) OXYGEN(7) and Yttrium BARIUM(2) COPPER(4) OXYGEN(8)  

NASA Astrophysics Data System (ADS)

Pulsed nuclear quadrupole resonance (NQR) and nuclear magnetic resonance (NMR) have been used to investigate the effect of metal-substitution for copper in YBa_2Cu_3O_7 (YBCO123) and YBa_2Cu_4O_8 (YBCO124). Among many metal substitutions, Zn has an especially dramatic effect in suppressing the superconducting temperature T_{c}, and hence superconductivity. More interesting is that Zn and Fe have the same T_{c} suppression effect in YBCO124. This study focuses on the Zn substitutions in YBCO123 and Zn, Fe, and Co substitutions in YBCO124. In Zn doped YBCO123, Cu(2), plane site, NQR spectra and the frequency dependence of the spin-lattice relaxation rates have been measured over a temperature range from 77 K to 300 K to study the correlation of the suppression of the relaxation rate with the distance between the probe Cu nuclei and the impurity. It is found that the relaxation rate is insensitive to the variation of the NQR resonance frequency. However, by comparing the results of the Zn doped YBCO124 with those of YBCO123, it can be concluded that the suppression of the relaxation rate for both YBCO compounds in the normal state is caused by destruction of short-range antiferromagnetic correlation with substitution of nonmagnetic ion Zn on the Cu(2) sites. NQR and NMR measurements were carried out on both Cu(2), plane, and Cu(1), chain sites, for various concentrations of Zn, Fe, and Co dopants in YBCO124 over a temperature range from 77 K to 300 K. A strong correlation of the enhancement of Cu(2) spin lattice relaxation rate and suppression of superconductivity by impurities was found. The temperature dependence of the Cu(2) NMR linewidth exhibits a strong RKKY type exchange interaction below 225 K for Zn and Fe doped samples, which indicates the formation of the local magnetic moment. The enhancement of the relaxation rate is caused by the local magnetic moment Fe^ {+3} ion and the moments on Cu(2) neighbors when Zn^{+2} is substituted on Cu(2). This study gives us a clear picture of the spin pseudogap behavior in the high temperature superconductor cuprates. It also suggests that the magnetic moment on the CuO_2 plane may relate to the suppression of T_{c} in metal-substituted YBCO124.

Cheng, Show-Jye

28

Iron supplementation in pregnancy and breastfeeding and iron, copper and zinc status of lactating women from a human milk bank.  

PubMed

This study evaluated the influence of iron supplementation in pregnancy and breastfeeding on iron status of lactating women from a Brazilian Human Milk Bank. Blood and mature breast milk samples were collected from 145 women for assessment of iron status, as well as copper and zinc status. Haemoglobin, serum iron and ferritin were determined, respectively, by electronic counting, colorimetry and chemiluminescence. Transferrin and ceruloplasmin were analysed by nephelometry. Serum copper and zinc were measured by atomic absorption spectrophotometry, and serum alkaline phosphatase was measured by a colorimetric method. Iron, zinc and copper in breast milk were determined by spectrometry. Mean values of iron, copper and zinc (blood and breast milk) were compared by ANOVA, followed by Tukey's test. Iron supplementation was beneficial to prevent anaemia in pregnancy but not effective to treat anaemia. During breastfeeding, iron supplementation had a negative effect on maternal copper status, confirming an interaction between these micronutrients. PMID:23070740

Mello-Neto, Julio; Rondó, Patricia Helen Carvalho; Oshiiwa, Marie; Morgano, Marcelo Antonio; Zacari, Cristiane Zago; dos Santos, Mariana Lima

2013-04-01

29

The effects of copper and iron deficiencies in the chick  

E-print Network

rusty swords in drinking water to cure anemia. Both Syndenham in 1664 and Willis in 1681 showed that giving cholybeate water or salts of iron to chlorotic indivi- duals would restore the pink color to their cheeks (Fowler, 1936) . The presence... In 1928, Hart et al. demonstrated the importance of copper and iron in correcting the anemia of rats fed diets consisting only of milk. It was found that young weanling rats placed on a diet of whole cow's milk developed anemia in six to eight weeks...

McGhee, Flin Cameron

2012-06-07

30

Methods for making a supported iron-copper catalyst  

DOEpatents

A catalyst is described for the synthesis of hydrocarbons from CO+H.sub.2 utilizing a porous Al.sub.2 O.sub.3 support impregnated with iron and copper and optionally promoted with an alkali metal. The use of an Al.sub.2 O.sub.3 support results in the suppression of heavy waxes (C.sub.26 + hydrocarbons), particularly in slurry phase operation, when compared to unsupported or co-precipitated catalysts.

Dyer, Paul N. (Allentown, PA); Pierantozzi, Ronald (Macungie, PA)

1986-01-01

31

Iron oxide-copper-gold deposits: an Andean view  

Microsoft Academic Search

Iron oxide-copper-gold (IOCG) deposits, defined primarily by their elevated magnetite and\\/or hematite contents, constitute a broad, ill-defined clan related to a variety of tectono-magmatic settings. The youngest and, therefore, most readily understandable IOCG belt is located in the Coastal Cordillera of northern Chile and southern Peru, where it is part of a volcano-plutonic arc of Jurassic through Early Cretaceous age.

Richard H. Sillitoe

2003-01-01

32

Promotion of atherogenesis by copper or iron-Which is more likely?  

SciTech Connect

Iron levels increase in atherosclerotic lesions in cholesterol fed-rabbits and play a role in atherosclerosis. We investigated whether copper also rises. Male New Zealand White rabbits were fed high-cholesterol diets for 8 weeks. After sacrifice, lesion sizes were determined, and elemental analyses of the lesion and unaffected artery wall performed using nuclear microscopy. Unlike iron, lesion copper is decreased by about half compared with the unaffected artery wall, and much less copper than iron is present. Our data suggest that iron may be more likely to play a role in the promotion of atherosclerosis than copper.

Rajendran, Reshmi [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, MD7, 8 Medical Drive, Singapore 117597 (Singapore); Department of Biochemistry, National University of Singapore, MD7, 8 Medical Drive, Singapore 117597 (Singapore); Ren, Minqin [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, MD7, 8 Medical Drive, Singapore 117597 (Singapore); Ning, Pan [Department of Biochemistry, National University of Singapore, MD7, 8 Medical Drive, Singapore 117597 (Singapore); Tan Kwong Huat, Benny [Department of Pharmacology, National University of Singapore, MD7, 8 Medical Drive, Singapore 117597 (Singapore); Halliwell, Barry [Department of Biochemistry, National University of Singapore, MD7, 8 Medical Drive, Singapore 117597 (Singapore)]. E-mail: bchbh@nus.edu.sg; Watt, Frank [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, MD7, 8 Medical Drive, Singapore 117597 (Singapore)

2007-02-02

33

Metal-Responsive Transcription Factors That Regulate Iron, Zinc, and Copper Homeostasis in Eukaryotic Cells  

Microsoft Academic Search

Iron, copper, and zinc are all essential nutrients. The elec- tron transfer properties of iron and copper are fundamental to processes such as respiration and photosynthesis. Zinc forms the catalytic center in numerous enzymes and has an important structural role in a wide range of proteins. However, all these metals can be toxic if their levels and distribution are not

Julian C. Rutherford; Amanda J. Bird

2004-01-01

34

Oxidoreductive coupling of thiols with aryl halides catalyzed by copper on iron.  

PubMed

Synthesis and utilization of a simple copper on iron catalyst in the coupling of aryl halides with thiols through disulfide intermediate is reported. The iron support of copper catalyst ensures reductive media for the coupling, allows easy removal of the metals by outer magnetic field and enables the recycling of the catalyst. PMID:21079878

Kovács, Szabolcs; Novák, Zoltán

2011-02-01

35

Raman Studies of Yttrium BARIUM(2) (COPPER(1-X) NICKEL(X)(3) OXYGEN(7-DELTA) and (yttrium BARIUM(2) COPPER(3) OXYGEN(7))(M)(PRASEODYMIUM BARIUM(2) COPPER(3) OXYGEN(7))(N) Superlattices  

NASA Astrophysics Data System (ADS)

Raman measurements on YBa_2(Cu _{1-x}Ni_{x})O_ {7-delta} and (YBa _2Cu_3O_7)_{m}(PrBa _2Cu_3O_7)_{n} superlattices have been performed. The unusual softening of the B_{1g} -like phonon of YBa_2Cu_3O _7 is studied as a function of T _{c} by substituting up to 6 atomic percent nickel for Cu. The abrupt onset and small temperature range over which the softening occurs in undoped YBa_2Cu_3O_7 are modified upon doping with the softening occurring well above T_{c} and continuing smoothly to 10K when T_{ c} is reduced to 71K. The phonon linewidth in the doped films shows no anomalies, regardless of Ni concentration. In contrast, the self-energies of the A_{g} modes associated with the plane copper (Cu(2)) and apical oxygen (O4) atoms reveal normal thermal behavior for all films. We conclude that an additional mechanism, besides strong coupling of phonons to superconducting electrons, contributes to the B_{1g} phonon anomalies in the Ni-doped samples. The Raman spectra from artificial structures of c- and a-axis oriented superlattices (YBa _2Cu_3O_7)_{m}(PrBa _2Cu_3O_7)_{n} with 1 < m, n < 15 are, in general, similar to those obtained from samples of the individual constituents. The observed Raman active vibrations of the superlattice are readily identified through comparison with spectra from the bulk components. The dependence of the phonon frequencies on m and n shows a significant softening of the vibration associated with the apical oxygen atom (O(4)) in PrBa_2Cu_3O _7 with reductions in the Pr-layer thickness (d_{Pr}). The modifications to the self energy of this phonon for both superlattice orientations only occur when d_{Pr} < 25A and therefore establish the primary importance of the Pr-layer thickness in affecting the observed softening. These phonon renormalizations are consistent with charge redistribution in the immediate vicinity (~10A) of the interface arising from the unequal Fermi energies associated with the alternating layers. The degree of inter-diffusion between Pr and Y sites is shown to be negligible with no detectable interfacial alloying. Reminiscent of behavior in bulk YBa_2Cu_3O _7, the out-of-phase O(2)-O(3) phonon confined to Y-layers as small as two unit cells softens below the superconducting transition temperature T_ {c}. The corresponding phonon localized to the Pr layers shows no softening down to n = 1 and therefore suggests the absence of proximity induced superconductivity in the rm PrBa_2Cu _3O_7 layers.

Ham, Kyungmin

36

Copper-dependent iron assimilation pathway in the model photosynthetic eukaryote Chlamydomonas reinhardtii.  

PubMed

The unicellular green alga Chlamydomonas reinhardtii is a valuable model for studying metal metabolism in a photosynthetic background. A search of the Chlamydomonas expressed sequence tag database led to the identification of several components that form a copper-dependent iron assimilation pathway related to the high-affinity iron uptake pathway defined originally for Saccharomyces cerevisiae. They include a multicopper ferroxidase (encoded by Fox1), an iron permease (encoded by Ftr1), a copper chaperone (encoded byAtx1), and a copper-transporting ATPase. A cDNA, Fer1, encoding ferritin for iron storage also was identified. Expression analysis demonstrated that Fox1 and Ftrl were coordinately induced by iron deficiency, as were Atx1 and Fer1, although to lesser extents. In addition, Fox1 abundance was regulated at the posttranscriptional level by copper availability. Each component exhibited sequence relationship with its yeast, mammalian, or plant counterparts to various degrees; Atx1 of C. reinhardtii is also functionally related with respect to copper chaperone and antioxidant activities. Fox1 is most highly related to the mammalian homologues hephaestin and ceruloplasmin; its occurrence and pattern of expression in Chlamydomonas indicate, for the first time, a role for copper in iron assimilation in a photosynthetic species. Nevertheless, growth of C. reinhardtii under copper- and iron-limiting conditions showed that, unlike the situation in yeast and mammals, where copper deficiency results in a secondary iron deficiency, copper-deficient Chlamydomonas cells do not exhibit symptoms of iron deficiency. We propose the existence of a copper-independent iron assimilation pathway in this organism. PMID:12455693

La Fontaine, Sharon; Quinn, Jeanette M; Nakamoto, Stacie S; Page, M Dudley; Göhre, Vera; Moseley, Jeffrey L; Kropat, Janette; Merchant, Sabeeha

2002-10-01

37

Hyperfine field and hyperfine anomalies of copper impurities in iron  

SciTech Connect

A new value for the hyperfine magnetic field of copper impurities in iron is obtained by combining resonance frequencies from experiments involving {beta}-NMR on oriented nuclei on {sup 59}Cu, {sup 69}Cu, and {sup 71}Cu with magnetic moment values from collinear laser spectroscopy measurements on these isotopes. The resulting value, i.e., B{sub hf}(CuFe) = -21.794(10) T, is in agreement with the value adopted until now but is an order of magnitude more precise. It is consistent with predictions from ab initio calculations. Comparing the hyperfine field values obtained for the individual isotopes, the hyperfine anomalies in Fe were determined to be {sup 59{Delta}69}=0.15(9)% and {sup 71{Delta}69}=0.07(11)%.

Golovko, V. V.; Wauters, F.; Breitenfeldt, M.; De Leebeeck, V.; Roccia, S.; Soti, G.; Tandecki, M.; Traykov, E.; Van Gorp, S.; Severijns, N. [Instituut voor Kern- en Stralingsfysica, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Cottenier, S. [Center for Molecular Modeling, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Belgium); Zakoucky, D. [Nuclear Physics Institute, ASCR, CZ-250 68 Rez (Czech Republic)

2011-07-15

38

Hyperfine Field and Hyperfine Anomalies of Copper Impurities in Iron  

E-print Network

A new value for the hyperfine magnetic field of copper impurities in iron is obtained by combining resonance frequencies from experiments involving {\\beta}-NMR on oriented nuclei on 59-Cu, 69-Cu, and 71-Cu with magnetic moment values from collinear laser spectroscopy measurements on these isotopes. The resulting value, i.e., Bhf(CuFe) = -21.794(10) T, is in agreement with the value adopted until now but is an order of magnitude more precise. It is consistent with predictions from ab initio calculations. Comparing the hyperfine field values obtained for the individual isotopes, the hyperfine anomalies in Fe were determined to be 59{\\Delta}69=0.15(9)% and 71{\\Delta}69=0.07(11)%.

V. V. Golovko; F. Wauters; S. Cottenier; M. Breitenfeldt; V. De Leebeeck; S. Roccia; G. Soti; M. Tandecki; E. Traykov; S. Van Gorp; D. Zákoucký; N. Severijns

2011-07-29

39

Analysis of yttrium-barium-copper-oxide by x-ray diffraction and mechanical characterization  

SciTech Connect

The efforts in developing high-temperature superconductor (HTSC) YBa2Cu3O7 electrical leads are to benefit future NASA missions that will carry payloads with sensitive instruments operating at cryogenic temperatures. Present-day leads made of copper or magnesium are responsible for as much as 50 percent of the parasitic heat load on cryogenic systems. A reduction of this load could be achieved by replacing the conventional materials with HTSC ceramic electrical leads. Superconductor quality has become a concern in the industry, as has the development of effective evaluation methods. The factors that need to be examined for these materials include material purity, mechanical properties, and superconducting ability below the critical temperature. We applied several methods to study these factors: thermogravimetric analysis, x-ray diffraction, tensile testing, and laser-generated ultrasound. Our objectives were to determine the average tensile strength and Young's modulus of the HTSC material and to compare them to those values for copper and manganin.

Arsenovic, P.

1992-06-01

40

Analysis of Yttrium-Barium-Copper-Oxide by x ray diffraction and mechanical characterization  

NASA Technical Reports Server (NTRS)

The efforts in developing high-temperature superconductor (HTSC) YBa2Cu3O7 electrical leads are to benefit future NASA missions that will carry payloads with sensitive instruments operating at cryogenic temperatures. Present-day leads made of copper or magnesium are responsible for as much as 50 percent of the parasitic heat load on cryogenic systems. A reduction of this load could be achieved by replacing the conventional materials with HTSC ceramic electrical leads. Superconductor quality has become a concern in the industry, as has the development of effective evaluation methods. The factors that need to be examined for these materials include material purity, mechanical properties, and superconducting ability below the critical temperature. We applied several methods to study these factors: thermogravimetric analysis, x-ray diffraction, tensile testing, and laser-generated ultrasound. Our objectives were to determine the average tensile strength and Young's modulus of the HTSC material and to compare them to those values for copper and manganin.

Arsenovic, Petar

1992-01-01

41

The diverse roles of FRO family metalloreductases in iron and copper homeostasis.  

PubMed

Iron and copper are essential for plants and are important for the function of a number of protein complexes involved in photosynthesis and respiration. As the molecular mechanisms that control uptake, trafficking and storage of these nutrients emerge, the importance of metalloreductase-catalyzed reactions in iron and copper metabolism has become clear. This review focuses on the ferric reductase oxidase (FRO) family of metalloreductases in plants and highlights new insights into the roles of FRO family members in metal homeostasis. Arabidopsis FRO2 was first identified as the ferric chelate reductase that reduces ferric iron-chelates at the root surface-rhizosphere interface. The resulting ferrous iron is subsequently transported across the plasma membrane of root epidermal cells by the ferrous iron transporter, IRT1. Recent work has shown that two other members of the FRO family (FRO4 and FRO5) function redundantly to reduce copper to facilitate its uptake from the soil. In addition, FROs appear to play important roles in subcellular compartmentalization of iron as FRO7 is known to contribute to delivery of iron to chloroplasts while mitochondrial family members FRO3 and FRO8 are hypothesized to influence mitochondrial metal ion homeostasis. Finally, recent studies have underscored the importance of plasma membrane-localized ferric reductase activity in leaves for photosynthetic efficiency. Taken together, these studies highlight a number of diverse roles for FROs in both iron and copper metabolism in plants. PMID:24711810

Jain, Anshika; Wilson, Grandon T; Connolly, Erin L

2014-01-01

42

Magnetic and magnetorheological properties of flowable compositions based on barium and strontium ferrites and iron oxides  

NASA Astrophysics Data System (ADS)

Magnetic and magnetorheological properties of a number of compositions are examined. The compositions are based on barium and strontium ferrites, magnetite, and (gamma) -Fe2O3, both commercial and synthesized using specially developed methods, suspended in transformer oil and synthetic binders based on phenol-formaldehyde, epoxyacrylic and pentaphthalic resins. The influence of numerous factors, such as the type and magnetic properties of the filler, types of the binder, magnetic properties of the composition on the orientational effect of the filler in a magnetic field was evaluated. The latter was judged by a magnitude of magnetorheological effect.

Lazareva, Tatjana G.; Shitik, Ilia G.

1997-02-01

43

Superconducting Properties of Epitaxial Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA) Thin Films and Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA)/PRASEODYMIUM BARIUM(2) COPPER(3) OXYGEN(7-Z)/YTTRIUM BARIUM(2) COPPER(3) OXYGEN(7 - Heterostructures Grown by Pulsed Laser Deposition  

NASA Astrophysics Data System (ADS)

The study of the intrinsic behavior of high transition temperature copper-oxide superconductors (HTSC) has proven to be challenging because of the extreme sensitivity of their transport properties on material quality. These compounds are characterized by a high degree of structural and electrical anisotropy, and a very short superconductive coherence length of the same order as the size of the crystalline unit cell (~5-30 A). As a result, microscopic defects such as oxygen vacancies, cationic disorder, and the presence of minute impurities have a significant effect on electrical transport in these materials. Therefore, much effort has been expended in synthesizing sizable samples that are homogeneous, well characterized, and emenable to the study of the anisotropic properties of the HTSC. We have demonstrated that thin films of HTSC compounds such as rm YBa_2Cu_3O_{7 -delta}, which is a 92 K superconductor, can be synthesized easily by a technique known as pulsed laser deposition, and display superconducting properties comparable to or better than those of bulk poly- or single -crystalline samples. Furthermore, we have shown that layer by layer film growth permits unprecedented control on the characteristics of the sample allowing precise artificial adjustment of sample, properties on the scale of one or two unit cells; for example, we have epitaxially grown rm YBa_2Cu_3O_{7-delta}/PrBa _2Cu_3O_{7-z}/YBa_ 2Cu_3O_{7-delta} heterostructures (where rm PrBa_2Cu _3O_{7-z} is a non-superconducting isomorph of rm YBa_2Cu_3O_ {7-delta}) with individual layer thicknesses of a few tens of angstroms. We have applied such artificially structured systems to the fabrication of Josephson weak-links, and have successfully and reproducibly observed both the dc and ac Josephson effects in these junctions. We have also demonstrated thin films grown with the perovskite copper-oxide planes oriented perpendicular to the film surface. In such films, the current carrying copper-oxide planes of the superconductor are not continuous but are arranged in a mosaic, allowing for the simultaneous flow of superconducting currents along the in-plane and out-of-plane directions of the film. On a scale > 1 mum, this results in a quasi -isotropic superconducting microstructure, and is a demonstration of the enormous potential that superconducting thin film heterostructures offer for investigating the phenomenon of high temperature superconductivity.

Inam, Arun

44

Impairment of Interrelated Iron- and Copper Homeostatic Mechanisms in Brain Contributes to the Pathogenesis of Neurodegenerative Disorders  

PubMed Central

Iron and copper are important co-factors for a number of enzymes in the brain, including enzymes involved in neurotransmitter synthesis and myelin formation. Both shortage and an excess of iron or copper will affect the brain. The transport of iron and copper into the brain from the circulation is strictly regulated, and concordantly protective barriers, i.e., the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) barrier (BCB) have evolved to separate the brain environment from the circulation. The uptake mechanisms of the two metals interact. Both iron deficiency and overload lead to altered copper homeostasis in the brain. Similarly, changes in dietary copper affect the brain iron homeostasis. Moreover, the uptake routes of iron and copper overlap each other which affect the interplay between the concentrations of the two metals in the brain. The divalent metal transporter-1 (DMT1) is involved in the uptake of both iron and copper. Furthermore, copper is an essential co-factor in numerous proteins that are vital for iron homeostasis and affects the binding of iron-response proteins to iron-response elements in the mRNA of the transferrin receptor, DMT1, and ferroportin, all highly involved in iron transport. Iron and copper are mainly taken up at the BBB, but the BCB also plays a vital role in the homeostasis of the two metals, in terms of sequestering, uptake, and efflux of iron and copper from the brain. Inside the brain, iron and copper are taken up by neurons and glia cells that express various transporters. PMID:23055972

Skj?rringe, Tina; M?ller, Lisbeth Birk; Moos, Torben

2012-01-01

45

Influence of indigenous and added iron on copper extraction from soil.  

PubMed

Experimental tests of copper leaching from a low permeability soil are presented and discussed. The objective of the experiments was to investigate the influence of indigenous and added iron in the soil towards copper mobilization. Metals' leaching was performed by flushing (column tests) or washing (batch tests) the soil with an aqueous solution of ethylenediaminetetraacetic acid, EDTA. An excess of EDTA was used in flushing tests (up to a EDTA:Cu molar ratio of about 26.2:1), while, in washing tests, the investigated EDTA vs. copper molar ratios were in the range between 1 (equimolar tests) and 8. Copper extraction yield in flushing tests (up to about 85%) was found to depend upon contact time between the soil and the leaching solution and the characteristics of the conditioning solution. The saturation of the soil with a NaNO(3) solution before the treatment, favoured the flushing process reducing the time of percolation, but resulted in a lower metal extraction during the following percolation of EDTA. The indigenous iron was competitive with copper to form EDTA complexes only when it was present in the organic and oxides-hydroxides fractions. Artificial iron addition to the soil resulted in an increase of both the exchangeable iron and the iron bonded to the organic fraction of the soil, thus increasing the overall amount of iron available to extraction. In both batch and continuous tests, the mechanism of copper extraction was found to involve the former dissolution of metal salts, that lead to an initial high concentration of both copper and selected competitive cations (essentially Ca(2+)), and the following EDTA exchange reaction between calcium and copper complexes. The initial metal salts dissolution was found to be pH-dependant. PMID:19477586

Di Palma, Luca

2009-10-15

46

Grain refinement of copper by the addition of iron and by electromagnetic stirring  

NASA Astrophysics Data System (ADS)

The effect of iron additions in the range of 0.57 to 7.5 wt pet on the grain size of electromagnetically levitated copper-iron alloys was investigated. The samples were solidified while levitated or quenched in water from the molten state. The addition of iron was found to be effective in reducing the grain size of copper, and the average grain size decreased as the iron content was increased up to the peritectic liquid composition of about 2.8 wt pet Fe. Beyond this composition, the grain size of the samples solidified in the levitated state was insensitive to the iron content, whereas that of the quenched samples continuously decreased with increasing iron content. The results indicate that electromagnetic stirring causes fragmentation of copper dendrites in the hypoperitectic region, and hence enhances grain refinement. In the hyperperitectic region, on the other hand, the stirring has a detrimental effect on the grain refinement by agglomerating the primary iron particles which act as heterogeneous nucleation sites for the copper matrix.

Patchett, J. A.; Abbaschian, G. J.

1985-09-01

47

Iron, copper and zinc isotopic fractionation up mammal trophic chains  

NASA Astrophysics Data System (ADS)

There is a growing body of evidence that some non-traditional elements exhibit stable isotope compositions that are distinct in botanical and animal products, providing potential new tracers for diet reconstructions. Here, we present data for iron (Fe), copper (Cu) and zinc (Zn) stable isotope compositions in plants and bones of herbivores and carnivores. The samples come from trophic chains located in the Western Cape area and in the Kruger National Park in South Africa. The Fe, Cu and Zn isotope systematics are similar in both parks. However, local Cu, and possibly Zn, isotopic values of soils influence that of plants and of higher trophic levels. Between plants and bones of herbivores, the Zn isotope compositions are 66Zn-enriched by about 0.8‰ whereas no significant trophic enrichment is observed for Fe and Cu. Between bones of herbivores and bones of carnivores, the Fe isotope compositions are 56Fe-depleted by about 0.6‰, the Cu isotope compositions are 65Cu-enriched by about 1.0‰, and the Zn isotope compositions are slightly 66Zn-depleted by about 0.2‰. The isotopic distributions of the metals in the body partly explain the observed trophic isotopic systematics. However, it is also necessary to invoke differential intestinal metal absorption between herbivores and carnivores to account for the observed results. Further studies are necessary to fully understand how the Fe, Cu and Zn isotope values are regulated within the ecosystem's trophic levels, but the data already suggests significant potential as new paleodietary and paleoecological proxies.

Jaouen, Klervia; Pons, Marie-Laure; Balter, Vincent

2013-07-01

48

Flux Pinning Phenomena in Electron Irradiated Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA) Single Crystals  

NASA Astrophysics Data System (ADS)

It has been shown that 1 MeV electron irradiation to a typical dose Phi~ 1times 10^{19} cm^{ -2} results in an enhancement of the critical current density in twinned and untwinned YBa_2 Cu_3O_{7 -delta} single crystals. Values up to two times the preirradiation J_{c} at 10 K and 1 T are observed. The J _{c} enhancement is accompanied by a dramatic increase of the irreversibility field. A threshold incident electron energy (E_{ t}~ 0.5 MeV) is found above which flux pinning enhancement is observed. The data indicated that the electron radiation-induced defects are effective pinning centers only for the orientation H parallel c-axis. In-situ TEM studies in the HVEM suggest that the pinning centers must be smaller than 20 A. A comparison of the electron irradiation results with those of proton irradiation experiments indicate a lower magnitude of enhancement of J_{c} at 10 K and 2 T for the electron case. The probable explanation is the difference in the energy spectra of the PKAs produced by the two types of irradiation. GdBa_2Cu_3O_{7-delta } and EuBa_2Cu_3O _{7-delta} single crystals irradiated with 0.6 MeV electrons displayed similar flux pinning enhancements as YBa_2Cu _3O_{7-delta} crystals, indicating that Y displacements are not primary flux pinners. The evidence from annealing studies suggests that the primary pinning center produced by the electron irradiation is not associated with the oxygen in the Cu-O chains. Instead, a consistent interpretation of the data suggests that the primary pinning defect is most likely based on the displacement of a copper atom from the CuO_2 plane. In order to account for the complete enhancement of J_{c} other pinning mechanisms aside from point defects, such as small point defect clusters, should be considered.

Giapintzakis, John Konstantinos

1992-01-01

49

Evolution of Microstructures During Austempering of Ductile Irons Alloyed with Manganese and Copper  

NASA Astrophysics Data System (ADS)

The influences of relatively high manganese (0.45 through 1.0 wt pct) and copper (0.56 through 1.13 wt pct) contents on microstructure development and phase transformation in three austempered ductile irons have been studied. The experimental ductile irons alloyed with copper and manganese are found to be practically free from intercellular manganese segregation. This suggests that the positive segregation of manganese is largely neutralized by the negative segregation of copper when these alloying elements are added in appropriate proportions. The drop in unreacted austenite volume (UAV) with increasing austempering temperature and time is quite significant in irons alloyed with copper and manganese. The ausferrite morphology also undergoes a transition from lenticular to feathery appearance of increasing coarseness with the increasing austempering temperature and time. SEM micrographs of the austempered samples from the base alloy containing manganese only, as well as copper plus manganese-alloyed irons, clearly reveal the presence of some martensite along with retained austenite and ferrite. X-ray diffraction analysis also confirms the presence of these phases. SEM examination further reveals the presence of twinned martensite in the copper plus manganese-alloyed samples. The possibility of strain-induced transformation of austenite to martensite during austempering heat treatment is suggested.

Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar

2013-03-01

50

Urinary excretion of copper, zinc and iron with and without D-penicillamine administration in relation to hepatic copper concentration in dogs.  

PubMed

Hereditary copper-associated hepatitis in dogs resembles Wilson's disease, a copper storage disease in humans. Values for urinary copper excretion are well established in the diagnostic protocol of Wilson's disease, whereas in dogs these have not been evaluated. The objectives of this study were to characterize both basal and D-penicillamine induced urinary copper, zinc and iron excretion in dogs in relation to hepatic copper concentration. Beagles, Beagle-Bedlington terrier cross-breeds homozygous for the COMMD1 gene mutation that causes copper toxicosis, and Labrador retrievers with normal or increased hepatic copper concentrations were investigated. The hepatic copper phenotype was determined by histological evaluation of liver biopsies and measurement of the hepatic copper concentration by instrumental neutron activation analysis. Urinary excretion of copper, iron and zinc was measured via inductively coupled plasma optical emission spectrometry under basal conditions and after oral administration of a single dose (20mg/kg bodyweight) of the chelator D-penicillamine. There was a rapid increase in urinary excretion of copper and zinc, but not iron after D-penicillamine administration. This increase was not different between dogs with high or normal hepatic copper concentrations. D-penicillamine-induced urinary copper excretion and the copper/creatinine ratio did not correlate with hepatic copper concentrations in the dogs studied, although basal urinary copper/zinc ratios did correlate with hepatic copper concentrations in Labrador retrievers. The latter parameter may be useful in diagnostic and follow-up protocols for copper-associated hepatitis in Labrador retrievers. PMID:23583003

Fieten, H; Hugen, S; van den Ingh, T S G A M; Hendriks, W H; Vernooij, J C M; Bode, P; Watson, A L; Leegwater, P A J; Rothuizen, J

2013-08-01

51

Some new chromogens for iron, cobalt, and copper Substituted hydrazidines and 1,2,4-triazines containing the ferroin group.  

PubMed

The spectral characteristics and solution conditions requisite for formation of the iron(II), cobalt(II), and copper(I) complexes of some newly synthesised compounds containing the ferroin functional grouping have been determined. These properties are useful for evaluation of the possible analytical effectiveness of the compounds as spectrophotometric reagents for the determination of iron, cobalt, and copper. PMID:18959951

Schilt, A A

1966-07-01

52

77 FR 36980 - Migratory Bird Hunting; Application for Approval of Copper-Clad Iron Shot as Nontoxic for...  

Federal Register 2010, 2011, 2012, 2013

...FF09M21200-123-FXMB1231099BPP0L2] RIN 1018-AY61 Migratory Bird Hunting; Application for Approval of Copper-Clad Iron Shot as Nontoxic for Waterfowl Hunting AGENCY: Fish and Wildlife Service, Interior...copper and iron as nontoxic for waterfowl hunting in the United States. The shot...

2012-06-20

53

Phormidium autumnale Growth and Anatoxin-a Production under Iron and Copper Stress  

PubMed Central

Studies on planktonic cyanobacteria have shown variability in cyanotoxin production, in response to changes in growth phase and environmental factors. Few studies have investigated cyanotoxin regulation in benthic mat-forming species, despite increasing reports on poisoning events caused by ingestion of these organisms. In this study, a method was developed to investigate changes in cyanotoxin quota in liquid cultures of benthic mat-forming cyanobacteria. Iron and copper are important in cellular processes and are well known to affect growth and selected metabolite production in cyanobacteria and algae. The effect of iron (40–4000 ?g L?1) and copper (2.5–250 ?g L?1) on growth and anatoxin-a quota in Phormidium autumnale was investigated in batch culture. These concentrations were chosen to span those found in freshwater, as well as those previously reported to be toxic to cyanobacteria. Anatoxin-a concentrations varied throughout the growth curve, with a maximum quota of between 0.49 and 0.55 pg cell?1 measured within the first two weeks of growth. Growth rates were significantly affected by copper and iron concentrations (P < 0.0001); however, no statistically significant difference between anatoxin-a quota maxima was observed. When the iron concentrations were 800 and 4000 ?g L?1, the P. autumnale cultures did not firmly attach to the substratum. At 250 ?g L?1 copper or either 40 or 4000 ?g L?1 iron, growth was suppressed. PMID:24351714

Harland, Francine M. J.; Wood, Susanna A.; Moltchanova, Elena; Williamson, Wendy M.; Gaw, Sally

2013-01-01

54

Studies of Pure and Iron Doped Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA)  

NASA Astrophysics Data System (ADS)

YBa_2(Cu_ {1-x}Fe_{ x})O_{7-delta } (YBCO) compounds for x = 0.0, 0.01, 0.02, 0.05, 0.15, and 0.25 were studied. Samples include fully oxygenated virgin, and oxygen deficient samples, and the oxygen deficient samples after reoxygenation. X-ray diffraction, oxygen content, and magnetization measurements were used for obtaining information respectively on crystal structure, oxygen stoichiometry, and superconducting (SC) critical temperature (T_{c}). By isothermal vacuum annealing (VA) pure (x = 0) YBCO superconducting samples in the temperature range 300-800C, some important results such as: (1) the steplike increase of c axis length, and (2) the familiar plateaus in T_{c} with oxygen stoichiometry were reproduced. For x = 0.02-0.05, the symmetry of crystal changed from orthorhombic to tetragonal, and for x = 0.25, sample became non SC. We find evidence that the Fe-O bonds in YBCO are stronger than the Cu-O bonds. Mossbauer studies of Fe doped virgin samples; by VA these virgin samples at 800C; and reoxygenating these oxygen desorbed samples at 410C were used for identifying Fe sites, and for determining oxygen coordination of Fe. Only three quadrupole doublets each corresponding to an Fe site were sufficient to fit room temperature (RT) Mossbauer spectra of virgin samples for x <= 0.15, while for x = 0.25, two additional magnetic sextets had to be added. The subspectra are explained in terms of square planar, pseudotetrahedral, and octahedral oxygen environment around Fe atoms in the crystal. Due to vacuum annealing samples at T_{a } >= 400C, new Fe sites appeared in all RT spectra, and depending on the value of x, and the annealing temperature, T_{a}, one or two magnetic sites evolved. From the Mossbauer spectra of virgin (x = 0.25 only), and oxygen deficient samples as a function of temperature we determined the magnetic ordering temperature, T_{ N}. The values of T_ {N} are 394K for the 25% virgin, and from 419-472K for the 2-25% samples vacuum annealed at 800C for 2.5 hours. The increase of T_ {N} with Fe concentration is believed to be due to increasing preferential alignment of Fe moments as the value of x increases.

Siddique, Rezaul K.

55

Novel lead-free piezoelectric ceramics in the solid solution (1-x) bismuth iron oxide-barium titanate  

NASA Astrophysics Data System (ADS)

Piezoelectric materials are widely used in many areas of science and technology due to their electromechanical properties. The transformation of mechanical energy into electrical signals and vice versa based on the piezoelectric effect has led to the development of sensor devices and piezoelectric actuators used in accelerometers, pressure and vibration meters, micropositioning devices, ultrasound generators, motors etc. The most technologically important piezoelectric material is lead zirconate titanate PbZrO3-PbTiO3 (PZT), however, the commercial manufacture and application of PZT as a lead-based material represent serious health hazards. The need to reduce environmental contamination by lead-based substances has created the current drive to develop alternative lead-free piezoelectric materials. The present work describes a detailed investigation of the novel multifunctional ceramic material in a solid solution of bismuth iron oxide and barium titanate (1-x)BiFeO 3-xBaTiO3 (BFBT) with an emphasis on the room temperature piezoelectric properties and structural study. BFBT ceramics were prepared via the metal oxide solid-state preparation route. Addition of manganese oxide MnO2 increased the DC resistance by one to five orders of magnitude allowing high-field poling and piezoelectric strain measurements in Mn-modified BFBT ceramics. Piezoelectric d33 coefficients of 116 pC/N (low-field, Berlincourt) and 326 pC/N (effective, high-field) are reported for the compositions with x=0.25 and 0.33 respectively. Piezoelectric measurements using the Rayleigh law under applied large DC electric field indicated an increased low-field piezoelectric d33 coefficient to 150 pC/N (x=0.33). The DC bias is believed to stabilize the ferroclectric domain structure leading to stronger intrinsic and extrinsic contributions to the piezoelectric response in BFBT. Bright field TEM imaging confirmed formation of macroscopic domains following high field poling from initially frustrated domain state indicating the ability to induce long-range polarization order in BFBT ceramics. It is believed that the results of this work will contribute to the development of a family of lead-free piezoelectric materials based on BiFeO3-BaTiO3 system. KEYWORDS: Bismuth ferrite, Barium titanate, Lead-free, Piezoelectric ceramics, Crystal Structure

Leontsev, Serhiy

56

Strength and elasticity of iron and copper at high shock-wave compression pressures  

Microsoft Academic Search

The elastic and strength parameters of iron and copper were determined experimentally at high shock-wave compression pressures of 1–2 Mbar. The attenuation of shock waves created by the impact of thin plates in blocks of the investigated materials was recorded in the experiments. The Poisson ratios, bulk moduli, shear moduli, and yield strength Y for iron at 1.11 and 1.85

L. V. Al'tshuler; M. I. Brazhnik; G. S. Telegin

1971-01-01

57

Rates of dissolution of rotating iron cylinders in liquid copper and cu-fe alloys  

Microsoft Academic Search

Iron cylinders with molybdenum capped ends are rotated at speeds of 260, 570, and 835 rpm in liquid copper and Cu-Fe alloys\\u000a maintained at 1220?, 1300?C, and 1370?C under argon at 1 atm pressure. The dependence of the dissolution rate of the cylinders\\u000a on the concentration of iron in the bulk liquid is observed. The solution-rate constants defined by an

R. Ohno

1973-01-01

58

Effects of mine drainage on the river hayle, cornwall a) factors affecting concentrations of copper, zinc and iron in water, sediments and dominant invertebrate fauna  

Microsoft Academic Search

Concentrations of copper, zinc and iron were measured in waters, sediments and invertebrates collected from the River Hayle. In river water at least 70% of copper and iron was associated with the ‘particulate’ fraction whereas 80% of zinc was in the ‘soluble’ form. Although total concentrations of zinc in water exceeded those of copper approximately ten fold, copper predominated over

Barbara E. Brown

1977-01-01

59

Effects of Copper and Austempering on Corrosion Behavior of Ductile Iron in 3.5 Pct Sodium Chloride  

NASA Astrophysics Data System (ADS)

Although alloying and heat treatments are common industrial practices to obtain ductile irons with desired mechanical properties, related information on how the two practices affect corrosion behavior is scarce. In this study, two ductile irons—with and without 1 wt pct copper addition—were austempered to obtain austempered ductile irons (ADIs). Polarization tests and salt spray tests were conducted to explore how both copper-alloying and austempering heat treatments influenced the corrosion behavior of ductile irons. The results showed that the corrosion resistance of 1 wt pct copper-alloyed ductile iron was better than that of the unalloyed one, while ADI had improved corrosion resistance compared with the as-cast. In particular, the ductile iron combined with the copper-alloying and austempering treatments increased the corrosion inhibition efficiency up to 84 pct as tested in 3.5 wt pct NaCl solution.

Hsu, Cheng-Hsun; Lin, Kuan-Ting

2013-10-01

60

Integration of nonlinear dielectric barium strontium titanate with polycrystalline yttrium iron garnet  

NASA Astrophysics Data System (ADS)

Biaxially oriented nonlinear dielectric Ba0.6Sr0.4TiO3 (BST) films have been grown on polycrystalline ferrite yttrium iron garnet (YIG) substrates. We use a structurally and chemically compatible MgO buffer to improve the crystallinity of the BST on polycrystalline YIG substrates, where the biaxially oriented MgO is deposited by an ion-beam assisted-deposition technique. The biaxially oriented BST has a dielectric loss of less than 0.01 and a capacitance tunability of greater than 25% at a direct current bias voltage of 40 V at room temperature.

Jia, Q. X.; Groves, J. R.; Arendt, P.; Fan, Y.; Findikoglu, A. T.; Foltyn, S. R.; Jiang, H.; Miranda, F. A.

1999-03-01

61

Lenticular nucleus hyperechogenicity in Wilson's disease reflects local copper, but not iron accumulation.  

PubMed

In patients with Wilson's disease (WD) transcranial brain sonography typically reveals areas of increased echogenicity (hyperechogenicity) of the lenticular nucleus (LN). Correlation with T2-hypointensity on magnetic resonance images suggested that LN hyperechogenicity in WD is caused by trace metal accumulation. Accumulation of both, copper and iron, in the brain of WD patients has been reported. The present study was designed to elucidate whether LN hyperechogenicity in WD reflects accumulation of copper or iron. Post-mortem brains of 15 WD patients and one non-WD subject were studied with ultrasonography in an investigator-blinded fashion. LN hyperechogenicity was measured planimetrically by manual tracing as well as using digitized image analysis. The putaminal copper content was determined in samples of 11 WD brains and the non-WD brains using inductively coupled plasma mass spectrometry, and iron content was assessed using flame atomic absorption spectroscopy. LN was normal on ultrasonography only in the non-WD brain, but abnormal (hyperechogenic) in all WD brains. Digitized image analysis measures of LN hyperechogenicity and, by trend, manual measures correlated with putaminal copper content (Pearson test; digitized: r = 0.77, p = 0.04; manual: r = 0.57, p = 0.051) but not with iron content (each, p > 0.18). LN hyperechogenicity measures were unrelated to age at death of patients, age at onset of WD, WD duration, age of brain specimen, serum copper or serum ceruloplasmin (each, p > 0.1). We conclude that LN hyperechogenicity in WD reflects copper, but not iron accumulation. Further studies are warranted to elucidate the use of transcranial brain sonography for monitoring therapeutic effects of chelating agents in WD patients. PMID:24615184

Walter, Uwe; Skowro?ska, Marta; Litwin, Tomasz; Szpak, Gra?yna Maria; Jab?onka-Salach, Katarzyna; Skoloudík, David; Bulska, Ewa; Cz?onkowska, Anna

2014-10-01

62

Metal passivity as mechanism of metal carcinogenesis: Chromium, nickel, iron, copper, cobalt, platinum, molybdenum  

Microsoft Academic Search

For the transition metals chromium, nickel, iron, copper, cobalt, platinum, and molybdenum, mechanisms of stable bonding in biochemistry (emphasis on carcinogenic mechanisms), chemistry, industrial chemistry, as well as epidemiological, occupational, orthopedic (implant devices) effects related to carcinogenesis, were reviewed. Hypothetically, the propensity to stable bonding (inertness), which ensures the metals’ performance capacity for consumers and industrial application, relates to their

Cornelia Richardson-Boedler

2007-01-01

63

Influence of vegetative cycle of asparagus ( Asparagus officinalis L.) on copper, iron, zinc and manganese content  

Microsoft Academic Search

The essential elements copper (Cu), iron (Fe), zinc (Zn) and manganese (Mn) were analyzed in fresh asparagus to determine the effects of the vegetative cycle of the plant on the micronutrient content. Asparagus samples were classified in two groups by diameter (14 mm). Asparagus from a sample group with the same diameter were divided into two portions (apical and basal)

M. A. Amaro-Lopez; G. Zurera-Cosano; R. Moreno-Rojas; R. M. Garcia-Gimeno

1995-01-01

64

The effect of iron and copper impurities on the wettability of sphalerite (110) surface.  

PubMed

The effect of impurities in the zinc sulfide mineral sphalerite on surface wettability has been investigated theoretically to shed light on previously reported conflicting results on sphalerite flotation. The effect of iron and copper impurities on the sphalerite (110) surface energy and on the water adsorption energy was calculated with the semi-empirical method modified symmetrically orthogonalized intermediate neglect of differential overlap (MSINDO) using the cyclic cluster model. The effect of impurities or dopants on surface energies is small but significant. The surface energy increases with increasing surface iron concentration while the opposite effect is reported for increasing copper concentration. The effect on adsorption energies is much more pronounced with water clearly preferring to adsorb on an iron site followed by a zinc site, and copper site least favorable. The theoretical results indicate that a sphalerite (110) surface containing iron is more hydrophilic than the undoped zinc sulfide surface. In agreement with the literature, the surface containing copper (either naturally or by activation) is more hydrophobic than the undoped surface. PMID:21462368

Simpson, Darren J; Bredow, Thomas; Chandra, Anand P; Cavallaro, Giuseppe P; Gerson, Andrea R

2011-07-15

65

MD description of damage production in displacement cascades in copper and ?-iron.  

SciTech Connect

Molecular dynamics computer simulation was applied for an extensive study of primary damage creation in displacement cascades in copper and {alpha}-iron. Primary knock-on atom energy, E{sub p}, of up to 25 keV in copper and 100 keV in iron was considered for irradiation temperatures in the range 100-900 K. Special attention was paid to comprehensive statistical treatment of the number and type of defects created in cascades by conducting multiple simulations for each value of energy and temperature. The total number of point defects per cascade is significantly lower than that predicted by the NRT model and rather similar in the two metals. The fraction of self-interstitial atoms (SIAs) and vacancies that agglomerate in clusters in the cascade process was analysed in detail. The clustered fraction of SIAs increases with temperature increase and is larger in copper than iron. SIA clusters have a variety of forms in both metals and, although most are glissile clusters of parallel crowdions, a significant fraction are sessile. The latter include Frank dislocation loops in copper. Tightly packed arrangements of vacancies do not form in iron, and so the fraction of clustered vacancies depends strongly on the range within which point defects are defined to be near-neighbours. Arrangements of vacancies in first-neighbour sites are common in copper. Most are irregular stacking fault tetrahedra (SFTs). In 53 simulations of cascades with E{sub p} = 25 keV at 100 K, the largest cluster formed contained 89 vacancies. The size spectrum of SFT-like clusters is similar to that found experimentally in neutron-irradiated copper, suggesting that the SFTs observed in experiment are formed directly in the cascade process.

Bacon, David J [University of Liverpool; Osetskiy, Yury N [ORNL; Stoller, Roger E [ORNL; Voskoboinikov, Roman E [University of Liverpool

2003-01-01

66

MD description of damage production in displacement cascades in copper and ?-iron  

NASA Astrophysics Data System (ADS)

Molecular dynamics computer simulation was applied for an extensive study of primary damage creation in displacement cascades in copper and ?-iron. Primary knock-on atom energy, Ep, of up to 25 keV in copper and 100 keV in iron was considered for irradiation temperatures in the range 100-900 K. Special attention was paid to comprehensive statistical treatment of the number and type of defects created in cascades by conducting multiple simulations for each value of energy and temperature. The total number of point defects per cascade is significantly lower than that predicted by the NRT model and rather similar in the two metals. The fraction of self-interstitial atoms (SIAs) and vacancies that agglomerate in clusters in the cascade process was analysed in detail. The clustered fraction of SIAs increases with temperature increase and is larger in copper than iron. SIA clusters have a variety of forms in both metals and, although most are glissile clusters of parallel crowdions, a significant fraction are sessile. The latter include Frank dislocation loops in copper. Tightly packed arrangements of vacancies do not form in iron, and so the fraction of clustered vacancies depends strongly on the range within which point defects are defined to be near-neighbours. Arrangements of vacancies in first-neighbour sites are common in copper. Most are irregular stacking fault tetrahedra (SFTs). In 53 simulations of cascades with Ep=25 keV at 100 K, the largest cluster formed contained 89 vacancies. The size spectrum of SFT-like clusters is similar to that found experimentally in neutron-irradiated copper, suggesting that the SFTs observed in experiment are formed directly in the cascade process.

Bacon, D. J.; Osetsky, Yu. N.; Stoller, R.; Voskoboinikov, R. E.

2003-12-01

67

Computational Benchmarking in Biomimetic Nickel, Copper, and Iron Complexes  

E-print Network

in the absence of experimental data. In this dissertation, such techniques serve to elucidate the observed reactivity or electronic character of both nickel and copper bound in square planar N?S? ligand fields, and of {Fe(NO)?} units, respectively. Nickel...

Brothers, Scott Michael

2012-02-14

68

Zinc Pyrithione Inhibits Yeast Growth through Copper Influx and Inactivation of Iron-Sulfur Proteins?†  

PubMed Central

Zinc pyrithione (ZPT) is an antimicrobial material with widespread use in antidandruff shampoos and antifouling paints. Despite decades of commercial use, there is little understanding of its antimicrobial mechanism of action. We used a combination of genome-wide approaches (yeast deletion mutants and microarrays) and traditional methods (gene constructs and atomic emission) to characterize the activity of ZPT against a model yeast, Saccharomyces cerevisiae. ZPT acts through an increase in cellular copper levels that leads to loss of activity of iron-sulfur cluster-containing proteins. ZPT was also found to mediate growth inhibition through an increase in copper in the scalp fungus Malassezia globosa. A model is presented in which pyrithione acts as a copper ionophore, enabling copper to enter cells and distribute across intracellular membranes. This is the first report of a metal-ligand complex that inhibits fungal growth by increasing the cellular level of a different metal. PMID:21947398

Reeder, Nancy L.; Kaplan, Jerry; Xu, Jun; Youngquist, R. Scott; Wallace, Jared; Hu, Ping; Juhlin, Kenton D.; Schwartz, James R.; Grant, Raymond A.; Fieno, Angela; Nemeth, Suzanne; Reichling, Tim; Tiesman, Jay P.; Mills, Tim; Steinke, Mark; Wang, Shuo L.; Saunders, Charles W.

2011-01-01

69

Zinc pyrithione inhibits yeast growth through copper influx and inactivation of iron-sulfur proteins.  

PubMed

Zinc pyrithione (ZPT) is an antimicrobial material with widespread use in antidandruff shampoos and antifouling paints. Despite decades of commercial use, there is little understanding of its antimicrobial mechanism of action. We used a combination of genome-wide approaches (yeast deletion mutants and microarrays) and traditional methods (gene constructs and atomic emission) to characterize the activity of ZPT against a model yeast, Saccharomyces cerevisiae. ZPT acts through an increase in cellular copper levels that leads to loss of activity of iron-sulfur cluster-containing proteins. ZPT was also found to mediate growth inhibition through an increase in copper in the scalp fungus Malassezia globosa. A model is presented in which pyrithione acts as a copper ionophore, enabling copper to enter cells and distribute across intracellular membranes. This is the first report of a metal-ligand complex that inhibits fungal growth by increasing the cellular level of a different metal. PMID:21947398

Reeder, Nancy L; Kaplan, Jerry; Xu, Jun; Youngquist, R Scott; Wallace, Jared; Hu, Ping; Juhlin, Kenton D; Schwartz, James R; Grant, Raymond A; Fieno, Angela; Nemeth, Suzanne; Reichling, Tim; Tiesman, Jay P; Mills, Tim; Steinke, Mark; Wang, Shuo L; Saunders, Charles W

2011-12-01

70

Effects of dietary copper, cadmium, iron, molybdenum and manganese on selenium utilization by the rat  

SciTech Connect

The possible antagonistic effects of different dietary concentrations of copper (1.3-200 mg/kg), cadmium (1-5 mg/kg), iron (20-500 mg/kg), molybdenum (0.3-50 mg/kg) and manganese (0.2-200 mg/kg) on selenium utilization by the rat were studied by the measurement of the absorption and organ distribution of dietary selenium as (75Se)selenite and by effects on organ glutathione peroxidase (GSH-Px: EC 1.11.1.9) activity. Although a high concentration of copper (200 mg/kg) in the diet did not alter the percentage absorption and total-body retention of doses of 75SeO3(2)- by rats, after such treatment tissue 75Se distribution was changed and was lower total selenium in some tissues. After copper treatment (200 mg/kg diet) GSH-Px activity of liver, testis, kidney and whole blood was also lower. Dietary cadmium, iron, molybdenum and manganese at the concentrations investigated had no significant effects on selenium metabolism. Thus it is unlikely that copper, cadmium, iron, molybdenum and manganese at normal dietary concentrations will have a major effect on selenium metabolism in the rat, especially if adequate amounts of selenium are being consumed.

Abdel Rahim, A.G.; Arthur, J.R.; Mills, C.F.

1986-03-01

71

Summary of ENDF/B-V evaluations for carbon, calcium, iron, copper, and lead and ENDF/B-V Revision 2 for calcium and iron  

SciTech Connect

This report, together with documents already published, describes the ENDF/B-V evaluations of the neutron and gamma-ray-production cross sections for carbon, calcium, iron, copper, and lead and the ENDF/B-V Revision 2 evaluations for calcium and iron.

Fu, C Y

1982-09-01

72

Iron release from transferrin induced by mixed ligand complexes of copper(II).  

PubMed

Copper(II) complexes CuL1L2 with the ligand pairs 3-phosphoglycerate (PG)/ethylenediamine (en), phosphoserine (PS)/ethylenediamine, phosphoserine/malonate (mal) are shown to be effective in inducing the release of both iron atoms from di-ferric transferrin (Fe2Tf; human serum transferrin) at pH 7.3 in 1 M NaCl at 25 degrees C. Half-times of the reaction with Cu(PG)(en)- were less than 1 min at 0.02 M concentration. The iron(III) products are polynuclear hydroxo complexes. There is weaker interaction with Cu(PS)4-2 and virtually none with Cu(serine)(en) nor Cu(PS)(2,2'-bipyridyl)-, revealing crucial effects of the combined ligand sphere including the phosphomonoester group. The results suggest that the release of iron from Fe2Tf, or from either monoferric transferrins, occurred due to the breakdown of the stability of iron binding in conjunction with the expulsion of the synergistic anion carbonate (or oxalate). The active copper(II) complexes are postulated to be models of membrane components that could liberate iron from transferrin succeeding its uptake at the receptor sites of cells. PMID:2490073

Glaus, M; Schneider, W

1989-01-01

73

Kinetics and deposit morphology of gold cemented on magnesium, aluminum, zinc, iron and copper from ammonium thiosulfate–ammonia solutions  

Microsoft Academic Search

The kinetics of gold cementation by magnesium aluminum, zinc, iron and copper at equal conditions as well as the morphology of cementation products and the dissolution of cementing agents were investigated. Both the effect of cementing agents on gold cementation rate and the dissolution of metals decrease in order Cu>Zn>Mg>Fe>Al. High dissolution of magnesium, zinc, iron and copper per mol

M. Karavasteva

2010-01-01

74

The effects of oral contraceptive use on iron and copper concentrations in breast milk  

Microsoft Academic Search

Objective: To determine the effects of oral contraceptive (OC) treatment on maternal iron and copper metabolism during lactation.Design: Observational study.Setting: Private and public clinics in Brazil.Patient(s): Lactating mothers attending the family planning clinic of the University of Brasilia.Intervention(s): The OCs used were a combination pill (0.15 mg of levonorgestrel and 0.03 mg of ethinyl estradiol) and a minipill (0.35 mg

Jose G Dorea; Edina S Miazaki

1999-01-01

75

Plasma manganese, selenium, zinc, copper, and iron concentrations in patients with schizophrenia  

Microsoft Academic Search

A number of essential trace elements play a major role in various metabolic pathways. Selenium (Se), manganese (Mn), copper\\u000a (Cu), zinc (Zn), and iron (Fe) are essential trace elements that have been studied in many diseases, including autoimmune,\\u000a neurological, and psychiatric disorders. However, the findings of previous research on the status of trace elements in patients\\u000a with schizophrenia have been

Medaim Yanik; Abdurrahim Kocyigit; Hamdi Tutkun; Huseyin Vural; Hasan Herken

2004-01-01

76

Simultaneous determination of cobalt, copper, iron and vanadium in crude petroleum oils by HPLC  

Microsoft Academic Search

A method has been developed for the simultaneous formation and solvent extraction of cobalt (II), copper (II), iron (II) and vanadium (IV) complexes of bis (acetylpivalylmethane)ethylenediamine (H2APM2en) in methyl isobutyl ketone. The complexes are eluted from a reversed phase HPLC column with a mixture of methanol:water:acetonitrile and detection was at 260 nm. The method has been applied to the simultaneous

S. N. Lanjwani; K. P. Mahar; A. H. Channer

1996-01-01

77

Presence of acute phase changes in zinc, iron, and copper metabolism in turkey embryos  

SciTech Connect

Acute phase changes in trace mineral metabolism were examined in turkey embryos. An endotoxin injection resulted in increased concentrations of serum copper and liver zinc and decreased concentrations of serum zinc in embryos incubated either in ovo or ex ovo. Changes in zinc and copper metabolism occurred when endotoxin either was injected intramuscularly, into the amnionic fluid, or administered onto the chorioallantoic membrane. Unlike poults, embryos did not respond to an inflammatory challenge with decreased serum iron concentrations. Acute phase changes in embryo serum zinc and copper as well as liver zinc concentrations were similar to those in poults. Increased liver zinc concentrations were associated with increased zinc in metallothionein (MT). An injection of a crude interleukin 1 preparation into embryos resulted in similar increases in hepatic zinc and MT concentrations as an endotoxin injection, suggesting a role for this cytokine in mediating the acute phase changes in embryonic zinc metabolism.

Klasing, K.C.; Richards, M.P.; Darcey, S.E.; Laurin, D.E.

1987-01-01

78

Effects of iron on Vitamin C/copper-induced hydroxyl radical generation in bicarbonate-rich water.  

PubMed

The aim of this study was to evaluate whether iron, like copper, could support Vitamin C mediated hydroxyl radical formation in bicarbonate-rich water. By using the hydroxyl radical indicator coumarin-3-carboxylic acid, we found that iron, in contrast to copper, was not capable to support Vitamin C induced hydroxyl radical formation. However, when 0.2 mg/l iron and 0.1 mg/l copper were both added to bicarbonate supplemented Milli-Q water, the Vitamin C induced formation of 7-hydroxycoumarin, as measured by HPLC analysis, was inhibited by 47.5%. The inhibition of hydroxyl radical formation by iron was also evident in the experiments performed on copper contaminated bicarbonate-rich household drinking water samples. In the presence of 0.2 mg/l of ferric iron the ascorbic acid induced hydroxyl radical formation was inhibited by 36.0-44.6%. This inhibition was even more significant, 47.0-59.2%, when 0.8 mg/l of ferric iron was present. None of the other redox-active metals, e.g. manganese, nickel or cobalt, could support ascorbic acid induced hydroxyl radical formation and did not have any impact on the ascorbic acid/copper-induced hydroxyl radical generation. Our results show, that iron cannot by itself produce hydroxyl radicals in bicarbonate rich water but can significantly reduce Vitamin C/copper-induced hydroxyl radical formation. These findings might partly explain the mechanism for the iron-induced protective effect on various copper related degenerative disorders that earlier has been observed in animal model systems. PMID:16036332

Jansson, Patric J; Del Castillo, Urko; Lindqvist, Christer; Nordström, Tommy

2005-05-01

79

Comparison of the mineralogy of the Boss-Bixby, Missouri copper-iron deposit, and the Olympic Dam copper-uranium-gold deposit, South Australia  

Microsoft Academic Search

An ore microscopic examination of 80 polished sections prepared from selected drill core specimens from the Boss-Bixby, Missouri copper-iron deposit has shown that its mineral assemblage is similar to that of the Olympic Dam (Roxby Downs) copper-uranium-gold deposit in South Australia. A comparison with the mineralogy reported for Olympic Dam shows that both deposits contain: 1) the principal minerals, magnetite,

R. T. Brandom; R. D. Hagni; C. R. Allen

1985-01-01

80

Responses of seedling growth and antioxidant activity to excess iron and copper in Triticum aestivum L.  

PubMed

The purpose of this study was to analyze phytotoxicity mechanism involved in root growth and to compare physiological changes in the leaves of wheat seedlings exposed to short term iron (Fe) and copper (Cu) stresses (0, 100, 300 and 500?M). All applied Fe or Cu concentrations reduced root and shoot lengths, but seed germination was inhibited by Cu only at 500?M. Analyses using fluorescent dye 2',7'-dichlorodihydrofluorescein diacetate indicated enhanced H(2)O(2) levels in seedling roots under Fe and Cu treatments. Cu stress at the same concentration induced a great reduction in cell viability and a strong damage on membrane lipid in the roots with respect to Fe treatment. Significant increases in the total chlorophyll (chl) content including chl a and chl b were observed in response to higher Fe concentrations, whereas the highest Cu concentration (500?M) led to significant decreases in the total chl content including chl a. Additionally, leaf peroxidase (POD) and ascorbate peroxidase (APX) were stimulated by Fe stress, but the highest Fe concentration exhibited inhibitory effect on leaf APX activity. In contrast, copper treatment resulted in an elevation in leaf catalase and POD activities. Therefore, H(2)O(2) content in the leaves associated with copper was significantly lower than that with iron at the same concentration. PMID:23025893

Li, Xiaoning; Ma, Haizhen; Jia, Pengxiang; Wang, Juan; Jia, Lingyun; Zhang, Tengguo; Yang, Yingli; Chen, Haijian; Wei, Xia

2012-12-01

81

Zebrafish in the sea of mineral (iron, zinc, and copper) metabolism  

PubMed Central

Iron, copper, zinc, and eight other minerals are classified as essential trace elements because they present in minute in vivo quantities and are essential for life. Because either excess or insufficient levels of trace elements can be detrimental to life (causing human diseases such as iron-deficiency anemia, hemochromatosis, Menkes syndrome and Wilson's disease), the endogenous levels of trace minerals must be tightly regulated. Many studies have demonstrated the existence of systems that maintain trace element homeostasis, and these systems are highly conserved in multiple species ranging from yeast to mice. As a model for studying trace mineral metabolism, the zebrafish is indispensable to researchers. Several large-scale mutagenesis screens have been performed in zebrafish, and these screens led to the identification of a series of metal transporters and the generation of several mutagenesis lines, providing an in-depth functional analysis at the system level. Moreover, because of their developmental advantages, zebrafish have also been used in mineral metabolism-related chemical screens and toxicology studies. Here, we systematically review the major findings of trace element homeostasis studies using the zebrafish model, with a focus on iron, zinc, copper, selenium, manganese, and iodine. We also provide a homology analysis of trace mineral transporters in fish, mice and humans. Finally, we discuss the evidence that zebrafish is an ideal experimental tool for uncovering novel mechanisms of trace mineral metabolism and for improving approaches to treat mineral imbalance-related diseases. PMID:24639652

Zhao, Lu; Xia, Zhidan; Wang, Fudi

2014-01-01

82

A Study of the Density of Unfilled States in Yttrium Barium Copper Oxide by means of Soft X-ray Continuum Isochromats  

NASA Astrophysics Data System (ADS)

The New Mexico State University two-crystal X-ray spectrometer is designed for spectroscopy in the soft X-ray region. It has a demountable ultra-high vacuum X-ray tube and is equipped with Potassium Acid Phthalate (KAP) crystals and a flowing gas proportional counter. The KAP crystals provide a unique and sensitive spectral window at a photon energy of 530 eV. The high signal to background available makes it possible to record continuum limit spectra as continuum isochromats. We intend to obtain continuum isochromats at 530 eV from Yttrium Barium Copper Oxide, a high temperature superconductor. Such spectra are convolutions of the energy spectrum of the incident electrons in the target with the product of the density of unfilled states and a matrix element for the transition. The spectrum of initially mono-energetic electrons in the target can be derived from equivalent photoemission experiments and used to obtain a representation of the density of unfilled states above the Fermi level of the target material from the isochromat spectra.

Rajaram, Ramya; Liefeld, Robert

2002-10-01

83

Property and microstructural nonuniformity in the yttrium-barium-copper-oxide superconductor determined from electrical, magnetic, and ultrasonic measurements. Ph.D. Thesis - Case Western Reserve Univ.  

NASA Technical Reports Server (NTRS)

The purpose of this dissertation was the following: (1) to characterize the effect of pore fraction on a comprehensive set of electrical and magnetic properties for the yttrium-barium-copper-oxide (YBCO) high temperature ceramic superconductor; and (2) to determine the viability of using a room-temperature, nondestructive characterization method to aid in the prediction of superconducting (cryogenic) properties. The latter involved correlating ultrasonic velocity measurements at room temperature with property-affecting pore fraction and oxygen content variations. The use of ultrasonic velocity for estimating pore fraction in YBCO is presented, and other polycrystalline materials are reviewed, modeled, and statistically analyzed. This provides the basis for using ultrasonic velocity to interrogate microstructure. The effect of pore fraction (0.10-0.25) on superconductor properties of YBCO samples was characterized. Spatial (within-sample) variations in microstructure and superconductor properties were investigated, and the effect of oxygen content on elastic behavior was examined. Experimental methods used included a.c. susceptibility, electrical, and ultrasonic velocity measurements. Superconductor properties measured included transition temperature, magnetic transition width, transport and magnetic critical current density, magnetic shielding, a.c. loss, and sharpness of the voltage-current characteristics. An ultrasonic velocity image constructed from measurements at 1mm increments across a YBCO sample revealed microstructural variations that correlated with variations in magnetic shielding and a.c. loss behavior. Destructive examination using quantitative image analysis revealed pore fraction to be the varying microstructural feature.

Roth, Don J.

1991-01-01

84

Shift of the Fermi level during cointercalation of copper and iron into TiSe2  

NASA Astrophysics Data System (ADS)

The influence of copper intercalation into the TiSe2 compound on the Fermi energy has been investigated using two independent methods. The first method is based on the analysis of the amplitude of the deformation (induced by impurity intercalation and providing the formation of polarons) as a function of the binding energy of the band of polaron states. For this purpose, the Fe x Cu y TiSe2 system has been synthesized for the first time by cointercalation of copper and iron into the TiSe2 lattice and studied. The second method consists in measuring the electromotive force of an open-circuit electrochemical cell with respect to a metal reference electrode. Both methods lead to consistent results in the range of moderate copper contents. However, considerable discrepancies have been observed in the copper concentration range that corresponds to the beginning of filling of Cu/Ti hybrid states. These discrepancies are explained by the softening of the lattice due to an increase in the density of states at the Fermi level.

Titov, A. A.; Titov, A. N.; Bushkova, O. V.; Tsurin, V. A.

2010-08-01

85

Determination of copper, scandium, molybdenum, tin, lead, and iron group elements in lunar surface materials  

NASA Technical Reports Server (NTRS)

Distribution regularities of copper, scandium, molybdenum, tin, lead, and iron group elements were investigated in basaltoid rocks of lunar and terrestrial origin. Samples of various regolith zones taken in the area of the Sea of Fertility were analyzed, along with samples of basic and ultrabasic rocks of the East African Rift for their content of the trace admixtures listed. Data obtained on the abundance of copper, scandium, molybdenum, tin, lead, cobalt, nickel, chromium, and vanadium in Luna 16 lunar surface material were compared with the abundance of these elements in samples of lunar rocks returned by Apollo 11, Apollo 12, and Apollo 14, with the exception of scandium; its content in the latter samples was considerably higher.

Pavlenko, L. I.; Simonova, L. V.; Karyakin, A. V.

1974-01-01

86

Small Sample Calorimetry, and Specific Heat of GADOLINIUM(1)BARIUM(2-X)STRONTIUM(X)COPPER(3)OXYGEN(7)  

NASA Astrophysics Data System (ADS)

The development of an automated small sample (0.5 to 50mg) calorimeter is discussed and evaluated. With this calorimeter, measurements of the specific heat of Gd_1Ba_{2-x}Sr_{x} Cu_3O_7 for x = 0, 0.25, and 0.5 in the temperature range 0.6 to 3 K are reported. Measurements on the x = 0 sample agree with data collected by other groups. In addition, measurements in magnetic fields from 0 to 3 T for the x = 0 sample are reported. In each case a peak in the specific heat at the antiferromagnetic ordering temperature (the Neel temperature) is recorded and analyzed. Strontium doping does not appreciably change the Neel temperature, but drastically changes the shape of the specific heat curve below the ordering temperature. The Neel temperature is reduced proportional to the square of the applied magnetic field, becoming no longer observable for fields greater than 3.0 T. Mean field theory is applied to the Neel temperature shift in order to gain a qualitative description for this behavior. The model calculation of the spin wave contribution to the low temperature specific heat discussed in the paper indicates that strong couplings along the c axis and weak dipolar couplings in the a-b plane are responsible for the antiferromagnetic order. The strontium doping further substantiates this argument by showing that the removal of the barium ions weakens the gadolinium coupling in the c direction by removing the super-exchange path.

Watson, Carter Harrison

87

Iron and Copper Act Synergistically To Delay Anaerobic Growth of Bacteria  

PubMed Central

Transition metals are known to cause toxic effects through their interaction with oxygen, but toxicity under anoxic conditions is poorly understood. Here we investigated the effects of iron (Fe) and copper (Cu) on the anaerobic growth and gene expression of the purple phototrophic bacterium Rhodopseudomonas palustris TIE-1. We found that Fe(II) and Cu(II) act synergistically to delay anaerobic growth at environmentally relevant metal concentrations. Cu(I) and Cu(II) had similar effects both alone and in the presence of ascorbate, a Cu(II) reductant, indicating that reduction of Cu(II) to Cu(I) by Fe(II) is not sufficient to explain the growth inhibition. Addition of Cu(II) increased the toxicity of Co(II) and Ni(II); in contrast, Ni(II) toxicity was diminished in the presence of Fe(II). The synergistic anaerobic toxicity of Fe(II) and Cu(II) was also observed for Escherichia coli MG1655, Shewanella oneidensis MR-1, and Rhodobacter capsulatus SB1003. Gene expression analyses for R. palustris identified three regulatory genes that respond to Cu(II) and not to Fe(II): homologs of cueR and cusR, two known proteobacterial copper homeostasis regulators, and csoR, a copper regulator recently identified in Mycobacterium tuberculosis. Two P-type ATPase efflux pumps, along with an FoF1 ATP synthase, were also upregulated by Cu(II) but not by Fe(II). An Escherichia coli mutant deficient in copA, cus, and cueO showed a smaller synergistic effect, indicating that iron might interfere with one or more of the copper homeostasis systems. Our results suggest that interactive effects of transition metals on microbial physiology may be widespread under anoxic conditions, although the molecular mechanisms remain to be more fully elucidated. PMID:23563938

Bird, Lina J.; Coleman, Maureen L.

2013-01-01

88

Iron and copper act synergistically to delay anaerobic growth of bacteria.  

PubMed

Transition metals are known to cause toxic effects through their interaction with oxygen, but toxicity under anoxic conditions is poorly understood. Here we investigated the effects of iron (Fe) and copper (Cu) on the anaerobic growth and gene expression of the purple phototrophic bacterium Rhodopseudomonas palustris TIE-1. We found that Fe(II) and Cu(II) act synergistically to delay anaerobic growth at environmentally relevant metal concentrations. Cu(I) and Cu(II) had similar effects both alone and in the presence of ascorbate, a Cu(II) reductant, indicating that reduction of Cu(II) to Cu(I) by Fe(II) is not sufficient to explain the growth inhibition. Addition of Cu(II) increased the toxicity of Co(II) and Ni(II); in contrast, Ni(II) toxicity was diminished in the presence of Fe(II). The synergistic anaerobic toxicity of Fe(II) and Cu(II) was also observed for Escherichia coli MG1655, Shewanella oneidensis MR-1, and Rhodobacter capsulatus SB1003. Gene expression analyses for R. palustris identified three regulatory genes that respond to Cu(II) and not to Fe(II): homologs of cueR and cusR, two known proteobacterial copper homeostasis regulators, and csoR, a copper regulator recently identified in Mycobacterium tuberculosis. Two P-type ATPase efflux pumps, along with an F(o)F(1) ATP synthase, were also upregulated by Cu(II) but not by Fe(II). An Escherichia coli mutant deficient in copA, cus, and cueO showed a smaller synergistic effect, indicating that iron might interfere with one or more of the copper homeostasis systems. Our results suggest that interactive effects of transition metals on microbial physiology may be widespread under anoxic conditions, although the molecular mechanisms remain to be more fully elucidated. PMID:23563938

Bird, Lina J; Coleman, Maureen L; Newman, Dianne K

2013-06-01

89

Simultaneous determination of iron and copper in children's sera by FAAS.  

PubMed

A new and simple flame atomic-absorption spectrometric (FAAS) method is proposed for simultaneous determination of iron and copper in children's sera. It is based on single-step sample pretreatment (deproteinization with 3 mol L-1 HCl, ratio 1:1) and single-step calibration using 1.5 mol L-1 HCl standard. During method's optimization a short multifactorial design experiment was used. The proposed method assures accuracy, sensitivity and precision comparable to that of the reference methods. The new approach is simple and time-, labour- and serum-saving, the latter being especially important in pediatric diagnostics. PMID:21406347

Luterotti, Svjetlana; Kordi?, Ton?ica Vukman; Dodig, Slavica

2011-03-01

90

Seasonal changes of zinc, copper, and iron in gilthead sea bream ( Sparus aurata ) fed fortified diets  

Microsoft Academic Search

Four groups of gilthead sea bream (Sparus aurata) were fed diets with additional metal contents: a basal diet (diet A) contained Zn at 60.9 ± 1.9 mg\\/kg diet, Cu at 3.9 ±\\u000a 0.9 mg\\/kg diet, and Fe at 138.3 ± 6.8 mg\\/kg diet; the other diets were supplemented with copper (20 mg\\/kg, diet B), iron (100\\u000a mg\\/kg, diet C), or

Emilio Carpeme; Rossella Serra; Maurizio Manera; Gloria Isani

1999-01-01

91

Contact Killing of Bacteria on Copper Is Suppressed if Bacterial-Metal Contact Is Prevented and Is Induced on Iron by Copper Ions  

PubMed Central

Bacteria are rapidly killed on copper surfaces, and copper ions released from the surface have been proposed to play a major role in the killing process. However, it has remained unclear whether contact of the bacteria with the copper surface is also an important factor. Using laser interference lithography, we engineered copper surfaces which were covered with a grid of an inert polymer which prevented contact of the bacteria with the surface. Using Enterococcus hirae as a model organism, we showed that the release of ionic copper from these modified surfaces was not significantly reduced. In contrast, killing of bacteria was strongly attenuated. When E. hirae cells were exposed to a solid iron surface, the loss of cell viability was the same as on glass. However, exposing cells to iron in the presence of 4 mM CuSO4 led to complete killing in 100 min. These experiments suggest that contact killing proceeds by a mechanism whereby the metal-bacterial contact damages the cell envelope, which, in turn, makes the cells susceptible to further damage by copper ions. PMID:23396344

Mathews, Salima; Hans, Michael

2013-01-01

92

Content of trace metals (iron, zinc, manganese, chromium, copper, nickel) in canned variegated scallops (Chlamys varia).  

PubMed

This article presents the results obtained through a study of the concentration of trace metals (iron, zinc, manganese, chromium, copper, nickel) in some conserves of variegated scallops (Chlamys varia, Bivalvia, Mollusca). A total of 300 samples of seven different commercial brands (named A, B, D, H, J, L and M) and one processing type, 'scallop sauce', were analysed. Samples were collected weekly in a large shopping centre in Santa Cruz de Tenerife during a 12-month period. Variegated scallops have considerable concentrations of zinc, cupper and manganese, so that their dietary intake constitutes an important source of these metals. However, they have low concentrations of chrome and nickel, and the levels of iron are similar to those found in other bivalve molluscs. PMID:19086337

Gutiérrez, Angel J; González-Weller, Dailos; González, Tomás; Burgos, Antonio; Lozano, Gonzalo; Hardisson, Arturo

2008-09-01

93

Age-associated changes of brain copper, iron, and zinc in Alzheimer's disease and dementia with lewy bodies.  

PubMed

Disease-, age-, and gender-associated changes in brain copper, iron, and zinc were assessed in postmortem neocortical tissue (Brodmann area 7) from patients with moderate Alzheimer's disease (AD) (n = 14), severe AD (n = 28), dementia with Lewy bodies (n = 15), and normal age-matched control subjects (n = 26). Copper was lower (20%; p < 0.001) and iron higher (10-16%; p < 0.001) in severe AD compared with controls. Intriguingly significant Group*Age interactions were observed for both copper and iron, suggesting gradual age-associated decline of these metals in healthy non-cognitively impaired individuals. Zinc was unaffected in any disease pathologies and no age-associated changes were apparent. Age-associated changes in brain elements warrant further investigation. PMID:25024342

Graham, Stewart F; Nasaruddin, Muhammad Bin; Carey, Manus; Holscher, Christian; McGuinness, Bernadette; Kehoe, Patrick G; Love, Seth; Passmore, Peter; Elliott, Christopher T; Meharg, Andrew A; Green, Brian D

2014-01-01

94

Liquid chromatographic determination of chelates of cobalt (II), copper (II) and iron (II) with 2-thiophonaldehyde-4-phenyl-3-thiosemicarbazone  

Microsoft Academic Search

Summary  A new chelating reagent 2-thiophenaldehyde-4-phenyl-3-thiosemicarbazone (TAPT) has been examined for high performance liquid\\u000a chromatographic (HPLC) separations of cobalt (II), copper(II) and iron (II) or cobalt (II), nickel (II), iron (II), copper\\u000a (II) and mercury (II) as metal chelates on a C18, 5?m column (2504 mm i.d.) The chelates were eluted isocratically with methanol: acetonitrile: water containing sodium acetate\\u000a and tetrabutylammonium

Y. Zhao

2000-01-01

95

The proteome of copper, iron, zinc, and manganese micronutrient deficiency in Chlamydomonas reinhardtii.  

PubMed

Trace metals such as copper, iron, zinc, and manganese play important roles in several biochemical processes, including respiration and photosynthesis. Using a label-free, quantitative proteomics strategy (MS(E)), we examined the effect of deficiencies in these micronutrients on the soluble proteome of Chlamydomonas reinhardtii. We quantified >10(3) proteins with abundances within a dynamic range of 3 to 4 orders of magnitude and demonstrated statistically significant changes in ~200 proteins in each metal-deficient growth condition relative to nutrient-replete media. Through analysis of Pearson's coefficient, we also examined the correlation between protein abundance and transcript abundance (as determined via RNA-Seq analysis) and found moderate correlations under all nutritional states. Interestingly, in a subset of transcripts known to significantly change in abundance in metal-replete and metal-deficient conditions, the correlation to protein abundance is much stronger. Examples of new discoveries highlighted in this work include the accumulation of O(2) labile, anaerobiosis-related enzymes (Hyd1, Pfr1, and Hcp2) in copper-deficient cells; co-variation of Cgl78/Ycf54 and coprogen oxidase; the loss of various stromal and lumenal photosynthesis-related proteins, including plastocyanin, in iron-limited cells; a large accumulation (from undetectable amounts to over 1,000 zmol/cell) of two COG0523 domain-containing proteins in zinc-deficient cells; and the preservation of photosynthesis proteins in manganese-deficient cells despite known losses in photosynthetic function in this condition. PMID:23065468

Hsieh, Scott I; Castruita, Madeli; Malasarn, Davin; Urzica, Eugen; Erde, Jonathan; Page, M Dudley; Yamasaki, Hiroaki; Casero, David; Pellegrini, Matteo; Merchant, Sabeeha S; Loo, Joseph A

2013-01-01

96

Thermodynamic and Structural Aspects of Equilibrium and Mechanically Milled Yttrium BARIUM(2) COPPER(3) OXYGEN(6+DELTA) Powder  

NASA Astrophysics Data System (ADS)

The equilibrium relationships between partial pressure of oxygen, temperature, lattice parameters and oxygen content in the YBa_2Cu_3O _{6+delta} superconductor were examined by differential scanning calorimetry, high -temperature x-ray diffraction, thermogravimetric analysis and measurement of pressure versus concentration isotherms. Oxygen pressures ranged from 1 mbar to 1013 mbar and temperatures ranged from 400^circC to 750 ^circC. Lattice parameters as a function of temperature and partial pressure of oxygen were measured. P(c) isotherms and TGA were used to measure oxygen content as a function of temperature. A phase line separating the low temperature orthorhombic phase and the high temperature tetragonal phase was determined. No evidence of a miscibility gap between the two phases was found in the range of temperatures and oxygen pressures explored. From the data, the excess enthalpy and entropy through the orthorhombic to tetragonal phase transition was calculated. It was found that the excess entropy is less than the entropy of mixing for an ideal solution. DSC was used to measure enthalpies for the transition and to calculate activation energies for the process. High temperature x-ray diffraction and differential scanning calorimetry were used to study the effect of high energy mechanical deformation on the structural and thermal characteristics of YBa_2Cu_3O _{6+delta} powder. Broadening of Bragg peaks due to the reduction of grain size makes the distinction between orthorhombic and tetragonal phases of YBa_2Cu _3O_{6+delta} difficult after only one hour of ball milling. The equilibrium orthorhombic to tetragonal phase transition may occur within the first hour of ball-milling. Longer milling times (> 5hrs) produce a cationic disorder on the yttrium and barium sites. A metastable cubic (Y_ {1/3}Ba_{2/3} )CuO_{2+delta} structure with a = 3.86A is formed. Further mechanical deformation does not induce the formation of an amorphous phase; rather, an eventual decomposition into the constituent oxides Y_2O_3 and BaCuO_2 is observed. Annealing of the metastable cubic (Y_{1/3} Ba_{2/3})CuO _{2+delta} phase in relatively low pressures of oxygen (>=100mbar) and at moderate temperatures (~400 -600^circC) produces an as yet unidentified cubic phase which is unstable in air and has a lattice constant of a = 5.47A.

Lee, David Soong-Hua

97

Copper and iron concentrations in Ascophyllum nodosum (Fucales, Phaeophyta) from different sites in Ireland and after culture experiments in relation to thallus age and epiphytism  

Microsoft Academic Search

In laboratory experiments, copper concentrations in plants of Ascophyllum nodosum (L.) Le Jolis (Fucales, Phaeophyta) increased with the concentrations in the culture media and were highest in younger, meristematic thallus parts. After initial accumulation in high-copper medium and subsequent transfer to clean seawater for 5 days, no release of copper could be detected. Iron concentrations in A. nodosum tissue were

Dagmar B. Stengel; Matthew J. Dring

2000-01-01

98

Micronutrient status in female university students: iron, zinc, copper, selenium, vitamin B12 and folate.  

PubMed

Young women are at an increased risk of micronutrient deficiencies, particularly due to higher micronutrient requirements during childbearing years and multiple food group avoidances. The objective of this study was to investigate biomarkers of particular micronutrients in apparently healthy young women. Female students (n = 308; age range 18-35 year; Body Mass Index 21.5 ± 2.8 kg/m2; mean ± SD) were recruited to participate in a cross-sectional study. Blood samples were obtained from participants in the fasted state and analysed for biomarkers of iron status, vitamin B12, folate, homocysteine, selenium, zinc, and copper. The results show iron deficiency anaemia, unspecified anaemia, and hypoferritinemia in 3%, 7% and 33.9% of participants, respectively. Low vitamin B12 concentrations (<120 pmol/L) were found in 11.3% of participants, while 4.7% showed sub-clinical deficiency based on serum methylmalonic acid concentrations >0.34 ?mol/L. Folate concentrations below the reference range were observed in 1.7% (serum) or 1% (erythrocytes) of participants, and 99.7% of the participant had erythrocyte-folate concentrations >300 nmol/L. Serum zinc concentrations <10.7 ?mol/L were observed in 2% of participants. Serum copper and selenium concentrations were below the reference range in 23% and 11% of participants, respectively. Micronutrient deficiencies including iron and vitamin B12, and apparent excess of folate are present in educated Australian female students of childbearing age, including those studying nutrition. The effects of dietary behaviours and food choices on markers of micronutrient status require further investigation. PMID:25401503

Fayet-Moore, Flavia; Petocz, Peter; Samman, Samir

2014-01-01

99

Micronutrient Status in Female University Students: Iron, Zinc, Copper, Selenium, Vitamin B12 and Folate  

PubMed Central

Young women are at an increased risk of micronutrient deficiencies, particularly due to higher micronutrient requirements during childbearing years and multiple food group avoidances. The objective of this study was to investigate biomarkers of particular micronutrients in apparently healthy young women. Female students (n = 308; age range 18–35 year; Body Mass Index 21.5 ± 2.8 kg/m2; mean ± SD) were recruited to participate in a cross-sectional study. Blood samples were obtained from participants in the fasted state and analysed for biomarkers of iron status, vitamin B12, folate, homocysteine, selenium, zinc, and copper. The results show iron deficiency anaemia, unspecified anaemia, and hypoferritinemia in 3%, 7% and 33.9% of participants, respectively. Low vitamin B12 concentrations (<120 pmol/L) were found in 11.3% of participants, while 4.7% showed sub-clinical deficiency based on serum methylmalonic acid concentrations >0.34 ?mol/L. Folate concentrations below the reference range were observed in 1.7% (serum) or 1% (erythrocytes) of participants, and 99.7% of the participant had erythrocyte-folate concentrations >300 nmol/L. Serum zinc concentrations <10.7 ?mol/L were observed in 2% of participants. Serum copper and selenium concentrations were below the reference range in 23% and 11% of participants, respectively. Micronutrient deficiencies including iron and vitamin B12, and apparent excess of folate are present in educated Australian female students of childbearing age, including those studying nutrition. The effects of dietary behaviours and food choices on markers of micronutrient status require further investigation. PMID:25401503

Fayet-Moore, Flavia; Petocz, Peter; Samman, Samir

2014-01-01

100

Haemolysis and Perturbations in the Systemic Iron Metabolism of Suckling, Copper-Deficient Mosaic Mutant Mice - An Animal Model of Menkes Disease  

PubMed Central

The biological interaction between copper and iron is best exemplified by the decreased activity of multicopper ferroxidases under conditions of copper deficiency that limits the availability of iron for erythropoiesis. However, little is known about how copper deficiency affects iron homeostasis through alteration of the activity of other copper-containing proteins, not directly connected with iron metabolism, such as superoxide dismutase 1 (SOD1). This antioxidant enzyme scavenges the superoxide anion, a reactive oxygen species contributing to the toxicity of iron via the Fenton reaction. Here, we analyzed changes in the systemic iron metabolism using an animal model of Menkes disease: copper-deficient mosaic mutant mice with dysfunction of the ATP7A copper transporter. We found that the erythrocytes of these mutants are copper-deficient, display decreased SOD1 activity/expression and have cell membrane abnormalities. In consequence, the mosaic mice show evidence of haemolysis accompanied by haptoglobin-dependent elimination of haemoglobin (Hb) from the circulation, as well as the induction of haem oxygenase 1 (HO1) in the liver and kidney. Moreover, the hepcidin-ferroportin regulatory axis is strongly affected in mosaic mice. These findings indicate that haemolysis is an additional pathogenic factor in a mouse model of Menkes diseases and provides evidence of a new indirect connection between copper deficiency and iron metabolism. PMID:25247420

Lenartowicz, Malgorzata; Starzynski, Rafal R.; Krzeptowski, Wojciech; Grzmil, Pawel; Bednarz, Aleksandra; Ogorek, Mateusz; Pierzchala, Olga; Staron, Robert; Gajowiak, Anna; Lipinski, Pawel

2014-01-01

101

78 FR 65573 - Migratory Bird Hunting; Application for Approval of Copper-Clad Iron Shot and Fluoropolymer Shot...  

Federal Register 2010, 2011, 2012, 2013

...1018-AY61, 1018-AY66 Migratory Bird Hunting; Application for Approval of Copper-Clad...Shot Coatings as Nontoxic for Waterfowl Hunting AGENCY: Fish and Wildlife Service, Interior...iron shot and fluoropolymer coatings for hunting waterfowl and coots. We published a...

2013-11-01

102

77 FR 59158 - Migratory Bird Hunting; Application for Approval of Copper-Clad Iron Shot and Fluoropolymer Shot...  

Federal Register 2010, 2011, 2012, 2013

...1018-AY61, 1018-AY66 Migratory Bird Hunting; Application for Approval of Copper-Clad...Shot Coatings as Nontoxic for Waterfowl Hunting AGENCY: Fish and Wildlife Service, Interior...iron shot and fluoropolymer coatings for hunting waterfowl and coots. We published a...

2012-09-26

103

The effect of nonylphenylpolyethylene glycol on the kinetics and morphology of silver cemented using zinc, iron, copper and aluminum  

Microsoft Academic Search

The effect of nonylphenylpolyethylene glycol (D1) and cementing agents zinc, iron, copper and aluminum on silver cementation kinetics and deposit morphology was investigated. It was found that D1 inhibits both silver cementation and cementing agent dissolution with greater effect on cementing agent dissolution. The silver deposition rate and metal consumption per mole silver decreased in the order Zn, Fe, Cu,

M. Karavasteva

2009-01-01

104

Structure of self-interstitial atom clusters in iron and copper  

NASA Astrophysics Data System (ADS)

The dislocation core structure of self-interstitial atom (SIA) clusters in bcc iron and fcc copper is determined using the hybrid ab initio continuum method of Banerjee [Philos. Mag. 87, 4131 (2007)]. To reduce reliance on empirical potentials and to facilitate predictions of the effects of local chemistry and stress on the structure of defects, we present here a hybrid extension of the Peierls-Nabarro continuum model, with lattice resistance to slip determined separately from ab initio calculations. A method is developed to reconstruct atomic arrangements and geometry of SIA clusters from the hybrid model. The results are shown to compare well with molecular-dynamics simulations. In iron, the core structure does not show dependence on the size of the self-interstitial cluster, and is nearly identical to that of a straight edge dislocation. However, the core structure of SIA clusters in Cu is shown to depend strongly on the cluster size. Small SIA clusters are found to have nondissociated compact dislocation cores, with a strong merging of Shockley partial dislocations and a relatively narrow stacking fault (SF) region. The compact nature of the SIA core in copper is attributed to the strong dependence of the self-energy on the cluster size. As the number of atoms in the SIA cluster increases, Shockley partial dislocations separate and the SF region widens, rendering the SIA core structure to that of an edge dislocation. The separation distance between the two partials widens as the cluster size increases, and tends to the value of a straight edge dislocation for cluster sizes above 400 atoms. The local stress is found to have a significant effect on the atomic arrangements within SIA clusters in copper and the width of the stacking faults. An applied external shear can delocalize the core of an SIA cluster in copper, with positive shear defined to be on the (111) plane along the [1¯1¯2] direction. For an SIA cluster containing 1600 atoms, a positive 1 GPa shear stress delocalizes the cluster and expands the SF to 30b , while a negative shear stress of 2 GPa contracts the core to less than 5b , where b is the Burgers vector magnitude.

Takahashi, Akiyuki; Ghoniem, Nasr M.

2009-11-01

105

Analytical methods for copper, zinc and iron quantification in mammalian cells.  

PubMed

Highly complex analytical methods with different accuracies of measurement, reproducibilities and ease of analyses are currently being used to quantify metals in cellular media and tissue samples. In this review, the analytical methods commonly used for iron, copper and zinc quantification in mammalian cells are presented and discussed. Herein, we present a literature survey of the most commonly found concentrations of these metals in various mammalian cells in culture and tissues. The aim of this review is to help researchers in metallomic-related areas identify the method that best suits their needs for the accurate quantification of these metals in cells. This accuracy goes beyond simple knowledge of the limit of detection of each technique and needs to be evaluated through comparisons with similar previous studies. PMID:23925479

Cerchiaro, Giselle; Manieri, Tania Maria; Bertuchi, Fernanda Rodrigues

2013-10-01

106

Selective nucleation of iron phthalocyanine crystals on micro-structured copper iodide.  

PubMed

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. PMID:25340949

Rochford, Luke A; Ramadan, Alexandra J; Heutz, Sandrine; Jones, Tim S

2014-12-14

107

Hot gas desulfurization with sorbents containing oxides of zinc, iron, vanadium and copper  

SciTech Connect

The main objective of this research is to evaluate the desulfurization performance of novel sorbents consisting of different combinations of zinc, iron, vanadium and copper oxides; and to develop a sorbent which can reduce H{sub 2}S levels to less than 1 ppmv, which can stabilize zinc, making operations above 650{degrees}C possible, and which can produce economically recoverable amounts of elemental sulfur during regeneration. This objective will be accomplished by evaluating the sorbent performance using fixed-bed and TGA experiments supported by sorbent characterization at various reaction extents. In the seventh quarter, the screening of the promoted sorbents in the packed bed reactor was continued. The results of this work were presented at the 1992 University Coal Research Contractors, Review Conference at Pittsburgh, PA.

Akyurtlu, A.; Akyurtlu, J.F.

1992-01-01

108

NORMAL:SUPERCONDUCTOR Point Contact Spectroscopy of Niobium, NEODYMIUM(1.85) CERIUM(0.15) Copper OXYGEN(4 - and Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA  

NASA Astrophysics Data System (ADS)

Point contacts are electrical contacts with dimensions smaller than the characteristic dimension associated with charge transport in the conducting material near the contact. In normal materials this characteristic dimension is the mean free path of the charge carriers (electrons or holes) and in a superconductor the characteristic dimension is the superconducting coherence length. In this limit, the transfer of charge through the contact is ballistic rather than diffusive. That is, the charge does not move through the contact with an average "drift" velocity, as in a bulk conductor, since the average distance between collisions is on the order of the contact size. As might be expected, the resistance of a point contact varies with changes in the scattering probability for charge carriers. By measuring nonlinearities in the voltage vs. current curves (V-I curves) of point contacts, information about the scattering mechanisms in conductors can be obtained. In this study, the differential resistance (dV/dI) vs. V curves of point contacts formed between normal metal wires and superconducting wedges were measured as a function of temperature. On elemental metal superconductor (niobium) and two high transition temperature superconductors (Nd _{1.85}Ce_ {0.15}CuO_{4-delta } and rm YBa_2 Cu_3 O_{7-delta}) were used. The results for niobium contacts with silver, aluminum and copper closely matched the predictions of a recent theory describing electrical conduction through normal:superconducting point contacts (1). The results for the differential resistance (dV/dI) at zero voltage bias for Ag:Nd_ {1.85}Ce_{0.15} CuO_{4-delta} point contacts also matched this theory, but other aspects of the dV/dI vs. V curves differed significantly from the theory. The dV/dI vs. V curves for Ag:rm YBa_2 Cu_3 O_{7-delta} ) point contacts were dominated by critical current effects and did not resemble the predicted form from the theory. Reference. (1) G. E. Blonder, M. Tinkham, and T. M. Klapwijk, Phys. Rev. B 25, 4515 (1982).

Reinertson, Randal C.

1991-02-01

109

Structure and properties of clusters of self-interstitial atoms in fcc copper and bcc iron  

NASA Astrophysics Data System (ADS)

Static and molecular dynamics simulations have been used with different types of interatomic potentials to investigate the structure, properties and stability of self-interstitial atom (SIA) clusters produced during irradiation. In f-iron (Fe), faulted clusters of <110> dumbbells are unstable for all the potentials. The most stable SIA clusters are sets of parallel <111> crowdions. Large clusters of this type form perfect dislocation loops with Burgers vector b = ½<111>. Small clusters (less than 9 SIAs) of <100> crowdions are stable at 0 K, but transform into a set of <111> crowdions on annealing. Larger <100> clusters are stable and form perfect dislocation loops with b = <100>. Both types of loops are glissile. In copper (Cu), clusters of parallel <100> dumbbells and <110> crowdions are stable. Large clusters of these types form faulted and perfect dislocation loops with b = 1/3<111> and ½<110> respectively. Small faulted clusters (less than 7 SIAs) of irregular shape can transform into a set of <110> crowdions during annealing. Larger faulted clusters are stable as hexagonal 1/3<111> Frank loops at temperatures of about up to 1050 K for a period of several hundred picoseconds. All faulted clusters are sessile. Clusters of <110> crowdions and ½<110> perfect loops are glissile and stable at all temperatures. When large enough (more than 49-64 SIAs) they can dissociate on their glide prism. Symmetric three-dimensional clusters of <100> dumbbells are stable at 0 K but during annealing they transform into sets of <110> crowdions. The results for both iron and copper are discussed and compared with experimental data and provide a basis for investigating and explaining the observed differences in radiation damage accumulation behaviour between fcc and bcc metals.

Osetsky, Yu. N.; Serra, A.; Singh, B. N.; Golubov, S. I.

2000-09-01

110

Size-dependent study of pulmonary responses to nano-sized iron and copper oxide nanoparticles.  

PubMed

The application of nanotechnology in various fields has resulted in a tremendous increase in the synthesis of variety of engineered nanoparticles (NPs). These applications are possible only due to the small size and large surface area of the NPs which imparts them unique properties. Inorganic oxide NPs as iron and copper oxide NPs are widely used in several biomedical and synthetic applications. The beneficial aspects of these NPs are concurrently associated with several drastic and deleterious effects as well. Size of the NPs plays a critical role in systemic clearance from the body. Initial studies have confirmed inflammatory responses in mice associated with non-biodegradable oxide NPs. The associated oxidative stress varied from mild effects to reactive oxygen species generation which can potentiate DNA damage or even induced carcinogenesis. Copper oxide NPs, in particular, induced acute toxicity and inflict neutrophil infiltration. This chapter focuses on the applicability of various in vivo techniques for studying the effect of these NPs, especially on the pulmonary system. These in vivo techniques would certainly provide a better understanding and insight into the mechanistic pathways by which these NPs interact with various organ systems in human body. PMID:23740125

Kumar, Rajiv; Nagesha, Dattatri K

2013-01-01

111

SOURCE ASSESSMENT: MAJOR BARIUM CHEMICALS  

EPA Science Inventory

This report summarizes data on air emissions from the production of major barium chemicals. Compounds studied include barium sulfide, barium carbonate, barium chloride, barium hydroxide, and barium sulfate. In order to evaluate potential environmental effects the source severity,...

112

Influence of iron overload on manganese, zinc, and copper concentration in rat tissues in vivo: study of liver, spleen, and brain.  

PubMed

Although hemochromatosis and pathological situations due to chronic iron overload have been extensively described, there is little information about the influence of iron on other trace elements in the cell. The aim of this study was to investigate changes in the concentration of zinc, manganese, and copper in the liver, spleen, and brain of rats after iron overload. Iron overload in Wistar rats was achieved by iron-supplemented diet or by intraperitoneal or intravenous injection of polymaltose iron. Iron, zinc, manganese, and copper were determined by atomic absorption spectrophotometry. Iron overload in rats, regardless of the route of its application, resulted in an increase not only of iron but also of zinc and manganese in the liver and the spleen, whereas the content of these metals in the brain did not change. The copper content of the liver, spleen, and brain remained the same after iron overload. The increase of zinc and manganese in the liver and spleen following iron overload was probably a result not only of increased intestinal absorption but also of increased uptake from the cell. This is also supported by the fact that no increase in the zinc and manganese concentrations occurred in the brain since, despite iron overload, the iron content remained constant. PMID:9801930

Vayenas, D V; Repanti, M; Vassilopoulos, A; Papanastasiou, D A

1998-01-01

113

The Menkes/Wilson disease gene homologue in yeast provides copper to a ceruloplasmin-like oxidase required for iron uptake.  

PubMed Central

The CCC2 gene of the yeast Saccharomyces cerevisiae is homologous to the human genes defective in Wilson disease and Menkes disease. A biochemical hallmark of these diseases is a deficiency of copper in ceruloplasmin and other copper proteins found in extracytosolic compartments. Here we demonstrate that disruption of the yeast CCC2 gene results in defects in respiration and iron uptake. These defects could be reversed by supplementing cells with copper, suggesting that CCC2 mutant cells were copper deficient. However, cytosolic copper levels and copper uptake were normal. Instead, CCC2 mutant cells lacked a copper-dependent oxidase activity associated with the extracytosolic domain of the FET3-encoded protein, a ceruloplasmin homologue previously shown to be necessary for high-affinity iron uptake in yeast. Copper restored oxidase activity both in vitro and in vivo, paralleling the ability of copper to restore respiration and iron uptake. These results suggest that the CCC2-encoded protein is required for the export of copper from the cytosol into an extracytosolic compartment, supporting the proposal that intracellular copper transport is impaired in Wilson disease and Menkes disease. Images Fig. 1 Fig. 3 PMID:7708696

Yuan, D S; Stearman, R; Dancis, A; Dunn, T; Beeler, T; Klausner, R D

1995-01-01

114

Copper(i)- and copper(0)-promoted homocoupling and homocoupling-hydrodehalogenation reactions of dihalogenoclathrochelate precursors for C-C conjugated iron(ii) bis-cage complexes.  

PubMed

Iron(ii) dibromo- and diiodoclathrochelates undergo copper(i)-promoted reductive homocoupling in HMPA at 70-80 °C leading to C-C conjugated dibromo- and diiodo-bis-clathrochelates in high yields. Under the same conditions, their dichloroclathrochelate analog does not undergo the same homocoupling reaction, so the target dichloro-bis-cage product was obtained in high yield via dimerization of its heterodihalogenide iodochloromonomacrobicyclic precursor. The use of NMP as a solvent at 120-140 °C gave the mixture of bis-clathrochelates resulting from a tandem homocoupling-hydrodehalogenation reaction: the initial acetonitrile copper(i) solvato-complex at a high temperature underwent re-solvatation and disproportionation leading to Cu(ii) ions and nano-copper, which promoted the hydrodehalogenation process even at room temperature. The most probable pathway of this reaction in situ includes hydrodehalogenation of the already formed dihalogeno-bis-clathrochelate via the formation of reduced anion radical intermediates. As a result, chemical transformations of the iron(ii) dihalogenoclathrochelates in the presence of an acetonitrile copper(i) solvato-complex were found to depend both on the nature of halogen atoms in their ribbed chelate fragments and on reaction conditions (i.e. solvent and temperature). The C-C conjugated iron(ii) dihalogeno-bis-clathrochelates easily undergo nucleophilic substitution with various N,S-nucleophiles giving ribbed-functionalized bis-cage species. These iron(ii) complexes were characterized by elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, (1)H and (13)C NMR spectroscopy, and by X-ray diffraction; their electrochemical properties were studied by cyclic voltammetry. The isomeric shift values in (57)Fe Mössbauer spectra of such cage compounds allowed identifying them as low-spin iron(ii) complexes, while those of the quadrupole splitting are the evidence for a significant TP distortion of their FeN6-coordination polyhedra. As follows from CV data, the C-C conjugated iron(ii) bis-clathrochelates undergo stepwise electrochemical reduction and oxidation giving mixed-valence Fe(II)Fe(I) and Fe(II)Fe(III) bis-cage intermediates. PMID:25056255

Varzatskii, Oleg A; Shul'ga, Sergey V; Belov, Alexander S; Novikov, Valentin V; Dolganov, Alexander V; Vologzhanina, Anna V; Voloshin, Yan Z

2014-11-18

115

Influence of iron overload on manganese, zinc, and copper concentration in rat tissues in vivo: study of liver, spleen, and brain  

Microsoft Academic Search

Although hemochromatosis and pathological situations due to chronic iron overload have been extensively described, there is\\u000a little information about the influence of iron on other trace elements in the cell. The aim of this study was to investigate\\u000a changes in the concentration of zinc, manganese, and copper in the liver, spleen, and brain of rats after iron overload. Iron\\u000a overload

D. V. Vayenas; M. Repanti; A. Vassilopoulos; D. A. Papanastasiou

1998-01-01

116

Study of Reaction Mechanisms for Copper-Cobalt-Iron Sulfide Concentrates in the Presence of Lime and Carbon  

NASA Astrophysics Data System (ADS)

The reaction mechanisms for the carbothermic reduction of complex mineral sulfide concentrates in the presence of lime were studied between 1073 K and 1323 K. The reaction mechanisms were studied by stopping the reduction experiments at different times and analyzing the reaction products by x-ray diffraction and scanning electron microscopy techniques. Magnetite (Fe3O4) and digenite (Cu1.8S) were the initial phases formed during reduction of CuFeS2 and Cu5FeS4 mineral particles, such that metallization of iron occurred before copper above 1173 K and at an equal stoichiometric ratio of CaO and C. The metallization of iron was found to take place via reduction of intermediate oxide phase (Fe3O4/FeO), whereas metallization of copper occurred via diffusion of S2- ions away from the mineral particles or via formation of Cu-O-S liquid phase. Metallic iron and cobalt were embedded in the copper matrix due to a preferential reduction of iron and cobalt from the Cu-Fe-S and Cu-Co-S type of mineral particles. The effects of CaO/C ratio were analyzed and the rate of reactions was increasing with an increase in the CaO/C ratio. The formation of liquid phase has been discussed. The experimental results were found to be in good agreement with the thermodynamic predictions.

Hara, Yotamu Stephen Rainford

2013-11-01

117

Rapid chemical synthesis of the barium ferrate super-iron Fe (VI) compound, BaFeO 4  

NASA Astrophysics Data System (ADS)

An alternate rapid synthesis of BaFeO 4 is demonstrated. Fe(VI) salts, including BaFeO 4, are energetic cathode materials in super-iron batteries ranging from primary to secondary, and including aqueous and non-aqueous cells. Of the Fe(VI) salts, BaFeO 4 sustains unusually facile charge transfer, of importance to the high power domain of alkaline batteries. Unlike previous syntheses, BaFeO 4 preparation is demonstrated from all solid state room temperature reactants. This eliminates several synthetic procedural steps and improves stability to approach that of the rigorously stable chemically synthesized K 2FeO 4 salt.

Licht, Stuart; Naschitz, Vera; Wang, Baohui

118

Reactivity of nanoparticles; interaction between zinc and copper oxide nanoparticles and iron ions in an alkaline medium  

Microsoft Academic Search

The reactivity of zinc and copper oxide nanoparticles was investigated upon their interaction with iron oxides. It was ascertained\\u000a that, depending on the reaction conditions, nanoparticles of zinc and copper ferrites (ZnFe2O4 and CuFe2O4) or core\\/shell nanoparticles (Fe3O4\\/ZnO) are produced. Size, composition, and structure of the resulting nanoparticles were determined by transmission electron\\u000a microscopy and X-ray diffraction analysis. The average

A. Ya. Shalyapina; L. A. Polyakova; M. A. Zaporozhets; E. M. Khokhlov; S. P. Gubin

2011-01-01

119

Barium Sulfate  

MedlinePLUS

... uses a computer to put together x-ray images to create cross-sectional or three dimensional pictures of the inside of the body). Barium sulfate is in a class of medications called radiopaque contrast media. It works by coating the esophagus, stomach, or ...

120

Evaluating the Metal Source(s) of Iron Oxide-Copper-Gold (IOCG) Deposits (Invited)  

NASA Astrophysics Data System (ADS)

Iron oxide - copper - gold deposits (IOCG) are characterized by high modal abundances of magnetite and/or hematite, ubiquitous and variable grades of Cu and Au, and, often, economic grades of other metals including REE, U, Ag, Mo and Zn. The largest deposits contain >1 billion tonnes of iron. There seems to be a general consensus that metals in IOCG deposits were transported by, and precipitated from, aqueous fluids. However, there is a lack of agreement for the source of the metal-bearing aqueous fluid(s) as well as the source of iron and other metals (i.e., magmatic or hydrothermal, or some combination of the two). Published fluid inclusion data indicate that metal-bearing aqueous fluids were trapped over a wide range of temperatures, with homogenization temperatures between 500 and 600 °C for inclusions associated with the precipitation of iron-oxide minerals, and between 300 and 500 °C for inclusions associated with main-stage sulfides (e.g., chalcopyrite, pyrite). The high trapping temperatures for fluid inclusions and the observation that some IOCG deposits appear to be related temporally and spatially to igneous intrusions, characteristics similar to those observed for porphyry-type ore deposits, have led some authors to propose that magmatic-hydrothermal aqueous fluids are responsible for IOCG formation. Others, however, favor a genetic model that invokes large-scale circulation of basinal brines, which are heated by magmatic intrusions and subsequently leach Fe and other metals from the crust. Evidence cited for this model includes the pervasive alkali metasomatism associated with some IOCG deposits, and the depletion of Fe, Cu and Au in some deposit wall rocks. Stable isotope evidence thus far is inconclusive. Published d34S values for IOCG deposits range from -30 to +30, but generally cluster around zero per mil. d18O ranges from ~0 to +10 per mil. Chlorine isotope values for fluids in inclusions liberated from quartz, calcite and apatite are consistent with mantle derived Cl, mixed with basinal brines. All of these data provide important constraints on various aspects of IOCG deposits. None of these data however provide direct evidence for the source of the metals in IOCG deposits. In this contribution, we will evaluate the source of Fe in selected IOCG deposits, as well as the plausibility for other metals to be magmatically sourced. Our approach combines: 1) solubility data for iron in aqueous fluid at temperatures that span the hydrothermal to magmatic regime; 2) new experimental data that constrain the fractionation of iron isotopes among silicate melt, aqueous fluid, magnetite, and sulfide, and at sub-solidus temperatures between aqueous fluid and magnetite; and 3) new iron isotope data for several IOCG deposits of the Coastal Cordillera in northern Chile. The combination of these data allows us to discriminate between the proposed basinal brine and magmatic-hydrothermal models.

Simon, A. C.; Bilenker, L.; Lundstrom, C.; Reich, M.; Barra, F.; Hanchar, J. M.; Westhues, A.

2013-12-01

121

Assimilation of zinc, cadmium, lead, copper, and iron by the spider Dysdera crocata, a predator of woodlice  

SciTech Connect

In this paper, an experiment is described on the assimilation of zinc, cadmium, lead, copper and iron by Dysdera crocata collected from a site in central Bristol. The spiders were fed on woodlice from their own site, and on woodlice from a site contaminated by a smelting works which contained much higher levels of zinc, cadmium and lead than the spiders would have been used to in their normal diet.

Hopkin, S.P.; Martin, M.H.

1985-02-01

122

Mineral chemistry of ore and hydrothermal alteration at the Sossego iron oxide–copper–gold deposit, Carajás Mineral Province, Brazil  

Microsoft Academic Search

The Sossego iron oxide–copper–gold deposit in the Carajás Mineral Province comprises two major orebodies, Sequeirinho and Sossego. Sodic alteration (albite–hematite) and sodic–calcic alteration zones represented by albite, ferro-edenite\\/hastingsite (up to 3.8 wt.% Cl), actinolite\\/magnesiohornblende, magnetite, titanite, epidote, and calcite are predominant at Sequeirinho. Magnetite bodies with envelopes of apatite-rich actinolitite were formed with the sodic–calcic event at high temperatures (~500 °C at

Lena Virgínia Soares Monteiro; Roberto Perez Xavier; Murray W. Hitzman; Caetano Juliani; Carlos Roberto de Souza Filho; Emerson de R. Carvalho

2008-01-01

123

The effect of occupational lead exposure on blood levels of zinc, iron, copper, selenium and related proteins.  

PubMed

The study objective was to evaluate the effect of occupational lead exposure on blood concentrations of zinc, iron, copper, selenium and proteins related to them, such as transferrin, caeruloplasmin and haptoglobin. The examined group consisted of 192 healthy male employees of zinc-lead works. By the degree of lead exposure, the exposed group was subdivided into three subgroups. The control group was composed of 73 healthy male administrative workers. The markers of lead exposure (blood levels of lead and zinc protoporphyrin) were significantly elevated in the exposed group compared with the control group. Additionally, concentrations of copper and caeruloplasmin were raised. The significant increase in haptoglobin level was observed only in the low exposure group. Selenium levels were significantly decreased, whereas iron, zinc and transferrin levels were unchanged in the exposed group compared with the control group. There were positive correlations between the lead toxicity parameters and the copper and caeruloplasmin levels. In conclusion, the effect of occupational exposure to lead on the metabolism of trace metals appears to be limited. However, significant associations between lead exposure and levels of copper and selenium were shown. Changed levels of positive acute-phase proteins, such as caeruloplasmin and haptoglobin, were also observed. PMID:22923205

Kasperczyk, Aleksandra; Prokopowicz, Adam; Dobrakowski, Micha?; Pawlas, Natalia; Kasperczyk, S?awomir

2012-12-01

124

Mixed messages in iron oxide–copper–gold systems of the Cloncurry district, Australia: insights from PIXE analysis of halogens and copper in fluid inclusions  

Microsoft Academic Search

Proterozoic rocks of the Cloncurry district in NW Queensland, Australia, are host to giant (tens to hundreds of square kilometers)\\u000a hydrothermal systems that include (1) barren regional sodic–calcic alteration, (2) granite-hosted hydrothermal complexes with\\u000a magmatic–hydrothermal transition features, and (3) iron oxide–copper–gold (IOCG) deposits. Fluid inclusion microthermometry\\u000a and proton-induced X-ray emission (PIXE) show that IOCG deposits and the granite-hosted hydrothermal complexes

Timothy Baker; Roger Mustard; Bin Fu; Patrick J. Williams; Guoyi Dong; Louise Fisher; Geordie Mark; Chris G. Ryan

2008-01-01

125

Phase diagram, thermal stability, and high temperature oxidation of the ternary copper-nickel-iron system  

NASA Astrophysics Data System (ADS)

Due to the aluminum industry demands, a large effort has recently been devoted to the development of special alloys to be used as inert anodes for a newly designed aluminum reduction cell. The implementation of this new technology aims at the replacement of the graphite anodes that have been used for over 100 years in aluminum smelting, which would reduce fossil carbon consumption, and eliminate the emission of carbon dioxide and of perfluorocarbons. Ternary alloys containing copper, nickel, and iron have been the subject of the research activities. The present research focused on the stability of the Cu-Ni-Fe alloys at high temperatures in oxidizing and fluoridating environments. The experimental methods included thermodynamic calculations of the phase diagram (Thermocalc), optical microscopy and microprobe microstructural and chemical investigations (EMPA), small-angle neutron scattering (SANS), differential thermal analysis (DTA), and air-oxidation studies. The results have led to the optimization of the Cu-Ni-Fe ternary phase diagram and to an extensive study of the thermodynamics and kinetics of the spinodal decomposition and discontinuous reactions occurring during ageing as a function of alloy composition. The oxidizing reactions occurring in air at high temperatures at the surface of the alloys have been also discussed in terms of thermodynamic and kinetic laws. The phase formation in a fluorine containing environment as encountered in an aluminum electrolytic cell is predicted using principles of physical chemistry.

Gallino, Isabella

126

Assessing Plasma Levels of Selenium, Copper, Iron and Zinc in Patients of Parkinson's Disease  

PubMed Central

Trace elements have been recognized to play an important role in the development of Parkinson’s disease (PD). However, it is difficult to precisely identify the relationship between these elements and the progression of PD because of an insufficient number of patients. In this study, quantifications of selenium (Se), copper (Cu), iron (Fe) and zinc (Zn) by atomic absorption spectrophotometry were performed in plasma from 238 PD patients and 302 controls recruited from eastern China, which is so far the largest cohort of PD patients and controls for measuring plasma levels of these elements. We found that plasma Se and Fe concentrations were significantly increased whereas Cu and Zn concentrations decreased in PD patients as compared with controls. Meanwhile, these four elements displayed differential changes with regard to age. Linear and logistic regression analyses revealed that both Fe and Zn were negatively correlated with age in PD patients. Association analysis suggests that lower plasma Se and Fe levels may reduce the risk for PD, whereas lower plasma Zn is probably a PD risk factor. Finally, a model was generated to predict PD patients based on the plasma concentrations of these four trace elements as well as other features such as sex and age, which achieved an accuracy of 80.97±1.34% using 10-fold cross-validation. In summary, our data provide new insights into the roles of Se, Cu, Fe and Zn in PD progression. PMID:24340079

Cheng, Xing; Wang, Jian-Yong; Hu, Bei-Lei; Zhang, Yan; Zhang, Xiong; Zhu, Jian-Hong

2013-01-01

127

High performance liquid chromatographic separation and UV determination of cobalt, copper iron and platinum in pharmaceutical preparations using bis(isovalerylacetone)ethylenediimine as complexing reagent  

Microsoft Academic Search

The reagent bis(isovalerylacetone)ethylenediimine(H2IVA2en) has been examined for HPLC separation and UV determination of cobalt, copper, iron and platinum using off-line precolumn derivatization and extraction in chloroform. The complexes of cobalt(II), cobalt(III), iron(II), iron(III) and the reagent have been subsequently separated on a Microsorb C-18 column. The complexes were eluted isocratically using ternary mixtures of methanol\\/water\\/acetonitrile. Detection was achieved by UV

Muhammad Yas Khuhawar; Shah Nawaz Lanjwani

1998-01-01

128

Factors Influencing the DNA Nuclease Activity of Iron, Cobalt, Nickel, and Copper Chelates  

PubMed Central

A library of complexes that included iron, cobalt, nickel, and copper chelates of cyclam, cyclen, DOTA, DTPA, EDTA, tripeptide GGH, tetrapeptide KGHK, NTA, and TACN was evaluated for DNA nuclease activity, ascorbate consumption, superoxide and hydroxyl radical generation, and reduction potential under physiologically relevant conditions. Plasmid DNA cleavage rates demonstrated by combinations of each complex and biological coreactants were quantified by gel electrophoresis, yielding second-order rate constants for DNAsupercoiled to DNAnicked conversion up to 2.5 ×106 M-1min-1, and for DNAnicked to DNAlinear up to 7 ×105 M-1min-1. Relative rates of radical generation and characterization of radical species were determined by reaction with the fluorescent radical probe TEMPO-9-AC and rhodamine B. Ascorbate turnover rate constants ranging from 9.1×10-3 to 8.2 min-1 were determined, although many complexes demonstrated no measureable activity. Inhibition and Freifelder-Trumbo analysis of DNA cleavage supported concerted cleavage of dsDNA by a metal associated ROS in the case of Cu2+(aq), Cu-KGHK, Co-KGHK, and Cu-NTA and stepwise cleavage for Fe2+(aq), Cu-cyclam, Cu-cyclen, Co-cyclen, Cu-EDTA, Ni-EDTA, Co-EDTA, Cu-GGH, and Co-NTA. Reduction potentials varied over the range from -362 mV to +1111 mV versus NHE, and complexes demonstrated optimal catalytic activity in the range of the physiological redox coreactants ascorbate and peroxide (-66 to +380 mV). PMID:21815680

Joyner, Jeff C.; Reichfield, Jared; Cowan, J. A.

2012-01-01

129

Copper  

MedlinePLUS

... copper status and certain CVD risk markers in young healthy women. Br J Nutr. 2005;94:231-236. Cassileth B. The Alternative Medicine Handbook: The Complete Reference Guide to Alternative and Complementary Therapies. New York, NY: W.W. Norton; 1998. Castillo-Durán C, Fisberg M, ...

130

Biochemical lesions in copper-deficient rats caused by secondary iron deficiency. Derangement of protein synthesis and impairment of energy metabolism  

PubMed Central

Severe copper deficiency was induced in rats by rearing nursing dams and their offsprings on a semisynthetic diet comprising all the requisite nutrients and trace metals except copper. The copper-deprived rats exhibited growth retardation, severe anaemia, loss of caeruloplasmin, decrease of cytochrome oxidase, accumulation of salt-soluble collagen and a drastic decrease in iron in plasma and liver. Apart from these characteristic signs of deficiency, a marked inhibition of protein synthesis was found to occur both in vivo and in cell-free liver preparations. The curtailed ability to carry out endogenously coded amino acid incorporation into protein contrasted with the unimpaired poly(U)-acid-directed phenylalanine polymerization. This inhibition pattern, as well as the attendant disaggregation of the liver polyribosomes, suggested that the primary biosynthetic lesion was located at the stage of peptide-chain initiation. Concurrently with this alteration there was a pronounced depletion of the hepatic ATP content, associated with a parallel depression of mitochondrial respiration and an enhancement of ATPase activity. Supplementation of the copper-deficient diet with a 2–4-fold excess of iron (relative to the standard diet) prevented growth retardation and anaemia and restored normal energy metabolism, as well as unimpaired protein-synthesizing capacity. The conclusion that these disturbances were primarily determined by the secondary iron deficiency was also borne out by the finding that similar alterations occurred in rats maintained on a copper-sufficient but iron-deficient diet. On the other hand, the iron-fortified diet failed to reverse the other signs of copper deficiency, namely the loss of caeruloplasmin, the diminished rate of cytochrome oxidase and the increase of soluble collagen. The interrelations between the various biochemical lesions induced by deprivation of copper or iron are discussed and the possible role of ATP depletion in determining the derangement of protein synthesis is considered. PMID:6258558

Weisenberg, Emil; Halbreich, Avraham; Mager, Jacob

1980-01-01

131

Effects of sulfur, zinc, iron, copper, manganese, and boron applications on sunflower yield and plant nutrient concentration  

SciTech Connect

Sulfur, zinc, iron, copper, manganese, and boron application did not affect the seed yield or oil percentage of sunflower (Helianthus annuus L.) on both dryland and irrigated soils in North Dakota in 1981. Field averages indicated significant Zn, Mn, and B uptake by sunflower at the 12-leaf stage as a result of fertilization with these elements. Increased Zn uptake was also observed in the uppermost mature leaf at anthesis from zinc fertilization. Although sunflower yield from boron fertilization was not significantly different from the check, a trend was observed in which boron fertilization seemed to decrease sunflower yield. Sunflower yields from the boron treatment were the lowest out of seven treatments in three out of four fields. Also, sunflower yield from the boron treatment was significantly lower than both iron and sulfur treatments when all fields were combined.

Hilton, B.R.; Zubriski, J.C.

1985-01-01

132

Attenuation in iron of neutrons produced by 120 GeV/c positive hadrons on a thick copper target  

NASA Astrophysics Data System (ADS)

A deep penetration experiment in a thick iron shield was carried out at CERN, at the CERN-EU high-energy Field (CERF) facility. A 120 GeV/c positive hadron beam impinged on a 50 cm thick copper target located inside an irradiation cave covered by an iron shield, the thickness of which could be varied from 40 to 240 cm. Measurements of neutron fluence and ambient dose equivalent were performed with a Bonner Sphere Spectrometer and an extended-range rem counter and the results compared with Monte Carlo simulations carried out with the FLUKA code. A comparison with literature data shows an acceptable agreement. A discussion is also given on the contribution of the neutron background and of its influence on a deep penetration experiment.

Agosteo, Stefano; Pozzi, Fabio; Silari, Marco; Ulrici, Luisa

2013-10-01

133

New Measurements of the Densities of Copper, Nickel, and Iron Sulfide Liquids  

NASA Astrophysics Data System (ADS)

Density measurements of sulfide liquids in the Fe-Ni-Cu-S-O system were performed from 1150°C-1250°C under controlled oxygen and sulfur fugacities. Measurements were made using the modified single bob (MSB) Archimedean method using zirconia ceramic bobs and crucibles. A 0.005mm resolution micrometer was attached to an elevator, which raised the crucible and melt relative to the free-hanging, stationary bob. A 0.001 g resolution analytical balance connected to a laptop computer continuously recorded the buoyancy as a function of crucible elevation. Densities were calculated by converting elevation to immersed volume and regressing the slope of buoyancy versus volume immersed. log(fO2) in the experiments ranged from -7.8 to -12.6 and log(fS2) ranged from -0.9 to -3.3. 38 successful sulfide liquid density measurements were performed, with values ranging from 3.8 g/cc to 6.6 g/cc. Regression of the resulting data suggests that a simple linear volume mixing model is adequate to represent the compositional dependence of density in copper- and nickel-sulfide liquids. A moderate positive excess mixing volume appears to be justified in iron-sulfide liquids. This result, along with high derived partial molar volumes for oxygen and sulfur components, are qualitatively consistent with the suggestion that increasing pressure will partition oxygen and sulfur out of the sulfide liquid during planetary accretion. The MSB density measurement also provides information on the relative magnitude of gas-zirconia and sulfide-zirconia surface energies. Assuming most of the observed variation results from sulfide chemistry it appears that oxidizing conditions significantly decrease sulfide-zirconia surface energies (increase wetting). If we can extrapolate this result to silicate minerals, this would suggest that oxidizing conditions will decrease wetting angle and thus increase the potential for sulfide segregation during planetary formation. We hope to test this hypothesis soon. Our experience suggests that trivial modifications to the apparatus used in this study may provide an effective and reliable method for measuring liquid-solid surface energies in both sulfide and silicate systems. Such data would prove useful in both melt percolation and bubble nucleation and growth calculations.

Mioduszewski, L.; Kress, V. C.

2005-12-01

134

Copper and Iron Determination with [ N , N ?Bis(salicylidene)-2,2?-dimethyl-1,3-propanediaminato] in Edible Oils Without Digestion  

Microsoft Academic Search

A new method for the determination of copper(II) and iron(III) in liquid edible oils which does not require a digestion step\\u000a was developed. The suggested method involves extraction of metals with [N,N?-bis(salicylidene)-2,2?-dimethyl-1,3-propanediaminato] (LDM) followed by flame atomic absorption spectrometry measurement.\\u000a As a first step, metal complexes of copper(II) and iron(III) ions with LDM were investigated spectrophotometrically. After\\u000a the analytical properties

Eda Köse Baran; Sema Ba?dat Ya?ar

2010-01-01

135

Liquid chromatographic determination of cobalt(II), copper(II) and iron(II) using 2-thiophenaldehyde-4-phenyl-3-thiosemicarbazone as derivatizing reagent  

Microsoft Academic Search

The complexing reagent 2-thiophenaldehyde-4-phenyl-3-thiosemicarbazone (TAPT) was examined for high performance liquid chromatographic (HPLC) separations of cobalt(II), copper(II) and iron(II) or cobalt(II), nickel(II), iron(II), copper(II) and mercury(II) as metal chelates on a Microsorb C-18, 5-?m column (150×4.6 mm i.d.) (Rainin Instruments Woburn, MA, USA). The complexes were eluted isocratically with methanol:acetonitrile:water containing sodium acetate and tetrabutyl ammonium bromide (TBA). UV detection

M. Y Khuhawar; S. N Lanjwani

1998-01-01

136

Enhanced degradation of chlorobenzene in aqueous solution using microwave-induced zero-valent iron and copper particles.  

PubMed

Microwaves were applied to reduce the activation energy of chlorobenzene in aqueous solution and enhance its removal using nanoscale zero-valent iron (Fe0) or zero-valent copper (Cu0) particles as dielectric media. When Fe0 and Cu0 particles absorb microwave energy, the electrical potential difference causes the metal electrons to rotate faster, thus producing more heat. The microwave-irradiated metal particles reduced the chlorobenzene activation energy by 6.1 kJ/mol (13.3 kJ/mol versus 19.4 kJ/mol) for Fe0 and 5.4 kJ/mol (15.8 kJ/mol versus 21.4 kJ/mol) for Cu0 and enhanced the chlorobenzene removal 4.1 times (82.8% versus 20.4%) for Fe0 and 3.7 times (72.1% versus 19.5%) for Cu0. The Fe0 has a higher standard reduction potential than Cu0; it is capable of removing more chlorobenzene than Cu0 (82.8% versus 72.1%). Using the microwave-induced nano-scale iron or copper particle is effective in treating toxic organic substances, as demonstrated in this study. PMID:20669726

Lee, Chien-Li; Jou, Chih-Ju G; Wang, H Paul

2010-07-01

137

Origin of fluids in iron oxide–copper–gold deposits: constraints from ? 37 Cl, 87 Sr\\/ 86 Sr i and Cl\\/Br  

Microsoft Academic Search

The origin of the hypersaline fluids (magmatic or basinal brine?), associated with iron oxide (Cu–U–Au–REE) deposits, is controversial. We report the first chlorine and strontium isotope data combined with Cl\\/Br ratios of fluid inclusions from selected iron oxide–copper–gold (IOCG) deposits (Candelaria, Raúl–Condestable, Sossego), a deposit considered to represent a magmatic end member of the IOCG class of deposit (Gameleira), and

Massimo Chiaradia; Dave Banks; Robert Cliff; Robert Marschik; Antoine de Haller

2006-01-01

138

Iron  

MedlinePLUS

... shows that giving iron intravenously can improve some symptoms of heart failure. It is not yet known if taking an iron supplement by mouth would help.Attention deficit-hyperactivity disorder (ADHD). Developing research shows that taking iron sulfate ( ...

139

Effect of excess dietary iron as ferrous sulfate and excess dietary ascorbic acid on liver zinc, copper and sulfhydryl groups and the ovary  

SciTech Connect

Female guinea pigs of the NIH 13/N strain, weighing between 475 and 512 g, were fed diets supplemented with 50 to 2500 mg of iron per kg of diet as ferrous sulfate and 0.2 to 8.0 g of ascorbic acid per kg of diet. A significant effect was observed on tissue copper and zinc, ovary weight and liver protein sulfhydryl groups. The mean ovary weight for guinea pigs fed 2500 mg of iron was significantly less than that of animals fed 50 mg of iron, 0.045 +/- 0.012 g and 0.061 +/- 0.009 g, respectively. Liver zinc content of animals fed 2500 mg of iron and 200 mg of ascorbic acid per kg of diet was significantly less than that of animals fed 50 mg of iron and 200 mg of ascorbic acid, 16.3 +/- 3.3 ..mu..g and 19.6 +/- 1.6 ..mu..g, respectively. There was no difference in liver copper due to dietary iron, but when dietary ascorbic acid was increased to 8 g per kg of diet, there was a significant decrease (from 22.8 +/- 8.1 ..mu..g to 10.5 +/- 4.8 ..mu..g) in liver copper. Excess dietary ascorbic acid decreased ovarian zinc significantly when increased to 8 g per kg of diet, 2929 +/- 919 ..mu..g vs 1661 +/- 471 ..mu..g, respectively, when compared to the control group.

Edwards, C.H.; Adkins, J.S.; Harrison, B.

1986-03-05

140

Copper and iron isotope fractionation during weathering and pedogenesis: Insights from saprolite profiles  

NASA Astrophysics Data System (ADS)

Iron and copper isotopes are useful tools to track redox transformation and biogeochemical cycling in natural environment. To study the relationships of stable Fe and Cu isotopic variations with redox regime and biological processes during weathering and pedogenesis, we carried out Fe and Cu isotope analyses for two sets of basalt weathering profiles (South Carolina, USA and Hainan Island, China), which formed under different climatic conditions (subtropical vs. tropical). Unaltered parent rocks from both profiles have uniform ?56Fe and ?65Cu values close to the average of global basalts. In the South Carolina profile, ?56Fe values of saprolites vary from -0.01‰ to 0.92‰ in the lower (reduced) part and positively correlate with Fe3+/?Fe (R2 = 0.90), whereas ?65Cu values are almost constant. By contrast, ?56Fe values are less variable and negatively correlate with Fe3+/?Fe (R2 = 0.88) in the upper (oxidized) part, where large (4.85‰) ?65Cu variation is observed with most samples enriched in heavy isotopes. In the Hainan profile formed by extreme weathering under oxidized condition, ?56Fe values vary little (0.05-0.14‰), whereas ?65Cu values successively decrease from 0.32‰ to -0.12‰ with depth below 3 m and increase from -0.17‰ to 0.02‰ with depth above 3 m. Throughout the whole profile, ?65Cu positively correlate with Cu concentration and negatively correlate with the content of total organic carbon (TOC). Overall, the contrasting Fe isotopic patterns under different redox conditions suggest redox states play the key controls on Fe mobility and isotope fractionation. The negative correlation between ?56Fe and Fe3+/?Fe in the oxidized part of the South Carolina profile may reflect addition of isotopically light Fe. This is demonstrated by leaching experiments, which show that Fe mineral pools extracted by 0.5 N HCl, representing poorly-crystalline Fe (hydr)-oxides, are enriched in light Fe isotopes. The systematic Cu isotopic variation in the Hainan profile reflects desorption and downward transport of isotopically heavy Cu, leaving the organically-bound Cu enriched in light isotope as supported by the negative correlation of ?65Cu with TOC (R2 = 0.88). The contrasting (mostly positive vs. negative) Cu isotopic signatures in the upper parts of these two profiles can be attributed to the different climatic conditions, e.g., high rainfall at a tropical climate in Hainan favors desorption and the development of organism, whereas relatively dry climate in South Carolina favors Cu re-precipitation from soil solutions and adsorption onto Fe (hydr)-oxides. Our results highlight the potential applications of Fe and Cu isotopes as great tracers of redox condition, ancient climate and biological cycling during chemical weathering and pedogenic translocation.

Liu, Sheng-Ao; Teng, Fang-Zhen; Li, Shuguang; Wei, Gang-Jian; Ma, Jing-Long; Li, Dandan

2014-12-01

141

A multicommuted flow system for the determination of copper, chromium, iron and lead in lubricating oils with detection by flame AAS  

Microsoft Academic Search

In this work, a flow analysis procedure for the determination of copper, chromium, iron and lead in lubricating oils using flame AAS as detection technique is described. The flow manifold was designed to implement the multicommutation approach and it comprised three 3-way solenoid valves controlled by a personal computer. The flow system presented allowed to process the oil samples to

B. F. Reis; M. Knochen; G. Pignalosa; N. Cabrera; J. Giglio

2004-01-01

142

Preconcentration and determination of iron and copper in spice samples by cloud point extraction and flow injection flame atomic absorption spectrometry.  

PubMed

A flow injection (FI) cloud point extraction (CPE) method for the determination of iron and copper by flame atomic absorption spectrometer (FAAS) has been improved. The analytes were complexed with 3-amino-7-dimethylamino-2-methylphenazine (Neutral Red, NR) and octylphenoxypolyethoxyethanol (Triton X-114)wasadded as a surfactant. The micellar solutionwasheated above 50 degrees C and loaded through a column packed with cotton for phase separation. Then the surfactant-rich phase was eluted using 0.05 mol L(-1) H2SO4 and the analytes were determined by FAAS. Chemical and flow variables influencing the instrumental and extraction conditions were optimized. Under optimized conditions for 25 mL of preconcentrated solution, the enrichment factors were 98 and 69, the limits of detection (3s) were 0.7 and 0.3 ng mL(-1), the limits of quantification (10s) were 2.2 and 1.0 ng mL(-1) for iron and copper, respectively. The relative standard deviation (RSD) for ten replicate measurements of 10 ng mL(-1) iron and copper were 2.1% and 1.8%, respectively. The proposed method was successfully applied to determination of iron and copper in spice samples. PMID:20627408

Sahin, Ci?dem Arpa; Tokgöz, Ilknur; Bekta?, Sema

2010-09-15

143

Effect of copper and iron on the oxidative flavor deterioration of ice cream  

E-print Network

aateinisation and hc: ogenisation can have a pronounced effect cn the occixrrence of oxidised flavor defeo+s. . sr&sauk and '. opps (39, C2) reported that, copper-protein complex was catalytically active in ths oxid itive f3&vcr development clnlsad hy a E... aateinisation and hc: ogenisation can have a pronounced effect cn the occixrrence of oxidised flavor defeo+s. . sr&sauk and '. opps (39, C2) reported that, copper-protein complex was catalytically active in ths oxid itive f3&vcr development clnlsad hy a E...

Miah, Md. Abdul Hamid

2012-06-07

144

Prokaryotic iron superoxide dismutase replaces cytosolic copper, zinc superoxide dismutase in protecting yeast cells against oxidative stress.  

PubMed

The iron superoxide dismutase (FeSOD) gene of Escherichia coli was cloned in Saccharomyces cerevisiae cells deficient in copper,zinc superoxide dismutase (Cu,ZnSOD). FeSOD replaced Cu,ZnSOD in protecting the yeast cells against oxidative stress. In the recombinant strains the FeSOD gene, which was under the transcriptional control of the yeast phosphoglycerate kinase gene promoter, was functionally expressed at two different levels on episomal and centromeric plasmids. Despite suppression of methionine and lysine auxotrophy, the higher level of FeSOD activity was more beneficial to growth of the mutant yeast cells only when these were exposed to higher levels of oxidative stress induced by paraquat or 100% oxygen. In the presence of paraquat, there was a novel stimulation of FeSOD activity. This was associated with a marked increase in catalase activity, and a decrease in glutathione reductase activity. PMID:9503146

Agius, D R; Bannister, W H; Balzan, R

1998-01-01

145

Hot gas desulfurization with sorbents containing oxides of zinc, iron, vanadium and copper. Quarterly technical progress report, July 1992  

SciTech Connect

The main objective of this research is to evaluate the desulfurization performance of novel sorbents consisting of different combinations of zinc, iron, vanadium and copper oxides; and to develop a sorbent which can reduce H{sub 2}S levels to less than 1 ppmv, which can stabilize zinc, making operations above 650{degrees}C possible, and which can produce economically recoverable amounts of elemental sulfur during regeneration. This objective will be accomplished by evaluating the sorbent performance using fixed-bed and TGA experiments supported by sorbent characterization at various reaction extents. In the seventh quarter, the screening of the promoted sorbents in the packed bed reactor was continued. The results of this work were presented at the 1992 University Coal Research Contractors, Review Conference at Pittsburgh, PA.

Akyurtlu, A.; Akyurtlu, J.F.

1992-09-01

146

Removal of copper and iron by polyurethane foam column in FIA system for the determination of nickel in pierced ring.  

PubMed

Polyurethane foam (PUF) mini-column was used to eliminate copper and iron for the determination of nickel in pierced rings. The PUF mini-column was connected to FIA system for on-line sorption of copper and iron in complexes form of CuSCN(+) and FeSCN(2+). For this season, the acid solution containing a mixture of Ni(II), Fe(III), Cu(II) and SCN(-) ions was firstly flew into the PUF column. Then, the percolated solution which Fe(III) and Cu(II) ions is separated from analysis was injected into FIA system to react with 4-(2-pyridylazo) resorcinol (PAR) reagent in basic condition which this method is called pH gradient technique. The Ni-PAR complexes obtained were measured theirs absorbance at 500nm by UV visible spectrophotometer. In this study, it was found that Cu(II) and Fe(III) were completely to form complexes with 400mmol/L KSCN and entirely to eliminate in acidic condition at pH 3.0. In the optimum condition of these experiments, the method provided the linear relationship between absorbance and the concentration of Ni(II) in the range from 5.00 to 30.00mg/L. Linear equation is y=0.0134x+0.0033 (R(2)=0.9948). Precision, assessed in the term of the relative standard deviation, RSD, and accuracy for multiple determinations obtained in values of 0.77-1.73% and 97.4%, respectively. The level of an average amount of Ni(II) in six piercing rings was evaluated to be 14.78mg/g. PMID:25281109

Vongboot, Monnapat; Suesoonthon, Monrudee

2015-01-01

147

1. Introduction Copper, along with iron active sites dominate the field of  

E-print Network

to oxida- tion of substrates (amine, galactose, and catechol oxidases),[6] activation for hydroxylation proteins include hemocya- nin, tyrosinase, and catechol oxidase.[5, 7] The binuclear copper centers, ascorbate oxidase, ceruloplasmin and Fet3p)[7] or proton pumping (cytochrome c oxidase, which also contains

Chen, Peng

148

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

PubMed Central

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

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

2012-01-01

149

The Phalabowra (Palabora) carbonatite-hosted magnetite–copper sulfide deposit, South Africa: an end-member of the iron-oxide copper–gold–rare earth element deposit group?  

Microsoft Academic Search

Olympic Dam-type iron-oxide copper–gold deposits are widely recognised in terrains with significant Palaeoproterozoic to\\u000a Mesoproterozoic granitic magmatism. Most researchers favour a magmatic association for these deposits, but none of the 100–2000?Mt\\u000a recognised copper-bearing deposits has a spatial and\\/or temporal relationship to an intrusive body of sufficient dimensions\\u000a to produce the hosting giant breccia and\\/or hydrothermal systems. In other words, if

David I. Groves; Noreen M. Vielreicher

2001-01-01

150

Iron  

MedlinePLUS

... several factors [ 1 , 3 , 8 , 11-15 ]. Storage levels of iron have the greatest influence on iron ... RDA), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL). The RDA recommends the average daily intake ...

151

Laser-initiated combustion studies of selected aluminum, copper, iron, and nickel alloys  

NASA Technical Reports Server (NTRS)

The results of combustion studies at atmospheric pressure on ten metal alloys are presented. The alloys studied were aluminum alloys 1100, 2219, 6061, and tensile-50; 304, 347 and 21-6-9 stainless steel; inconel 600; beryllium copper and a bronze. It was found that once ignition was achieved all alloys would generally burn to completion. The overall combustion process appears to obey a first order rate process. Preliminary conclusions are presented along with recommendations for future work.

Bransford, J. W.; Clark, A. F.

1981-01-01

152

Recovering iron, manganese, copper, cobalt, and high-purity nickel from sea nodules  

NASA Astrophysics Data System (ADS)

Many studies have investigated methods of recovering valuable metals from sea nodules. Recently, a research group in Japan developed a smelting and chlorine process after investigating a variety of existing processes and comparing their respective efficiencies with the same nodules. The best results were obtained by combining pyrometallurgical and hydrometallurgical treatments, which enabled the efficient recovery of manganese, nickel, copper, and cobalt. High-purity nickel can be also produced through further solvent extraction.

Kohga, Tetsuyoshi; Imamura, Masaki; Takahashi, Junichi; Tanaka, Nobuhiro; Nishizawa, Tokuo

1995-12-01

153

Barium titanium glycolate: A new barium titanate powder precursor  

SciTech Connect

This paper describes the synthesis and structure of a barium titanium glycolate complex and the calcination into barium titanate preceramic powders that sinter into polycrystalline, tetragonal barium titanate having good dielectric properties.

Day, V.W.; Klemperer, W.G.; Payne, D.A. [Univ. of Nebraska, Lincoln, NE (United States)] [and others] [Univ. of Nebraska, Lincoln, NE (United States); and others

1996-02-01

154

Iron, zinc and copper in the Alzheimer's disease brain: a quantitative meta-analysis. Some insight on the influence of citation bias on scientific opinion  

PubMed Central

Dysfunctional homeostasis of transition metals is believed to play a role in the pathogenesis of Alzheimer’s disease (AD). Although questioned by some, brain copper, zinc, and particularly iron overload are widely accepted features of AD which have led to the hypothesis that oxidative stress generated from aberrant homeostasis of these transition metals might be a pathogenic mechanism behind AD. This meta-analysis compiled and critically assessed available quantitative data on brain iron, zinc and copper levels in AD patients compared to aged controls. The results were very heterogeneous. A series of heavily cited articles from one laboratory reported a large increase in iron in AD neocortex compared to age-matched controls (p<0.0001) while seven laboratories failed to reproduce these findings reporting no significant difference between the groups (p=0.76). A more than three-fold citation bias was found to favor outlier studies reporting increases in iron and this bias was particularly prominent among narrative review articles. Additionally, while zinc was not significantly changed in the neocortex (p=0.29), copper was significantly depleted in AD (p=0.0003). In light of these findings, it will be important to re-evaluate the hypothesis that transition metal overload accounts for oxidative injury noted in AD. PMID:21600264

Schrag, Matthew; Mueller, Claudius; Oyoyo, Udochukwu; Kirsch, Wolff M.

2011-01-01

155

Neutron Scattering Studies of Cuprates and Iron Pnictides.  

E-print Network

??Presented within are neutron scattering studies of several different high temperature superconducting materials: BaFe1.9Ni0.1As2 [Barium Iron Nickel Arsenic], BaFe1.85Ni0.15As2 [Barium Iron Nickel Arsenic], Ba0.67K0.33Fe2As2 [Barium… (more)

Liu, Mengshu

2014-01-01

156

Barium release system  

NASA Technical Reports Server (NTRS)

A chemical system is described for releasing a good yield of free barium neutral atoms and barium ions in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium. The barium is released in the vapor phase so that it can be ionized by solar radiation and also be excited to emit resonance radiation in the visible range. The ionized luminous cloud of barium becomes a visible indication of magnetic and electrical characteristics in space and allows determination of these properties over relatively large areas at a given time.

Lewis, B. W.; Stokes, C. S.; Smith, E. W.; Murphy, W. J. (inventors)

1973-01-01

157

Silencing the Menkes copper-transporting ATPase (Atp7a) gene in rat intestinal epithelial (IEC-6) cells increases iron flux via transcriptional induction of ferroportin 1 (Fpn1).  

PubMed

The Menkes copper-transporting ATPase (Atp7a) gene is induced in rat duodenum during iron deficiency, consistent with copper accumulation in the intestinal mucosa and liver. To test the hypothesis that ATP7A influences intestinal iron metabolism, the Atp7a gene was silenced in rat intestinal epithelial (IEC-6) cells using short hairpin RNA (shRNA) technology. Perturbations in intracellular copper homeostasis were noted in knockdown cells, consistent with the dual roles of ATP7A in pumping copper into the trans-Golgi (for cuproenzyme synthesis) and exporting copper from cells. Intracellular iron concentrations were unaffected by Atp7a knockdown. Unexpectedly, however, vectorial iron ((59)Fe) transport increased (?33%) in knockdown cells grown in bicameral inserts and increased further (?70%) by iron deprivation (compared with negative control shRNA-transfected cells). Additional experiments were designed to elucidate the molecular mechanism of increased transepithelial iron flux. Enhanced iron uptake by knockdown cells was associated with increased expression of a ferrireductase (duodenal cytochrome b) and activity of a cell-surface ferrireductase. Increased iron efflux from knockdown cells was likely mediated via transcriptional activation of the ferroportin 1 gene (by an unknown mechanism). Moreover, Atp7a knockdown significantly attenuated expression of an iron oxidase [hephaestin (HEPH); by ?80%] and membrane ferroxidase activity (by ?50%). Cytosolic ferroxidase activity, however, was retained in knockdown cells (75% of control cells), perhaps compensating for diminished HEPH activity. This investigation has thus documented alterations in iron homeostasis associated with Atp7a knockdown in enterocyte-like cells. Alterations in copper transport, trafficking, or distribution may underlie the increase in transepithelial iron flux noted when ATP7A activity is diminished. PMID:24174620

Gulec, Sukru; Collins, James F

2014-01-01

158

Molecular Structure of Barium Chloride  

NSDL National Science Digital Library

Barium Chloride was the byproduct of the discovery of radium by Madame Curie. When refining radium, the final separation resulted in barium chloride and radium chloride. Electrophoresis of barium chloride produces small-scale amounts of barium atom. This can be used for obtaining barium for commercial uses. Applications of barium chloride include stimulating the heart and other muscles for medicinal purposes, and also for softening water. Other uses of barium chloride include the manufacturing of barium salts, as pesticide, pigments, boiler detergent, in purifying sugar, as mordant in dyeing and printing textiles, and in the manufacture of caustic soda, polymers, and stabilizers.

2002-08-15

159

Bioaccumulation of lead, copper, iron, and zinc by fish in a transect of the Santa Catarina River in Cadereyta Jimenez, Nuevo Leon, Mexico  

SciTech Connect

Changes have been observed in the ichthyic species community, upriver in the San Juan River in Nuevo Leon, Mexico. A disappearance of Notropis amabilis, Notropis stramineus, Dionda episcopa and Campostoma anomalum and an increased mortality of Astyanax mexicanus, Lepomis macrochirus and Cichlasoma cyanoguttatum have been found. These changes were probably due to industrial and domestic discharges which produced high levels of lead, copper, iron and detergents in the water. The investigation reported here was done in order to detect the possible presence of lead, copper, iron and zinc in the river waters and also, to determine a probable bioaccumulation of these metals in fish species of the Santa Catarina River in the state of Nuevo Leon in northeastern Mexico, since this river transports domestic and industrial wastes of urban and suburban zones.

Not Available

1986-09-01

160

Reconnaissance-scale conceptual fuzzy-logic prospectivity modelling for iron oxide copper-gold deposits in the northern Fennoscandian Shield, Finland  

Microsoft Academic Search

The conceptual approach used in this study incorporates spatial analysis techniques for data integration and analysis to perform reconnaissance-scale mineral prospectivity mapping for iron oxide copper – gold (IOCG) mineralisation in Finland. The known IOCG occurrences in Finland are characterised by the following features: (i) an epigenetic magnetite-rich host-rock; (ii) an association of Fe – Cu – Au ± Co ± U; (iii) ore minerals comprising magnetite, chalcopyrite, pyrite or

V. Nykänen; D. I. Groves; V. J. Ojala; P. Eilu; S. J. Gardoll

2008-01-01

161

Tourmaline B-isotopes fingerprint marine evaporites as the source of high-salinity ore fluids in iron oxide copper-gold deposits, Carajás Mineral Province (Brazil)  

Microsoft Academic Search

The Carajás Mineral Province in northern Brazil containsa variety of world-class (>100 Mt ore) iron oxide copper-gold(IOCG) deposits, including the only Archean examples of thisdeposit class (e.g., the Igarapé Bahia\\/Alemãoand Salobo deposits). Tourmaline of schorl-dravite composition,a common gangue mineral in these deposits, precipitated shortlyprior to and after the ore assemblage. A boron isotope studyof texturally different tourmaline from three IOCG

Roberto Perez Xavier; Michael Wiedenbeck; Robert B. Trumbull; Ana M. Dreher; Lena V. S. Monteiro; Dieter Rhede; Carlos E. G. de Araújo; Ignacio Torresi

2008-01-01

162

Alterations in plasma essential trace elements selenium, manganese, zinc, copper, and iron concentrations and the possible role of these elements on oxidative status in patients with childhood asthma  

Microsoft Academic Search

The aim of the present study is to evaluate the status of plasma essential trace element selenium (Se), manganese (Mn), copper\\u000a (Cu), zinc (Zn), and iron (Fe) concentrations and the effect of these elements on oxidative status in patients with childhood\\u000a asthma. Plasma Se, Mn, Cu, and Zn concentrations were determined by atomic absorption spectrophotometry (AAS) and Fe concentrations,\\u000a malondialdehyde

A. Kocyigit; F. Armutcu; A. Gurel; B. Ermis

2004-01-01

163

Simultaneous high performance liquid chromatographic determination of vanadium, nickel, iron and copper in crude petroleum oils using bis(acetylpivalylmethane)ethylenediimine as a complexing reagent  

Microsoft Academic Search

A method is described for the simultaneous high performance liquid chromatographic (HPLC) determination of copper, iron, nickel and vanadium, based on complexation of analytes by bis(acetylpivalylmethane)ethylenediimine (H2APM2en) followed by solvent extraction and HPLC separation on a reversed-phase. C-18, 5 ?m column with UV detection at 260 nm. The method has been applied to the determination of metals in crude petroleum

M. Y. Khuhawar; S. N. Lanjwani

1996-01-01

164

Determination of Copper, Iron, Nickel, and Zinc in Ethanol Fuel by Flame Atomic Absorption Spectrometry Using On?Line Preconcentration System  

Microsoft Academic Search

In this work, an on?line system for preconcentration and determination of copper, iron, nickel, and zinc at µg L level by flame atomic absorption spectrometry (FAAS) has been developed. Amberlite XAD?4 functionalized with 3,4?dihydroxybenzoic acid packed in a minicolumn was used as metal sorbent. The retained metals can be quickly eluted from sorbent material, with the eluent stream consisting of hydrochloric

Leonardo S. G. Teixeira; Marcos de A. Bezerra; Valfredo A. Lemos; Hilda C. dos Santos; Djane S. de Jesus; Antônio C. S. Costa

2005-01-01

165

Copper and iron-pillared clay catalysts for the WHPCO of model and real wastewater streams from olive oil milling production  

Microsoft Academic Search

The properties of copper-based pillared clays (Cu-PILC) have been studied and compared with those of the analogous iron-based clays (Fe-PILC) in the wet hydrogen peroxide catalytic oxidation (WHPCO) of model phenolic compounds (p-coumaric and p-hydroxybenzoic acids) and real olive oil milling wastewater (OMW). These two catalysts show comparable performances in all these reactions, although they show some differences in the

Simona Caudo; Gabriele Centi; Chiara Genovese; Siglinda Perathoner

2007-01-01

166

Hydrothermal alteration, fluid inclusions and stable isotope systematics of the Alvo 118 iron oxide-copper-gold deposit, Carajás Mineral Province (Brazil): Implications for ore genesis  

Microsoft Academic Search

The Alvo 118 iron oxide-copper-gold (IOCG) deposit (170 Mt at 1.0 wt.% Cu, 0.3 g\\/t Au) lies in the southern sector of the Itacaúnas Shear Belt, Carajás Mineral Province, along a WNW-ESE-striking, 60-km-long shear zone, close to the contact of the ~2.76-Ga metavolcano-sedimentary Itacaiúnas Supergroup and the basement (~3.0 Ga Xingu Complex). The Alvo 118 deposit is hosted by mafic

Ignacio Torresi; Roberto Perez Xavier; Diego F. A. Bortholoto; Lena V. S. Monteiro

2011-01-01

167

Spatial and temporal zoning of hydrothermal alteration and mineralization in the Sossego iron oxide-copper-gold deposit, Carajás Mineral Province, Brazil: paragenesis and stable isotope constraints  

Microsoft Academic Search

The Sossego iron oxide-copper-gold deposit (245 Mt @ 1.1% Cu, 0.28 g\\/t Au) in the Carajás Mineral Province of Brazil consists of two major groups of orebodies (Pista-Sequeirinho-Baiano and Sossego-Curral) with distinct alteration assemblages that are separated from each other by a major high angle fault. The deposit is located along a regional WNW-ESE-striking shear zone that defines the contact

Lena V. S. Monteiro; Roberto P. Xavier; Emerson R. de Carvalho; Murray W. Hitzman; Craig A. Johnson; Carlos Roberto de Souza Filho; Ignácio Torresi

2008-01-01

168

Iron prevents ascorbic acid (vitamin C) induced hydrogen peroxide accumulation in copper contaminated drinking water.  

PubMed

Ascorbic acid (vitamin C) induced hydrogen peroxide (H(2)O(2)) formation was measured in household drinking water and metal supplemented Milli-Q water by using the FOX assay. Here we show that ascorbic acid readily induces H(2)O(2) formation in Cu(II) supplemented Milli-Q water and poorly buffered household drinking water. In contrast to Cu(II), iron was not capable to support ascorbic acid induced H(2)O(2) formation during acidic conditions (pH: 3.5-5). In 12 out of the 48 drinking water samples incubated with 2 mM ascorbic acid, the H(2)O(2) concentration exceeded 400 microM. However, when trace amounts of Fe(III) (0.2 mg/l) was present during incubation, the ascorbic acid/Cu(II)-induced H(2)O(2) accumulation was totally blocked. Of the other common divalent or trivalent metal ions tested, that are normally present in drinking water (calcium, magnesium, zinc, cobalt, manganese or aluminum), only calcium and magnesium displayed a modest inhibitory activity on the ascorbic acid/Cu(II)-induced H(2)O(2) formation. Oxalic acid, one of the degradation products from ascorbic acid, was confirmed to actively participate in the iron induced degradation of H(2)O(2). Ascorbic acid/Cu(II)-induced H(2)O(2) formation during acidic conditions, as demonstrated here in poorly buffered drinking water, could be of importance in host defense against bacterial infections. In addition, our findings might explain the mechanism for the protective effect of iron against vitamin C induced cell toxicity. PMID:16298750

Jansson, Patric J; Lindqvist, Christer; Nordström, Tommy

2005-11-01

169

Coumarin-based fluorescent probes for dual recognition of copper(II) and iron(III) ions and their application in bio-imaging.  

PubMed

Two new coumarin-based "turn-off" fluorescent probes, (E)-3-((3,4-dihydroxybenzylidene)amino)-7-hydroxy-2H-chromen-2-one (BS1) and (E)-3-((2,4-dihydroxybenzylidene)amino)-7-hydroxy-2H-chromen-2-one (BS2), were synthesized and their detection of copper(II) and iron(III) ions was studied. Results show that both compounds are highly selective for Cu²? and Fe³? ions over other metal ions. However, BS2 is detected directly, while detection of BS1 involves a hydrolysis reaction to regenerate 3-amino-7-hydroxycoumarin (3) and 3,4-dihydroxybenzaldehyde, of which 3 is able to react with copper(II) or iron(III) ions. The interaction between the tested compounds and copper or iron ions is associated with a large fluorescence decrease, showing detection limits of ca. 10?? M. Preliminary studies employing epifluorescence microscopy demonstrate that Cu²? and Fe³? ions can be imaged in human neuroblastoma SH-SY5Y cells treated with the tested probes. PMID:24419164

García-Beltrán, Olimpo; Cassels, Bruce K; Pérez, Claudio; Mena, Natalia; Núñez, Marco T; Martínez, Natalia P; Pavez, Paulina; Aliaga, Margarita E

2014-01-01

170

Fast ultrasound-assisted extraction of copper, iron, manganese and zinc from human hair samples prior to flow injection flame atomic absorption spectrometric detection.  

PubMed

A dynamic ultrasound-assisted extraction procedure utilizing diluted nitric acid was developed for the determination of copper, iron, manganese and zinc in human hair taken from workers in permanent contact with a polluted environment. The extraction unit of the dynamic ultrasound-assisted extraction system contains a minicolumn into which a specified amount of hair (5-50 mg) is placed. Once inserted into the continuous manifold, trace metals were extracted at 3 mL min(-1) with 3 mol L(-1) nitric acid under the action of ultrasound for 2 min for zinc and 3 min for copper, iron and manganese determination, and using an ultrasonic water-bath temperature of 70 degrees C for zinc and 80 degrees C for copper, iron and manganese determination. The system permits the direct analysis of hair and yields concentrations with relative standard deviations of <3% (n = 11). The applicability of the procedure was verified by analysing human hair samples from workers exposed to welding fumes, and its accuracy was assessed through comparison with a conventional sample dissolution procedure and the use of a certified reference material (BCR 397, human hair). PMID:17404713

Yebra-Biurrun, M C; Cespón-Romero, R M

2007-06-01

171

Coumarin-Based Fluorescent Probes for Dual Recognition of Copper(II) and Iron(III) Ions and Their Application in Bio-Imaging  

PubMed Central

Two new coumarin-based “turn-off” fluorescent probes, (E)-3-((3,4-dihydroxybenzylidene)amino)-7-hydroxy-2H-chromen-2-one (BS1) and (E)-3-((2,4-dihydroxybenzylidene)amino)-7-hydroxy-2H-chromen-2-one (BS2), were synthesized and their detection of copper(II) and iron(III) ions was studied. Results show that both compounds are highly selective for Cu2+ and Fe3+ ions over other metal ions. However, BS2 is detected directly, while detection of BS1 involves a hydrolysis reaction to regenerate 3-amino-7-hydroxycoumarin (3) and 3,4-dihydroxybenzaldehyde, of which 3 is able to react with copper(II) or iron(III) ions. The interaction between the tested compounds and copper or iron ions is associated with a large fluorescence decrease, showing detection limits of ca. 10?5 M. Preliminary studies employing epifluorescence microscopy demonstrate that Cu2+ and Fe3+ ions can be imaged in human neuroblastoma SH-SY5Y cells treated with the tested probes. PMID:24419164

Garcia-Beltran, Olimpo; Cassels, Bruce K.; Perez, Claudio; Mena, Natalia; Nunez, Marco T.; Martinez, Natalia P.; Pavez, Paulina; Aliaga, Margarita E.

2014-01-01

172

Synthesis and properties of ternary GIC with iron or copper chlorides  

NASA Astrophysics Data System (ADS)

The variety of graphite intercalation compounds (GIC) is provided by the possibility to obtain ternary intercalation (TGIC) compounds containing two or more intercalates. A wide range of metal chlorides (FeCl3, AlCl3, CuCl2, NiCl2) and Brönsted acids (HNO3, CH3COOH, H2SO4) are generally used as intercalates. Iron chloride intercalation into the graphite leads to the formation of binary GIC with composition C6nFeCl3. Iron chloride acts as intercalate and oxidizer for the graphite matrix. Oxidation ability is due to the evolving of chlorine gas. Intercalation of CuCl2 requires harder conditions and occurs only with Cl2 presence. Co-intercalation GICs with FeCl3 and CH3COOH were synthesized by electrochemical graphite oxidation in the mixed electrolyte. Bi-intercalation GICs containing CuCl2 and H2SO4 were obtained by successive graphite intercalation with metal chloride and acid. All the synthesized compounds were investigated by physicochemical analysis. New ternary intercalation compounds with the FeCl3 CH3COOH mixture or CuCl2 H2SO4 one were synthesized. The correlation between intercalation features and reagents intercalation ability was shown.

Shornikova, O. N.; Dunaev, A. V.; Maksimova, N. V.; Avdeev, V. V.

2006-05-01

173

Effects of chronic light/dark cycle on iron zinc and copper levels in different brain regions of rats.  

PubMed

In this study, we aimed to investigate whether chronic shift in light/dark cycle alters brain trace element concentrations. For this purpose, 20 male Wistar albino adult rats were weighed and randomly divided into three groups. The first group (n?=?6) was the control and had been subjected to 12/12-h light/dark cycle for 30 days. The second group (n?=?7) was subjected to 6/18-h light/dark cycle for 15 days, and the third group (n?=?7) was also subjected to 6/18-h light/dark cycle for 15 days and then returned to normal 12/12-h light/dark cycle for 15 days. When light/dark cycle protocols were completed, tissue specimens of the frontal lobe, temporal lobe, and brain stem were collected. Iron (Fe), zinc (Zn), and copper (Cu) concentrations of the frontal lobe, temporal lobe, and brain stem were determined by an atomic absorption spectrophotometer. When compared with controls, Fe levels of the temporal lobe significantly increased in 6/18-h light/dark cycle group (p?

Karakoc, Yunus; Buruk, Mehmet Seyfi; Aktan, Burak; Kirvar, Ramazan; Erdogan, Songul; Sahbaz, Mehmet Akif; Aksoy, Sevket; Gulyasar, Tevfik

2011-12-01

174

Copper stable isotopes as tracers of metal-sulphide segregation and fractional crystallisation processes on iron meteorite parent bodies  

NASA Astrophysics Data System (ADS)

We report high precision Cu isotope data coupled with Cu concentration measurements for metal, troilite and silicate fractions separated from magmatic and non-magmatic iron meteorites, analysed for Fe isotopes (? 57Fe; permil deviation in 57Fe/ 54Fe relative to the pure iron standard IRMM-014) in an earlier study ( Williams et al., 2006). The Cu isotope compositions (? 65Cu; permil deviation in 65Cu/ 63Cu relative to the pure copper standard NIST 976) of both metals (? 65Cu M) and sulphides (? 65Cu FeS) span much wider ranges (-9.30 to 0.99‰ and -8.90 to 0.63‰, respectively) than reported previously. Metal-troilite fractionation factors (? 65Cu M-FeS = ? 65Cu M - ? 65Cu FeS) are variable, ranging from -0.07 to 5.28‰, and cannot be explained by equilibrium stable isotope fractionation coupled with either mixing or reservoir effects, i.e. differences in the relative proportions of metal and sulphide in the meteorites. Strong negative correlations exist between troilite Cu and Fe (? 57Fe FeS) isotope compositions and between metal-troilite Cu and Fe (? 57Fe M-FeS) isotope fractionation factors, for both magmatic and non-magmatic irons, which suggests that similar processes control isotopic variations in both systems. Clear linear arrays between ? 65Cu FeS and ? 57Fe FeS and calculated Cu metal-sulphide partition coefficients (D Cu = [Cu] metal/[Cu] FeS) are also present. A strong negative correlation exists between ? 57Fe M-FeS and D Cu; a more diffuse positive array is defined by ? 65Cu M-FeS and D Cu. The value of D Cu can be used to approximate the degree of Cu concentration equilibrium as experimental studies constrain the range of D Cu between Fe metal and FeS at equilibrium to be in the range of 0.05-0.2; D Cu values for the magmatic and non-magmatic irons studied here range from 0.34 to 1.11 and from 0.04 to 0.87, respectively. The irons with low D Cu values (closer to Cu concentration equilibrium) display the largest ? 57Fe M-FeS and the lowest ? 65Cu M-FeS values, whereas the converse is observed in the irons with large values D Cu that deviate most from Cu concentration equilibrium. The magnitudes of Cu and Fe isotope fractionation between metal and FeS in the most equilibrated samples are similar: 0.25 and 0.32‰/amu, respectively. As proposed in an earlier study ( Williams et al., 2006) the range in ? 57Fe M-FeS values can be explained by incomplete Fe isotope equilibrium between metal and sulphide during cooling, where the most rapidly-cooled samples are furthest from isotopic equilibrium and display the smallest ? 57Fe M-FeS and largest D Cu values. The range in ? 65Cu M-FeS, however, reflects the combined effects of partial isotopic equilibrium overprinting an initial kinetic signature produced by the diffusion of Cu from metal into exsolving sulphides and the faster diffusion of the lighter isotope. In this scenario, newly-exsolved sulphides initially have low Cu contents (i.e. high D Cu) and extremely light ? 65Cu FeS values; with progressive equilibrium and fractional crystallisation the Cu contents of the sulphides increase as their isotopic composition becomes less extreme and closer to the metal value. The correlation between ? 65Cu M-FeS and ? 57Fe M-FeS is therefore a product of the superimposed effects of kinetic fractionation of Cu and incomplete equilibrium between metal and sulphide for both isotope systems during cooling. The correlations between ? 65Cu M-FeS and ? 57Fe M-FeS are defined by both magmatic and non-magmatic irons record fractional crystallisation and cooling of metallic melts on their respective parent bodies as sulphur and chalcophile elements become excluded from crystallised solid iron and concentrated in the residual melt. Fractional crystallisation processes at shallow levels have been implicated in the two main classes of models for the origin of the non-magmatic iron meteorites; at (i) shallow levels in impact melt models and (ii) at much deeper levels in models where the non-magmatic irons represent metallic melts that crystallised within the in

Williams, Helen M.; Archer, Corey

2011-06-01

175

Microstructural Evolution and Mechanical Properties of Fusion Welds in an Iron-Copper-Based Multicomponent Steel  

NASA Astrophysics Data System (ADS)

NUCu-140 is a copper-precipitation-strengthened steel that exhibits excellent mechanical properties with a relatively simple chemical composition and processing schedule. As a result, NUCu-140 is a candidate material for use in many naval and structural applications. Before NUCu-140 can be implemented as a replacement for currently used materials, the weldability of this material must be determined under a wide range of welding conditions. This research represents an initial step toward understanding the microstructural and mechanical property evolution that occurs during fusion welding of NUCu-140. Microhardness traverses and tensile testing using digital image correlation show local softening in the heat-affected zone (HAZ). Microstructural characterization using light optical microscopy (LOM) revealed very few differences in the softened regions compared with the base metal. Local-electrode atom-probe (LEAP) tomography demonstrates that local softening occurs as a result of dissolution of the Cu-rich precipitates. MatCalc kinetic simulations (Vienna, Austria) were combined with welding heat-flow calculations to model the precipitate evolution within the HAZ. Reasonably good agreement was obtained between the measured and calculated precipitate radii, number density, and volume fraction of the Cu-rich precipitates in the weld. These results were used with a precipitate-strengthening model to understand strength variations within the HAZ.

Farren, Jeffrey D.; Hunter, Allen H.; Dupont, John N.; Seidman, David N.; Robino, Charles V.; Kozeschnik, Ernst

2012-11-01

176

Adsorption and decomposition of hydrazine on metal films of iron, nickel, and copper  

SciTech Connect

The interaction of hydrazine with evaporated metal films of Fe, Ni, and Cu has been investigated in the temperature range 243-393 K. Dissociative chemisorption of hydrazine occurred on Fe and Ni films at 243 K with liberation of NH/sub 3/, N/sub 2/, and H/sub 2/ gases. Adsorption on Cu film at the same temperature was molecular and a significant fraction of the adsorption was reversible. Two different mechanisms have been suggested for the adsorption and the subsequent formation of the decomposition products. Ammonia was the main gaseous product of hydrazine decomposition on the films at all temperatures. The desorption of the products was more extensive in the case of Ni film as compared with the other two metals. The activation energy (E/sub a/) of hydrazine adsorption as well as the pre-exponential factor (A) in the rate equation remained independent of extent of adsorption. The relationship which was found to exist between the values of log A and those of E/sub a/ indicated the operation of a compensation effect in the hydrazine adsorption on the films. Copper film was found to have a greater capability for hydrazine adsorption than the other two films. The geometric requirements for appropriate hydrazine adsorption on this metal are probably more satisfied than on the other two metals. 27 references, 6 figures, 4 tables.

Al-Haydari, Y.K.; Saleh, J.M.; Matloob, M.H.

1985-07-18

177

Accumulation and fractionation of copper, iron, manganese, and zinc in calcareous soils amended with composts.  

PubMed

Amending soils with compost may lead to accumulation of metals and their fractions at various concentrations in the soil profile. The objectives of this study were to determine 1) the accumulation of Cu, Fe, Mn, and Zn with depth and 2) the distribution of water soluble, exchangeable, carbonate, Fe-Mn oxides, organic and residual forms of each metal in soils amended with MSW compost, co-compost, biosolids compost and inorganic fertilizer (as control). Total concentrations of Cu, Fe, Mn and Zn were concentrated in the 0-22 cm soil layer and scant in the rock layer. These metals were in the decreasing order of Fe > Mn > Zn > or = Cu. Copper, Fe, and Zn were predominantly in the residual form followed by fractions associated with Fe-Mn oxides, carbonate, organic, exchangeable and water soluble in all treatments except MSW compost amended soil where the organic fraction was higher than the carbonate fraction. In fertilizer, co-compost and biosolids compost treated soils Mn concentrated mainly in the Fe-Mn oxides form followed by residual, carbonate, and organic forms whereas, in MSW compost treated soil the same pattern occurred except that Mn organic fraction was higher than that in the carbonate form. The MSW compost has a greater potential to be used as a soil amendment to supply plants with Cu, Mn and Zn than other treatments in calcareous soils of south Florida. PMID:11409501

Zinati, G M; Li, Y; Bryan, H H

2001-03-01

178

Dielectric properties of cobalt substituted M-type barium hexaferrite prepared by co-precipitation  

Microsoft Academic Search

Barium hexaferrite was synthesised via the co-precipitation method using high purity nitrates, oxides and carbonates of iron\\u000a (III), barium (II) and ammonium hydroxide. Once a phase pure sample of barium hexaferrite was obtained, it was doped, by weight,\\u000a with 1, 2, 3, 5, 10, 15, 20 and 30% cobalt oxide (Co3O4). The addition of cobalt to the BaM had the

Philip Shepherd; Kajal K. Mallick; Roger J. Green

2007-01-01

179

Inductively coupled plasma atomic fluorescence spectrometric determination of cadmium, copper, iron, lead, manganese and zinc  

USGS Publications Warehouse

An inductively coupled plasma atomic fluorescence spectrometric method is described for the determination of six elements in a variety of geological materials. Sixteen reference materials are analysed by this technique to demonstrate its use in geochemical exploration. Samples are decomposed with nitric, hydrofluoric and hydrochloric acids, and the residue dissolved in hydrochloric acid and diluted to volume. The elements are determined in two groups based on compatibility of instrument operating conditions and consideration of crustal abundance levels. Cadmium, Cu, Pb and Zn are determined as a group in the 50-ml sample solution under one set of instrument conditions with the use of scatter correction. Limitations of the scatter correction technique used with the fluorescence instrument are discussed. Iron and Mn are determined together using another set of instrumental conditions on a 1-50 dilution of the sample solution without the use of scatter correction. The ranges of concentration (??g g-1) of these elements in the sample that can be determined are: Cd, 0.3-500; Cu, 0.4-500; Fe, 85-250 000; Mn, 45-100 000; Pb, 5-10 000; and Zn, 0.4-300. The precision of the method is usually less than 5% relative standard deviation (RSD) over a wide concentration range and acceptable accuracy is shown by the agreement between values obtained and those recommended for the reference materials.

Sanzolone, R. F.

1986-01-01

180

Effect of Copper and Nickel on the Transformation Kinetics of Austempered Ductile Iron  

NASA Astrophysics Data System (ADS)

The kinetics of reaction occurring during the austempering treatment of ductile iron (DI) containing different additions of Cu and Ni was investigated in this work. DI bars were heat treated in an instrumented dilatometer in order to follow the exhibited transformation kinetics. The dilatometric results indicated that the addition of Cu alone did not have a significant effect on the incubation times for the austempering transformation. Also, the addition of both, Cu and Ni resulted in a significant effect on reducing the transformation rates. It was found that the austempering process is characterized by two clearly distinguished transformation stages. In the initial stage, the addition of Cu, and to a greater extent, additions of both Cu and Ni led to reductions in the transformation rates shifting the maximum transformation rate values toward longer times. The outcome of this work indicates that during the first stage of austempering, nucleation of the ferrite plates occurs via a diffusionless mechanism while their growth is diffusion controlled. Moreover, after the maximum in the transformation rate has been reached, the growth of ferrite plates becomes dominant with the rate-limiting step becoming the diffusion of C into the surrounding austenite. A qualitative model for the austempering transformation is proposed in this work to account for the experimental observations.

Górny, Marcin; Tyra?a, Edward; Lopez, Hugo

2014-10-01

181

The long-term effects of copper surface area on menstrual blood loss and iron status in women fitted with an IUD.  

PubMed

The long-term effects of copper surface area on menstrual blood loss (MBL) and iron status (hemoglobin, hematocrit, red cell count and indices, and serum ferritin) were evaluated in 25 healthy women who were observed for a period of 3 years following insertion of an intrauterine device. MBL was determined objectively by the alkaline hematin method. The women (mean age 37.2 +/- 1.6 yr, range 27-46 yr) were fitted with a Multiload intrauterine device (IUD) with a copper surface area of either 250 mm2 (MLCu-250, n = 13) or 375 mm2 (MLCu-375, n = 12). MBL prior to IUD insertion was 55 +/- 8 ml for women subsequently fitted with a MLCu-250 and 59 +/- 9 ml for women fitted with a MLCu-375. An increase in MBL was recorded at all measurement points following IUD insertion (MLCu-250/MLCu-375: 3 months: 55/49%; 6 months: 58/49%; 12 months: 64/41%; 24 months: 55/49%; 36 months: 47/39%, NS). There were no significant differences in iron status parameters before IUD insertion between groups nor were there any significant changes recorded in any of these parameters after IUD insertion. Our findings that the increase in copper surface area from 250 mm2 to 375 mm2 had no effect on MBL were thus substantiated by the hematological findings. Based on the results of the present study, women from developed countries apparently tolerate an increased MBL of approximately 45% without developing anemia. Iron stores were unchanged indicating an adequate adaptive increase in intestinal iron absorption. PMID:8275696

Larsson, G; Milsom, I; Jonasson, K; Lindstedt, G; Rybo, G

1993-11-01

182

Detection of copper, lead, cadmium and iron in wine using electronic tongue sensor system.  

PubMed

An array of 10 potentiometric chemical sensors has been applied to the detection of total Fe, Cu, Pb and Cd content in digested wine. As digestion of organic matter of wine is necessary prior to the trace metal detection using potentiometric sensors, sample preparation procedures have been optimized. Different variants of wet and microwave digestion and dry ashing, 14 conditions in total, have been tested. Decomposition of organic matter was assessed using Fourier transform mid-infrared spectroscopy and total phenolic content. Dry ashing was found to be the most effective method of wine digestion. Measurements with sensors in individual solutions of Fe(III), Cu(II), Pb(II) and Cd(II) prepared on different backgrounds have shown that their detection limits were below typical concentration levels of these metals in wines and, in the case of Cu, Pb and Cd below maximum allowed concentrations. Detection of Fe in digested wine samples was possible using discrete iron-sensitive sensors with chalcogenide glass membranes with RMSEP of 0.05 mmol L(-1) in the concentration range from 0.0786 to 0.472 mmol L(-1). Low concentration levels of Cu, Pb and Cd in wine and cross-sensitivity of respective sensors resulted in the non-linearity of their responses, requiring back-propagation neural network for the calibration. Calibration models have been calculated using measurements in the model mixed solutions containing all three metals and a set of digested wine sample. RMSEP values for Cu, Pb and Cd were 3.9, 39 and 1.2 ?mol L(-1) in model solutions and 2, 150 and 1 ?mol L(-1) in digested wine samples. PMID:25127565

Simões da Costa, A M; Delgadillo, I; Rudnitskaya, A

2014-11-01

183

Iron(II) and copper(I) coordination polymers: electrochromic materials with and without chiroptical properties.  

PubMed

The electrochemical and optical properties of films prepared from two different Fe(II) coordination polymers (TPT[Fe(II)TPT](n)(PF(6))(2)(n) (TPT = terpyridine-phenyl-terpyridine) and CTPCT[Fe(II)CTPCT](n)(PF(6))(2)(n) (CTPCT = chiral terpyridine-phenyl-chiral terpyridine)) and a coordination polymer based on Cu(I) metal centers (PDP[Cu(I)PDP](n)(BF(4))(n)) (PDP = phenanthroline-dodecane-phenanthroline) have been studied. The oxidation of a PDP[Cu(I)PDP](n)(BF(4))(n) film coated on an indium-tin oxide (ITO) electrode by stepping the potential from 0.0 to +1.4 V vs Ag/AgCl led not only to the complete bleaching of the absorption in the visible region of the spectrum within 5 min but also to a redox-induced dissociation and dissolution of the polymer. The reverse reaction of binding and reassembling the polymer at the electrode surface, upon stepping the potential back to 0.0 V, occurred with a rate which was at least 1 order of a magnitude slower. In contrast, the bis(2,2':6',2' '-terpyridine)iron(II)-based redox polymers TPT[Fe(II)TPT](n)(PF(6))(2)(n) and CTPCT[Fe(II)CTPCT](n)(PF(6))(2)(n), during similar spectroelectrochemical experiments, not only exhibited a dramatically enhanced switching rate but also displayed symmetric switching kinetics. The films did not show signs of deterioration over 150 switching cycles. Additionally, in an effort to assemble an electrochromic device with chiroptical properties, the electrochromism of films generated from the enantiomerically pure CTPCT[Fe(II)CTPCT](n)(PF(6))(2)(n) polymer was studied through circular dichroism. PMID:12844311

Bernhard, Stefan; Goldsmith, Jonas I; Takada, Kazutake; Abruña, Héctor D

2003-07-14

184

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

PubMed

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. PMID:12088032

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

2002-01-01

185

Copper and Iron Homeostasis in Plants: The Challenges of Oxidative Stress  

PubMed Central

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

Pilon, Marinus

2013-01-01

186

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

187

Acute and subacute response of iron, zinc, copper and selenium in pigs experimentally infected with Actinobacillus pleuropneumoniae.  

PubMed

This study was performed to characterise the response of iron (Fe), zinc (Zn), copper (Cu) and selenium (Se) in bacterial-induced porcine acute phase reaction (APR). Twenty piglets were challenged by aerosolic infection with Actinobacillus pleuropneumoniae (A.pp.) serotype 2, ten piglets serving as controls. Blood sampling was done initially and at day 4 and 21 after infection, collection of liver tissue was done at day 21 (autopsy). A.pp.-infection caused fever and respiratory symptoms. APR at day 4 after infection was marked by an increase in total white blood cells, granulocytes and monocytes in whole blood samples and an increase in globulin/albumin ratio (G/A), ?2-globulins, C-reactive protein, haptoglobin, ceruloplasmin (Cp), Cu and Se in serum. Concurrently, there was a decrease in haemoglobin (Hb) and packed cell volume (PCV) in whole blood as well as a decrease in albumin, transferrin, total iron binding capacity and Fe in serum and Zn in plasma. The subacute stage at day 21 was characterised by progressively increased concentrations of G/A, ?-globulins and ?-globulins reflecting the specific immune reaction. Hb and PCV showed further decreases, all other parameters returned to the initial concentrations. Glutathione peroxidase activity in plasma and liver tissue remained unaffected by A.pp.-infection. The liver concentration (day 21) of Zn was found to be higher, that of Se was lower in the A.pp.-group, whereas hepatic concentrations of Cu and Fe were not affected by A.pp.-infection. In summary, the acute and subacute stages of A.pp.-infection were accurately characterised by the APR-related parameters. Se was only marginally affected by the A.pp.-infection. The elevated plasma Cu concentration may be a side effect of the transient hepatic induction of Cp synthesis. Zn responded, being distinctly reduced in plasma and probably having been sequestered in the liver tissue. Reduction in serum Fe can be regarded as an unspecific defence mechanism in A.pp.-infection to withdraw Fe from bacterial acquisition systems. PMID:25100437

Humann-Ziehank, Esther; Menzel, Anne; Roehrig, Petra; Schwert, Barbara; Ganter, Martin; Hennig-Pauka, Isabel

2014-10-01

188

Tailored Barium Swallow Study  

MedlinePLUS

Tailored Barium Swallow Study The TBS is a special study that is completed in radiology. The test evaluates the mouth and ... where foods and liquids go when a person swallows. It helps clinicians to identify the reasons for ...

189

Beta barium borate (BBO)  

Microsoft Academic Search

The paper contains a review of crystallographic, optical and nonlinear optical properties of beta barium borate (ß-BaB2O4 or BBO) crystal and presents a description of its typical applications in nonlinear optics and quantum electronics.

D. N. Nikogosyan

1991-01-01

190

Barium bright and heavy  

NASA Astrophysics Data System (ADS)

Katharina M. Fromm relates how barium and its ores went from a magical, glowing species that attracted witches and alchemists to components in a variety of compounds that are key parts of modern life.

Fromm, Katharina M.

2013-02-01

191

Origin of fluids in iron oxide-copper-gold deposits: constraints from ? 37Cl, 87Sr/86Sri and Cl/Br  

NASA Astrophysics Data System (ADS)

The origin of the hypersaline fluids (magmatic or basinal brine?), associated with iron oxide (Cu-U-Au-REE) deposits, is controversial. We report the first chlorine and strontium isotope data combined with Cl/Br ratios of fluid inclusions from selected iron oxide-copper-gold (IOCG) deposits (Candelaria, Raúl-Condestable, Sossego), a deposit considered to represent a magmatic end member of the IOCG class of deposit (Gameleira), and a magnetite-apatite deposit (El Romeral) from South America. Our data indicate mixing of a high ? 37Cl magmatic fluid with near 0‰ ? 37Cl basinal brines in the Candelaria, Raúl-Condestable, and Sossego IOCG deposits and leaching of a few weight percent of evaporites by magmatic-hydrothermal (?) fluids at Gameleira and El Romeral. The Sr isotopic composition of the inclusion fluids of Candelaria, Raúl-Condestable, and El Romeral confirms the presence of a non-magmatic fluid component in these deposits. The heavy chlorine isotope signatures of fluids from the IOCG deposits (Candelaria, Raúl-Condestable, Sossego), reflecting the magmatic-hydrothermal component of these fluids, contrast with the near 0‰ ? 37Cl values of porphyry copper fluids known from the literature. The heavy chlorine isotope compositions of fluids of the investigated IOCG deposits may indicate a prevailing mantle Cl component in contrast to porphyry copper fluids, an argument also supported by Os isotopes, or could result from differential Cl isotope fractionation processes (e.g. phase separation) in fluids of IOCG and porphyry Cu deposits.

Chiaradia, Massimo; Banks, Dave; Cliff, Robert; Marschik, Robert; de Haller, Antoine

2006-09-01

192

Fractionation of Fulvic Acid by Iron and Aluminum Oxides-Influence on Copper Toxicity to Ceriodaphnia dubia.  

PubMed

This study examines the effect on aquatic copper toxicity of the chemical fractionation of fulvic acid (FA) that results from its association with iron and aluminum oxyhydroxide precipitates. Fractionated and unfractionated FAs obtained from streamwater and suspended sediment were utilized in acute Cu toxicity tests on Ceriodaphnia dubia. Toxicity test results with equal FA concentrations (6 mg FA/L) show that the fractionated dissolved FA was 3 times less effective at reducing Cu toxicity (EC50 13 ± 0.6 ?g Cu/L) than were the unfractionated dissolved FAs (EC50 39 ± 0.4 and 41 ± 1.2 ?g Cu/L). The fractionation is a consequence of preferential sorption of molecules having strong metal-binding (more aromatic) moieties to precipitating Fe- and Al-rich oxyhydroxides, causing the remaining dissolved FA to be depleted in these functional groups. As a result, there is more bioavailable dissolved Cu in the water and hence greater potential for Cu toxicity to aquatic organisms. In predicting Cu toxicity, biotic ligand models (BLMs) take into account dissolved organic carbon (DOC) concentration; however, unless DOC characteristics are accounted for, model predictions can underestimate acute Cu toxicity for water containing fractionated dissolved FA. This may have implications for water-quality criteria in systems containing Fe- and Al-rich sediment, and in mined and mineralized areas in particular. Optical measurements, such as specific ultraviolet absorbance at 254 nm (SUVA254), show promise for use as spectral indicators of DOC chemical fractionation and inferred increased Cu toxicity. PMID:25289694

Smith, Kathleen S; Ranville, James F; Lesher, Emily K; Diedrich, Daniel J; McKnight, Diane M; Sofield, Ruth M

2014-10-21

193

Iron and copper isotope fractionation during filtration and ultrafiltration of boreal organic-rich waters  

NASA Astrophysics Data System (ADS)

Typical feature of all boreal surface waters is high concentration of dissolved (< 0.22 µm) organic matter (DOM) and iron, notably in the form of Fe(III)-OM complexes. Organic and organo-mineral colloids are the most likely carriers of trace metals such as Cu in rivers of the boreal zone. This work addresses colloidal speciation of Cu and Fe using conventional size separation technique, on-site frontal ultrafiltration. Specifically, we aimed to test the possibility of the presence of different pools of metal having specific isotopic signatures in different colloidal fractions using stable isotope measurements. We have chosen Cu for its high affinity to colloidal DOM and Fe for its tendency to form stable organo-mineral colloids of various size. Samples of natural waters were collected from small rivers, lakes, bogs, groundwater and soil environments in the Northern Karelia (NW Russia) during summer baseflow period. Large volumes (20-40 L) of water were filtered in the field through progressively decreasing pore size filters: 20, 10, 5, 0.8, 0.45, 0.22, 0.1 µm and 100, 10 and 1 kDa (1 kDa ~ 1 nm) using nylon and regenerated cellulose membranes and frontal ultrafiltration (Millipore, Amicon) devises. The homogeneity of the sample was verified by tracing radiogenic Sr isotopes in each fraction. In all filtrates and ultrafiltrates (permeates), and in selected retentates, stable isotopic composition of Cu and Fe was measured using double focusing high resolution MC-ICP MS (Neptune). We observe rather constant Cu isotopic ratio in all filtrate series and a systematic enrichment of heavy isotope of Fe with decreasing poresize. These preliminary results can be explained by strong complexation of Cu with small-size organic ligands of fulvic nature and its partial association with organo-mineral colloids. Both Fe(III) - OM complxeation and Fe(III) oxyhydroxides precipitation can be invoked to explain Fe isotope fractionation. This work allows, for the first, time, multi-isotopic approach to trace the origin of colloids in surficial waters and it provides new constrains on chemical speciation (and, thus, bioavailability) of metals in colloids of various size. The work is executed at a Russian Federal Property Fund and CNRS support (?? 08-05-00312_a, 07-05-92212-CNRS_a).

Ilina, Svetlana M.; Viers, Jerome; Pokrovsky, Oleg S.; Poitrasson, Franck; Lapitsky, Sergey A.; Alekhin, Yuriy V.

2010-05-01

194

Effects of silicon, copper and iron on static and dynamic properties of alloy 206 (aluminum-copper) in semi-solids produced by the SEED process  

NASA Astrophysics Data System (ADS)

The advantages of producing metal parts by rheocasting are generally recognised for common foundry alloys of Al-Si. However, other more performing alloys in terms of mechanical properties could have a great interest in specialized applications in the automotive industry, while remaining competitive in the forming. Indeed, the growing demand for more competitive products requires the development of new alloys better suited to semi-solid processes. Among others, Al-Cu alloys of the 2XX series are known for their superior mechanical strength. However, in the past, 2XX alloys were never candidates for pressure die casting. The main reason is their propensity to hot tearing. Semi-solid processes provide better conditions for molding with the rheological behavior of dough and molding temperatures lower reducing this type of defect. In the initial phase, this research has studied factors that reduce hot tearing susceptibility of castings produced by semi-solid SEED of alloy 206. Subsequently, a comparative study on the tensile properties and fatigue was performed on four variants of the alloy 206. The results of tensile strength and fatigue were compared with the specifications for applications in the automotive industry and also to other competing processes and alloys. During this study, several metallurgical aspects were analyzed. The following main points have been validated: i) the main effects of compositional variations of silicon, iron and copper alloy Al-Cu (206) on the mechanical properties, and ii) certain relationships between the mechanism of hot cracking and the solidification rate in semi-solid. Parts produced from the semi-solid paste coming from the SEED process combined with modified 206 alloys have been successfully molded and achieved superior mechanical properties than the requirements of the automotive industry. The fatigue properties of the two best modified 206 alloys were higher than those of A357 alloy castings and are close to those of the wrought alloy AA6061. At present, there is simply no known application for pressure die-cast alloy with 206 (Liquid Die-casting). This is mainly due to the high propensity to hot cracking and limitations facing the part geometry and the subsequent assembly. This study demonstrated that in addition to pieces produced by semi-solid die-casting using large variations in chemical composition, the SEED process allows obtaining spare sound (sound part) and more complex geometry. Moreover, as the semi-solid parts have less porosity, they can also be machined and welded for some applications. The conclusions of this study demonstrate significant progress in identifying the main issues related to the feasibility of die-casting good parts with high performance using the modified 206 alloy combined with SEED process. This work is therefore a baseline work in the development of new Al-Cu alloys for industries of semi-solid and, at the same time, for the expansion of aluminum for high performance applications in the industry. N.B. This thesis is part of a research project developed by the NSERC / Rio Tinto Akan Industrial Research Chair in Metallurgy of Innovative Aluminum Transformation (CIMTAL).

Lemieux, Alain

195

A Calorimetric Study of (PRASEODYMIUM(1.5) CERIUM(0.5)) STRONTIUM(2) COPPER(2) Niobium OXYGEN(10), Praseodymium BARIUM(2) COPPER(2) Niobium OXYGEN(8) and the Effects of Oxygen on CARBON(60) (buckminsterfullerene)  

NASA Astrophysics Data System (ADS)

As in the RBa_2Cu _3O_{7-delta} copper oxide system the Pr member of the (R _{1.5}Ce_{0.5 })Sr_2Cu_2 NbO10 system is isostructural but nonsuperconducting. The compound (Pr_{1.5}Ce_ {0.5})Sr_2Cu _2NbO10 is even more anomalous as there are two magnetic ordering transitions seen in susceptibility data. One occurs at 17 K and is attributed to ordering in Pr moments. The second transition at 53 K is believed to be the result of a re-ordering of the Cu^{2+} moments which order antiferromagnetically at much higher temperatures in these systems. The heat capacity of (Pr_{1.5 }Ce_{0.5})Sr _2CU_2NbO 10 and a structurally related compound PrBa_2Cu _2NbO_8 are reported from 5 K to 350 K. The data for (Pr_{1.5 }Ce_{0.5})Sr _2Cu_2NbO 10 show no evidence of either magnetic transition, an unprecedented result for the 17 K Pr order. Comparing the characteristics of these heat capacity measurements and other heat capacity and magnetic measurements reported previously we argue that the unusual characteristics of (Pr_ {1.5}Ce_{0.5} )Sr_2Cu_2 NbO10 are predominantly due to the structural differences between these systems. The heat capacity of C_{60 }, from 5 K to 350 K, is examined as a function of oxygen exposure. A method is devised, using a thermal gravimetric analysis study, which gives a qualitative test, based on x-ray diffraction results, for structural breakdown. The measured heat capacity of pristine C_{60 } is consistent with previous reports for the size (18 J/mol K) and position (260 K) of the structural phase transition and for the existence of a glass transition near 87 K. Exposure to oxygen at room temperature produces no change in either transition temperature as might be expected if oxygen were a bulk contaminant at room temperature and were attached to the molecular structure. It is also not clear from these data whether there is a difference in the entropy associated with the transitions. The same C60 sample was subsequently exposed to oxygen at 175 ^circC on a time scale which produced only a partial oxygenation (determined by mass change). The face-centered cubic (fcc) to simple cubic transition was no longer observed. The x-ray diffraction pattern however was unchanged from the room temperature fcc lattice pattern. These heat capacity data were taken on a calorimeter designed and built in this laboratory for measurements in the 4 K to 400 K temperature range. An overview of the calorimeter design and measurement techniques are given.

Barnes, David Edward

196

Chelatometric determination of calcium and magnesium in iron ores, slags, anorthosite, limestone, copper-nickel-lead-zinc ores and divers materials.  

PubMed

Chelatometric methods for the determination of calcium and magnesium in iron ores, slags, anorthosite, copper-nickel-lead-zinc ores and various other materials are described. Potential interfering elements are masked with triethanolamine and potassium cyanide. In one aliquot calcium is titrated at pH > 12, with calcein and thymolphthalein mixed indicator and in another aliquot calcium and magnesium are titrated in ammonia buffer, with o-cresolphthalein complexone screened with Naphthol Green B as indicator. The results compare favourably with certified values for reference materials of diverse nature. PMID:18962661

Hitchen, A; Zechanowitsch, G

1980-03-01

197

Determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys by atomic-absorption spectrophotometry.  

PubMed

A simple atomic-absorption spectrophotometry method is described for the determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys, with use of a single sample solution. The sample is dissolved in a mixture of hydrobromic acid and bromine, then fumed with sulphuric acid. The lead sulphate is dissolved in concentrated hydrochloric acid. The method is particularly suitable for the determination of silver and bismuth, which are co-precipitated with lead sulphate. The other elements can also be determined after removal of the lead sulphate by filtration. PMID:18964038

Chong, C

1986-01-01

198

Hydrothermal alteration, fluid inclusions and stable isotope systematics of the Alvo 118 iron oxide–copper–gold deposit, Carajás Mineral Province (Brazil): Implications for ore genesis  

Microsoft Academic Search

The Alvo 118 iron oxide–copper–gold (IOCG) deposit (170 Mt at 1.0 wt.% Cu, 0.3 g\\/t Au) lies in the southern sector of the\\u000a Itacaúnas Shear Belt, Carajás Mineral Province, along a WNW–ESE-striking, 60-km-long shear zone, close to the contact of the\\u000a ~2.76-Ga metavolcano-sedimentary Itacaiúnas Supergroup and the basement (~3.0 Ga Xingu Complex). The Alvo 118 deposit is hosted\\u000a by mafic and felsic metavolcanic

Ignacio Torresi; Roberto Perez Xavier; Diego F. A. Bortholoto; Lena V. S. Monteiro

199

Spatial and temporal zoning of hydrothermal alteration and mineralization in the Sossego iron oxide–copper–gold deposit, Carajás Mineral Province, Brazil: paragenesis and stable isotope constraints  

Microsoft Academic Search

The Sossego iron oxide–copper–gold deposit (245 Mt @ 1.1% Cu, 0.28 g\\/t Au) in the Carajás Mineral Province of Brazil consists\\u000a of two major groups of orebodies (Pista–Sequeirinho–Baiano and Sossego–Curral) with distinct alteration assemblages that are\\u000a separated from each other by a major high angle fault. The deposit is located along a regional WNW–ESE-striking shear zone\\u000a that defines the contact between

Lena V. S. Monteiro; Roberto P. Xavier; Emerson R. de Carvalho; Murray W. Hitzman; Craig A. Johnson; Carlos Roberto de Souza Filho; Ignácio Torresi

2008-01-01

200

Release of aluminum, arsenic, cadmium, chromium, copper, iron, lead, and zinc in a coal leachate, and their removal from solution undergoing neutralization  

SciTech Connect

Whole coal contains significant amounts of iron pyrite which is oxidized ultimately to ferric acid sulfate. As a result, trace elements are released from the coal and other minerals in potentially hazardous concentrations. The purpose of this research was to: (1) study the release and mobility of selected trace elements during the weathering of coal; (2) seek to understand factors controlling solubility of trace elements in a synthetic, acidic leachate undergoing gradual neutralization; and (3) develop a chemical thermodynamic computer model to predict the effects of dilution and neutralization of leachate on trace element mobility and speciation. Samples collected periodically from a slurry of whole ground coal in water were filtered and analyzed for dissolved sulfate (by ion chromatography), iron (by flame atomic absorption spectrophotometry), and Al, Zn, Cd, Cu, Cr, Pb, As, and Se (by graphite furnace AAS). Iron, copper, and probably arsenic tracked the production of sulfate, while aluminum, zinc, chromium, and cadmium concentrations were stable or rose slightly. A synthetic leachate of ferric sulfate and sulfuric acid was doped with trace levels of Al, Zn, Cu, Cd, Cr, Pb, As, and Se. Slow injection of sodium bicarbonate solution neutralized the stirred system, though hydrolysis of iron buffered the pH and 2.5.

Tatum, T.L.

1992-01-01

201

An intrusion-related origin for Cu-Au mineralization in iron oxide-copper-gold (IOCG) provinces  

NASA Astrophysics Data System (ADS)

Major Cu-Au deposits of iron oxide-copper-gold (IOCG) style are temporally associated with oxidized, potassic granitoids similar to those linked to major porphyry Cu-Au deposits. Stable and radiogenic isotope evidence indicates fluids and ore components were likely sourced from the intrusions. IOCG deposits form over a range of crustal levels because CO2-rich fluids separate from the magmas at higher pressures than in CO2-poor systems, thereby, promoting partitioning of H2O, Cl and metals to the fluid phase. At deep levels, the magma-fluid system cannot generate sufficient mechanical energy to fracture the host rocks as in porphyry systems and the IOCG deposits therefore form in a variety of fault-related structural traps where the magmatic fluids may mix with other fluids to promote ore formation. At shallow levels, the IOCG deposits form breccia and fracture-hosted mineralization styles similar to the hydrothermal intrusive breccias and sulphide vein systems that characterize many porphyry Cu-Au deposits. The fluids associated with IOCG deposits are typically H2O-CO2-salt fluids that evolve by unmixing of the carbonic phase and by mixing with fluids from other sources. In contrast, fluids in porphyry systems typically evolve by boiling of moderate salinity fluid to produce high salinity brine and a vapor phase commonly with input of externally derived fluids. These different fluid compositions and mechanisms of evolution lead to different alteration types and parageneses in porphyry and IOCG deposits. Porphyry Cu-Au deposits typically evolve through potassic, sericitic and (intermediate and/or advanced) argillic stages, while IOCG deposits typically evolve through sodic(-calcic), potassic and carbonate-rich stages, and at deeper levels, generally lack sericitic and argillic alteration. The common association of porphyry and IOCG Cu-Au deposits with potassic, oxidized intermediate to felsic granitoids, together with their contrasting fluid compositions, alteration styles and parageneses suggest that they should be considered as part of the broad family of intrusion-related systems but that they are typically not directly related to each other.

Pollard, Peter J.

2006-05-01

202

Characterization of iron- and sulphide mineral-oxidizing moderately thermophilic acidophilic bacteria from an Indonesian auto-heating copper mine waste heap and a deep South African gold mine  

Microsoft Academic Search

Iron- and chalcopyrite-oxidizing enrichment cultures were obtained at 50°C from acidic, high-temperature, copper\\/gold mine environments in Indonesia and South Africa. Over 90% copper yield was obtained from chalcopyrite concentrate with the Indonesian enrichment in 3 months with 2% solids concentration, when pH was maintained at around 2. Neither addition of silver cations nor an enhanced nutrient concentration influenced chalcopyrite leaching. Excision

Päivi H.-M. Kinnunen; Jaakko A. Puhakka

2004-01-01

203

Aspiration of barium contrast.  

PubMed

The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient's medical file was reviewed, images were found of a barium swallow study that the patient had undergone months earlier, and we were able to observe the exact moment of the aspiration of the contrast material. The patient had been asymptomatic since the test. PMID:25309769

Fuentes Santos, Cristina; Steen, Bárbara

2014-01-01

204

Aspiration of Barium Contrast  

PubMed Central

The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient's medical file was reviewed, images were found of a barium swallow study that the patient had undergone months earlier, and we were able to observe the exact moment of the aspiration of the contrast material. The patient had been asymptomatic since the test. PMID:25309769

Fuentes Santos, Cristina; Steen, Barbara

2014-01-01

205

Observed Barium Emission Rates  

NASA Technical Reports Server (NTRS)

The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

1993-01-01

206

Syntheses and structural characterization of iron(II) and copper(II) coordination compounds with the neutral flexible bidentate N-donor ligands  

NASA Astrophysics Data System (ADS)

Two new coordination compounds [Fe(bib)2(N3)2]n(1) and [Cu2(bpp)2(N3)4] (2) with azide and flexible ligands 1,4-bis(imidazolyl)butane (bib) and 1,3-bis(3,5-dimethylpyrazolyl)propane (bpp) were prepared and structurally characterized. In the 2D network structure of 1, the iron(II) ion lies on an inversion center and exhibits an FeN6 octahedral arrangement while in the dinuclear structure of 2, the copper(II) ion adopts an FeN5 distorted square pyramid geometry. In the complex 1, each ?2-bib acts as bridging ligand connecting two adjacent iron(II) ions while in the complex 2, the bpp ligand is coordinated to copper(II) ion in a cyclic-bidentate fashion forming an eight-membered metallocyclic ring. Coordination compounds 1 and 2 have been characterized by infrared spectroscopy, elemental analyses and single-crystal X-ray diffraction. Thermal analysis of polymer 1 was also studied.

Beheshti, Azizolla; Lalegani, Arash; Bruno, Giuseppe; Rudbari, Hadi Amiri

2014-08-01

207

Effects of microbial iron reduction and oxidation on the immobilization and mobilization of copper in synthesized Fe(III) minerals and Fe-rich soils.  

PubMed

The effects of microbial iron reduction and oxidation on the immobilization and mobilization of copper were investigated in a high concentration of sulfate with synthesized Fe(III) minerals and red earth soils rich in amorphous Fe (hydr)oxides. Batch microcosm experiments showed that red earth soil inoculated with subsurface sediments had a faster Fe(III) bioreduction rate than pure amorphous Fe(III) minerals and resulted in quicker immobilization of Cu in the aqueous fraction. Coinciding with the decrease of aqueous Cu, SO4(2-) in the inoculated red earth soil decreased acutely after incubation. The shift in the microbial community composite in the inoculated soil was analyzed through denaturing gradient gel electrophoresis. Results revealed the potential cooperative effect of microbial Fe(III) reduction and sulfate reduction on copper immobilization. After exposure to air for 144 h, more than 50% of the immobilized Cu was remobilized from the anaerobic matrices; aqueous sulfate increased significantly. Sequential extraction analysis demonstrated that the organic matter/sulfide-bound Cu increased by 52% after anaerobic incubation relative to the abiotic treatment but decreased by 32% after oxidation, indicating the generation and oxidation of Cu-sulfide coprecipitates in the inoculated red earth soil. These findings suggest that the immobilization of copper could be enhanced by mediating microbial Fe(III) reduction with sulfate reduction under anaerobic conditions. The findings have an important implication for bioremediation in Cucontaminated and Fe-rich soils, especially in acid-mine-drainage-affected sites. PMID:24448165

Hu, Chaohua; Zhang, Youchi; Zhang, Lei; Luo, Wensui

2014-04-01

208

Effect of chronic ethanol ingestion on the metabolism of copper, iron, manganese, selenium, and zinc in an animal model of alcoholic cardiomyopathy  

SciTech Connect

Alcoholic cardiomyopathy (AC) is one of the diseases caused by alcohol abuse, and there has been considerable debate about the possibility that nutritional factors may be important in the etiology of AC. In addition, there is evidence that ethanol may affect the metabolism of trace elements. The purpose of this investigation was to determine if chronic ethanol administration produces changes in the metabolism of the essential metals copper, iron, manganese, zinc, and selenium using an animal model of AC. Eighteen male Sprague-Dawley rats were divided into three groups; an ad libitum control group (AL), a pair-fed control group (PF), and an ethanol-dosed group (ETOH). The latter group received gradually increasing concentrations (5-25%) of ethanol in the drinking water for 15 wk. Food intake was monitored and urine and feces collected for a 4-d period during the study to determine ethanol effects on trace-element balance. Growth of both the PF and ETOH animals was inhibited. Ethanol produced substantial increases in liver manganese and decreases in liver copper and zinc. Metal concentrations in heart and concentrations in other tissues studied (spleen, testes, brain, bone, kidney, and muscle) did not differ significantly among the groups, except for testes selenium and kidney zinc. Reduced food intake and ethanol ingestion were associated with a reduced percentage of ingested selenium excreted in the urine. Deficiencies of copper, iron, manganese, selenium, and zinc in myocardial tissue are not likely to be involved in the pathogenesis of AC in the rat. 38 references, 1 figure, 4 tables.

Bogden, J.D.; Al-Rabiai, S.; Gilani, S.H.

1984-01-01

209

Semiconducting barium titanate  

Microsoft Academic Search

Barium titanate, which is well known as a basic ferroelectric material, is also of interest when doped because of the interaction between semiconductivity and ferroelectricity. The resistance of blocking layers at surfaces and grain-boundaries is governed mainly by the ferroelectric properties, so that a resistance jump of four decades is observed on heating above the Curie temperature. A survey of

W. Heywang

1971-01-01

210

Influence of aluminum, silicon, and copper on the properties of composite welded joints in an iron base  

Microsoft Academic Search

The properties of welded steel-aluminum joints is governed to a considerable extent by the type of plating preliminarily applied to the steel and the dimensions and character of the diffusion layer produced at the boundary between the iron and molten aluminum [1]. The present investigation completed our study of the influence of alloying Of the iron base on the properties

V. R. Ryabov; V. I. Yumatova

1975-01-01

211

Synthesis of yttrium barium copper oxide-0.325Ag superconductors via intermediate precursor with overall composition Y:Ba:Cu:0=l:2:3:Y, Y>7 produced by high-energy attrition milling  

Microsoft Academic Search

A highly homogeneous composite precursor containing nano-scale particles was synthesized from the highenergy attrition milling\\u000a of a mixture of metallic Y, metallic Cu and barium nitrate (Ba(N03)2) containing 5 wt.% silver. The particle size of the 20 hour attrition-milled precursor was in the range of 30~80 nm as estimated\\u000a by the XRD technique and direct TEM observation. With the heat

Haigun Lee; Dokyol Lee

2000-01-01

212

Growth of highly oriented TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 9{minus}y} superconducting films on Ag substrates using a dip-coated barium calcium copper oxide sol-gel precursor  

SciTech Connect

Thin films of ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 7}, a precursor of TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 9{minus}y}, were prepared by sol-gel synthesis from an all-alkoxide solution. The barium and calcium precursors were the respective metals reacted with 2-methoxyethanol, and the copper precursor was copper methoxide complexed by triethanolamine. Silver substrates were coated using the sol-gel solution by dip-coating. Subsequent processing included a low-temperature drying step (600 C), repeated coating to provide the desired thickness, heat treatment at 850 C in oxygen to remove carbon, and reaction at 860 C in a two-zone thallination furnace to produce a TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 9{minus}y} superconducting film. These films were strongly c-axis-aligned, had a zero-resistance temperature (T{sub c}) of 110 K, and a critical-current density (J{sub c}) of 1.9 {times} 10{sup 4} A/cm{sup 2} at 77 K and zero magnetic field.

Paranthaman, M.; Beach, D.B. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.

1995-09-01

213

Silicosis in barium miners.  

PubMed Central

Four men who mined barytes in Scotland and who developed pneumoconiosis are described. Three developed progressive massive fibrosis, from which two died; and one developed a nodular simple pneumoconiosis after leaving the industry. The radiological and pathological features of the men's lungs were those of silicosis and high proportions of quartz were found in two of them post mortem. The quartz was inhaled from rocks associated with the barytes in the mines. The features of silicosis in barium miners are contrasted with the benign pneumoconiosis, baritosis, that occurs in workers exposed to crushed and ground insoluble barium salts. Diagnostic difficulties arise when silicosis develops in workers mining minerals known to cause a separate and benign pneumoconiosis. These difficulties are compounded when, as not infrequently happens, the silicotic lesions develop or progress after exposure to quartz has ceased. Images PMID:3787542

Seaton, A; Ruckley, V A; Addison, J; Brown, W R

1986-01-01

214

Table of interplanar spacings for crystal-structure determinations by X-ray diffraction with molybdenum, copper, cobalt, iron, and chromium radiations  

NASA Technical Reports Server (NTRS)

For a simple diffraction pattern, the time required to calculate interplanar distances from measurements of the pattern is not excessive. If more than a few lines are present, however, or if several patterns are to be studied, it is very advantageous to have available a table giving interplanar spacings directly in terms of the linear measurements made on the film of the lines appearing on the diffraction pattern. The preparation of the table given here was undertaken when the expansion of research activities involving X-ray diffraction techniques indicated that such a table would greatly decrease the time required to analyze diffraction patterns. The table was prepared for use with K alpha(sub 1) radiation from the following target materials: molybdenum, copper, cobalt, iron, and chromium.

Kittel, J Howard

1945-01-01

215

Comparison of the levels of copper, zinc and iron in cervical mucus and in blood serum of women of childbearing age.  

PubMed

The objective of this research study was a preliminary comparison of some chosen trace elements concentrations in cervical mucus and blood serum of women of childbearing age. The levels of iron (Fe), copper (Cu) and zinc (Zn) were determined in cervical mucus and serum of 10 patients. The obtained results do not point to any association between the levels of the examined trace elements in cervical mucus or any correlation between their contents in mucus and blood serum. As no correlation was found between the blood serum and cervical mucus, as far as trace elements are concerned, one might suggest that the uptake of trace elements by the mucus has an active form. PMID:16145958

Kaczmarek, Andrzej; Robak-Cho?ubek, Dorota; Sowa, Ireneusz; Jakiel, Grzegorz

2004-01-01

216

[Preliminary study of the effect of supplementation of iron, copper, cobalt and zinc on cellulolytic activity in the cecum of the pony].  

PubMed

We studied a caecum-cannulated pony fed hay libitum in order to determine the mineral elements likely to cause deficiencies which decrease microbial activity in the caecum. During four successive 1-month periods, we observed the effects of adding 50 mg of iron, 1 mg of cobalt, 40 mg of copper and 200 mg of zinc, respectively. Except for the introduction of zinc, which greatly diminishes cellulolytic activity measured with the nylon bag technique, there was no significant modification in that activity as shown by pH, NH3-nitrogen, total nitrogen and volatile fatty acid production (table 1). It can be concluded that endogenous secretion in the pre-caecal part of the digestive system of the mineral elements used was sufficient to guarantee good symbiosis between the microbial population of the caecum and the organism. PMID:7349504

Tisserand, J L; Boulard, F; Deponge, P

1980-01-01

217

Properties of Semiconductive Barium Titanates  

Microsoft Academic Search

The resistivity of barium titanate which is usually of the order of 109˜1012 ohm-cm, may be remarkably reduced with suitable control in valency. The valency-controlled barium titanate, whose resistivity is of the order of 10˜104 ohm-cm at room temperature, shows anomalous positive character in the temperature dependency of the resistivity. For example, the resistivity of barium titanate containing 0.1 mol.

Osamu Saburi

1959-01-01

218

Evaluating In-Situ Reactions of Chlorine and Chloramines at the Surface of Copper and Iron using Microelectrodes  

EPA Science Inventory

Corrosion of drinking water plumbing materials is a significant cause of deterioration of treated drinking water quality and a failure to supply safe water to the public. As a result of the Lead and Copper Rule, many water utilities in the US have developed and evaluated corrosio...

219

Temporal trends in the concentration of arsenic, chromium, copper, iron, nickel, vanadium and zinc in mosses across Europe between 1990 and 2000  

NASA Astrophysics Data System (ADS)

The European heavy metals in mosses biomonitoring network provides data on the concentration of 10 heavy metals in naturally growing mosses and is currently coordinated by the UNECE ICP Vegetation (United Nations Economic Commission for Europe International Co-operative Programme on Effects of Air Pollution on Natural Vegetation and Crops). The technique of moss analysis provides a surrogate, time-integrated measure of metal deposition from the atmosphere to terrestrial systems. It is easier and cheaper, less prone to contamination and allows a much higher sampling density than conventional precipitation analysis. Moss surveys have been repeated at five-yearly intervals and in this paper we report on the temporal trends in the concentration of arsenic, chromium, copper, iron, nickel, vanadium and zinc between 1990 and 2000. Maps were produced of the metal concentration in mosses for 1990, 1995 and 2000, showing the mean concentration per metal per 50km×50km EMEP grid square. Metal- and country-specific temporal trends were observed. Although the metal concentration in mosses generally decreased with time for all metals, only the decreases for arsenic, copper, vanadium and zinc were statistically significant. The observed temporal trends were compared with emission trends for Europe reported by EMEP (Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutant in Europe).

Harmens, Harry; Norris, David A.; Koerber, Georgia R.; Buse, Alan; Steinnes, Eiliv; Rühling, Åke

220

Barium isotope fractionation in the global barium cycle: Evidence from barium minerals and precipitation experiments  

NASA Astrophysics Data System (ADS)

In this study, we present first results from an ongoing investigation on the stable barium (Ba) isotope fractionation in the natural barium cycle. Stable Ba isotope signatures of international IAEA reference materials (synthetic barium sulfate and barium carbonate), and terrestrial Ba gangue minerals have been analyzed as a first approach to evaluate potential discriminating processes in the global geochemical barium cycle. Measurements were carried out on a multi-collector ICP-MS applying a 130Ba/135Ba double spike. Data are given as per mil deviations from a laboratory Ba nitrate standard solution in the d137/134Ba notation (external 2s stdev < 0.1 per mil). Whereas the various synthetic solid standards and p.a. quality synthetic barium chloride show very similar isotope results close to the nitrate standard solution, the terrestrial barium gangue minerals (four barites, one norsethite [BaMg(CO3)2]) were depleted in the heavy isotope (d137/134Ba values between 0 and -0.2 per mil). A natural barite, from an unknown Chinese locality, gave an isotope value of -0.4 per mil. Also measured high 34S/32S and 18O/16O ratios in this sample indicate that this barite has been formed under influence of microbial sulfate reduction, probably in a marine diagenetic environment. The observed natural discriminations are by far larger than the analytical uncertainty of the isotope measurements, indicating isotope discrimination in the natural barium cycle. Precipitation experiments from aqueous barium chloride solutions at temperatures of 20° and 80°C indicate that the light Ba isotope is enriched in pure barium carbonate or barium sulfate compared to the aqueous solution. A maximum isotope fractionation of -0.3 per mil is observed, for both barium carbonate and sulfate, that seems to be influenced by precipitation rate (BaCO3) and/or the aqueous speciation, but less by temperature.

von Allmen, Katja; Böttcher, Michael E.; Samankassou, Elias; Nägler, Thomas F.

2010-05-01

221

Formation of nickel and copper ferrites in ceramics: a potential reaction in the reuse of iron-rich sludge incineration ash.  

PubMed

This study investigates potential solid-state reactions for the stabilization of hazardous metals when reusing the incineration ash from chemically enhanced primary treatment (CEPT) sludge to fabricate ceramic products. Nickel and copper were used as examples of hazardous metals, and the iron content in the reaction system was found to play a major role in incorporating these hazardous metals into their ferrite phases (NiFe2O4 and CuFe2O4). The results from three-hour sintering experiments on NiO + Fe2O3 and CuO + Fe2O3 systems clearly demonstrate the potential for initiating metal incorporation mechanisms using an iron-containing precursor at attainable ceramic sintering temperatures (above 750 degrees C). Both ferrite phases were examined using a prolonged leaching experiment modified from the widely used toxicity characteristic leaching procedure (TCLP) to evaluate their long-term metal leachability. The leaching results indicate that both the NiFe2O4 and the CuFe2O4 products were significantly superior to their oxide forms in immobilizing hazardous metals. PMID:23437648

Shih, Kaimin

2012-12-01

222

Calcium, potassium, iron, copper and zinc concentrations in the white and gray matter of the cerebellum and corpus callosum in brain of four genetic mouse strains  

NASA Astrophysics Data System (ADS)

In the central nervous system, metallic cations are involved in oligodendrocyte maturation and myelinogenesis. Moreover, the metallic cations have been associated with pathogenesis, particularly multiple sclerosis and malignant gliomas. The brain is vulnerable to either a deficit or an excess of available trace elements. Relationship between trace metals and myelinogenesis is important in understanding a severe human pathology : the multiple sclerosis, which remains without efficient treatment. One approach to understand this disease has used mutant or transgenic mice presenting myelin deficiency or excess. But to date, the concentration of trace metals and mineral elements in white and gray matter areas in wild type brain is unknown. The aim of this study is to establish the reference concentrations of trace metals (iron, copper and zinc) and minerals (potassium and calcium) in the white and gray matter of the mouse cerebellum and corpus callosum. The brains of four different genetic mouse strains (C57Black6/SJL, C57Black6/D2, SJL and C3H) were analyzed. The freeze-dried samples were prepared to allow PIXE (Proton-induced X-ray emission) and RBS (Rutherford backscattering spectrometry) analyses with the nuclear microprobe in Bordeaux. The results obtained give the first reference values. Furthermore, one species out of the fours testes exhibited differences in calcium, iron and zinc concentrations in the white matter.

Sergeant, C.; Vesvres, M. H.; Devès, G.; Guillou, F.

2005-04-01

223

SOURCES OF COPPER AIR EMISSIONS  

EPA Science Inventory

The report gives results of a study to update estimates of atmospheric emissions of copper and copper compounds in the U.S. Source categories evaluated included: metallic minerals, primary copper smelters, iron and steel making, combustion, municipal incineration, secondary coppe...

224

Barium iron arsenide, barium cobalt arsenide, barium nickel arsenide single crystals and superconductivity upon cobalt doping  

SciTech Connect

The crystal structure and physical properties of BaFe{sub 2}As{sub 2}, BaCo{sub 2}As{sub 2}, and BaNi{sub 2}As{sub 2} single crystals are surveyed. BaFe{sub 2}As{sub 2} gives a magnetic and structural transition at T{sub N} = 132(1) K, BaCo{sub 2}As{sub 2} is a paramagnetic metal, while BaNi{sub 2}As{sub 2} has a structural phase transition at T{sub 0} = 131 K, followed by superconductivity below {Tc} = 0.69 K. The bulk superconductivity in Co-doped BaFe{sub 2}As{sub 2} below {Tc} = 22 K is demonstrated by resistivity, magnetic susceptibility, and specific heat data. In contrast to the cuprates, the Fe-based system appears to tolerate considerable disorder in the transition metal layers. First principles calculations for BaFe{sub 1.84}Co{sub 0.16}As{sub 2} inter-band scattering due to Co is weak.

Ronning, Filip [Los Alamos National Laboratory; Sefat, A S [ORNL; Mcguire, M M [ORNL; Sales, B [ORNL; Jin, R [ORNL; Mandrus, D [ORNL

2009-01-01

225

Copper, iron, zinc, and selenium dietary intake and status of Nepalese lactating women and their breast-fed infants13  

Microsoft Academic Search

The dietary intake ofcopper, iron, zinc, and selenium of26 Nepalese lactat- ing mothers was estimated from chemical analysis of24-h food and beverage composites. Fast- ing blood and milk samples were obtained from the mothers and blood samples were obtained from the infants. The Nepalese mothers consumed significantly more Cu, significantly less Fe and Se, and similar amounts of Zn as

Phylis B Moser; Robert D Reynolds; Suniti Acharya; M Pat Howard; Mark B Andon; Susan A Lewis

226

Changes in Fractions of Iron, Manganese, Copper, and Zinc in Soil under Continuous Cropping for More Than Three Decades  

Microsoft Academic Search

The effect of continuous cropping with maize and wheat on soil characteristics and various forms of micronutrient cations in an Incetisol over the years was studied in an ongoing long?term experiment in New Delhi, India. The soil samples collected in the years of 1993, 1995, 1997, 1999, 2001, 2003, and 2004 were analyzed for different fractions of iron (Fe), manganese

Sanjib Kumar Behera; Dhyan Singh; Brahma Swaroop Dwivedi

2009-01-01

227

Barium uranyl diphosphonates  

SciTech Connect

Three Ba{sup 2+}/UO{sub 2}{sup 2+} methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200 Degree-Sign C. These compounds, Ba[UO{sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{center_dot}1.4H{sub 2}O (Ba-1), Ba{sub 3}[(UO{sub 2}){sub 4}(CH{sub 2}(PO{sub 3}){sub 2}){sub 2}F{sub 6}]{center_dot}6H{sub 2}O (Ba-2), and Ba{sub 2}[(UO{sub 2}){sub 2}(CH{sub 2}(PO{sub 3}){sub 2})F{sub 4}]{center_dot}5.75H{sub 2}O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO{sub 5}F{sub 2} pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO{sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{sup 2-} sheets. The interlayer space of the structures is occupied by Ba{sup 2+}, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance. - Graphical abstract: Illustration of the stacking of the layers in Ba{sub 3}[(UO{sub 2}){sub 4}(CH{sub 2}(PO{sub 3}){sub 2}){sub 2})F{sub 6}]{center_dot}6H{sub 2}O viewed along the c-axis. The structure is constructed from UO{sub 7} pentagonal bipyramidal units, U(1)O{sub 7}=gray, U(2)O{sub 7}=yellow, barium=blue, phosphorus=magenta, fluorine=green, oxygen=red, carbon=black, and hydrogen=light peach. Highlights: Black-Right-Pointing-Pointer The polymerization of the UO{sub 2}{sup 2+} sites to form uranyl dimers leads to structural variations in compounds. Black-Right-Pointing-Pointer Barium cations stitch uranyl diphosphonate anionic layers together, and help mediate structure formation. Black-Right-Pointing-Pointer HF acts as both a mineralizing agent and a ligand.

Nelson, Anna-Gay D., E-mail: nelsoa@umich.edu [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Alekseev, Evgeny V. [Institute of Energy and Climate Research (IEK-6), Forschungszentrum Juelich Wilhelm-Johnen-Strasse, Juelich 52428 (Germany); Ewing, Rodney C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Albrecht-Schmitt, Thomas E. [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

2012-08-15

228

Barium uranyl diphosphonates  

NASA Astrophysics Data System (ADS)

Three Ba2+/UO22+ methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200 °C. These compounds, Ba[UO2[CH2(PO3)2]·1.4H2O (Ba-1), Ba3[(UO2)4(CH2(PO3)2)2F6]·6H2O (Ba-2), and Ba2[(UO2)2(CH2(PO3)2)F4]·5.75H2O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO5F2 pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO2[CH2(PO3)2]2- sheets. The interlayer space of the structures is occupied by Ba2+, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance.

Nelson, Anna-Gay D.; Alekseev, Evgeny V.; Ewing, Rodney C.; Albrecht-Schmitt, Thomas E.

2012-08-01

229

Precipitation and Characterization of Arsenate Phases from Calcium-Copper-Iron-Arsenic Oxide-Sulfate Hydrothermal Systems  

NASA Astrophysics Data System (ADS)

The scope of this thesis is the study of three Fe(III)-As(V) hydrothermal systems. The first one is the Fe(III)-AsO4-SO 4 system and crystalline phases that are produced under high temperature (150-225°C); this was studied to clear up previous contradicting information on this system in relation to industrial arsenic products that are formed during the autoclave processing of arsenical sulphide gold feedstocks and asses their arsenic stability. The second system studied was Cu(II)-Fe(III)-AsO 4-SO4 system at 150°C; this was investigated due to its relevance to industrial pressure leaching of copper concentrates. This system was studied in order to examine the possible effect of copper on the precipitation of scorodite. Finally, the structural and molecular examination of two members of the Ca(II)-Fe(III)-AsO4 system, namely yukonite (synthetic and natural and arseniosiderite was undertaken due to their relatively unknown nature and the potential role play in controlling arsenic release in tailings.

Gomez, Mario Alberto

230

Magnetotelluric evidence for a deep-crustal mineralizing system beneath the Olympic Dam iron oxide copper-gold deposit, southern Australia  

NASA Astrophysics Data System (ADS)

The iron oxide copper-gold Olympic Dam deposit, situated along the margin of the Proterozoic Gawler craton, South Australia, is the world's largest uranium deposit and sixth-largest copper deposit; it also contains significant reserves of gold, silver, and rare earth elements. Gaining a better understanding of the mechanisms for genesis of the economic liberalization is fundamental for defining exploration models in similar crustal settings. To delineate crustal structures that may constrain mineral system fluid pathways, coincident deep crustal seismic and magnetotelluric (MT) transects were obtained along a 220 km section that crosses Olympic Dam and the major crustal boundaries. In this paper we present results from 58 long-period (10 104 s) MT sites, with site spacing of 5 10 km. A two-dimensional inversion of MT data from 33 sites to a depth of 100 km shows four notable features: (1) sedimentary cover sequences with low resistivity (<20 ?·m) thicken to 10 km toward the northern cover sequences of the Adelaide Rift Complex; (2) a northeast-dipping crustal boundary separates a highly resistive (>1000 ?·m) Archean crustal core from a more conductive crust and mantle to the north (typically <500 ?·m); (3) to the north of Olympic Dam, the upper-middle crust to ˜20 km is quite resistive (˜1000 ?·m), but the lower crust is much more conductive (<100 ?·m); and (4) beneath Olympic Dam, we image a low-resistivity region (<100 ?·m) throughout the crust, coincident with a seismically transparent region. We argue that the cause of the low-resistivity and low-reflectivity region beneath Olympic Dam may be due to the upward movement of CO2-bearing volatiles near the time of deposit formation that precipitated conductive graphite liberalization along grain boundaries, simultaneously annihilating acoustic impedance boundaries. The source of the volatiles may be from the mantle degassing or retrograde metamorphism of the lower crust associated with Proterozoic crustal deformation.

Heinson, Graham S.; Direen, Nicholas G.; Gill, Rob M.

2006-07-01

231

A validation of copper, nickel and iron data in endf\\/b-vi.2, jef-2.2 and jendl-3.2 through a series of br-1 critical core analysis  

Microsoft Academic Search

This report discusses the lessons learned from a validation of copper, nickel and iron data in ENDF\\/B-VI.2, JEF-2.2 and JENDL-3.2 through an analysis of 97.6 at. % 239PU metal fueled BR-1 fast reactor benchmarks. The specifications for the benchmarks in this study were taken from the ICSBEP handbook. The Monte Carlo code MCNP4B and continuous-energy cross-section libraries processed from the

Won-Guk Hwang; J KIM; S OH

1998-01-01

232

Single atom barium sources for EXO barium tagging development  

NASA Astrophysics Data System (ADS)

Barium tagging, the extraction and identification of the ^136 Xe double beta decay daughter product, would allow the Enriched Xenon Observatory (EXO) experiment to eliminate almost all backgrounds. The collaboration has made much progress in developing an ion probe to extract a barium ion from either liquid or gas xenon and an ion trap to identify a single barium ion. Yet the true efficiencies of these methods cannot be known until a source of single barium ions is available. I will talk about the Ba source R&D efforts of the EXO collaboration; they include 1) using the alpha recoil of ^148Gd on a thin layer of BaF2, 2) using an electrostatic gate to select single atoms from a Ba ion beam, and 3) using chemistry to isolate ^ 137Cs which then beta decays to Ba^+. )

Yen, Yung-Ruey

2010-02-01

233

Correlations in distribution and concentration of calcium, copper and iron with zinc in isolated extracellular deposits associated with age-related macular degeneration.  

PubMed

Zinc (Zn) is abundantly enriched in sub-retinal pigment epithelial (RPE) deposits, the hallmarks of age-related macular degeneration (AMD), and is thought to play a role in the formation of these deposits. However, it is not known whether Zn is the only metal relevant for sub-RPE deposit formation. Because of their involvement in the pathogenesis of AMD, we determined the concentration and distribution of calcium (Ca), iron (Fe) and copper (Cu) and compared these with Zn in isolated and sectioned macular (MSD), equatorial (PHD) and far peripheral (FPD) sub-RPE deposits from an 86 year old donor eye with post mortem diagnosis of early AMD. The sections were mounted on Zn free microscopy slides and analyzed by microprobe synchrotron X-ray fluorescence (?SXRF). Metal concentrations were determined using spiked sectioned sheep brain matrix standards, prepared the same way as the samples. The heterogeneity of metal distributions was examined using pixel by pixel comparison. The orders of metal concentrations were Ca ? Zn > Fe in all three types of deposits but Cu levels were not distinguishable from background values. Zinc and Ca were consistently present in all deposits but reached highest concentration in MSD. Iron was present in some but not all deposits and was especially enriched in FPD. Correlation analysis indicated considerable variation in metal distribution within and between sub-RPE deposits. The results suggest that Zn and Ca are the most likely contributors to deposit formation especially in MSD, the characteristic risk factor for the development of AMD in the human eye. PMID:24740686

Flinn, Jane M; Kakalec, Peter; Tappero, Ryan; Jones, Blair; Lengyel, Imre

2014-07-01

234

Discovery of the Barium Isotopes  

E-print Network

Thirty-eight barium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

A. Shore; A. Fritsch; J. Q. Ginepro; M. Heim; A. Schuh; M. Thoennessen

2009-08-13

235

Built-Up Films of Barium Stearate and Their Optical Properties  

Microsoft Academic Search

The technique of depositing successive single layers of molecules of various stearates on a solid surface is described. Films containing 3001 layers have been built of barium-copper stearate. A photograph shows films built in a series of steps having intervals of 2 molecular layers. The contrast of the steps is plainly visible when the slide is illuminated by polarized light

Katharine B. Blodgett; Irving Langmuir

1937-01-01

236

Hydrogen bonding of sulfur ligands in blue copper and iron-sulfur proteins: detection by resonance raman spectroscopy  

SciTech Connect

The resonance Raman spectrum of the blue copper protein azurin from Alcaligenes denitrificans exhibits nine vibrational modes between 330 and 460 cm/sup -1/, seven of which shift 0.4-3.0 cm/sup -1/ to lower energy after incubation of the protein in D/sub 2/O. These deuterium-dependent shifts have been previously ascribed to exchangeable protons on imidazole ligands or to exchangeable protons on amide groups which are hydrogen bonded to the cysteine thiolate ligands (a feature common to all blue copper proteins of known structure). In order to distinguish between these two possibilities, a systematic investigation of Fe/sub 2/S/sub 2/(Cys)/sub 4/-containing proteins was undertaken. Extensive hydrogen bonding between sulfur ligands and the polypeptide backbone had been observed in the crystal structure of ferredoxin from Spirulina platensis. The resonance Raman spectrum of this protein is typical of a chloroplast-type ferredoxin and exhibits deuterium-dependent shifts of -0.3 to -0.5 cm/sup -1/ in the Fe-S modes at 283, 367, and 394 cm/sup -1/ and -0.6 to -0.8 cm/sup -1/ in the Fe-S modes at 328 and 341 cm/sup -1/. Considerably greater deuterium sensitivity is observed in the Raman spectra of spinach ferredoxin and bovine adrenodoxin, particularly for the symmetric stretching vibration of the Fe/sub 2/S/sub 2/ moiety at approx. 390 cm/sup -1/. This feature decreases of 9.8 and 1.1 cm/sup -1/, respectively, for the two oxidized proteins in D/sub 2/O and by 1.8 cm/sup -1/ for reduced adrenodoxin in D/sub 2/O. These results suggest that the bridging sulfido groups may be more extensively hydrogen bonded in spinach ferredoxin and adrenodoxin than in S. platensis ferredoxin, with a further increase in hydrogen-bond strength in the reduced form of adrenodoxin.

Mino, Y.; Loehr, T.M.; Wada, K.; Matsubara, H.; Sanders-Loehr, J.

1987-12-15

237

Barium light source method and apparatus  

NASA Technical Reports Server (NTRS)

Visible light emission is obtained from a plasma containing elemental barium including neutral barium atoms and barium ion species. Neutral barium provides a strong green light emission in the center of the visible spectrum with a highly efficient conversion of electrical energy into visible light. By the selective excitation of barium ionic species, emission of visible light at longer and shorter wavelengths can be obtained simultaneously with the green emission from neutral barium, effectively providing light that is visually perceived as white. A discharge vessel contains the elemental barium and a buffer gas fill therein, and a discharge inducer is utilized to induce a desired discharge temperature and barium vapor pressure therein to produce from the barium vapor a visible light emission. The discharge can be induced utilizing a glow discharge between electrodes in the discharge vessel as well as by inductively or capacitively coupling RF energy into the plasma within the discharge vessel.

Curry, John J. (Inventor); MacDonagh-Dumler, Jeffrey (Inventor); Anderson, Heidi M. (Inventor); Lawler, James E. (Inventor)

2002-01-01

238

The Exotic Barium Bismuthates  

NASA Astrophysics Data System (ADS)

We review the remarkable properties, including superconductivity, charge-density-wave ordering and metal-insulator transitions, of lead- and potassium-doped barium bismuthate. We will discuss some of the early theoretical studies of these systems. Our recent theoretical work, on the negative-U, extended-Hubbard model for these systems, will also be described. Both the large- and intermediate-U regimes of this model were examined, using mean-field and random-phase approximations, particularly with a view to fitting various experimental properties of these bismuthates. On the basis of our studies, we point out possibilities for exotic physics in these systems. We also emphasize the different consequences of electronic and phonon-mediated mechanisms for the negative U. We show that, for an electronic mechanism, the semiconducting phases of these bismuthates must be unique, with their transport properties dominated by charge ±2e Cooperon bound states. This can explain the observed difference between the optical and transport gaps. We propose other experimental tests for this novel mechanism of charge transport and comment on the effects of disorder.

Taraphder, A.; Pandit, Rahul; Krishnamurthy, H. R.; Ramakrishnan, T. V.

239

Flame atomic absorption spectrometric (FAAS) determination of copper, iron and zinc in food samples after solid-phase extraction on Schiff base-modified duolite XAD 761.  

PubMed

The present study involves the development of solid-phase extraction (SPE) procedure for the preconcentration of trace amounts of copper (Cu(2+)), iron (Fe(3+)) and zinc (Zn(2+)) ions on duolite XAD 761 modified by bis(2-hydroxyacetophenone)-2,2-dimethyl-1,3-propanediimine(BHAPDMPDI). The complexation between the metal ions and the proposed ligand was investigated potentiometrically. The metal ions retained on the sorbent were quantitatively determined via complexation with BHAPDMPDI. The complexed metal ions were efficiently eluted using 6 mL of 4 mol L(-1) nitric acid in acetone. The influences of the analytical parameters, including pH, amounts of the ligand and the solid phase, eluent conditions and sample volume, on the recoveries of the metal ions were optimized. Using the optimized parameters, the linear response of the SPE method for Cu(2+), Zn(2+) and Fe(3+) ions were in the ranges of 0.01-0.34, 0.01-0.28 and 0.02-0.31 ?g mL(-1), respectively, and the detection limits for Cu(2+), Zn(2+) and Fe(3+) ions were 1.8, 1.6 and 2.4 ?g mL(-1), respectively. The proposed method exhibits a preconcentration factor of 208 for all of the ions studied and an enhancement factor for Cu(2+), Fe(3+) and Zn(2+) ions of 34, 28 and 38, respectively. The presented results demonstrate the successful application of the proposed method for the determination of these metal ions in some real samples with high recoveries (> 95%) and reasonable relative standard deviation (RDS <5%). PMID:23498267

Ghaedi, M; Mortazavi, K; Montazerozohori, M; Shokrollahi, A; Soylak, M

2013-05-01

240

Levels of lead, cadmium, copper, iron, and zinc in deciduous teeth of children living in Irbid, Jordan by ICP-OES: some factors affecting their concentrations.  

PubMed

The aim of this study was to measure the concentrations of lead (Pb), cadmium (Cd), copper (Cu), iron (Fe), and zinc (Zn) in deciduous teeth from children living in Jordan and to investigate the affecting factors. Deciduous teeth samples (n = 320, without fillings) were collected from 5- to 12-year-old children and analyzed for Pb, Cd, Cu, Fe, and Zn using inductively coupled plasma-optical emission spectrometry. A questionnaire was used to gather information on each child, such as sex, age, tooth type (incisors, canines, and molars), tooth position within the mouth (upper or lower jaw), caries status, presence of amalgam fillings inside the mouth, type of drinking water (tap water, home purified water, and plant purified water), and zone of residence (close to or far from heavy traffic roads). The mean concentrations of Pb, Cd, Cu, Fe, and Zn were 30.26, 0.55, 6.23, 34.72, and 128.21 ?g/g, respectively. Our results indicate that there is a clear relation between the concentrations of the metals analyzed in this study and tooth type, tooth position within the mouth, caries status, presence of amalgam fillings inside the mouth, and type of drinking water. No significant differences in the concentrations of the five metals analyzed were observed due to sex. Our results also show that no significant difference among Pb, Cd, Cu, Fe, and Zn concentrations and age among the ages of 5-6, 7-8, 9-10, and 11-12, except for Pb, which decreases at age 11-12. PMID:22851195

Alomary, A; Al-Momani, I F; Obeidat, S M; Massadeh, A M

2013-04-01

241

Opacity of iron, nickel, and copper plasmas in the x-ray wavelength range: Theoretical interpretation of 2p-3d absorption spectra  

SciTech Connect

This paper deals with theoretical studies on the 2p-3d absorption in iron, nickel, and copper plasmas related to LULI2000 (Laboratoire pour l'Utilisation des Lasers Intenses, 2000J facility) measurements in which target temperatures were of the order of 20 eV and plasma densities were in the range 0.004-0.01 g/cm{sup 3}. The radiatively heated targets were close to local thermodynamic equilibrium (LTE). The structure of 2p-3d transitions has been studied with the help of the statistical superconfiguration opacity code sco and with the fine-structure atomic physics codes hullac and fac. A new mixed version of the sco code allowing one to treat part of the configurations by detailed calculation based on the Cowan's code rcg has been also used in these comparisons. Special attention was paid to comparisons between theory and experiment concerning the term features which cannot be reproduced by sco. The differences in the spin-orbit splitting and the statistical (thermal) broadening of the 2p-3d transitions have been investigated as a function of the atomic number Z. It appears that at the conditions of the experiment the role of the term and configuration broadening was different in the three analyzed elements, this broadening being sensitive to the atomic number. Some effects of the temperature gradients and possible non-LTE effects have been studied with the help of the radiative-collisional code scric. The sensitivity of the 2p-3d structures with respect to temperature and density in medium-Z plasmas may be helpful for diagnostics of LTE plasmas especially in future experiments on the {Delta}n=0 absorption in medium-Z plasmas for astrophysical applications.

Blenski, T.; Loisel, G.; Poirier, M.; Thais, F.; Arnault, P.; Caillaud, T.; Fariaut, J.; Gilleron, F.; Pain, J.-C.; Porcherot, Q.; Reverdin, C.; Silvert, V.; Villette, B.; Bastiani-Ceccotti, S.; Turck-Chieze, S.; Foelsner, W.; Gaufridy de Dortan, F. de [CEA, IRAMIS, Service 'Photons, Atomes et Molecules', Centre d'Etudes de Saclay, F-91191 Gif-sur-Yvette Cedex (France); CEA, DAM, DIF, F-91297 Arpajon (France); LULI, UMR No. 7605 CNRS - Ecole Polytechnique, F-91128 Palaiseau Cedex (France); CEA, IRFU, Service d'Astrophysique, Centre d'Etudes de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany); Institute of Nuclear Fusion, Universidad Politecnica de Madrid, Spain and Laboratoire d'Optique Appliquee, ENSTA-Paritech-Polytechnique, Chemin de la Huniere, F-91671 Palaiseau (France)

2011-09-15

242

Relationship of pheasant occurrence to barium in Illinois soils.  

PubMed

Distribution of the ring-necked pheasant (Phasianus colchicus) is nearly co-extensive with the boundary of Wisconsinan glaciation; this is an area of base-rich soils that are mostly developed in calcareous tills. Anderson and Stewart (1973) speculated that barium in the diet might be a factor limiting the pheasant establishment in habitats adjacent to areas of long-term sustaining populations in Illinois. Total Ba was calculated for soils of 74 conterminous counties for which there were pheasant population data. Barium over the range of about 480 to 700 mg kg(-1) soil was unrelated to pheasant occurrence or to population indeces. The selective eating of iron-manganese concretions that are enriched in Ba might present a unique pathway for Ba loading. PMID:24197899

Jones, R L

1992-04-01

243

Barium Stars and Thermohaline Mixing  

SciTech Connect

Barium stars are formed in binary systems through mass transfer from the carbon and s-element rich primary in the AGB phase, to the secondary star which is in a less evolved evolutionary stage. The mixing of the accreted material from the AGB donor with the envelope of the secondary results in a dilution of the s-element abundances. Dilution in red giants is explained by the occurence of the first dredge up, while in case of dwarfs thermohaline mixing would determine it. A comparison between the theoretical predictions of the AGB stellar models and the spectroscopical observations of a large sample of barium stars has been made. Dilution due to thermohaline mixing was taken into account when searching for best fits of the observational data. The importance of thermohaline mixing in barium dwarfs is discussed.

Husti, Laura [Dipartimento di Fisica Generale, Universita di Torino, Via Pietro Giuria 1, 10125 Turin (Italy)

2008-01-24

244

Observations on the histochemistry of barium  

Microsoft Academic Search

The histochemistry of barium was investigated with particular reference to the use of sodium rhodizonate. It was found that not all batches of sodium rhodizonate were able to effect satisfactory visualisation of barium deposits. None of the other histological parameters considered gave a consistent indication of the presence of barium.

A. J. Chaplin; E. L. T. Turner

1983-01-01

245

Refractory concrete based on barium aluminate–barium zirconate cements for steel-making industries  

Microsoft Academic Search

Five refractory cement mixes were prepared from different proportions of barite, zirconia and calcined alumina by sintering at 1500–1550°C for 3h. The obtained cements were composed of barium aluminate and barium zirconate minerals in addition to comparable proportions of di-barium silicate.Cement mix prepared from 70wt.% barite, 10wt.% zirconia and 20wt.% alumina and containing comparable proportions of barium aluminate and barium

N. M. Khalil

2005-01-01

246

Spatial and temporal zoning of hydrothermal alteration and mineralization in the Sossego iron oxide-copper-gold deposit, Carajás Mineral Province, Brazil: paragenesis and stable isotope constraints  

NASA Astrophysics Data System (ADS)

The Sossego iron oxide-copper-gold deposit (245 Mt @ 1.1% Cu, 0.28 g/t Au) in the Carajás Mineral Province of Brazil consists of two major groups of orebodies (Pista-Sequeirinho-Baiano and Sossego-Curral) with distinct alteration assemblages that are separated from each other by a major high angle fault. The deposit is located along a regional WNW-ESE-striking shear zone that defines the contact between metavolcano-sedimentary units of the ˜2.76 Ga Itacaiúnas Supergroup and tonalitic to trondhjemitic gneisses and migmatites of the ˜2.8 Ga Xingu Complex. The deposit is hosted by granite, granophyric granite, gabbro, and felsic metavolcanic rocks. The Pista-Sequeirinho-Baiano orebodies have undergone regional sodic (albite-hematite) alteration and later sodic-calcic (actinolite-rich) alteration associated with the formation of massive magnetite-(apatite) bodies. Both these alteration assemblages display ductile to ductile-brittle fabrics. They are cut by spatially restricted zones of potassic (biotite and potassium feldspar) alteration that grades outward to chlorite-rich assemblages. The Sossego-Curral orebodies contain weakly developed early albitic alteration and very poorly developed subsequent calcic-sodic alteration. These orebodies contain well-developed potassic alteration assemblages that were formed during brittle deformation that resulted in the formation of breccia bodies. Breccia matrix commonly displays coarse mineral infill suggestive of growth into open space. Sulfides in both groups of deposits were precipitated first with potassic alteration and more importantly with a later assemblage of calcite-quartz-epidote-chlorite. In the Sequeirinho orebodies, sulfides range from undeformed to deformed; sulfides in the Sossego-Curral orebodies are undeformed. Very late, weakly mineralized hydrolytic alteration is present in the Sossego/Currral orebodies. The sulfide assemblage is dominated by chalcopyrite with subsidiary siegenite, and millerite. Pyrrhotite and pyrite are minor constituents of ore in the Sequerinho orebodies while pyrite is relatively abundant in the Sossego-Curral bodies. Oxygen isotope partitioning between mineral pairs constrains temperatures in the deposit spatially and through time. In the Sequeirinho orebody, the early sodic-calcic alteration stage was characterized by temperatures exceeding 500°C and ? ^{{{text{18}}}} {text{O}}_{{{text{H}}_{{text{2}}} {text{O}}}} values for the alteration fluid of 6.9 ± 0.9‰. Temperature declines outward and upward from the zone of most intense alteration. Paragenetically later copper-gold mineralization displays markedly lower temperatures (<300°C) and was characterized by the introduction of 18O-depleted hydrothermal fluids -1.8 ± 3.4‰. The calculated ?DH2O and ? ^{{{text{18}}}} {text{O}}_{{{text{H}}_{{text{2}}} {text{O}}}} values suggest that the fluids that formed the early calcic-sodic alteration assemblage were of formational/metamorphic or magmatic origin. The decrease of ? ^{{{text{18}}}} {text{O}}_{{{text{H}}_{{text{2}}} {text{O}}}} values through time may reflect influx of surficially derived waters during later alteration and mineralization events. Influx of such fluids could be related to episodic fluid overpressure, resulting in dilution and cooling of the metalliferous fluid, causing deposition of metals transported as metal chloride complexes.

Monteiro, Lena V. S.; Xavier, Roberto P.; de Carvalho, Emerson R.; Hitzman, Murray W.; Johnson, Craig A.; de Souza Filho, Carlos Roberto; Torresi, Ignácio

2008-02-01

247

Tourmaline B-isotopes fingerprint marine evaporites as the source of high-salinity ore fluids in iron oxide copper-gold deposits, Carajás Mineral Province (Brazil)  

NASA Astrophysics Data System (ADS)

The Carajás Mineral Province in northern Brazil containsa variety of world-class (>100 Mt ore) iron oxide copper-gold(IOCG) deposits, including the only Archean examples of thisdeposit class (e.g., the Igarapé Bahia/Alemãoand Salobo deposits). Tourmaline of schorl-dravite composition,a common gangue mineral in these deposits, precipitated shortlyprior to and after the ore assemblage. A boron isotope studyof texturally different tourmaline from three IOCG deposits(Igarapé Bahia, Salobo, and Sossego) using secondaryion mass spectrometry (SIMS) provides new evidence in the long-standingdebate of magmatic versus non-magmatic sources for the highsalinity (up to 50 wt% NaCl equiv.) of ore fluids in these deposits.Values of {delta}11B from 14{per thousand} to 26.5{per thousand} for the Igarapé Bahia andSalobo deposits confirm marine evaporite-derived brinesin the ore fluids, whereas lower {delta}11B values for the IgarapéBahia deposit (5.8{per thousand} to 8.8{per thousand}) suggest that these fluids may havemixed with an isotopically different hydrothermal fluid, orone that had a mixed boron source. More variable and isotopicallylighter boron in tourmaline from the Sossego deposit (-8{per thousand}to 11{per thousand}) is attributed to mixed sources, including light boronleached from felsic intrusive and volcanic host rocks, and heavyboron derived from marine evaporites. The boron isotope dataindicate that the characteristic high salinity of the ore fluidsin the Carajás Mineral Province was acquired by the interactionof hydrothermal fluids with marine evaporites. For IOCG depositsthat contain tourmaline as a common gangue mineral, boron isotopesoffer a valuable tool to constrain the high-salinity sourceproblem, which is a critical issue in metallogenesis of IOCGdeposits worldwide.

Perez Xavier, Roberto; Wiedenbeck, Michael; Trumbull, Robert B.; Dreher, Ana M.; Monteiro, Lena V. S.; Rhede, Dieter; de Araújo, Carlos E. G.; Torresi, Ignacio

2008-09-01

248

Combined effects of hydrographic structure and iron and copper availability on the phytoplankton growth in Terra Nova Bay Polynya (Ross Sea, Antarctica)  

NASA Astrophysics Data System (ADS)

Surface water (<100 m) samples were collected from the Terra Nova Bay polynya region of the Ross Sea (Antarctica) in January 2006, with the aim of evaluating the individual and combined effects of hydrographic structure, iron and copper concentration and availability on the phytoplankton growth. The measurements were conducted within the framework of the Climatic Long Term Interaction for the Mass-balance in Antarctica (CLIMA) Project of the Programma Nazionale di Ricerca in Antartide activities. Dissolved oxygen, nutrients, phytoplankton pigments and concentration and complexation of dissolved trace metals were determined. Experimental data were elaborated by Principal Component Analysis (PCA). As a result of solar heating and freshwater inputs from melting sea-ice, the water column was strongly stratified with an Upper Mixed Layer 4-16 m deep. The integrated Chl a in the layer 0-100 m ranged from 60 mg m-2 to 235 mg m-2, with a mean value of 138 mg m-2. The pigment analysis showed that diatoms dominated the phytoplankton assemblage. Major nutrients were generally high, with the lowest concentration at the surface and they were never fully depleted. The Si:N drawdown ratio was close to the expected value of 1 for Fe-replete diatoms. We evaluated both the total and the labile dissolved fraction of Fe and Cu. The labile fraction was operationally defined by employing the chelating resin Chelex-100, which retains free and loosely bound trace metal species. The total dissolved Fe ranged from 0.48 to 3.02 nM, while the total dissolved Cu from 3.68 to 6.84 nM. The dissolved labile Fe ranged from below the detection limit (0.15 nM) to 1.22 nM, and the dissolved labile Cu from 0.31 to 1.59 nM, respectively. The labile fractions measured at 20 m were significantly lower than values in 40-100 m samples. As two stations were re-sampled 5 days later, we evaluated the short-term variability of the physical and biogeochemical properties. In particular, in a re-sampled station at 20 m, the total dissolved Fe increased and the total dissolved Cu decreased, while their labile fraction was relatively steady. As a result of the increase in total Fe, the percentage of the labile Fe decreased. An increase of the Si:N, Si:P and Si:FUCO ratios was measured also in the re-sampled station. On this basis, we speculated that a switch from a Fe-replete to a Fe-deplete condition was occurring.

Rivaro, Paola; Luisa Abelmoschi, Maria; Grotti, Marco; Ianni, Carmela; Magi, Emanuele; Margiotta, Francesca; Massolo, Serena; Saggiomo, Vincenzo

2012-04-01

249

Effects of free iron oxyhydrates and soil organic matter on copper sorption-desorption behavior by size fractions of aggregates from two paddy soils.  

PubMed

Effects of free iron oxyhydrates (Fe(d)) and soil organic matter (SOM) on copper (Cu2+) sorption-desorption behavior by size fractions of aggregates from two typical paddy soils (Ferric-Accumulic Stagnic Anthrosol (Soil H) and Gleyic Stagnic Anthrosol (Soil W)) were investigated with and without treatments of dithionite-citrate-bicarbonate and of H2O2. The size fractions of aggregates were obtained from the undisturbed bulk topsoil using a low energy ultrasonic dispersion procedure. Experiments of equilibrium sorption and subsequent desorption were conducted at soil water ratio of 1:20, 25 degrees C. For Soil H, Cu2+ sorption capacity of the DCB-treated size fractions was decreased by 5.9% for fine sand fraction, by 40.4% for coarse sand fraction, in comparison to 2.9% for the bulk sample. However, Cu2+ sorption capacities of the H2O2-treated fractions were decreased by over 80% for the coarse sand fraction and by 15% for the clay-sized fraction in comparison to 88% for bulk soil. For Soil W, Cu2+ sorption capacity of the DCB-treated size fraction was decreased by 30% for the coarse sand fraction and by over 75% for silt sand fraction in comparison to 44.5% for the bulk sample. Cu2+ sorption capacities of the H2O2-treated fractions were decreased by only 2.0% for the coarse sand fraction and by 15% for the fine sand fraction in comparison to by 3.4% for bulk soil. However, Cu2+ desorption rates were increased much in H2O2-treated samples by over 80% except the clay-sized fraction (only 9.5%) for Soil H. While removal of SOM with H2O2 tendend to increase the desorption rate, DCB- and H2O2-treatments caused decrease in Cu2+ retention capacity of size fractions. Particularly, there hardly remained Cu2+ retention capacity by size fractions from Soil H after H2O2 treatment except for clay-sized fraction. These findings supported again the dominance of the coarse sand fraction in sorption of metals and the preference of absorbed metals bound to SOM in differently stabilized status among the size fractions. Thus, enrichment and turnover of SOM in paddy soils may have great effects on metal retention and chemical mobility in paddy soils. PMID:20108663

Wang, Fang; Pan, Genxing; Li, Lianqing

2009-01-01

250

A fungal multicopper oxidase restores iron homeostasis in aceruloplasminemia.  

PubMed

Mutations that lead to a loss of the copper-containing plasma enzyme ceruloplasmin disrupt mammalian iron homeostasis. The mechanism by which ceruloplasmin mobilizes iron from cell stores has been controversial. We demonstrate that injection of a soluble copper-containing yeast protein Fet3p can restore iron homeostasis in phlebotomized mice with a deletion of the ceruloplasmin gene. These results show the conservation of function of copper-containing proteins in eukaryotic iron metabolism. PMID:14739215

Harris, Z Leah; Davis-Kaplan, Sandra R; Gitlin, Jonathan D; Kaplan, Jerry

2004-06-15

251

Copper Test  

MedlinePLUS

... 3. What happens if I am exposed to toxic amounts of copper? Copper poisoning can cause vomiting ... Asked Questions American Cancer Society: Copper Agency for Toxic Substances and Disease Registry: Public Health Statement for ...

252

Identification of iron Superoxide dismutase and a copper\\/zinc Superoxide dismutase enzyme activity within the marine cyanobacterium Synechococcus sp. WH 7803  

Microsoft Academic Search

Three constitutive forms of Superoxide dismutase activity have been demonstrated in the cyanobacterial marine picoplankter Synechococcus sp. WH 7803 using polyacrylamide gel activity staining techniques. A protein which gave a positive non-haem iron stain on native polyacrylamide gels exhibited N-terminal similarity to both the iron Superoxide dismutase and the manganese Superoxide dismutase of Escherichia coli. The metal prosthetic group of

Helen E Chadd; Julie Newman; Nicholas H Mann; Noel G Carr

1996-01-01

253

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

...2014-07-01 false Barium calcium manganese strontium oxide. 721.10011 Section...Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance...substance identified as barium calcium manganese strontium oxide (PMN...

2014-07-01

254

Hydrothermal alteration, fluid inclusions and stable isotope systematics of the Alvo 118 iron oxide-copper-gold deposit, Carajás Mineral Province (Brazil): Implications for ore genesis  

NASA Astrophysics Data System (ADS)

The Alvo 118 iron oxide-copper-gold (IOCG) deposit (170 Mt at 1.0 wt.% Cu, 0.3 g/t Au) lies in the southern sector of the Itacaúnas Shear Belt, Carajás Mineral Province, along a WNW-ESE-striking, 60-km-long shear zone, close to the contact of the ~2.76-Ga metavolcano-sedimentary Itacaiúnas Supergroup and the basement (~3.0 Ga Xingu Complex). The Alvo 118 deposit is hosted by mafic and felsic metavolcanic rocks and crosscutting granitoid and gabbro intrusions that have been subjected to the following hydrothermal alteration sequence towards the ore zones: (1) poorly developed sodic alteration (albite and scapolite); (2) potassic alteration (biotite or K-feldspar) accompanied by magnetite formation and silicification; (3) widespread, pervasive chlorite alteration spatially associated with quartz-carbonate-sulphide infill ore breccia and vein stockworks; and (4) local post-ore quartz-sericite alteration. The ore assemblage is dominated by chalcopyrite (~60%), bornite (~10%), hematite (~20%), magnetite (10%) and subordinate chalcocite, native gold, Au-Ag tellurides, galena, cassiterite, F-rich apatite, xenotime, monazite, britholite-(Y) and a gadolinite-group mineral. Fluid inclusion studies in quartz point to a fluid regime composed of two distinct fluid types that may have probably coexisted within the timeframe of the Cu-Au mineralizing episode: a hot (>200°C) saline (32.8‰ to 40.6 wt.% NaCl eq.) solution, represented by salt-bearing aqueous inclusions, and a lower temperature (<200°C), low to intermediate salinity (<15 wt.% NaCl eq.) aqueous fluid defined by two-phase (LH2O + VH2O) fluid inclusions. This trend is very similar to those defined for other IOCG systems of the Carajás Mineral Province. ? 18OH2O values in equilibrium with calcite (-1.0‰ to 7.5‰ at 277°C to 344°C) overlap the lower range for primary magmatic waters, but the more 18O-depleted values also point to the involvement of externally derived fluids, possibly of meteoric origin. Furthermore, sulphide ? 34S values (5.1‰ to 6.3‰), together with available boron isotope and Cl/Br-Na/Cl data provide evidence for a significant component of residual evaporative fluids (e.g., bittern fluids generated by seawater evaporation) in this scenario that, together with magma-derived brines, would be the main sources of the highly saline fluids involved in the formation Alvo 118 IOCG deposit. The restricted high temperature sodic alteration, the pervasive overprinting of the potassic alteration minerals by chlorite proximal to the ore zones, ore breccias with open-space filling textures in brittle structures, microthermometric and stable isotope data indicate, collectively, that the Alvo 118 IOCG system developed at structurally high levels and may be considered the shallower representative of the IOCG systems of the CMP.

Torresi, Ignacio; Xavier, Roberto Perez; Bortholoto, Diego F. A.; Monteiro, Lena V. S.

2012-03-01

255

Copper in microbial pathogenesis: meddling with the metal  

PubMed Central

Transition metals such as iron, zinc, copper and manganese are essential for the growth and development of organisms ranging from bacteria to mammals. Numerous studies have focused on the impact of iron availability during bacterial and fungal infections, and increasing evidence suggests that copper is also involved in microbial pathogenesis. Not only is copper an essential co-factor for specific microbial enzymes, but several recent studies also strongly suggest that copper is used to restrict pathogen growth in vivo. Here, we review evidence that animals use copper as an anti-microbial weapon and, in turn, microbes have developed mechanisms to counteract the toxic effects of copper. PMID:22341460

Samanovic, Marie I.; Ding, Chen; Thiele, Dennis J.; Darwin, K. Heran

2012-01-01

256

Method for harvesting rare earth barium copper oxide single crystals  

DOEpatents

A method of preparing high temperature superconductor single crystals. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid.

Todt, Volker R. (Lemont, IL); Sengupta, Suvankar (Columbus, OH); Shi, Donglu (Cincinnati, OH)

1996-01-01

257

Method for harvesting rare earth barium copper oxide single crystals  

DOEpatents

A method of preparing high temperature superconductor single crystals is disclosed. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid. 2 figs.

Todt, V.R.; Sengupta, S.; Shi, D.

1996-04-02

258

Improved spectrophotometric analysis of barium styphnate  

Microsoft Academic Search

A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and in styphnic acid. Our investigation has shown that the molar absorptivity and lambda maxima of the styphnate

N. E. Brown; J. A. Blasi

1983-01-01

259

Improved spectrophotometric analysis of barium styphnate  

Microsoft Academic Search

A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and styphnic acid at pH 6.8. Our investigation has shown that the molar absorptivities and maxima of the

Norman E. Brown; Jane A. Blasi

1985-01-01

260

Barium granuloma of the transverse colon.  

PubMed Central

A case of barium sulphate granuloma of the transverse colon following gunshot wounds to the abdomen has been described. Scanning electron microscopy with electron probe microanalysis was used to confirm the presence of barium sulphate and the absence of lead or other elements related to the gunshot wounds. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:740599

McKee, P. H.; Cameron, C. H.

1978-01-01

261

REMOVAL OF BARIUM AND RADIUM FROM GROUNDWATER  

EPA Science Inventory

A research project was undertaken to investigate processes for removing barium and radium from drinking water. Special emphasis was placed on ion exchange processes that can be used without adding large concentrations of sodium to the water. The wastes from radium and barium remo...

262

Gene Cluster of Rhodothermus marinus High-Potential Iron-Sulfur Protein:Oxygen Oxidoreductase, a caa3-Type Oxidase Belonging to the Superfamily of Heme-Copper Oxidases  

PubMed Central

The respiratory chain of the thermohalophilic bacterium Rhodothermus marinus contains an oxygen reductase, which uses HiPIP (high potential iron-sulfur protein) as an electron donor. The structural genes encoding the four subunits of this HiPIP:oxygen oxidoreductase were cloned and sequenced. The genes for subunits II, I, III, and IV (named rcoxA to rcoxD) are found in this order and seemed to be organized in an operon of at least five genes with a terminator structure a few nucleotides downstream of rcoxD. Examination of the amino acid sequence of the Rcox subunits shows that the subunits of the R. marinus enzyme have homology to the corresponding subunits of oxidases belonging to the superfamily of heme-copper oxidases. RcoxB has the conserved histidines involved in binding the binuclear center and the low-spin heme. All of the residues proposed to be involved in proton transfer channels are conserved, with the exception of the key glutamate residue of the D-channel (E278, Paracoccus denitrificans numbering). Analysis of the homology-derived structural model of subunit I shows that the phenol group of a tyrosine (Y) residue and the hydroxyl group of the following serine (S) may functionally substitute the glutamate carboxyl in proton transfer. RcoxA has an additional sequence for heme C binding, after the CuA domain, that is characteristic of caa3 oxidases belonging to the superfamily. Homology modeling of the structure of this cytochrome domain of subunit II shows no marked electrostatic character, especially around the heme edge region, suggesting that the interaction with a redox partner is not of an electrostatic nature. This observation is analyzed in relation to the electron donor for this caa3 oxidase, the HiPIP. In conclusion, it is shown that an oxidase, which uses an iron-sulfur protein as an electron donor, is structurally related to the caa3 class of heme-copper cytochrome c oxidases. The data are discussed in the framework of the evolution of oxidases within the superfamily of heme-copper oxidases. PMID:11133964

Santana, Margarida; Pereira, Manuela M.; Elias, Nuno P.; Soares, Claudio M.; Teixeira, Miguel

2001-01-01

263

Synergistic effects of added bivalent aqua cobalt ion, bivalent aqua iron ion and aqueous sulfurous acid on a graphite anode during electrodeposition of copper from a sulfate bath  

Microsoft Academic Search

The individual as well as the synergistic effect of depolarisers, such as H2SO3 (aq) and\\/or Fe2+ (aq) and\\/or Co2+ (aq) on copper electrodeposition has been studied. A comparison is made of their relative effects on anode potential, cell potential, current efficiency (CE), power consumption and deposit quality. Linear sweep voltammetry (LSV) has been used to study the cathodic and the

Bijayalaxmi Panda; S. C Das; R. K Panda

2004-01-01

264

Acute barium nitrate intoxication treated by hemodialysis.  

PubMed

A 22-year-old male was admitted to hospital with diarrhea and vomiting, cardiac arrhythmias, severe hypokalemia and gradual onset of muscular weakness. A potassium infusion was started, but for several hours serum potassium remained low. Evidence of toxic ingestion was initially lacking. When it became clear -- after a considerable delay -- that the patient had ingested barium nitrate, hemodialysis was started. This resulted in rapid clinical improvement with correction of hypokalemia and restored muscular function. Intoxication with barium causes hypokalemia, arrhythmias, muscular weakness and paralysis, often requiring respiratory support. This patient presented with symptoms typical of severe barium intoxication, non-responsive to potassium supplementation. There are few published reports on the use of hemodialysis in barium poisoning. This case confirms the possible benefit of hemodialysis in severe cases, where potassium supplementation alone is insufficient. PMID:15675995

Bahlmann, H; Lindwall, R; Persson, H

2005-01-01

265

Barium Isotopes in Single Presolar Grains  

NASA Technical Reports Server (NTRS)

Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

2001-01-01

266

Small barium rail gun for plasma injection.  

PubMed

A small rail gun with a barium electrode can be operated at higher than one shot per second to produce more than 2x10(16) barium ions with energy 10-20 eV. The operation of the gun takes advantage of the external magnetic field for cross-field plasma injection into a trap. Up to 7 kG of the magnetic field examined, the gun performance improves with the increased magnetic field strength. PMID:18647050

Kiwamoto, Y

1980-03-01

267

Thermochemical hydrogen production via a cycle using barium and sulfur - Reaction between barium sulfide and water  

NASA Technical Reports Server (NTRS)

The reaction between barium sulfide and water, a reaction found in several sulfur based thermochemical cycles, was investigated kinetically at 653-866 C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. An expression was derived for the rate of hydrogen formation.

Ota, K.; Conger, W. L.

1977-01-01

268

Sulphate removal from sodium sulphate-rich brine and recovery of barium as a barium salt mixture.  

PubMed

Sulphate removal from sodium sulphate-rich brine using barium hydroxide and recovery of the barium salts has been investigated. The sodium sulphate-rich brine treated with different dosages of barium hydroxide to precipitate barium sulphate showed sulphate removal from 13.5 g/L to less than 400 mg/L over 60 min using a barium to sulphate molar ratio of 1.1. The thermal conversion of precipitated barium sulphate to barium sulphide achieved a conversion yield of 85% using coal as both a reducing agent and an energy source. The recovery of a pure mixture of barium salts from barium sulphide, which involved dissolution of barium sulphide and reaction with ammonium hydroxide resulted in recovery of a mixture of barium carbonate (62%) and barium hydroxide (38%), which is a critical input raw material for barium salts based acid mine drainage (AMD) desalination technologies. Under alkaline conditions of this barium salt mixture recovery process, ammonia gas is given off, while hydrogen sulfide is retained in solution as bisulfide species, and this provides basis for ammonium hydroxide separation and recovery for reuse, with hydrogen sulfide also recoverable for further industrial applications such as sulfur production by subsequent stripping. PMID:23485244

Vadapalli, Viswanath R K; Zvimba, John N; Mulopo, Jean; Motaung, Solly

2013-01-01

269

Iron and Iron Deficiency  

MedlinePLUS

... other types of foods eaten at the same meal. Foods containing heme iron (meat, poultry, and fish) ... heme iron absorption when eaten at the same meal. Substances (such as polyphenols, phytates, or calcium) that ...

270

Copper slag thermal storage -- projections of performance and economics  

Microsoft Academic Search

A solid residual regarded as waste from copper smelters, known as copper slag, offers an excellent medium for the storage of heat energy. Over one billion tons of slag is available at hundreds of smelters around the world. Copper slag is predominantly iron orthosilicate (2FeO.SiOâ), with sizable amounts of calcium, aluminum, magnesium and copper oxides. Formed in a highly oxidized

Curto

1984-01-01

271

Adaptation of Aerobically Growing Pseudomonas aeruginosa to Copper Starvation  

Microsoft Academic Search

Restricted bioavailability of copper in certain environments can interfere with cellular respiration because copper is an essential cofactor of most terminal oxidases. The global response of the metabolically versatile bacterium and opportunistic pathogen Pseudomonas aeruginosa to copper limitation was assessed under aerobic conditions. Expression of cioAB (encoding an alternative, copper-independent, cyanide-resistant ubiquinol oxidase) was upregulated, whereas numerous iron uptake functions

Emanuela Frangipani; Vera I. Slaveykova; Cornelia Reimmann; Dieter Haas

2008-01-01

272

Direct Production of Copper  

NASA Astrophysics Data System (ADS)

The use of commercially pure oxygen in flash smelting a typical chalcopyrite concentrate or a low grade comminuted matte directly to copper produces a large excess of heat. The heat balance is controlled by adjusting the calorific value of the solid feed. A portion of the sulfide material is roasted to produce a calcine which is blended with unroasted material, and the blend is then autogeneously smelted with oxygen and flux directly to copper. Either iron silicate or iron calcareous slags are produced, both being subject to a slag cleaning treatment. Practically all of the sulfur is contained in a continuous stream of SO2 gas, most of which is strong enough for liquefaction. A particularly attractive feature of these technologies is that no radically new metallurgical equipment needs to be developed. The oxygen smelting can be carried out not only in the Inco type flash furnace but in other suitable smelters such as cyclone furnaces. Another major advantage stems from abolishion of the ever-troublesome converter aisle, which is replaced with continuous roasting of a fraction of the copper sulfide feed.

Victorovich, G. S.; Bell, M. C.; Diaz, C. M.; Bell, J. A. E.

1987-09-01

273

Copper and oxidative stress in the pathogenesis of Alzheimer's disease.  

PubMed

Copper is a redox-active metal with many important biological roles. Consequently, its distribution and oxidation state are subject to stringent regulation. A large body of clinicopathological, circumstantial, and epidemiological evidence suggests that the dysregulation of copper is intimately involved in the pathogenesis of Alzheimer's disease. Other light transition metals such as iron and zinc may affect copper regulation by competing for copper binding sites and transporters. Therapeutic interventions targeting the regulation of copper are promising, but large gaps in our understanding of copper biochemistry, amyloidogenesis, and the nature of oxidative stress in the brain must be addressed. PMID:22708607

Eskici, Gözde; Axelsen, Paul H

2012-08-14

274

Determination of calcium, copper, iron, magnesium, manganese, potassium, phosphorus, sodium, and zinc in fortified food products by microwave digestion and inductively coupled plasma-optical emission spectrometry: single-laboratory validation and ring trial.  

PubMed

A single-laboratory validation (SLV) and a ring trial (RT) were undertaken to determine nine nutritional elements in food products by inductively coupled plasma-optical emission spectrometry in order to modernize AOAC Official Method 984.27. The improvements involved extension of the scope to all food matrixes (including infant formula), optimized microwave digestion, selected analytical lines, internal standardization, and ion buffering. Simultaneous determination of nine elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc) was made in food products. Sample digestion was performed through wet digestion of food samples by microwave technology with either closed- or open-vessel systems. Validation was performed to characterize the method for selectivity, sensitivity, linearity, accuracy, precision, recovery, ruggedness, and uncertainty. The robustness and efficiency of this method was proven through a successful RT using experienced independent food industry laboratories. Performance characteristics are reported for 13 certified and in-house reference materials, populating the AOAC triangle food sectors, which fulfilled AOAC criteria and recommendations for accuracy (trueness, recovery, and z-scores) and precision (repeatability and reproducibility RSD, and HorRat values) regarding SLVs and RTs. This multielemental method is cost-efficient, time-saving, accurate, and fit-for-purpose according to ISO 17025 Norm and AOAC acceptability criteria, and is proposed as an extended updated version of AOAC Official Method 984.27 for fortified food products, including infant formula. PMID:22468357

Poitevin, Eric

2012-01-01

275

Seasonal variability in cadmium, lead, copper, zinc and iron concentrations in the three major fish species, Oreochromis niloticus, Lates niloticus and Rastrineobola argentea in Winam Gulf, Lake Victoria: impact of wash-off into the lake.  

PubMed

Trace metals Cadmium (Cd), Lead (Pb), Copper (Cu), Zinc (Zn) and Iron (Fe) were analyzed in edible portions of three main finfish species namely Lates niloticus, Oreochromis niloticus and Rastrineobola argentea sampled from various beaches of Winam Gulf, Lake Victoria, Kenya, in order to determine any seasonal and site variations and the results showed significantly (p < 0.05) higher mean concentrations of Cd, Cu, Zn and Fe during the wet season compared to the dry season for all the three species indicating the impact of wash-off into the lake during the rainy periods. The overall mean concentrations of the heavy metals (in ?g/g dry weight) in all combined samples ranged from 0.17-0.40 (Cd), 0.47-2.53 (Pb), 2.13-8.74 (Cu), 28.9-409.3 (Zn) and 31.4-208.1 (Fe), respectively. It was found that consumption of Rastrineobola argentea can be a significant source of heavy metals especially Zn, to humans, compared with Lates niloticus and Oreochromis niloticus, if only the muscle parts of the latter two are consumed. PMID:22130608

Ongeri, David M K; Lalah, Joseph O; Wandiga, Shem O; Schramm, Karl-Werner; Michalke, Bernard

2012-02-01

276

Electrodeposition of titania and barium titanate thin films for high dielectric applications  

NASA Astrophysics Data System (ADS)

In order to address the requirement of a low-temperature low-cost cost processing for depositing high dielectric constant ceramic films for applications in embedded capacitor and flexible electronics technology, two different chemical bath processes, namely, thermohydrolytic deposition (TD) and cathodic electrodeposition (ED) have been exploited to generate titania thin films. In thermohydrolytic deposition technique, titania films were generated from acidic aqueous solution of titanium chloride on F: SnO2 coated glass and Si substrates by temperature assisted hydrolysis mechanism. On the other hand, in cathodic electrodeposition, in-situ electro-generation of hydroxyl ions triggered a fast deposition of titania on conductive substrates such as copper and F: SnO2 coated glass from peroxotitanium solution at low temperatures (˜0°C). In both techniques, solution compositions affected the morphology and crystallinity of the films. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques have been employed to perform such characterization. As both processes utilized water as solvent, the as-deposited films contained hydroxyl ligand or physically adsorbed water molecules in the titania layer. Besides that, electrodeposited films contained peroxotitanium bonds which were characterized by FTIR studies. Although as-electrodeposited titania films were X-ray amorphous, considerable crystallinity could be generated by heat treatment. The films obtained from both the processes showed v moderately high dielectric constant (ranging from 9-30 at 100 kHz) and high breakdown voltage (0.09-0.15 MV/cm) in electrical measurements. To further improve the dielectric constant, electrodeposited titania films were converted to barium titanate films in high pH barium ion containing solution at 80-90°C. The resultant film contained cubic crystalline barium titanate verified by XRD analysis. Simple low-temperature hydrothermal technique of conversion worked perfect for F:SnO2 coated glass substrates, but in this process, high pH precursor caused corrosion in copper substrates and deposition of copper oxide in the final films. To overcome this, an innovative technique, which incorporates an electrochemical protection of substrates by application of cathodic potential in addition to common hydrothermal conversion, has been adopted. Films generated by common hydrothermal technique on F:SnO 2/glass substrates and via electrochemical-hydrothermal technique on Cu substrates showed promising dielectric behavior. Apart from the experimental studies, this report also includes various thermodynamic studies related to hydrolysis and precipitation of titanium ion, protection of copper during titania deposition and barium titanate conversion. Gibbs free energy based model and speciation studies were used to understand supersaturation which is a controlling factor in thermohydrolytic deposition. Similar approaches were utilized to understand the possibilities of barium titanate formation at different Ba2+ concentrations with different pH conditions. Possibilities of atmospheric carbon dioxide incorporation to generate barium carbonate instead of barium titanate formation were also determined by mathematical calculations. Whenever relevant, results of such theoretical analysis were utilized to design the experiment or to explain the experimental observations.

Roy, Biplab Kumar

277

Improved spectrophotometric analysis of barium styphnate  

SciTech Connect

A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and in styphnic acid. Our investigation has shown that the molar absorptivity and lambda maxima of the styphnate ion are quite pH dependent; therefore, the pH is buffered to 6.8 to 7.0 with ammonium acetate. Under these conditions the molar absorptivity is 1.6 x 10/sup 4/ L/mol-cm. Analyses following the procedure in the Navy specification WS13444A using water were found to give low molar absorptivities (1.3 x 10/sup 4/ L/mol-cm) for the styphnic acid calibration resulting in erroneous values for barium styphnate purity.

Brown, N E; Blasi, J A

1983-01-01

278

Dispersion strengthened copper  

DOEpatents

A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

Sheinberg, Haskell (Los Alamos, NM); Meek, Thomas T. (Knoxville, TN); Blake, Rodger D. (Santa Fe, NM)

1990-01-01

279

Dispersion strengthened copper  

DOEpatents

A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

Sheinberg, Haskell (Los Alamos, NM); Meek, Thomas T. (Knoxville, TN); Blake, Rodger D. (Santa Fe, NM)

1989-01-01

280

CARBONATION OF BARIUM SULFIDE IN A FOAM-BED REACTOR  

Microsoft Academic Search

Carbonation of barium sulfide to barium carbonate has been experimentally investigated in a foam-bed reactor. The variables studied are height of foam bed, initial concentration of barium sulfide in aqueous solution, gas flow rate, concentration of carbon dioxide in mixture with nitrogen, and surfactant concentration in the aqueous solution. The results indicate that the conversion in the reactor increases with

Amit A. Gaikwad; Niyantha Challapalli; Ashok N. Bhaskarwar

2010-01-01

281

Occupational Exposure to Welding Fume among Welders: Alterations of Manganese, Iron, Zinc, Copper, and Lead in Body Fluids and the Oxidative Stress Status  

PubMed Central

Welders in this study were selected from a vehicle manufacturer; control subjects were from a nearby food factory. Airborne manganese levels in the breathing zones of welders and controls were 1.45 ± SD1.08 mg/m3 and 0.11 ± 0.07 ?g/m3, respectively. Serum levels of manganese and iron in welders were 4.3-fold and 1.9-fold, respectively, higher than those of controls. Blood lead concentrations in welders increased 2.5-fold, whereas serum zinc levels decreased 1.2-fold, in comparison with controls. Linear regression revealed the lack of associations between blood levels of five metals and welder’s age. Furthermore, welders had erythrocytic superoxide dismutase activity and serum malondialdehyde levels 24% less and 78% higher, respectively, than those of controls. These findings suggest that occupational exposure to welding fumes among welders disturbs the homeostasis of trace elements in systemic circulation and induces oxidative stress. PMID:15091287

Li, Guojun Jane; Zhang, Long-Lian; Lu, Ling; Wu, Ping; Zheng, Wei

2014-01-01

282

Improved Spectrophotometric Analysis of Barium Styphnate.  

National Technical Information Service (NTIS)

A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in bari...

J. A. Blasi, N. E. Brown

1983-01-01

283

Barium Additives As Diesel Smoke Suppressants  

Microsoft Academic Search

The body of information presented in this paper is directed to those individuals concerned with the emission of smoke from diesel engines. A series of tests was performed on a Petter Type AA1 diesel engine using barium smoke suppressant additives. An Andersen cascade type sampler was used to collect samples and thus study the effect of the additive upon the

C. David Turley; David L. Brenchley; Robert R. Landolt

1973-01-01

284

Observations on a Fully Ionized Barium Plasma  

Microsoft Academic Search

A series of spectroscopic measurements in a fully ionized barium plasma column is described and discussed. The plasma was generated in the Q-1 device in a manner similar to that used to make alkali-metal plasmas. The observations show that the density contours and the temperature profiles in the body of the plasma were strongly influenced by conditions at the end

N. Rynn; E. Hinnov; L. C. Johnson

1965-01-01

285

Quantum manipulation on the Barium quadrupolar transition  

E-print Network

and stabilization of a new fiber laser system to ma- nipulate the Barium quadrupolar transition, with the aim . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3 Trapped ion coupled to a laser field 18 3.1 Light-matter interaction . . . . . . . . . . . . . . . 55 6 Spectroscopy and sideband cooling on a single 138 Ba+ 58 6.1 Quantum jumps using the fiber laser . . . . . . . . . . . . .

Blatt, Rainer

286

Strength and toughness of barium titanate ceramics  

Microsoft Academic Search

The effect of processing variables on the mechanical and electrical properties of holmium-doped barium titanate ceramics with a positive temperature coefficient of resistance has been investigated. This paper contains details of the tests used to measure the mechanical properties of ceramics prepared using four compositional mixes. Two methods of measuring strength were used: diametral compression of disc samples and four-point

J. M. Blamey; T. V. Parry

1993-01-01

287

Remanence, self-demagnetization and their ramifications for magnetic modelling of iron oxide copper-gold deposits: An example from Candelaria, Chile  

NASA Astrophysics Data System (ADS)

Magnetic modelling can be a powerful tool for understanding the architecture of numerous types of mineralized systems; e.g., iron ore, IOCG and porphyry deposits. In such modelling, the induced component is generally assumed to be dominant, whereas remanent magnetization is often neglected and, furthermore, the effects of self-demagnetization are commonly ignored. We present rock property measurements (magnetic susceptibility and remanent magnetization) from the Candelaria IOCG deposit in northern Chile. The results demonstrate that remanence is relatively weak (< 20% of induced) and that the causative lithologies have very high magnetic susceptibilities (3-4 SI), which makes them highly prone to self-demagnetization. The rock property results were used to constrain a simplified forward model in which the causative bodies are modelled as a series of sub-horizontal highly magnetic sheets, corresponding to “mantos”. These “mantos” occur north and south of Candelaria, sub-perpendicular to a splay off the Atacama Fault Zone. We demonstrate that Candelaria's unusual magnetic anomaly is due to a combination of its highly magnetic sub-horizontal architecture, and self-demagnetization effects. A further simplified model was used to calculate two synthetic anomalies, one ignoring and the other incorporating the self-demagnetization effect. These synthetic anomalies demonstrate that the magnetic anomaly amplitude is suppressed by up to approximately 50% at Candelaria due to self-demagnetization, and that the induced magnetization is also slightly rotated from the regional inducing field towards the plane of the “mantos”. The dominant paleomagnetic component recorded by the Candelaria deposit and host rocks is a normal polarity remanence of moderate to high stability which is interpreted to have been acquired during the mid-Cretaceous alteration and mineralisation event(s) that generated the magnetic minerals (predominantly magnetite). However, the presence of a reversed polarity overprint component in some samples suggests that the Candelaria deposit and its immediate environs have experienced a post 83 Ma thermal or thermochemical event that has not been previously recognised. The remanence directions of both polarities are rotated clockwise with respect to the expected directions for mid-Cretaceous/Early Tertiary fields, indicating clockwise rotation of the Candelaria area, including the adjacent batholith, through at least 45° since the acquisition of the normal and reversed remanence components, i.e. since 83 Ma. This case study illustrates the importance of understanding the magnetic behaviour of different ore types, and incorporating self-demagnetization into modelling procedures for highly magnetic targets in mineral exploration.

Austin, James; Geuna, Silvana; Clark, David; Hillan, Dean

2014-10-01

288

Degradation of the holmium-barium-copper oxide superconductor, HoBa{sub 2}Cu{sub 3}O{sub 6.92}, under the action of H{sub 2}O and D{sub 2}O: A study by the radiothermoluminescence method  

SciTech Connect

Information about the existence of impurities and defects on the surfaces of high-T{sub c} superconductors (HTSC) can be obtained by radiothermoluminescence (RTL). The degradation of HTSC materials results from their interaction with water and CO{sub 2}. It has been established that the intensity of RTL is very insignificant for freshly prepared HTSC or for samples stored in a dry atmosphere. However, a large increase in RTL intensity occurs if specimens are in contact with water. Barium hydroxide, carbonate, and oxides make the largest contribution to RTL of superconducting ceramics with degraded surfaces. The RTL curves for Ba(OH){sub 2} and BaCO{sub 3} differ slightly from each other, which makes it difficult to estimate the contribution of each of them to the luminescence observed.

Lotnik, S.V.; Khamidullina, L.A.; Korobeinikova, V.N. [Institute of Organic Chemistry, Oktyabrya (Russian Federation)] [and others

1994-12-01

289

Research of semi solid casting of iron  

Microsoft Academic Search

One result of the research on semi solid casting of iron is the development of parts having qualities that combine the superior material properties of ferrous alloy with the dimensional accuracy of aluminum die-cast parts. Iron material composition, molding methods using optimal billet heating speeds and copper die materials and methods for the continuous casting of raw material billets were

Masayuki Tsuchiya; Hiroaki Ueno; Isamu Takagi

2003-01-01

290

Copper staves in the blast furnace  

SciTech Connect

Operational data for stave cooling systems for two German blast furnaces show good correlation with predicted thermal results. Copper staves have been installed in blast furnaces in the zones exposed to the highest thermal loads. The good operational results achieved confirm the choice of copper staves in the areas of maximum heat load. Both temperature measurements and predictions establish that the MAN GHH copper staves do not experience large temperature fluctuations and that the hot face temperatures will be below 250 F. This suggests that the copper staves maintain a more stable accretion layer than the cast iron staves. Contrary to initial expectations, heat flux to the copper staves is 50% lower than that to cast iron staves. The more stable accretion layer acts as an excellent insulator for the stave and greatly reduces the number of times the hot face of the stave is exposed to the blast furnace process and should result in a more stable furnace operation. In the future, it may be unnecessary to use high quality, expensive refractories in front of copper staves because of the highly stable accretion layer that appears to rapidly form due to the lower operating temperature of the staves. There is a balance of application regions for cast iron and copper staves that minimizes the capital cost of a blast furnace reline and provides an integrated cooling system with multiple campaign life potential. Cast iron staves are proven cooling elements that are capable of multiple campaign life in areas of the blast furnace which do not experience extreme heat loads. Copper staves are proving to be an effective and reliable blast furnace cooling element that are subject to virtually no wear and are projected to have a longer campaign service life in the areas of highest thermal load in the blast furnace.

Helenbrook, R.G. [ATSI, Inc., Amherst, NY (United States); Kowalski, W. [Thyssen Stahl AG, Duisburg (Germany); Grosspietsch, K.H. [Preussag Stahl AG, Saltzgitter (Germany); Hille, H. [MAN GHH AG, Oberhausen (Germany)

1996-08-01

291

LABORATORY EXPERIMENT 7 The Iodometric Determination of Copper in Brass  

E-print Network

LABORATORY EXPERIMENT 7 The Iodometric Determination of Copper in Brass Discussion The method is relatively simple and applicable to brasses with less than 2% iron. A weighed sample is treated with nitric

Nazarenko, Alexander

292

ARE THERE ANY STARS LACKING NEUTRON-CAPTURE ELEMENTS? EVIDENCE FROM STRONTIUM AND BARIUM  

SciTech Connect

The cosmic dispersion in the abundances of the heavy elements strontium and barium in halo stars is well known. Strontium and barium are detected in most cool, metal-poor giants, but are these elements always detectable? To identify stars that could be considered probable candidates for lacking these elements, I examine the stellar abundance data available in the literature for 1148 field stars and 226 stars in dwarf galaxies, 776 of which have metallicities lower than [Fe/H] <-2.0. Strontium or barium have been detected in all field, globular cluster, and dwarf galaxy environments studied. All upper limits are consistent with the lowest detected ratios of [Sr/H] and [Ba/H]. The frequent appearance of these elements raises the intriguing prospect that at least one kind of neutron-capture reaction operates as often as the nucleosynthesis mechanisms that produce lighter elements, such as magnesium, calcium, or iron, although the yields of heavy elements may be more variable.

Roederer, Ian U., E-mail: iur@obs.carnegiescience.edu [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2013-01-01

293

Pathogenic adaptations to host-derived antibacterial copper  

PubMed Central

Recent findings suggest that both host and pathogen manipulate copper content in infected host niches during infections. In this review, we summarize recent developments that implicate copper resistance as an important determinant of bacterial fitness at the host-pathogen interface. An essential mammalian nutrient, copper cycles between copper (I) (Cu+) in its reduced form and copper (II) (Cu2+) in its oxidized form under physiologic conditions. Cu+ is significantly more bactericidal than Cu2+ due to its ability to freely penetrate bacterial membranes and inactivate intracellular iron-sulfur clusters. Copper ions can also catalyze reactive oxygen species (ROS) generation, which may further contribute to their toxicity. Transporters, chaperones, redox proteins, receptors and transcription factors and even siderophores affect copper accumulation and distribution in both pathogenic microbes and their human hosts. This review will briefly cover evidence for copper as a mammalian antibacterial effector, the possible reasons for this toxicity, and pathogenic resistance mechanisms directed against it. PMID:24551598

Chaturvedi, Kaveri S.; Henderson, Jeffrey P.

2014-01-01

294

Iron, transferrin and myelinogenesis  

NASA Astrophysics Data System (ADS)

Transferrin (Tf), the iron binding protein of vertebrates serum, is known to be synthesized by oligodendrocytes (Ols) in the central nervous system. It has been postulated that Tf is involved in Ols maturation and myelinogenesis. This link is particularly important in the understanding of a severe human pathology: the multiple sclerosis, which remains without efficient treatment. We generated transgenic mice containing the complete human Tf gene and extensive regulatory sequences from the 5 ' and 3 ' untranslated regions that specifically overexpress Tf in Ols. Brain cytoarchitecture of the transgenic mice appears to be normal in all brain regions examined, total myelin content is increased by 30% and motor coordination is significantly improved when compared with non-transgenic littermates. Tf role in the central nervous system may be related to its affinity for metallic cations. Normal and transgenic mice were used for determination of trace metals (iron, copper and zinc) and minerals (potassium and calcium) concentration in cerebellum and corpus callosum. The freeze-dried samples were prepared to allow proton-induced X-ray emission and Rutherford backscattering spectrometry analyses with the nuclear microprobe in Bordeaux. Preliminary results were obtained and carbon distribution was revealed as a very good analysis to distinguish precisely the white matter region. A comparison of metallic and mineral elements contents in brain between normal and transgenic mice shows that iron, copper and zinc levels remained constant. This result provides evidence that effects of Tf overexpression in the brain do not solely relate to iron transport.

Sergeant, C.; Vesvres, M. H.; Devès, G.; Baron, B.; Guillou, F.

2003-09-01

295

High toughness-high strength iron alloy  

NASA Technical Reports Server (NTRS)

An iron alloy is provided which exhibits strength and toughness characteristics at cryogenic temperatures. The alloy consists essentially of about 10 to 16 percent by weight nickel, about 0.1 to 1.0 percent by weight aluminum, and 0 to about 3 percent by weight copper, with the balance being essentially iron. The iron alloy is produced by a process which includes cold rolling at room temperature and subsequent heat treatment.

Stephens, J. R.; Witzke, W. R. (inventors)

1980-01-01

296

Physico-chemical properties of copper electrorefining and electrowinning electrolytes  

NASA Astrophysics Data System (ADS)

Densities, viscosities, electrical conductivities and specific heats of solutions containing copper, nickel, arsenic, iron and sulphuric acid in the concentration ranges of copper electrorefining and electrowinning electrolytes have been measured. Equations are presented for calculating these properties as a function of electrolyte composition and temperature.

Price, Derek C.; Davenport, William G.

1981-12-01

297

Physicochemical properties of copper electrorefining and electrowinning electrolytes  

Microsoft Academic Search

Densities, viscosities, electrical conductivities and specific heats of solutions containing copper, nickel, arsenic, iron\\u000a and sulphuric acid in the concentration ranges of copper electrorefining and electrowinning electrolytes have been measured.\\u000a Equations are presented for calculating these properties as a function of electrolyte composition and temperature.

Derek C. Price; William G. Davenport

1981-01-01

298

Gaseous calcium, strontium, and barium phosphites  

Microsoft Academic Search

The authors investigated the composition of the vapor over calcium, strontium, and barium orthophosphates in the temperature range of 1900-2500°K. The study was carried out on an MS-1301 mass spectrometer; the vaporization was carried out from molybdenum Knudsen chambers. The heating was carried out by electron bombardment, and the temperature was measured with an EOP-66 optical pyrometer. The ions Me\\/sup

S. I. Lopatin; G. A. Semenov

1986-01-01

299

Prospects for Barium Tagging in Gaseous Xenon  

NASA Astrophysics Data System (ADS)

Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the Ba++ can be efficiently converted to Ba+ as required for laser identification.

Sinclair, D.; Rollin, E.; Smith, J.; Mommers, A.; Ackeran, N.; Aharmin, B.; Auger, M.; Barbeau, P. S.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Cook, S.; Coppens, A.; Daniels, T.; DeVoe, R.; Dobi, A.; Dolinski, M. J.; Donato, K.; Fairbank, W., Jr.; Farine, J.; Giroux, G.; Gornea, G.; Graham, K.; Gratta, G.; Green, M.; Hagemann, C.; Hall, C.; Hall, K.; Hallman, D.; Hargrove, C.; Herrin, S.; Kaufman, L. K.; Leonard, D. S.; LePort, F.; Mackay, D.; MacLennan, R.; Mong, B.; Montero Díez, M.; Müller, A. R.; Neilson, R.; Niner, E.; Odian, A.; O'Sullivan, K.; Ouellet, C.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Pushkin, K.; Rowson, P. C.; Slutsky, S.; Stekhanov, V.; Twelker, K.; Voskanian, N.; Vuilleumier, J.-L.; Wichoski, U.; Wodin, J.; Yang, L.; Yen, Y.-R.

2011-08-01

300

Iron and Mechanisms of Neurotoxicity  

PubMed Central

The accumulation of transition metals (e.g., copper, zinc, and iron) and the dysregulation of their metabolism are a hallmark in the pathogenesis of several neurodegenerative diseases. This paper will be focused on the mechanism of neurotoxicity mediated by iron. This metal progressively accumulates in the brain both during normal aging and neurodegenerative processes. High iron concentrations in the brain have been consistently observed in Alzheimer's (AD) and Parkinson's (PD) diseases. In this connection, metalloneurobiology has become extremely important in establishing the role of iron in the onset and progression of neurodegenerative diseases. Neurons have developed several protective mechanisms against oxidative stress, among them, the activation of cellular signaling pathways. The final response will depend on the identity, intensity, and persistence of the oxidative insult. The characterization of the mechanisms mediating the effects of iron-induced increase in neuronal dysfunction and death is central to understanding the pathology of a number of neurodegenerative disorders. PMID:21234369

Salvador, Gabriela A.; Uranga, Romina M.; Giusto, Norma M.

2011-01-01

301

Prolonged Intraocular Pressure Reduction Following Intravitreal Barium Injection in Rabbits  

Microsoft Academic Search

The isolated ciliary epithelium contains barium-inhibitable potassium channels. The present study was aimed at testing the in vivo effects of barium on aqueous humor dynamics in rabbits. BaCl2was administered to one eye by topical delivery or intravitreal injection. Dynamic measurements included intraocular pressure, outflow facility, episcleral venous pressure and aqueous flow (fluorophotometry). Barium dynamics were studied using133Ba. Intraocular pressure was

THEODORE KRUPIN; ABBAS HYDERI; DIANE KARALEKAS; MARK J. FRITZ

1996-01-01

302

Exclusion of copper from altered hepatocytes in white perch (Morone americana) with hepatic copper storage.  

PubMed

Iron is excluded from foci of hepatocellular alteration in carcinogenesis of rodents and some fish. Among white perch (Morone americana), there is a condition of hepatic copper storage in which copper-loaded livers are produced naturally. In a group of fish collected from the Chesapeake Bay, Maryland (USA), from September to December 1990, we observed hepatic lesions which excluded copper similar to the phenomenon of iron exclusion, in a white perch with over 3,600 micrograms/g wet weight hepatic copper. The lesions were of two types: one with cells morphologically different from normal hepatocytes and which had diminished to absolute exclusion of copper with the copper specific histochemical stain rubeinic acid, and a second with cells morphologically similar to normal hepatocytes which had only a partial exclusion of copper. Although the exact cause and nature of the lesions was not determined, intrinsic copper toxicity, environmental pollution, or a combination of these factors may have contributed to their development. PMID:7563436

Bunton, T E

1995-01-01

303

The effect of zinc methionine or copper lysine on stocker calves grazing oat pastures  

E-print Network

for growth and the prevention of anemia in rats since 1928 (Hart et al. , 1928). Many 12 experiments soon followed providing evidence of copper's essentiality for growth and prevention of a wide range of clinical and pathological disorders in many... in swine when 250 ppm copper as copper sulfate was added. The high level of copper can lead to anemia, copper toxicity, or zinc deficiency unless the diets contain adequate iron and zinc as antagonists. One hundred and fifty ppm of both iron and zinc can...

Griffeth, Laura Ann

2012-06-07

304

Accumulation and hyperaccumulation of copper in plants  

NASA Astrophysics Data System (ADS)

Copper is natural component of our environment. Flow of copper(II) ions in the environment depends on solubility of compounds containing this metal. Mobile ion coming from soil and rocks due to volcanic activity, rains and others are then distributed to water. Bio-availability of copper is substantially lower than its concentration in the aquatic environment. Copper present in the water reacts with other compounds and creates a complex, not available for organisms. The availability of copper varies depending on the environment, but moving around within the range from 5 to 25 % of total copper. Thus copper is stored in the sediments and the rest is transported to the seas and oceans. It is common knowledge that copper is essential element for most living organisms. For this reason this element is actively accumulated in the tissues. The total quantity of copper in soil ranges from 2 to 250 mg / kg, the average concentration is 30 mg / kg. Certain activities related to agriculture (the use of fungicides), possibly with the metallurgical industry and mining, tend to increase the total quantity of copper in the soil. This amount of copper in the soil is a problem particularly for agricultural production of food. The lack of copper causes a decrease in revenue and reduction in quality of production. In Europe, shows the low level of copper in total 18 million hectares of farmland. To remedy this adverse situation is the increasing use of copper fertilizers in agricultural soils. It is known that copper compounds are used in plant protection against various illnesses and pests. Mining of minerals is for the development of human society a key economic activity. An important site where the copper is mined in the Slovakia is nearby Smolníka. Due to long time mining in his area (more than 700 years) there are places with extremely high concentrations of various metals including copper. Besides copper, there are also detected iron, zinc and arsenic. Various plant species have adapted on such stress. The aim of this study is to investigate the behaviour of copper in plants and to assess its potential effect on the surrounding environment. To detect copper in biological samples electrochemical methods were employed particularly differential pulse voltammetry (DPV). Copper gave signals at 0.02 V measured by DPV. The obtained calibration dependence was linear (R2 = 0.995). Further, this method was utilized for determination of copper in real soil samples obtained from previously mentioned heavy-metal-polluted mining area. The content varied within range from tens to hundreds of mg of copper per kg of the soil. Moreover, we focused on investigation of copper influence on seedlings of Norway spruce. The seedlings were treated with copper (0, 0.1, 10 and 100 mM) for four weeks. We observed anatomical-morphological changes and other biochemical parameters in plants. We determined that seedlings synthesized more than 48 % protective thiols (glutathione and phytochelatins) compared to control ones. We investigated copper distribution in plant tissues by diphenylcarbazide staining. We found out that copper is highly accumulated in parenchymal stalk cells. In needles, change in auto-fluorescence of parenchymal cells of mesoderm similarly to endodermis cells. Besides, we analyzed samples of plants from the polluted area (spruce, pin, birch). The data obtained well correlated with previously mentioned. Acknowledgement The work on this experiment was supported by grant: INCHEMBIOL MSM0021622412.

Adam, V.; Trnkova, L.; Huska, D.; Babula, P.; Kizek, R.

2009-04-01

305

Creating unstable velocity-space distributions with barium injections  

NASA Technical Reports Server (NTRS)

Ion velocity-space distributions resulting from barium injections from orbiting spacecraft and shaped charges are discussed. Active experiments confirm that anomalous ionization processes may operate, but photoionization accounts for the production of the bulk of the barium ions. Pitch-angle diffusion and/or velocity-space diffusion may occur, but observations of barium ions moving upwards against gravity suggests that the ions retain a significant enough fraction of their initial perpendicular velocity to provide a mirror force. The barium ion plasmas should have a range of Alfven Mach numbers and plasma betas. Because the initial conditions can be predicted these active experiments should permit testing plasma instability hypotheses.

Pongratz, M. B.

1983-01-01

306

Effects of barium concentration on oropharyngeal swallow timing measures.  

PubMed

Videofluoroscopy is commonly used for evaluating oropharyngeal swallowing but requires radiopaque contrast (typically barium). Prior studies suggest that some aspects of swallowing, including timing measures of oral and pharyngeal bolus transit, vary depending on barium concentration. The aim of our study was to identify timing differences in healthy swallowing between "thin" (40 % w/v concentration) and "ultrathin" (22 % w/v concentration) barium solutions. Twenty healthy adults (Ten women; mean age = 31 years) each performed a series of three noncued 5-ml swallows each of ultrathin and thin liquid barium solutions in videofluoroscopy. Timing measures were compared between barium concentrations using a mixed-model ANOVA. The measures of interest were stage transition duration, pharyngeal transit time, and duration of upper esophageal sphincter opening. Significant differences were observed in the timing measures of swallowing with respect to barium concentration. In all cases, longer durations were seen with the higher barium concentration. Barium concentration influences timing parameters in healthy swallowing, even between ultrathin and thin concentrations. Clinicians need to understand and control for the impact of different barium stimuli on swallowing physiology. PMID:24045851

Stokely, Shauna L; Molfenter, Sonja M; Steele, Catriona M

2014-02-01

307

Microbial iron management mechanisms in extremely acidic environments: comparative genomics evidence for diversity and versatility  

Microsoft Academic Search

BACKGROUND: Iron is an essential nutrient but can be toxic at high intracellular concentrations and organisms have evolved tightly regulated mechanisms for iron uptake and homeostasis. Information on iron management mechanisms is available for organisms living at circumneutral pH. However, very little is known about how acidophilic bacteria, especially those used for industrial copper bioleaching, cope with environmental iron loads

Héctor Osorio; Verónica Martínez; Pamela A Nieto; David S Holmes; Raquel Quatrini

2008-01-01

308

Effect of 3d-transition metal doping on the shielding behavior of barium borate glasses: A spectroscopic study  

NASA Astrophysics Data System (ADS)

UV-visible and FT infrared spectra were measured for prepared samples before and after gamma irradiation. Base undoped barium borate glass of the basic composition (BaO 40%-B2O3 60 mol.%) reveals strong charge transfer UV absorption bands which are related to unavoidable trace iron impurities (Fe3+) within the chemical raw materials. 3d transition metal (TM)-doped glasses exhibit extra characteristic absorption bands due to each TM in its specific valence or coordinate state. The optical spectra show that TM ions favor generally the presence in the high valence or tetrahedral coordination state in barium borate host glass. Infrared absorption bands of all prepared glasses reveal the appearance of both triangular BO3 units and tetrahedral BO4 units within their characteristic vibrational modes and the TM-ions cause minor effects because of the low doping level introduced (0.2%). Gamma irradiation of the undoped barium borate glass increases the intensity of the UV absorption together with the generation of an induced broad visible band at about 580 nm. These changes are correlated with suggested photochemical reactions of trace iron impurities together with the generation of positive hole center (BHC or OHC) within the visible region through generated electrons and positive holes during the irradiation process.

ElBatal, H. A.; Abdelghany, A. M.; Ghoneim, N. A.; ElBatal, F. H.

2014-12-01

309

Copper Cleanup  

NSDL National Science Digital Library

In this hands-on experiment, kids use chemistry to explore whether acids or bases are better at restoring a pennyâs shine. Kids follow the scientific process to test a common household cleaning products alongside ketchup, cola, and other kitchen staples, and may be surprised by the results! A downloadable data sheet is available on the Copper Cleanup activity resources page.

Wgbh

2010-01-01

310

Oxidation Potentials in Matte Smelting of Copper and Nickel  

NASA Astrophysics Data System (ADS)

The oxidation potential, given as the base-ten logarithm of the oxygen partial pressure in bars and the temperature [log pO2/ T, °C], defines the state of oxidation of pyrometallurgical extraction and refining processes. This property varies from copper making, [-6/1150]; to lead/zinc smelting, [-10/1200]; to iron smelting, [-13/1600]. The current article extends the analysis to the smelting of copper and nickel/copper sulfide concentrates to produce mattes of the type Cu(Ni)FeS(O) and iron silicate slags, FeOxSiO2—with oxidation potentials of [-7.5/1250].

Matousek, Jan W.

2014-09-01

311

Survival and Growth in the Presence of Elevated Copper: Transcriptional Profiling of Copper-Stressed Pseudomonas aeruginosa†  

PubMed Central

Transcriptional profiles of Pseudomonas aeruginosa exposed to two separate copper stress conditions were determined. Actively growing bacteria subjected to a pulse of elevated copper for a short period of time was defined as a “copper-shocked” culture. Conversely, copper-adapted populations were defined as cells actively growing in the presence of elevated copper. Expression of 405 genes changed in the copper-shocked culture, compared to 331 genes for the copper-adapted cultures. Not surprisingly, there were genes identified in common to both conditions. For example, both stress conditions resulted in up-regulation of genes encoding several active transport functions. However, there were some interesting differences between the two types of stress. Only copper-adapted cells significantly altered expression of passive transport functions, down-regulating expression of several porins belonging to the OprD family. Copper shock produced expression profiles suggestive of an oxidative stress response, probably due to the participation of copper in Fenton-like chemistry. Copper-adapted populations did not show such a response. Transcriptional profiles also indicated that iron acquisition is fine-tuned in the presence of copper. Several genes induced under iron-limiting conditions, such as the siderophore pyoverdine, were up-regulated in copper-adapted populations. Interesting exceptions were the genes involved in the production of the siderophore pyochelin, which were down-regulated. Analysis of the copper sensitivity of select mutant strains confirmed the array data. These studies suggest that two resistance nodulation division efflux systems, a P-type ATPase, and a two-component regulator were particularly important for copper tolerance in P. aeruginosa. PMID:17015663

Teitzel, Gail M.; Geddie, Ashley; De Long, Susan K.; Kirisits, Mary Jo; Whiteley, Marvin; Parsek, Matthew R.

2006-01-01

312

Investigation of Conventional- and Induction-Sintered Iron and Iron-Based Powder Metal Compacts  

NASA Astrophysics Data System (ADS)

Induction sintering was developed as an alternative method to conventional sintering to sinter iron-based powder metal (PM) compacts. Several compositions of compact such as pure iron, 3 wt.% copper mixed iron, or 3 wt.% bronze mixed iron were sintered by using induction sintering machines with 12 kW power and 30 kHz frequency. The mechanical properties, microstructural properties, densities, and microhardness values were investigated for both processes. Iron-based PM compacts sintered at 1120°C by induction in 8.33 min (500 s) were found to be similar to those sintered conventionally in 30 min. The results were compared with the experimental studies.

Çavdar, U?ur; Atik, Enver

2014-06-01

313

Iron and Copper in Mitochondrial Diseases  

PubMed Central

Summary Transition metals are frequently used as co-factors for enzymes and oxygen-carrying proteins that take advantage of their propensity to gain and lose single electrons. Metals are particularly important in mitochondria, where they play essential roles in the production of ATP and detoxification of reactive oxygen species. At the same time, transition metals (particularly Fe and Cu) can promote the formation of harmful radicals, necessitating meticulous control of metal concentration and subcellular compartmentalization. We summarize our current understanding of Fe and Cu in mammalian mitochondrial biology, and discuss human diseases associated with aberrations in mitochondrial metal homeostasis. PMID:23473029

Xu, Wenjing; Barrientos, Tomasa; Andrews, Nancy C.

2013-01-01

314

Investigation of magnetic properties in the case of three families of 1-dimensional magnets: M(II)A(4,4'-bipyridine); M = iron, cobalt, nickel, copper; A = chloride, nitrogen, (ox)  

NASA Astrophysics Data System (ADS)

Magnetic properties of three families of metal-organic coordinated networks which have the general form of M(II)A(4,4'-bipyridine), where M=Fe, Ni, Co, and Cu and A=Cl2, (ox) and (N3)2, are studied in this dissertation. Novel Ni(N3)2(4,4'-bipyridine), Co(N3)2(4,4'-bipyridine) and Cu(N 3)2(4,4'-bipyridine) have been synthesized. We applied different synthesis procedures and produced Ni, Co, and Cu azide compounds for the first time, thus leaving the hydrothermal route procedure. Powder x-ray diffraction at room temperature was done in order to establish the crystal structure of the members of these three families. It was found that all of them crystallize in orthorhombic structure, where transitional metals have an octahedral coordination. Since all three families have identical crystal structure we got opportunity to examine how ligands facilitate magnetic interaction between metallic centers and also to test existing magnetic theoretical models. Since 4,4'-bipyridine is much longer than other ligands, our systems can be considered as 1-D magnetic systems. Their interchain magnetic interactions are very weak, and they order magnetically at very low temperatures of the order of few K. Measurements of M(H) at temperatures T=1.9K and T=2K and chi(T) in different external magnetic fields in zero field and field cooled modes have been made. In the case of MCl2(4,4'-bipyridine) family of compounds, we observed ferromagnetic interactions between metal ions within the chains and antiferromagnetic interactions between adjacent chains. M(ox)(4,4'-bipyridine) family of metal-organic compounds has antiferromagnetic interactions between the transitional metal ions within the chain, while weak ferromagnetic interaction exists between the chains. All members in the M(N3)2(4,4'-bipyridine) family except in the case of the copper compound were found to have ferromagnetic interactions between metal ions within the chains and then antiferromagnetic interactions between adjacent chains. The copper compound does not show magnetic ordering in the temperature range we considered. All the metal ions in these compounds were detected in high spin states. The magnetic susceptibility data was fit to appropriate 1-D models, which in the case of MCl2(4,4'-bipyridine) and M(N3)2(4,4'-bipyridine) were the Classical Spin Fisher model, and the Bonner Fisher model in the case M(ox)(4,4'-bipyridine). The experimental results and fitting to the appropriate model with the accuracy of 0.995 suggests that shorter Cl-M-Cl distances facilitate ferromagnetic interactions, which are more sensitive to the total spin value then to the sole distance between metal ions. The magnetic behavior of M(N3) 2(4,4'-bipyridine) family of coordinated metal-organic compounds is very interesting because family members exhibit both ferromagnetic and antiferromagnetic behavior. The ferromagnetic characteristics decrease with decreasing spin. Fitting the results for all compounds of the M(ox)(4,4'-bipyridine) family have shown that strong anisotropy exists in all of them, being highest in Ni(ox)(4,'4-bipyridine) and lowest in Co(ox)(4,4'-bipyridine). Specific heat measurements were performed in the case of cobalt and copper azide compounds and then compared with previously obtained results for the iron coordinated network of the same family. Although none of these compounds show the characteristic lambda shaped transition indicating magnetic ordering, all of them have unusually large values of the constant gamma, which indicates significant magnetic contribution to the observed specific heat, since the free electron contribution in these observed families is negligible. We have concluded that total spin of the transitional metal plays a more important role than the distance between ions within the chain in determining magnitude of interaction, and that (N3)2 is a better facilitator of ferromagnetic interaction between ions than Cl2.

Danilovic, Dusan S.

315

Migration and escape of barium atoms in a thermionic cathode  

Microsoft Academic Search

A quantitative study of the physical processes on a thermionic cathode that are crucial to both cathode life and noise are investigated. Of particular interest are the transport of the barium atoms from the cathode interior to the cathode surface and beyond. To investigate these physical processes, a model of barium migration to the surface and its subsequent removal by

Kevin L. Jensen; Y. Y. Lau; B. Levush

2000-01-01

316

PHOTOSENSITIVE CENTERS AND CHARGE TRANSFER PROCESSES IN BARIUM CALCIUM TITANATE  

E-print Network

PHOTOSENSITIVE CENTERS AND CHARGE TRANSFER PROCESSES IN BARIUM CALCIUM TITANATE G.MALOVICHKO, V calcium titanate crystals, Ba0.77Ca0.23TiO3, in the temperature range between 4.2 K and 300 K are reported of crystals from barium titanate (BT) family make them promising candidates for various applications

Malovichko, Galina

317

Barium Tagging for the Enriched Xenon Observatory (EXO)  

NASA Astrophysics Data System (ADS)

The EXO experiment is designed to search for zero-neutrino double beta decay of the isotope Xe^136, in order to better understand the nature of neutrinos. Since the daughter of this decay is barium (Ba^136), detecting the presence of Ba^136 at a decay site (called ``barium tagging'') is the best way to reject backgrounds in the search for this decay. It is hopeful that barium tagging will be implemented in the next phase of EXO. One proposed barium tagging method is to trap the barium ion in a solid xenon matrix (by freezing the liquid xenon surrounding the decay), and move it to another location to do laser-induced fluorescence spectroscopy counting. Our group at CSU is researching the detection of single barium ions and atoms within a solid xenon matrix. A barium ion beam is used to implant the ions into freezing xenon, where laser spectroscopy is then performed. We demonstrate successful detection of very small numbers, and are nearing single-barium detection.

Walton, Timothy

2012-10-01

318

Cardiotoxic and bronchoconstrictor effects of industrial metal fumes containing barium.  

PubMed

For certain metal arc-welding and other metal processing operations, compounds of barium are used as flux components. Airborne fumes generated by welding with electrodes using barium fluoride or carbonate fluxes may contain 15-30% of barium in readily water-soluble form (Dare et al. 1984). Urine of welders inhaling such fumes was shown to contain elevated levels of barium ions (up to 234 micrograms/l). To assess the possible hazards of such exposure, the toxic potencies of fume samples, expressed in terms of their water-soluble barium ion contents, were compared with effects of solutions of barium salts in anaesthetised guinea-pigs. Dose-effect relationships were established and it was verified that acute toxic effects of inhaled aerosols or of intravenous bolus administration correlated with the barium contents of various forms of welding fumes. Bronchopulmonary reactivity to the barium was observed as marked increases in resistance to ventilatory air-flow, indicating bronchoconstriction. Simultaneously, marked pressor effects on blood pressure occurred. ECG abnormalities indicated myocardial hyperexcitability. Effects were modified by nifedipine and propranolol pretreatments. PMID:3468925

Hicks, R; Caldas, L Q; Dare, P R; Hewitt, P J

1986-01-01

319

Experiments with remote entanglement using single barium ions Nathan Kurz  

E-print Network

Experiments with remote entanglement using single barium ions Nathan Kurz A dissertation submitted This is to certify that I have examined this copy of a doctoral dissertation by Nathan Kurz and have found entanglement using single barium ions Nathan Kurz Chair of the Supervisory Committee: Dr. Boris B. Blinov

Blinov, Boris

320

Barium strontium titanate powder obtained by polymeric precursor method  

SciTech Connect

Pure barium strontium titanate powder, with Ba/Sr ratio of 80/20 was prepared by the polymeric precursor method (also called Pechini process). The powder was obtained after a calcination at 800 deg. C for 8 h and characterized by XRD, IR, BET and SEM. The requirements to avoid barium carbonate as a secondary phase are presented and discussed in detail.

Ries, A.; Simoes, A.Z.; Cilense, M.; Zaghete, M.A.; Varela, J.A

2003-03-15

321

Current-voltage characteristics of barium polymethacrylate  

SciTech Connect

In this paper current-voltage characteristics of Barium Polymethacrylate (BaPMA) in the form of Al-BaPMA-Al structures are studied. The currents are measured in the voltage range 10 V-1 kV. At low voltages an ohmic relation is observed and at higher voltages the Poole-Frenkel mechanism is proposed. The mechanism of conduction has been explained on the basis of different current-voltage and current-temperature curves. The activation energy values calculated using Arrhenius relation fall in the range 0.25-2 eV, suggesting a sequence of trapping levels.

Chohan, M.H. (Lab. for Electrical Characterization of Polymers, Dept. of Electronics, Quaid-i-Azam Univ., Islamabad (PK)); Zulfiqar, M.; Sapra, Z.H.; Husain, R.; Zulfiqar, S. (Dept. of Chemistry, Quaid-i-Azam Univ., Islamabad (PK))

1992-06-30

322

Barium dierbium(III) tetra-sulfide.  

PubMed

Barium dierbium(III) tetra-sulfide, BaEr2S4, crystallizes with four formula units in the ortho-rhom-bic space group Pnma in the CaFe2O4 structure type. The asymmetric unit contains two Er, one Ba, and four S atoms, each with .m. site symmetry. The structure consists of channels formed by corner- and edge-sharing ErS6 octa-hedra in which Ba atoms reside. The resultant coordination of Ba is that of a bicapped trigonal prism. PMID:23476480

Mesbah, Adel; Stojko, Wojciech; Ibers, James A

2013-03-01

323

Barium dierbium(III) tetra-sulfide  

PubMed Central

Barium dierbium(III) tetra­sulfide, BaEr2S4, crystallizes with four formula units in the ortho­rhom­bic space group Pnma in the CaFe2O4 structure type. The asymmetric unit contains two Er, one Ba, and four S atoms, each with .m. site symmetry. The structure consists of channels formed by corner- and edge-sharing ErS6 octa­hedra in which Ba atoms reside. The resultant coordination of Ba is that of a bicapped trigonal prism. PMID:23476480

Mesbah, Adel; Stojko, Wojciech; Ibers, James. A

2013-01-01

324

Europium-doped barium bromide iodide  

SciTech Connect

Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

2009-10-21

325

Dielectric properties of barium titanate supramolecular nanocomposites.  

PubMed

Nanostructured dielectric composites can be obtained by dispersing high permittivity fillers, barium titanate (BTO) nanocubes, within a supramolecular framework. Thin films of BTO supramolecular nanocomposites exhibit a dielectric permittivity (?r) as high as 15 and a relatively low dielectric loss of ?0.1 at 1 kHz. These results demonstrate a new route to control the dispersion of high permittivity fillers toward high permittivity dielectric nanocomposites with low loss. Furthermore, the present study shows that the size distribution of nanofillers plays a key role in their spatial distribution and local ordering and alignment within supramolecular nanostructures. PMID:24584569

Lee, Keun Hyung; Kao, Joseph; Parizi, Saman Salemizadeh; Caruntu, Gabriel; Xu, Ting

2014-04-01

326

Production of translationally cold barium monohalide ions  

NASA Astrophysics Data System (ADS)

We have produced sympathetically cooled barium monohalide ions BaX+ (X=F, Cl, Br) by reacting trapped, laser-cooled Ba+ ions with room-temperature gas-phase neutral halogen-containing molecules. Reaction rates for two of these (SF6 and CH3Cl) have been measured and were found to be in agreement with classical models. BaX+ ions are promising candidates for cooling to the rovibrational ground state, and our method presents a straightforward way to produce these polar molecular ions.

DePalatis, M. V.; Chapman, M. S.

2013-08-01

327

Short-cavity squeezing in barium  

NASA Technical Reports Server (NTRS)

Broadband phase sensitive noise and squeezing were experimentally observed in a system of barium atoms interacting with a single mode of a short optical cavity. Squeezing of 13 +/- 3 percent was observed. A maximum possible squeezing of 45 +/- 8 percent could be inferred for out experimental conditions, after correction for measured loss factors. Noise reductions below the quantum limit were found over a range of detection frequencies 60-170 MHz and were best for high cavity transmission and large optical depths. The amount of squeezing observed is consistent with theoretical predictions from a full quantum statistical model of the system.

Hope, D. M.; Bachor, H-A.; Manson, P. J.; Mcclelland, D. E.

1992-01-01

328

Copper peroxide  

NASA Technical Reports Server (NTRS)

A number of oxidizing agents, including chlorine, bromine, ozone and other peroxides, were allowed to act on copper solutions with the intention of forming copper peroxide. The only successful agent appears to be hydrogen peroxide. It must be used in a neutral 50 to 30 percent solution at a temperature near zero. Other methods described in the literature apparently do not work. The excess of hydrogen must be quickly sucked out of the brown precipitate, which it is best to wash with alcohol and ether. The product, crystalline under a microscope, can be analyzed only approximately. It approaches the formula CuO2H2O. In alkaline solution it appears to act catalytically in causing the decomposition of other peroxides, so that Na2O2 cannot be used to prepare it. On the addition of acids the H2O2 is regenerated. The dry substance decomposes much more slowly than the moist but is not very stable.

Moser, L.

1988-01-01

329

Evaluation of barium hydroxide treatment efficacy on a dolomitic marble.  

PubMed

The Arch of Peace, by Luigi Cagnola, is one of the most famous neoclassical monuments in Milan. It has been subjected to conservative intervention in 1998. In the present paper the efficacy of the consolidation by means of barium hydroxide has been evaluated. The stone material showed severe degradation phenomena as: erosion, pulverisation, exfoliation. The analytical data acquired through X-ray diffraction (XRD), infrared spectrophotometry (FTIR) and scanning electron microscopy (SEM-EDX), allowed to compare the conditions of stone before and after the treatment with barium hydroxide. The presence of barium has been put in evidence mainly on the surface as barium sulphate, whereas barium is only sporadically present within the thickness of the decayed material. The treatment was judged not satisfying and its inefficacy is, most probably, due to a not suitable cleaning procedure carried out before the consolidation. PMID:11836959

Toniolo, L; Colombo, C; Realini, M; Peraio, A; Positano, M

2001-01-01

330

Does peppermint oil relieve spasm during barium enema?  

PubMed

The effectiveness of topical peppermint oil added to barium sulphate suspension in relieving colonic muscle spasm during double contrast barium enema examination was assessed in a double blind study. 141 patients were randomized either to a control group (71 patients) examined with standard barium suspension or to the treatment group which received peppermint oil mixed with the barium preparation. No residual spasm was evident in a significant proportion of patients in the treated group (60%) compared with the control group (35%) (p < 0.001). The patients' acceptability of the procedure was good and there were no adverse effects on the overall quality of the examination. In conclusion, the addition of peppermint oil to the barium suspension seems to reduce the incidence of colonic spasm during the examination. The technique is simple, safe, cheap and it may lessen the need for intravenous administration of spasmolytic agents. PMID:7551780

Sparks, M J; O'Sullivan, P; Herrington, A A; Morcos, S K

1995-08-01

331

Iron overdose  

MedlinePLUS

Iron is an ingredient in many mineral and vitamin supplements. Iron supplements are also sold by themselves. Types include: Ferrous sulfate (Feosol, Slow Fe) Ferrous gluconate (Fergon) Ferrous fumarate (Femiron, Feostat) Note: This list may not be all-inclusive.

332

Eat Iron?!!  

NSDL National Science Digital Library

To gain an understanding of mixtures and the concept of separation of mixtures, students use strong magnets to find the element of iron in iron-fortified breakfast cereal flakes. Through this activity, they see how the iron component of this heterogeneous mixture (cereal) retains its properties and can thus be separated by physical means.

NSF GK-12 and Research Experience for Teachers (RET) Programs,

333

Effects on aqueous barium titanate tape properties of passivation of barium ion leaching by using dispersants  

Microsoft Academic Search

To passivate a barium titanate (BaTiO3) ceramic powder surface from Ba2+ ion leaching in water, passivation agent layer (PAL) was formed by drying the slurry after adding a commercial polymeric dispersant. By following the several characteristic steps of actual MLCC production process, slip and green properties were compared for two different polymer-adding modes; one is the PAL and the other

Dang-Hyok Yoon; Burtrand I. Lee

2004-01-01

334

The preparation of a novel polymer film based on salicylaldoxime and its influence on aqueous copper electrochemistry  

SciTech Connect

The metal complexing ligand salicylaldoxime was electropolymerized onto platinum electrodes and the resulting film characterized by reflectance FT-IR spectroscopy. The modified electrode response to aqueous iron, copper, cobalt and lead ions was investigated with the iron(III) and copper (II) ions showing significantly altered electrochemistry. The response of the modified electrode towards aqueous copper ion was found to be directly proportional to copper concentration with little interference from lead ions. The retention of copper ions, film stability and the nature of the film action are discussed along with its potential use in sensor construction.

Davis, J.; Vaughan, D.H.; Cardosi, M.F. [Univ. of Paisley, Scotland (United Kingdom)

1994-07-01

335

Designed microstructures in textured barium hexaferrite  

NASA Astrophysics Data System (ADS)

It is a fundamental principle of materials science that the microstructure of a material defines its properties and ultimately its performance for a given application. A prime example of this can be found in the large conch shell Strombus gigas, which has an intricate microstructure extending across five distinct length scales. This microstructure gives extraordinary damage tolerance to the shell. The structure of Strombus gigas cannot be replicated in a modern engineering ceramic with any existing processing technique, so new processing techniques must be developed to apply this structure to a model material. Barium hexaferrite was chosen as a model material to create microstructures reminiscent of Strombus gigas and evaluate its structure-property relations. This work describes novel processing methods to produce textured barium hexaferrite with no coupling between the sample geometry and the texture direction. This technique, combining magnetic field-assisted gelcasting with templated grain growth, also allows multilayer samples to be fabricated with different texture directions in adjacent layers. The effects of adding either B2O3 or excess BaCO 3 on the densification and grain growth of barium hexaferrite was studied. The texture produced using this technique was assessed using orientation imaging microscopy (OIM) at Oak Ridge National Laboratory. These measurements showed peak textures as high as 60 MRD and sharp interfaces between layers cast with different texture directions. The effect of oxygen on the quality of gelcasting is also discussed, and it is shown that with proper mold design, it is possible to gelcast multiple layers with differing texture directions without delamination. Monolithic and multilayer samples were produced and tested in four point bending to measure the strength and work of fracture. Modulus measurements, made with the ultrasonic pulse-echo technique, show clear signs of microcracking in both the isotropic and textured samples. Both the strength and work of fracture were shown to be affected by the texture direction. The multilayer samples did not show significant improvements in either strength or work of fracture, but they did show much less variability than the monolithic samples.

Hovis, David Brian

336

Cyanobacterial metallochaperone inhibits deleterious side reactions of copper.  

PubMed

Copper metallochaperones supply copper to cupro-proteins through copper-mediated protein-protein-interactions and it has been hypothesized that metallochaperones thereby inhibit copper from causing damage en route. Evidence is presented in support of this latter role for cyanobacterial metallochaperone, Atx1. In cyanobacteria Atx1 contributes towards the supply of copper to plastocyanin inside thylakoids but it is shown here that in copper-replete medium, copper can reach plastocyanin without Atx1. Unlike metallochaperone-independent copper-supply to superoxide dismutase in eukaryotes, glutathione is not essential for Atx1-independent supply to plastocyanin: Double mutants missing atx1 and gshB (encoding glutathione synthetase) accumulate the same number of atoms of copper per cell in the plastocyanin pool as wild type. Critically, ?atx1?gshB are hypersensitive to elevated copper relative to wild type cells and also relative to ?gshB single mutants with evidence that hypersensitivity arises due to the mislocation of copper to sites for other metals including iron and zinc. The zinc site on the amino-terminal domain (ZiaA(N)) of the P(1)-type zinc-transporting ATPase is especially similar to the copper site of the Atx1 target PacS(N), and ZiaA(N) will bind Cu(I) more tightly than zinc. An NMR model of a substituted-ZiaA(N)-Cu(I)-Atx1 heterodimer has been generated making it possible to visualize a juxtaposition of residues surrounding the ZiaA(N) zinc site, including Asp(18), which normally repulse Atx1. Equivalent repulsion between bacterial copper metallochaperones and the amino-terminal regions of P(1)-type ATPases for metals other than Cu(I) is conserved, again consistent with a role for copper metallochaperones to withhold copper from binding sites for other metals. PMID:22198771

Tottey, Steve; Patterson, Carl J; Banci, Lucia; Bertini, Ivano; Felli, Isabella C; Pavelkova, Anna; Dainty, Samantha J; Pernil, Rafael; Waldron, Kevin J; Foster, Andrew W; Robinson, Nigel J

2012-01-01

337

Cyanobacterial metallochaperone inhibits deleterious side reactions of copper  

PubMed Central

Copper metallochaperones supply copper to cupro-proteins through copper-mediated protein-protein-interactions and it has been hypothesized that metallochaperones thereby inhibit copper from causing damage en route. Evidence is presented in support of this latter role for cyanobacterial metallochaperone, Atx1. In cyanobacteria Atx1 contributes towards the supply of copper to plastocyanin inside thylakoids but it is shown here that in copper-replete medium, copper can reach plastocyanin without Atx1. Unlike metallochaperone-independent copper-supply to superoxide dismutase in eukaryotes, glutathione is not essential for Atx1-independent supply to plastocyanin: Double mutants missing atx1 and gshB (encoding glutathione synthetase) accumulate the same number of atoms of copper per cell in the plastocyanin pool as wild type. Critically, ?atx1?gshB are hypersensitive to elevated copper relative to wild type cells and also relative to ?gshB single mutants with evidence that hypersensitivity arises due to the mislocation of copper to sites for other metals including iron and zinc. The zinc site on the amino-terminal domain (ZiaAN) of the P1-type zinc-transporting ATPase is especially similar to the copper site of the Atx1 target PacSN, and ZiaAN will bind Cu(I) more tightly than zinc. An NMR model of a substituted-ZiaAN-Cu(I)-Atx1 heterodimer has been generated making it possible to visualize a juxtaposition of residues surrounding the ZiaAN zinc site, including Asp18, which normally repulse Atx1. Equivalent repulsion between bacterial copper metallochaperones and the amino-terminal regions of P1-type ATPases for metals other than Cu(I) is conserved, again consistent with a role for copper metallochaperones to withhold copper from binding sites for other metals. PMID:22198771

Tottey, Steve; Patterson, Carl J.; Banci, Lucia; Bertini, Ivano; Felli, Isabella C.; Pavelkova, Anna; Dainty, Samantha J.; Pernil, Rafael; Waldron, Kevin J.; Foster, Andrew W.; Robinson, Nigel J.

2012-01-01

338

Migration and redistribution of oxygen vacancy in barium titanate ceramics  

NASA Astrophysics Data System (ADS)

Degradation of barium titanate based multilayer capacitor mainly results from migration and redistribution of oxygen vacancy. For barium titanate ceramics, the authors observe an internal friction relaxation peak around 70°C due to oxygen vacancy, and its relaxation strength differs greatly for specimen aged at 85°C for 120h and at 150°C for 5h. Two possible explanations are proposed, one based on symmetry-conforming short-range order while the other on the interaction between oxygen vacancy and domain wall during aging process. In any case, relaxation thermodynamics is a powerful tool to investigate the migration and redistribution of oxygen vacancy in barium titanate ceramics.

Chen, L.; Xiong, X. M.; Meng, H.; Lv, P.; Zhang, J. X.

2006-08-01

339

Migration and redistribution of oxygen vacancy in barium titanate ceramics  

SciTech Connect

Degradation of barium titanate based multilayer capacitor mainly results from migration and redistribution of oxygen vacancy. For barium titanate ceramics, the authors observe an internal friction relaxation peak around 70 deg. C due to oxygen vacancy, and its relaxation strength differs greatly for specimen aged at 85 deg. C for 120 h and at 150 deg. C for 5 h. Two possible explanations are proposed, one based on symmetry-conforming short-range order while the other on the interaction between oxygen vacancy and domain wall during aging process. In any case, relaxation thermodynamics is a powerful tool to investigate the migration and redistribution of oxygen vacancy in barium titanate ceramics.

Chen, L.; Xiong, X. M.; Meng, H.; Lv, P.; Zhang, J. X. [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

2006-08-14

340

A high-altitude barium radial injection experiment  

NASA Technical Reports Server (NTRS)

A rocket launched from Poker Flat, Alaska, carried a new type of high-explosive barium shaped charge to 571 km, where detonation injected a thin disk of barium vapor with high velocity nearly perpendicular to the magnetic field. The TV images of the injection are spectacular, revealing three major regimes of expanding plasma which showed early instabilities in the neutral gas. The most unusual effect of the injection is a peculiar rayed barium-ion structure lying in the injection plane and centered on a 5 km 'black hole' surrounding the injection point. Preliminary electrostatic computer simulations show a similar rayed development.

Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hallinan, T. J.; Deehr, C. S.; Romick, G. J.; Olson, J. V.; Roederer, J. G.; Sydora, R.

1980-01-01

341

Thermodynamics of Iron Oxidation in Metallurgical Slags  

NASA Astrophysics Data System (ADS)

The state of oxidation of a pyrometallurgical process, given by the partial pressure of oxygen and the temperature, is one of the important properties monitored and controlled in the smelting and refining of iron and the nonferrous metals. This article reviews the thermodynamic background for this quantity and examines some empirical methods for its estimation and use. The emphasis is on copper smelting, but the same principles apply to iron, nickel, lead, and zinc processes.

Matousek, Jan

2012-11-01

342

Magnetic and structural properties of M-type barium hexaferrite prepared by co-precipitation  

NASA Astrophysics Data System (ADS)

Stoichiometric and single-phase barium hexaferrite (BaM) has been synthesized by co-precipitation and an additional solid state preparative method using high-purity nitrates, oxides and carbonates of iron (III), barium (II) and ammonium hydroxide. The isochronally and isothermally measured permeability and magnetic loss tangents over 1 MHz-1 GHz in frequency remained moderately constant until a sintering temperature of 1300 °C where relative permeability of 1.3 and loss tangent of 0.06 at 1 GHz, indicate high-frequency magnetic characteristics for BaM. TGA/DTA studies showed the hexaferrite formation temperature was found to be 1050 °C. The apparent densities before and after each firing cycle showed a monotonic increase. X-ray diffraction studies established the presence of a single phase with the theoretical space group P63/mmc, and computed cell parameters of a= b=5.895 Å and c=23.199 Å. The samples exhibited a Curie point ( Tc) of 452 °C and displayed ferromagnetic resonance characteristics centred on a frequency of 500 MHz.

Shepherd, Philip; Mallick, Kajal K.; Green, Roger J.

2007-04-01

343

Phased surgical treatment of barium enema-induced rectal injury and retention of barium in the pelvic floor space  

PubMed Central

Iatrogenic injuries caused by barium enema are rarely reported. Following a phased surgical protocol for up to one year, we have successfully treated a patient with rectal injury and severe infection of the pelvic floor space complicated with retention of large amounts of barium and vaginal fistula. In this article, the phased surgery planning for the treatment of rectal injury complicated with vaginal fistula is discussed in terms of the pros and cons, and the observed effect and evolution of barium retained in the pelvic floor space are described. PMID:25405155

Yang, Xuefei; Xia, Ligang; Huang, Jun; Wang, Jianping

2014-01-01

344

Synthesis and Properties of Yttrium BARIUM(2)COPPER(3)OXYGEN(7) and YTTRIUM(2)BARIUM(4)COPPER(8)OXYGEN(16) Thin Films  

NASA Astrophysics Data System (ADS)

This work presents some transport and structural properties of YBa_2 Cu_3 O_7 and Y_2Ba_4 Cu_8 O_{16} thin films fabricated in a desired orientation by reactive magnetron sputtering and e-beam evaporation. A reactive magnetron sputtering technique was developed for these oxide thin films. Three metal targets were co-sputtered onto SrTiO_3 {100} substrates with oxygen sprayed from nearby. With post-deposition annealing, films of excellent quality with thicknesses ranging from 500 A to 5 ?m were successfully made. It was found that the orientation of the films can be controlled by having the proper composition, thickness and post-deposition heat treatment. Normal state properties of YBa _2 Cu_3 O_7 measured by resistivity and Hall coefficient show anisotropic behavior different from those of, conventional metals; it has a high resistivity rho_{ab} (100 K) ~100 muOmega cm linear with temperature and a low carrier density n_{ab} (100K) ~3 times 10^{21} cm^{-1} of holes. Fluctuation conductivity measurements above T_{c} shows Lawrence-Doniach type 2D to 3D crossover behavior with xi_{c} (0) ~2A. Upper critical field, H _{c2}, measurements show very short coherence lengths of xi _{ab}(0) ~16 A and xi_{c} (0) ~2 A. These short coherence lengths together with the high transition temperature cause unusually large flux motion. High critical current densities, J_{c}, in excess of 1 times 10^7 A/cm ^2 at 4.2 K and 1 times 10 ^6 A/cm^2 at 77 K were measured in the c-axis oriented films. An ordered defect structure Y _2 Ba_4 Cu_8 O_{16} has discovered and its properties were studied. It has a T_{c} of 81 K and is characterized by its lower normal state resistivity and lower Hall coefficient compared to YBa_2 Cu_3 O_7. Its unique double Cu-O chain layers show that the chains play an important role in normal state properties. Its linear resistivity versus temperature, which extrapolates to zero at 55 K, indicates a scattering mechanism similar to those of pure metals. Faulted structure generated from random layering of YBa_2 Cu_3 O_7 and Y_2 Ba_4 Cu _8 O_{16} raises T _{c} which can sometimes get as high as 95 K.

Char, Kookrin

345

Electrical and Magnetic Properties of the Percolative Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA) - YTTRIUM(2) Barium Copper OXYGEN(5) Systems  

NASA Astrophysics Data System (ADS)

The electrical and magnetic behaviour of the mixed two phase, percolative system, YBCO(123)-YBCO(211) has been investigated. The normal-state resistivity of this system is best represented by a variable range hopping (VRH) model in which the electronic states of the system are localized. From this model the localization length, alpha^{-1} and the activation energies involved in the hopping process have been determined. The form of the superconducting resistive transition is shown to depend strongly on the intergranular weak-link structure. The resistivity tails have been interpreted in terms of the phase slip and thermally activated flux creep models with the magnetic field dependence of the activation energies found to follow an inverse power-law relationship. A detailed investigation of the ac magnetic susceptibility of this system has shown that the flux pinning energies were found to decrease rapidly as the Y_ {211} concentration increased. These measurements support the view that the observed pinning is associated with the intergranular weak-link system rather than with the intrinsic crystalline material. Changes in the H-T phase diagram have been established as a function of composition and it is found that the irreversibility line (IL) is consistent with H^{rm q}~ (1-t), while the IL moves to lower temperatures and magnetic fields as the intergranular pinning strengths are decreased. DC field dependent ac susceptibility results have been adequately described by a critical state model in which the critical current density is given by alpha(T)/(H_{rm o} + H_{{dc }})^{rm n}. The functional relationship of the material dependent parameter alpha(T) has been determined. The hysteresis behaviour of chi_{ {ac}} H_ {{dc}} in a cycled dc magnetic field have been measured and the average lower critical field, H_{{clg }} for the superconducting grains has been established and its temperature dependence determined. The internal relationship between the susceptibility components chi^{'} _{{ac}} and chi^{''} _{{ac}} have been investigated theoretically and experimentally. A significant difference exists between the observed and predicted results which has been discussed.

Sedghi Gamchi, Hassan

1995-01-01

346

Superplastic Deformation of High Transition Temperature Superconductors: Yttrium BARIUM(2), COPPER(3) OXYGEN(7 - and Yttrium BARIUM(2) COPPER(3) OXYGEN(7-X) Silver.  

NASA Astrophysics Data System (ADS)

Superplasticity in the rm YBa_2Cu _3O_{7-x} ceramic superconductor and composites containing 2.5-25% silver was studied. Large deformation over 100% was observed in these materials in the temperature range of 775-875^circ C at strain rates of 1times10^ {-5} to 1times10^ {-3}/sec and grain sizes of 0.5-1.4 mum. The nature of the deformation behavior was investigated in terms of three deformation parameters: the stress exponent (n); grain size exponent (p); and activation energy (Q). For both the undoped and Ag-doped materials n = 2, p cong 2.5, and Q cong 750kJ/mol. By constructing the deformation map, the deformation mechanism was identified as grain boundary sliding accommodated by grain boundary diffusion, controlled by either the interface reaction rate at the grain boundary, or grain boundary sliding rate. The conclusion was consistent with microstructural observations made under the light optical microscope, scanning electron microscope, and transmission electron microscope. These observations show a lack of significant dislocation activity and intergranular second phase, insignificant texture development, and the maintenance of equiaxed grain shape. The superplastic deformation behavior of the composites followed the soft inclusion model of Chen. The effect of superplastic deformation on superconductivity was also examined. For rm YBa_2Cu _3O_{7-x}, T_{c } remained unchanged with deformation. For the composite, T_{rm c} generally decreased after deformation. It was found that the oxygenation rate was decreased with deformation in the presence of silver.

Yun, Jondo

347

Normal State Transport in Superconducting Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA) and Semiconducting Praseodymium BARIUM(2) COPPER(3) OXYGEN(7-DELTA)  

NASA Astrophysics Data System (ADS)

The discovery, in 1986, of materials with superconducting transition temperatures well above 77 K has generated a renewed interest in potential applications for superconductors. Unfortunately, the widespread use of high temperature superconductors (HTS) has not been realized due to their poor performance in terms of electrical and physical properties. Although the mechanism of high temperature superconductivity remains a mystery, it is hoped that an understanding of the HTS will result in the ability to engineer better quality materials. The normal state of the HTS exhibits several features which are considered unusual. Among these features are a linear temperature dependence of the resistivity and a temperature dependent Hall effect. It is believed that knowledge of the normal state transport properties of the HTS is crucial to understanding superconductivity in these materials. In an effort to better understand the normal state of the these materials, the transport properties of single crystal samples of two members of the superconducting RBa_2Cu_3O _{7-delta} ("123") family were studied (R = yttrium and many of the rare earth elements). Resistivity, Hall effect, and magnetoresistance measurements were performed on a detwinned single crystal sample of YBa_2Cu_3 _{7-delta} (Y 123). Measurements were repeated after various oxygen anneals to study the effects of oxygen inhomogeneities on the sample's transport properties. These results indicate that oxygen inhomogeneities strongly influence the transport properties of this system. A model is presented which takes into account oxygen defects in calculating the resistivity and Hall coefficient. Of the rare earth elements that will form the 123 structure, only PrBa_2Cu _3O_{7-delta} (Pr 123) does not superconduct. Pr 123 exhibits a non-metallic temperature dependent resistivity as opposed to the metallic resistivity exhibited by the superconducting 123 family members. Magnetotransport and magnetization measurements were performed on a single crystal sample of Pr 123. These measurements show a correlation between the magnetic state of the Pr ion and transport in the Cu -O planes. Based on these results, an explanation of the "anomalous" behavior of Pr 123 is given.

Browning, Valerie Michelle

1995-01-01

348

Enhanced Kosterlitz-Thouless Transitions in Yttrium BARIUM(2) COPPER(3) OXYGEN(7-X)/PRASEODYMIUM BARIUM(2) COPPER(3) OXYGEN(7-X) Superlattices  

NASA Astrophysics Data System (ADS)

The superconducting properties of YBa _2Cu_3O_ {7-x}/PrBa_2Cu _3O_{7-x} superlattices with ultrathin YBa_2 Cu_3O_{7 -x} layers were studied. The superlattices were multilayered films grown epitaxially on (100) SrTiO_3 and LaAlO_3 substrates by pulsed-laser deposition. They were characterized by several methods and found to have good structural and electrical characteristics. Strongly enhanced Kosterlitz-Thouless transitions were observed in the multilayers composed of two and four unit cells of YBa_2Cu_3 O_{7-x}, separated by insulating PrBa_2Cu_3 O_{7-x}. The parameter tau_{KT} = (T_{co} - T_{KT})/ T_{co} was up to an order of magnitude larger than in single crystals or in thicker films of YBa_2Cu _3O_{7-x}, showing that two-dimensional behavior is more closely approached in the multilayers. Here T_{co} is the mean-field transition temperature and T_{KT} is the Kosterlitz-Thouless transition temperature. Our results confirm that the enhancement of two -dimensionality is accompanied by a lowering of T _{co} in the ultrathin layers of YBa_2Cu_3 O_{7-x}. We interpret this as direct evidence that interlayer coupling is essential for the higher transition temperature observed in the bulk.

Vadlamannati, Sharma S.

1991-02-01

349

Mechanisms of Copper Ion Mediated Huntington's Disease Progression  

PubMed Central

Huntington's disease (HD) is caused by a dominant polyglutamine expansion within the N-terminus of huntingtin protein and results in oxidative stress, energetic insufficiency and striatal degeneration. Copper and iron are increased in the striata of HD patients, but the role of these metals in HD pathogenesis is unknown. We found, using inductively-coupled-plasma mass spectroscopy, that elevations of copper and iron found in human HD brain are reiterated in the brains of affected HD transgenic mice. Increased brain copper correlated with decreased levels of the copper export protein, amyloid precursor protein. We hypothesized that increased amounts of copper bound to low affinity sites could contribute to pro-oxidant activities and neurodegeneration. We focused on two proteins: huntingtin, because of its centrality to HD, and lactate dehydrogenase (LDH), because of its documented sensitivity to copper, necessity for normoxic brain energy metabolism and evidence for altered lactate metabolism in HD brain. The first 171 amino acids of wild-type huntingtin, and its glutamine expanded mutant form, interacted with copper, but not iron. N171 reduced Cu2+ in vitro in a 1?1 copper?protein stoichiometry indicating that this fragment is very redox active. Further, copper promoted and metal chelation inhibited aggregation of cell-free huntingtin. We found decreased LDH activity, but not protein, and increased lactate levels in HD transgenic mouse brain. The LDH inhibitor oxamate resulted in neurodegeneration when delivered intra-striatially to healthy mice, indicating that LDH inhibition is relevant to neurodegeneration in HD. Our findings support a role of pro-oxidant copper-protein interactions in HD progression and offer a novel target for pharmacotherapeutics. PMID:17396163

Fox, Jonathan H.; Kama, Jibrin A.; Lieberman, Gregory; Chopra, Raman; Dorsey, Kate; Chopra, Vanita; Volitakis, Irene; Cherny, Robert A.; Bush, Ashley I.; Hersch, Steven

2007-01-01

350

COPPER CORROSION RESEARCH UPDATE  

EPA Science Inventory

Copper release and corrosion related issues continue to be important to many water systems. The objective of this presentation is to discuss the current state of copper research at the USEPA. Specifically, the role of aging on copper release, use of phosphates for copper corrosio...

351

Study of the photovoltaic effect in thin film barium titanate  

NASA Technical Reports Server (NTRS)

The feasibility of making non-volatile digital memory devices of barium titanate, BaTiO3, that are integrated onto a silicon substrate with the required ferroelectric film produced by processing, compatible with silicon technology was examined.

Grannemann, W. W.; Dharmadhikari, V. S.

1983-01-01

352

Calculated emission rates for barium releases in space  

NASA Technical Reports Server (NTRS)

The optical emissions from barium releases in space are caused by resonance and fluorescent scattering of sunlight. Emission rates for the dominant ion and neutral lines are calculated assuming the release to be optically thin and the barium to be in radiative equilibrium with the solar radiation. The solar spectrum has deep Fraunhofer absorption lines at the primary barium ion resonances. A velocity component toward or away from the sun will Doppler shift the emission lines relative to the absorption lines and the emission rates will increase many-fold over the rest value. The Doppler brightening is important in shaped charge or satellite releases where the barium is injected at high velocities. Emission rates as a function of velocity are calculated for the 4554, 4934, 5854, 6142 and 6497 A ion emission lines and the dominant neutral line at 5535 A. Results are presented for injection parallel to the ambient magnetic field, B, and for injection at an angle to B.

Stenbaek-Nielsen, H. C.

1989-01-01

353

Searching for specific responses to copper exposure: an in vitro copper challenge in peripheral mononuclear cells.  

PubMed

Acute and chronic cellular responses to changes in copper availability are not clear when these changes are mild to moderate, as what often occur in human daily life. The aims of the study were to develop an in vitro copper challenge in peripheral mononuclear cells (PMNCs) obtained from healthy individuals with different preconditioning copper treatments, and measure copper and iron content, and MT2A and TfR mRNA abundance after the copper challenge. (1) Screening using clinical and biochemical indicators defined healthy participants, who received 8 mg Cu/day (copper sulfate) or placebo for 2 months. (2) Mononuclear cells were obtained on days 0, 2 (acute changes), and 60 (chronic changes). (3) Cells were challenged with a 1, 5, and 20 ?M Cu-histidine for 20 h, at T0, T2, and T60. Cells from both supplemented and placebo individuals showed a clear trend to increase copper content when there was more copper in the media. Increases were greater in the supplemented group, larger with 20 ?M Cu (p?iron content were significant by treatment and time (two-way ANOVA); mRNA relative abundance of MT2A changed significantly and paralleled those of copper concentration, but TfR transcripts did not change. An in vitro challenge of PMNC showed specific changes of cellular copper and MT2A, while changes of iron content and TfR mRNA abundance were not consistent. PMNCs appear as good candidates to assess changes of cellular copper availability. That results differed after acute (T2) and chronic (T60) supplementation suggests that acute and chronic changes are handled differently by these cells. PMID:20737243

Arredondo, Miguel; Espinoza, Alejandra; Pizarro, Fernando; Araya, Magdalena

2011-09-01

354

[Copper and copper alloys. Technology updates].  

PubMed

The correlations between copper and copper alloys and human health have been the subject of some recent and extensive scientific researches. The voluntary risks evaluation, which anticipated the EU REACH Directive application, has shown that copper is a "safe" product for human health and for environment. In addition, it could be of great help thanks to its antibacterial properties. Copper tube can contribute in a relevant way to the prevention of water systems pollution by Legionella. Also the spreading of nosocomial infections is significantly contrasted by the use of copper and copper alloys for the production of articles intended for being frequently touched by people. The Environmental Protection Agency of the United States has in fact "registered" as antibacterial over 350 of copper alloys. PMID:23213799

Loconsolo, V; Crespi, M

2012-01-01

355

Copper Data Center Database  

NSDL National Science Digital Library

The Copper Data Center Database is provided free of charge by the Copper Development Association "to increase knowledge and awareness of copper, related technologies, and the role of copper in the environment." The database is an online bibliographic search engine of literature on copper, copper alloys and copper technology dating back to 1965 and is described as covering copper technology from smelting and hydrometallurgy through the performance of copper and copper alloys in their end-use applications and service environments. Users can search by standard methods including using keywords and titles or an impressive advanced search feature is also available. Although full text listings are not available, anyone interested in related subjects will appreciate this well designed and unique tool.

Association, Copper D.

356

Solar eclipse sign of intussusception on barium enema.  

PubMed

The colographic appearance of intussusception is variously described as a claw sign, pincer defect, shouldering effect, and coiled-spring pattern. This report adds a new radiographic sign to the list. An end-on view of an intussusception on barium enema shows a ring of contrast resembling a solar eclipse. Familiarity with this bizarre appearance is desirable, lest it may be mistaken for spillage of barium due to a colonic perforation. PMID:11793074

Raveenthiran, V

2002-01-01

357

Thermal expansion of nitrates of lead, barium and strontium  

Microsoft Academic Search

The expansion coefficients of barium, strontium and lead nitrates have been studied above room temperatures. Lead nitrate\\u000a decomposes rapidly beyond 200° C. while crystals of barium nitrate crack above 270° C. Strontium nitrate exhibited no such\\u000a phenomena till 550° C.\\u000a \\u000a These crystals are isomorphous. The expansion coefficients of lead and strontium nitrates are nearly equal; they also possess\\u000a the same

R. Srinivasan

1955-01-01

358

'Skidding' of the CRRES G-9 barium release  

NASA Technical Reports Server (NTRS)

A simulation study and experimental data of the CRRES G-9 ionospheric barium release are presented. The simulation study is based on a 2D electrostatic code that incorporates time-dependent coupling to the background plasma. It is shown that the densest portion of the barium ion cloud 'skids' about 15 km within the first three seconds following the release, consistent with the optical data analyses.

Huba, J. D.; Mitchell, H. G.; Fedder, J. A.; Bernhardt, P. A.

1992-01-01

359

Low density barium and bentonite mixture versus high density barium: A comparative study to optimize negative gastrointestinal contrast agents for MRI  

Microsoft Academic Search

The purpose of this study was to compare the patient tolerance and efficacy, as magnetic resonance imaging negative oral contrast agents, of a mixture of clay compound bentonite and low density barium sulfate suspension with that of higher density barium sulfate. Twenty patients were randomized into two groups: 10 patients receiving a mixture of low concentration 60% wv barium sulfate

Mark R. Paley; Ana I. Nicolas; Patricia J. Mergo; Gladys M. Torres; Sharon S. Burton; Pablo R. Ros

1997-01-01

360

Cape York: The extraordinary mineralogy of an ordinary iron meteorite and its implication for the genesis of III AB irons  

Microsoft Academic Search

A study of accessory minerals in the Cape York iron meteorite was carried out with the electron microprobe. Phases analyzed include chromite, sphalerite, two closely related potassium bearing sulfides, silica, and native copper. Four phosphate minerals were found: one chemically similar to buchwaldite, but rather rich in iron, one corresponding to terrestrial maricite, and two more, which are new minerals

A. Kracher; G. Kurat; V. F. Buchwald

1977-01-01

361

Structural and optical absorption studies of barium substituted strontium ferrite powder  

NASA Astrophysics Data System (ADS)

Attempt has been made to synthesize BaxSr1-xFeO3-? (x = 0-1.0) ferrite powder by decomposition of sol-gel derived oxalate at 800-1000 °C for 5-10 h to study the effect of barium insertion with regard to phase(s), stability, optical behavior, oxidation states of iron, and oxygen deficiency. It is shown that these ferrites possess a perovskite-type cubic phase (a = 3.877-4.020Å, Z = 1, space group Pm3m) for 0.1 ? x ? 0.94, a mixture of 82% rhombohedral (aR = 5.666Å and ?R = 59.761°, Z = 2, space group R3c) and 18% hexagonal phases for x = 0.96 and a pure hexagonal (a = 5.689Å, c = 13.944Å, Z = 6, space group P63/mmc) phase for x = 1. Barium substitution in SrFeO3-? system leads to lattice expansion, weakening of the metal-oxygen bond, reduction of tetravalent iron ions (as evident from Mossbauer analysis), and decrease of oxygen content. The optical absorption peaks observed in the range 3.17-4.11 eV are attributed to charge transfer transitions from O2- (2p) to Fe (3d) band. The values of optical energy band gap of BaxSr1-xFeO3-? are found to be ˜5.48 and ˜4.04 for x = 0.1 and 1.0, respectively. A stable perovskite-type cubic phase in BaxSr1-xFeO3-? system with significant anion deficiency (? = 0.26-0.32) may possibly act as an oxygen permeable membrane.

Jaiswal, Shivendra Kumar; Kumar, Jitendra

2012-08-01

362

Increased brain iron coincides with early plaque formation in a mouse model of Alzheimer's disease  

Microsoft Academic Search

Elevated brain iron content, which has been observed in late-stage human Alzheimer's disease, is a potential target for early diagnosis. However, the time course for iron accumulation is currently unclear. Using the PSAPP mouse model of amyloid plaque formation, we conducted a time course study of metal ion content and distribution [iron (Fe), copper (Cu), and zinc (Zn)] in the

A. C. Leskovjan; L. Miller; A. Kretlow; A. Lanzirotti; R. Barrea; S. Vogt

2010-01-01

363

Increased brain iron coincides with early plaque formation in a mouse model of Alzheimer's disease  

Microsoft Academic Search

Elevated brain iron content, which has been observed in late-stage human Alzheimer's disease, is a potential target for early diagnosis. However, the time course for iron accumulation is currently unclear. Using the PSAPP mouse model of amyloid plaque formation, we conducted a time course study of metal ion content and distribution [iron (Fe), copper (Cu), and zinc (Zn)] in the

Andreana C. Leskovjan; Ariane Kretlow; Antonio Lanzirotti; Raul Barrea; Stefan Vogt; Lisa M. Miller

2011-01-01

364

Effect of anions on selective solubilization of zinc and copper in bacterial leaching of sulfide ores.  

PubMed

Bacterial leaching of sulfide ores using Thiobacillus ferrooxidans, Thiobacillus thiooxidans, or a combination of the two was studied at various concentrations of specific anions. Selective zinc and copper solubilization was obtained by inhibiting iron oxidation without affecting sulfur/sulfide oxidation. Phosphate reduced iron solubilization from a pyrite (FeS(2))-sphalerite (ZnS) mixture without significantly affecting zinc solubilization. Copper leaching from a chalcopyrite (CuFeS(2))-sphalerite mixture was stimulated by phosphate, whereas chloride accelerated zinc extraction. In a complex sulfide ore containing pyrite, chalcopyrite, and sphalerite, both phosphate and chloride reduced iron solubilization and increased copper extraction, whereas only chloride stimulated zinc extraction. Maximum leaching obtained was 100% zinc and 50% copper. Time-course studies of copper and zinc solubilization suggest the possibility of selective metal recovery following treatment with specific anions. PMID:10861398

Harahuc, L; Lizama, H M; Suzuki, I

2000-07-20

365

Electroplating of iron from alkaline gluconate baths  

Microsoft Academic Search

Electroplating of iron onto copper substrates from non-polluting baths containing ferrous sulfate and sodium gluconate has been investigated under different bath composition, pH, temperature and current density conditions. A detailed study has been made on the influence of these parameters on potentiodynamic polarization curves, cathodic current efficiency and throwing power of the baths. The optimum plating bath has been found

E. A Abd El Meguid; S. S Abd El Rehim; E. M Moustafa

2003-01-01

366

The Viscous and Conductivity Behavior of Melts Containing Iron Oxide in the FeOt-SiO2-CaO-Cu2O System for Copper Smelting Slags  

NASA Astrophysics Data System (ADS)

The control of the slag properties has become very essential in improving (1) the separation between the slag and the matte and (2) the operation of electric smelting furnaces in the copper pyrometallurgical process. The viscosities and electrical conductivities of FeOt-SiO2-CaO-Cu2O copper smelting slags were measured using the rotational spindle method and the standard direct-current (DC) four-probe method, respectively, in this article. The influences of the common constituents of CaO, Fe3O4, Cu2O in the basic slag system of FeO-SiO2 on the viscosity and conductivity have been investigated. The results showed that the effects of these three compositions on viscosity and conductivity were much more complicated due to the transition of the basic slag compositions. The apparent activity energy of viscosity and the relationship between viscosity and electrical conductivity are also mentioned in the study.

Huaiwei, Zhang; Fei, Sun; Xiaoyan, Shi; Bo, Zhang; Xin, Hong

2012-10-01

367

Iron refractory iron deficiency anemia  

PubMed Central

Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach. PMID:23729726

De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U.; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

2013-01-01

368

Role of microbial iron reduction in the dissolution of iron hydroxysulfate minerals  

Microsoft Academic Search

Iron-hydroxysulfate minerals can be important hosts for metals such as lead, mercury, copper, zinc, silver, chromium, arsenic, and selenium and for radionuclides such as 226Ra. These mineral-bound contaminants are considered immobilized under oxic conditions. However, when anoxic conditions develop, the activities of sulfate- or iron-reducing bacteria could result in mineral dissolution, releasing these bound contaminants. Reduction of structural sulfate in

Elizabeth J. P. Jones; Tracie-Lynn Nadeau; Mary A. Voytek; Edward R. Landa

2006-01-01

369

Co-doped Barium Phosphate Glass  

NASA Astrophysics Data System (ADS)

Co-doping of a P2O5:BaO glass matrix with divalent tin and trivalent samarium ions has been realized by the melt-quenching technique with the purpose of investigating the material's luminescent properties. Photoluminescence excitation spectra obtained by monitoring Sm3+ 4G5/2 emission showed a broad excitation band around 290 nm (absent in a Sm3+-doped reference), typical of donor/acceptor energy transfer. Under such excitation, the material exhibits a reddish-white emission. Time-resolved spectra recorded under the 290-nm excitation (non-resonant with Sm3+ excitation peaks) exposed a broad blue-white band characteristic of twofold-coordinated Sn centers and orange-red emission bands of Sm3+ ions, which appeared well separated in time in accord with their emission decay dynamics. Consequently, the data indicate that light absorption occurs at Sn centers (donors) followed by energy transfer to samarium ions (acceptors) which results in populating the 4G5/2 emitting state in Sm3+. Energy transfer pathways likely resulting in the sensitization of Sm3+ photoluminescence are discussed. Results are put into context in terms of the potential of SnO and rare-earth co-doped barium phosphate glasses for use in white light-emitting devices.

Jiménez, J. A.

2014-09-01

370

Copper-phosphorus alloys offer advantages in brazing copper  

Microsoft Academic Search

Copper-phosphorus brazing alloys are used extensively for joining copper, especially refrigeration and air-conditioning copper tubing and electrical conductors. What is the effect of phosphorus when alloyed with copper? The following are some of the major effects: (1) It lowers the melt temperature of copper (a temperature depressant). (2) It increases the fluidity of the copper when in the liquid state.

1996-01-01

371

Copper ferrite nanoparticle-mediated N-arylation of heterocycles: a ligand-free reaction  

Microsoft Academic Search

The synergistic effects of iron and copper in copper ferrite nanoparticles for the N-arylation of heterocycles with aryl halides were demonstrated. The magnetic nature of the catalyst facilitates its removal from the reaction medium for further use. Negligible leaching of Cu and Fe in consecutive cycles makes the catalyst economical and environmentally benign for C–N cross-coupling reactions.

Niranjan Panda; Ashis Kumar Jena; Sasmita Mohapatra; Smruti Ranjan Rout

2011-01-01

372

High copper concentrations in squid livers in association with elevated levels of silver, cadmium, and zinc  

Microsoft Academic Search

Livers from 43 Loligo opalescens, 14 Ommastrephes bartrami, and 7 Symplectoteuthis oualaniensis were analyzed for their silver, cadmium, copper, zinc and iron contents. Copper concentrations of up to 15,000 µg\\/g dry weight were found in L. opalescens in conjunction with significant correlations between this element and Ag, Cd and Zn. The latter elements are known to affect Cu metabolism in

J. H. Martin; A. R. Flegal

1975-01-01

373

Copper and silver nanocrystals in lustre lead glazes: Development and optical properties  

Microsoft Academic Search

In the early 9th century AD ancient potters of Iraq discovered that after firing some copper oxides and silver salts with clay, iron oxides and some sulphur compounds applied on a ceramic glaze produced a beautiful layer with a wide range of colours, from reddish to yellowish or even greenish, and some with a characteristic metallic copper or purplish shine.

J. Roqué; J. Molera; P. Sciau; E. Pantos; M. Vendrell-Saz

2006-01-01

374

D-penicillamine treatment of copper-associated hepatitis in Labrador retrievers.  

PubMed

d-penicillamine is effectively used in the lifelong treatment of copper toxicosis in Bedlington terriers and Wilson's disease in humans. A complex form of copper-associated hepatitis has recently been characterized in the Labrador retriever. The aims of this study were to evaluate the effectiveness of d-penicillamine treatment for copper-associated hepatitis in this breed, to study the effects on hepatic copper, iron and zinc concentrations, and to evaluate parameters to predict optimal duration of treatment. Forty-three client owned Labrador retrievers that were diagnosed with increased hepatic copper were treated with d-penicillamine and underwent at least one follow-up examination including a liver biopsy for histopathological scoring of inflammatory lesions. Hepatic copper, iron and zinc concentrations were determined in the initial and follow-up biopsies by instrumental neutron activation analysis. The influence of initial hepatic copper concentration, sex, age, d-penicillamine formulation and the occurrence of side effects were investigated for their influence on hepatic copper concentration after a certain period of treatment by generalized mixed modelling. d-penicillamine proved to be effective in reducing hepatic copper concentration and associated inflammatory lesions. Parameters derived from the model can be used to estimate the necessary duration of d-penicillamine treatment for Labrador retrievers with increased hepatic copper concentration. Continuous, lifelong d-penicillamine treatment is not recommended in this breed, as there may be a risk for hepatic copper and zinc deficiency. PMID:23375251

Fieten, Hille; Dirksen, Karen; van den Ingh, Ted S G A M; Winter, Esther A; Watson, Adrian L; Leegwater, Peter A J; Rothuizen, Jan

2013-06-01

375

Creating unstable velocity-space distributions with barium injections  

SciTech Connect

Large Debye lengths relative to detector dimensions and the absence of confining walls makes space an attractive laboratory for studying fundamental theories of plasma instabilities. However, natural space plasmas are rarely found displaced from equilibrium enough to permit isolation and diagnosis of the controlling parameters and driving conditions. Furthermore, any plasma or field response to the departure from equilibrium can be masked by noise in the natural system. Active experiments provide a technique for addressing the chicken or egg dilemma. Early thermite barium releases were generally conducted at low altitudes from sounding rockets to trace electric fields passively or to study configuration-space instabilities. One can also study velocity-space instabilities with barium releases. Neutral barium vapor releases wherein a typical speed greatly exceeds the thermal speed can be used to produce barium ion velocity-space distributions that should be subject to a number of microinstabilities. We examine the ion velocity-space distributions resulting from barium injections from orbiting spacecraft and shaped-charges.

Pongratz, M.B.

1983-01-01

376

Acceleration of barium ions near 8000 km above an aurora  

NASA Technical Reports Server (NTRS)

A barium shaped charge, named Limerick, was released from a rocket launched from Poker Flat Research Range, Alaska, on March 30, 1982, at 1033 UT. The release took place in a small auroral breakup. The jet of ionized barium reached an altitude of 8100 km 14.5 min after release, indicating that there were no parallel electric fields below this altitude. At 8100 km the jet appeared to stop. Analysis shows that the barium at this altitude was effectively removed from the tip. It is concluded that the barium was actually accelerated upward, resulting in a large decrease in the line-of-sight density and hence the optical intensity. The parallel electric potential in the acceleration region must have been greater than 1 kV over an altitude interval of less than 200 km. The acceleration region, although presumably auroral in origin, did not seem to be related to individual auroral structures, but appeared to be a large-scale horizontal structure. The perpendicular electric field below, as deduced from the drift of the barium, was temporally and spatially very uniform and showed no variation related to individual auroral structures passing through.

Stenbaek-Nielsen, H. C.; Hallinan, T. J.; Wescott, E. M.; Foeppl, H.

1984-01-01

377

The link between reduced porphyry copper deposits and oxidized magmas  

NASA Astrophysics Data System (ADS)

Porphyry copper deposits account for more than 80% of the world's total Cu resources. However, the formation mechanism and controlling factors of porphyry copper deposits remain obscure. Previous studies have revealed that porphyry copper deposits are usually associated with oxidized, calc-alkalic, adakitic shallow intrusive rocks. Here we show that hematite-magnetite intergrowths are commonly found in porphyry copper deposits, suggesting high and fluctuating oxygen fugacity (fO2). Oxidation promotes the destruction of sulfides in the magma source, and thereby increases initial chalcophile element concentrations. Sulfide remains undersaturated during the evolution of oxidized sulfur-enriched magmas where sulfate is the dominant sulfur species, leading to high chalcophile element concentrations in evolved magmas. The final porphyry copper mineralization is controlled by sulfate reduction, which starts with magnetite crystallization, accompanied by decreasing pH and correspondingly increasing fO2. Hematite forms once sulfate reduction lowers the pH sufficiently and the fO2 reaches the hematite-magnetite oxygen fugacity buffer, which in turn increases the pH for a given fO2. The oxidation of ferrous iron during the crystallization of magnetite and hematite is the causal process of sulfate reduction and consequent mineralization. Therefore, the initial pH and fO2 ranges of porphyries favorable for porphyry copper mineralization are defined by the hematite-magnetite oxygen fugacity buffer and SO42--HS--S3- reaction lines. Adakitic rocks have higher initial contents of copper, sulfur and iron than normal arc rocks, and thus are the best candidates for porphyry copper deposits. These provide a plausible explanation for the formation of copper porphyry deposits. The hematite-magnetite intergrowth marks the upper limits of fO2 favorable for the mineralization, and thus may be a powerful tool for future prospecting of large porphyry copper deposits.

Sun, Wei-dong; Liang, Hua-ying; Ling, Ming-xing; Zhan, Mei-zhen; Ding, Xing; Zhang, Hong; Yang, Xiao-yong; Li, Yi-liang; Ireland, Trevor R.; Wei, Qi-rong; Fan, Wei-ming

2013-02-01

378

Rocket having barium release system to create ion clouds in the upper atmosphere  

NASA Technical Reports Server (NTRS)

A chemical system for releasing a good yield of free barium atoms and barium ions to create ion clouds in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium is presented.

Lewis, B. W.; Stokes, C. S.; Smith, E. W.; Murphy, W. J. (inventors)

1974-01-01

379

Enhanced dielectric properties from barium strontium titanate films with strontium titanate buffer layers  

E-print Network

Enhanced dielectric properties from barium strontium titanate films with strontium titanate buffer in their PE state. One of the leading material candidates for tunable materials is barium strontium titanate

Alpay, S. Pamir

380

Some performance characteristics of a solid-state battery composed of Chevrel phase, a copper-ion conductor, and Prussian blue  

Microsoft Academic Search

A solid-state battery composed of copper molybdenum sulphide (Chevrel phase: CP), copperion conductive solid electrolyte, and iron hexacyanoferrate complex (Prussian blue: PB), was studied from the viewpoint of its applicability to a recyclable energy source. The electromotive force increased with the copper content of the CP. The discharge capacity increased with increasing sulphur content as well as copper content of

K. Kuwabara; J. Itoh; K. Sugiyama

1992-01-01

381

Phenotypic and Behavioral Defects Caused by Barium Exposure in Nematode Caenorhabditis elegans  

Microsoft Academic Search

To examine the possible phenotypic defects from barium exposure, a model organism, Caenorhabditis elegans, was chosen to analyze the multiple toxicities in barium-exposed animals. Endpoints of life span, body size, brood size,\\u000a generation time, head thrash, and body bend were selected for the assessment of barium toxicity. High concentrations (75 ?M\\u000a and 200 ?M) of barium exposure caused severe life-span defects. Body

D.-Y. Wang; Y. Wang

2008-01-01

382

Emission spectrographic determination of barium in sea water using a cation exchange concentration procedure  

USGS Publications Warehouse

A concentration technique employing Dowex 50W cation exchange resin is described for the determination of barium in sea water. The separated barium is precipitated as fluoride together with calcium and strontium and measured by emission spectrographic analysis. The vertical distribution of barium in sea water has been measured in the Caribbean Sea and the Atlantic Ocean. The barium content varied between 7 and 23 ??g. per liter; in two profiles, the lowest concentrations were at a depth of about 1000 meters.

Szabo, B. J.; Joensuu, O.

1967-01-01

383

Barium Levels in Soils and Centella asiatica  

PubMed Central

In this study, Centella asiatica and surface soils were collected from 12 sampling sites in Peninsular Malaysia, and the barium (Ba) concentrations were determined. The Ba concentration [?g/g dry weight (dw)] was 63.72 to 382.01 ?g/g in soils while in C. asiatica, Ba concentrations ranged from 5.05 to 21.88 ?g/g for roots, 3.31 to 11.22 ?g/g for leaves and 2.37 to 6.14 ?g/g for stems. In C. asiatica, Ba accumulation was found to be the highest in roots followed by leaves and stems. The correlation coefficients (r) of Ba between plants and soils were found to be significantly positively correlated, with the highest correlation being between roots-soils (r=0.922, p<005), followed by leaves-soils (r=0.890, p<005) and stems-soils (r=0.848, p<005). This indicates that these three parts of C. asiatica are good biomonitors of Ba pollution. For the transplantation study, four sites were selected as unpolluted [(Universiti Putra Malaysia (UPM)], semi-polluted (Seri Kembangan and Balakong) and polluted sites (Juru). Based on the transplantation study under experimental field and laboratory conditions, Ba concentrations in C. asiatica were significantly (p<0.05) higher after three weeks of exposure at Seri Kembangan, Balakong and Juru. Thus, these experimental findings confirm that the leaves, stems and roots of C. asiatica can reflect the Ba levels in the soils where this plant is found. Three weeks after back transplantation to clean soils, the Ba levels in C. asiatica were still higher than the initial Ba level even though Ba elimination occurred. In conclusion, the leaves, stems and roots of C. asiatica are good biomonitors of Ba pollution. PMID:24575242

Ong, Ghim Hock; Yap, Chee Kong; Mahmood, Maziah; Tan, Soon Guan; Hamzah, Suhaimi

2013-01-01

384

Barium Levels in Soils and Centella asiatica.  

PubMed

In this study, Centella asiatica and surface soils were collected from 12 sampling sites in Peninsular Malaysia, and the barium (Ba) concentrations were determined. The Ba concentration [?g/g dry weight (dw)] was 63.72 to 382.01 ?g/g in soils while in C. asiatica, Ba concentrations ranged from 5.05 to 21.88 ?g/g for roots, 3.31 to 11.22 ?g/g for leaves and 2.37 to 6.14 ?g/g for stems. In C. asiatica, Ba accumulation was found to be the highest in roots followed by leaves and stems. The correlation coefficients (r) of Ba between plants and soils were found to be significantly positively correlated, with the highest correlation being between roots-soils (r=0.922, p<005), followed by leaves-soils (r=0.890, p<005) and stems-soils (r=0.848, p<005). This indicates that these three parts of C. asiatica are good biomonitors of Ba pollution. For the transplantation study, four sites were selected as unpolluted [(Universiti Putra Malaysia (UPM)], semi-polluted (Seri Kembangan and Balakong) and polluted sites (Juru). Based on the transplantation study under experimental field and laboratory conditions, Ba concentrations in C. asiatica were significantly (p<0.05) higher after three weeks of exposure at Seri Kembangan, Balakong and Juru. Thus, these experimental findings confirm that the leaves, stems and roots of C. asiatica can reflect the Ba levels in the soils where this plant is found. Three weeks after back transplantation to clean soils, the Ba levels in C. asiatica were still higher than the initial Ba level even though Ba elimination occurred. In conclusion, the leaves, stems and roots of C. asiatica are good biomonitors of Ba pollution. PMID:24575242

Ong, Ghim Hock; Yap, Chee Kong; Mahmood, Maziah; Tan, Soon Guan; Hamzah, Suhaimi

2013-08-01

385

On copper peroxide  

NASA Technical Reports Server (NTRS)

The action of hydrogen superoxide on copper salts in alcoholic solutions is studied. The action of hydrogen peroxide on copper hydroxide in alcoholic suspensions, and the action of ethereal hydrogen peroxide on copper hydroxide are discussed. It is concluded that using the procedure proposed excludes almost entirely the harmful effect of hydrolysis.

Moser, L.

1988-01-01

386

Copper: Technology & Standards  

NSDL National Science Digital Library

This article explains modern copper mining, ore extraction, and casting processes and details innovative copper products, major markets, service activities, and the future of copper in industry and everyday life. It was published in the November 1998 issue of the online magazine Innovations.

Cohen, Art; Association, Copper D.

387

[The evaluation of the presumed mutagenic activity of barium nitrate].  

PubMed

Barium nitrate, which is used in industry in the production of green signal lights, to remove gases from vacuum tubes, and in the production of barium oxide, was assayed to assess the possible mutagenic effects using both the Ames test (S. typhimurium TA 1535, TA 1537, TA 1538, TA 97a, TA 98, TA 100, TA 102c), with and without metabolic activation with the plate incorporation assay and pre-incubation assay methods, and using the mitotic crossing over test, the mitotic genic conversion test, and the retromutation test in Saccharomyces cerevisiae, D7 strain, with and without metabolic activation. In the experimental conditions of the study, at various gradually increasing concentrations, barium nitrate gave negative results. PMID:1803207

Monaco, M; Dominici, R; Barisano, P; Di Palermo, G

1991-01-01

388

Electro-optical polycrystalline barium lanthanum titanium niobate  

SciTech Connect

This patent describes a transparent electro-optic article. It comprises: of a barium lanthanum titanium niobate wherein substantially all grains are of a grain size between about 2 and about 20 micron, the article has a pore volume of less than about 1 percent, and the article has a grain size of between about 2 and about 20 microns. This patent also describes a method of forming transparent electro-optical barium lanthanum titanium niobate. It comprises: providing particles of barium carbonate, lanthanum oxide, titanium oxide, and niobium oxide, calcining the particles, sintering the calcined particles at a temperature of between about 1200{degrees} C and 1300{degrees} C. and a vacuum of between about 10{sup {minus}3} and 10{sup {minus}4} torr while under pressure to form a sintered mass, cooling the sintered mass, slicing the mass to form wafers, heating the wafers in an oxidizing atmosphere.

Mehrotra, A.K.

1991-02-19

389

Appendicitis in children. Accuracy of the barium enema.  

PubMed

The barium enema (BE) may be useful in the diagnosis of atypical appendicitis in children. We analyzed our experience with 18 children in whom appendicitis was suspected and BE was performed. All of the children underwent surgical exploration. Nonfilling of the appendix with cecal indentation, extravasation of barium from the appendix, or both, were considered positive signs of an inflamed appendix on BE. Using these criteria, 12 of 14 cases of proved appendicitis were true positive and two were equivocal. Four children were proved not to have appendicitis; one of these patients had a true-negative BE, two had equivocal BEs, and there was one false-positive BE (Schönlein-Henoch purpura). Extravasation of barium into the peritoneal cavity was noted in one patient; this was a rare complication. PMID:3687874

Garcia, C; Rosenfield, N S; Markowitz, R I; Seashore, J H; Touloukian, R J; Cicchetti, D V

1987-12-01

390

Multiphoton laser ionization for energy conversion in barium vapor  

NASA Astrophysics Data System (ADS)

We have studied the ion detection of barium atoms in special heated ovens with a tungsten rod in the middle of the stainless steel tube. The tungsten rod was heated indirectly by the oven body heaters. A bias voltage between the cell body and the tungsten rod of 9 V was used to collect electrons, after the barium ions had been created. However, we could collect the electrons even without the bias voltage, although with ten times less efficiency. We studied the conditions for the successful bias-less thermionic signal detection using excimer/dye laser two-photon excitation of Rydberg states below and above the first ionization limit (two-photon wavelength at 475.79 nm). We employed a hot-pipe oven and heat-pipe oven (with inserted mesh) in order to generate different barium vapor distributions inside the oven. The thermionic signal increased by a factor of two under heat-pipe oven conditions.

Makdisi, Y.; Kokaj, J.; Afrousheh, K.; Mathew, J.; Nair, R.; Pichler, G.

2013-03-01

391

The Contact Difference of Potential Between Barium and Zinc The External Work Function of Zinc  

Microsoft Academic Search

The methods of contact potential measurement described in previous reports of this series have been extended to zinc, for which the published work function data are discordant. Measurement was by the retarding potential method with variable anode, in tubes sealed from the pumps and gettered with vaporized barium. Barium was the reference metal and the measured surfaces of both barium

Paul A. Anderson

1940-01-01

392

Sputtering of a hydrogenated barium surface in a negative ion surface conversion source  

Microsoft Academic Search

Both the production of negative hydrogen ions on a barium surface and surface sputtering under low energy (~ 200 eV) intense particle bombardment is studied in the FOM Surface Conversion Experiment. We have observed a decrease in barium sputter-yield when a barium surface is exposed to an intense positive hydrogen or deuterium ion flux, extracted from a plasma. This effect

R. M. A. Heeren; D. Ciric; S. Yagura; H. J. Hopman; A. W. Kleyn

1992-01-01

393

Barium Titanate Nanoparticles in Block Copolymer Tu Lee,*,, Nan Yao, Hiroaki Imai,, and Ilhan A. Aksay,  

E-print Network

Barium Titanate Nanoparticles in Block Copolymer Tu Lee,*,, Nan Yao, Hiroaki Imai,, and Ilhan A-polybutadiene-polystyrene (Kraton D1102). The barium titanated Kraton thin film had remnants of the cylindrical morphology of a plain Kraton thin film with an interdomain spacing of 23 nm. The procedure of barium titanation

Aksay, Ilhan A.

394

Discrete Barium Strontium Titanate (BST) Thin-Film Interdigital Varactors on Alumina: Design, Fabrication, Characterization, and  

E-print Network

Discrete Barium Strontium Titanate (BST) Thin-Film Interdigital Varactors on Alumina: Design, Raleigh, NC-27695-7914, USA. Email:jayeshnath@ieee.org Abstract -- Discrete Barium Strontium Titanate (BST, capacitors, BST, ferroelectric, thin-film, barium strontium titanate, bandpass filter, IP3, ACPR, temperature

395

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

...2014-07-01 2014-07-01 false Barium manganese oxide (BaMnO3). 721.10010 Section...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3 ). (a) Chemical...chemical substance identified as barium manganese oxide (BaMnO3 ) (PMN...

2014-07-01

396

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Barium manganese oxide (BaMnO3). 721.10010 Section...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3 ). (a) Chemical...chemical substance identified as barium manganese oxide (BaMnO3 ) (PMN...

2013-07-01

397

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721.10010 Section...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical...chemical substance identified as barium manganese oxide (BaMnO3 ) (PMN...

2010-07-01

398

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Barium manganese oxide (BaMnO3). 721.10010 Section...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical...chemical substance identified as barium manganese oxide (BaMnO3 ) (PMN...

2011-07-01

399

40 CFR 721.10010 - Barium manganese oxide (BaMnO3).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Barium manganese oxide (BaMnO3). 721.10010 Section...Chemical Substances § 721.10010 Barium manganese oxide (BaMnO3 ). (a) Chemical...chemical substance identified as barium manganese oxide (BaMnO3 ) (PMN...

2012-07-01

400

Compact pulse forming line using barium titanate ceramic material  

NASA Astrophysics Data System (ADS)

Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO3) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 ? load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber.

Kumar Sharma, Surender; Deb, P.; Shukla, R.; Prabaharan, T.; Shyam, A.

2011-11-01

401

Iron deficiency  

Microsoft Academic Search

Iron deficiency remains one of the world’s greatest public health problems. Globally it is the greatest contributor to anaemia, affecting 47% of pre-school age children and 25% of school age children worldwide, and is a major contributor to both physical and neuro-developmental morbidity.Iron deficiency results from inadequate intake, excess turnover or excessive loss. Whilst inadequate intake is the commonest cause

Katrina Pettit; Jennifer Rowley; Nick Brown

2011-01-01

402

Effect of Magnetic-Dielectric Interface on Capacitor Functions of Fe-Doped Barium Titanate Nanocomposites at Low Frequency ( < 1 MHz)  

NASA Astrophysics Data System (ADS)

Metal-dielectric interfaces have been shown to greatly influence the capacitor functions of nanodielectric composites. However, the effect of magnetic metal impurities in nanocomposites on dielectric properties is not well understood. Nanodielectric composites of iron in off stoichiometric barium titanate were fabricated by sol-gel process with varying pH concentrations. The fabricated samples containing 1-2% iron reveal unique interfacial structure as studied by X-ray and atomic force microscopy. The capacitance of the as prepared samples was measured with an Agilent LCR meter at frequencies ranging from 20 Hz to 1 MHz. All nanodielectric composites show similar capacitor characteristic and reveal continuous decrease in capacitor density with increasing frequency. For a particular sample, this continuous decrease is a direct result of the porous interface between the iron granules and the dielectric material. This behavior, however, is not measurably influenced by an applied magnetic field in all samples.

Chowdhury, Ataur; Kulkarni, Kapil; Sarkar, Gautam

2012-02-01

403

Study of the photovoltaic effect in thin film barium titanate  

NASA Technical Reports Server (NTRS)

The photoelectric effect in structures consisting of metal deposited barium titanate film silicon is described. A radio frequency sputtering technique is used to deposit ferroelectric barium titantate films on silicon and quartz. Film properties are measured and correlated with the photoelectric effect characteristics of the films. It was found that to obtain good quality pin hole free films, it is necessary to reduce the substrate temperature during the last part of the deposition. The switching ability of the device with internal applied voltage is improved when applied with a ferroelectric memory device.

Grannemann, W. W.; Dharmadhikari, V. S.

1981-01-01

404

Ionization and expansion of barium clouds in the ionosphere  

NASA Technical Reports Server (NTRS)

A recently envelope 3D model is used here to study the motion of the barium clouds released in the ionosphere, including the ionization stage. The ionization and the expansion of the barium clouds and the interaction between the clouds and the background ions are investigated using three simulations: a cloud without a directional velocity, a cloud with an initial velocity of 5 km/s across the B field, and a cloud with initial velocity components of 2 km/s both along and across the B field.

Ma, T.-Z.; Schunk, R. W.

1993-01-01

405

Methods for producing monodispersed particles of barium titanate  

DOEpatents

The present invention is a low-temperature controlled method for producing high-quality, ultrafine monodispersed nanocrystalline microsphere powders of barium titanate and other pure or composite oxide materials having particles ranging from nanosized to micronsized particles. The method of the subject invention comprises a two-stage process. The first stage produces high quality monodispersed hydrous titania microsphere particles prepared by homogeneous precipitation via dielectric tuning in alcohol-water mixed solutions of inorganic salts. Titanium tetrachloride is used as an inorganic salt precursor material. The second stage converts the pure hydrous titania microsphere particles into crystalline barium titanate microsphere powders via low-temperature, hydrothermal reactions.

Hu, Zhong-Cheng (Knoxville, TN)

2001-01-01

406

Method of producing highly oxidized superconductors containing barium, copper, and a third metal  

DOEpatents

Novel superconducting materials in the form of compounds, structures or phases are formed by performing otherwise known syntheses in a highly oxidizing atmosphere rather than that created by molecular oxygen at atmospheric pressure or below. This leads to the successful synthesis of novel superconducting compounds which are thermodynamically stable at the conditions under which they are formed. 16 figs.

Morris, D.E.

1996-02-20

407

SQUID measurements of magnetic vortices in very underdoped yttrium-barium-copper-oxide  

NASA Astrophysics Data System (ADS)

This dissertation describes the first demonstration of a scanning Superconducting QUantum Interference Device (SQUID) susceptometer---a new tool for the study of local magnetic properties of materials---and applies it to a series of studies of vortices in the cuprate superconductor YBa2Cu 3O6+x. The susceptometer is comprised of a scanning SQUID with an 8mum pickup loop and an integrated 21mum diameter field coil for applying a local magnetic field. We test the system by measuring the susceptibility of individual 3mum diameter tin disks. The spatial resolution of the device is 8mum, set by the size of the pickup loop, and the low-field spin sensitivity between 1.5 and 6K is 1 x 105muB/ Hz while scanning. The susceptometer is applied to the controlled, reversible manipulation of individual vortices using a locally applied magnetic field, with the SQUID used to image the vortices before and after moving. We calculate the force applied on a rigid vortex and find that ˜0.5pN is necessary to move vortices in underdoped single crystals of YBa2Cu3O6+ x with Tc ˜ 12K. Locally applied magnetic fields from the susceptometer can create vortex-antivortex pairs which typically annihilate on some timescale depending on temperature. Observations of annihilations at different locations in a sample of highly underdoped YBa2Cu3O6+x are used to infer the qualitative nature of the local pinning landscape. We find pinning sites have a wide range of energies, with deep pinning sites distributed on a length scale of microns. The distribution of annihilation times as a function of temperature did not fit a simple picture of thermal activation, suggesting that pinning is complicated. We performed the spin charge separation experiment proposed by Senthil and Fisher, in which a topological excitation known as a vison was predicted to cause a vortex memory effect in a ring of cuprate superconductor. We detected no signature of the proposed vison and use this result to place a conservative upper limit on the vison energy of 190K·kB. The theory predicts a vison energy on the order of 500--700K· kB for our samples. As a result, spin-charge separation theories requiring visons seem unlikely as an explanation of cuprate superconductivity. Finally, we report measurements of single vortex dynamics in a superconducting YBa2Cu3O6+x ring. We found robust intermediate states between the expected states of n and n + 1 vortices in the ring. The temperature dependence of transitions between states was consistent with thermal activation over a barrier much lower than would be expected for a rigid vortex moving across the ring wall. We conjecture that vortices in our ring behave as stacks of pancake vortices and that intermediate states were due to split stacks in with some pancake vortices remaining inside the ring, while some escape outside.

Gardner, Brian Willard

408

Physical Properties of Oxygen Deficient YTTRIUM(1) BARIUM(2) COPPER(3) OXYGEN(7-DELTA) Superconductors.  

NASA Astrophysics Data System (ADS)

The physical properties of oxygen deficient polycrystalline rm YBa_2Cu_3O_{7 -delta} superconducting materials have been systematically investigated. These properties include magnetic susceptibility, electrical transport, thermoelectric power and infrared reflectivity. A great deal of this study has concentrated on the magnetic and transport properties of these materials when they are in the mixed state. The polycrystalline specimens used in this work were prepared through a solid state reaction. The oxygen content of the specimens was controlled using several annealing methods and the oxygen deficiency delta was determined by X-ray diffraction, gas evolution, iodometric titration and neutron diffraction techniques. A new method has been developed for the investigation of magnetic relaxation in these materials using the conventional a.c. susceptibility technique after modification. This thesis represents the first detailed and systematic study of the thermal activation energy for high Tc superconductors using many different methods, including a.c. susceptibility, magnetic relaxation, electric resistivity and thermoelectric power. All the results obtained, including their numerical values and field dependence are consistent with and comparable to previously reported data. A modified critical state model has been successfully used to interpret the magnetic field dependence of the isothermal a.c. susceptibility data, including field dependent a.c. losses and the chi^' -chi^{'' } interrelationship. This study highlights the strong influence that delta exerts on the superconducting and normal state properties of polycrystalline rm YBa_2Cu_3O_{7-delta } material. In particular, for transport properties, delta affects the carrier doping in the CuO_2 planes, which determines the carrier concentration. Therefore increasing delta reduces the superconducting transition temperature. For the magnetic property, delta has a negative influence on the pinning energy in polycrystalline material and therefore reduces the critical current density. The infrared reflectivity spectra and extracted dielectric function show a dramatic change in the longitudinal and transverse mode structure of these materials which occurs when oxygen is removed from the chain sites.

Sun, He Bi.

409

Preparation and Microstructural Characterization of Yttrium Barium Copper Oxygen Superconducting Thin Films  

NASA Astrophysics Data System (ADS)

The preparation and microstructural characterization of YBaCuO superconducting thin films are described. The films were deposited onto various substrates by flash evaporation and rf magnetron sputtering methods. The flash evaporation was made by dropping powders of sintered Y_1Ba_2Cu _3O_{rm 7-x} onto a resistively heated W boat. A sintered powder target was used for the rf magnetron sputtering. In the latter case, use of buffer layers of SrTiO _3 resulted in (00l) oriented films that were superconducting in the as-deposited state. These films and others deposited on various substrates were subsequently annealed in O_2 to improve both superconducting and microstructural properties. When the annealing temperatures were very high (>900C) the films started to degrade structurally and the T _{rm c}'s of the films were found to be sensitive to this degradation. The characterization techniques included X-ray diffractometry (XRD), X-ray energy spectroscopy (XES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), reflection high energy electron diffraction (RHEED) and the measurement of the temperature dependent electrical resistance by a four probe method. Integral breadth X-ray diffraction line broadening from the films having an (00l) texture was investigated. Changes in the broadening of the 00l diffraction lines were attributed to changes in nonuniform strain along the c -direction, since the crystallite size in a direction perpendicular to the film plane did not change much. These results were correlated with annealing temperatures and electrical resistance measurements of the YBaCuO films. An average lattice parameter c was calculated from the peak positions of the 00 l diffraction lines. The as-deposited films had an elongated lattice parameter c in a direction perpendicular to the film plane and it decreased on annealing. The T _{rm c}'s of the films were found to be sensitive to this change. It was also observed that annealing improved the texture and caused lateral grain growth in the films.

Ece, Muzeyyen

410

Flux Creep Studies in YTTRIUM(1) BARIUM(2) COPPER(3) OXIDE(7-DELTA) Superconductors  

NASA Astrophysics Data System (ADS)

Magnetic relaxation studies were performed on a proton irradiated high J_{c} YBa_2Cu _3O_{7-delta} single crystal and a melt-texture-growth YBa _2Cu_3O_ {7-delta} sample. Significant deviation from the logarithmic time decay predicted by conventional Anderson-Kim theory was observed for a wide range of temperature and magnetic field. The flux creep data, with durations up to 3.5 times 10^5 s, could be analyzed using several recent models with comparable accuracies. The difficulty in distinguishing between these models is due to the fact that the time window of observations, which usually covers ~2 or 3 decades, is too short for magnetic relaxation studies. To complement these studies in the direct time domain, the effects of field-sweep rate K = partial H/partialt on magnetization hysteresis loops M(H) and on flux-creep M(t) were investigated both theoretically and experimentally. We find the basic relation between M and K is, to first order, the following: M = const - (dM/dln(t)) ln(K) - (Kt_{ eff}/10), where dM/dln(t) = ac/30 is the flux-creep rate in a cylindrical sample of radius a, and t_{eff} is an effective attempt time for vortex hopping. The largest possible M, which corresponds to the critical current density J_{c0} in the absence of thermal activation, develops when at high sweep rate K >= K_{ max} = ac/ ((1 + aalpha )t_{eff}) with alpha = partial J/partialH. Such studies provided a way to measure t_{eff}, whose magnitude has been rather controversial; furthermore, the analysis revealed the time origin of flux creep, t* = ac/K(1 + aalpha), which is essential in studying the initial stages of relaxation. The model agrees well with experiments yielding t_ {eff}~0.2 s for the melt -textured-growth sample. By combining conventional flux creep experiments with measurements of magnetization versus magnetic field sweep rate, we are able to detect the decay of magnetization in both its middle and very early stages, thereby expanding the observational time window up to 5~ 6 decades. Among four models tested, only Vortex -Glass/Collective-Pinning theory gives a consistent description of both stages.

Sun, Yang Ren

411

Low Frequency Electrical Noise in Bulk Yttrium BARIUM(2)COPPER(3)OXYGEN(7)  

NASA Astrophysics Data System (ADS)

The current induced, low frequency electrical noise properties of bulk YBa_{2} Cu_{3}O _{7} are experimentally investigated from well below the superconducting transition temperature, through the superconductor to normal conductor transition region, and on up to room temperature. No noise is detected deep within the superconducting state. Noise with a voltage spectral density that varies approximately as l/f, appears high on the "resistive tail" that is associated with the lower half of the transition region. As temperature is increased, the normalized noise level is seen to peak right at the top of the tail, decrease abruptly throughout the remainder of the transition region, and then decrease more gradually on up to room temperature. The noise level scales as V^{beta}, beta > 2, on the resistive tail side of the noise peak. On the normal state side of the noise peak, the level scales as V^ {2}. This finding indicates that two different noise generation mechanisms are present, and it is suggested that the resistive tail noise is due to the irregular motion of Abrikosov flux vortices. Individual crystals of YBa_{2 }Cu_{3}O _{7} contain one plane in which the superconducting properties are isotropic, and two planes in which the superconducting properties are equivalently anisotropic. The formation of a vortex with its core perpendicular to an anisotropic plane requires less energy than does the formation of a vortex with its core perpendicular to an isotropic plane. London theory solutions are obtained for the magnetic flux and supercurrent densities around an anisotropic vortex, and that type of vortex is found to be elliptical in shape. In addition, the London solution predicts an effective interchange of London penetration depths from one axis of the ellipse to the other. A derivation of the thermal noise in a gas of non-interacting charged bosons (ie.-the thermal noise inside a superconductor) is also included. In this model the superconducting transition temperature, T_ {c}, is identified with the Einstein condensation temperature. Above T_{c}, the thermal noise is seen to be identical to the thermal noise in an ordinary conductor. Below T_ {c}, the thermal noise falls off as the number of bosons in excited states falls off.

Hickman, Hugh V.

412

Alternating current loss characteristics in (bismuth,lead)SCCO and yttrium barium copper oxide superconducting tapes  

NASA Astrophysics Data System (ADS)

Alternating current (AC) loss and current carrying capacity are two of the most crucial considerations in large-scale power applications of high temperature superconducting (HTS) conductors. AC losses result in an increased thermal load for cooling machines, and thus increased operating costs. Furthermore, AC losses can stimulate quenching phenomena or at least decrease the stability margin for superconducting devices. Thus, understanding AC losses is essential for the development of HTS AC applications. The main focus of this dissertation is to make reliable total AC loss measurements and interpret the experimental results in a theoretical framework. With a specially designed magnet, advanced total AC loss measurement system in liquid nitrogen (77 K) has been successfully built. Both calorimetric and electromagnetic methods were employed to confirm the validity of the measured results and to have a more thorough understanding of AC loss in HTS conductors. The measurement is capable of measuring total AC loss in HTS tapes over a wide range of frequency and amplitude of transport current and magnetic field. An accurate phase control technique allows measurement of total AC loss with any phase difference between the transport current and magnetic field by calorimetric method. In addition, a novel total AC loss measurement system with variable temperatures from 30 K to 100 K was successfully built and tested. Understanding the dependence of AC losses on temperature will enable optimization of the operating temperature and design of HTS devices. As a part of the dissertation, numerical calculations using Brandt's model were developed to study electrodynamics and total AC loss in HTS conductors. In the calculations, the superconducting electrical behavior is assumed to follow a power-law model. In general, the practical properties of conductors, including field-dependence of critical current density Jc, n-value and non-uniform distribution of Jc, can be accounted for in the numerical calculations. The numerical calculations are also capable of investigating eddy current loss in the stabilizer and ferromagnetic loss in the substrate of YBa2Cu3O 7-delta (YBCO) coated conductor. AC loss characteristics and electrodynamics in several (Bi,Pb)2 Sr2Ca2Cu3Ox (Bi-2223) and YBCO tapes were studied experimentally and numerically. It was found that AC loss behavior Ax in HTS tapes is strongly affected by the sample parameters such as cross-section, structure, dimensions, critical current distribution as well as by operation parameters including temperature, frequency, the phase difference between transport current and magnetic field, the orientation of magnetic field. The Ni-5%W substrate in YBCO conductors generates some ferromagnetic loss but this loss component is significantly reduced by a small parallel DC magnetic field. At a given AC magnetic field B0, there is a temperature Tmax at which the magnetization loss is maximum. The design of HTS devices needs to be optimized to avoid operating at that temperature. In general, the total AC loss in HTS tapes is still high for many power device applications, especially for those that present a rather high AC applied magnetic field. The development of low loss conductors is therefore crucial for HTS large-scale applications.

Nguyen, Doan Ngoc

413

Rare earth erbium doped yttrium barium copper oxide superconducting domains and their magnetic properties  

NASA Astrophysics Data System (ADS)

The starting composition and structure of YBa2Cu3O 7-1 (Y123) ceramic powder with excess Y2BaCuO 5 is shown to be very important to successful processing of large single domain bulk Y123 material. Besides composition and structure it is shown that the setter and the setup of the setter are essential for the elimination of liquid loss and a key ingredient in the Robust Processing Method (RPM). The RPM was used to examine the effect on processing of high Erbium (Er) additions (60 mol/percent) to YBa2Cu3O7-1. The effect on microstructure, and the superconducting properties of the resulting material were also examined. The superconducting properties that were examined were the bulk-trapped magnetic field, the Critical Transition Temperature (Tc) and the Critical Current (Jc) in a changing applied magnetic field. The bulk-trapped fields were found to be unimproved due to decomposition of the SmBa2Cu3O7-1 (Sm123) seed during processing which causes sporadic crystallization during the growth cycle. Tc's of the textured resulting material were found to be relatively unaffected when compared to unadulterated Y123, while Jc's were found to increase with accelerated processing rate when compared to unadulterated Y123.

Hicks, William Carl

414

Anisotropic superconductivity observed by magneto-optical imaging: A case study of yttrium barium copper oxide  

NASA Astrophysics Data System (ADS)

This work studies direct Magneto-Optical Imaging (MOI) as a means to directly observe anisotropic superconductivity using (110)-oriented YBa 2Cu3O7-delta (YBCO) thin film. The MOI technique can translate magnetic field distribution directly into an optical image. It has been used to study supercurrent distribution in a superconducting thin film. A fast Fourier transform method was developed to convert the MO image into maps of current density distribution independent of the underlying models that are used to extract the critical current densities. By using this method, the inhomogeneous critical current distribution can be deduced, and current stream maps can be constructed. High quality single phase YBCO (110) thin films were fabricated by magnetron sputtering. Characterizations by X-ray diffraction, Rutherford backscattering and channeling, a scanning electron microscope, an atomic force microscope, and electric transport measurement indicates that the (110) films are single-phased, strain-free, highly oxygenated, and have a relatively smooth surface compared to the c-axis oriented counterpart prepared by the same technique. Direct imaging of the anisotropic magnetic field distribution at the surface of YBCO (110) thin film has been realized, where the unique stripe-like pattern is interpreted as based on the anisotropic critical current density model developed in this work. Geometric effects on anisotropic critical current flow have been examined. The characteristic behaviors of parabola-shaped discontinuity-lines (d-line) in an anisotropic thin film sample are discussed. Calculations of the critical currents at step-edged defects on anisotropic thin-films strip were conducted. The magnetic field pattern derived from the calculation is in good agreement with the stripe pattern of the experiment. Such step-edges are representative of physical imperfections that dictate the presence or absence of the stripe pattern in an anisotropic superconductor.

Wang, Chong

415

Electromagnetic properties and engineering applications of single-domain high temperature superconductor yttrium barium copper oxide  

Microsoft Academic Search

High temperature superconductors (HTS) exhibit a commonly known Meissner effect, which can cause a unusually strong magnetic repulsion. Using this effect, magnetic bearings have been constructed with 1000 times less friction than that of conventional bearings. The commercialization of the flywheel energy storage device (FESD) could mean cost-savings for the electric power industry. For instance, using a flywheel device, the

Dehui Qu

2000-01-01

416

Highly-textured thallium-barium-calcium-copper-oxide polycrystalline superconducting films on silver substrates  

SciTech Connect

Thick (8 to 10 {mu}m) Ba--Ca--Cu--O films have been rf magnetron sputtered onto Ag alloy (Consil 995) substrates. The films were given a post-deposition anneal in an over pressure of Tl in order to form the superconducting phases. Annealing protocols were done which result in predominantly the 1212 and 2212 phases. The substrate orientation was varied to determine its effect on film orientation. Material properties of the films were characterized by x-ray diffraction (XRD), ion beam backscattering spectroscopy, energy dispersive x-ray analysis (EDAX), and scanning electron microscopy (SEM). Electrical characterization of the films was done using dynamic impedance (DI) at 10 kHz and rf surface resistance (R{sub s}) at 18 GHz in a TE{sub 011} fundamental mode cavity. 19 refs., 7 figs.

Arendt, P.; Elliott, N.; Cooke, D.W.; Dye, R.; Gray, E.; Hubbard, K.; Martin, J.; Reeves, G.; Brown, D.; Klapetzky, A.

1990-01-01

417

Yttrium Barium Copper Oxide: the Formulation and Magnetic Properties of a 93 K Superconductor  

NASA Astrophysics Data System (ADS)

The focus of this thesis is a systematic study of the relationship between the oxygen stoichiometry and the highly anisotropic magnetic behavior of single crystals of YBa_2Cu_3O _{rm 7-y} ("Y123"). While these two areas have received much attention individually, the body of knowledge relating them is scant. The principal objective of this work is to evaluate the dependence of such microscopic parameters as lower critical fields and critical current densities on the oxygen deficiency y. Correlations between oxygen stoichiometry and the lower critical fields are expected since the latter is to a good approximation directly proportional to the superconducting carrier density; this, in turn, is a strong function of the oxygen-regulated normal carrier density. The critical current densities are expected to have a strong dependence on oxygen since flux pinning on microstructural defects such as twinning regulates the time rate of decay of the currents; twinning in Y123 is dictated by oxygen stoichiometry and processing conditions. Independent of all other factors, the oxygen stoichiometry can be adjusted to completely eliminate twins or to render the material insulating. By testing single crystals, the anisotropy of these parameters is also studied, from which inferences are drawn on the nature of the pinning mechanisms. In addition to the above, an accurate account and detailed evaluation of the author's ideas and motivation responsible for the original formulation of Y-Ba-Cu-O is given.

Ashburn, James Robert

1990-01-01

418

The Fabrication and Performance of Yttrium BARIUM(2) COPPER(3) OXYGEN(7-X) SQUID Magnetometers  

NASA Astrophysics Data System (ADS)

A thin-film planar dc Superconducting QUantum Interference Device (SQUID) is a very sensitive detector of changes in magnetic field, but noise considerations require that it have a small pick-up area, and consequently a relatively poor intrinsic sensitivity to magnetic fields. To enhance the SQUID's field sensitivity, one invariably couples it to a flux transformer, a closed superconducting circuit consisting of a pickup loop, to which a signal is applied, connected in series to an input coil, which is inductively coupled to the SQUID. To fabricate an optimal flux transformer, one whose input coil has multiple turns, one must use more than one superconducting thin-film layer, each of which is patterned into narrow strips or wires. In some places, it is necessary that wires from different layers cross, yet remain electrically isolated, to form crossovers, while in other places there must be superconducting contact between wires from different layers. Together, the superconducting wire, the superconducting-superconducting contact and the superconducting crossover constitute a superconducting interconnect or multilayer wiring technology that is an essential part of a complete superconducting microelectronics technology. We discuss the development of an interconnect technology involving the high transition temperature (T _{c}) superconductor YBa_2Cu_3O _{7-x} (YBCO). Because of the overriding need for epitaxial growth of YBCO thin films, there are strict limitations placed on the materials available for u