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Sample records for iron surface determinant

  1. Iron-regulated surface determinant (Isd) proteins of Staphylococcus lugdunensis.

    Science.gov (United States)

    Zapotoczna, Marta; Heilbronner, Simon; Speziale, Pietro; Foster, Timothy J

    2012-12-01

    Staphylococcus lugdunensis is the only coagulase-negative Staphylococcus species with a locus encoding iron-regulated surface determinant (Isd) proteins. In Staphylococcus aureus, the Isd proteins capture heme from hemoglobin and transfer it across the wall to a membrane-bound transporter, which delivers it into the cytoplasm, where heme oxygenases release iron. The Isd proteins of S. lugdunensis are expressed under iron-restricted conditions. We propose that S. lugdunensis IsdB and IsdC proteins perform the same functions as those of S. aureus. S. lugdunensis IsdB is the only hemoglobin receptor within the isd locus. It specifically binds human hemoglobin with a dissociation constant (K(d)) of 23 nM and transfers heme on IsdC. IsdB expression promotes bacterial growth in an iron-limited medium containing human hemoglobin but not mouse hemoglobin. This correlates with weak binding of IsdB to mouse hemoglobin in vitro. Unlike IsdB and IsdC, the proteins IsdJ and IsdK are not sorted to the cell wall in S. lugdunensis. In contrast, IsdJ expressed in S. aureus and Lactococcus lactis is anchored to peptidoglycan, suggesting that S. lugdunensis sortases may differ in signal recognition or could be defective. IsdJ and IsdK are present in the culture supernatant, suggesting that they could acquire heme from the external milieu. The IsdA protein of S. aureus protects bacteria from bactericidal lipids due to its hydrophilic C-terminal domain. IsdJ has a similar region and protected S. aureus and L. lactis as efficiently as IsdA but, possibly due to its location, was less effective in its natural host.

  2. Iron oxide surfaces

    Science.gov (United States)

    Parkinson, Gareth S.

    2016-03-01

    known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Feoct-O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10-7-10-5 mbar O2 in the final stage of preparation. Such straightforward preparation of a monophase termination is generally not the case for iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch-Cohen defects in Fe1-xO. The cation deficiency results in Fe11O16 stoichiometry, which is in line with the chemical potential in ultra-high vacuum (UHV), which is close to the border between the Fe3O4 and Fe2O3 phases. The Fe3O4(111) surface is also much studied, but two different surface terminations exist close in energy and can coexist, which makes sample preparation and data interpretation somewhat tricky. Both the Fe3O4(100) and Fe3O4(111) surfaces exhibit Fe-rich terminations as the sample selvedge becomes reduced. The Fe3O4(110) surface forms a one-dimensional (1×3) reconstruction linked to nanofaceting, which exposes the more stable Fe3O4(111) surface. α-Fe2O3(0001) is the most studied haematite surface, but difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called "bi-phase" structure is formed, which eventually transforms to a Fe3O4(111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe1-xO and α-Fe2O3(0001) islands

  3. Iron cycling at corroding carbon steel surfaces.

    Science.gov (United States)

    Lee, Jason S; McBeth, Joyce M; Ray, Richard I; Little, Brenda J; Emerson, David

    2013-01-01

    Surfaces of carbon steel (CS) exposed to mixed cultures of iron-oxidizing bacteria (FeOB) and dissimilatory iron-reducing bacteria (FeRB) in seawater media under aerobic conditions were rougher than surfaces of CS exposed to pure cultures of either type of microorganism. The roughened surface, demonstrated by profilometry, is an indication of loss of metal from the surface. In the presence of CS, aerobically grown FeOB produced tight, twisted helical stalks encrusted with iron oxides. When CS was exposed anaerobically in the presence of FeRB, some surface oxides were removed. However, when the same FeOB and FeRB were grown together in an aerobic medium, FeOB stalks were less encrusted with iron oxides and appeared less tightly coiled. These observations suggest that iron oxides on the stalks were reduced and solubilized by the FeRB. Roughened surfaces of CS and denuded stalks were replicated with culture combinations of different species of FeOB and FeRB under three experimental conditions. Measurements of electrochemical polarization resistance established different rates of corrosion of CS in aerobic and anaerobic media, but could not differentiate rate differences between sterile controls and inoculated exposures for a given bulk concentration of dissolved oxygen. Similarly, total iron in the electrolyte could not be used to differentiate treatments. The experiments demonstrate the potential for iron cycling (oxidation and reduction) on corroding CS in aerobic seawater media.

  4. Rate and extent of aqueous perchlorate removal by iron surfaces.

    Science.gov (United States)

    Moore, Angela M; De Leon, Corinne H; Young, Thomas M

    2003-07-15

    The rate and extent of perchlorate reduction on several types of iron metal was studied in batch and column reactors. Mass balances performed on the batch experiments indicate that perchlorate is initially sorbed to the iron surface, followed by a reduction to chloride. Perchlorate removal was proportional to the iron dosage in the batch reactors, with up to 66% removal in 336 h in the highest dosage system (1.25 g mL(-1)). Surface-normalized reaction rates among three commercial sources of iron filings were similar for acid-washed samples. The most significant perchlorate removal occurred in solutions with slightly acidic or near-neutral initial pH values. Surface mediation of the reaction is supported by the absence of reduction in batch experiments with soluble Fe2+ and also by the similarity in specific reaction rate constants (kSA) determined for three different iron types. Elevated soluble chloride concentrations significantly inhibited perchlorate reduction, and lower removal rates were observed for iron samples with higher amounts of background chloride contamination. Perchlorate reduction was not observed on electrolytic sources of iron or on a mixed-phase oxide (Fe3O4), suggesting that the reactive iron phase is neither pure zerovalent iron nor the mixed oxide alone. A mixed valence iron hydr(oxide) coating or a sorbed Fe2+ surface complex represent the most likely sites for the reaction. The observed reaction rates are too slow for immediate use in remediation system design, but the findings may provide a basis for future development of cost-effective abiotic perchlorate removal techniques.

  5. Surface magnetism in iron, cobalt, and nickel

    DEFF Research Database (Denmark)

    Alde´n, M.; Mirbt, S.; Skriver, Hans Lomholt

    1992-01-01

    We have calculated magnetic moments, work functions, and surface energies for several of the most closely packed surfaces of iron, cobalt, and nickel by means of a spin-polarized Green’s-function technique based on the linear muffin-tin orbitals method within the tight-binding and atomic sphere...

  6. Characterization of the mechanism of protection mediated by CS-D7, a monoclonal antibody to Staphylococcus aureus iron regulated surface determinant B (IsdB

    Directory of Open Access Journals (Sweden)

    Gregory ePancari

    2012-03-01

    Full Text Available We previously reported the development of a human monoclonal antibody (CS-D7, IgG1 with specificity and affinity for the iron regulated surface determinant B (IsdB of Staphylococcus aureus. CS-D7 mediates opsonophagocytic killing in vitro and protection in a murine sepsis model. In light of recent data indicating that IsdB specific T cells (CD4+, Th17, not Ab, mediate protection after vaccination with IsdB, it is important to investigate the mechanism of protection mediated by CS-D7. The mAb was examined to determine if it blocked heme binding to IsdB in vitro. The mAb was not found to have heme blocking activity, nor did it prevent bacterial growth under in vivo conditions, in an implanted growth chamber. To assess the role of the mAb Fc a point mutation was introduced at aa 297 (CS-D7●N297A. This point mutation removes Fc effector functions. In vitro analysis of the mutein confirmed that it lacked measurable binding to FcγR, and that it did not fix complement. The mutein had dramatically reduced in vitro opsonic OP activity compared to CS-D7. Nonetheless, the mutein conferred protection equivalent to the wild type mAb in the murine sepsis model. Both wild type and mutein mAbs were efficacious in FcγR deletion mice (including both FcγRII-/- mice and FcγRIII-/- mice, indicating that these receptors were not essential for mAb mediated protection in vivo. Protection mediated by CS-D7 was lost in Balb/c mice depleted of C3 with cobra venom factor (CFV, was lost in mice depleted of superoxide dismutase (SOD in P47phox deletion mice, and was absent in SCID mice. Enhanced clearance of S. aureus in the liver of CS-D7 treated mice and enhanced production of INF-γ, but not of IL17, may play a role in the mechanism of protection mediated by the mAb. CS-D7 apparently mediates survival in challenged mice through a mechanism involving complement, phagocytes, and lymphocytes, but which does not depend on interaction with FcγR, or on blocking heme

  7. Surface effects in metallic iron nanoparticles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Linderoth, Søren

    1994-01-01

    Nanoparticles of metallic iron on carbon supports have been studied in situ by use of Mossbauer spectroscopy. The magnetic anisotropy energy constant increases with decreasing particle size, presumably because of the influence of surface anisotropy. Chemisorption of oxygen results in formation...... of a surface layer with magnetic hyperfine fields similar to those of thicker passivation layers, and with a ferromagnetic coupling to the spins in the core of the particles. In contrast, thicker passivation layers have a noncollinear spin structure....

  8. Determination of Coil Inductances Cylindrical Iron Nucleus

    Directory of Open Access Journals (Sweden)

    Azeddine Mazouz

    2014-03-01

    Full Text Available The paper describes the investigation and development of a structure and performance characteristics of a coil iron nucleus cylindrical (C.I.N.C. The coil iron nucleus cylindrical is a nonlinear electro radio in which the moving of the nucleus in a sense or in other causes change in inductance and can reach extreme values at the superposition of nucleus and coil centers. The variation of the inductance and the degree of freedom of movement of the nucleus can lead to a device with electromechanical conversion The aim of this paper is the determination and visualization of self inductance and mutual of the (C.I.N.C based on geometric dimensions and the displacement of the nucleus.  

  9. Relationship Between Iron Oxides and Surface Charge Characteristics in Soils

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; WANGWEI-JUN

    1991-01-01

    The relationship between iron oxides and surface charge characteristics in variable charge soils (latosol and red earth) was studied in following three ways.(1)Remove free iron oxides (Fed) and amorphous iron oxides (Feo) from the soils with sodium dithionite and acid ammonium oxalate solution respectively.(2) Add 2% glucose (on the basis of air-dry soil weight) to soils and incubate under submerged condition to activate iron oxides,and then the mixtures are dehydrated and air-dried to age iron oxides.(3) Precipitate various crystalline forms of iron oxides onto kaolinite.The results showed that free iron oxides (Fed) were the chief carrier of variable positive charges.Of which crystalline iron oxides (Fed-Feo) presented mainly as discrete particles in the soils and could only play a role of the carrier of positive charges,and did little influence on negative charges.Whereas the amorphous iron oxides (Feo),which presented mainly fas a coating with a large specific surface area,not only had positive charges,but also blocked the negative charge sites in soils.Submerged incubation activated iron oxides in the soils,and increased the amount of amorphous iron oxides and the degree of activation of iron oxide,which resulted in the increase of positive and negative charges of soils.Dehydration and air-dry aged iron oxides in soils and decreased the amount of amorphous iron oxides and the degree of activation of iron oxide,and also led to the decrease of positive and negative charges.Both the submerged incubation and the dehydration and air-dry had no significant influence on net charges.Precipitation of iron oxides onto kaolinite markedly increased positive charges and decreased negative charges.Amorphous iron oxide having a larger surface area contributed more positive charge sites and blocked more negative charge sites in kaolinite than crystalline goethite.

  10. Interaction between alloying and hardening of cast iron surface

    Institute of Scientific and Technical Information of China (English)

    刘政军; 郝雪枫; 傅迎庆; 牟力军

    2002-01-01

    To improve wear resistance of surface will increase the service life of gray cast iron directly. This paper presents that gray cast iron surface coated with alloy powder is locally remelted by TIG arc to increase the wear resistance. The influences of arc current and scanning rate etc on surface properties are found. Under different conditions, the microstructure, hardness and wear resistance of remelted layer are analyzed and measured. The results indicate that the gray cast iron surface can be strengthened by TIG arc local remelting treatment. Especially, surface alloying hardening effect is best and surface properties are improved remarkably.

  11. Possible surface nematic order in iron pnictides

    Science.gov (United States)

    Song, Kok Wee; Koshelev, Alexei

    Nematic fluctuations play important role in the physics of the iron-based superconductors. Indications for weak precursor nematic transition has been found in the compound BaAs2-xPxFe2 [1 ]. However, high-resolution specific-heat measurements did not reveal any bulk transition [2 ]. To resolve this controversy, we consider the possibility of the surface nematic transition preceding the bulk transition. We consider the simplest model of two interacting quasi-two-dimensional electronic bands and explore the free-surface effects on the nematic order. We found that three-dimensional effects suppress the bulk nematic order and therefore this order is enhanced near the surface. [1 ]Kasahara, S., et al. ''Electronic nematicity above the structural and superconducting transition in Ba(As1-xPxFe)2.'' Nature 486.7403 (2012): 382-385. [2 ]Luo, X., et al. ''Antiferromagnetic and nematic phase transitions in Ba(As1-xPxFe)2 studied by ac microcalorimetry and SQUID magnetometry.'' Physical Review B 91.9 (2015): 094512. This work was supported by the Center for Emergent Superconductivity, an Energy FrontierResearch Center funded by the US DOE, Office of Science, under Award No. DEAC0298CH1088.

  12. Laser surface treatment of grey cast iron for automotive applications

    NARCIS (Netherlands)

    Ocelik, V.; Tang, P.N.; de Boer, M.C.; de Oliveira, U.; de Hosson, J.T.M.; DeHosson, JTM; Brebbia, CA; Nishida, SI

    2005-01-01

    The surface of pearlitic grey cast iron was treated using a 2 kW Nd:YAG laser beam with the final aim to improve its surface properties, mainly for automotive applications. Two kinds of laser surface treatments were experimentally applied. In the laser surface hardening approach the surface of cast

  13. Laser surface treatment of grey cast iron for automotive applications

    NARCIS (Netherlands)

    Ocelik, V.; Tang, P.N.; de Boer, M.C.; de Oliveira, U.; de Hosson, J.T.M.; DeHosson, JTM; Brebbia, CA; Nishida, SI

    2005-01-01

    The surface of pearlitic grey cast iron was treated using a 2 kW Nd:YAG laser beam with the final aim to improve its surface properties, mainly for automotive applications. Two kinds of laser surface treatments were experimentally applied. In the laser surface hardening approach the surface of cast

  14. Determining Iron Content in Foods by Spectrophotometry.

    Science.gov (United States)

    Adams, Paul E.

    1995-01-01

    Describes a laboratory experiment for secondary school chemistry students utilizing the classic reaction between the iron(III) ion and the thiocyanate ion. The experiment also works very well in other chemistry courses as an experience in spectrophotometric analysis. (PVD)

  15. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    Directory of Open Access Journals (Sweden)

    He Quanguo

    2008-01-01

    Full Text Available Abstract Surface functionalized magnetic iron oxide nanoparticles (NPs are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed.

  16. Microstructure evolution during surface alloying of ductile iron and austempered ductile iron by electron beam melting

    Science.gov (United States)

    Gulzar, A.; Akhter, J. I.; Ahmad, M.; Ali, G.; Mahmood, M.; Ajmal, M.

    2009-07-01

    Alloying and microstructural modification of surfaces by electron beam has become popular to tailor the surface properties of materials. Surface modification of as-received ductile iron, Ni-plated ductile iron and Ni-plated austempered ductile iron was carried out by electron beam melting to improve the surface properties. Martensitic structure evolved in the heat affected zone and ledeburite structure was produced in the molten zone of the ductile iron. Microhardness of the melted specimens enhanced considerably as compared to the as-received samples. However the microhardness of melted Ni-plated samples is lower than that of the unplated specimens. X-ray diffraction clearly revealed the formation of an austenite and Fe 3C phases in the electron beam molten zone. The broadening of peaks suggests refinement of the microstructure as well as internal stresses generated during electron beam melting.

  17. Microstructure evolution during surface alloying of ductile iron and austempered ductile iron by electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Gulzar, A. [Materials Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Akhter, J.I. [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Ahmad, M., E-mail: maqomer@yahoo.com [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Ali, G. [Physics Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad (Pakistan); Mahmood, M. [Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan); Ajmal, M. [Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore (Pakistan)

    2009-07-30

    Alloying and microstructural modification of surfaces by electron beam has become popular to tailor the surface properties of materials. Surface modification of as-received ductile iron, Ni-plated ductile iron and Ni-plated austempered ductile iron was carried out by electron beam melting to improve the surface properties. Martensitic structure evolved in the heat affected zone and ledeburite structure was produced in the molten zone of the ductile iron. Microhardness of the melted specimens enhanced considerably as compared to the as-received samples. However the microhardness of melted Ni-plated samples is lower than that of the unplated specimens. X-ray diffraction clearly revealed the formation of an austenite and Fe{sub 3}C phases in the electron beam molten zone. The broadening of peaks suggests refinement of the microstructure as well as internal stresses generated during electron beam melting.

  18. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    The interest in the role of ferrous iron in diabetes pathophysiology has been revived by recent evidence of iron as an important determinant of pancreatic islet inflammation and as a biomarker of diabetes risk and mortality. The iron metabolism in the β-cell is complex. Excess free iron is toxic......, but at the same time, iron is required for normal β-cell function and thereby glucose homeostasis. In the pathogenesis of diabetes, iron generates reactive oxygen species (ROS) by participating in the Fenton chemistry, which can induce oxidative damage and apoptosis. The aim of this review is to present...... and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...

  19. Proposal to determine the Fermi-surface topology of a doped iron-based superconductor using bulk-sensitive Fourier-transform Compton scattering

    NARCIS (Netherlands)

    Wang, Y.J.; Lin, H.; Barbiellini, B.; Mijnarends, P.E.; Kaprzyk, S.; Markiewicz, R.S.; Bansil, A.

    2010-01-01

    We have carried out first-principles calculations of the Compton scattering spectra to demonstrate that the filling of the hole Fermi surface in LaO1−xFxFeAs produces a distinct signature in the Fourier-transformed Compton spectrum when the momentum transfer vector lies along the [100] direction. We

  20. Thermal diffusion of potassium on the modified iron surface

    Energy Technology Data Exchange (ETDEWEB)

    Narkiewicz, U. [Institute of Chemical and Environment Engineering, Technical University of Szczecin, PuIaskiego 10, 70-322 Szczecin (Poland)]. E-mail: urszula.narkiewicz@ps.pl; Moszynski, D. [Institute of Chemical and Environment Engineering, Technical University of Szczecin, PuIaskiego 10, 70-322 Szczecin (Poland); BrosIawski, M. [Institute of Chemical and Environment Engineering, Technical University of Szczecin, PuIaskiego 10, 70-322 Szczecin (Poland)

    2005-10-31

    The diffusion of potassium on the polycrystalline iron surface modified by adsorbed oxygen and nitrogen has been studied by means of AES. The migration of potassium atoms has been observed independently on the constitution of the iron surface in the temperature range between 300 and 450 deg. C. The final concentration of potassium on the iron surface increases with temperature from 300 to 400 deg. C, irrespective of what atoms accompany potassium on the surface. At 450 deg. C, the final level of potassium concentration is decreased. The profiles of the concentration on the surface along the line crossing the source of potassium were also acquired. Applying the diffusion model of finite source, the diffusion coefficient of potassium for oxygen-covered and nitrogen-covered surfaces were evaluated.

  1. Determinants of compliance to iron supplementation among ...

    African Journals Online (AJOL)

    2014-01-28

    Jan 28, 2014 ... Nigerian Journal of Clinical Practice • Sep-Oct 2014 • Vol 17 • Issue 5 ... supplementation after adjusting for other factors in the binary logistic regression analysis (P < 0.05). .... Definition of compliance to iron supplementation.

  2. Changes Found on Run-In and Scuffed Surfaces of Steel Chrome Plate, and Cast Iron

    Science.gov (United States)

    Good, J. N.; Godfrey, Douglas

    1947-01-01

    A study was made of run-in and scuffed steel, chrome-plate, and cast-iron surfaces. X-ray and electron diffraction techniques, micro-hardness determinations, and microscopy were used. Surface changes varied and were found to include three classes: chemical reaction, hardening, and crystallite-size alteration. The principal chemical reactions were oxidation and carburization.

  3. Biobased coating for iron comprising surfaces

    NARCIS (Netherlands)

    Koenders, E.A.B.; Picken, S.J.

    2015-01-01

    The present invention is in the field of a composition for forming a bio-compatible membrane applicable to building material, such as steel, stainless steel, iron alloy, cast steel, etc., to a method of applying said composition for forming a bio-compatible membrane, a biocompatible membrane, use of

  4. Adsorbed water on iron surface by molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, F.W.; Campos, T.M.B.; Cividanes, L.S., E-mail: flaviano@ita.br; Simonetti, E.A.N.; Thim, G.P.

    2016-01-30

    Graphical abstract: - Highlights: • We developed a new force field to describe the Fe–H{sub 2}O interaction. • We developed a new force field to describe the flexible water model at low temperature. • We analyze the orientation of water along the iron surface. • We calculate the vibrational spectra of water near the iron surface. • We found a complex relationship between water orientation and the atomic vibrational spectra at different sites of adsorption along the iron surface. - Abstract: The adsorption of H{sub 2}O molecules on metal surfaces is important to understand the early process of water corrosion. This process can be described by computational simulation using molecular dynamics and Monte Carlo. However, this simulation demands an efficient description of the surface interactions between the water molecule and the metallic surface. In this study, an effective force field to describe the iron-water surface interactions was developed and it was used in a molecular dynamics simulation. The results showed a very good agreement between the simulated vibrational-DOS spectrum and the experimental vibrational spectrum of the iron–water interface. The water density profile revealed the presence of a water double layer in the metal interface. Furthermore, the horizontal mapping combined with the angular distribution of the molecular plane allowed the analysis of the water structure above the surface, which in turn agrees with the model of the double layer on metal surfaces.

  5. Iron Cycling at Corroding Carbon Steel Surfaces

    Science.gov (United States)

    2013-01-01

    Tian J. 1998. Manganite reduction by Shewanella putrefaciens mr-4. Am Mineral. 83:1564–1572. Larsen O, Postma D. 2001. Kinetics of reductive bulk...of the genus Shewanella ). Inhibitor and competition experiments suggest that Fe3+ is an efficient electron acceptor similar to nitrate in redox abil... Shewanella sp. and Lovley et al. (1987) working with Geobacter sp. demonstrated that solid manganese and iron oxides, respectively, could serve as electron

  6. SURFACE CAST IRON STRENGTHENING USING COMBINED LASER AND ULTRASONIC PROCESSING

    Directory of Open Access Journals (Sweden)

    O. Devojno

    2013-01-01

    Full Text Available The paper provides an analysis of ultrasonic surface plastic deformation and subsequent laser thermal strengthening of gray cast iron parts in the regime of hardening from a solid state with the purpose to obtain strengthened surface layers of bigger depth and less roughness of the processed surface. Program complex ANSYS 11.0 has been used for calculation of temperature fields induced by laser exposure.  The appropriate regime of laser processing without surface fusion has been selected on the basis of the applied complex. The possibility of displacement in the bottom boundary of α–γ-transformation temperature  for СЧ20 with 900 °С up to 800 °С is confirmed due to preliminary ultrasonic surface plastic deformation of the surface that allows to expand technological opportunities of laser quenching  of gray  cast iron from a solid state. 

  7. The surface layer of austempered ductile iron investment castings properties

    OpenAIRE

    D. Myszka; M. Kłębczyk; Zych, A.; L. Kwiatkowski

    2009-01-01

    The article presents a unique process of carbonnitriding and nitriding the precision casting surfaces of austempered ductile iron. The results of the research are pointing that adequate process parameters allow to obtain multiple increase of wear resistance and a significant increase of corrosion resistance. Also, changes of cast microstructure and hardness are presented.

  8. The surface layer of austempered ductile iron investment castings properties

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2009-01-01

    Full Text Available The article presents a unique process of carbonnitriding and nitriding the precision casting surfaces of austempered ductile iron. The results of the research are pointing that adequate process parameters allow to obtain multiple increase of wear resistance and a significant increase of corrosion resistance. Also, changes of cast microstructure and hardness are presented.

  9. Direct spectrophotometric determination of iron in non-ferrous alloys.

    Science.gov (United States)

    Nan, Z; Yuan-Xiang, G; Qing, G Y; Xu-Zhang, Y; Zhi-Ren, L

    1989-08-01

    Disodium 3-(2-pyridyl)-1,2,4-triazine-5,6-di(4'-phenylsulphonate) is used for determination of iron in metal analysis. High selectivity is achieved by using a ligand buffer and substoichiometric masking. Interference from 0.9 mg of Cu(II) can be completely eliminated by combined reduction and masking with ascorbic acid and thiosemicarbazide. Beer's law is obeyed over the range 0.4-1.6 mug/ml iron in the final solution, with a standard deviation of 0.02 mug/ml. The method has been successfully applied to determination of iron (without preseparation) in a number of non-ferrous metals and alloys, with a coefficient of variation of 1.2-5.0%.

  10. Surface protein IsdC and Sortase B are required for heme-iron scavenging of Bacillus anthracis.

    Science.gov (United States)

    Maresso, Anthony W; Chapa, Travis J; Schneewind, Olaf

    2006-12-01

    Bacillus anthracis, the spore-forming agent of anthrax, requires iron for growth and is capable of scavenging heme-iron during infection. We show here that the B. anthracis iron-regulated surface determinants (isd) locus encompasses isdC, specifying a heme-iron binding surface protein. Anchoring of IsdC to the cell wall envelopes of vegetative bacilli requires srtB, which encodes sortase B. Purified sortase B cleaves IsdC between the threonine and the glycine of its NPKTG motif sorting signal. B. anthracis variants lacking either isdC or srtB display defects in heme-iron scavenging, suggesting that IsdC binding to heme-iron in the cell wall envelope contributes to bacterial uptake of heme.

  11. Free surface damage induced by irradiation of BCC iron

    Science.gov (United States)

    Korchuganov, Aleksandr V.

    2016-11-01

    The influence of the crystallographic orientation of bcc iron samples on the character of structural changes near the free surface irradiated with ions was studied in the framework of a molecular dynamics method. Irradiation of the (111) surface leads to the formation of craters surrounded by atoms escaped on the surface (adatoms). In the case of the (110) surface irradiation, a vacancy-type dislocation loop with the Burgers vector a or a/2 was formed. The number of adatoms and survived point defects was greater in the sample with the (110) surface than in the sample with the (111) surface for the atomic displacement cascade energies lower than 20 keV. The influence of the irradiated surface orientation on the number of generated point defects decreased with the increasing atomic displacement cascade energy.

  12. X-ray lattice strain determination in surface layers

    DEFF Research Database (Denmark)

    Somers, Marcel A.J.; Pantleon, Karen

    2002-01-01

    The present article describes several aspects of lattice strain determination in surface layers by means of X-ray diffraction analysis. Several possibilities and the origins of stress in surface layers are illustrated by the following three cases: 200 nm thick Mo layers on glass substrates; 5.5 m.......5 microns thick TiN layers on heat treatable steel and 21 microns thick gamma prime-Fe4N1-x layers on iron....

  13. Cell surface characteristics enable encrustation-free survival of neutrophilic iron-oxidizing bacteria

    Science.gov (United States)

    Saini, G.; Chan, C. S.

    2011-12-01

    Microbial growth in mineralizing environments depends on the cells' ability to evade surface precipitation. Cell-mineral interactions may be required for metabolism, but if unmoderated, cells could become encrusted, which would limit diffusion of nutrients and waste across cell walls. A combination of cell surface charge and hydrophobicity could enable the survival of microbes in such environments by inhibiting mineral attachment. To investigate this mechanism, we characterized the surfaces of two neutrophilic iron-oxidizing bacteria (FeOB): Mariprofundus ferrooxydans, a Zetaproteobacterium from Fe(II)-rich submarine hydrothermal vents and a Betaproteobacterium Gallionellales strain R-1, recently isolated from a ferrous groundwater seep. Both bacteria produce iron oxyhydroxides, yet successfully escape surface encrustation while inhabiting milieu where iron minerals are also produced by abiotic processes. SEM-EDX and TEM-EELS analyses of cultured bacteria revealed no iron on the cell surfaces. Zeta potential measurements showed that these bacteria have very small negative surface charge (0 to -4 mV) over a pH range of 4-9, indicating near-neutrally charged surfaces. Water contact angle measurements and thermodynamic calculations demonstrate that both bacteria and abiotically-formed Fe oxhydroxides are hydrophilic. Extended-DLVO calculations showed that hydrophilic repulsion between cells and minerals dominates over electrostatic and Lifshitz-van der Waals interactions. This leads to overall repulsion between microbes and minerals, thus preventing surface encrustation. Low surface charge and hydrophilicity (determined by microbial adhesion to hydrocarbon assay) were common features for both live and azide-inhibited cells, which shows that surface characteristics do not depend on active metabolism. It is remarkable that these two phylogenetically-distant bacteria from different environments employ similar adaptations to prevent surface mineralization. Our results

  14. In-situ surface hardening of cast iron by surface layer metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Sebastian F., E-mail: s.fischer@gi.rwth-aachen.de [Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen (Germany); Muschna, Stefan, E-mail: smuschna@yahoo.de [Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen (Germany); Bührig-Polaczek, Andreas, E-mail: sekretariat@gi.rwth-aachen.de [Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen (Germany); Bünck, Matthias, E-mail: m.buenck@access-techcenter.de [Access e.V., Intzestraße 5, 52072 Aachen (Germany)

    2014-10-06

    Abrasive wear is a serious problem in many cast iron castings used in industry. To minimize failure and repair of these components, different strategies exist to improve their surface microhardness thus enhancing their wear resistance. However, most of these methods lead to very brittle and/or expensive castings. In the current work a new method for surface hardening is presented which utilizes surface layer metallurgy to generate in-situ a boron-enriched white cast iron surface layer with a high microhardness on a gray cast iron casting. To do this, sand molds are coated with a ferroboron suspension and cast with a cast iron melt. After solidification, a 100–900 µm thick layer of boron-enriched ledeburite is formed on the surface of the casting which produces an increase in the average microhardness from 284 HV{sub 0.1}±52 HV{sub 0.1} to 505 HV{sub 0.1}±87 HV{sub 0.1}. Analyses of the samples' core reveal a typical cast iron microstructure which leads to the conclusion that the coating mainly affects the castings' surface. By varying the grain size of the ferroboron powder in the coatings, it is shown that a powder size ≤100 µm is most suitable to create a boron-enriched ledeburite surface layer possessing high hardness values.

  15. Simultaneous Determination of Iron and Manganese in Water Using Artificial Neural Network Catalytic Spectrophotometric Method

    Institute of Scientific and Technical Information of China (English)

    JI Hongwei; XU Yan; LI Shuang; XIN Huizhen; CAO Hengxia

    2012-01-01

    A new analytical method using Back-Propagation(BP)artificial neural network and kinetic spectrophotometry for simultaneous determination of iron and magnesium in tap water,the Yellow River water and seawater is established.By conditional experiments,the optimum analytical conditions and parameters are obtained.Levenberg-Marquart(L-M)algorithm is used for calculation in BP neural network.The topological structure of three-layer BP ANN network architecture is chosen as 15-16-2(nodes).The initial value of gradient coefficientμ is fixed at 0.001 and the increase factor and reduction factor ofμ take the default values of the system.The data are processed by computers with our own programs written in MATLAB 7.0.The relative standard deviation of the calculated results for iron and manganese is 2.30% and 2.67% respectively.The results of standard addition method show that for the tap water,the recoveries of iron and manganese are in the ranges of 98.0%-104.3% and 96.5%-104.5%,and the RSD is in the range of 0.23%-0.98%;for the Yellow River water(Lijin district of Shandong Province),the recoveries of iron and manganese are in the ranges of 96.0%-101.0% and 98.7%-104.2%,and the RSD is in the range of 0.13%-2.52%;for the seawater in Qingdao offshore,the recoveries of iron and manganese are in the ranges of 95.3%-104.8% and 95.3%-104.7%,and the RSD is in the range of 0.14%-2.66%.It is found that 21 common cations and anions do not interfere with the determination of iron and manganese under the optimum experimental conditions.This method exhibits good reproducibility and high accuracy in the determination of iron and manganese and can be used for the simultaneous determination of iron and manganese in tap water and natural water.By using the established ANN-catalytic spectrophotometric method,the iron and manganese concentrations of the surface seawater at 11 sites in Qingdao offshore are determined and the level distribution maps of

  16. Microstructure and hardness of WC-Co particle reinforced iron matrix surface composite

    OpenAIRE

    Zhang Peng; Zeng Shaolian; Zhang Zhiguo

    2013-01-01

    In this study, a high Cr cast iron surface composite material reinforced with WC-Co particles 2-6 mm in size was prepared using a pressureless sand mold infiltration casting technique. The composition, microstructure and hardness were determined by means of energy dispersive spectrometry (EDS), electron probe microanalysis (EPMA), scanning electron microscope (SEM) and Rockwell hardness measurements. It is determined that the obtained composite layer is about 15 mm thick with a WC-Co particle...

  17. Designing porous metallic glass compact enclosed with surface iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jae Young; Park, Hae Jin; Hong, Sung Hwan; Kim, Jeong Tae; Kim, Young Seok; Park, Jun-Young; Lee, Naesung [Hybrid Materials Center (HMC), Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Seo, Yongho [Graphene Research Institute (GRI) & HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Park, Jin Man, E-mail: jinman_park@hotmail.com [Global Technology Center, Samsung Electronics Co., Ltd, 129 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-742 (Korea, Republic of); Kim, Ki Buem, E-mail: kbkim@sejong.ac.kr [Hybrid Materials Center (HMC), Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2015-06-25

    Highlights: • Porous metallic glass compact was developed using electro-discharge sintering process. • Uniform PMGC can only be achieved when low electrical input energy was applied. • Functional iron-oxides were formed on the surface of PMGCs by hydrothermal technique. - Abstract: Porous metallic glass compact (PMGC) using electro-discharge sintering (EDS) process of gas atomized Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} metallic glass powder was developed. The formation of uniform PMGC can only be achieved when low electrical input energy was applied. Functional iron-oxides were formed on the surface of PMGCs by hydrothermal technique. This finding suggests that PMGC can be applied in the new area such as catalyst via hydrothermal technique and offer a promising guideline for using the metallic glasses as a potential functional application.

  18. Colorimetry and constant-potential coulometry determinations of transferrin-bound iron, total iron-binding capacity, and total iron in serum containing iron-dextran, with use of sodium dithionite and alumina columns.

    Science.gov (United States)

    Jacobs, J C; Alexander, N M

    1990-10-01

    After the parenteral administration of iron-dextran (imferon), the increased total iron concentrations in serum can be determined by atomic absorption spectroscopy and by colorimetric methods involving sodium dithionite, which reductively dissociates iron from the dextran complex. We report that constant-potential coulometry detects only about 55-70% of dextran-bound iron before dithionite reduction and variable amounts after reaction with the reducing agent. In addition, we have developed a procedure for determining transferrin-bound iron, total iron-binding capacity (TIBC), total iron, and dextran-bound iron with the Kodak Ektachem colorimetric system. In determining total serum iron, the sample is first mixed with sodium dithionite, which rapidly dissociates all dextran-bound iron, but does not remove iron from either transferrin or hemoglobin. After the mixture is applied to an Ektachem slide, transferrin-bound iron is released at pH 4 and is detected together with the iron previously bound to dextran. TIBC is determined by mixing serum with ferric citrate in moderate excess and filtering through a small alumina (Al2O3) column, which binds excess free iron and iron-dextran; the iron in the column eluate represents the TIBC. Transferrin-bound iron is determined by applying diluted serum without added ferric citrate to an alumina column and measuring the iron in the column eluate. Dextran-bound iron is equivalent to the difference between total and transferrin-bound iron. Using this method, we found that transferrin iron-binding sites are saturated in vitro by excess iron-dextran less efficiently than by ferric citrate.

  19. Experimental Research on the Determination of the Coefficient of Sliding Wear under Iron Ore Handling Conditions

    Directory of Open Access Journals (Sweden)

    G. Chen

    2017-09-01

    Full Text Available The handling of iron ore bulk solids maintains an increasing trend due to economic development. Because iron ore particles have hard composites and irregular shapes, the bulk solids handling equipment surface can suffer from severe sliding wear. Prediction of equipment surface wear volume is beneficial to the efficient maintenance of worn areas. Archard’s equation provides a theoretical solution to predict wear volume. To use Archard’s equation, the coefficient of sliding wear must be determined. To our best knowledge, the coefficient of sliding wear for iron ore handling conditions has not yet been determined. In this research, using a pin-on-disk tribometer, the coefficients of sliding wear for both Sishen particles and mild steel are determined with regard to iron ore handling conditions. Both naturally irregular and spherical shapes of particles are used to estimate average values of wear rate. Moreover, the hardness and inner structures of Sishen particles are examined, which adds the evidence of the interpretation of wear results. It is concluded that the coefficients of sliding wear can vary largely for both Sishen particle and mild steel. The wear rate decreases from transient- to steady-state. The average coefficient of sliding wear is capable of predicting wear with respect to long distances at the steady-state. Two types of sliding friction are distinguished. In addition, it is found that the temperature rise of the friction pairs has negligible influence on wear rate.

  20. Microstructure and properties of cast iron after laser surface hardening

    Directory of Open Access Journals (Sweden)

    Stanislav

    2013-12-01

    Full Text Available Laser surface hardening of cast iron is not trivial due to the material’s heterogeneity and coarse-grained microstructure, particularly in massive castings. Despite that, hardening of heavy moulds for automotive industry is in high demand. The present paper summarises the findings collected over several years of study of materials structure and surface properties. Phase transformations in the vicinity of graphite are described using examples from production of body parts in automotive industry. The description relates to formation of martensite and carbide-based phases, which leads to hardness values above 65 HRC and to excellent abrasion resistance.

  1. Development of a method for determination of metallic iron content within hot briquette iron (HBI for steelmaking

    Directory of Open Access Journals (Sweden)

    Morcali M.H.

    2016-01-01

    Full Text Available The growing use of metallic iron in metallurgy and industrial chemical applications requires a fast, easy and cheap method for the determination of metallic iron, not merely in recyclable materials, such as iron pellets, reduced iron mill scale dust, electric arc furnace dust and pig iron, but from hot briquette iron (HBI as well. This study investigates a new method for determination of metallic iron within HBI used for steel-making materials. The effects of reaction time, temperature, and stirring rate were studied. The concentration of iron was determined via Atomic Absorption Spectroscopy (AAS. After the optimization study, high-purity metallic iron powder (Sigma-Aldrich, PubChem Substance ID 24855469 was used to compare efficiencies and identify the optimum conditions; The present study was matched with international standard methods (BS ISO 5416:2006, IS 15774:2007. Results were consistent with certified values and metallic iron content could be determined within the 95% confidence level. The purposed method is easy, straightforward, and cheap.

  2. Determination of retinal surface area.

    Science.gov (United States)

    Nagra, Manbir; Gilmartin, Bernard; Thai, Ngoc Jade; Logan, Nicola S

    2017-09-01

    Previous attempts at determining retinal surface area and surface area of the whole eye have been based upon mathematical calculations derived from retinal photographs, schematic eyes and retinal biopsies of donor eyes. 3-dimensional (3-D) ocular magnetic resonance imaging (MRI) allows a more direct measurement, it can be used to image the eye in vivo, and there is no risk of tissue shrinkage. The primary purpose of this study is to compare, using T2-weighted 3D MRI, retinal surface areas for superior-temporal (ST), inferior-temporal (IT), superior-nasal (SN) and inferior-nasal (IN) retinal quadrants. An ancillary aim is to examine whether inter-quadrant variations in area are concordant with reported inter-quadrant patterns of susceptibility to retinal breaks associated with posterior vitreous detachment (PVD). Seventy-three adult participants presenting without retinal pathology (mean age 26.25 ± 6.06 years) were scanned using a Siemens 3-Tesla MRI scanner to provide T2-weighted MR images that demarcate fluid-filled internal structures for the whole eye and provide high-contrast delineation of the vitreous-retina interface. Integrated MRI software generated total internal ocular surface area (TSA). The second nodal point was used to demarcate the origin of the peripheral retina in order to calculate total retinal surface area (RSA) and quadrant retinal surface areas (QRSA) for ST, IT, SN, and IN quadrants. Mean spherical error (MSE) was -2.50 ± 4.03D and mean axial length (AL) 24.51 ± 1.57 mm. Mean TSA and RSA for the RE were 2058 ± 189 and 1363 ± 160 mm(2) , respectively. Repeated measures anova for QRSA data indicated a significant difference within-quadrants (P area/mm increase in AL. Although the differences between QRSAs are relatively small, there was evidence of concordance with reported inter-quadrant patterns of susceptibility to retinal breaks associated with PVD. The data allow AL to be converted to QRSAs, which will assist further

  3. Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

    Science.gov (United States)

    Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira; Qin, Ying; Bao, Yuping

    2017-04-01

    We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

  4. Determination of ferrous and ferric iron in aqueous biological solutions

    Energy Technology Data Exchange (ETDEWEB)

    Pepper, S.E. [Earth and Environmental Sciences Division, Los Alamos National Laboratory, 1400 University Drive, Carlsbad, NM 88220 (United States); Borkowski, M., E-mail: marian@lanl.gov [Earth and Environmental Sciences Division, Los Alamos National Laboratory, 1400 University Drive, Carlsbad, NM 88220 (United States); Richmann, M.K.; Reed, D.T. [Earth and Environmental Sciences Division, Los Alamos National Laboratory, 1400 University Drive, Carlsbad, NM 88220 (United States)

    2010-03-24

    A solvent extraction method was employed to determine ferrous and ferric iron in aqueous samples. Fe{sup 3+} is selectively extracted into the organic phase (n-heptane) using HDEHP (bis(2-ethylhexyl) hydrogen phosphate) and is then stripped using a strong acid. After separation, both oxidation states and the total iron content were determined directly by ICP-MS analysis. This extraction method was refined to allow determination of both iron oxidation states in the presence of strong complexing ligands, such as citrate, NTA and EDTA. The accuracy of the method was verified by crosschecking using a refinement of the ferrozine assay. Presented results demonstrate the ability of the extraction method to work in a microbiological system in the presence of strong chelating agents following the bioreduction of Fe{sup 3+} by the Shewanella alga BrY. Based on the results we report, a robust approach was defined to separately analyze Fe{sup 3+} and Fe{sup 2+} under a wide range of potential scenarios in subsurface environments where radionuclide/metal contamination may coexist with strongly complexing organic contaminants.

  5. SURFACE-MODIFICATION OF FINE RED IRON OXIDE PIGMENT

    Institute of Scientific and Technical Information of China (English)

    Shuilin Zheng; Qinghui Zhang

    2003-01-01

    Surface-modification of fine red iron oxide pigment was carried out in an aqueous solution of sodium polyacrylate. The sedimentation time of modified samples in water increased from 1.05 to 264.4 hours while the particle size (d50) decreased from 1.09 to 0.85 μm, and the tinting strength increased from 100 to 115. The surface-modification as well as the dispersing and stabilizing mechanisms in aqueous solution of the samples were studied by means of IR,Thermal analysis and Zeta potential. The results showed that the modifier molecules acted on the surface of the particles by chemical and physical adsorption, and after the particles were dispersed in aqueous solution, endowing the particle surface with a relatively high negative Zeta potential, thus enhancing electrostatic and steric repulsion between particles for their effective stabilization.

  6. Fob1 and Fob2 Proteins Are Virulence Determinants of Rhizopus oryzae via Facilitating Iron Uptake from Ferrioxamine.

    Science.gov (United States)

    Liu, Mingfu; Lin, Lin; Gebremariam, Teclegiorgis; Luo, Guanpingsheng; Skory, Christopher D; French, Samuel W; Chou, Tsui-Fen; Edwards, John E; Ibrahim, Ashraf S

    2015-05-01

    Dialysis patients with chronic renal failure receiving deferoxamine for treating iron overload are uniquely predisposed for mucormycosis, which is most often caused by Rhizopus oryzae. Although the deferoxamine siderophore is not secreted by Mucorales, previous studies established that Rhizopus species utilize iron from ferrioxamine (iron-rich form of deferoxamine). Here we determined that the CBS domain proteins of Fob1 and Fob2 act as receptors on the cell surface of R. oryzae during iron uptake from ferrioxamine. Fob1 and Fob2 cell surface expression was induced in the presence of ferrioxamine and bound radiolabeled ferrioxamine. A R. oryzae strain with targeted reduced Fob1/Fob2 expression was impaired for iron uptake, germinating, and growing on medium with ferrioxamine as the sole source of iron. This strain also exhibited reduced virulence in a deferoxamine-treated, but not the diabetic ketoacidotic (DKA), mouse model of mucormycosis. The mechanism by which R. oryzae obtains iron from ferrioxamine involves the reductase/permease uptake system since the growth on ferrioxamine supplemented medium is associated with elevated reductase activity and the use of the ferrous chelator bathophenanthroline disulfonate abrogates iron uptake and growth on medium supplemented with ferrioxamine as a sole source of iron. Finally, R. oryzae mutants with reduced copies of the high affinity iron permease (FTR1) or with decreased FTR1 expression had an impaired iron uptake from ferrioxamine in vitro and reduced virulence in the deferoxamine-treated mouse model of mucormycosis. These two receptors appear to be conserved in Mucorales, and can be the subject of future novel therapy to maintain the use of deferoxamine for treating iron-overload.

  7. Construction of super-hydrophobic iron with a hierarchical surface structure

    Science.gov (United States)

    Yuan, Zhiqing; Bin, Jiping; Wang, Xian; Wang, Menglei; Peng, Chaoyi; Xing, Suli; Xiao, Jiayu; Zeng, Jingcheng; Xiao, Ximei; Fu, Xin

    2014-04-01

    Wettability of an iron surface is crucial for the wide applications of iron in practice. In this work, a hierarchical structure highly similar to that of the underside of a bamboo leaf was constructed on an iron surface via the template method and controllable etching. After modification by stearic acid, the iron surface with hierarchical structure showed excellent water repellency, with an average contact angle of 156° and a sliding angle of 3°. X-ray diffraction (XRD) techniques and Fourier transform infrared spectroscopy (FTIR) are applied to examine the chemical components of an iron surface.

  8. Surface Graphite Degeneration in Ductile Iron Castings for Resin Molds

    Institute of Scientific and Technical Information of China (English)

    Iulian Riposan; Mihai Chisamera; Stelian Stan; Torbjorn Skaland

    2008-01-01

    The objective of this paper is to review the factors influencing the formation of degenerated graph-ite layers on the surfaces of ductile iron castings for chemical rosins-acid molding and coro-making systems and how to reduce this defect. In the rosin mold technique the sulphur in the P-toluol sulphonic acid (PTSA),usually used as the hardener, has been identified as one factor causing graphite degeneration at the metal-mold interface. Less than 0.15% S in the mold (or even less than 0.07% S) can reduce the surface layer depth. Oxygen may also have an effect, especially for sulphur containing systems with turbulent flows in the mold, water-bearing no-bake binder systems, Mg-Silica reactions, or dross formation conditions. Despite the lower level of nitrogen in the iron melt after magnesium treatment (less than 90 ppm), nitrogen bearing res-ins have a profound effect on the frequency and severity of surface pinholes, but a limited influence on sur-face graphite degeneration.

  9. Studies of Self-assembled Monolayers Formed by Imidazoline on Iron Surface by SEM and SECM

    Institute of Scientific and Technical Information of China (English)

    Xiu Yu LIU; Shen Hao CHEN; Shuai MIAO; Su Xiang WU; Li Xia SHEN; Yuan Xing CAI; Hong Yan ZHAI

    2006-01-01

    The self-assembled monolayers (SAMs) of imidazoline (IM) on the iron surface were characterized by scanning electron microscope (SEM) and scanning electrochemical microscopy(SECM). The results showed that SAMs were an effective inhibition film for iron.

  10. ZIP8 is an iron and zinc transporter whose cell-surface expression is up-regulated by cellular iron loading.

    Science.gov (United States)

    Wang, Chia-Yu; Jenkitkasemwong, Supak; Duarte, Stephanie; Sparkman, Brian K; Shawki, Ali; Mackenzie, Bryan; Knutson, Mitchell D

    2012-10-05

    ZIP8 (SLC39A8) belongs to the ZIP family of metal-ion transporters. Among the ZIP proteins, ZIP8 is most closely related to ZIP14, which can transport iron, zinc, manganese, and cadmium. Here we investigated the iron transport ability of ZIP8, its subcellular localization, pH dependence, and regulation by iron. Transfection of HEK 293T cells with ZIP8 cDNA enhanced the uptake of (59)Fe and (65)Zn by 200 and 40%, respectively, compared with controls. Excess iron inhibited the uptake of zinc and vice versa. In RNA-injected Xenopus oocytes, ZIP8-mediated (55)Fe(2+) transport was saturable (K(0.5) of ∼0.7 μm) and inhibited by zinc. ZIP8 also mediated the uptake of (109)Cd(2+), (57)Co(2+), (65)Zn(2+) > (54)Mn(2+), but not (64)Cu (I or II). By using immunofluorescence analysis, we found that ZIP8 expressed in HEK 293T cells localized to the plasma membrane and partially in early endosomes. Iron loading increased total and cell-surface levels of ZIP8 in H4IIE rat hepatoma cells. We also determined by using site-directed mutagenesis that asparagine residues 40, 88, and 96 of rat ZIP8 are glycosylated and that N-glycosylation is not required for iron or zinc transport. Analysis of 20 different human tissues revealed abundant ZIP8 expression in lung and placenta and showed that its expression profile differs markedly from ZIP14, suggesting nonredundant functions. Suppression of endogenous ZIP8 expression in BeWo cells, a placental cell line, reduced iron uptake by ∼40%, suggesting that ZIP8 participates in placental iron transport. Collectively, these data identify ZIP8 as an iron transport protein that may function in iron metabolism.

  11. Cohesive Relations for Surface Atoms in the Iron-Technetium Binary System

    Directory of Open Access Journals (Sweden)

    Christopher D. Taylor

    2011-01-01

    Full Text Available Iron-technetium alloys are of relevance to the development of waste forms for disposition of radioactive technetium-99 obtained from spent nuclear fuel. Corrosion of candidate waste forms is a function of the local cohesive energy (loc of surface atoms. A theoretical model for calculating loc is developed. Density functional theory was used to construct a modified embedded atom (MEAM potential for iron-technetium. Materials properties determined for the iron-technetium system were in good agreement with the literature. To explore the relationship between local structure and corrosion, MEAM simulations were performed on representative iron-technetium alloys and intermetallics. Technetium-rich phases have lower loc, suggesting that these phases will be more noble than iron-rich ones. Quantitative estimates of loc based on numbers of nearest neighbors alone can lead to errors up to 0.5 eV. Consequently, atomistic corrosion simulations for alloy systems should utilize physics-based models that consider not only neighbor counts, but also local compositions and atomic arrangements.

  12. Surface ocean iron fertilization: The role of airborne volcanic ash and iron-flux into the Pacific Ocean

    Science.gov (United States)

    Olgun, N.; Duggen, S.; Croot, P.; Dietze, H.

    2009-04-01

    Iron is a limiting micro-nutrient for marine primary production (MPP) in vast areas in the surface ocean. Hence, atmospheric supply of iron to the surface ocean can affect marine biogeochemical cycles, associated ocean-atmosphere exchange of CO2 and eventually climate development. Airborne volcanic ash from volcanic eruptions can be an important atmospheric iron-source in the surface ocean by releasing bio-available iron while settling through in the surface ocean. Here we present new data from time-dependent geochemical experiments with pristine (unhydrated) volcanic ash samples and natural seawater by means of Cathodic Stripping Voltammetry. Our results demonstrate that volcanic ash mobilizes significant amounts of soluble Fe within 60 minutes of contact with natural seawater. Depending on the amount of volcanic ash deposited offshore during major volcanic eruptions and the amount of iron that ash can release on contact with seawater, the calculated increase in the surface ocean Fe levels range from several nanomolar up to several hundred nanomolar (nM). Only 2 nM increase in iron concentrations can stimulate massive diatom blooms in the oceanic regions in which MPP is limited by the availability of iron (the iron-limited oceanic areas) (Wells, 2003). Therefore volcanic ash should be able to significantly affect marine phytoplankton growth in an ash fall area, acting as an iron fertilizer. Based on our new iron-release data and marine sediment core data we provide the first estimate of the flux of Fe from volcanic ash into the Pacific Ocean that covers more than 60 percent of the iron-limited oceanic regions. Our calculations show that the flux of Fe from volcanic ash is comparable to the order of magnitude of the flux of Fe from aeolian dust. Our study shows that volcanic ash is a major and so far underestimated atmospheric iron-source for the oceans and therefore an important component in marine biogeochemical iron cycles. Wells, M.L.: The level of iron

  13. Influence of surface topography on the surface durability of steam oxidised sintered iron

    Directory of Open Access Journals (Sweden)

    José Daniel Biasoli de Mello

    2005-06-01

    Full Text Available Durability of surfaces has been reported as the main factor affecting tribological behavior of steam oxidised sintered iron. The presence of surface pores and their negative influence on load bearing capacity, suggest that surface topography might play an important role on the durability of the oxide layer. In this paper, the influence of compaction pressure and powder grade on surface topography, and as a consequence, its effect on the tribological behavior of steam oxidised sintered iron has been analysed. Specimens prepared from atomised iron powders with different sizes were compacted using 4 different pressures, sintered, and then subjected to steam treatment. Tribological characterisation was carried out in a reciprocating sliding wear test. Although the processing parameters affected the surface topography to a considerable extent, the main influence may be attributed to powder grade. A strong influence of surface topography on the durability distance, evaluated in terms of the evolution of contact resistance with total sliding distance, has been highlighted. Surfaces which were smoother and had high load-carrying capacity were always associated with a higher durability distance.

  14. Plasma sintering of unalloyed iron: a study of surface porosity

    Directory of Open Access Journals (Sweden)

    Lourenço Jorge Magner

    2004-01-01

    Full Text Available Samples of unalloyed iron powder were compacted and sintered in an abnormal glow discharge, generated in a gas mixture of 80% Ar + 20% H2 by using a pulsed power source. The samples were placed on a holder, acting as the discharge cathode, and were heated by the bombardment of ions, strongly accelerated in the cathode sheath. Sintering was performed at temperatures of 1173, 1273 and 1373 K for 30 min, varying the voltage applied to the cathode from 400 to 700 V and pressure ranging from 470 to 2650 Pa. It is shown that the kinetic energy of ions striking the sample surface increased approximately three times, when the voltage changed from 400 to 700 V, with a corresponding reduction of surface porosity. The surface sealing is related to the ion bombardment, which produced a high mobility of surface atoms and consequent enhanced diffusion as well as sputtering and condensation on the concave surface, resulting in an activation of surface sintering.

  15. Sol–gel method as a way of carbonyl iron powder surface modification for interaction improvement

    Energy Technology Data Exchange (ETDEWEB)

    Małecki, P., E-mail: pawel.malecki@pwr.edu.pl [Polymer Engineering and Technology Division, W-3, Wrocław University of Technology, Smoluchowskiego 25, 50 370 Wrocław (Poland); Kolman, K.; Pigłowski, J. [Polymer Engineering and Technology Division, W-3, Wrocław University of Technology, Smoluchowskiego 25, 50 370 Wrocław (Poland); Kaleta, J. [Department of Mechanics, Materials Science and Engineering, W-10, Wrocław University of Technology, Smoluchowskiego 25, 50-370 Wrocław (Poland); Krzak, J., E-mail: justyna.krzak@pwr.edu.pl [Department of Mechanics, Materials Science and Engineering, W-10, Wrocław University of Technology, Smoluchowskiego 25, 50-370 Wrocław (Poland)

    2015-03-15

    This article presents a method for modification of carbonyl iron particles’ surface (CIP), (d{sub 50}=4–9 µm) by silica coatings obtained using the sol–gel method. Reaction parameters were determined to obtain dry magnetic powder with homogeneous silica coatings without further processing and without any by-product in the solid or liquid phase. This approach is new among the commonly used methods of silica coating of iron particles. No attempt has been made to cover a carbonyl iron surface by silica in a waste-free method, up to date. In the current work two different silica core/shell structures were made by the sol–gel process, based on different silica precursors: tetraethoxy-silane (TEOS) and tetramethoxy-silane (TMOS). The dependence between the synthesis procedure and thickness of silica shell covering carbonyl iron particles has been described. Surface morphology of the modified magnetic particles and the coating thickness were characterized with the use of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Determination of the physicochemical structure of the obtained materials was performed by the energy-dispersive X-ray spectroscope (EDS), and the infrared technique (IR). The surface composition was analyzed using X-ray photoelectron spectroscopy (XPS). Additionally, distribution of particle size was measured using light microscopy. The new, efficient process of covering micro-size CIP with a nanometric silica layer was shown. Results of a performed analysis confirm the effectiveness of the presented method. - Highlights: • Proper covering CIP by sol–gel silica layer avoids agglomeration. • A new solid waste-free method of CIP coating is proposed. • Examination of the properties of modified CIP in depends on washing process. • Coatings on CIP particles doesn’t change the magnetic properties of particles.

  16. Theoretical Investigation of Hydrogen Adsorption and Dissociation on Iron and Iron Carbide Surfaces Using the ReaxFF Reactive Force Field Method

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Chenyu; van Duin, Adri C.T.; Sorescu, Dan C.

    2012-06-01

    We have developed a ReaxFF reactive force field to describe hydrogen adsorption and dissociation on iron and iron carbide surfaces relevant for simulation of Fischer–Tropsch (FT) synthesis on iron catalysts. This force field enables large system (>>1000 atoms) simulations of hydrogen related reactions with iron. The ReaxFF force field parameters are trained against a substantial amount of structural and energetic data including the equations of state and heats of formation of iron and iron carbide related materials, as well as hydrogen interaction with iron surfaces and different phases of bulk iron. We have validated the accuracy and applicability of ReaxFF force field by carrying out molecular dynamics simulations of hydrogen adsorption, dissociation and recombination on iron and iron carbide surfaces. The barriers and reaction energies for molecular dissociation on these two types of surfaces have been compared and the effect of subsurface carbon on hydrogen interaction with iron surface is evaluated. We found that existence of carbon atoms at subsurface iron sites tends to increase the hydrogen dissociation energy barrier on the surface, and also makes the corresponding hydrogen dissociative state relatively more stable compared to that on bare iron. These properties of iron carbide will affect the dissociation rate of H{sub 2} and will retain more surface hydride species, thus influencing the dynamics of the FT synthesis process.

  17. DETERMINATION OF RADIATOR COOLING SURFACE

    Directory of Open Access Journals (Sweden)

    A. I. Yakubovich

    2009-01-01

    Full Text Available The paper proposes a methodology for calculation of a radiator cooling surface with due account of heat transfer non-uniformity on depth of its core. Calculation of radiator cooling surfaces of «Belarus-1221» and «Belarus-3022» tractors has been carried out in the paper. The paper also advances standard size series of radiators for powerful «Belarus» tractor type.

  18. Liver iron content determination by magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    Konstantinos; Tziomalos; Vassilios; Perifanis

    2010-01-01

    Accurate evaluation of iron overload is necessary to establish the diagnosis of hemochromatosis and guide chelation treatment in transfusion-dependent anemia. The liver is the primary site for iron storage in patients with hemochromatosis or transfusion-dependent anemia, therefore, liver iron concentration (LIC) accurately re? ects total body iron stores. In the past 20 years, magnetic resonance imaging (MRI) has emerged as a promising method for measuring LIC in a variety of diseases. We review the potenti...

  19. New surface radiolabeling schemes of super paramagnetic iron oxide nanoparticles (SPIONs) for biodistribution studies

    Science.gov (United States)

    Nallathamby, Prakash D.; Mortensen, Ninell P.; Palko, Heather A.; Malfatti, Mike; Smith, Catherine; Sonnett, James; Doktycz, Mitchel J.; Gu, Baohua; Roeder, Ryan K.; Wang, Wei; Retterer, Scott T.

    2015-04-01

    Nanomaterial based drug delivery systems allow for the independent tuning of the surface chemical and physical properties that affect their biodistribution in vivo and the therapeutic payloads that they are intended to deliver. Additionally, the added therapeutic and diagnostic value of their inherent material properties often provides extra functionality. Iron based nanomaterials with their magnetic properties and easily tailorable surface chemistry are of particular interest as model systems. In this study the core radius of the iron oxide nanoparticles (NPs) was 14.08 +/- 3.92 nm while the hydrodynamic radius of the NPs, as determined by Dynamic Light Scattering (DLS), was between 90-110 nm. In this study, different approaches were explored to create radiolabeled NPs that are stable in solution. The NPs were functionalized with polycarboxylate or polyamine surface functional groups. Polycarboxylate functionalized NPs had a zeta potential of -35 mV and polyamine functionalized NPs had a zeta potential of +40 mV. The polycarboxylate functionalized NPs were chosen for in vivo biodistribution studies and hence were radiolabeled with 14C, with a final activity of 0.097 nCi mg-1 of NPs. In chronic studies, the biodistribution profile is tracked using low level radiolabeled proxies of the nanoparticles of interest. Conventionally, these radiolabeled proxies are chemically similar but not chemically identical to the non-radiolabeled NPs of interest. This study is novel as different approaches were explored to create radiolabeled NPs that are stable, possess a hydrodynamic radius of S1) High-Resolution Transmission Electron Microscopy (HRTEM) image of iron oxide nanoparticles, (S2) Superconducting Quantum Interference Device (SQUID) measurement of magnetization of super paramagnetic iron oxide nanoparticles, (S3) Fourier Transform Infrared Spectroscopy (FT-IR) spectra of Fe-Si-COO- synthesised using Grignard reagents (S4) FT-IR spectra of iron oxide nanoparticles

  20. Iron

    Science.gov (United States)

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  1. Iron

    Science.gov (United States)

    ... of iron stored in the body become low, iron deficiency anemia sets in. Red blood cells become smaller and ... from the lungs throughout the body. Symptoms of iron deficiency anemia include tiredness and lack of energy, GI upset, ...

  2. Microstructure and Magnetic Domains of Iron Films on Liquid Surfaces

    Institute of Scientific and Technical Information of China (English)

    XIE Jian-Ping; XIA A-Gen; ZHANG Chu-Hang; YANG Bo; FANG Zheng-Nong; YE Gao-Xiang

    2009-01-01

    Iron (Fe) films with a thickness ranging from 1.0 nm to 80.0 nm are deposited on silicone oil surfaces by a vapor phase deposition method. The films with a thickness of d < 2.0 nm do not exhibit planar morphology but ramified aggregates instead. Magnetic force microscopy studies for the Fe films (10.0nm≤d≤80.0nm) show that the domain wall structure is widespread and irregularly shaped and the oscillation phase shift Δθ, which records as the magnetic force image, changes from 0.29°to 0.81°. Correspondingly, the magnetic force gradient varies from 1.4×10~(-3) to 4.0×10~(-3)N/m, respectively. In our measurement, the characteristic domain walls, such as Bloch walls, Neel walls and cross-tie walls, are not observed in the film system clearly.

  3. Microstructural and Hardness Study of Pulsed Nd:YAG Laser Surface Alloyed Aluminum with Iron

    Science.gov (United States)

    Ansari, Mohammad; Soltani, Reza; Heydarzadeh Sohi, Mahmoud; Valefi, Zia

    2016-04-01

    In the present study, the feasibility of the formation of surface layers containing hard iron aluminides on AA6061-T6 aluminum via pre-plasma spraying with iron and subsequently double surface melting by pulsed Nd:YAG laser is studied. The effects of single and double laser surface melting on microstructure, phase formation, and hardness of the treated layers are examined. Single-step laser treatment resulted in the presence of undissolved iron particles surrounded by lump-like Al5Fe2 and needle-like Al3Fe intermetallic compounds. Double laser surface melting dissolved the retained undissolved irons and resulted in the formation of Al-Al3Fe eutectic structure. Microhardness profiles along cross section and top surface of the treated layers indicated that laser surface alloying with iron enhanced the hardness of the aluminum to more than twice of that of the base material.

  4. Advanced Technologies for Determination of Surface Cleanliness

    Science.gov (United States)

    Kudlacek, Jan; Chabera, Petr

    2014-12-01

    For high utility value of products is significant quality of surface treatment. Among the processes that most affect the quality of surface treatment are mainly surface pretreatment processes, namely processes of cleaning (degreasing). This article is devoted to quality control after surface pre-treatment. It mainly deals with the modern method for detecting surface contamination grease based on fluorescence methods. Impurities such as grease, oil and other have characteristic fluorescence after illumination by UV source. This principle can be used to determine the purity of the substrate surface, thereby ensuring the quality of the surface. Surface cleanliness is very important factor for the correct application of subsequent technological processes.

  5. Determination of ferrous and total iron in refractory spinels

    Energy Technology Data Exchange (ETDEWEB)

    Amonette, James E.; Matyas, Josef

    2015-12-30

    Accurate and precise determination of the redox state of iron (Fe) in spinels presents a significant challenge due to their refractory nature. The resultant extreme conditions needed to obtain complete dissolution generally oxidize some of the Fe(II) initially present and thus prevent the use of colorimetric methods for Fe(II) measurements. To overcome this challenge we developed a hybrid oxidimetric/colorimetric approach, using Ag(I) as the oxidimetric reagent for determination of Fe(II) and 1,10-phenanthroline as the colorimetric reagent for determination of total Fe. This approach, which allows determination of Fe(II) and total Fe on the same sample, was tested on a series of four geochemical reference materials and then applied to the analysis of Fe(Ni) spinel crystals isolated from simulated high-level-waste (HLW) glass and of several reagent magnetites. Results for the reference materials were in excellent agreement with published values, with the exception of USGS BIR-1, for which higher Fe(II) values and lower total Fe values were obtained. The Fe(Ni) spinels showed Fe(II) values at the detection limit (ca. 0.05 wt% Fe) and total Fe values slightly higher than obtained by total elemental analysis. For the magnetite samples, total Fe values were in agreement with reference results, but a wide range in Fe(II) values was obtained indicating various degrees of conversion to maghemite.

  6. Volcanic ash as an iron-fertilizer in ocean surface water

    Science.gov (United States)

    Olgun, N.; Duggen, S.; Croot, P.; Dietze, H.; Schacht, U.; Oskarsson, N.; Siebe, C.; Auer, A.

    2007-12-01

    Surface ocean fertilisation with iron may affect the marine primary productivity, C-cycles and eventually climate development. Volcanic ash has the potential to release iron on contact with seawater and to stimulate phytoplankton growth (1,2) but the relative importance of volcanism at destructive plate margins (subduction zones, SZ) and intraplate volcanic settings (ocean islands at hot spots) remains unknown. Here we present new results from geochemical experiments with natural seawater and numerous volcanic ash samples from SZ volcanoes in the Pacific Ring of Fire (Alaska, Japan, Kamchatka, Northern and Central America and Papua New Guinea) and hot spot volcanoes (on Iceland and Hawaii). The release of iron as a function of time was determined in situ in seawater by means of Cathodic Stripping Voltammetry. Our experiments show that: A) volcanic ash from both SZ and hot spot volcanic areas mobilise significant amounts of iron, B) with the highest mobilisation rates within the first 10-20 minutes and C) indicate that volcanic ash from hot spot volcanoes mobilise less iron than volcanic ash from SZ. We propose that the higher iron-mobilisation potential of SZ volcanic ash results from higher HCl/HF ratios in SZ volcanic gases that seem to be involved in the formation of Fe-bearing soluble salt coatings (condensed gases and adsorbed aerosols) on ash particles (1,2,3). Higher HCl/HF ratios in SZ volcanic gases thus appear to be linked to the recycling of seawater through subduction of oceanic lithosphere at destructive plate margins. Together, taking into account differences in ash-fluxes from SZ and hot spot volcanoes into the oceans, our study suggests that SZ volcanic ash plays a more important role for the global surface ocean iron budget than ash from volcanoes in hot spot areas. 1 Frogner, Gislason, Oskarsson (2001). Geology, 29, 487-490. 2 Duggen, Croot, Schacht, Hofmann (2007) Geoph. Res. Letters 34, 5. 3 Oskarsson (1980), J. Volc. and Geoth. Res. 8, 251-266.

  7. Recent advances in surface chemistry strategies for the fabrication of functional iron oxide based magnetic nanoparticles

    Science.gov (United States)

    Turcheniuk, Kostiantyn; Tarasevych, Arkadii V.; Kukhar, Valeriy P.; Boukherroub, Rabah; Szunerits, Sabine

    2013-10-01

    The synthesis of superparamagnetic nanostructures, especially iron-oxide based nanoparticles (IONPs), with appropriate surface functional groups has been intensively researched for many high-technological applications, including high density data storage, biosensing and biomedicine. In medicine, IONPs are nowadays widely used as contrast agents for magnetic resonance imaging (MRI), in hyperthermia therapy, but are also exploited for drug and gene delivery, detoxification of biological fluids or immunoassays, as they are relatively non-toxic. The use of magnetic particles in vivo requires IONPs to have high magnetization values, diameters below 100 nm with overall narrow size distribution and long time stability in biological fluids. Due to the high surface energies of IONPs agglomeration over time is often encountered. It is thus of prime importance to modify their surface to prevent aggregation and to limit non-specific adsorption of biomolecules onto their surface. Such chemical modifications result in IONPs being well-dispersed and biocompatible, and allow for targeted delivery and specific interactions. The chemical nature of IONPs thus determines not only the overall size of the colloid, but also plays a significant role for in vivo and in vitro applications. This review discusses the different concepts currently used for the surface functionalization and coating of iron oxide nanoparticles. The diverse strategies for the covalent linking of drugs, proteins, enzymes, antibodies, and nucleotides will be discussed and the chemically relevant steps will be explained in detail.

  8. Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications.

    Science.gov (United States)

    Wu, Wei; Jiang, Chang Zhong; Roy, Vellaisamy A L

    2016-12-01

    Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.

  9. New Possibilities of Shaping the Surface Properties in Austempered Ductile Iron Castings

    OpenAIRE

    D. Myszka

    2013-01-01

    The paper presents recent developments concerning the formation of surface layer in austempered ductile iron castings. It was found thatthe traditional methods used to change the properties of the surface layer, i.e. the effect of protective atmosphere during austenitising or shot peening, are not fully satisfactory to meet the demands of commercial applications. Therefore, new ways to shape the surface layer and the surface properties of austempered ductile iron castings are searched for, to...

  10. Reactions of metal ions at surfaces of hydrous iron oxide

    Science.gov (United States)

    Hem, J.D.

    1977-01-01

    Cu, Ag and Cr concentrations in natural water may be lowered by mild chemical reduction involving ferric hydroxide-ferrous ion redox processes. V and Mo solubilities may be controlled by precipitation of ferrous vanadate or molybdate. Concentrations as low as 10-8.00 or 10-9.00 M are readily attainable for all these metals in oxygen-depleted systems that are relatively rich in Fe. Deposition of manganese oxides such as Mn3O4 can be catalyzed in oxygenated water by coupling to ferrous-ferric redox reactions. Once formed, these oxides may disproportionate, giving Mn4+ oxides. This reaction produces strongly oxidizing conditions at manganese oxide surfaces. The solubility of As is significantly influenced by ferric iron only at low pH. Spinel structures such as chromite or ferrites of Cu, Ni, and Zn, are very stable and if locally developed on ferric hydroxide surfaces could bring about solubilities much below 10-9.00 M for divalent metals near neutral pH. Solubilities calculated from thermodynamic data are shown graphically and compared with observed concentrations in some natural systems. ?? 1977.

  11. Dynamic light scattering-based method to determine primary particle size of iron oxide nanoparticles in simulated gastrointestinal fluid.

    Science.gov (United States)

    Yang, Seung-Chul; Paik, Sae-Yeol-Rim; Ryu, Jina; Choi, Kyeong-Ok; Kang, Tae Seok; Lee, Jong Kwon; Song, Chi Won; Ko, Sanghoon

    2014-10-15

    Simple dynamic light scattering (DLS)-based methodologies were developed to determine primary particle size distribution of iron oxide particles in simulated gastrointestinal fluid. Iron oxide particles, which easily agglomerate in aqueous media, were converted into dispersed particles by modification of surface charge using citric acid and sodium citrate. After the modification, zeta-potential value decreased to -40mV at pH 7. Mean particle diameters in suspensions of iron oxide nano- and microparticles stabilized by the mixture of citric acid and sodium citrate were dramatically decreased to 166 and 358nm, respectively, which were close to the particle size distributions observed in the micrographs. In simulated gastrointestinal fluid, both iron oxide nano- and microparticles were heavily agglomerated with particle diameters of almost 2600 and 5200nm, respectively, due to charge shielding on the citrate-modified surface by ions in the media. For determining primary particle size distribution by using DLS-based approach, the iron oxide particles incubated in the simulated gastrointestinal fluid were converted to monodisperse particles by altering the pH to 7 and electrolyte elimination. The simple DLS-based methodologies are well suited to determine primary particle size distribution of mineral nanoparticles at various physical, chemical, and biological conditions.

  12. Surface Hydrophilicity and Functional Group-Driven Iron(III) Hydroxide Nucleation on Organic-Coated Substrates in Aqueous Environments

    Science.gov (United States)

    Ray, J.; Lee, B.; Baltrusaitis, J.; Jun, Y.

    2012-12-01

    Homogeneous and heterogeneous iron hydroxide nanoparticle nucleation can occur continuously in both natural and complex aqueous systems. Iron oxide nanoparticles can act as sinks and/or carriers for heavy metal contaminants; therefore, it is important to develop a better understanding of factors affecting their formation. Organic coatings are ubiquitous in aqueous environments where they can exist on mineral surfaces (e.g., biofilm), as nanoparticle surface coatings (e.g., natural organic matter), or be introduced as coagulants in water treatment systems. These surface coatings could influence the formation of iron oxide nanoparticles and thus, the mobility of aqueous contaminants. Therefore, to better understand the fate and transport of contaminants in complex aqueous environments, we need more accurate information about mechanisms governing heterogeneous and homogeneous nucleation and growth of iron(III) hydroxide nanoparticles in the presence of organic surface coatings. In this work, we used a unique measurement technique allowing for simultaneous small-angle X-ray scattering (SAXS) and grazing incidence (GISAXS) analysis to monitor nanoparticle nucleation in solution and at substrate surfaces. Clean quartz, and polyaspartate- and alginate-coated substrates were chosen as model substrates to represent mineral coatings, engineered organic coatings and natural organic coatings. Polyaspartate was determined to be the most negatively charged substrate and quartz to be the least negatively charged substrate; however, after 2 h of reaction, the total nanoparticle volume calculations—determined from GISAXS—indicate that precipitation of positively-charged iron(III) hydroxide nanoparticles is 10 times higher on the quartz substrate than on the polyaspartate substrate. This implies that electrostatics do not govern iron(III) hydroxide nucleation. Furthermore, homogeneous nucleation approximately 250 μm above the substrate surface was highest in the presence of the

  13. Water determination in iron oxyhydroxides and iron ores by Karl Fischer titration

    Science.gov (United States)

    da Cunha, Camila C. R. F.; da Costa, Geraldo M.

    2016-08-01

    Protohematite (Fe2-x/3(OH) x O3-x 1 ≤ x hydroxyl groups in their structures. These species were described in prior studies mainly with the aid of X-ray diffraction and Infrared spectroscopy. The existence of these phases in soils might have influence in redox processes, and they were considered as a possible water reservoir in Martian soils. In this study, we have used for the first time the Karl Fischer titration method to determine the amount of water released after heating several synthetic samples of goethite, hematite and natural iron ores at 105, 400, 600 and 900 °C. It was found that heating at 105 °C did not remove all moisture from the samples, and higher temperatures were necessary to completely remove all the absorbed water. The water contents determined at 400, 600 and 900 °C were found to be the same within the experimental errors, suggesting the inexistence of both protohematite and hydrohematite in the investigated samples. Therefore, the above-mentioned effects of these phases in soils might have to be reevaluated.

  14. A Case Study on the Strata Movement Mechanism and Surface Deformation Regulation in Chengchao Underground Iron Mine

    Science.gov (United States)

    Cheng, Guanwen; Chen, Congxin; Ma, Tianhui; Liu, Hongyuan; Tang, Chunan

    2017-04-01

    The regular pattern of surface deformation and the mechanism of underground strata movement, especially in iron mines constructed with the block caving method, have a great influence on infrastructure on the surface, so they are an important topic for research. Based on the engineering geology conditions and the surface deformation and fracture features in Chengchao Iron Mine, the mechanism of strata movement and the regular pattern of surface deformation in the footwall were studied by the geomechanical method, and the following conclusions can be drawn: I. The surface deformation process is divided into two stages over time, i.e., the chimney caving development stage and the post-chimney deformation stage. Currently, the surface deformation in Chengchao Iron Mine is at the post-chimney deformation stage. II. At the post-chimney deformation stage, the surface deformation and geological hazards in Chengchao Iron Mine are primarily controlled by the NWW-trending joints, with the phenomenon of toppling deformation and failure on the surface. Based on the surface deformation characteristics in Chengchao Iron Mine, the surface deformation area can be divided into the following four zones: the fracture extension zone, the fracture closure zone, the fracture formation zone and the deformation accumulation zone. The zones on the surface can be determined by the surface deformation characteristics. III. The cantilever beams near the chimney caving area, caused by the NWW-trending joints, have been subjected to toppling failure. This causes the different deformation and failure mechanisms in different locations of the deep rock mass. The deep rock can be divided into four zones, i.e., the fracture zone, fracture transition zone, deformation zone and undisturbed zone, according to the different deformation and failure mechanisms. The zones in the deep rock are the reason for the zones on the surface, so they can be determined by the zones on the surface. Through these

  15. Droplet impinging behavior on surfaces: Part II - Water on aluminium and cast iron surfaces

    Science.gov (United States)

    Sangavi, S.; Balaji, S.; Mithran, N.; Venkatesan, M.

    2016-09-01

    Droplet cooling of metal surfaces is an important area of research in industrial applications such as material quenching, nozzle spraying, etc. Fluids (water) act as an excellent agent in heat transfer to remove excess heat in various processes by convection and conduction. Such cooling process varies the material properties. The bubbles formed during droplet impinging on the surface act as heat sink and causes variation of height and spreading radius of the droplet with increase in temperature. In the present work, an experimental study of the droplet impinging behavior on Aluminium and Cast iron surfaces is reported. The water droplets are made to fall on the surface of the specimens from a specific height, which also influences the spreading radius. The effect of temperature on droplet height and droplet spreading radius is detailed.

  16. Iron organic speciation determination in rainwater using cathodic stripping voltammetry.

    Science.gov (United States)

    Cheize, Marie; Sarthou, Géraldine; Croot, Peter L; Bucciarelli, Eva; Baudoux, Anne-Claire; Baker, Alex R

    2012-07-29

    A sensitive method using Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) has been developed to determine for the first time iron (Fe) organic speciation in rainwater over the typical natural range of pH. We have adapted techniques previously developed in other natural waters to rainwater samples, using the competing ligand 1-nitroso-2-naphthol (NN). The blank was equal to 0.17±0.05 nM (n=14) and the detection limit (DL) for labile Fe was 0.15 nM which is 10-70 times lower than that of previously published methods. The conditional stability constant for NN under rainwater conditions was calibrated over the pH range 5.52-6.20 through competition with ethylenediaminetetraacetic acid (EDTA). The calculated value of the logarithm of β'(Fe(3+)(NN)(3)) increased linearly with increasing pH according to log β'(Fe(3+)(NN)(3)) (salinity=2.9, T=20 °C). The validation of the method was carried out using desferrioxamine mesylate B (DFOB) as a natural model ligand for Fe. Adequate detection windows were defined to detect this class of ligands in rainwater with 40 μM of NN from pH 5.52 to 6.20. The concentration of Fe-complexing natural ligands was determined for the first time in three unfiltered and one filtered rainwater samples. Organic Fe-complexing ligand concentrations varied from 104.2±4.1 nM equivalent of Fe(III) to 336.2±19.0 nM equivalent of Fe(III) and the logarithm of the conditional stability constants, with respect to Fe(3+), varied from 21.1±0.2 to 22.8±0.3. This method will provide important data for improving our understanding of the role of wet deposition in the biogeochemical cycling of iron. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Iron Oxide Surface Chemistry: The Effect of Chemical Structure on Binding in Benzoic Acid and Catechol Derivatives.

    Science.gov (United States)

    Korpany, Katalin V; Majewski, Dorothy D; Chiu, Cindy T; Cross, Shoronia N; Blum, Amy Szuchmacher

    2017-02-18

    Excellent performance of functionalized iron oxide nanoparticles in nanomaterial and biomedical applications often relies on achieving attachment of ligands to the iron oxide surface both in sufficient number and with proper orientation. Towards this end, we determine relationships between ligand chemical structure and surface binding on magnetic iron oxide nanoparticles for a series of related benzoic acid and catechol derivatives. Ligand exchange was used to introduce the model ligands, and the resulting nanoparticles were characterized by FTIR-ATR, transmission electron microscopy (TEM), and nanoparticle solubility behavior. An in-depth analysis of ligand electronic effects and reaction conditions reveals that the nature of ligand binding does not solely depend on the presence of functional groups known to bind to iron oxide nanoparticles. The structure of the resulting ligand-surface complex was primarily influenced by the relative positioning of hydroxyl and carboxylic acid groups within the ligand as well as whether or not HCl(aq) was added to the ligand exchange reaction. Overall, this study will help guide future ligand design and ligand exchange strategies towards realizing truly custom-built iron oxide nanoparticles.

  18. EVALUATION OF MACHINABILITY OF DUCTILE IRONS ALLOYED WITH Ni AND Cu IN TERMS OF CUTTING FORCES AND SURFACE QUALITY

    Directory of Open Access Journals (Sweden)

    Yücel AŞKUN

    2003-02-01

    Full Text Available Due to the enhanced strength, ductility and thoughness of Ductile Iron (DI when compared to the other types cast iron, its machinability is relatively poor. When a steel part is replaced with ductile iron, however, better machinability is considered to be the most important gain. This study presents the results of machining tests of ductile irons alloyed with Ni and Cu at various contents to determine the effect of their microstructure and mechanical properties on cutting forces and surface roughness. Six different specimen groups of ductile iron alloyed with various amounts of nickel and copper were subjected to machining tests and their machinabilities were investigated based on cutting forces and surface roughness criteria. The results were evaluated according to microstructure and mechanical properties of specimens determined before. In terms of both criterion, the best result obtained was specimen added 0.7 % Ni and 0.7 % Cu. When the specimens were evaluated according to their mechanical properties, the specimens alloyed 1 % Ni and 0.65 % Cu seemed promising.

  19. Prevalence and Determinants of Anemia and Iron Deficiency in Kuwait.

    Science.gov (United States)

    Al Zenki, Sameer; Alomirah, Husam; Al Hooti, Suad; Al Hamad, Nawal; Jackson, Robert T; Rao, Aravinda; Al Jahmah, Nasser; Al Obaid, Ina'am; Al Ghanim, Jameela; Al Somaie, Mona; Zaghloul, Sahar; Al Othman, Amani

    2015-07-31

    The objective of this study was to assess the prevalence of anemia and iron deficiency (ID) of a nationally representative sample of the Kuwait population. We also determined if anemia differed by socioeconomic status or by RBC folate and vitamins A and B12 levels. The subjects who were made up of 1830 males and females between the ages of 2 months to 86 years, were divided into the following age groups (0-5, 5-11, 12-14, 15-19, 20-49, ≥50 years). Results showed that the prevalence of anemia was 3% in adult males and 17% in females. The prevalence of ID varied according to age between 4% (≥50 years) and 21% (5-11 years) and 9% (12-14 years) and 23% (15-19 years), respectively, in males and females. The prevalence of anemia and ID was higher in females compared to males. Adults with normal ferritin level, but with low RBC folate and vitamins A and B12 levels had higher prevalence of anemia than those with normal RBC folate and vitamins A and B12 levels. This first nationally representative nutrition and health survey in Kuwait indicated that anemia and ID are prevalent and ID contributes significantly to anemia prevalence.

  20. Determination of Dietary Iron Requirements by Full Expression of Iron-Containing Enzymes in Various Tissues of Broilers.

    Science.gov (United States)

    Ma, Xinyan; Liao, Xiudong; Lu, Lin; Li, Sufen; Zhang, Liyang; Luo, Xugang

    2016-11-01

    The current dietary iron requirement (80 mg/kg) of broilers is mainly based on growth, hemoglobin concentration, or hematocrit data obtained in a few early studies; however, expressions of iron-containing enzymes might be more sensitive novel criteria to evaluate dietary iron requirements. The objective of this study was to determine dietary iron requirements of broilers for the full expression of succinate dehydrogenase (SDH), catalase, and cytochrome c oxidase (COX) in various tissues. A total of 336 1-d-old Arbor Acres male chicks were randomly assigned to 1 of 7 treatments with 6 replicates and fed a basal corn and soybean-meal diet (control, containing 67 mg Fe/kg) and the basal diet supplemented with 20, 40, 60, 80, 100, or 120 mg Fe/kg from FeSO4 ⋅ 7H2O for 21 d. Regression analysis was performed to estimate the optimal dietary iron concentration with the use of broken-line or quadratic models. SDH activity in the liver and heart, COX and catalase activity in the liver, Sdh mRNA levels in the liver, and Cox mRNA levels in the liver and heart of broilers were affected (P requirements estimated on the basis of fitted broken-line or quadratic-curve models (P requirements of broilers, and the dietary iron requirements would be 97-136 mg/kg to support the full expression of the above iron-containing enzymes in various tissues of broiler chicks from 1 to 21 d of age, which are higher than the current NRC iron requirement. © 2016 American Society for Nutrition.

  1. Influence of the Lubricant Type on the Surface Quality of Steel Parts Obtained by Ironing

    Directory of Open Access Journals (Sweden)

    D. Adamović

    2015-06-01

    Full Text Available If it is needed to achieve a higher strain rate during the ironing process, which is possible without inter-stage annealing, the ironing is performed in succession through multiple dies. During that process, changes of friction conditions occur due to the change of contact conditions (dislodging of lubricants, changes of surface roughness, formation of friction junctions, etc.. In the multistage ironing, after each stage, the completely new conditions on the contact surfaces occur, which will significantly affect the quality of the workpiece surface. Lubricant has a very important role during the steel sheet metal ironing process; to separate the sheet metal surface from the tool and to reduce the friction between the contact surfaces. The influence of tribological conditions in ironing process is extremely important and it was a subject of study among researches in recent years, both in the real processes and on the tribo-models. Investigation of tribological conditions in the real processes is much longer and more expensive, so testing on the tribo-models is more frequent. Experimental research on the original tribo-model presented in this paper was aimed to indicate the changes that occur during multistage ironing, as well as to consider the impact of some factors (tool material, lubricant on die and punch on increase or decrease of the sheet metal surface roughness in ironing stages.

  2. Effect of solvent and silicon substrate surface on the size of iron nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Phillip; Milev, Adriyan, E-mail: A.Milev@uws.edu.au; Kannangara, Kamali [University of Western Sydney, School of Science and Health (Australia); Martin, Philip [CSIRO Lindfield, Materials Science and Engineering (Australia)

    2015-04-15

    The diameter of carbon nanotubes is strongly related the geometric sizes of the metal particles upon which they are nucleated. To improve the control over the nanoparticle sizes derived from iron acetate and deposited on Si substrates, two different approaches were employed; manipulation of the solvent chemistry and manipulation of the Si substrate surface. The iron acetate was dissolved separately in pure water and ethanol and in binary ethanol/water mixtures. Silicon substrates, with either smooth surface or nano-porous surface, were dip coated using these solutions. The dip-coated substrates were first thermally oxidised at 400 °C in air followed by reduction at 800 °C in an Ar/H{sub 2} gas mixture. As derived particles were measured by scanning electron microscopy, and the average size and size distribution were determined by statistical analysis. Electron microscopy and statistical analyses demonstrated that metal particles deposited onto the smooth Si wafer have sizes ranging from 18 to 160 nm based on the solvent used, where the pure solvents resulted in a narrower size distribution when compared to the water/ethanol mixtures. When nano-porous Si wafer is used as a substrate, the metal particle diameter distributions are reduced to a range from 11 to 17 nm contingent upon the solvent used. The role of the ethanol/water interactions investigated by vibrational (IR and Raman) and {sup 1}H nuclear magnetic resonance spectroscopy on nanoparticle sizes and size distributions is discussed.

  3. Microstructure and hardness of WC-Co particle reinforced iron matrix surface composite

    Directory of Open Access Journals (Sweden)

    Zhang Peng

    2013-11-01

    Full Text Available In this study, a high Cr cast iron surface composite material reinforced with WC-Co particles 2-6 mm in size was prepared using a pressureless sand mold infiltration casting technique. The composition, microstructure and hardness were determined by means of energy dispersive spectrometry (EDS, electron probe microanalysis (EPMA, scanning electron microscope (SEM and Rockwell hardness measurements. It is determined that the obtained composite layer is about 15 mm thick with a WC-Co particle volumetric fraction of ~38%. During solidification, interface reaction takes place between WC-Co particles and high chromium cast iron. Melting and dissolving of prefabricated particles are also found, suggesting that local Co melting and diffusion play an important role in promoting interface metallurgical bonding. The composite layer is composed of ferrite and a series of carbides, such as (Cr, W, Fe23C6, WC, W2C, M6C and M12C. The inhomogeneous hardness in the obtained composite material shows a gradient decrease from the particle reinforced metal matrix composite layer to the matrix layer. The maximum hardness of 86.3 HRA (69.5 HRC is obtained on the particle reinforced surface, strongly indicating that the composite can be used as wear resistant material.

  4. Determination of Trace Iron in High Purity Sodium Fluoride by Graphite Furnace Atomic Absorption Spectrometry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A method is described for the direct determination of iron in high purity sodium fluoride using graphite furnace atomic absorption spectrometry. Interferences caused by the matrix are investigated. It is shown that the ashing temperature can be increased to 1 400°C and matrix interferences eliminated, the sensi tivity of iron increased in 1.27 fold by the addition of nickel nitrate. The method is applied to the determina tion of iron in sodium fluoride and satisfactory results are obtained.

  5. Determination of ferrous and total iron in refractory spinels

    Energy Technology Data Exchange (ETDEWEB)

    Amonette, J.E. [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Matyáš, J. [Material Science Department, Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2016-03-03

    Accurate and precise determination of the redox state of iron (Fe) in spinels presents a significant challenge due to their refractory nature. The resultant extreme conditions needed to obtain complete dissolution generally oxidize some of the Fe(II) initially present and thus prevent the use of colorimetric methods for Fe(II) measurements. To overcome this challenge we developed a hybrid oxidimetric/colorimetric approach, using Ag(I) as the oxidimetric reagent for determination of Fe(II) and 1,10-phenanthroline as the colorimetric reagent for determination of total Fe. This approach, which allows determination of Fe(II) and total Fe on the same sample, was tested on a series of four geochemical reference materials and then applied to the analysis of Fe(Ni) spinel crystals isolated from simulated high-level-waste (HLW) glass and of several reagent magnetites. Results for the reference materials were in excellent agreement with recommended values, with the exception of USGS BIR-1, for which higher Fe(II) values and lower total Fe values were obtained. The Fe(Ni) spinels showed Fe(II) values at the detection limit (ca. 0.03 wt% Fe) and total Fe values higher than obtained by ICP-AES analysis after decomposition by lithium metaborate/tetraborate fusion. For the magnetite samples, total Fe values were in agreement with reference results, but a wide range in Fe(II) values was obtained indicating various degrees of conversion to maghemite. Formal comparisons of accuracy and precision were made with 13 existing methods. Accuracy for Fe(II) and total Fe was at or near the top of the group. Precision varied with the parameter used to measure it but was generally in the middle to upper part of the group for Fe(II) while that for total Fe ranged from the bottom of the group to near the top. - Highlights: • Refractory samples, such as spinels, are the most difficult for Fe redox analysis. • Oxidimetric(Ag{sup +})/colorimetric (phen) method allows analysis of a single

  6. Determining Electrochemical Surface Stress of Single Nanowires.

    Science.gov (United States)

    Wang, Hui; Shan, Xiaonan; Yu, Hui; Wang, Yan; Schmickler, Wolfgang; Chen, Hong-Yuan; Tao, Nongjian

    2017-02-13

    Electrochemical surface stress is important in nanomaterials because of their large surface-to-volume ratios, which lead to unique mechanical and electrocatalytic properties, but directly measuring this quantity has been challenging. Here we report on experimental determination of the surface stress, and associated electrochemical processes of a single gold nanowire with an optical imaging technique. We show that surface stress changes linearly and reversibly with the potential between 0 and 0.8 V versus Ag/AgCl, but abruptly with large hysteresis, associated with the oxidation and reduction of the nanowire, between 0.8 and 1.5 V. The potential derivative of the surface stress closely resembles the cyclic voltammograms. We described the observations in terms of anion adsorption and surface oxidation/reduction. This work demonstrates a new approach to study electrochemical processes and the associated surface stress changes of nanomaterials.

  7. Polymers' surface interactions with molten iron: A theoretical study

    Science.gov (United States)

    Assadi, M. Hussein N.; Sahajwalla, Veena

    2014-10-01

    Environmental concerns are the chief drive for more innovative recycling techniques for end-of-life polymeric products. One attractive option is taking advantage of C and H content of polymeric waste in steelmaking industry. In this work, we examined the interaction of two high production polymers i.e. polyurethane and polysulfide with molten iron using ab initio molecular dynamics simulation. We demonstrate that both polymers can be used as carburizers for molten iron. Additionally, we found that light weight H2 and CHx molecules were released as by-products of the polymer-molten iron interaction. The outcomes of this study will have applications in the carburization of molten iron during ladle metallurgy and waste plastic injection in electric arc furnace.

  8. Determinants of iron accumulation in deep grey matter of multiple sclerosis patients

    DEFF Research Database (Denmark)

    Ropele, Stefan; Kilsdonk, Iris D; Wattjes, Mike P

    2014-01-01

    BACKGROUND: Iron accumulation in deep grey matter (GM) structures is a consistent finding in multiple sclerosis (MS) patients. This study focused on the identification of independent determinants of iron accumulation using R2* mapping. SUBJECTS AND METHODS: Ninety-seven MS patients and 81 healthy...

  9. Core size determination and structural characterization of intravenous iron complexes by cryogenic transmission electron microscopy.

    Science.gov (United States)

    Wu, Yong; Petrochenko, Peter; Chen, Lynn; Wong, Sook Yee; Absar, Mohammad; Choi, Stephanie; Zheng, Jiwen

    2016-05-30

    Understanding physicochemical properties of intravenous (IV) iron drug products is essential to ensure the manufacturing process is consistent and streamlined. The history of physicochemical characterization of IV iron complex formulations stretches over several decades, with disparities in iron core size and particle morphology as the major source of debate. One of the main reasons for this controversy is room temperature sample preparation artifacts, which affect accurate determination of size, shape and agglomeration/aggregation of nanoscale iron particles. The present study is first to report the ultra-fine iron core structures of four IV iron complex formulations, sodium ferric gluconate, iron sucrose, low molecular weight iron dextran and ferumoxytol, using a cryogenic transmission electron microscopy (cryo-TEM) preservation technique, as opposed to the conventional room temperature (RT-TEM) technique. Our results show that room temperature preparation causes nanoparticle aggregation and deformation, while cryo-TEM preserves IV iron colloidal suspension in their native frozen-hydrated and undiluted state. In contrast to the current consensus in literature, all four IV iron colloids exhibit a similar morphology of their iron oxide cores with a spherical shape, narrow size distribution and an average size of 2nm. Moreover, out of the four tested formulations, ferumoxytol exhibits a cluster-like community of several iron carbohydrate particles which likely accounts for its large hydrodynamic size of 25nm, measured with dynamic light scattering. Our findings outline a suitable method for identifying colloidal nanoparticle core size in the native state, which is increasingly important for manufacturing and design control of complex drug formulations, such as IV iron drug products.

  10. Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications.

    Science.gov (United States)

    Gupta, Ajay Kumar; Gupta, Mona

    2005-06-01

    Superparamagnetic iron oxide nanoparticles (SPION) with appropriate surface chemistry have been widely used experimentally for numerous in vivo applications such as magnetic resonance imaging contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, hyperthermia, drug delivery and in cell separation, etc. All these biomedical and bioengineering applications require that these nanoparticles have high magnetization values and size smaller than 100 nm with overall narrow particle size distribution, so that the particles have uniform physical and chemical properties. In addition, these applications need special surface coating of the magnetic particles, which has to be not only non-toxic and biocompatible but also allow a targetable delivery with particle localization in a specific area. To this end, most work in this field has been done in improving the biocompatibility of the materials, but only a few scientific investigations and developments have been carried out in improving the quality of magnetic particles, their size distribution, their shape and surface in addition to characterizing them to get a protocol for the quality control of these particles. Nature of surface coatings and their subsequent geometric arrangement on the nanoparticles determine not only the overall size of the colloid but also play a significant role in biokinetics and biodistribution of nanoparticles in the body. The types of specific coating, or derivatization, for these nanoparticles depend on the end application and should be chosen by keeping a particular application in mind, whether it be aimed at inflammation response or anti-cancer agents. Magnetic nanoparticles can bind to drugs, proteins, enzymes, antibodies, or nucleotides and can be directed to an organ, tissue, or tumour using an external magnetic field or can be heated in alternating magnetic fields for use in hyperthermia. This review discusses the synthetic chemistry, fluid stabilization and

  11. A cell-surface receptor for lipocalin 24p3 selectively mediates apoptosis and iron uptake.

    Science.gov (United States)

    Devireddy, Laxminarayana R; Gazin, Claude; Zhu, Xiaochun; Green, Michael R

    2005-12-29

    The lipocalin mouse 24p3 has been implicated in diverse physiological processes, including apoptosis due to interleukin-3 (IL-3) deprivation and iron transport. Here we report cloning of the 24p3 cell-surface receptor (24p3R). Ectopic 24p3R expression confers on cells the ability to undergo either iron uptake or apoptosis, dependent upon the iron content of the ligand: Iron-loaded 24p3 increases intracellular iron concentration without promoting apoptosis; iron-lacking 24p3 decreases intracellular iron levels, which induces expression of the proapoptotic protein Bim, resulting in apoptosis. Intracellular iron delivery blocks Bim induction and suppresses apoptosis due to 24p3 addition or IL-3 deprivation. We find, unexpectedly, that the BCR-ABL oncoprotein activates expression of 24p3 and represses 24p3R expression, rendering BCR-ABL(+) cells refractory to secreted 24p3. By inhibiting BCR-ABL, imatinib induces 24p3R expression and, consequently, apoptosis. Our results reveal an unanticipated role for intracellular iron regulation in an apoptotic pathway relevant to BCR-ABL-induced myeloproliferative disease and its treatment.

  12. New Possibilities of Shaping the Surface Properties in Austempered Ductile Iron Castings

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2013-01-01

    Full Text Available The paper presents recent developments concerning the formation of surface layer in austempered ductile iron castings. It was found thatthe traditional methods used to change the properties of the surface layer, i.e. the effect of protective atmosphere during austenitising or shot peening, are not fully satisfactory to meet the demands of commercial applications. Therefore, new ways to shape the surface layer and the surface properties of austempered ductile iron castings are searched for, to mention only detonation spraying, carbonitriding, CVD methods, etc.

  13. Determinants of compliance to iron supplementation among pregnant women in Enugu, Southeastern Nigeria.

    Science.gov (United States)

    Ugwu, E O; Olibe, A O; Obi, S N; Ugwu, A O

    2014-01-01

    Anemia in pregnancy is highly prevalent among antenatal clinic attendees in Enugu, Nigeria despite the practice of routine iron supplementation in pregnancy. The major problem with iron supplementation in pregnancy is compliance, and this may be a potential driver to the persistent high prevalence of anemia in this population. To find out the compliance rate and determinants of compliance to iron supplementation among pregnant women in Enugu, southeastern Nigeria. This was a questionnaire-based cross-sectional study of eligible pregnant women receiving antenatal care at the University of Nigeria Teaching Hospital (UNTH), Ituku/Ozalla, Enugu, Nigeria between April 1, 2012 and January 31, 2013. The knowledge of iron supplementation was 76.3% ( n = 302), however, the compliance rate was 65.9% ( n = 261). Tertiary level of education and high social class were factors significantly associated with compliance to iron supplementation after adjusting for other factors in the binary logistic regression analysis ( P compliance to iron supplementation included gastrointestinal side effects of iron supplements (41.7%), non-affordability of iron supplements (28.3%), and forgetfulness (15.0%) among the antenatal mothers. The compliance rate of 65.9% for iron supplementation by pregnant mothers in Enugu can further be improved by providing the drug free of charge in the short term and improvement in education and socioeconomic class of the populace in the long run.

  14. Formation of VC- composites surface layers on spheroidized graphite cast iron by laser surface cladding process

    Directory of Open Access Journals (Sweden)

    Essam R.I. Mahmoud

    2015-01-01

    Full Text Available Spheroidal graphite cast iron was laser cladded with VC powder of 44-53 μm particle size using YAG Fiber laser at 500, 1000, and 1500 W processing power and fixed travelling speed of 4 mm/s. The powder was preplaced on the surface of the specimens with 0.5 mm thickness. To prevent the oxidation, argon gas was used as a shielding gas. After the treatment, three zones were resulted: build-up (cladding, fusion, and heat affected zones. The build-up zone was a composite structure consisted of VC particles/dendrites dispersed in a matrix of martensite, carbides and ledeburite structure. At 500 W, most of the VC particles were appeared as their original large size. When the laser power was increased to 1000 W or more, the VC particles were melted and then re-solidified in the form of fine dendrites. The surface hardness of the cladded area was remarkably improved. As the distance from the free surface increases, the hardness decreases. The average hardness value at the surface treated by 500 W was about 710 HV (3 times of the hardness of substrate, while it reached to about 1340 HV and 1520 HV at powers of 1000 W and 1500 W, respectively. The wear resistance of the laser treated samples was improved at all investigated laser processing powers, especially at 1000W and 1500 W.

  15. Electron transfer between iron minerals and quinones: estimating the reduction potential of the Fe(II)-goethite surface from AQDS speciation.

    Science.gov (United States)

    Orsetti, Silvia; Laskov, Christine; Haderlein, Stefan B

    2013-12-17

    Redox reactions at iron mineral surfaces play an important role in controlling biogeochemical processes of natural porous media such as sediments, soils and aquifers, especially in the presence of recurrent variations in redox conditions. Ferrous iron associated with iron mineral phases forms highly reactive species and is regarded as a key factor in determining pathways, rates, and extent of chemically and microbially driven electron transfer processes across the iron mineral-water interface. Due to their transient nature and heterogeneity a detailed characterization of such surface bound Fe(II) species in terms of redox potential is still missing. To this end, we used the nonsorbing anthraquinone-2,6-disulfonate (AQDS) as a redox probe and studied the thermodynamics of its redox reactions in heterogeneous iron systems, namely goethite-Fe(II). Our results provide a thermodynamic basis for and are consistent with earlier observations on the ability of AQDS to "shuttle" electrons between microbes and iron oxide minerals. On the basis of equilibrium AQDS speciation we reported for the first time robust reduction potential measurements of reactive iron species present at goethite in aqueous systems (EH,Fe-GT ≈ -170 mV). Due to the high redox buffer intensity of heterogeneous mixed valent iron systems, this value might be characteristic for many iron-reducing environments in the subsurface at circumneutral pH. Our results corroborate the picture of a dynamic remodelling of Fe(II)/Fe(III) surface sites at goethite in response to oxidation/reduction events. As quinones play an essential role in the electron transport systems of microbes, the proposed method can be considered as a biomimetic approach to determine "effective" biogeochemical reduction potentials in heterogeneous iron systems.

  16. Determinants of iron status in Malaysian adolescents from a rural community.

    Science.gov (United States)

    Foo, Leng Huat; Khor, Geok Lin; Tee, E-Siong; Dhanaraj, Prabakaran

    2004-09-01

    Iron deficiency anaemia is the most common micronutrient deficiency worldwide. The prevalence of anaemia in the developing countries is three to four times higher than that in the developed countries. The iron status was assessed in 199 apparently healthy male and female adolescents aged 12-19 years living in a fishing community in Sabah, Malaysia. Data on socio-economic characteristics, lifestyles, anthropometry measurements, iron status, and dietary intake were gathered. Dietary intake of energy, iron, and most nutrients (with the exception of protein and vitamin C) were below the recommended levels for Malaysian adolescents. Three-quarters of the iron was derived from plant foods. The mean haemoglobin value for the male was 13.9 +/- 1.3 g/dl with 9.5% having less than 12 g/dl, while the respective figures for the female were 12.4 +/- 1.6 g/dl and 28.6%. The mean serum ferritin concentrations for male and female adolescents were 21.5 and 15.4 microg/l, respectively; with 25.7% of the males and 49.5% of the females having deficient levels of ferritin. Dietary intake of total energy and iron, and gender were found to be independent determinants of serum ferritin and haemoglobin levels, accounting for over 40% of the variations for each of these iron indicators. In males, but not in females, the intake of dietary protein and iron, and physical activity were also found to be significant determinants of serum ferritin. The age of subjects and household size were significant determinants of haemoglobin levels for male subjects, but not for female subjects. The findings indicate the importance of adequate intake of energy and dietary iron for improving the iron status of adolescents.

  17. What Oxidation State of Iron Determines the Amethyst Colour?

    Energy Technology Data Exchange (ETDEWEB)

    Dedushenko, S. K. [Moscow State University, Department of Chemistry (Russian Federation); Makhina, I. B.; Mar' in, A. A.; Mukhanov, V. A. [Russian Research Institute for Synthesis of Materials (Russian Federation); Perfiliev, Yu. D. [Moscow State University, Department of Chemistry (Russian Federation)

    2004-12-15

    A colourless quartz crystal doped with {sup 57}Fe{sup 3+} was obtained by hydrothermal synthesis in an NH{sub 4}F solution. The crystal was transformed into violet amethyst by gamma-irradiation. The change in colour was accompanied by changes in the Moessbauer spectrum that can be interpreted as the conversion of trivalent iron into the tetravalent state: Fe{sup 3+{yields}F}e{sup 4+}.

  18. A visual strip sensor for determination of iron

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sanjukta A., E-mail: sanjuktaak301@gmail.com [Analytical Chemistry Division, BARC, Trombay, Mumbai 400085 (India); Thakur, Neha; Parab, Harshala J.; Pandey, Shailaja P. [Analytical Chemistry Division, BARC, Trombay, Mumbai 400085 (India); Shinde, Rakesh N.; Pandey, Ashok K. [Radiochemistry Division, BARC, Trombay, Mumbai 400085 (India); Kumar, Sangita D.; Reddy, A.V.R. [Analytical Chemistry Division, BARC, Trombay, Mumbai 400085 (India)

    2014-12-03

    Highlights: • A visual strip sensor for on-site detection of iron has been developed and made. • The sensor is easy to synthesize, portable and recyclable with shelf life >1 year. • Visual detection limit for iron using the present sensor is 50 ng mL{sup −1}. • Visual strip sensor was applied to ground water and fruit juices. - Abstract: A visual strip has been developed for sensing iron in different aqueous samples like natural water and fruit juices. The sensor has been synthesized by UV-radiation induced graft polymerization of acrylamide monomer in microporous poly(propylene) base. For physical immobilization of iron selective reagent, the in situ polymerization of acrylamide has been carried out in the presence of 1,10-phenanthroline. The loaded strip on interaction with Fe(II) in aqueous solution turned into orange red color and the intensity of the color was found to be directly proportional to the amount of Fe(II) in the aqueous sample. The minimal sensor response with naked eye was found for 50 ng mL{sup −1} of Fe in 15 min of interaction. However, as low as 20 ng mL{sup −1} Fe could be quantified using a spectrophotometer. The detection limit calculated using the 3s/S criteria, where ‘s’ is the standard deviation of the absorbance of blank reagent loaded strip and ‘S’ is the slope of the linear calibration plot, was 1.0 ng mL{sup −1}. The strip was applied to measure Fe in a variety of samples such as ground water and fruit juices.

  19. The mechanism of changes in the surface layer of grey cast iron automotive brake disc

    Directory of Open Access Journals (Sweden)

    Adam Polak

    2005-12-01

    Full Text Available The aim of the study was to create a model, describing the run of tribological processes in the surface layer of grey cast iron automotive brake discs. Grey cast iron discs mating with non-asbestos organic brake pads were chosen for the investigations, as the most widely used materials in car brakes. Samples for surface analysis were prepared from disc operating in stand and road conditions. Stand tests were pin-on-disc kind. Operating parameters for the stand tests were chosen on the basis of results of our earlier research. Topography of brake disc surface was evaluated by surface roughness measurements. The surface layer was examined with use of metallography and scanning electron microscopy. In order to differentiate structures of grey cast iron brake discs SE and BSE modes were used in scanning electron microscopy. Chemical investigations of samples were done by X-ray analysis linked with SEM. Studies showed influence of grey cast iron structures on tribological processes taking place in a brake friction pair. The surface layer of grey cast iron discs was described and features and functions of separated structures were presented. On the basis of the obtained results a physical model of friction mechanism was created. Special attention was paid to the influence of graphite on the run of tribological processes and mechanism of compaction and removal of wear debris.

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

    Science.gov (United States)

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

    2011-07-15

    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. Copyright © 2011 Wiley Periodicals, Inc.

  1. Effect of Root Surface Iron Plaque on Se Translocation and Uptake by Fe-Deficient Rice

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Under anaerobic conditions, ferric hydroxide deposits on the surface of rice roots and affects uptake and translocation of certain nutrients. In the present study, rice plants were cultured in Fe-deficient or sufficient solutions and placed in a medium containing selenium (Se) for 2 h. Then, FeSO4 was added at the various concentrations of 0, 10, 40, or 70mg L-1 to induce varying levels of iron plaque on the root surfaces and subsequent uptake of Se was monitored. The uptake of Se was inhibited by the iron plaque, with the effect proportional to the amount of plaque induced. The activity of cysteine synthase was decreased with increasing amounts of iron plaque on the roots. This may be the important reason for iron plaque inhibition of Se translocation. At each level of iron plaque, Fe-deficient rice had more Se than Fe-sufficient rice. Furthermore, with plaque induced by 20 mg Fe L-1, plants from Fe-deficient media accumulated more Se than those from Fe-sufficient media, as the Se concentration was increased from 10 to 30 or 50 mg L-1. We found that phytosiderophores, highly effective iron chelating agents, could desorb selenite from ferrihydrite. Root exudates of the Fe-deficient rice, especially phytosiderophores in the exudates, could enhance Se uptake by rice plants with iron plaque.

  2. Iron status and its determinants in a nationally representative sample of pregnant women.

    Science.gov (United States)

    Vandevijvere, Stefanie; Amsalkhir, Sihame; Van Oyen, Herman; Egli, Ines; Ines, Egli; Moreno-Reyes, Rodrigo

    2013-05-01

    Iron-deficiency anemia is associated with adverse neonatal health outcomes. Iron status and its determinants were assessed in a representative sample of Belgian pregnant women. Blood samples were collected and a questionnaire was completed face-to-face. Hemoglobin (Hb) and mean cell volume were measured using a Beckman Coulter Hematology Analyzer and serum ferritin (SF) and transferrin receptor (sTfr) concentrations by immunoassay. In total, 55 obstetric clinics and 1,311 pregnant women were included. Approximately 40% of third-trimester and 6% of first-trimester women had SF levels less than 15 μg/L. Approximately 21% of third-trimester and 4% of first-trimester women had anemia (Hb iron-deficient nonanemic (SF iron-deficiency anemia (SF iron deficiency (sTfr >8.5 mg/L). The median body iron stores were 8.1 mg/kg among first-trimester women, but only 3.6 mg/kg among third-trimester women. SF levels were significantly positively associated with age and education level, and were higher among nulliparous women and lower among North-African women. sTfr concentrations were significantly negatively associated with age and were lower among smokers, nulliparous women, and women who planned their pregnancy. Despite the fact that two thirds of Belgian pregnant women took iron-containing supplements, iron deficiency and iron-deficiency anemia were frequent in third-trimester women. The World Health Organization regards this as a moderate public health problem. National iron supplementation guidelines are needed in Belgium to optimize iron status during pregnancy.

  3. Iron-oxo clusters biomineralizing on protein surfaces: Structural analysis of Halobacterium salinarum DpsA in its low- and high-iron states

    OpenAIRE

    Zeth, Kornelius; Offermann, Stefanie; Essen, Lars-Oliver; Oesterhelt, Dieter

    2004-01-01

    The crystal structure of the Dps-like (Dps, DNA-protecting protein during starvation) ferritin protein DpsA from the halophile Halobacterium salinarum was determined with low endogenous iron content at 1.6-Å resolution. The mechanism of iron uptake and storage was analyzed in this noncanonical ferritin by three high-resolution structures at successively increasing iron contents. In the high-iron state of the DpsA protein, up to 110 iron atoms were localized in the dodecameric protein complex....

  4. Determination of iron, copper and aluminium by gas-liquid chromatography.

    Science.gov (United States)

    Moshier, R W; Schwarberg, J E

    1966-03-01

    Gas chromatography has been utilised in the analysis of two National Bureau of Standard alloys for quantitative determination of aluminium, iron and copper. In the analysis of N.B.S. 162a the relative mean errors were 3.13% for aluminium, 2.06% for iron and -1.72% for copper and for N.B.S. 164a the relative mean errors were -1.39%, -0.19% and -0.89% for aluminium, iron and copper, respectively. The procedure for analysis involves solution of the alloy, conversion of the metal ions to trifluoroacetylacetonates by solvent extraction and, finally, complete separation of the metal chelates and quantitative determination by gas chromatography using a column containing Gas Pack F coated with Tissuemat E, a polyethylene wax. Other metals present in the N.B.S. samples did not interfere with the determination of aluminium, iron and copper.

  5. Catechol versus bisphosphonate ligand exchange at the surface of iron oxide nanoparticles: towards multi-functionalization

    Science.gov (United States)

    Guénin, Erwann; Lalatonne, Yoann; Bolley, Julie; Milosevic, Irena; Platas-Iglesias, Carlos; Motte, Laurence

    2014-11-01

    We report an investigation of the ligand exchange at the surface of iron oxide nanoparticles in water. For this purpose we compared two strong chelating agents on the iron oxide surface containing catechol and bisphosphonate moieties. Interactions between the coating agents (catechol/bisphosphonate) and the nanoparticle's surface were studied by FTIR and DFT calculations. Ligand exchange experiments were performed using sonication and the exchange yield was characterized by FTIR and EDX. This methodology allowed introducing bisphosphonates with various functionalities (alkyne or biotin) permitting multi-functionalization.

  6. Metallurgical investigations of dry sliding surface layer in phosphorous iron/steel friction pairs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Surface layer behaviors of composition concentration and micro-hardness were inves-tigated on phosphorous cast irons after dry sliding. The experimental results indicate that thehardness and chemical composition unevenly distribute in the surface layer. The sliding conditionand microstructure of the pin specimen have greatly effects on the distributions.

  7. Oscillatory behavior of the magnetic moments of gold-covered iron surfaces

    NARCIS (Netherlands)

    Fang, C.M.; Groot, R.A. de; Bischoff, M.M.J.; Kempen, H. van

    1998-01-01

    Local magnetic moments at iron (001) surfaces have been studied by electronic structure calculations employing the slab geometry up to 17 layers. Whereas the clean Fe(001) surface shows oscillations in the local magnetic moments, no oscillations were observed in the case of coverage by a monolayer

  8. Gold nanostar - iron oxide core-shell nanostructures: synthesis, characterization, and demonstrated surface-enhanced Raman scattering properties

    Energy Technology Data Exchange (ETDEWEB)

    Esenturk, Emren Nalbant, E-mail: emren@metu.edu.tr [Middle East Technical University, Department of Chemistry (Turkey); Hight Walker, Angela R. [National Institute of Standards and Technology, Radiation and Biomolecular Physics Division, Physical Measurement Laboratory (United States)

    2013-01-15

    Iron oxide-coated gold nanostars are produced by first synthesizing gold nanostars (ca 150 nm), then introducing a polyvinylpyrollidone coating followed by reducing iron(II) and iron(III) salts on the nanoparticle (NP) surface. Morphological and chemical composition characterizations of these composite nanomaterials were performed via field-emission transmission electron microscopy/energy dispersive spectroscopy studies. The analysis revealed that the majority of the NPs had coating of approximately 1-5 nm thicknesses. The crystal structure of the coating on gold nanostars was determined to be {alpha}-Fe{sub 2}O{sub 3} with X-ray diffraction analysis. X-ray photoelectron spectroscopy confirmed that the coating is Fe{sub 2}O{sub 3}. The magnetic property studies via superconducting quantum interference device magnetometer revealed an antiferromagnetic behavior of the magnetic coating, verifying the existence of antiferromagnetic {alpha}-Fe{sub 2}O{sub 3} layer on gold nanostars. Surface-enhanced Raman scattering (SERS) spectroscopy performed with crystal violet as the probe molecule confirms continued strong SERS activity for gold nanostars after the iron oxide coating. Having both magnetic and plasmonic properties in one NP system makes these particles suitable for various bio-analytical applications such as biomolecule separation, sensing and magnetic imaging.

  9. Rapid collection of iron hydroxide for determination of Th isotopes in seawater.

    Science.gov (United States)

    Okubo, Ayako; Obata, Hajime; Magara, Masaaki; Kimura, Takaumi; Ogawa, Hiroshi

    2013-12-04

    This work introduces a novel method of recovery of iron hydroxide using a DIAION CR-20 chelating resin column to determine Th isotopes in seawater with a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). Thorium isotopes in seawater were co-precipitated with iron hydroxide, and this precipitate was sent to chelating resin column. Ferric ions in the iron hydroxide were bonded to functional groups of the chelating resin directly, resulting in a pH increase of the effluent by release of hydroxide ion from the iron hydroxide. The co-precipitated thorium isotopes were quantitatively collected within the column, which indicated that thorium was retained on the iron hydroxide remaining on the chelating column. The chelating column quantitatively collected (232)Th with iron hydroxide in seawater at flow rates of 20-25 mL min(-1). Based on this flow rate, a 5 L sample was processed within 3-4 h. The >20 h aging of iron hydroxide tends to reduce the recovery of (232)Th. The rapid collection method was successfully applied to the determination of (230)Th and (232)Th in open-ocean seawater samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Advances on surface structural determination by LEED

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Edmar A; De Carvalho, Vagner E [Departamento de Fisica, ICEX, Universidade Federal de Minas Gerais, 31270-090, Belo Horizonte, MG (Brazil); De Castilho, Caio M C, E-mail: edmar@fisica.ufmg.br [Grupo de Fisica de SuperfIcies e Materiais, Instituto de Fisica and Instituto Nacional de Ciencia e Tecnologia em Energia e Ambiente (CIENAM)INCT-E and A, Universidade Federal da Bahia, Campus Universitario da Federacao, 40170-115, Salvador, BA (Brazil)

    2011-08-03

    In the last 40 years, low energy electron diffraction (LEED) has proved to be the most reliable quantitative technique for surface structural determination. In this review, recent developments related to the theory that gives support to LEED structural determination are discussed under a critical analysis of the main theoretical approximation-the muffin-tin calculation. The search methodologies aimed at identifying the best matches between theoretical and experimental intensity versus voltage curves are also considered, with the most recent procedures being reviewed in detail. (topical review)

  11. Advances on surface structural determination by LEED.

    Science.gov (United States)

    Soares, Edmar A; de Castilho, Caio M C; de Carvalho, Vagner E

    2011-08-03

    In the last 40 years, low energy electron diffraction (LEED) has proved to be the most reliable quantitative technique for surface structural determination. In this review, recent developments related to the theory that gives support to LEED structural determination are discussed under a critical analysis of the main theoretical approximation-the muffin-tin calculation. The search methodologies aimed at identifying the best matches between theoretical and experimental intensity versus voltage curves are also considered, with the most recent procedures being reviewed in detail.

  12. Quantitative proteomic view on secreted, cell surface-associated, and cytoplasmic proteins of the methicillin-resistant human pathogen Staphylococcus aureus under iron-limited conditions.

    Science.gov (United States)

    Hempel, Kristina; Herbst, Florian-Alexander; Moche, Martin; Hecker, Michael; Becher, Dörte

    2011-04-01

    Staphylococcus aureus is capable of colonizing and infecting humans by its arsenal of surface-exposed and secreted proteins. Iron-limited conditions in mammalian body fluids serve as a major environmental signal to bacteria to express virulence determinants. Here we present a comprehensive, gel-free, and GeLC-MS/MS-based quantitative proteome profiling of S. aureus under this infection-relevant situation. (14)N(15)N metabolic labeling and three complementing approaches were combined for relative quantitative analyses of surface-associated proteins. The surface-exposed and secreted proteome profiling approaches comprise trypsin shaving, biotinylation, and precipitation of the supernatant. By analysis of the outer subproteomic and cytoplasmic protein fraction, 1210 proteins could be identified including 221 surface-associated proteins. Thus, access was enabled to 70% of the predicted cell wall-associated proteins, 80% of the predicted sortase substrates, two/thirds of lipoproteins and more than 50% of secreted and cytoplasmic proteins. For iron-deficiency, 158 surface-associated proteins were quantified. Twenty-nine proteins were found in altered amounts showing particularly surface-exposed proteins strongly induced, such as the iron-regulated surface determinant proteins IsdA, IsdB, IsdC and IsdD as well as lipid-anchored iron compound-binding proteins. The work presents a crucial subject for understanding S. aureus pathophysiology by the use of methods that allow quantitative surface proteome profiling.

  13. Spectrophotometric Determination of Iron(III) after Separation by Adsorption of its Pyrrolidinedithiocarbamate on Nephthalene

    OpenAIRE

    Masatada Satake; Singh, H. B.

    1982-01-01

    A method for the spectrophotometric determination of trace amounts of iron(III) after adsorption of its pyrrolidindeithiocarbamate on naphthalene is presented. Iron(III) forms a water-insoluble chelate with ammonium pyrrolidinedithiocarbamate in the pH range 2.9-6.6. This chelate is quantitatively adsorbed onto mycrocrystalline naphthalene at room temperature. The effects of variablesm, such as pH, amount of reagent and napthalene, digestion and shaking time, and diverse ions, have been exami...

  14. Molecular dynamics simulations of dodecylamine adsorption on iron surfaces in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Tang Yongming, E-mail: tangym@njut.edu.c [School of Science, Nanjing University of Technology, Nanjing 210009 (China); Yao Lala; Kong Chunmei; Yang Wenzhong [School of Science, Nanjing University of Technology, Nanjing 210009 (China); Chen Yizhong [School of Environmental and Safety Engineering, Jiangsu Polytechnic University, Changzhou 213164 (China)

    2011-05-15

    Research highlights: {yields} MD simulations results of the adsorption of DDA on iron surfaces are strongly related to the simulation conditions. {yields} DDAH is main adsorption form in strong acidic solution. {yields} Chloride ions play an important role on the adsorption of DDA in weak acidic solution. - Abstract: Molecular dynamics (MD) simulations have been used to study the adsorption of dodecylamine (DDA) on iron surfaces in aqueous solution in this paper. In strong acidic solution the protonated form of DDA, DDAH, can adsorb on the iron surface preferentially, while in weak acidic solution containing chloride ions the adsorption of DDA and DDAH forms can occur simultaneously. Different results were obtained when different simulation factors were considered. In order to obtain the correct results, a model close to the realistic inhibition system was fabricated.

  15. Climatically sensitive transfer of iron to maritime Antarctic ecosystems by surface runoff

    Science.gov (United States)

    Hodson, Andy; Nowak, Aga; Sabacka, Marie; Jungblut, Anne; Navarro, Francisco; Pearce, David; Ávila-Jiménez, María Luisa; Convey, Peter; Vieira, Gonçalo

    2017-01-01

    Iron supplied by glacial weathering results in pronounced hotspots of biological production in an otherwise iron-limited Southern Ocean Ecosystem. However, glacial iron inputs are thought to be dominated by icebergs. Here we show that surface runoff from three island groups of the maritime Antarctic exports more filterable (iron (6–81 kg km−2 a−1) than icebergs (0.0–1.2 kg km−2 a−1). Glacier-fed streams also export more acid-soluble iron (27.0–18,500 kg km−2 a−1) associated with suspended sediment than icebergs (0–241 kg km−2 a−1). Significant fluxes of filterable and sediment-derived iron (1–10 Gg a−1 and 100–1,000 Gg a−1, respectively) are therefore likely to be delivered by runoff from the Antarctic continent. Although estuarine removal processes will greatly reduce their availability to coastal ecosystems, our results clearly indicate that riverine iron fluxes need to be accounted for as the volume of Antarctic melt increases in response to 21st century climate change. PMID:28198359

  16. Surface iron inhibits quartz-induced cytotoxic and inflammatory responses in alveolar macrophages.

    Science.gov (United States)

    Ghiazza, Mara; Scherbart, Agnes M; Fenoglio, Ivana; Grendene, Francesca; Turci, Francesco; Martra, Gianmario; Albrecht, Catrin; Schins, Roel P F; Fubini, Bice

    2011-01-14

    The mechanism of enhancement/inhibition of quartz toxicity induced by iron is still unclear. Here the amount of iron on a fibrogenic quartz (Qz) was increased by wet impregnation (Fe(NO(3))(3) 0.67 and 6.7 wt %). X-ray diffraction (XRD), XRF diffuse reflectance, UV-vis, and infrared (IR) spectroscopies revealed dispersed ferric ions, and hematite aggregates at the higher loading. Surface features relevant to pathogenicity and cell responses were compared not only to the original quartz but also to reference quartz DQ12. Surface charge (ζ-potential) was more negative on the original and low-loaded specimen than on the high-loaded one. DQ12 had a less negative ζ-potential than Qz, ascribed to the absence of aluminium present in Qz (1.7 wt %). All quartz specimens were able to generate HO(•) radicals, iron-loaded samples being more reactive than original quartz. Iron deposition inhibited the rupture of a C-H bond. All quartzes were phagocytized by alveolar macrophages (AMΦ cell line NR8383) to the same extent, irrespective of their surface state. Conversely, iron loading increased AMΦ viability (evaluated by cytotoxicity and induction of apoptosis). Qz was found to be much less cytotoxic than DQ12. The induction of oxidative stress and inflammatory responses (evaluated by HO-1 mRNA expression and TNF-α mRNA and protein expression) revealed a reduction in inflammogenicity upon iron loading and a more inflammogenic potency of DQ12 ascribed to undissociated SiOH interacting via H-bonding with cell membrane components. The results suggest that besides aluminium also iron at the quartz surface may have an inhibitory effect on adverse health responses.

  17. Continuous flow analysis method for determination of soluble iron and aluminium in ice cores.

    Science.gov (United States)

    Spolaor, A; Vallelonga, P; Gabrieli, J; Roman, M; Barbante, C

    2013-01-01

    Iron and aluminium are the two most abundant metals on the Earth's crust, but they display quite different biogeochemical properties. While iron is essential to many biological processes, aluminium has not been found to have any biological function at all. In environmental studies, iron has been studied in detail for its limiting role in the bioproductivity of high nutrient, low carbon oceanic zones, while aluminium is routinely used as a reference of crustal contributions to atmospheric deposition archives including peat bogs, lacustrine and marine sediments and ice sheets and glaciers. We report here the development of a flow injection analysis technique, which has been optimised for the simultaneous determination of soluble iron and aluminium in polar ice cores. Iron was determined by its catalytic role in the reduction of N,N-dimethyl-p-phenylenediamene (DPD) to a semiquinonic form (DPDQ) and subsequent absorption spectroscopy at 514 nm. Aluminium was determined by spectroscopic analysis of an aluminium-lumogallion complex that exhibits fluorescence at 560 nm. These techniques have been applied to a section of Greenland ice dated to 1729-1733 AD and indicate that volcanism is a source of highly soluble aluminium and iron.

  18. Behavior Of Austempered Ductile Irons (ADI) Subjected To Laser Surface Melting

    Science.gov (United States)

    Jones, D. L.; Fagoaga, I.; Liceaga, J. F.; Sanz Justes, Pedro; Jasnowski, Kazie S.

    1989-03-01

    The near surface microstructure of 3 austempered ductile irons has been modified using laser surface melting (LSM). A white cast iron layer was produced to depths of up to 500 microns. The microstructure of this region varied depending upon the parameters used. A heat affected zone (HAZ) appeared at an abrupt transition between the LSM zone and the substrate. The size of the HAZ, which varied between 20 and 200 microns was predominately affected by the pass velocity in the range of energies used. The hardness profiles showed large variations in the Haz probably due to varing tempering effects from the subsequent passes.

  19. The mechanism of changes in the surface layer of grey cast iron automotive brake disc

    OpenAIRE

    Adam Polak; Janusz Grzybek

    2005-01-01

    The aim of the study was to create a model, describing the run of tribological processes in the surface layer of grey cast iron automotive brake discs. Grey cast iron discs mating with non-asbestos organic brake pads were chosen for the investigations, as the most widely used materials in car brakes. Samples for surface analysis were prepared from disc operating in stand and road conditions. Stand tests were pin-on-disc kind. Operating parameters for the stand tests were chosen on the basis o...

  20. Iron and contact with host cells induce expression of adhesins on surface of Trichomonas vaginalis.

    Science.gov (United States)

    Garcia, Ana F; Chang, Te-Hung; Benchimol, Marlene; Klumpp, David Jichael; Lehker, Michael W; Alderete, John F

    2003-03-01

    The proteins AP65, AP51, AP33 and AP23 synthesized by Trichomonas vaginalis organisms in high iron play a role in adherence. Multigene families encode enzymes of the hydrogenosome organelles, which have identity to adhesins. This fact raises questions regarding the compartmentalization of the proteins outside the organelle and about the interactions of adhesins with host cells. Data here demonstrate the presence of the proteins outside the organelle under high-iron conditions. Fluorescence and immuno-cytochemical experiments show that high-iron-grown organisms coexpressed adhesins on the surface and intracellularly in contrast with low-iron parasites. Furthermore, the AP65 epitopes seen by rabbit anti-AP65 serum that blocks adherence and detects surface proteins were identified, and a mAb reacting to those epitopes recognized the trichomonal surface. Two-dimensional electrophoresis and immunoblot of adhesins from surface-labelled parasites provided evidence that all members of the multigene family were co-ordinately expressed and placed on the trichomonal surface. Similar two-dimensional analysis of proteins from purified hydrogenosomes obtained from iodinated trichomonads confirmed the specific surface labelling of proteins. Contact of trichomonads with vaginal epithelial cells increased the amount of surface-expressed adhesins. Moreover, we found a direct relationship between the levels of adherence and amount of adhesins bound to immortalized vaginal and ureter epithelial cells, further reinforcing specific associations. Finally, trichomonads of MR100, a drug-resistant isolate absent in hydrogenosome proteins and adhesins, were non-adherent. Overall, the results confirm an important role for iron and contact in the surface expression of adhesins of T. vaginalis organisms.

  1. A Kinetic Spectrophotometric Method for the Determination of Iron (Ⅲ) in Water Samples

    Institute of Scientific and Technical Information of China (English)

    JI Hongwei; XU Jian; XIN Huizhen; YANG Xiaoman

    2008-01-01

    A new kinetic spectrophotometric method has been developed for the determination of iron (Ⅲ). The method is based on the catalytic effect of iron (Ⅲ) on the oxidation of weak acid brilliant blue dye (RAWL) by KIO4 in acid medium. The advantages of the proposed method are that it is sensitive, accurate, rapid, inexpensive, can be operated under room temperature and has a large determination concentration range compared to other techniques. The obtained optimum conditions are: pH 3.15, RAWL (200 mgL-1) 5.00mL, Potassium periodate solution (0.01 molL-1) 0.30mL, phenanthroline (0.02molL-1) 1.00mL, reaction temperature 25℃ and reaction time 7 miu. With this method iron could quantitively be determined in the range 0.00-0.02 mgL-1, the detection limit being 4.10×10-10mL-1. The relative standard deviations (RSD) in five replicate determinations for 3 μgL-1 and 5μgL-1 iron (Ⅲ) are 3.1% and 1.9%, respectively. The method has been applied to the determination of iron (Ⅲ) in tap water samples and seawater samples (from the South China Sea), the recovery rates being 98.0% and 100.5%, respectively.

  2. The determination of aluminum, copper, iron, and lead in glycol formulations by atomic absorption spectroscopy

    Science.gov (United States)

    1977-01-01

    Initial screening tests and the results obtained in developing procedures to determine Al, Cu, Fe, and Pb in glycol formulations are described. Atomic absorption completion was selected for Cu, Fe and Pb, and after comparison with emission spectroscopy, was selected for Al also. Before completion, carbon, iron, and lead are extracted with diethyl dithio carbamate (DDC) into methyl isobutyl ketone (MIBK). Aluminum was also extracted into MIBK using 8-hydroxyquinoline as a chelating agent. As little as 0.02 mg/l carbon and 0.06 mg/l lead or iron may be determined in glycol formulations. As little as 0.3 mg/l aluminum may be determined.

  3. Tumour Cell Labelling by Magnetic Nanoparticles with Determination of Intracellular Iron Content and Spatial Distribution of the Intracellular Iron

    Directory of Open Access Journals (Sweden)

    Alfred Cuschieri

    2013-04-01

    Full Text Available Magnetically labelled cells are used for in vivo cell tracking by MRI, used for the clinical translation of cell-base therapies. Studies involving magnetic labelled cells may include separation of labelled cells, targeted delivery and controlled release of drugs, contrast enhanced MRI and magnetic hyperthermia for the in situ ablation of tumours. Dextran-coated super-paramagnetic iron oxide (SPIO ferumoxides are used clinically as an MR contrast agents primarily for hepatic imaging. The material is also widely used for in vitro cell labelling, as are other SPIO-based particles. Our results on the uptake by human cancer cell lines of ferumoxides indicate that electroporation in the presence of protamine sulphate (PS results in rapid high uptake of SPIO nanoparticles (SPIONs by parenchymal tumour cells without significant impairment of cell viability. Quantitative determination of cellular iron uptake performed by colorimetric assay is in agreement with data from the literature. These results on intracellular iron content together with the intracellular distribution of SPIONs by magnetic force microscopy (MFM following in vitro uptake by parenchymal tumour cells confirm the potential of this technique for clinical tumour cell detection and destruction.

  4. Iron phosphate glasses: Structure determination and radiation tolerance

    Science.gov (United States)

    Jolley, Kenny; Smith, Roger

    2016-05-01

    Iron phosphate glass (IPG) has gained recent interest for use in encapsulating radioactive waste for long term storage. In this work, we investigate 5 different compositions of iron phosphate glass. We consider amorphous structures of 3 known crystalline phases: Fe2+ Fe23+ (P2O7)2, Fe43 + (P2O7)3 and Fe3+(PO3)3, and structures of IPG (40 mol% Fe2O3 and 60 mol% P2O5), with 4% and 17% Fe2+ ion concentrations. Using constant volume molecular dynamics (MD), we quench a set of structures for each glass composition, to find the optimal density structure. We found that the lowest energy structures of IPG with 4% and 17% concentration of Fe2+, have a density of 3.25 and 3.28 g/cm3 respectively. This is slightly higher than the experimentally measured values of 2.9 and 2.95 g/cm3 respectively. We also estimate an upper and lower bound on the melting temperatures of each glass, then for each glass, we simulate radiation damage cascades at 4 keV. The cascade structures can be in the form of either a concentrated thermal spike or more diffuse with sub-cascade branching. We found that the glass compositions with a higher Fe/P atomic ratio, contained a greater number of displacements after the cascade. We also found that the IPG with 4% Fe2+, contained slightly fewer displacements than the IPG with 17% Fe2+. This is consistent with our previous work, which showed that the threshold displacement energies are lower for glasses with a lower Fe2+ content. In all the simulations, many PO4 polyhedra are destroyed during the early stages of irradiation, but recover strongly over a time scale of picoseconds, leaving very few over or under co-ordinated P atoms at the end of the ballistic phase. This is in contrast to recent work in apatite. The strong recovery indicates that phosphate glasses with a low Fe2+ content could be good materials for waste encapsulation.

  5. Reduction of Nitroaromatic Compounds on the Surface of Metallic Iron: Quantum Chemical Study

    Directory of Open Access Journals (Sweden)

    Jerzy Leszczynski

    2002-07-01

    Full Text Available Abstract: The initial reduction steps of nitroaromatic compounds on the surface of metallic iron have been studied theoretically using nitrobenzene (NB as a representative of nitroaromatic compounds. The quantum chemical cluster approximation within the semiempirical Neglect of Diatomic Differential Overlap for Metal Compounds method was applied to model the Fe(110 crystallographic surface, taken as a representative reactive surface for granular iron. This surface was modeled as a 39-atom two-layer metal cluster with rigid geometry. The associative and dissociative adsorption of nitrobenzene was considered. Based on our quantum chemical analysis, we suggest that the direct electron donation from the metal surface into the π* orbital of NB is a decisive factor responsible for subsequent transformation of the nitro group. Molecularly adsorbed NB interacts with metal iron exclusively through nitro moiety oxygens which occupy tri-coordinated positions on surface The charge transfer from metal to NB of approximately 2 atomic units destablizes the nitro group. As a result, the first dissociation of the N-O bond goes through a relatively low activation barrier. The adsorbed nitrosobenzene is predicted to be a stable surface species, though still quiet labile.

  6. Sulfur and iron speciation in surface sediments along the northwestern margin of the Black Sea

    NARCIS (Netherlands)

    Wijsman, J.W.M.; Middelburg, J.J.; Herman, P.M.J.; Bottcher, M.E.; Heip, C.H.R.

    2001-01-01

    The speciation of sedimentary sulfur (pyrite, acid volatile sulfides (AVS), S-0 H2S, and sulfate) was analyzed in surface sediments recovered at different water depths from the northwestern margin of the Black Sea. Additionally, dissolved and dithionite-extractable iron were quantified, and the sulf

  7. Self Assembly of Biogenic Surfactants at Mineral Surfaces and Their Effect on Biological Iron Acquisition

    Science.gov (United States)

    Kraemer, S. M.

    2005-12-01

    Microorganisms exude biogenic surfactants to modify the physical and chemical properties of mineral-water interfaces. Surfactants with negatively charged hydrophilic head groups interact strongly with oppositely charged mineral surfaces such as iron or aluminum oxides. Surfactant self assembly at mineral surfaces can result in the formation of admicelles that have a significant effect on the surface charge and hydrophobicity. These effects are exploited by microorganisms to facilitate attachment to mineral surfaces. Similarly, plants exude surfactants into the rhizosphere and change the surface tension and flow of soil water. Other surface active compounds that are typically found in soils and surface waters are humic substances and fatty acids that are produced by degradation of biomass. In general, surface active compounds are ubiquitous in natural systems. In this study we investigated how surfactants influence bio-mineral interactions using the example of siderophore promoted iron acquisition. Siderophore promoted iron acquisition involves the adsorption of a biogenic iron specific ligand (i.e. the siderophore) to iron oxides and the subsequent siderophore promoted iron oxide dissolution. The hypothesis of this project is that the modification of the iron oxide surface charge and hydrophobicity by adsorbed surfactants will have an important effect on siderophore adsorption and dissolution kinetics. We approached this subject by investigating the adsorption of a natural surfactant (rhamnolipids: RhL) and the synthetic surfactant (sodium dodecyl sulfate: SDS) on goethite (α-FeOOH, a common pedogenic iron oxide) and observing the effect of surfactant self assembly on the properties of the mineral water interface. We observed fast adsorption kinetics at pH 3 and slow adsorption at pH 6. The adsorbed surfactants reversed the surface potential of goethite (as evidenced by electrophoretic mobility measurements) at soluble surfactant concentrations below 10 μM (SDS

  8. Ascorbate-Promoted Surface Iron Cycle for Efficient Heterogeneous Fenton Alachlor Degradation with Hematite Nanocrystals.

    Science.gov (United States)

    Huang, Xiaopeng; Hou, Xiaojing; Jia, Falong; Song, Fahui; Zhao, Jincai; Zhang, Lizhi

    2017-03-15

    This study reports the H2O2 activation with different hematite nanocrystals and ascorbate ions for the herbicide alachlor degradation at pH 5. We found that hematite nanoplates (HNPs) exposed with {001} facets exhibited better catalytic performance than hematite nanocubes (HNCs) exposed with {012} facets, which was attributed to the formation of inner-sphere iron-ascorbate complexes on the hematite facets. The 3-fold undercoordination Fe cations of {001} facet favors the formation of inner-sphere iron-ascorbate complexes, while the 5-fold undercoordination Fe cations of {012} facet has stereo-hindrance effect, disfavoring the complex formation. The surface area normalized alachlor degradation rate constant (23.3 × 10(-4) min(-1) L m(-2)) of HNPs-ascorbate Fenton system was about 2.6 times that (9.1 × 10(-4) min(-1) L m(-2)) of HNCs-ascorbate counterpart. Meanwhile, the 89.0% of dechlorination and 30.0% of denitrification in the HNPs-ascorbate Fenton system were also significantly higher than those (60.9% and 13.1%) of the HNCs-ascorbate one. More importantly, the reductive dissolution of hematite by ascorbate was strongly coupled with the subsequent H2O2 decomposition by surface bound ferrous ions through surface iron cycle on the hematite facets in the hematite-ascorbate Fenton systems. This coupling could significantly inhibit the conversion of surface bound ferrous ions to dissolved ones, and thus account for the stability of hematite nanocrystals. This work sheds light on the internal relationship between iron geochemical cycling and contaminants degradation, and also inspires us to utilize surface iron cycle of widely existent hematite for environmental remediation.

  9. Photoemission from real iron surfaces and its relationship to light penetration of the overlayer

    Science.gov (United States)

    Momose, Yoshihiro; Suzuki, Daisuke; Sakurai, Takao; Nakayama, Keiji

    2015-02-01

    We report the photoemission from real iron surfaces at elevated temperatures, called thermally assisted photoemission (TAPE), and its relationship to the X-ray photoelectron spectroscopy (XPS) results. TAPE measurements were carried out using a Geiger counter under a gaseous atmosphere of He containing 1 % isobutane vapor at normal atmospheric pressure. A sample was initially heated to temperatures ranging from 25 to 353 °C under light irradiation at a certain wavelength of 200, 210, 220, and 230 nm, and then, wavelength was scanned from 300 to 170 nm at the final temperature. The values of a constant related to electron photoemission probability, αA, where A is identical with the Richardson constant, and photothreshold (photoelectric work function), ϕ, were obtained from a plot of the square root of the electron photoemission intensity against the photon energy; the αA values increased with temperature, and the ϕ values also increased with temperature. From the Arrhenius plot, the αA was found to have an activation energy Δ E αA = 0.096 eV. The activation energies of the surface oxygen component ratio Z = O2-/(OH + O2-) and the surface elemental composition ratio X = Fe/(O + N + C + Fe) obtained from the XPS data were also determined from their Arrhenius plots: Δ E Z = 0.113 eV and Δ E X = 0.039 eV, respectively. From a close resemblance between the latter activation energies and those of the Δ E αA and the Δ E a = 0.112-0.040 eV for the quantum yields (Momose et al. in Appl Phys A. doi: 10.1007/s00339-014-8589-7, 2014), it was found that the increase in the intensity of the TAPE with temperature was strongly associated with the increase in the values of Z and X with temperature. It was therefore concluded that the ability of the surface overlayer to pass the incident light became a rate-determining step to start the photoemission, which was decisively controlled by the temperature-dependent surface oxygen components and surface compositions. The

  10. Determining surface wave arrival angle anomalies

    Science.gov (United States)

    Larson, Erik W. F.; Ekström, Göran

    2002-06-01

    A new method for measuring arrival angles of teleseismic Love and Rayleigh waves is developed. The new method utilizes estimates of surface wave dispersion to create a phase-matched filter to isolate the Love or Rayleigh wave in three-component recordings. The polarization of the filtered wave group is determined in the time domain by application of a variation of the complex polarization method of Vidale [1986]. Orientation, linearity, and ellipticity of particle motion are estimated in several frequency bands to determine the frequency-dependent polarization. The method employs an iterative scheme, by which a predicted Love wave, based on the estimated dispersion and polarization, is subtracted from the three-component data prior to the estimation of Rayleigh wave polarization, and vice versa. The method is applied to an extensive set of Global Seismographic Network data covering the years 1989-1998. Between 4244 and 15,075 measurements are collected for fundamental mode Love and Rayleigh waves at nine different periods (37 to 150 s). Measurement uncertainties are estimated using the statistics of observations for pairwise similar paths and are generally of the order of 15-50% of the total signal, depending on the period and the wave type. Large and azimuthally invariant angle anomalies are documented for several stations and are consistent with misorientation of the horizontal seismometers. Two schemes are employed to determine the misorientations: (1) an azimuthally weighted average at each station, and (2) a joint inversion for seismometer misorientation and globally heterogeneous phase velocities. The determined corrections are robust and correlate well with those reported in earlier studies. Azimuthally varying arrival angle anomalies are shown to agree qualitatively with predictions of wave refraction calculated for recent phase velocity maps, which explain up to 30% of the variance in the new measurements.

  11. Determination of blood counts at sideropenic anemia, and monitoring depending on the outcome rate of iron absorption

    OpenAIRE

    PANOCHOVÁ, Daniela

    2011-01-01

    Sideropenic anemia (iron deficiency anemia) is the most common anemia all over the world. The cause of this anemia type is lack of iron. This thesis deals with the determination of blood picture treatment results and iron absorption in patients with sideropenic anemia. In the practical part, the methods of blood picture determination as well as iron determination and the resorption curve are described. The blood picture is provided at the Clinical Haematology Ward of the České Budějovice Hosp...

  12. Determination of iron in natural and mineral waters by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    ROLANDAS KAZLAUSKAS

    2004-05-01

    Full Text Available Simple methods for the determination of Fe in natural and mineral waters by flame atomic absorption spectrometry (AAS are suggested. The results of the investigation of selectivity of the proposed AAS method proved that this procedure is not affected by high concentrations of other metals. The calibration graph for iron was linear at levels near the detection limit up to at least 0.10 mg ml-1. For the determination of microamounts of iron in mineral waters, an extraction AAS technique was developed. Iron was retained as Fe-8-oxyquinoline complex and extracted into chloroform. The optimal conditions for the extraction of the iron complex were determined. The AAS method was applied to the determination of Fe in mineral waters and natural waters from different areas of Lithuania. The accuracy of the developed method was sufficient and evaluated in comparison with a photometric method. The obtained results demonstrated that the procedure could be successfully applied for the analysis of water samples with satisfactory accuracy.

  13. Determination of Total Iron as Fe(II) in Multivitamins, Haematinics ...

    African Journals Online (AJOL)

    The determination of total iron in pharmaceutical products and natural waters as Fe(II) ... as a [Fe(phen)32+] complex at 515 nm with a UV/Vis spectrophotometer. The linear range of the system is between 1 and 60 mg/l with a detection limit of ...

  14. A community-wide intercomparison exercise for the determination of dissolved iron in seawater

    NARCIS (Netherlands)

    Bowie, A.R.; Achterberg, E.P.; Croot, P.l.; de Baar, H.J.W.; Laan, P.; Moffett, J.W; Ussher, S.; Worsfold, P.J.

    2006-01-01

    The first large-scale international intercomparison of analytical methods for the determination of dissolved iron in seawater was carried out between October 2000 and December 2002. The exercise was conducted as a rigorously "blind" comparison of 7 analytical techniques by 24 international laborator

  15. Iron oxide and hydroxide precipitation from ferrous solutions and its relevance to Martian surface mineralogy

    Science.gov (United States)

    Posey-Dowty, J.; Moskowitz, B.; Crerar, D.; Hargraves, R.; Tanenbaum, L.

    1986-01-01

    Experiments were performed to examine if the ubiquitousness of a weak magnetic component in all Martian surface fines tested with the Viking Landers can be attributed to ferric iron precipitation in aqueous solution under oxidizing conditions at neutral pH. Ferrous solutions were mixed in deionized water and various minerals were added to separate liquid samples. The iron-bearing additives included hematite, goethite, magnetite, maghemite, lepidocrocite and potassium bromide blank at varying concentrations. IR spectroscopic scans were made to identify any precipitates resulting from bubbling oxygen throughout the solutions; the magnetic properties of the precipitates were also examined. The data indicated that the lepidocrocite may have been preferentially precipitated, then aged to maghemite. The process would account for the presumed thin residue of maghemite on the present Martian surface, long after abundant liquid water on the Martian surface vanished.

  16. The surface of iron molybdate catalysts used for the selective oxidation of methanol

    Science.gov (United States)

    Yeo, Benjamin R.; Pudge, Geoffrey J. F.; Bugler, Keith G.; Rushby, Alice V.; Kondrat, Simon; Bartley, Jonathan; Golunski, Stanislaw; Taylor, Stuart H.; Gibson, Emma; Wells, Peter. P.; Brookes, Catherine; Bowker, Michael; Hutchings, Graham J.

    2016-06-01

    The oxidation of methanol to formaldehyde is a major chemical process carried out catalytically and iron molybdate is one of the major catalysts for this process. In this paper we explore the nature of the active and selective surfaces of iron molybdate catalysts and show that the effective catalysts comprise molybdenum rich surfaces. We conclude that it is therefore important to maximise the surface area of these active catalysts and to this end we have studied catalysts made using a new physical grinding method with oxalic acid. For super-stoichiometric materials (Fe:Mo = 1:2.2) the reaction data show that physical mixing produces effective catalysts, possibly offering an improvement over the conventional co-precipitation method.

  17. Surfaces of a colloidal iron nanoparticle in its chemical environment: a DFT description.

    Science.gov (United States)

    Fischer, Guntram; Poteau, Romuald; Lachaize, Sébastien; Gerber, Iann C

    2014-10-01

    Describing and understanding surface chemistry on the atomic scale is of primary importance in predicting and rationalize nanoparticle morphology as well as their physical and chemical properties. Here we present the results of comprehensive density functional theory studies on the adsorption of several small organic species, representing the major species (H2, Cl2, HCl, NH3, NH4Cl, and CH3COOH), present in the reaction medium during colloidal iron nanoparticle synthesis on various low-index iron surface models, namely, (100), (110), (111), (211), and (310). All of the tested ligands strongly interact with the proposed surfaces. Surface energies are calculated and ligand effects on the morphologies are presented, including temperature effects, based on a thermodynamic approach combined with the Wulff construction scheme. The importance of taking into account vibrational contributions during the calculation of surface energies after adsorption is clearly demonstrated. More importantly, we find that thermodynamic ligand effects can be ruled out as the unique driving force in the formation of recently experimentally observed iron cubic nanoparticles.

  18. Distribution of Organic Matter, Iron, Mangenese in Surface Sediments in the Nansha Islands Sea Area, South China Sea

    Institute of Scientific and Technical Information of China (English)

    Zhou Weihua; Wu Yunhua; Chen Shaoyong; Yin Kedong

    2003-01-01

    Concentrations of organic matter, iron and manganese in the deep sea surface sediments in the Nansha Islands sea area, South China Sea are measured. Horizontal and vertical distributions of iron and manganese are discussed. The vertical distribution of iron and manganese in the sediments results from reduction, diffusion, and redeposition of manganese (or iron) oxide and hydroxide in the sediment. There are the maxima of iron and manganese in solid phase in the top of the sediment, which is caused by the penetration of O2 and the upward flux of Mn2+ ( or Fe2+ ). Manganese bacteria play a very important role in the cycle of solid-phase iron and manganese in the ocean environment. Manganese bacteria oxidize Mn2+ ( or Fe2+ ) in dissolved state to Mn4+ ( or Fe3+ ) in oxidized state under the aerobic condition, whereas they reduce iron and manganese in anaerobic conditions.

  19. Surface reactivity, cytotoxicity, and transforming potency of iron-covered compared to untreated refractory ceramic fibers.

    Science.gov (United States)

    Elias, Zoé; Poirot, Odile; Danière, Marie-Céleste; Terzetti, Francine; Binet, Stéphane; Tomatis, Maura; Fubini, Bice

    2002-12-13

    Untreated and iron-coated refractory ceramic fibers (RCFs) 1, 3, and 4 were examined for their potential to generate free radicals and to catalyze hydrogen peroxide decomposition in cell-free assays and were compared for cytotoxic and transforming potencies in Syrian hamster embryo (SHE) cell system. Coating with a high quantity of iron increased the capability of RCFs to generate hydroxyl radicals and to catalyze the decomposition of hydrogen peroxide. In the SHE cells, the untreated RCFs had varying ability to induce inhibition of cell proliferation, cytotoxicity (as measured by the colony-forming efficiency, CE) and morphological transformation, in a concentration-dependent manner. According to cytotoxic and transforming potencies, they ranged as follows: RCF3 > RCF1 > RCF4. The lethal concentration 50 (LC50; decrease of CE to 50% of controls after 7 d of treatment) expressed per number of RCF3 and RCF1/cm(2) of culture dish was 2.5 x 10(4) and 3.7 x 10(4), respectively, whereas RCF4 was not cytotoxic up to the highest concentration tested (23.7 x 10(4) fibers/cm(2)). At LC50, RCF3 was 1.4-fold more transforming than RCF1, and the weakest, RCF4, induced less than 1% transformation. Iron coating of RCF1 and RCF3 markedly attenuated their cytostatic, cytotoxic, and transforming potencies without a linear concentration-transformation relationship. In contrast, iron coating of RCF4 affected slightly its low transforming potency, although the growth inhibitory effect was reduced. The observed decrease rather than increase in the cytotoxic and transforming potencies of the active samples RCF1 and RCF3 by their coating with large amounts of ferric iron suggests that it is not the quantity or any form of iron on the surface of fibers but the iron, even in trace, in a particular redox and coordinate state that might play a role in the fiber's surface reactivity with regard to the biological material. Surface chemical functions involved in the interaction with the cell

  20. Determination of picomolar levels of iron in seawater using catalytic cathodic stripping voltammetry.

    Science.gov (United States)

    Obata, H; van den Berg, C M

    2001-06-01

    A new procedure for the direct determination of picomolar levels of iron in seawater is presented. Cathodic stripping voltammetry (CSV) is preceded by adsorptive accumulation of the iron(III)-2,3-dihydroxynaphthalene (DHN) complex from seawater, containing 20 microM DHN at pH 8.0, onto a static mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is catalytically enhanced by the presence of 20 mM bromate. Optimized conditions include a 60-s adsorption period at -0.1 V and a voltammetric scan using sampled dc modulation at 10 Hz. In these conditions, a detection limit of 13 pM iron in seawater was achieved which can be lowered further by extending the adsorption time to 300 s. The new catalytic CSV method is approximately 5 times more sensitive than existing CSV methods and was tested on samples from the Atlantic Ocean.

  1. Surface reactions of iron - enriched smectites: adsorption and transformation of hydroxy fatty acids and phenolic acids

    Science.gov (United States)

    Polubesova, Tamara; Olshansky, Yaniv; Eldad, Shay; Chefetz, Benny

    2014-05-01

    Iron-enriched smectites play an important role in adsorption and transformation of soil organic components. Soil organo-clay complexes, and in particular humin contain hydroxy fatty acids, which are derived from plant biopolymer cutin. Phenolic acids belong to another major group of organic acids detected in soil. They participate in various soil processes, and are of concern due to their allelopathic activity. We studied the reactivity of iron-enriched smectites (Fe(III)-montmorillonite and nontronite) toward both groups of acids. We used fatty acids- 9(10),16-dihydroxypalmitic acid (diHPA), isolated from curtin, and 9,10,16-trihydroxypalmitic acid (triHPA); the following phenolic acids were used: ferulic, p-coumaric, syringic, and vanillic. Adsorption of both groups of acids was measured. The FTIR spectra of fatty acid-mineral complexes indicated inner-sphere complexation of fatty acids with iron-enriched smectites (versus outer-sphere complexation with Ca(II)-montmorillonite). The LC-MS results demonstrated enhanced esterification of fatty acids on the iron-enriched smectite surfaces (as compared to Ca(II)-montmorillonite). This study suggests that fatty acids can be esterified on the iron-enriched smectite surfaces, which results in the formation of stable organo-mineral complexes. These complexes may serve as a model for the study of natural soil organo-clay complexes and humin. The reaction of phenolic acids with Fe(III)-montmorillonite demonstrated their oxidative transformation by the mineral surfaces, which was affected by molecular structure of acids. The following order of their transformation was obtained: ferulic >syringic >p-coumaric >vanillic. The LC-MS analysis demonstrated the presence of dimers, trimers, and tetramers of ferulic acid on the surface of Fe(III)-montmorillonite. Oxidation and transformation of ferulic acid were more intense on the surface of Fe(III)-montmorillonite as compared to Fe(III) in solution due to stronger complexation on

  2. Combinatorial effects of malaria season, iron deficiency, and inflammation determine plasma hepcidin concentration in African children.

    Science.gov (United States)

    Atkinson, Sarah H; Armitage, Andrew E; Khandwala, Shivani; Mwangi, Tabitha W; Uyoga, Sophie; Bejon, Philip A; Williams, Thomas N; Prentice, Andrew M; Drakesmith, Hal

    2014-05-22

    Hepcidin is the master regulatory hormone that governs iron homeostasis and has a role in innate immunity. Although hepcidin has been studied extensively in model systems, there is less information on hepcidin regulation in global health contexts where iron deficiency (ID), anemia, and high infectious burdens (including malaria) all coexist but fluctuate over time. We evaluated iron status, hepcidin levels, and determinants of hepcidin in 2 populations of rural children aged ≤8 years, in the Gambia and Kenya (total n = 848), at the start and end of a malaria season. Regression analyses and structural equation modeling demonstrated, for both populations, similar combinatorial effects of upregulating stimuli (iron stores and to a lesser extent inflammation) and downregulating stimuli (erythropoietic drive) on hepcidin levels. However, malaria season was also a significant factor and was associated with an altered balance of these opposing factors. Consistent with these changes, hepcidin levels were reduced whereas the prevalence of ID was increased at the end of the malaria season. More prevalent ID and lower hepcidin likely reflect an enhanced requirement for iron and an ability to efficiently absorb it at the end of the malaria season. These results, therefore, have implications for ID and malaria control programs. © 2014 by The American Society of Hematology.

  3. [Determination of Total Iron and Fe2+ in Basalt].

    Science.gov (United States)

    Liu, Jian-xun; Chen, Mei-rong; Jian, Zheng-guo; Wu, Gang; Wu, Zhi-shen

    2015-08-01

    Basalt is the raw material of basalt fiber. The content of FeO and Fe2O3 has a great impact on the properties of basalt fibers. ICP-OES and dichromate method were used to test total Fe and Fe(2+) in basalt. Suitable instrument parameters and analysis lines of Fe were chosen for ICP-OES. The relative standard deviation (RSD) of ICP-OES is 2.2%, and the recovery is in the range of 98%~101%. The method shows simple, rapid and highly accurate for determination of total Fe and Fe(2+) in basalt. The RSD of ICP-OES and dichromate method is 0.42% and 1.4%, respectively.

  4. A Course at the Master Level Demonstrating Quality Assurance by Spectrophotometric Determination of Iron in two experiments

    DEFF Research Database (Denmark)

    In two experiments, the first a batch determination of iron, and the second determination of iron by flow injection analysis, the students perform a number of repetitions. The measurements were repeated until it became possible to estimate which one of the two methods exhibited the better perform...

  5. Spectrophotometric determination of iron species using ionic liquid ultrasound assisted dispersive liquid--liquid microextraction

    OpenAIRE

    BAZMANDEGAN, ALIREZA; Shabani,Ali Mohammad Haji; DADFARNIA, SAYESSTEH; Saeidi, Mahboubeh; Moghadam,Masoud Rohani

    2015-01-01

    A simple and efficient method for speciation and determination of iron in different water samples was developed. The method is based on ionic liquid ultrasound assisted dispersive liquid--liquid microextraction (IL-USA-DLLME) followed by spectrophotometric determination. Fe(II) is complexed with 2,4,6-tri(2'-pyridyl)-l,3,5-triazine (TPTZ{)}, neutralized through ion pair formation with sodium dodecyl sulfate (SDS) and extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate [C$_...

  6. INCREASING AND DECREASING PHASES OF FERRITIN AND HEMOSIDERIN IRON DETERMINED BY SERUM FERRITIN KINETICS

    Science.gov (United States)

    SAITO, HIROSHI; HAYASHI, HISAO; TOMITA, AKIHIRO; OHASHI, HARUHIKO; MAEDA, HIDEAKI; NAOE, TOMOKI

    2013-01-01

    ABSTRACT We attempted to clarify the mechanism of the storage iron metabolism. A new program of serum ferritin kinetics was applied for studying the increasing and decreasing phases of ferritin and hemosiderin iron in iron addition and removal in patients with a normal level of iron stores or iron overload. The change of ferritin iron in response to iron addition and removal was rapid in the initial stage, but it was slow later. In contrast, the change of hemosiderin iron was slow in the initial stage, but it became rapid later. These changes of ferritin and hemosiderin iron suggest that the turnover of ferritin iron is preferential to that of hemosiderin iron, and that the initially existed ferritin iron is gradually replaced by the ferritin iron recovered by taking iron from hemosiderin in iron mobilization. The crossing of the increasing curves of ferritin and hemosiderin iron in iron addition indicates a switching of the principal storage iron from ferritin to hemosiderin. The crossing point shifted toward a higher storage iron level in the increase of iron deposition. Iron storing capacity can be increased not only by the transformation of ferritin into hemosiderin, but also by the expansion of cell space as seen by hepatomegaly in hereditary hemochromatosis. The amounts of hemosiderin iron exceeded ferritin iron in all 10 patients with chronic hepatitis C even though they had normal storage iron levels. This suggests it is difficult to store iron in the form of ferritin in chronic hepatitis C. PMID:24640177

  7. Accessible reactive surface area and abiotic redox reactivity of iron oxyhydroxides in acidic brines

    Science.gov (United States)

    Strehlau, Jennifer H.; Toner, Brandy M.; Arnold, William A.; Penn, R. Lee

    2017-01-01

    The reactivity of iron oxyhydroxide nanoparticles in low pH and high ionic strength solutions was quantified to assess abiotic contributions to oxidation-reduction chemistry in acidic brine environments, such as mine groundwater seepage, lakes in Western Australia, and acid mine drainage settings, which are of global interest for their environmental impacts and unique geomicrobiology. Factors expected to influence accessible and reactive surface area, including Fe(II) adsorption and aggregate size, were measured as a function of pH and CaCl2 concentration and related to the kinetics of redox reactions in aqueous suspensions of synthetic goethite (α-FeOOH), akaganeite (β-FeOOH), and ferrihydrite (Fe10O14(OH)2) nanoparticles. Aqueous conditions and iron oxyhydroxides were chosen based on characterization of natural iron-rich mine microbial mats located in Soudan Underground Mine State Park, Minnesota, USA. Quinone species were used as redox sensors because they are well-defined probes and are present in natural organic matter. Fe(II) adsorption to the iron oxyhydroxide mineral surfaces from aqueous solution was measurable only at pH values above 4 and either decreased or was not affected by CaCl2 concentration. Concentrations at or above 0.020 M CaCl2 in acetate buffer (pH 4.5) induced particle aggregation. Assessment of Fe(II) adsorption and particle aggregation in acidic brine suggested that accessible reactive surface area may be limited in acidic brines. This was supported by observations of decreasing benzoquinone reduction rate by adsorbed Fe(II) at high CaCl2 concentration. In contrast, the hydroquinone oxidation rate increased at high CaCl2 concentrations, which may be due to suppressed adsorption of Fe(II) generated by the reaction. Results suggest that iron geochemical cycling in acidic brine environments will be substantially different than for iron oxyhydroxides in low-saline waters with circumneutral pH. These findings have implications for acidic

  8. Effect of surface charge on the colloidal stability and in vitro uptake of carboxymethyl dextran-coated iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, Vanessa; Herrera, Adriana P.; Latorre-Esteves, Magda; Torres-Lugo, Madeline [University of Puerto Rico, Department of Chemical Engineering (United States); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [University of Florida, J. Crayton Pruitt Family Department of Biomedical Engineering (United States)

    2013-08-15

    Nanoparticle physicochemical properties such as surface charge are considered to play an important role in cellular uptake and particle-cell interactions. In order to systematically evaluate the role of surface charge on the uptake of iron oxide nanoparticles, we prepared carboxymethyl-substituted dextrans with different degrees of substitution, ranging from 38 to 5 groups per chain, and reacted them using carbodiimide chemistry with amine-silane-coated iron oxide nanoparticles with narrow size distributions in the range of 33-45 nm. Surface charge of carboxymethyl-substituted dextran-coated nanoparticles ranged from -50 to 5 mV as determined by zeta potential measurements, and was dependent on the number of carboxymethyl groups incorporated in the dextran chains. Nanoparticles were incubated with CaCo-2 human colon cancer cells. Nanoparticle-cell interactions were observed by confocal laser scanning microscopy and uptake was quantified by elemental analysis using inductively coupled plasma mass spectroscopy. Mechanisms of internalization were inferred using pharmacological inhibitors for fluid-phase, clathrin-mediated, and caveola-mediated endocytosis. Results showed increased uptake for nanoparticles with greater negative charge. Internalization patterns suggest that uptake of the most negatively charged particles occurs via non-specific interactions.

  9. Dietary Determinants of and Possible Solutions to Iron Deficiency for Young Women Living in Industrialized Countries: A Review

    Directory of Open Access Journals (Sweden)

    Kathryn L. Beck

    2014-09-01

    Full Text Available Iron deficiency is a concern in both developing and developed (industrialized countries; and young women are particularly vulnerable. This review investigates dietary determinants of and possible solutions to iron deficiency in young women living in industrialized countries. Dietary factors including ascorbic acid and an elusive factor in animal protein foods (meat; fish and poultry enhance iron absorption; while phytic acid; soy protein; calcium and polyphenols inhibit iron absorption. However; the effects of these dietary factors on iron absorption do not necessarily translate into an association with iron status and iron stores (serum ferritin concentration. In cross-sectional studies; only meat intake has consistently (positively been associated with higher serum ferritin concentrations. The enhancing effects of ascorbic acid and meat on iron absorption may be negated by the simultaneous consumption of foods and nutrients which are inhibitory. Recent cross-sectional studies have considered the combination and timing of foods consumed; with mixed results. Dietary interventions using a range of focused dietary measures to improve iron status appear to be more effective than dietary approaches that focus on single nutrients or foods. Further research is needed to determine optimal dietary recommendations for both the prevention and treatment of iron deficiency.

  10. Electrolytic surface hardening of steel,cast iron and aluminium-bronze

    Institute of Scientific and Technical Information of China (English)

    Suhas Keshav Paknikar

    2006-01-01

    Electrolytic hardening process was developed in USSR in the 1950s. The process was developed but was not commercially exploited. There is no evidence of work done on this process in India. The author has done this original work applied to different materials like steel,cast iron and aluminum-bronze. This paper gives details of microstructural transformations along with hardness value achieved. There is vital scope for this process to become viable for surface hardening and selective hardening of small components.

  11. Determination of Rate of Degradation of Iron Plates Due To Rust Using Image Processing -A Review

    Directory of Open Access Journals (Sweden)

    Priyanka Choudhary

    2014-03-01

    Full Text Available Abstract: most of industries and bridges around us make use of iron for manufacturing their products. On the other hand corrosion is a natural process that deteriorates the integrity of iron surface. Therefore, rusting of iron takes place. To avoid unwanted accidents in industries and bridges, it is necessary to detect rusting in earlier stage, so that it can be prevented. Digital image processing for the detection of the rusting provides fast, accurate and objectives results. In this research paper, we have done a systematic review of algorithms that help us to detect the rust area from a metal (iron.it has been found that most of researches are bring their images, processing series in usage for this purpose due to its simplicity in implementing and due to fact the images help capturing the visual inspection process easily and due to the ground teeth. The image processing techniques explored by other peoples based on in-depth analysis, we have also proposed a novel technique to overcome the limitation.

  12. Determination of Rate of Degradation of Iron Plates due to Rust using Image Processing

    Directory of Open Access Journals (Sweden)

    Priyanka Choudhary

    2015-02-01

    Full Text Available Most of industries and bridges around us make use of iron for manufacturing their products. On the other hand corrosion is a natural process that deteriorates the integrity of iron surface. Therefore, rusting of iron takes place. To avoid unwanted accidents in industries and bridges, it is necessary to detect rusting in earlier stage, so that it can be prevented. Digital image processing for the detection of the rusting provides fast, accurate and objectives results. In this research paper, we have done a systematic review of algorithms that help us to detect the rust area from a metal (iron.it has been found that most of researches are bring their images, processing series in usage for this purpose due to its simplicity in implementing and due to fact the images help capturing the visual inspection process easily and due to the ground teeth. The image processing techniques explored by other peoples based on in-depth analysis, we have also proposed a novel technique to overcome the limitation.

  13. Charge effect of superparamagnetic iron oxide nanoparticles on their surface functionalization by photo-initiated chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Javanbakht, Taraneh [Ecole Polytechnique of Montreal, Department of Chemical Engineering (Canada); Laurent, Sophie; Stanicki, Dimitri [University of Mons, Laboratory of NMR and Molecular Imaging (Belgium); Raphael, Wendell; Tavares, Jason Robert, E-mail: jason.tavares@polymtl.ca [Ecole Polytechnique of Montreal, Department of Chemical Engineering (Canada)

    2015-12-15

    Diverse applications of superparamagnetic iron oxide nanoparticles (SPIONs) in the chemical and biomedical industry depend on their surface properties. In this paper, we investigate the effect of initial surface charge (bare, positively and negatively charged SPIONs) on the resulting physicochemical properties of the particles following treatment through photo-initiated chemical vapour deposition (PICVD). Transmission electron microscopy shows a nanometric polymer coating on the SPIONs and contact angle measurements with water demonstrate that their surface became non-polar following functionalization using PICVD. FTIR and XPS data confirm the change in the chemical composition of the treated SPIONs. Indeed, XPS data reveal an initial charge-dependent increase in the surface oxygen content in the case of treated SPIONs. The O/C percentage ratios of the bare SPIONs increase from 1.7 to 1.9 after PICVD treatment, and decrease from 1.7 to 0.7 in the case of negatively charged SPIONs. The ratio remains unchanged for positively charged SPIONs (1.7). This indicates that bare and negatively charged SPIONs showed opposite preference for the oxygen or carbon attachment to their surface during their surface treatment. These results reveal that both the surface charge and stereochemical effects have determinant roles in the polymeric coating of SPIONs with PICVD. Our findings suggest that this technique is appropriate for the treatment of nanoparticles.Graphical Abstract.

  14. Analysis of novel iron-regulated, surface-anchored hemin-binding proteins in Corynebacterium diphtheriae.

    Science.gov (United States)

    Allen, Courtni E; Burgos, Jonathan M; Schmitt, Michael P

    2013-06-01

    Corynebacterium diphtheriae utilizes hemin and hemoglobin (Hb) as iron sources during growth in iron-depleted environments, and recent studies have shown that the surface-exposed HtaA protein binds both hemin and Hb and also contributes to the utilization of hemin iron. Conserved (CR) domains within HtaA and in the associated hemin-binding protein, HtaB, are required for the ability to bind hemin and Hb. In this study, we identified and characterized two novel genetic loci in C. diphtheriae that encode factors that bind hemin and Hb. Both genetic systems contain two-gene operons that are transcriptionally regulated by DtxR and iron. The gene products of these operons are ChtA-ChtB and ChtC-CirA (previously DIP0522-DIP0523). The chtA and chtB genes are carried on a putative composite transposon associated with C. diphtheriae isolates that dominated the diphtheria outbreak in the former Soviet Union in the 1990s. ChtA and ChtC each contain a single N-terminal CR domain and exhibit significant sequence similarity to each other but only limited similarity with HtaA. The chtB and htaB gene products exhibited a high level of sequence similarity throughout their sequences, and both proteins contain a single CR domain. Whole-cell binding studies as well as protease analysis indicated that all four of the proteins encoded by these two operons are surface exposed, which is consistent with the presence of a transmembrane segment in their C-terminal regions. ChtA, ChtB, and ChtC are able to bind hemin and Hb, with ChtA showing the highest affinity. Site-directed mutagenesis showed that specific tyrosine residues within the ChtA CR domain were critical for hemin and Hb binding. Hemin iron utilization assays using various C. diphtheriae mutants indicate that deletion of the chtA-chtB region and the chtC gene has no affect on the ability of C. diphtheriae to use hemin or Hb as iron sources; however, a chtB htaB double mutant exhibits a significant decrease in hemin iron use

  15. Iron availability in an enteral feeding formulation by response surface methodology for mixtures

    Directory of Open Access Journals (Sweden)

    Luciana Bueno

    2013-02-01

    Full Text Available Background: The nutritional therapy with enteral diets has been getting specialized and those formulations to substitute the traditional diet for those patients who need to be fed by probe. This workís aim was to study the effect of the components of enteral diet formulation: fiber, calcium and medium-chain triglycerides, seeking optimize a formulation for the best dialysability of iron by Response Surface Methodology (RSM. Methods: The ingredients used for the formulations of the diet were chosen according to the ones commercialized in the modules of a standard enteral diet, with which it was made an experimental diet and the applicability of the experimental limits. Results: The found results in the model have shown that it depends on the proportion of the nutrients that were manipulated in the experimental design. When the level curve was obtained for the iron dialysable, it could be verified that the binary interaction fiber-calcium was the one that presented more synergism for the appraised formulation. Before the analyzed facts, the best formulation of enteral diet optimized for the dialysability of the iron was the proportion of 60% of fiber and 40% of calcium, showing to be the best formulation of the enteral diet for the availability of the iron.

  16. A method for determination of [Fe3+]/[Fe2+] ratio in superparamagnetic iron oxide

    Science.gov (United States)

    Jiang, Changzhao; Yang, Siyu; Gan, Neng; Pan, Hongchun; Liu, Hong

    2017-10-01

    Superparamagnetic iron oxide nanoparticles (SPION), as a kind of nanophase materials, are widely used in biomedical application, such as magnetic resonance imaging (MRI), drug delivery, and magnetic field assisted therapy. The magnetic property of SPION has close connection with its crystal structure, namely it is related to the ratio of Fe3+ and Fe2+ which form the SPION. So a simple way to determine the content of the Fe3+ and Fe2+ is important for researching the property of SPION. This review covers a method for determination of the Fe3+ and Fe2+ ratio in SPION by UV-vis spectrophotometry based the reaction of Fe2+ and 1,10-phenanthroline. The standard curve of Fe with R2 = 0.9999 is used for determination the content of Fe2+ and total iron with 2.5 mL 0.01% (w/v) SPION digested by HCl, pH = 4.30 HOAc-NaAc buffer 10 mL, 0.01% (w/v) 1,10-phenanthroline 5 mL and 10% (w/v) ascorbic acid 1 mL for total iron determine independently. But the presence of Fe3+ interfere with obtaining the actual value of Fe2+ (the error close to 9%). We designed a calibration curve to eliminate the error by devising a series of solution of different ratio of [Fe3+]/[Fe2+], and obtain the calibration curve. Through the calibration curve, the error between the measured value and the actual value can be reduced to 0.4%. The R2 of linearity of the method is 0.99441 and 0.99929 for Fe2+ and total iron respectively. The error of accuracy of recovery and precision of inter-day and intra-day are both lower than 2%, which can prove the reliability of the determination method.

  17. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    Science.gov (United States)

    Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

    2016-10-01

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION.

  18. Determining Fault Geometries From Surface Displacements

    Science.gov (United States)

    Volkov, D.; Voisin, C.; Ionescu, I. R.

    2017-02-01

    We introduce a new algorithm for determining the geometry of active parts of faults. This algorithm uses surface measurements of displacement fields and local modeling of the Earth's crust as a half-space elastic medium. The numerical method relies on iterations alternating non-linear steps for recovering the geometry and linear steps for reconstructing slip fields. Our algorithm greatly improves upon past attempts at reconstructing fault profiles. We argue that these past attempts suffered from either the restrictive assumption that the geometry of faults can be derived using only uniformly constant slips or that they relied on arbitrary assumptions on the statistics of the reconstruction error. We test this algorithm on the 2006 Guerrero, Mexico, slow slip event (SSE) and on the 2009 SSE for the same region. These events occurred on a relatively well-known subduction zone, whose geometry was derived from seismicity and gravimetric techniques, see Kostoglodov et al. (Geophys Res Lett 23(23):3385-3388, 1996), Pardo and Suarez (J Geophys Res 100(B7):357-373, 1995), Singh and Pardo (Geophys Res Lett 20(14):1483-1486, 1993), so our results can be compared to known benchmarks. Our derived geometry is found to be consistent with these benchmarks regarding dip and strike angles and the positioning of the North American Trench. In addition, our derived slip distribution is also consistent with previous studies (all done with an assumed fixed geometry), see Larson et al. (Geophys Res Lett 34(13), 2007), Bekaert et al. (J Geophys Res: Solid Earth 120(2):1357-1375, 2015), Radiguet et al. (Geophys J Int 184(2):816-828, 2011, J Geophys Res 2012), Rivet et al. (Geophys Res Lett 38(8), 2011), Vergnolle et al. (J Geophys Res: Solid Earth 115(B8), 2010), Walpersdorf et al. Geophys Res Lett 38(15), 2011), to name a few. We believe that the new computational inverse method introduced in this paper holds great promise for applications to blind inversion cases, where both geometry and

  19. Determination of the fatigue limit of an austempered ductile iron using thermal infrared imagry

    Science.gov (United States)

    Geraci, Alberto L.; La Rosa, Guido; Risitano, Antonino; Grech, Maurice

    1995-12-01

    Previous work by the authors showed that the endurance limit of specimens, or mechanical components, can be predicted using thermal infrared imagery. The new technique enables the determination of the fatigue strength limit in a comparatively short period of time (few thousands cycles), and using very few specimens (theoretically only 1). The present work applies this technique to rotating-bending test specimens of austempered ductile iron, an alloy whose fatigue limit is, due to the high scatter dispersion of the data points and the long testing period required, generally difficult to determine by the traditional technique. This material exhibited higher fatigue strength than the familiar nodular cast iron. This was confirmed by the results derived from the traditional Wohler test and the new technique, and supported by the data gathered from literature.

  20. Determination of oxidation state of iron in normal and pathologically altered human aortic valves

    Energy Technology Data Exchange (ETDEWEB)

    Czapla-Masztafiak, J. [Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Kraków (Poland); Lis, G.J.; Gajda, M.; Jasek, E. [Department of Histology, Jagiellonian University Medical College, Kopernika 7, 31-034 Kraków (Poland); Czubek, U. [Department of Coronary Disease, Jagiellonian University Medical College, John Paul II Hospital, Prądnicka 80, 31-202 Kraków (Poland); Bolechała, F. [Department of Forensic Medicine, Jagiellonian University Medical College, Grzegórzecka 16, 31-531 Kraków (Poland); Borca, C. [Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Kwiatek, W.M. [Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Kraków (Poland)

    2015-12-01

    In order to investigate changes in chemical state of iron in normal and pathologically altered human aortic valves X-ray absorption spectroscopy was applied. Since Fe is suspected to play detrimental role in aortic valve stenosis pathogenesis the oxidation state of this element has been determined. The experimental material consisted of 10 μm sections of valves excised during routine surgery and from autopsies. The experiment was performed at the MicroXAS beamline of the SLS synchrotron facility in Villigen (Switzerland). The Fe K-edge XANES spectra obtained from tissue samples were carefully analyzed and compared with the spectra of reference compounds containing iron in various chemical structures. The analysis of absorption edge position and shape of the spectra revealed that both chemical forms of iron are presented in valve tissue but Fe{sup 3+} is the predominant form. Small shift of the absorption edge toward higher energy in the spectra from stenotic valve samples indicates higher content of the Fe{sup 3+} form in pathological tissue. Such a phenomenon suggests the role of Fenton reaction and reactive oxygen species in the etiology of aortic valve stenosis. The comparison of pre-edge regions of XANES spectra for control and stenotic valve tissue confirmed no differences in local symmetry or spin state of iron in analyzed samples.

  1. Determination of anisotropy constants of protein encapsulated iron oxide nanoparticles by electron magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongyan [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Klem, Michael T.; Sebby, Karl B.; Singel, David J. [Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Young, Mark [Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Douglas, Trevor [Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Idzerda, Yves U. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States)], E-mail: Idzerda@montana.edu

    2009-02-15

    Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19 nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1 T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles' easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size.

  2. Determination of ferrous iron in rock and mineral samples by three volumetric methods

    OpenAIRE

    Saikkonen, R.J.; Rautiainen, I.A.

    1993-01-01

    Ferrous iron was determined by three volumetric methods in 13 in-house reference rock samples and in 31 international geological reference samples. The methods used were Amonette & Scott' s oxidimetric method, Wilson's oxidimetric method and Pratt's method. The results for FeO by these volumetric methods in 13 in-house rock samples were compared to the results obtained in other analytical laboratories in Finland. The results for FeO in the international samples were compared with published da...

  3. Mars surface weathering products and spectral analogs: Palagonites and synthetic iron minerals

    Science.gov (United States)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Lauer, H. V., Jr.

    1992-01-01

    There are several hypotheses regarding the formation of Martian surface fines. These surface fines are thought to be products of weathering processes occurring on Mars. Four major weathering environments of igneous rocks on Mars have been proposed; (1) impact induced hydrothermal alterations; (2) subpermafrost igneous intrusion; (3) solid-gas surface reactions; and (4) subaerial igneous intrusion over permafrost. Although one or more of these processes may be important on the Martian surface, one factor in common for all these processes is the reaction of solid or molten basalt with water (solid, liquid, or gas). These proposed processes, with the exception of solid-gas surface reactions, are transient processes. The most likely product of transient hydrothermal processes are layer silicates, zeolites, hydrous iron oxides and palagonites. The long-term instability of hydrous clay minerals under present Martian conditions has been predicted; however, the persistence of such minerals due to slow kinetics of dehydration, or entrapment in permafrost, where the activity of water is high, can not be excluded. Anhydrous oxides of iron (e.g., hematite and maghemite) are thought to be stable under present Martian surface conditions. Oxidative weathering of sulfide minerals associated with Martian basalts has been proposed. Weathering of sulfide minerals leads to a potentially acidic permafrost and the formation of Fe(3) oxides and sulfates. Weathering of basalts under acidic conditions may lead to the formation of kaolinite through metastable halloysite and metahalloysite. Kaolinite, if present, is thought to be a thermodynamically stable phase at the Martian surface. Fine materials on Mars are important in that they influence the surface spectral properties; these fines are globally distributed on Mars by the dust storms and this fraction will have the highest surface area which should act as a sink for most of the absorbed volatiles near the surface of Mars. Therefore

  4. Correlation between serum ferritin levels and liver iron concentration determined by MR imaging : impact of hematologic disease and inflammation

    NARCIS (Netherlands)

    Olthof, Allard W.; Sijens, Paul E.; Kreeftenberg, Herman G.; Kappert, Peter; Irwan, Roy; van der Jagt, Eric J.; Oudkerk, Matthijs

    Liver iron concentration was determined in 28 patients by magnetic resonance imaging using the method of Gandon et al. (Non-invasive assessment of hepatic iron stores by MRI. Lancet 2004;363:357-362). The result showed a significant correlation with blood plasma ferritin content (Spearman's r = .66;

  5. Membrane preconcentration of iron in seawater samples and on-site determination in spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    PENG Yuanzhen; YUAN Dongxing; HUANG Yongming; JIANG Tao; LIU Baomin

    2012-01-01

    A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection.Fe(Ⅱ)-ferrozine complex was reacted with cetyltrimethylammonium bromide (CTAB) to form a Fe(Ⅱ)-ferrozine-CTAB paired compound,which was collected on a membrane by filtration under vacuum.The membrane was immersed in 2 mL of ethanol-nitric acid and the absorbance of the solution measured for quantitative analysis.Various factors affecting the iron collection and determination were investigated.With different sample preconcentration volumes,the range of determination was broadened to 0.5-120 μg/L.The detection limit of this method reached 0.19 μg/L and the recoveries were between 97.2 and 109% when the concentration enrichment was about 45.The relative standard deviation (n =7) was 1.9% for samples containing 10 μg/L Fe.Twelve seawater samples were analyzed on-site using the proposed method,and two were also analyzed in inductively coupled plasma mass spectrometry.No significant difference was shown between the two methods by the Student's t-test.The method has also been used on-site for iron enrichment experiments with phytoplankton and concluded to be simple,accurate and inexpensive.

  6. Evaluation of cutting force and surface roughness in high-speed milling of compacted graphite iron

    Directory of Open Access Journals (Sweden)

    Azlan Suhaimi Mohd

    2017-01-01

    Full Text Available Compacted Graphite Iron, (CGI is known to have outstanding mechanical strength and weight-to-strength ratio as compared to conventional grey cast iron, (CI. The outstanding characteristics of CGI is due to its graphite particle shape, which is presented as compacted vermicular particle. The graphite is interconnected with random orientation and round edges, which results in higher mechanical strength. Whereas, graphite in the CI consists of a smooth-surfaced flakes that easily propagates cracks which results in weaker and brittle properties as compared to CGI. Owing to its improved properties, CGI is considered as the best candidate material in substituting grey cast iron that has been used in engine block applications for years. However, the smooth implementation of replacing CI with CGI has been hindered due to the poor machinability of CGI especially at high cutting speed. The tool life is decreased by 20 times when comparing CGI with CI under the same cutting condition. This study investigates the effect of using cryogenic cooling and minimum quantity lubrication (MQL during high-speed milling of CGI (grade 450. Results showed that, the combination of internal cryogenic cooling and enhanced MQL improved the tool life, cutting force and surface quality as compared to the conventional flood coolant strategy during high-speed milling of CGI.

  7. Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications

    Science.gov (United States)

    Wu, Wei; Wu, Zhaohui; Yu, Taekyung; Jiang, Changzhong; Kim, Woo-Sik

    2015-04-01

    This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed.

  8. Relating the Surface Properties of Superparamagnetic Iron Oxide Nanoparticles (SPIONs to Their Bactericidal Effect towards a Biofilm of Streptococcus mutans.

    Directory of Open Access Journals (Sweden)

    Taraneh Javanbakht

    Full Text Available This study was designed to determine the effects of superparamagnetic iron oxide nanoparticles (SPIONs on the biological activity of a bacterial biofilm (Streptococcus mutans. Our hypothesis was that the diffusion of the SPIONs into biofilms would depend on their surface properties, which in turn would largely be determined by their surface functionality. Bare, positively charged and negatively charged SPIONs, with hydrodynamic diameters of 14.6 ± 1.4 nm, 20.4 ± 1.3 nm and 21.2 ± 1.6 nm were evaluated. Time-of-flight secondary ion mass spectrometry (TOF-SIMS and electrophoretic mobility (EPM measurements were used to confirm that carboxylic functional groups predominated on the negatively charged SPIONS, whereas amine functional groups predominated on the positively charged particles. Transmission electron microscopy (TEM showed the morphology and sizes of SPIONs. Scanning electron microscopy (SEM and EPM measurements indicated that the surfaces of the SPIONs were covered with biomolecules following their incubation with the biofilm. Bare SPIONs killed bacteria less than the positively charged SPIONs at the highest exposure concentrations, but the toxicity of the bare and positively charged SPIONs was the same for lower SPION concentrations. The positively charged SPIONs were more effective in killing bacteria than the negatively charged ones. Nonetheless, electrophoretic mobilities of all three SPIONs (negative, bare and positively charged became more negative following incubation with the (negatively-charged biofilm. Therefore, while the surface charge of SPIONS was important in determining their biological activity, the initial surface charge was not constant in the presence of the biofilm, leading eventually to SPIONS with fairly similar surface charges in situ. The study nonetheless suggests that the surface characteristics of the SPIONS is an important parameter controlling the efficiency of antimicrobial agents. The analysis of the CFU

  9. Determining fault geometries from surface displacements

    Science.gov (United States)

    Volkov, D.; Voisin, C.; Ionescu, I. R.

    2016-12-01

    We study in this paper a half space linear elasticity model for surface displacements caused by slip along underground faults. We prove uniqueness of the fault location and (piecewise planar) geometry and of the slip field for a given surface displacement field.We then introduce a reconstruction algorithm for the realistic case where only a finite number of surface measurements are available.After showing how this algorithm performs on simulated data and assessing the effect of noise, we apply it to measured data. The data was recorded during slow slip events in Guerrero, Mexico. Since this is a well studied subduction zone, it is possible to compareour inferred fault geometry to other reconstructions (obtained using different techniques), found in the literature.

  10. Magnetization of individual yeast cells by in situ formation of iron oxide on cell surfaces

    Science.gov (United States)

    Choi, Jinsu; Lee, Hojae; Choi, Insung S.; Yang, Sung Ho

    2017-09-01

    Magnetic functionalization of living cells has intensively been investigated with the aim of various bioapplications such as selective separation, targeting, and localization of the cells by using an external magnetic field. However, the magnetism has not been introduced to individual living cells through the in situ chemical reactions because of harsh conditions required for synthesis of magnetic materials. In this work, magnetic iron oxide was formed on the surface of living cells by optimizing reactions conditions to be mild sufficiently enough to sustain cell viability. Specifically, the reactive LbL strategy led to formation of magnetically responsive yeast cells with iron oxide shells. This facile and direct post-magnetization method would be a useful tool for remote manipulation of living cells with magnetic interactions, which is an important technique for the integration of cell-based circuits and the isolation of cell in microfluidic devices.

  11. A study on the fabrication of superhydrophobic iron surfaces by chemical etching and galvanic replacement methods and their anti-icing properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kunquan, E-mail: likunquan1987@gmail.com; Zeng, Xingrong, E-mail: psxrzeng@gmail.com; Li, Hongqiang, E-mail: hqli1979@gmail.com; Lai, Xuejun, E-mail: msxjlai@scut.edu.cn

    2015-08-15

    Graphical abstract: - Highlights: • Superhydrophobic iron surfaces were prepared by etching and replacement method. • The fabrication process was simple, time-saving and inexpensive. • Galvanic replacement method was more favorable to create roughness on iron surface. • The superhydrophobic iron surface showed excellent anti-icing properties. - Abstract: Hierarchical structures on iron surfaces were constructed by means of chemical etching by hydrochloric acid (HCl) solution or the galvanic replacement by silver nitrate (AgNO{sub 3}) solution. The superhydrophobic iron surfaces were successfully prepared by subsequent hydrophobic modification with stearic acid. The superhydrophobic iron surfaces were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and water contact angle (WCA). The effects of reactive concentration and time on the microstructure and the wetting behavior were investigated. In addition, the anti-icing properties of the superhydrophobic iron surfaces were also studied. The FTIR study showed that the stearic acid was chemically bonded onto the iron surface. With the HCl concentration increase from 4 mol/L to 8 mol/L, the iron surface became rougher with a WCA ranging from 127° to 152°. The AgNO{sub 3} concentration had little effect on the wetting behavior, but a high AgNO{sub 3} concentration caused Ag particle aggregates to transform from flower-like formations into dendritic crystals, owing to the preferential growth direction of the Ag particles. Compared with the etching method, the galvanic replacement method on the iron surface more favorably created roughness required for achieving superhydrophobicity. The superhydrophobic iron surface showed excellent anti-icing properties in comparison with the untreated iron. The icing time of water droplets on the superhydrophobic surface was delayed to 500 s, which was longer than that of 295 s for

  12. Determination of the surface drag coefficient

    DEFF Research Database (Denmark)

    Mahrt, L.; Vickers, D.; Sun, J.L.

    2001-01-01

    This study examines the dependence of the surface drag coefficient on stability, wind speed, mesoscale modulation of the turbulent flux and method of calculation of the drag coefficient. Data sets over grassland, sparse grass, heather and two forest sites are analyzed. For significantly unstable ...

  13. Removal of an iron matrix with polyoxyethylene-type surfactant-coated amberlite XAD-4 for the determination of trace impurities in high-purity iron.

    Science.gov (United States)

    Matsumiya, Hiroaki; Furuzawa, Shigeru; Hiraide, Masataka

    2005-08-15

    Admicellar sorbents for the removal of an iron matrix were prepared for the determination of trace impurities in high-purity iron. A 1.0-g amount of Amberlite XAD-4 (macroreticular styrene-divinylbenzene copolymer) was coated with 0.14-1.3 mmol of polyoxyethylene-type surfactants, including polyoxyethylene-4-tert-octylphenoxy ethers (Triton X series) and polyoxyethylene-4-isononylphenoxy ethers (PONPEs). The surfactant-coated XAD-4 was packed into a polypropylene column (7 mm i.d. x 50 mm high). A 5.0-cm(3) volume of sample solution was passed through the column at a flow rate of 0.5 cm(3) min(-1). Milligram amounts of iron(III) were effectively sorbed on the column from 8 mol dm(-3) hydrochloric acid solutions. Among the surfactants tested, polyoxyethylene(20)-4-isononylphenoxy ether (PONPE-20) showed the best performance: the iron leaked from the PONPE-20 column was 4 microg when 25 mg of iron(III) was introduced onto the column. Trace elements, such as Ti(IV), Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II), Pb(II), and Bi(III), were not retained on the column and thus quantitatively recovered in the column effluent. The effective separation of trace elements from an iron matrix allowed their accurate determinations by inductively coupled plasma-mass spectrometry or graphite furnace atomic absorption spectrometry. The detection limits (3sigma blank) were in the nanogram per gram range. The proposed method was successfully applied to the determination of trace impurities in high-purity iron samples.

  14. Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

    Institute of Scientific and Technical Information of China (English)

    HAO Jian-jun; MA Yue-jin; SHEN Yu-zeng

    2004-01-01

    Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.

  15. Ion-Selective Electrode for the Determination of Iron(III in Vitamin Formulations

    Directory of Open Access Journals (Sweden)

    Teixeira Marcos Fernando de S.

    1998-01-01

    Full Text Available A coated graphite-epoxy ion-selective electrode for iron(III, based on the ion-pair formed between [Fe(citrate2]3- and the tricaprylylmethylammonium cation (Aliquat 336 in a poly(vinylchloride (PVC matrix has been constructed. A thin membrane film of this ion-pair, dibutylphthalate (DBPh in PVC was deposited directly onto a Perspex® tube, which contained a graphite-epoxy conductor substrate. The coating solution was prepared by dissolving 30% (w/w of PVC in 10 mL of tetrahydrofuran following addition of 65% (w/w DBPh and 5% (w/w of the ionic pair. The effect of pH, citrate concentration and some cations on the electrode response has been investigated. The E(mV vs. log [Fe(citrate2]3- electrode response was linear for iron(III concentration from 1.0 x 10-3 mol/L to 1.0 x 10-1 mol/L in 1.0 mol/L citrate medium, with a slope of 19.3 ± 0.5 mV/decade and a useful lifetime of at least six months (more than 800 determinations for each polymeric membrane used. The detection limit was 7.5 x 10-4 mol/L and the relative standard deviation was less than 3% for a solution containing 5.0 x 10-3 mol/L of iron(III (n = 10. The application of this electrode for iron(III determination in samples of vitamin formulations is described. The results obtained with this procedure are in close agreement with those obtained using AA spectrophotometry (r = 0.9999.

  16. 蔗糖铁注射液铁含量测定方法的研究%Research on Content Determination of Iron in Iron Sucrose Injection

    Institute of Scientific and Technical Information of China (English)

    李莉; 汪一帆; 花传政

    2011-01-01

    蔗糖铁注射液是一种静脉铁注射剂,用以治疗缺铁性贫血.本文对比了原子吸收光谱法、氧化还原滴定法和络合滴定法,并对选用的络合滴定条件进行了全面考察.在盐酸和过氧化氢溶液的作用下,用氢氧化钠溶液调节pH至2.2~2.5,加Tiron指示剂,用乙二胺四醋酸二钠滴定液滴定至溶液显纯黄色,并计算铁含量.试验结果表明其精密度好,准确度高,成本低,是一种适合蔗糖铁注射液铁含量测定的方法.%Iron Sucrose Injection is a kind of intravenous iron injection that is used for treatment of iron-deficiency anemia. Three methods for content determination of iron in the iron sucrose injection-atomic absorption spectrometry, oxidation-reduction titration and EDTA complexometric titration were compared. The influence factors on EDTA complexometric titration method -pH, volume of HC1, H2O2 and indicator were investigated. The result showed that the EDTA complexometric titration has good accuracy, high precision and low cost, and it is appropriate for the determination of iron content in iron sucrose injection.

  17. Corrosive inorganic contamination on wafer surfaces after nickel-iron electroplating formation mechanisms and prevention

    Energy Technology Data Exchange (ETDEWEB)

    Kritzer, P. [Freudenberg Nonwovens KG, Technical Nonwovens Div., Weinheim (Germany); Diel, W.; Barber, P.H. [IBM Speichersysteme Deutschland GmbH, Mainz (Germany); Romankiw, L.T. [IBM Watson Research Center, Yorktown Heights, NY (United States)

    2001-11-01

    Electroplating of Nickel-Iron alloys is widely used in the production of magnetic heads for storage systems. Usually, the plating process is performed in acidic, salt-containing solutions. After the plating step, a complete removal of the plating salts is necessary to receive a clean surface. In disadvantageous cases, a precipitation of sticky particles is observed that cannot be removed from the plated surface without damaging the surface. Some of these substances (esp. nickel sulfates) might lead to severe local corrosion and thus might act as ''time-bomb'' in the later product. Non-corrosive precipitations (i.e. nickel hydroxides) strongly hinder or even prevent the following production steps. In the present paper, the mechanisms of the origin of the different kinds of precipitation are described and the principle actions for their prevention are given. An outlook is given for other possible technical applications. (orig.)

  18. Determination of Energy Fluxes Over Agricultural Surfaces

    OpenAIRE

    Josefina Argete

    1994-01-01

    An energy budget was conducted over two kinds if surfaces: grass and corn canopy. The net radiative flux and the soil heat flux were directly measured while the latent and sensible heat flux were calculated from the vertical profiles if wet and dry-bulb temperature and wind speed. The crop storage flux was also estimated. Using the gradient or aerodynamic equations, the calculated fluxes when compared to the measured fluxes in the context of an energy budget gave an SEE = 63 Wm-2 over grass a...

  19. Pumice from volcanoes: Its possible role for the iron and silica budget of the surface ocean and diatom growth

    Science.gov (United States)

    Teschner, C.; Olgun, N.; Duggen, S.; Croot, P.; Dietze, H.

    2009-04-01

    Volcanic eruptions can inject pumice in major amounts into the oceans. Pumice can swim in seawater as pumice rafts or single pieces for years and contain relatively high concentrations of iron and silica, mainly found in seawater-reactive, metastable glass. Yet it is unknown to what extent pumice can release iron and silica, important for diatom growth, to surface ocean water. We examined the release of iron and silica of pumice from Central American volcanoes in contact with natural seawater by means of Cathodic Stripping Voltammetry and standard photometry. Based on our data we focus on evaluating how pumice from volcanoes in Central America may have contributed to the budget of the key nutrients iron and silica in the Central Pacific Ocean. Our study also provides new constraints on the importance of pumice for the marine biogeochemical iron- and silica-cycle.

  20. Determination of Nickel and Manganese Contaminants in Pharmaceutical Iron Supplements Using Energy Dispersive X-ray Fluorescence.

    Science.gov (United States)

    Cardoso, Pedro; Amaro, Pedro; Santos, José Paulo; de Assis, Joaquim T; Carvalho, Maria Luisa

    2017-03-01

    In this study, we investigate the capability of energy dispersive X-ray fluorescence (EDXF) spectrometry in a triaxial geometry apparatus as a fast and nondestructive determination method of both dominant and contaminant elements in pharmaceutical iron supplements. The following iron supplements brands with their respective active ingredients were analyzed: Neutrofer fólico (iron gylcinate), Anemifer (iron(II) sulfate monohydrate), Noripurum (iron(III)-hydroxide polymaltose complex), Sulferbel (iron(II) sulfate monohydrate), and Combiron Fólico (carbonyl iron). Although we observe a good agreement between the iron content obtained by the present method and that indicated in the supplement's prescribed dose, we observe contamination by manganese and nickel of up to 180 μg and 36 μg, respectively. These contents correspond to 7.2% and 14.4% of the permitted daily exposure of manganese and nickel, respectively, for an average adult individual as determined by the European Medicine Agency (EMEA). The method was successfully validated against the concentrations of several certified reference materials of biological light matrices with similar concentrations of contaminants. Moreover, we also validated our method by comparing the concentrations with those obtained with the inductively coupled plasma-atomic emission technique.

  1. Chromate removal by surface-modified nanoscale zero-valent iron: Effect of different surface coatings and water chemistry.

    Science.gov (United States)

    Dong, Haoran; He, Qi; Zeng, Guangming; Tang, Lin; Zhang, Chang; Xie, Yankai; Zeng, Yalan; Zhao, Feng; Wu, Yanan

    2016-06-01

    This study investigated the correlation between the colloidal stability and reactivity of surface-modified nano zero-valent iron (SM-nZVI) as affected by the surface coating (i.e., polyacrylic acid [PAA] and starch) under various geochemical conditions. Generally, the colloidal stability of nZVI was enhanced with increasing loading of surface coating, while there is an optimum loading for the most efficient Cr(VI) removal by SM-nZVI. At lower loadings than the optimum loading, the surface coating could enhance the particle stabilization, facilitating the Cr(VI) reduction by providing more available surface sites. However, the over-loaded surface coating on the surface of nZVI particles decreased the Cr(VI) reduction due to the occupation of the reactive sites and the inhibition of the mass transfer of Cr(VI) ions from water to the particle surface by providing the electrostatic or steric repulsion. The effects of Ca(2+) ions or humic acid (HA) on the colloidal stability and reactivity of PAA-modified nZVI (P-nZVI) and starch-modified nZVI (S-nZVI) were examined. Differing stability behavior and reactivity were observed for different SM-nZVI. It was found that the presence of Ca(2+) or HA altered surface chemistry of SM-nZVI, the particle-particle interaction and the particle-contaminant interaction, and hence influencing the stability behavior and reactivity of the particles. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Adsorption of poly(vinyl formamide-co-vinyl amine) (PVFA-co-PVAm) polymers on zinc, zinc oxide, iron, and iron oxide surfaces.

    Science.gov (United States)

    Seifert, Susan; Simon, Frank; Baumann, Giesela; Hietschold, Michael; Seifert, Andreas; Spange, Stefan

    2011-12-06

    The adsorption of poly(vinyl formamide) (PVFA) and the statistic copolymers poly(vinyl formamide-co-vinyl amine) (PVFA-co-PVAm) onto zinc and iron metal particles as well as their oxides was investigated. The adsorbates were characterized by means of XPS, DRIFT spectroscopy, wet chemical analysis, and solvatochromic probes. Dicyano-bis-(1,10-phenanthroline)-iron(II) (1), 3-(4-amino-3-methylphenyl)-7-phenyl-benzo-[1,2-b:4,5-b']difuran-2,6-dione (2), and 4-tert-butyl-2-(dicyano-methylene)-5-[4-(diethylamino)-benzylidene]-Δ(3)-thiazoline (3) as solvatochromic probes were coadsorbed onto zinc oxide to measure various effects of surface polarity. The experimental findings showed that the adsorption mechanism of PVFA and PVFA-co-PVAm strongly depends on the degree of hydrolysis of PVFA and pH values and also on the kind of metal or metal oxide surfaces that were employed as adsorbents. The adsorption mechanism of PVFA/PVFA-co-PVAm onto zinc oxide and iron oxide surfaces is mainly affected by electrostatic interactions. Particularly in the region of pH 5, the adsorption of PVFA/PVFA-co-PVAm onto zinc and iron metal particles is additionally influenced by redox processes, dissolution, and complexation reactions.

  3. Characterization of Aluminum-Based-Surface Matrix Composites with Iron and Iron Oxide Fabricated by Friction Stir Processing

    Directory of Open Access Journals (Sweden)

    Essam R. I. Mahmoud

    2016-06-01

    Full Text Available Surface composite layers were successfully fabricated on an A 1050-H24 aluminum plate by dispersed iron (Fe and magnetite (Fe3O4 particles through friction stir processing (FSP. Fe and Fe3O4 powders were packed into a groove of 3 mm in width and 1.5 mm in depth, cut on the aluminum plate, and covered with an aluminum sheet that was 2-mm thick. A friction stir processing (FSP tool of square probe shape, rotated at a rate of 1000–2000 rpm, was plunged into the plate through the cover sheet and the groove, and moved along the groove at a travelling speed of 1.66 mm/s. Double and triple passes were applied. As a result, it is found that the Fe particles were homogenously distributed in the whole nugget zone at a rotation speed of 1000 rpm after triple FSP passes. Limited interfacial reactions occurred between the Fe particles and the aluminum matrix. On the other hand, the lower rotation speed (1000 rpm was not enough to form a sound nugget when the dispersed particles were changed to the larger Fe3O4. The Fe3O4 particles were dispersed homogenously in a sound nugget zone when the rotation speed was increased to 1500 rpm. No reaction products could be detected between the Fe3O4 particles and the aluminum matrix. The saturation magnetization (Ms of the Fe-dispersed nugget zone was higher than that of the Fe3O4-dispersed nugget zone. Moreover, there were good agreement between the obtained saturation magnetization values relative to that of pure Fe and Fe3O4 materials and the volume content of the dispersed particles in the nugget zone.

  4. Controls on Arsenic Retention in Surface and Subsurface Environments: Resolving the Impact of Iron Reduction

    Science.gov (United States)

    Tufano, K.; Fendorf, S.

    2007-12-01

    A transition from oxidizing to reducing conditions has long been implicated in increasing aqueous As concentrations. Confounding processes controlling the release of As, reductive transformation of ferrihydrite, a common Fe(III) (hydr)oxide, has recently been shown to promote As retention rather than release. Elucidating the processes controlling As desorption and subsequent migration in surface and subsurface environments and how environmental factors (for example, availability of labile carbon and duration/extent of flooding) affect these processes will allow predictions to be made regarding long-term stability of As in soil and sediment. In turn, this can aid in evaluating the likelihood of having measurable As in groundwater. To better resolve these processes, here we examine As desorption from ferrihydrite-coated sands pre-sorbed with As(III) at circumneutral pH under Fe-reducing conditions with the dissimilatory iron reducing bacterium (DIRB) Shewanella putrefaciens strain CN- 32. We reveal that upon iron reduction, transformation of As-bearing ferrihydrite results in As(III) retention. However, over time there is a shift from reductive transformation to reductive dissolution of the As-bearing Fe phase(s) coupled with prolonged release of As to the aqueous phase. Our results suggest that arsenic retention may increase or decrease depending on the type of iron oxide, secondary iron transformations, and duration of reducing conditions. Immediately following a transition to anaerobic conditions there is potential for As retention on newly formed ferric/ferrous (hydr)oxide phases; however prolonged reduction will result in both the dissolution of ferric/ferrous (hydr)oxides and release of aqueous arsenic.

  5. Experimental Oxidation of Iron Sulphides from Intertidal Surface Sediments: Stable Isotope Effects (S, O, C)

    Science.gov (United States)

    Ebersbach, F.; Böttcher, M. E.; Al-Raei, A. M.; Segl, M.

    2009-04-01

    Top intertidal sediments show a pronounced zone of activities of sulphate-reducing bacteria. Iron sulfides may be formed, but a substantial part is reoxidized to sulfate. Microbial or chemical reoxidation can be further enhanced by a resuspension of surface sediments by tidal currents or storms. The rates of the different processes depend on the site-secific sedimentological properties (e.g., grain size, iron and sulphur contents etc.). In the present study 3 different areas of the German Wadden Sea were studied: a mud flat in the Jade Bay, and sandy sediments in the intertidals of Spiekeroog and Sylt islands. The latter site is part of an in-situ lugworm-exclusion experiment. The goal was the experimental and field investigation of the fate of iron sulfides and the formation of sulphate upon resuspension of intertidal surface sediments in oxygenated seawater. All sites were geochemically analyzed for dissolved and solid phase iron, manganese, sulphur and carbon phases/species, and sulphate reduction rates were measured using radiotracers. Dissolved chloride and grain sizes analysis where additionally carried out. TOC, S and metal phase contents were higher in mud compared to sandy sediments. Field results demonstrate gross but only minor net sulphide production and a downcore increases in FeS contents, due to intense sulphide oxidation at the surface. Pyrite, on the other hand, was abundant through the sediments due to continuous sediment reworking. The fate of iron-sulphides and accumulation of sulphate as a function of time was followed in batch experiments using dark suspensions of surface sediments in site-bottom waters at room temperature. During the experiments, each sample was shaken continuously under exposition to oxygen, and sub-samples were taken at the beginning and after discrete time intervalls. A very fast oxidation rate of AVS led to a complete exhaustion within a day, whereas Cr(II)-reducible sulfur was inititially built up and then decreased

  6. Standard test method for determining nodularity and nodule count in ductile iron using image analysis

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method is used to determine the percent nodularity and the nodule count per unit area (that is, number of nodules per mm2) using a light microscopical image of graphite in nodular cast iron. Images generated by other devices, such as a scanning electron microscope, are not specifically addressed, but can be utilized if the system is calibrated in both x and y directions. 1.2 Measurement of secondary or temper carbon in other types of cast iron, for example, malleable cast iron or in graphitic tool steels, is not specifically included in this standard because of the different graphite shapes and sizes inherent to such grades 1.3 This standard deals only with the recommended test method and nothing in it should be construed as defining or establishing limits of acceptability or fitness for purpose of the material tested. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address al...

  7. A simplified method for determination of radioactive iron in whole-blood samples

    DEFF Research Database (Denmark)

    Bukhave, Klaus; Sørensen, Anne Dorthe; Hansen, M.

    2001-01-01

    For studies on iron absorption in man radioisotopes represent an easy and simple tool. However, measurement of the orbital electron emitting radioiron, Fe-55, in blood is difficult and insufficiently described in the literature. The present study describes a relatively simple method for simultane...... a sensitive method for studying the intestinal absorption of Fe-55 and Fe-59 in man and at the same time allows estimation of the amount of radioiron Located in the vascular compartment.......For studies on iron absorption in man radioisotopes represent an easy and simple tool. However, measurement of the orbital electron emitting radioiron, Fe-55, in blood is difficult and insufficiently described in the literature. The present study describes a relatively simple method...... for simultaneous determination of Fe-55 and Fe-59 in blood, using a dry-ashing procedure and recrystallization of the remaining iron. The detection Limit of the method permits measurements of 0.1 Bq/ml blood thus allowing detection of Less than 1% absorption from a 40 kBq dose, which is ethically acceptable...

  8. Determination of humic substances in natural waters by cathodic stripping voltammetry of their complexes with iron.

    Science.gov (United States)

    Laglera, Luis M; Battaglia, Gianluca; van den Berg, Constant M G

    2007-09-05

    A new voltammetric method is presented for the measurement of humic substances (HS) in natural waters. The method is based on catalytic cathodic stripping voltammetry (CSV) and makes use of adsorptive properties of iron-HS complexes on the mercury drop electrode at natural pH. A fulvic acid standard (IHSS) was used to confirm the voltammetric response (peak potential and sensitivity) for the HS for natural water samples. Optimized conditions included the linear-sweep mode, deposition at -0.1 V, pH buffered at 8 and a scan rate of 50 mV s(-1). At a deposition time of 240 s in the presence of 10 nM iron and 30 mM bromate, the detection limit was 5 microg L(-1) HS in seawater, which could be lowered further by an increase in the bromate concentration, or in the adsorption time. The method was used to determine HS in the Irish Sea which were found to occur at levels between 60 and 600 microg L(-1). The new method is sufficiently sensitive to detect the low HS content in oceanic samples and has implications to the study of iron speciation.

  9. Determination of Energy Fluxes Over Agricultural Surfaces

    Directory of Open Access Journals (Sweden)

    Josefina Argete

    1994-12-01

    Full Text Available An energy budget was conducted over two kinds if surfaces: grass and corn canopy. The net radiative flux and the soil heat flux were directly measured while the latent and sensible heat flux were calculated from the vertical profiles if wet and dry-bulb temperature and wind speed. The crop storage flux was also estimated. Using the gradient or aerodynamic equations, the calculated fluxes when compared to the measured fluxes in the context of an energy budget gave an SEE = 63 Wm-2 over grass and SEE = 81 Wm-2 over corn canopy. The calculated fluxes compared reasonably well with those obtained using the Penman equations.For an energy budget research with limited instrumentation, the aerodynamic method performed satisfactorily in estimating the daytime fluxes, when atmospheric conditions are fully convective, but failed when conditions were stably stratified as during nighttime.

  10. Role of emission angular directionality in spin determination of accreting black holes with broad iron line

    CERN Document Server

    Svoboda, J; Goosmann, R W; Karas, V

    2009-01-01

    Spin of an accreting black hole can be determined by spectroscopy of the emission and absorption features produced in the inner regions of an accretion disc. We discuss the method employing the relativistic line profiles of iron in the X-ray domain, where the emergent spectrum is blurred by general relativistic effects. Precision of spectra fitting procedure could be compromised by inappropriate account of the angular distribution of the disc emission. Often a unique profile is assumed, invariable over the entire range of radii in the disc and energy in the spectral band. We study how sensitive the spin determination is to the assumptions about the intrinsic angular distribution of the emitted photons. We find that the uncertainty of the directional emission distribution translates to 20% uncertainty in determination of the marginally stable orbit. By assuming a rotating black hole in the centre of an accretion disc, we perform radiation transfer computations of an X-ray irradiated disc atmosphere to determin...

  11. Surface charge and dosage dependent potential developmental toxicity and biodistribution of iron oxide nanoparticles in pregnant CD-1 mice.

    Science.gov (United States)

    Di Bona, Kristin R; Xu, Yaolin; Ramirez, Paul A; DeLaine, Javeia; Parker, Courtney; Bao, Yuping; Rasco, Jane F

    2014-12-01

    Iron oxide nanoparticles have attracted much attention because of their potential applications, such as drug delivery, biomedical imaging, and photocatalysis. Due to their small size and the potential to cross the placental barrier, the risk to pregnant women and the developing fetus from exposure to nanoparticles is of great concern. The developmental toxicity and biodistribution of a single dose versus multiple doses of iron oxide nanoparticles with positive or negative surface charges were investigated in vivo. Multiple doses of positively-charged nanoparticles given over several days resulted in significantly increased fetal deaths and accumulation of iron in the fetal liver and placenta. These results indicate both positively and negatively charged iron oxide nanoparticles have the ability to cross the placenta and accumulate in the fetus, though greater bioaccumulation and toxicity was observed with a positively-charged surface coating.

  12. 75 FR 67395 - Iron Construction Castings From Brazil, Canada, and China; Determinations

    Science.gov (United States)

    2010-11-02

    ... COMMISSION [Investigation Nos. 701-TA-249 and 731-TA-262, 263, and 265 (Third Review)] Iron Construction... countervailing duty order on heavy iron construction castings from Brazil, the antidumping duty order on heavy iron construction castings from Canada, and the antidumping duty orders on iron construction...

  13. Determining the Effect of Environmental Conditions on Iron Corrosion by Atomic Absorption

    Science.gov (United States)

    Malel, Esteban; Shalev, Deborah E.

    2013-01-01

    Iron corrosion is a complex process that occurs when iron is exposed to oxygen and humidity and is exacerbated by the presence of chloride ions. The deterioration of iron structures or other components can be costly to society and is usually evaluated by following the properties of the corroding material. Here, the iron ions released into solution…

  14. Presence, distribution, and diversity of iron-oxidizing bacteria at a landfill leachate-impacted groundwater surface water interface

    DEFF Research Database (Denmark)

    Yu, R.; Gan, P.; Mackay, A.A.;

    2010-01-01

    We examined the presence of iron-oxidizing bacteria (IOB) at a groundwater surface water interface (GSI) impacted by reduced groundwater originating as leachate from an upgradient landfill. IOB enrichments and quantifications were obtained, at high vertical resolution, by an iron/oxygen opposing...... gradient cultivation method. The depth-resolved soil distribution profiles of water content, Fe2+, and total Fe indicated sharp gradients within the top 10 cm sediments of the GSI, where the IOB density was the highest. In addition, the vertical distribution of iron-reducing bacteria at the same sampling...

  15. Nature of Surface Changes in Stamping Tools of Gray and Ductile Cast Iron During Gas and Plasma Nitrocarburizing

    Science.gov (United States)

    Roliński, E.; Konieczny, A.; Sharp, G.

    2009-11-01

    Two cast irons, pearlitic-ferritic gray and ferritic ductile, were plasma and gas nitrocarburized at the same temperature and for the same processing time to produce a compound zone of about 10-14 μm thick. It was demonstrated that both processes caused changes in the surface roughness of the irons, and the most dramatic increase of roughness was observed after gas nitrocarburizing of the gray cast iron. It was shown that the primary reason that the results were not the same is the difference in the nitriding mechanism. Significant penetration of the surface voids and imperfections between the graphite particles and the metallic matrix by ammonia molecules led to the formation of a locally thicker compound zone and a bulging of the metallic matrix above the surface. This phenomenon did not occur in the plasma process and as a result the surface changes were much smaller than in the gas process.

  16. Emergent nesting of the Fermi surface from local-moment description of iron-pnictide high-Tc superconductors

    Science.gov (United States)

    Rodriguez, Jose P.; Araujo, Miguel A. N.; Sacramento, Pedro D.

    2014-07-01

    We uncover the low-energy spectrum of a t-J model for electrons on a square lattice of spin-1 iron atoms with 3dxz and 3dyz orbital character by applying Schwinger-boson-slave-fermion mean-field theory and by exact diagonalization of one hole roaming over a 4 × 4 × 2 lattice. Hopping matrix elements are set to produce hole bands centered at zero two-dimensional (2D) momentum in the free-electron limit. Holes can propagate coherently in the t-J model below a threshold Hund coupling when long-range antiferromagnetic order across the d + = 3d(x + iy)z and d - = 3d(x - iy)z orbitals is established by magnetic frustration that is off-diagonal in the orbital indices. This leads to two hole-pocket Fermi surfaces centered at zero 2D momentum. Proximity to a commensurate spin-density wave (cSDW) that exists above the threshold Hund coupling results in emergent Fermi surface pockets about cSDW momenta at a quantum critical point (QCP). This motivates the introduction of a new Gutzwiller wavefunction for a cSDW metal state. Study of the spin-fluctuation spectrum at cSDW momenta indicates that the dispersion of the nested band of one-particle states that emerges is electron-type. Increasing Hund coupling past the QCP can push the hole-pocket Fermi surfaces centered at zero 2D momentum below the Fermi energy level, in agreement with recent determinations of the electronic structure of mono-layer iron-selenide superconductors.

  17. Correlation between liver iron concentration determined by magnetic resonance imaging and serum ferritin in adolescents with thalassaemia disease.

    Science.gov (United States)

    Chuansumrit, Ampaiwan; Laothamathat, Jiraporn; Sirachainan, Nongnuch; Sungkarat, Witaya; Wongwerawattanakoon, Pakawan; Kumkrua, Patrapop

    2016-08-01

    MRI imaging is an alternative to serum ferritin for assessing iron overload in patients with thalassaemia disease. To correlate liver iron concentration (LIC) determined by MRI and clinical and biochemical parameters. An MRI study using cardiovascular magnetic resonance (CMR) tools to determine cardiac and liver iron was undertaken in adolescents with thalassaemia disease. Eighty-nine patients (48 males) with thalassaemia disease were enrolled. Seventy patients had been transfusion-dependent since a mean (SD) age of 3.8 (3.0) years, and 19 patients were not transfusiondependent. Mean (SD) haematocrit was 27.3 (2.9)%. Twenty-eight patients were splenectomized. Mean (SD) serum ferritin was 1673 (1506) μg/L. All transfusion-dependent patients received iron chelation at the mean (SD) age of 8.4 (3.5) years with either monotherapy of desferrioxamine, deferiprone, deferasirox or combined therapy of desferrioxamine and deferiprone, while only 5 of 19 patients who were not transfusion-dependent received oral chelation. The 89 patients underwent an MRI scan at the mean (SD) age of 14.8 (3.2) years. No patients had myocardial iron overload, but nine had severe liver iron overload, 27 had moderate liver iron overload, and 36 had mild liver iron overload. A significant correlation between liver T2* and serum ferritin was expressed as the equation: T2* (ms) = 28.080-7.629 log ferritin (μg/L) (r(2) 0.424, P = 0.0001). Patients with serum ferritin of >1000 to >2500 μg/L risked moderate and severe liver iron loading with the odds ratio ranging from 6.8 to 13.3 (95% CI 2.5-50.8). In thalassaemia, MRI is an alternative means of assessing iron stores, but when it is not available serum ferritin can be used to estimate liver T2*.

  18. Iron speciation in soft-water lakes and soils as determined by EXAFS spectroscopy and geochemical modelling

    Science.gov (United States)

    Sjöstedt, Carin; Persson, Ingmar; Hesterberg, Dean; Kleja, Dan Berggren; Borg, Hans; Gustafsson, Jon Petter

    2013-03-01

    Complexation of iron by organic matter can potentially compete with toxic metals for binding sites. Iron(III) forms both monomeric and di/trimeric complexes with fulvic and humic acids, but the nature and extent of complexation with natural organic matter samples from soft-water lakes has not been extensively studied. The aim of this study was to determine the coordination of iron in complexes with organic matter in two soft-water lakes and in the surrounding Oe soil horizons. Iron K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy was performed on particles and large colloids (>0.45 μm) collected by in-line pre-filtration, and on smaller colloids isolated both on an AGMP-1 anion-exchange column and by concentration using 1000 Da ultrafiltration. The results showed that iron(III) was mainly present in monomeric complexes with organic matter, both in the lake water smaller colloids and in the soil samples. Evidence for iron(III) (hydr)oxides was found for the lake particles, in the ultrafiltration retentates, and in some of the soils. Overall, the results suggest that complexation of iron(III) to organic matter prevents hydrolysis into polymeric forms. Strong complexation of iron(III) would lead to competition with other metals for organic-matter binding sites.

  19. Spectrophotometric determination of phosphorus in iron alloys employing a flow injection system

    Directory of Open Access Journals (Sweden)

    Gervasio Ana P. G.

    2001-01-01

    Full Text Available A flow-injection procedure for spectrophotometric determination of phosphorus in electrolytic iron and iron alloys is proposed. The method is based on the ammonium molybdate reaction followed by stannous chloride reduction in acidic medium. In order to circumvent the severe interference caused by the major constituents such as Fe(III and Cr(III, a mini-column packed with AG50W-X8 resin was coupled to the manifold. A sample throughput of 40 determinations per hour, a dynamical range from P 0.25 to 6.00 mg L-1, a reagent consumption of 25 mg ammonium molybdate and 2 mg stannous chloride per determination, and a relative standard deviation < 1% (n = 10 for a typical sample with 2.20 mg L-1 P were achieved. Three different types of samples were used to evaluate system performance. Accuracy was assessed by comparing the results with certified values and no significant difference at 95 % confidence level was observed.

  20. Selected methods for dissolved iron (II, III) and dissolved sulfide (-II) determinations in geothermal waters

    Science.gov (United States)

    Vivit, D.V.; Jenne, E.A.

    1985-01-01

    Dissolved sulfide (-II) and dissolved iron (II, III) were determined in geothermal well water samples collected at Cerro Prieto, Mexico. Most samples consisted of liquid and gas (two phases) at the instant of collection; and a subset of samples, referred to as ' flashed ' samples, consisted of pressurized steam samples which were allowed to condense. Sulfide was determined by sulfide specific ion electrode; Fe(II) and Fe(III) plus Fe(II) were determined spectrophotometrically. The precision and accuracy of the methods were evaluated for these high-silica waters with replicate analyses, spike recoveries, and an alternate method. Direct current (d.c.) argon plasma emission spectrometry was the alternate method used for Fe(III)-plus-Fe(II) analyses. Mean dissolved iron concentrations ranged from 20.2 to 834 micrograms/L (ug/L) as Fe(II) and 26.8 to 904 ug/L as Fe(III) plus Fe(II). Mean sulfide concentrations ranged from about 0.01 to 5.3 mg/L (S-II) Generally, higher S(-II) values and larger Fe(II)/Fe(III) ratios were found in the two-phase samples. These findings suggest that the ' flashed ' samples are at a less reduced state than the two-phase samples. (Author 's abstract)

  1. Enhancement in Magnetorheological Effect of Magnetorheological Elastomers by Surface Modification of Iron Particles

    Institute of Scientific and Technical Information of China (English)

    Wan-quan Jiang; Jing-jing Yao; Xing-long Gong; Lin Chen

    2008-01-01

    In order to obtain magnetorheological(MR) elastomers with high magnetorheological effect,a family of anisotropic rubber-based MR elastomers was developed using a new form of chemical modification.Three different kinds of surfactants,i.e.anionic,nonionic and compound surfactants,were employed separately to modify iron particles.The MR effect was evaluated by measuring the dynamic shear modulus of MR elastomer with a magneto-combined dynamic mechanical analyzer.Results show that the relative MR effect can be up to 188% when the iron particles are modified with 15% Span 80.Besides the surface activity of Span 80,however,such high modifying effect is partly due to the plasticizing effect of Span 80.Compared with the single surfactant,the superior surface activity of compound surfactant makes the relative MR effect reach 77% at a low content of 0.4%.Scanning electron microscope observation shows that the modification of compound surfactant results in perfect compatibility between particles and rubber matrix and special self-assembled structure of particles.Such special structure has been proved beneficial to the improvement of the relative MR effect.

  2. Facile fabrication of iron-based superhydrophobic surfaces via electric corrosion without bath

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Qinghe [College of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Liu, Hongtao, E-mail: liuht100@126.com [College of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Chen, Tianchi [College of Mechanical & Electrical Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Wei, Yan; Wei, Zhu [College of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China)

    2016-04-30

    carbon steel substrate under appropriate process; the contact angle of the as-prepared superhydrophobic surface can be up to 152 ± 0.5°, and the sliding angle is 1–2°; its anti-corrosion property, anti-icing performance and the friction property all show an excellent level. This method provides the possibility of industrialization of superhydrophobic surface based on iron substrate as it can prepare massive superhydrophobic surface quickly.

  3. Mathematical modeling of localized melting around graphite nodules during laser surface hardening of austempered ductile iron

    Science.gov (United States)

    Roy, A.; Manna, I.

    2000-10-01

    An attempt has been made to mathematically predict the optimum conditions of laser surface hardening (LSH) of austempered ductile iron (ADI) that can ensure a predominantly martensitic microstructure and preclude partial/complete dissolution of graphite nodules in the laser hardened zone during laser irradiation. The exercise involves prediction of the thermal profile (using the Ashby and Easterling model), and consequently, the carbon diffusion profile around the graphite nodules at different depths from the surface for the given conditions of LSH. Microstructural investigations have been carried out by optical and scanning electron microscopy to study the morphology, shape and width of the partially/completely melted graphite nodules as a function of the LSH parameters. Finally, the predicted maximum width of the melted zone around the graphite nodules is compared with the relevant experimental data to validate the proposed model.

  4. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    Energy Technology Data Exchange (ETDEWEB)

    Sodipo, Bashiru Kayode, E-mail: bashirsodipo@gmail.com [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Aziz, Azlan Abdul [School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang (Malaysia)

    2016-10-15

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION. - Highlights: • We present recent advances in synthesis of SPION and various routes of producing silica coated SPION • The synthetic routes of producing SPION can be classified into three: physical, chemical and biological methods. • The chemical method is the most cited method of producing SPION and it sub-classified into liquid and gas phase. • The techniques of producing silica coated SPION is grouped into seeded and non-seeded methods.

  5. Effects of surface condition on aqueous corrosion and environmental embrittlement of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, R.L.; Buchanan, R.A. [Univ. of Tennessee, Knoxville, TN (United States)

    1996-08-01

    Effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion and environmental-embrittlement characteristics of Fe{sub 3}Al-based iron aluminides (FA-84, FA-129 and FAL-Mo), a FeAl-based iron aluminide (FA-385), and a disordered low-aluminum Fe-Al alloy (FAPY) were evaluated. All tests were conducted at room temperature in a mild acid-chloride solution. In cyclic-anodic-polarization testing for aqueous-corrosion behavior, the surface conditions examined were: as-received (i.e., with the retained high-temperature oxides), mechanically cleaned and chemically cleaned. For all materials, the polarization tests showed the critical pitting potentials to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. These results indicate detrimental effects of the retained high-temperature oxides in terms of increased susceptibilities to localized corrosion. In 200-hour U-bend stress-corrosion-cracking tests for environmental-embrittlement behavior, conducted at open-circuit corrosion potentials and at a hydrogen-charging potential of {minus}1500 mV (SHE), the above materials (except FA-385) were examined with retained oxides and with mechanically cleaned surfaces. At the open-circuit corrosion potentials, none of the materials in either surface condition underwent cracking. At the hydrogen-charging potential, none of the materials with retained oxides underwent cracking, but FA-84, FA-129 and FAL-Mo in the mechanically cleaned condition did undergo cracking. These results suggest beneficial effects of the retained high-temperature oxides in terms of increased resistance to environmental hydrogen embrittlement.

  6. A Simple Spectrofluorimetric Method Based on Quenching of a Nickel(II)-Phthalocyanine Complex to Determine Iron (III).

    Science.gov (United States)

    Çağlar, Yasemin; Saka, Ece Tuğba; Alp, Hakan; Kantekin, Halit; Ocak, Ümmühan; Ocak, Miraç

    2016-07-01

    A new nickel(II)-phthalocyanine complex (NiPc) was synthesized and used as a fluorescent ligand in determination of iron in real samples. The NiPc compound, when excited at 350 nm, decreases of emission with increases of the iron(III) concentration at 425 nm were used analytical response in a modified standard addition method. The method was validated by analyzing two certified reference materials (CRM-SA-C Sandy Soil C and Mixed Polish Herbs (INCT-MPH-2). Food and drug samples were digested in a closed microwave system using nitric acid and hydrogen peroxide. Therefore, all iron in the samples converted to iron(III) ion. These solutions were used directly in determination of iron(III) ion. No cleanup or enrichment of the solutions was required. The calibration graph was linear until 14.00 μg mL(-1). Detection limit and quantification limit were 1.29 μg mL(-1) and 3.88 μg mL(-1), respectively. The method provided accurate results for the majority of the food samples tested, including spanich, dill, mint, purslane, rocket, red lentils, dry beans and two iron medicinal tablets. Also, the high recovery (95.6 %) was obtained for a fortified stream water sample. The simple and cost-effective method is suitable for monitoring total iron concentration in foods and drug samples.

  7. Microstructure of Ni / WC Surface Composite Layer on Gray Iron Substrate

    Institute of Scientific and Technical Information of China (English)

    YANG Guirong; SONG Wenming; MA Ying; LU Jinjun; HAO Yuan; LI Yuandong; WANG Haitang

    2011-01-01

    The surface infiltrated composite (Ni/WC) layers on gray iron substrate were fabricated through a vacuum infiltration casting technique (VICT) using Ni-based composite powder with different WC particles content as raw materials.The microstructures of surface infiltrated composite layer,the interface structures between surface composite layer and the substrate,the changes of macro-hardness with the increasing of WC content and the micro-hardness distribution are investigated.The infiltrated composite layer includes a surface composite layer and a transition layer,and the thickness of the transition layer decreases with the increasing content of WC.The thickness of transition layer with 20%WC content in the surface infiltrated composite layer was 170 μrn which was the thickest for all transition layers with different WC content.The surface composite layer was mainly composed of WC,W2C,FeB and NiB,along with Ni-Cr-Fe,Ni (Cr) solid solution,Ni (Si) solid solution and Ni (Fe) solid solution.The transition layer was composed of Ni (Cr) solid solution,Ni (Fe) solid solution,Ni (Si) solid solution,Fe (Ni) solid solution and eutectic.The surface macrohardness and micro-hardness of the infiltrated layer had been evaluated.The macro-hardness of the surface composite layer decreases with the WC content increasing,and the average macro-hardness is HRC60.The distribution of micro-hardness presents gradient change.The average micro-hardness of the infiltrated layer is about HV 1000.

  8. EFFECT OF TOOL NOSE RADIUS AND CUTTING PARAMETERS ON TOOL LIFE, SURFACE ROUGHNESS IN TURNING OF GREY CAST IRON

    Directory of Open Access Journals (Sweden)

    Prasanna P Kulkarni

    2014-03-01

    Full Text Available In metal cutting industries peoples are trying to reduce the cost of the production by proper selection of inserts, tool geometry, and cutting conditions to obtain economical benefits. Tool nose radius has significant influence on tool life and surface finish. The aim of this research is to investigate the effect of tool nose radius under different cutting conditions and their effect on tool life, surface roughness. The measurement has been carried out by rough boring operation using grey cast iron cylinder liners at three cutting speed (Vc and feed rate (f. Depth of cut (doc is kept constant at 2.5mm.Cutting tool used in this work is multilayer coated tool of nose radius 0.8mm and 1.2mm nose radius. Tool coated with titanium nitride (TiN + titanium carbo nitride (TiCN +Aluminium oxide (Al2O3 coating. The insert is designated with SNMG 120408. Cutting conditions used is speed (Vc 100m/min, 125m/min and 150m/min. Feed rate (f 0.20mm/rev,0.23mm/rev,0.27mm/rev.Finally results of the present work determine the appropriate parameter for increasing the tool life and surface finish for two different nose radius tools.

  9. Effect of different iron forms on iron plaque on root surface and iron uptake in rice seedlings%不同铁形态对水稻根表铁膜及铁吸收的影响

    Institute of Scientific and Technical Information of China (English)

    傅友强; 梁建平; 于智卫; 吴道铭; 蔡昆争; 沈宏

    2011-01-01

    Iron forms have great impacts on iron nutrition of rice seedlings, however, it remains unclear on how different iron forms influence iron uptake in rice seedlings. In this study, a hydroponic experiment was conducted to investigate the effects of FeCl2 and FeCl3 on iron uptake and iron plaque in rice seedlings. Results showed that the concentration of iron plaque on root surface under FeCl2 treatment was 197%-233% of that under FeCl3 treatment. Fe3^+ and Fe2^+ consisted of 85%-92% and 8%-15% of the total iron plaque respectively. The concentration of iron plaque on the root surface of Tianyou 998 ( Oryza sativa L. cv. TY998 ) was significantly higher than that in Peizataifeng (Oryza sativa L. cv. PZTF). Iron uptake in TY998 was 115%-138% of that in PZTF. Treatment with FeCl2 increased the activity of rice roots by 24%-69%, while FeCl3 treatment by 16%-54%. The activities of SOD,POD and CAT in rice roots were increased by 11%-32%, 15%-30% and 30%-31% respectively under FeCl2 treatment, while they did not change obviously under FeCl3 treatment. The above results suggested that the addition of a certain concentration of iron enhanced the formation of iron plaque on root surface and iron uptake in rice seedlings. In comparison to FeCl3 treatment, FeCl2 treatment was conductive to the increase of activities of antioxidant enzymes, thus improved iron uptake in rice seedlings.%通过溶液培养试验研究了FeCl2·4H2O和FeCl3·6H2O对水稻根表铁膜数量及铁吸收的影响。结果表明,FeCl2处理时水稻根表铁膜浓度是FeCl3处理的197%~233%。利用EDTA—BPDS对铁膜形态分析看出,根表铁膜中Fe^3+占85%~92%,Fe2^占8%~15%。水稻天优998(TY998)根表铁膜数量显著高于培杂泰丰(PzTF),其铁吸收是培杂泰丰的115%~138%。两种铁形态处理明显提高了水稻的根系活力,其中,FeCl2处理时水稻根系活力增加24%~69%,FeCl3为16%~54%。FeCl2处

  10. Reduction-induced inward diffusion and crystal growth on the surfaces of iron-bearing silicate glasses

    DEFF Research Database (Denmark)

    Liu, S.J.; Tao, H.Z.; Zhang, Y.F.

    2015-01-01

    We investigate the sodium inward diffusion (i.e., sodium diffusion from surface toward interior) in iron containing alkaline earth silicate glasses under reducing conditions around Tg and the induced surface crystallization. The surface crystallization is caused by formation of a silicate-gel layer...... first and then the growth of silica crystals on the glass surface. The type of alkaline earth cations has a strong impact on both the glass transition and the surface crystallization. In the Mg-containing glass, a quartz layer forms on the glass surface. This could be attributed to the fact that Mg2...

  11. Correlation between surface physicochemical properties and the release of iron from stainless steel AISI 304 in biological media.

    Science.gov (United States)

    Hedberg, Yolanda; Karlsson, Maria-Elisa; Blomberg, Eva; Odnevall Wallinder, Inger; Hedberg, Jonas

    2014-10-01

    Stainless steel is widely used in biological environments, for example as implant material or in food applications, where adsorption-controlled ligand-induced metal release is of importance from a corrosion, health, and food safety perspective. The objective of this study was to elucidate potential correlations between surface energy and wettability of stainless steel surfaces and the release of iron in complexing biological media. This was accomplished by studying changes in surface energies calculated from contact angle measurements, surface oxide composition (X-ray photoelectron spectroscopy), and released iron (graphite furnace atomic absorption spectroscopy) for stainless steel grade AISI 304 immersed in fluids containing bovine serum albumin or citric acid, and non-complexing fluids such as NaCl, NaOH, and HNO3. It was shown that the surface wettability and polar surface energy components were all influenced by adventitious atmospheric carbon (surface contamination of low molecular weight), rather than differences in surface oxide composition in non-complexing solutions. Adsorption of both BSA and citrate, which resulted in ligand-induced metal release, strongly influenced the wettability and the surface energy, and correlated well with the measured released amount of iron.

  12. The Effects of Magnetic Field Morphology on the Determination of Oxygen and Iron Abundances in the Solar Photosphere

    Science.gov (United States)

    Moore, Christopher S.; Uitenbroek, Han; Rempel, Matthias; Criscuoli, Serena; Rast, Mark

    2016-01-01

    The solar chemical abundance (or a scaled version of it) is implemented in numerous astrophysical analyses. Thus, an accurate and precise estimation of the solar elemental abundance is crucial in astrophysics.We have explored the impact of magnetic fields on the determination of the solar photospheric oxygen andiron abundances using 3D radiation-magnetohydrodynamic (MHD) simulations of convection. Specifically, weexamined differences in abundance deduced from three classes of atmospheres simulated with the MURaM code: apure hydrodynamic (HD) simulation, an MHD simulation with a local dynamo magnetic field that has saturated withan unsigned vertical field strength of 80 G at the optical depth unity surface, and an MHD simulation with an initially imposed vertical mean field of 80 G. We use differential equivalent width analysis for diagnosing abundances derived from five oxygen and four iron spectral lines of differing wavelength, oscillator strength, excitation potential, and Lande g-factor, and find that the morphology of the magnetic field is important to the outcome of abundance determinations. The largest deduced abundance differences are found in the vertical mean field simulations and small scale unresolved field resulting from the local dynamo has a smaller impact on abundance determinations.

  13. An iron detection system determines bacterial swarming initiation and biofilm formation

    NARCIS (Netherlands)

    Lin, Chuan-Sheng; Tsai, Yu-Huan; Chang, Chih-Jung; Tseng, Shun-Fu; Wu, Tsung-Ru; Lu, Chia-Chen; Wu, Ting-Shu; Lu, Jang-Jih; Horng, Jim-Tong; Martel, Jan; Ojcius, David M.; Lai, Hsin-Chih; Young, John D.; Andrews, S. C.; Robinson, A. K.; Rodriguez-Quinones, F.; Touati, D.; Yeom, J.; Imlay, J. A.; Park, W.; Marx, J. J.; Braun, V.; Hantke, K.; Cornelis, P.; Wei, Q.; Vinckx, T.; Troxell, B.; Hassan, H. M.; Verstraeten, N.; Lewis, K.; Hall-Stoodley, L.; Costerton, J. W.; Stoodley, P.; Kearns, D. B.; Losick, R.; Butler, M. T.; Wang, Q.; Harshey, R. M.; Lai, S.; Tremblay, J.; Deziel, E.; Overhage, J.; Bains, M.; Brazas, M. D.; Hancock, R. E.; Partridge, J. D.; Kim, W.; Surette, M. G.; Givskov, M.; Rather, P. N.; Houdt, R. Van; Michiels, C. W.; Mukherjee, S.; Inoue, T.; Frye, J. G.; McClelland, M.; McCarter, L.; Silverman, M.; Matilla, M. A.; Wu, Y.; Outten, F. W.; Singh, P. K.; Parsek, M. R.; Greenberg, E. P.; Welsh, M. J.; Banin, E.; Vasil, M. L.; Wosten, M. M.; Kox, L. F.; Chamnongpol, S.; Soncini, F. C.; Groisman, E. A.; Laub, M. T.; Goulian, M.; Krell, T.; Lai, H. C.; Lin, C. S.; Soo, P. C.; Tsai, Y. H.; Wei, J. R.; Wyckoff, E. E.; Mey, A. R.; Leimbach, A.; Fisher, C. F.; Payne, S. M.; Livak, K. J.; Schmittgen, T. D.; Clarke, M. B.; Hughes, D. T.; Zhu, C.; Boedeker, E. C.; Sperandio, V.; Stintzi, A.; Clarke-Pearson, M. F.; Brady, S. F.; Drake, E. J.; Gulick, A. M.; Qaisar, U.; Rowland, M. A.; Deeds, E. J.; Garcia, C. A.; Alcaraz, E. S.; Franco, M. A.; Rossi, B. N. Passerini de; Mehi, O.; Skaar, E. P.; Visaggio, D.; Nishino, K.; Dietz, P.; Gerlach, G.; Beier, D.; Bustin, S. A.; Schwyn, B.; Neilands, J. B.

    2016-01-01

    Iron availability affects swarming and biofilm formation in various bacterial species. However, how bacteria sense iron and coordinate swarming and biofilm formation remains unclear. Using Serratia marcescens as a model organism, we identify here a stage-specific iron-regulatory machinery comprising

  14. An iron detection system determines bacterial swarming initiation and biofilm formation

    NARCIS (Netherlands)

    Lin, Chuan-Sheng; Tsai, Yu-Huan; Chang, Chih-Jung; Tseng, Shun-Fu; Wu, Tsung-Ru; Lu, Chia-Chen; Wu, Ting-Shu; Lu, Jang-Jih; Horng, Jim-Tong; Martel, Jan; Ojcius, David M.; Lai, Hsin-Chih; Young, John D.; Andrews, S. C.; Robinson, A. K.; Rodriguez-Quinones, F.; Touati, D.; Yeom, J.; Imlay, J. A.; Park, W.; Marx, J. J.; Braun, V.; Hantke, K.; Cornelis, P.; Wei, Q.; Vinckx, T.; Troxell, B.; Hassan, H. M.; Verstraeten, N.; Lewis, K.; Hall-Stoodley, L.; Costerton, J. W.; Stoodley, P.; Kearns, D. B.; Losick, R.; Butler, M. T.; Wang, Q.; Harshey, R. M.; Lai, S.; Tremblay, J.; Deziel, E.; Overhage, J.; Bains, M.; Brazas, M. D.; Hancock, R. E.; Partridge, J. D.; Kim, W.; Surette, M. G.; Givskov, M.; Rather, P. N.; Houdt, R. Van; Michiels, C. W.; Mukherjee, S.; Inoue, T.; Frye, J. G.; McClelland, M.; McCarter, L.; Silverman, M.; Matilla, M. A.; Wu, Y.; Outten, F. W.; Singh, P. K.; Parsek, M. R.; Greenberg, E. P.; Welsh, M. J.; Banin, E.; Vasil, M. L.; Wosten, M. M.; Kox, L. F.; Chamnongpol, S.; Soncini, F. C.; Groisman, E. A.; Laub, M. T.; Goulian, M.; Krell, T.; Lai, H. C.; Lin, C. S.; Soo, P. C.; Tsai, Y. H.; Wei, J. R.; Wyckoff, E. E.; Mey, A. R.; Leimbach, A.; Fisher, C. F.; Payne, S. M.; Livak, K. J.; Schmittgen, T. D.; Clarke, M. B.; Hughes, D. T.; Zhu, C.; Boedeker, E. C.; Sperandio, V.; Stintzi, A.; Clarke-Pearson, M. F.; Brady, S. F.; Drake, E. J.; Gulick, A. M.; Qaisar, U.; Rowland, M. A.; Deeds, E. J.; Garcia, C. A.; Alcaraz, E. S.; Franco, M. A.; Rossi, B. N. Passerini de; Mehi, O.; Skaar, E. P.; Visaggio, D.; Nishino, K.; Dietz, P.; Gerlach, G.; Beier, D.; Bustin, S. A.; Schwyn, B.; Neilands, J. B.

    2016-01-01

    Iron availability affects swarming and biofilm formation in various bacterial species. However, how bacteria sense iron and coordinate swarming and biofilm formation remains unclear. Using Serratia marcescens as a model organism, we identify here a stage-specific iron-regulatory machinery comprising

  15. Determination of Land Surface Temperature (LST) and Potential ...

    African Journals Online (AJOL)

    Determination of Land Surface Temperature (LST) and Potential Urban Heat Island Effect in Parts of Lagos State using Satellite ... Changes in temperature appear to be closely related to concentrations of atmospheric carbon dioxide.

  16. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    Energy Technology Data Exchange (ETDEWEB)

    Arya, S. P.; Mahajan, M. [Haryana, Kurukshetra Univ. (India). Dept. of Chemistry

    1998-05-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 {mu}g ml{sup -1}. Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C. [Italiano] Si propone un rapido e semplice metodo spettrofotometrico per la determinazione dell`acido ascorbico. L`acido ascorbico riduce il ferro(III) a ferro(II) che forma con la dimetilgliossima, in presenza di piridina, un complesso colorato in rosso. L`assorbanza della soluzione risultante e` misurata a 514 nm e si ottiene una relazione lineare tra assorbanza e concentrazione dell`acido ascorbico fino a 14 {mu}g ml{sup -1}. Si sono condotti studi sugli interferenti usualmente associati all`acido ascorbico ed e` stata valutata l`applicabilita` del metodo all`analisi di preparati farmaceutici di vitamina C.

  17. Optimization of Reactive Blue 21 removal by Nanoscale Zero-Valent Iron using response surface methodology

    Directory of Open Access Journals (Sweden)

    Mahmood Reza Sohrabi

    2016-07-01

    Full Text Available Since Reactive Blue 21 (RB21 is one of the dye compounds which is harmful to human life, a simple and sensitive method to remove this pollutant from wastewater is using Nano Zero-Valent Iron (NZVI catalyst. In this paper, a Central Composite Rotatable Design (CCRD was employed for response surface modeling to optimize experimental conditions of the RB21 removal from aqueous solution. The significance and adequacy of the model were analyzed using analysis of variance (ANOVA. Four independent variables—including catalyst amount (0.1–0.9 g, pH (3.5–9.5, removal time (30–150 s and dye concentration (10–50 mg/L—were transformed to coded values and consequently second order quadratic model was built to predict the responses. The result showed that under optimized experimental conditions the removal of RB21 was over 95%.

  18. Laser Surface Remelting of Medium Ni-Cr Infinite Chilling Cast Iron Roll

    Institute of Scientific and Technical Information of China (English)

    YAO Jian-hua; ZHANG Qun-li; XIE Song-jing

    2004-01-01

    Laser surface remelting of medium Ni-Cr infinite chilling cast iron was performed with a continuous wave CO2 laser beam with the power of 7 KW under the argon shielding. The microstructural analysis of the laser remelted layer by optical microscope shows that the laser remelted layer consists of three zones, which is the melting zone, the transition zone and the heat affected zone. The size of the dendrite of the melting zone is only in the 1/10 to 1/30 range of that of the substrate. The distribution of the hardness of the laser remelted layer was detected, and the carrying capacity of rolling steel was also field-tested. The results show that both the hardness of the remelted layer and the carrying capacity all increase,especially, the carrying capacity was 50% increased compared with the substrate.

  19. Laser Surface Remelting of Medium Ni-Cr Infinite Chilling Cast Iron Roll

    Institute of Scientific and Technical Information of China (English)

    YAOJian-hua; ZHANGQun-li; XIESong-jing

    2004-01-01

    Laser surface remelting of medium Ni-Cr infinite chilling cast iron was performed with a continuous wave CO2 laser beam with the power of 7 KW under the argon shielding. The microstructural analysis of the laser remelted layer by optical microscope shows that the laser remelted layer consists of three zones, which is the melting zone, the transition zone and the heat affected zone. The size of the dendrite of the melting zone is only in the 1/10 to 1/30 range of that of the substrate. The distribution of the hardness of the laser remelted layer was detected, and the carrying capacity of rolling steel was also field-tested. The results show that both the hardness of the remelted layer and the carrying capacity all increase, especially, the carrying capacity was 50% increased compared with the substrate.

  20. On the nature of inhibition performance of imidazole on iron surface

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Juliana O.; Silva, Edilson C. da [Instituto de Quimica, Departamento de Fisico-Quimica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, CT Bloco A. Rio de Janeiro, 21941-909 Rio de Janeiro (Brazil); Rocha, Alexandre B., E-mail: rocha@iq.ufrj.br [Instituto de Quimica, Departamento de Fisico-Quimica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, CT Bloco A. Rio de Janeiro, 21941-909 Rio de Janeiro (Brazil)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Imidazole corrosion inhibition performance. Black-Right-Pointing-Pointer Slab model and periodic DFT. Black-Right-Pointing-Pointer Cooperative effect on adsorption. Black-Right-Pointing-Pointer Polymerization of imidazole molecules at high coverage. Black-Right-Pointing-Pointer Protective film. - Abstract: Quantum mechanical calculations based on the Density Functional Theory under periodic boundary conditions were used to construct a model for the inhibition performance of imidazole on iron surface. It is shown that, at high coverage, imidazole molecules form C-C intermolecular bonds creating a protective film, which constitutes a hydrophobic medium and, consequently, prevents adsorption of water molecules. The establishment of intermolecular bonds leads to a stabilization of the adsorption energy and this cooperative effect is the thermodynamic explanation for the film formation. These results also point out to the limitation of previous studies based on properties of isolated inhibitor molecules.

  1. Correlation between serum ferritin levels and liver iron concentration determined by MR imaging: impact of hematologic disease and inflammation.

    Science.gov (United States)

    Olthof, Allard W; Sijens, Paul E; Kreeftenberg, Herman G; Kappert, Peter; Irwan, Roy; van der Jagt, Eric J; Oudkerk, Matthijs

    2007-02-01

    Liver iron concentration was determined in 28 patients by magnetic resonance imaging using the method of Gandon et al. (Non-invasive assessment of hepatic iron stores by MRI. Lancet 2004;363:357-362). The result showed a significant correlation with blood plasma ferritin content (Spearman's r=.66; P<.001) and a slightly improving correlation coefficient when limited to those patients not known to have inflammation (r=.82; n=17; P<.001). Zooming in on patients with hematologic disease also had a beneficial effect on the correlation between liver iron content and plasma ferritin level (r=.79; n=13; P=.001). It is concluded that in patients without inflammation and in patients with hematologic disease, the content of ferritin in blood is a better predictor of liver iron content than in other patient categories.

  2. Effect of iron and phosphate on bacterial cyanide formation determined by methemoglobin in two-dimensional gradient microcultivations.

    Science.gov (United States)

    Rudolf von Rohr, Matthias; Furrer, Gerhard; Brandl, Helmut

    2009-10-01

    Cyanide formation by microorganisms is typically observed during early stationary growth phase and is facilitated by the presence of iron(III) and inorganic phosphate. Extracellular free cyanide in aqueous solutions might readily react with methemoglobin added and can be determined by UV/VIS spectroscopy. As alternative to existing methods, this provided the basis for an analytical method which has not been used previously for the determination of cyanide in bacterial cultivations. We successfully applied the technique to study the combined effect of both iron(III) and phosphate on the cyanide formation by Pseudomonas fluorescens, which we used as model organism known for its ability to form HCN. Information on the combined effect of iron and phosphate was obtained by using commercially available 24-well microtiter plates as two-dimensional gradient systems. After its reaction with methemoglobin, cyanide was measured reproducibly at the wavelength of 427 nm. We found a combined effect of both iron and phosphate. In the absence of inorganic phosphate, cyanide formation was stimulated considerably by increasing concentrations of iron(III), although the effect on the bacterial growth of P. fluorescens was almost insignificant. This suggests that iron is more important than inorganic phosphate for the cyanogenesis by P. fluorescens.

  3. Surface water iron supplies in the Southern Ocean sustained by deep winter mixing

    CSIR Research Space (South Africa)

    Tagliabue, A

    2014-04-01

    Full Text Available Low levels of iron limit primary productivity across much of the Southern Ocean. At the basin scale, most dissolved iron is supplied to surfacewaters from subsurface reservoirs, because land inputs are spatially limited. Deep mixing in winter...

  4. Biomaterial surface proteomic signature determines interaction with epithelial cells.

    Science.gov (United States)

    Abdallah, Mohamed-Nur; Tran, Simon D; Abughanam, Ghada; Laurenti, Marco; Zuanazzi, David; Mezour, Mohamed A; Xiao, Yizhi; Cerruti, Marta; Siqueira, Walter L; Tamimi, Faleh

    2017-03-01

    Cells interact with biomaterials indirectly through extracellular matrix (ECM) proteins adsorbed onto their surface. Accordingly, it could be hypothesized that the surface proteomic signature of a biomaterial might determine its interaction with cells. Here, we present a surface proteomic approach to test this hypothesis in the specific case of biomaterial-epithelial cell interactions. In particular, we determined the surface proteomic signature of different biomaterials exposed to the ECM of epithelial cells (basal lamina). We revealed that the biomaterial surface chemistry determines the surface proteomic profile, and subsequently the interaction with epithelial cells. In addition, we found that biomaterials with surface chemistries closer to that of percutaneous tissues, such as aminated PMMA and aminated PDLLA, promoted higher selective adsorption of key basal lamina proteins (laminins, nidogen-1) and subsequently improved their interactions with epithelial cells. These findings suggest that mimicking the surface chemistry of natural percutaneous tissues can improve biomaterial-epithelial integration, and thus provide a rationale for the design of improved biomaterial surfaces for skin regeneration and percutaneous medical devices.

  5. Effects of surface chemistry and size on iron oxide nanoparticle delivery of oligonucleotides

    Science.gov (United States)

    Shen, Christopher

    The discovery of RNA interference and the increasing understanding of disease genetics have created a new class of potential therapeutics based on oligonucleotides. This therapeutic class includes antisense molecules, small interfering RNA (siRNA), and microRNA modulators such as antagomirs (antisense directed against microRNA) and microRNA mimics, all of which function by altering gene expression at the translational level. While these molecules have the promise of treating a host of diseases from neurological disorders to cancer, a major hurdle is their inability to enter cells on their own, where they may render therapeutic effect. Nanotechnology is the engineering of materials at the nanometer scale and has gained significant interest for nucleic acid delivery due to its biologically relevant length-scale and amenability to multifunctionality. While a number of nanoparticle vehicles have shown promise for oligonucleotide delivery, there remains a lack of understanding of how nanoparticle coating and size affect these delivery processes. This dissertation seeks to elucidate some of these factors by evaluating oligonucleotide delivery efficiencies of a panel of iron oxide nanoparticles with varying cationic coatings and sizes. A panel of uniformly-sized nanoparticles was prepared with surface coatings comprised of various amine groups representing high and low pKas. A separate panel of nanoparticles with sizes of 40, 80, 150, and 200 nm but with the same cationic coating was also prepared. Results indicated that both nanoparticle surface coating and nanoparticle hydrodynamic size affect transfection efficiency. Specific particle coatings and sizes were identified that gave superior performance. The intracellular fate of iron oxide nanoparticles was also tracked by electron microscopy and suggests that they function via the proton sponge effect. The research presented in this dissertation may aid in the rational design of improved nanoparticle delivery vectors for

  6. Effect of surface condition on the aqueous corrosion behavior of iron aluminies

    Energy Technology Data Exchange (ETDEWEB)

    Buchanan, R.A.; Perrin, R.L. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-08-01

    The effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion characteristics of Fe-Al-based alloys were evaluated by electrochemical methods. Cyclic anodic polarization evaluations were conducted at room temperature in a mild acid-chloride solution (pH = 4,200 ppm Cl{sup {minus}}) on the Fe{sub 3}Al-based iron aluminides, FA-84 (Fe-28Al-2Cr-0.05B, at %), FA-129 (Fe-28Al-5Cr-0.5Nb-0.2C, at %), and FAL-Mo (Fe-28Al-5Cr-1Mo-0.04B-0.08Zr, at %), on the FeAl-based iron aluminide, FA-385 (Fe-35.65Al-0.20Mo-0.05Zr-0.11C, at %). The surface conditions evaluated were: As received (i.e. with the retained high-temperature oxides), mechanically cleaned (ground through 600-grit SiC paper), and chemically cleaned (10% HNO{sub 3}, 2%HF, at 43 {degree}C). The principal electrochemical parameter of interest was the critical putting potential with lower values indicating less resistance to chloride-induced localized corrosion. For all materials evaluated, the critical pitting potential was found to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. Mechanisms responsible for the detrimental high-temperature-oxide effect are under study.

  7. Study of high cycle fatigue of PVD surface-modified austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Feng, H.P.; Lee, S.C.; Hsu, C.H.; Ho, J.M. [Tatung Inst. of Technol., Taipei (Taiwan, Province of China). Dept. of Mater. Eng.

    1999-05-25

    Austempered ductile iron (ADI) is made from ductile iron by an austempering treatment, and its main microstructure is ausferrite that is composed of acicular ferrite and high carbon austenite. The purpose of this experiment is to investigate the influence of different coating layers and the size of casting (mass effect) on the high-cycle fatigue properties of ADI. Specimens in two casting sizes of the same chemical composition were subjected to a high-toughness austempering treatment, then coated with TiN or TiCN hard films by a physical vapor deposition (PVD) process. The results showed that the fatigue limit of the small casting size ADI is 292 MPa for ADI coated with TiN and 306 MPa for ADI coated with TiCN, which are 16% and 22%, respectively, higher than that of the ADI without coating (251 MPa). For the large casting size ADI, the fatigue limits are 200, 214 and 217 MPa for ADI without coating, ADI coated with TiN and ADI coated with TiCN, respectively. ADI coated with TiN and with TiCN are 7% and 9% better than the uncoated. Thus, it is concluded that TiN and TiCN coatings by PVD can improve the high-cycle fatigue strength of ADI. This is due to the high surface hardness and possibly the ADI surface compressive residual stress as well. For the small casting size ADI, TiCN-coated specimens have a bit higher fatigue strengths and this might be attributed to the higher hardness of TiCN than TiN films. As to the effect of mass, it is found that the small casting size has better fatigue properties and benefits more from the coating films. This could have stemmed from the higher nodule count and its associated benefits in thinner castings. (orig.) 24 refs.

  8. Horizontal gradient of the chemical speciation of iron in surface waters of the northeast Atlantic Ocean

    NARCIS (Netherlands)

    Boye, Marie; Aldrich, Annette P.; Berg, Constant M.G. van den; Jong, Jeroen T.M. de; Veldhuis, Marcel; Baar, Hein J.W. de

    2003-01-01

    A transect across the eastern North Atlantic from 42°N, 23°W towards the European continental shelf and English Channel shows a gradient of increasing concentrations of dissolved iron (0.7–1.9 nM), iron-binding ligands and iron(II) across the continental rise. Other data, notably aluminium and manga

  9. Research of polishing process to control the iron contamination on the magnetorheological finished KDP crystal surface.

    Science.gov (United States)

    Chen, Shaoshan; Li, Shengyi; Peng, Xiaoqiang; Hu, Hao; Tie, Guipeng

    2015-02-20

    A new nonaqueous and abrasive-free magnetorheological finishing (MRF) method is adopted for processing a KDP crystal. MRF polishing is easy to result in the embedding of carbonyl iron (CI) powders; meanwhile, Fe contamination on the KDP crystal surface will affect the laser induced damage threshold seriously. This paper puts forward an appropriate MRF polishing process to avoid the embedding. Polishing results show that the embedding of CI powders can be avoided by controlling the polishing parameters. Furthermore, on the KDP crystal surface, magnetorheological fluids residua inevitably exist after polishing and in which the Fe contamination cannot be removed completely by initial ultrasonic cleaning. To solve this problem, a kind of ion beam figuring (IBF) polishing is introduced to remove the impurity layer. Then the content of Fe element contamination and the depth of impurity elements are measured by time of flight secondary ion mass spectrometry. The measurement results show that there are no CI powders embedding in the MRF polished surface and no Fe contamination after the IBF polishing process, respectively. That verifies the feasibility of MRF polishing-IBF polishing (cleaning) for processing a KDP crystal.

  10. Using Iron-Manganese Co-Oxide Filter Film to Remove Ammonium from Surface Water

    Directory of Open Access Journals (Sweden)

    Ruifeng Zhang

    2017-07-01

    Full Text Available An iron-manganese co-oxide filter film (MeOx has been proven to be a good catalyst for the chemical catalytic oxidation of ammonium in groundwater. Compared with groundwater, surface water is generally used more widely and has characteristics that make ammonium removal more difficult. In this study, MeOx was used to remove ammonium from surface water. It indicated that the average ammonium removal efficiency of MeOx was greater than 90%, even though the water quality changed dramatically and the water temperature was reduced to about 6–8 °C. Then, through inactivating microorganisms, it showed that the removal capability of MeOx included both biological (accounted for about 41.05% and chemical catalytic oxidation and chemical catalytic oxidation (accounted for about 58.95%. The investigation of the characterizations suggested that MeOx was formed by abiotic ways and the main elements on the surface of MeOx were distributed homogenously. The analysis of the catalytic oxidation process indicated that ammonia nitrogen may interact with MeOx as both ammonia molecules and ammonium ions and the active species of O2 were possibly •O and O2−.

  11. MRI of transplanted surface-labeled pancreatic islets with heparinized superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Jung, Min Jin; Lee, Seung Soo; Hwang, Yong Hwa; Jung, Hae Song; Hwang, Jin Wook; Kim, Min Jun; Yoon, Sangwoo; Lee, Dong Yun

    2011-12-01

    Transplantation of insulin-secreting pancreatic islets can provide real-time regulation of blood glucose in patients with type 1 diabetes mellitus. Currently, noninvasive and repetitive monitoring of islet engraftment and function is an emerging and promising modality for successful islet transplantation. Here we report a new technique for highly sensitive in vivo magnetic resonance (MR) imaging of transplanted pancreatic islets. To this end, heparinized superparamagnetic iron oxide (heparin-SPIO) nanoparticle was newly synthesized for chemical conjugation onto islet surface. Compared to typical cellular labeling of Feridex(®) via random endocytosis, chemical conjugation of heparin-SPIO was stable and improved the hypointensity of transplanted islets due to surface modification of every islet. These heparin-SPIO-conjugated islets showed normal viability and insulin secretion, and were quantified by spin echo T(2)-weighted MR imaging with linear correlation depending on transplanted islet mass in vitro and in vivo for 30 days. Also, from the immunohistochemistry, we confirmed the existence of heparin-SPIO and insulin biosynthesis in transplanted islets. However, Feridex-uptake islets showed late glucose responsiveness according to changing glucose concentration although they could normally control the blood glucose levels in diabetic mouse. Thus, we anticipate that this surface labeling with heparin-SPIO can be directly applicable for MR imaging of transplanted islets.

  12. Superhydrophobic surface fabricated on iron substrate by black chromium electrodeposition and its corrosion resistance property

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bo [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Feng, Haitao [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Lin, Feng [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Yabin [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Wang, Liping [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Dong, Yaping [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China); Li, Wu, E-mail: liwu2016@126.com [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai (China); Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resource, Chinese Academy of Science, Xining 810008, Qinghai (China)

    2016-08-15

    Highlights: • Superhydrophobic surface was fabricated by black chromium electrodeposition and stearic acid modification. • The reaction process is simple, and of low cost, and no special instrument or environment is needed. • The obtained superhydrophobic surface presents good water repellency, and performs well at corrosion resistance. - Abstract: The fabrication of superhydrophobic surface on iron substrate is carried out through 20 min black chromium electrodeposition, followed by immersing in 0.05 M ethanolic stearic acid solution for 12 h. The resultant superhydrophobic complex film is characterized by scanning electron microscope (SEM), disperse Spectrometer (EDS), atomic force microscope (AFM), water contact angle (CA), sliding angle (SA) and X-ray photoelectron spectroscope (XPS), and its corrosion resistance property is measured with cyclic voltammetry (CV), linear polarization and electrochemical impedance spectroscopy (EIS). The results show that the fabricated superhydrophobic film has excellent water repellency (CA, 158.8°; SA, 2.1°) and significantly high corrosion resistance (1.31 × 10{sup 6} Ω cm{sup −2}) and excellent corrosion protection efficiency (99.94%).

  13. Evolution of novel bioresorbable iron-manganese implant surfaces and their degradation behaviors in vitro.

    Science.gov (United States)

    Heiden, Michael; Walker, Emily; Nauman, Eric; Stanciu, Lia

    2015-01-01

    The purpose of this study is to advance understanding of surface degradation kinetics for Fe-Mn bioresorbable alloys (specifically Fe-20%Mn) and target degradable fracture fixation implants for hard tissues. This study addresses how arc melted Fe-20%Mn discs degrade in a static, osteogenic medium for up to a 3 month time span. Degradation behavior of these bulk alloys was investigated using both mass loss tests for measuring long-term corrosion rates and potentiostatic tests for following the instantaneous rate of degradation. It was discovered that cold-rolling Fe-20%Mn to 77% cold work (CW) suppressed the instantaneous corrosion rate compared with the cast structure. It was also found that an unstable iron-rich oxide layer forms on the entire surface of these bulk samples and the act of machining the bulk metal into a defined shape may affect the morphology of the oxide layer on the outer edge of the samples during degradation. The mechanisms behind the surface evolution of these potential orthopedic implants are investigated in detail.

  14. Photoemission study of metallic iron nanoparticles surface aging in biological fluids. Influence on biomolecules adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Canivet, L.; Denayer, F.O. [Université de Lille 2, Droit et Santé, 42 rue P. Duez, 59000 Lille (France); Champion, Y.; Cenedese, P. [CNRS-ICMPE, 2 rue H. Dunant, 94320 Thiais (France); Dubot, P., E-mail: pdubot@icmpe.cnrs.fr [CNRS-ICMPE, 2 rue H. Dunant, 94320 Thiais (France)

    2014-07-01

    Iron nanoparticles (nFe) prepared by vaporization and cryogenic condensation process (10–100 nm) has been exposed to Hank's balanced salt solution (HBSS) and the B-Ali cell growth fluids. These media can be used for cellular growth to study nFe penetration through cell membrane and its induced cytotoxicity. Surface chemistry of nFe exposed to such complex fluids has been characterized as the nanoparticles surface can be strongly changed by adsorption or corrosion processes before reaching intracellular medium. Particle size and surface chemistry have been characterized by scanning electron microscopy (SEM) and high-resolution X-ray photoelectron spectroscopy (HR-XPS). Exposition of nFe particles to growth and differentiation media leads to the formation of an oxy-hydroxide layer containing chlorinated species. We found that the passivated Fe{sub 2}O{sub 3} layer of the bare nFe particles is rapidly transformed into a thicker oxy-hydroxide layer that has a greater ability to adsorb molecular ions or ionic biomolecules like proteins or DNA.

  15. External pressure in the hardening of phosphate in tribofilm on iron surfaces

    Directory of Open Access Journals (Sweden)

    Z. Pawlak

    2009-03-01

    Full Text Available Purpose: In the present work we consider our (in progress spectroscopy study of zinc and iron phosphates under the influence external high pressure to determine zinc ion change coordination from tetrahedral to octahedral (or hexahedral structure.Design/methodology/approach: The standard equipment is the optical high pressure cell with diamond (DAC. The DAC is assembled and then vibrational or electronic spectra are collected by mounting the cell in an infrared, Raman, EXAFS or UV-visible spectrometer.Findings: Mechanism by which zinc and iron methaphosphate material is transformed to glassy meta-phosphate is enhancing mechanical properties of tribofilm. The two decades of intensive study demonstrates that Zn (II and Fe (III ions participate to cross-link network under friction, hardening the phosphate.Research limitations/implications: Transition metal atoms with d orbital have flexible coordination numbers, for example zinc acts as a cross-linking agent increasing hardness, by changing coordination from tetrahedral to octahedral. Perhaps the external pressure effect on the [Zn–(O-P-4 ] complex causes a transformation to an [Zn –(O-P-6] grouping.Originality/value: This paper analyses high-pressure spectroscopy which has been applied for the investigation of 3D transition metal ions in solids. When studying pressure effects on coordination compounds structure, we can expect changes in ground electronic state (spin-crossovers, electronic spectra due to structural distortions (piezochromism, and changes in the ligand field causing shifts in the electronic transitions.

  16. Spectrophotometric Simultaneous Determination of Zinc(Ⅱ),Manganese(Ⅱ) and Iron(Ⅱ) in Pharmaceutical Preparations Using OSC-PLS

    Institute of Scientific and Technical Information of China (English)

    Ali NIAZI; Azadeh YAZDANIPOUR; Mohammad GOODARZI; Hamidreza KAMKAR; Ali RAFINEJAD

    2006-01-01

    This work reports the spectrophotometric simultaneous determination of zinc(Ⅱ),manganese(Ⅱ) and iron(Ⅱ) in pharmaceutical preparation, using orthogonal signal correctionpartial least squares (OSC-PLS). All the factors affecting on the sensitivity were optimized and the linear dynamic range for determination of these metals was found. The PLS modeling was used for the multivariate calibration of the spectrophotometric data. The OSC was used for preprocessing of data matrices and the prediction results of model. The experimental calibration matrix was designed by measuring the absorbance over the range 450-570 nm for 21 samples of The RMSEP for zinc(Ⅱ), manganese(Ⅱ) and iron(Ⅱ) using OSC-PLS were 0.0164, 0.0132, 0.0146,respectively. The proposed method was successfully applied the determination of zinc(Ⅱ),manganese(Ⅱ) and iron(Ⅱ) in pharmaceutical preparations.

  17. Sustaining reactivity of Fe(0) for nitrate reduction via electron transfer between dissolved Fe(2+) and surface iron oxides.

    Science.gov (United States)

    Han, Luchao; yang, Li; Wang, Haibo; Hu, Xuexiang; Chen, Zhan; Hu, Chun

    2016-05-05

    The mechanism of the effects of Fe(2+)(aq) on the reduction of NO3(-) by Fe(0) was investigated. The effects of initial pH on the rate of NO3(-) reduction and the Fe(0) surface characteristics revealed Fe(2+)(aq) and the characteristics of minerals on the surface of Fe(0) played an important role in NO3(-) reduction. Both NO3(-) reduction and the decrease of Fe(2+)(aq) exhibited similar kinetics and were promoted by each other. This promotion was associated with the types of the surface iron oxides of Fe(0). Additionally, further reduction of NO3(-) produced more surface iron oxides, supplying more active sites for Fe(2+)(aq), resulting in more electron transfer between Fe(2+) and surface iron oxides and a higher reaction rate. Using the isotope specificity of (57)Fe Mossbauer spectroscopy, it was verified that the Fe(2+)(aq) was continuously converted into Fe(3+) oxides on the surface of Fe(0) and then converted into Fe3O4 via electron transfer between Fe(2+) and the pre-existing surface Fe(3+) oxides. Electrochemistry measurements confirmed that the spontaneous electron transfer between the Fe(2+) and structural Fe(3+) species accelerated the interfacial electron transfer between the Fe species and NO3(-). This study provides a new insight into the interaction between Fe species and contaminants and interface electron transfer. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Simple method for coating Si (1 0 0) surfaces with ferritin monolayers-Iron oxide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulos, Georgios, E-mail: geopap@bio.uth.gr [University of Thessaly, Department of Biochemistry and Biotechnology, Ploutonos 26 and Aeolou, 41221 Larisa (Greece); Anetakis, Constantine, E-mail: kanetaki@physics.auth.gr [Aristotle University of Thessaloniki, Department of Physics, Laboratory for Thin Films - Nanosystems and Nanometrology and Laboratory of Electronic Microscopy, 54124 Thessaloniki (Greece); Gravalidis, Christoforos, E-mail: cgrava@physics.auth.gr [Aristotle University of Thessaloniki, Department of Physics, Laboratory for Thin Films - Nanosystems and Nanometrology and Laboratory of Electronic Microscopy, 54124 Thessaloniki (Greece); Kassavetis, Spiros, E-mail: skasa@physics.auth.gr [Aristotle University of Thessaloniki, Department of Physics, Laboratory for Thin Films - Nanosystems and Nanometrology and Laboratory of Electronic Microscopy, 54124 Thessaloniki (Greece); Vouroutzis, Nikolaos, E-mail: nikosv@auth.gr [Aristotle University of Thessaloniki, Department of Physics, Laboratory for Thin Films - Nanosystems and Nanometrology and Laboratory of Electronic Microscopy, 54124 Thessaloniki (Greece); Frangis, Nikolaos, E-mail: frangis@auth.gr [Aristotle University of Thessaloniki, Department of Physics, Laboratory for Thin Films - Nanosystems and Nanometrology and Laboratory of Electronic Microscopy, 54124 Thessaloniki (Greece); Logothetidis, Stergios, E-mail: logot@auth.gr [Aristotle University of Thessaloniki, Department of Physics, Laboratory for Thin Films - Nanosystems and Nanometrology and Laboratory of Electronic Microscopy, 54124 Thessaloniki (Greece)

    2011-04-15

    With the goal to develop iron oxide quantum dots we developed a simple method to spread horse spleen ferritin monolayers on a Si (1 0 0) surface. Application of atomic force microscopy and spectroscopic ellipsometry showed the existence of regions with dense ferritin monolayers. Application of transmission electron microscopy identified the core of the spread ferritin as FeO nanocrystals.

  19. Determinants of biofilm formation and cleanability of titanium surfaces.

    Science.gov (United States)

    Zaugg, Lucia K; Astasov-Frauenhoffer, Monika; Braissant, Olivier; Hauser-Gerspach, Irmgard; Waltimo, Tuomas; Zitzmann, Nicola U

    2017-04-01

    The aim of the present study was to analyze biofilm formation on four different titanium-based surfaces (machined titanium zirconium (TiZr) alloy, M; machined, acid-etched TiZr alloy, modMA; machined, sandblasted, acid-etched TiZr alloy, modSLA; and micro-grooved titanium aluminum vanadium alloy, TAV MG) in an experimental human model. Custom-made discs were mounted in individual intraoral splint housings and worn by 16 volunteers for 24 h. The safranin staining assay, isothermal microcalorimetry (IMC), and SEM were applied before and after surface cleaning. The hydrophilic surfaces modMA and modSLA with greater surface micro-roughness exhibited significantly more biofilm than the hydrophobic surfaces TAV MG and M. The standardized cleaning procedure substantially reduced the biofilm mass on all surfaces. After cleaning, the IMC analyses demonstrated a longer lag time of the growth curve on TAV MG compared to modSLA. Inter- and intraindividual variations in biofilm formation on the titanium discs were evident throughout the study. Surface hydrophilicity and roughness enhanced biofilm formation in vivo, whereas surface topography was the most influential factor that determined surface cleanability. While the grooved surface retained larger amounts of initial biofilm, the machined surface was easier to clean, but proliferation indicated by increased metabolic activity (growth rate) in IMC occurred despite mechanical biofilm removal. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Determination of Thermal Activation Energy and Grain Size of Iron Hexadecachloro Phthalocyanine Thin Films

    Directory of Open Access Journals (Sweden)

    Raji Koshy

    2011-01-01

    Full Text Available Electrical, structural and surface morphological properties of Iron hexadecachloro phthalocyanine thin films deposited onto glass substrates are studied as a function of post deposition annealing temperature in air. Organic semiconductors are extensively used in optical and electronic devices such as organic photovoltaic solar cells (OSC, thin film transistors (OTFT and organic light emitting diodes (OLED. Metal phthalocyanines are one of the most promising candidates to be used in the fabrication of such devices. A No. of phthalocyanines have been extensively studied. But not much work have been carried out in Cl16FePc thin films. Basic characteristics of Cl16FePc are not reported in literature. Hexadecacholoro phthalocyanines have attracted interest as possible n-type organic semiconductor with high electron mobility and good stability characteristics. In the present work we investigate the activation energy of the Cl16FePc thin films as a function of air annealing temperature. We also report the film structure and surface morphology by X-ray diffraction (XRD and Scanning electron microscopy (SEM.

  1. Development of analytical methods for the determination of sub-ppm concentrations of palladium and iron in methotrexate.

    Science.gov (United States)

    Niemelä, Matti; Kola, Harri; Eilola, Keijo; Perämäki, Paavo

    2004-05-28

    Analytical methods for limit test (1 microgg(-1)) determination of iron and palladium in the drug substance methotrexate (MTX) were developed. The methods developed were based on microwave-assisted, vapor-phase digestion using quartz inserts inside the digestion vessels, followed by instrumental determination. Iron was determined by graphite furnace atomic absorption spectrometry (GFAAS) and palladium by direct current plasma optical emission spectrometry (DCP-OES). Detection limits of 0.20 microgg(-1) for iron by GFAAS and 0.30 microgg(-1) for palladium by DCP-OES in MTX were obtained. The validity of the methods was studied by spike recovery tests and by analyzing certified reference material (NIST 8433 corn bran, Fe determination) and an organometallic compound ([(C(6)H(5))(3)P](2)PdCl(2), Pd determination). In addition, the specificity of the GFAAS technique for iron determination was confirmed by comparing the results obtained by GFAAS with those obtained by hexapole collision cell, inductively coupled plasma mass spectrometry (ICP-MS).

  2. Grafting of diazonium salts on oxides surface: formation of aryl-O bonds on iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Brymora, Katarzyna [LUNAM Université du Maine, IMMM UMR CNRS 6283 (France); Fouineau, Jonathan; Eddarir, Asma; Chau, François [Université Paris Diderot, Sorbonne Paris Cité, ITODYS CNRS UMR 7086 (France); Yaacoub, Nader; Grenèche, Jean-Marc [LUNAM Université du Maine, IMMM UMR CNRS 6283 (France); Pinson, Jean; Ammar, Souad [Université Paris Diderot, Sorbonne Paris Cité, ITODYS CNRS UMR 7086 (France); Calvayrac, Florent, E-mail: florent.calvayrac@univ-lemans.fr [LUNAM Université du Maine, IMMM UMR CNRS 6283 (France)

    2015-11-15

    Combining ab initio modeling and {sup 57}Fe Mössbauer spectrometry, we characterized the nature of the chemical linkage of aminoalkyl arenediazonium salt on the surface of iron oxide nanoparticles. We established that it is built through a metal–oxygen–carbon bonding and not a metal–carbon one, as usually suggested and commonly observed in previously studied metal- or carbon-based surfaces.

  3. Use of near infrared correlation spectroscopy for quantitation of surface iron, absorbed water and stored electronic energy in a suite of Mars soil analog materials

    Science.gov (United States)

    Coyne, Lelia M.; Banin, Amos; Carle, Glenn; Orenberg, James; Scattergood, Thomas

    1989-01-01

    A number of questions concerning the surface mineralogy and the history of water on Mars remain unresolved using the Viking analyses and Earth-based telescopic data. Identification and quantitation of iron-bearing clays on Mars would elucidate these outstanding issues. Near infrared correlation analysis, a method typically applied to qualitative and quantitative analysis of individual constituents of multicomponent mixtures, is adapted here to selection of distinctive features of a small, highly homologous series of Fe/Ca-exchanged montmorillonites and several kalinites. Independently determined measures of surface iron, relative humidity and stored electronic energy were used as constituent data for linear regression of the constituent vs. reflectance data throughout the spectral region 0.68 to 2.5 micrometers. High correlations were found in appropriate regions for all three constituents, though that with stored energy is still considered tenuous. Quantitation was improved using 1st and 2nd derivative spectra. High resolution data over a broad spectral range would be required to quantitatively identify iron-bearing clays by remotely sensed reflectance.

  4. Temperature-driven oxidation behavior on pure iron surface investigated by time-resolved EXAFS measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doh, S.J.; Lee, J.M.; Je, J.H. [POSTECH, Pohang (Korea, Republic of); Noh, D.Y. [K-JIST, Kwangju (Korea, Republic of). Dept. of Materials Science and Engineering

    1998-12-31

    The surface-front oxidation mechanism of iron was investigated by time-resolved, glancing-angle Fe K-edge fluorescence EXAFS measurements at various oxidation temperatures of 200--700 C. The glancing angle was chosen according to the depth of the oxide layer, roughly 1,500--2,000 {angstrom}. The oxidation behavior under rapid heating (up to 600 C within 10 minutes) was compared with the slowly heated oxidation process using the Quick-EXAFS measurements. In the slowly heated process, Fe{sub 3}O{sub 4} was the dominating phase at a relatively low temperature (300--400 C) initially. However, at a relatively high temperature (above 600 C), the Fe{sub 2}O{sub 3} and FeO crystalline phases are gradually enriched as the successive oxidation process involving intrusive oxygen proceeded. Remarkably under a prolonged heat treatment above 600 C, the stable FeO phase that exists in a deep-lying interface structure and Fe{sub 2}O{sub 3} phase eventually dominates the thick front-surface structure. In a quickly heated process, however, Fe{sub 3}O{sub 4} phase is less dominating, which is contradictory to the commonly accepted oxidation models. The EXAFS results are discussed in conjunction with the x-ray diffraction features under the same heat treatment conditions.

  5. Effect of magnetic iron oxide nanoparticles in surface water treatment: trace minerals and microbes.

    Science.gov (United States)

    Lakshmanan, Ramnath; Okoli, Chuka; Boutonnet, Magali; Järås, Sven; Rajarao, Gunaratna K

    2013-02-01

    The existing water treatment process often uses chemicals, which is of high health and environmental concern. The present study focused on the efficiency of microemulsion prepared magnetic iron oxide nanoparticles (ME-MIONs) and protein-functionalized nanoparticles (MOCP+ME-MIONs) in water treatment. Their influence on mineral ions and microorganisms present in the surface water from lake Brunnsviken and Örlången, Sweden were investigated. Ion analysis of water samples before and after treatment with nanoparticles was performed. Microbial content was analyzed by colony forming units (CFU/ml). The results impart that ME-MIONs could reduce the water turbidity even in low turbid water samples. Reduction of microbial content (98%) was observed at 37°C and more than 90% reduction was seen at RT and 30 °C when compared to untreated samples from lake Örlången. The investigated surface water treatment method with ME-MIONs was not significantly affecting the mineral ion composition, which implies their potential complement in the existing treatment process.

  6. Effect of surface functionalisation on the interaction of iron oxide nanoparticles with polymerase chain reaction.

    Science.gov (United States)

    Aysan, Ayse Beyza; Knejzlík, Zdeněk; Ulbrich, Pavel; Šoltys, Marek; Zadražil, Aleš; Štěpánek, František

    2017-05-01

    The combination of nanoparticles with the polymerase chain reaction (PCR) can have benefits such as easier sample handling or higher sensitivity, but also drawbacks such as loss of colloidal stability or inhibition of the PCR. The present work systematically investigates the interaction of magnetic iron oxide nanoparticles (MIONs) with the PCR in terms of colloidal stability and potential PCR inhibition due to interaction between the PCR components and the nanoparticle surface. Several types of MIONs with and without surface functionalisation by sodium citrate, dextran and 3-aminopropyl-triethoxysilane (APTES) were prepared and characterised by Transmission Electron Microscopy (TEM), dynamic light scattering (DLS) and Fourier Transform Infrared (FT-IR) spectroscopy. Colloidal stability in the presence of the PCR components was investigated both at room temperature and under PCR thermo-cycling. Dextran-stabilized MIONs show the best colloidal stability in the PCR mix at both room and elevated temperatures. Citrate- and APTES-stabilised as well as uncoated MIONs show a comparable PCR inhibition near the concentration 0.1mgml(-1) while the inhibition of dextran stabilized MIONs became apparent near 0.5mgml(-1). It was demonstrated that the PCR could be effectively carried out even in the presence of elevated concentration of MIONs up to 2mgml(-1) by choosing the right coating approach and supplementing the reaction mix by critical components, Taq DNA polymerase and Mg(2+) ions. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Control of the interparticle spacing in superparamagnetic iron oxide nanoparticle clusters by surface ligand engineering

    Science.gov (United States)

    Dan, Wang; Bingbing, Lin; Taipeng, Shen; Jun, Wu; Fuhua, Hao; Chunchao, Xia; Qiyong, Gong; Huiru, Tang; Bin, Song; Hua, Ai

    2016-07-01

    Polymer-mediated self-assembly of superparamagnetic iron oxide (SPIO) nanoparticles allows modulation of the structure of SPIO nanocrystal cluster and their magnetic properties. In this study, dopamine-functionalized polyesters (DA-polyester) were used to directly control the magnetic nanoparticle spacing and its effect on magnetic resonance relaxation properties of these clusters was investigated. Monodisperse SPIO nanocrystals with different surface coating materials (poly(ɛ-caprolactone), poly(lactic acid)) of different molecular weights containing dopamine (DA) structure (DA-PCL2k, DA-PCL1k, DA-PLA1k)) were prepared via ligand exchange reaction, and these nanocrystals were encapsulated inside amphiphilic polymer micelles to modulate the SPIO nanocrystal interparticle spacing. Small-angle x-ray scattering (SAXS) was applied to quantify the interparticle spacing of SPIO clusters. The results demonstrated that the tailored magnetic nanoparticle clusters featured controllable interparticle spacing providing directly by the different surface coating of SPIO nanocrystals. Systematic modulation of SPIO nanocrystal interparticle spacing can regulate the saturation magnetization (M s) and T 2 relaxation of the aggregation, and lead to increased magnetic resonance (MR) relaxation properties with decreased interparticle spacing. Project supported by the National Key Basic Research Program of China (Grant No. 2013CB933903), the National Key Technology R&D Program of China (Grant No. 2012BAI23B08), and the National Natural Science Foundation of China (Grant Nos. 20974065, 51173117, and 50830107).

  8. Control of the interparticle spacing in superparamagnetic iron oxide nanoparticle clusters by surface ligand engineering

    Institute of Scientific and Technical Information of China (English)

    王丹; 艾华; 林兵兵; 申太鹏; 吴君; 豪富华; 夏春潮; 龚启勇; 唐惠儒; 宋彬

    2016-01-01

    Polymer-mediated self-assembly of superparamagnetic iron oxide (SPIO) nanoparticles allows modulation of the structure of SPIO nanocrystal cluster and their magnetic properties. In this study, dopamine-functionalized polyesters (DA-polyester) were used to directly control the magnetic nanoparticle spacing and its effect on magnetic resonance relaxation properties of these clusters was investigated. Monodisperse SPIO nanocrystals with different surface coating materials (poly(ε-caprolactone), poly(lactic acid)) of different molecular weights containing dopamine (DA) structure (DA-PCL2k, DA-PCL1k, DA-PLA1k)) were prepared via ligand exchange reaction, and these nanocrystals were encapsulated inside am-phiphilic polymer micelles to modulate the SPIO nanocrystal interparticle spacing. Small-angle x-ray scattering (SAXS) was applied to quantify the interparticle spacing of SPIO clusters. The results demonstrated that the tailored magnetic nanoparticle clusters featured controllable interparticle spacing providing directly by the different surface coating of SPIO nanocrystals. Systematic modulation of SPIO nanocrystal interparticle spacing can regulate the saturation magnetization (Ms) and T2 relaxation of the aggregation, and lead to increased magnetic resonance (MR) relaxation properties with de-creased interparticle spacing.

  9. A cheap gas-liquid-solid method for nanodeposition of iron on the surface of flaky graphite powder.

    Science.gov (United States)

    Chen, Yuan; Meng, Xianwei; Tang, Fangqiong; Ren, Jun

    2008-06-03

    A cheap gas-liquid-solid method to prepare a nanodeposition of iron on the surface of a micrometer-size flaky graphite powder is described. This method is suited not only for spherical, but also nonspherical small substrates. The method is only a one-step process, in which decomposition of iron pentacarbonyl is induced by nitrogen gas in a 90 degrees C reactor. This synthetic route simplifies the operation procedure and manufacturing equipment, and decreases the reaction temperature, compared with conventional liquid-solid-phase methods and gas-solid-phase methods.

  10. Determination of iron in highly-saline matrices by FIA-ICP-MS

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    Analysis of iron by inductively-coupled-plasma mass-spectrometry (ICP-MS) may be significantly improved by applying a protocol of flow-injection analysis. The iron species of the sample was preconcentrated by an ammonia buffer at pH = 9.2 on a filterless nylon-knotted reactor, and the adsorbed...... species were subsequently eluted by hydrochloric acid and analysed by ICP-MS. During the FIA step of preconcentration, a high degree of salinity did not influence the adsorption mechanism of iron, which may be related to formation of iron-hydroxide complexes at the sites of amide moieties of the nylon...

  11. Iron prophylaxis during pregnancy -- how much iron is needed? A randomized dose- response study of 20-80 mg ferrous iron daily in pregnant women

    DEFF Research Database (Denmark)

    Milman, Nils; Bergholt, Thomas; Eriksen, Lisbeth

    2005-01-01

    To determine the lowest dose of iron preventative of iron deficiency and iron deficiency anemia in pregnancy.......To determine the lowest dose of iron preventative of iron deficiency and iron deficiency anemia in pregnancy....

  12. SURFACE CHARACTER OF IRON OXIDE/CARBON NANOPARTICLES SYNTHESIZED BY SUBMERGED ARC DISCHARGE METHOD IN ETHANOL/UREA MEDIUM

    Directory of Open Access Journals (Sweden)

    Teguh Endah Saraswati

    2017-08-01

    Full Text Available Synthesis of iron oxide nanoparticles modified with carbon has been successfully performed by submerged arc-discharge method in ethanol/urea medium. Iron oxide used in the fabrication process was prepared by iron electrolysis in an electrolyte solution of NaCl. Fabrication of nanoparticles in this method uses two graphite electrodes. One of them was made in a pointed shape and the other graphite electrodes hollowed out and filled with a mixture of iron oxide, graphite and glue silica (as binder with a ratio of 1:3:1 (w/w/w. The liquid medium used in this method is a mixture solution of ethanol 50% and urea (0%, 10%, 25% and 50% with a volume ratio of 1:1 (v/v. The crystalline of iron oxide was characterized using X-Ray Diffraction (XRD, compared to JCPDS No. 89-0597, No. 89-0691 and No. 39-1346. Variations in the urea concentration in the liquid medium provided the changes of the surface character of the synthesized nanoparticles. The changes of surface character were analyzed by the Fourier Transform Infra Red (FTIR spectra and nanoparticle dispersion in water and ethanol. FTIR spectra showed the absorption of Fe-O, CH, CN, C = O, OH and NH at 460-555 cm-1, 650-1000 cm-1, 1000-1350 cm-1, 1640-1680 cm-1, 2400-3400 cm-1, 3200-3400 cm-1, 3100-3500 cm-1, respectively. The best hydrophilic surface character achieved when the nanoparticle was synthesized in medium of ethanol 50% with the addition of urea50%. The existence of a functional group attached on the surface of nanoparticles synthesized in ethanol/urea makes these nanoparticles had better dispersion than nanoparticles synthesized in ethanol medium without urea addition.

  13. The nucleation, growth and thermal stability of iron clusters on a TiO2(110) surface

    Science.gov (United States)

    Madej, Ewa; Spiridis, Nika; Socha, Robert Piotr; Wolanin, Barbara; Korecki, Józef

    2017-09-01

    The nucleation and initial growth of Fe on the (1 × 1) rutile TiO2(110) substrate as a function of coverage and annealing temperature were studied using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The deposition of 0.03 ML-0.3 ML (monolayer) of Fe resulted in the growth of one-, two- and three-dimensional iron clusters. Surface annealing at 373 K and 473 K resulted in a moderate sintering of the Fe clusters, whereas annealing at higher temperatures led to Fe incorporation into the substrate. The analysis of the Fe 2p core excitations showed that even after room temperature processes, iron was partially oxidized at the iron/titania interface.

  14. Determination of Surface Exciton Energies by Velocity Resolved Atomic Desorption

    Energy Technology Data Exchange (ETDEWEB)

    Hess, Wayne P.; Joly, Alan G.; Beck, Kenneth M.; Sushko, Petr V.; Shluger, Alexander L.

    2004-08-20

    We have developed a new method for determining surface exciton band energies in alkali halides based on velocity-resolved atomic desorption (VRAD). Using this new method, we predict the surface exciton energies for K1, KBr, KC1, and NaC1 within +0.15 eV. Our data, combined with the available EELS data for alkali fluorides, demonstrate a universal linear correlation with the inverse inter-atomic distance in these materials. The results suggest that surface excitons exist in all alkali halides and their excitation energies can be predicted from the known bulk exciton energies and the obtained correlation plot.

  15. A biological switch at the ocean surface as a cause of laminations in a Precambrian iron formation

    Science.gov (United States)

    Hashizume, K.; Pinti, D. L.; Orberger, B.; Cloquet, C.; Jayananda, M.; Soyama, H.

    2016-07-01

    Banded iron formations (BIFs) exhibit alternating silica- and iron-rich laminae, potentially reflecting the dynamics of the paleo-environments in which they were formed, although the exact mechanism remains unclear. Here the formation of a 2.7-2.9 Ga BIF from Dharwar Craton, India, is deciphered by analyzing the inter-band variations of the redox-sensitive isotope biomarkers, 15N/14N and 56Fe/54Fe. Organic matter with δ15N values as high as + 12.0 ± 0.8 ‰ appears to be trapped in silica. Iron oxides exhibit systematically positive δ56Fe values, ranging between + 0.80 ± 0.05 ‰ and + 1.67 ± 0.02 ‰. Compared to the iron-rich bands, silica-rich bands, which show higher δ56Fe values, exhibit an order of magnitude higher concentrations of 15N-rich organic nitrogen, normalized by the abundances of its host silica. The presence of 15N-rich organic matter may imply the emergence of a modern-like biological nitrogen cycle that requires the formation of oxidized nitrogen compounds. The higher concentration of 15N-rich organic nitrogen for the silica-rich bands possibly suggests that the photosynthetic activity was higher during the formation periods of these bands. The heavier iron isotope compositions of the silica-rich bands cannot be explained alone by iron oxidation through probable pathways. The relative 56Fe-enrichment in silica-rich bands is explained here by the progressive dissolution of iron oxides to the ocean, through iron reduction by 15N-rich organic matter actively produced at the ocean surface. The formation of iron-rich bands possibly corresponds to periods of reduced biological productivity, when precipitated iron was not effectively dissolved to the ocean. The observed shift in the organic concentration between Fe- and Si-rich bands could be the switch that triggered the BIF laminations. This shift could conceivably represent periodic fluctuations in the oxygen generation, which possibly occurred over periods of millennia, at the dawn of the

  16. Effect of laser surface hardening on the microstructure, hardness and residual stresses of austempered ductile iron grades

    Energy Technology Data Exchange (ETDEWEB)

    Soriano, C., E-mail: csoriano@tekniker.es [Tekniker-IK4, Manufacturing Processes Department, Avda. Otaola 20, CP-20600, Eibar (Gipuzkoa) (Spain); Leunda, J.; Lambarri, J.; Garcia Navas, V.; Sanz, C. [Tekniker-IK4, Manufacturing Processes Department, Avda. Otaola 20, CP-20600, Eibar (Gipuzkoa) (Spain)

    2011-06-01

    A study of the laser surface hardening process of two austempered ductile iron grades, with different austempering treatments has been carried out. Hardening was performed with an infrared continuous wave Nd:YAG laser in cylindrical specimens. The microstructure of the laser hardened samples was investigated using an optical microscope, microhardness profiles were measured and surface and radial residual stresses were studied by an X-ray diffractometer. Similar results were achieved for both materials. A coarse martensite with retained austenite structure was found in the treated area, resulting in a wear resistant effective layer of 0.6 mm to 1 mm with a microhardness between 650 HV and 800 HV. Compressive residual stresses have been found at the hardened area being in agreement with the microhardness and microstructural variations observed. The achieved results point out that the laser surface hardening is a suitable method for improving the mechanical properties of austempered ductile irons.

  17. Determination of iron sulphides in roofing slates from the north west of Spain

    Directory of Open Access Journals (Sweden)

    García-Guinea, J.

    2002-06-01

    Full Text Available The most important production of roofing slates in the world is quarried from the Ordovician formations of the Truchas Syncline, which have the largest amount of working quarries. Roofing slates, sometimes, have crystallized iron sulphides such as pyrite, pyrrhotite and other minerals. These iron sulphides oxidise and stain the tiles when are exposed to atmospheric conditions, so much oxidized how much more inclined is the roof. Galician quarrymen distinguish between harmless pyrite (i.e., resistant cubes of pyrite and damaging pyrite (i.e., other alterable metallic minerals such as pyrrhotite, chalcopyrite, marcasite and arsenopyirite. An improved identification method is proposed using both methods (a chemical element ratios of samples under electron microprobes and (b quantitative determination of the iron sulphides in the slate measuring the oxidized areas by digital camera. The analysed Fe/S ratios, in an XY plot, of seventy metallic samples, define three separated zones: pyrite, pyrrhotite and iron oxi-hydroxides. Quantitative determination of iron sulphides in the slate tile were performed by sinking the tile horizontally for six hours in oxygen peroxide (3% diluted and capturing the oxidation areas with a magnetic camera and analysing the bitmap images with Sigma-Scan 5 software. The proposed method is faster than the Spanish UNE norm (UNE-EN- 12326-2 Sept.2000, which requires thermal strike cycles for a month. The necessary use of heavy analytical equipment such as electron microprobes can be facilitated by installing it in the Slate Technological Centre of Sobradelo de Valdeorras (Orense or by using a simple optical stereoscopic zoom microscope to classify the iron minerals.

    Las formaciones ordovícicas del Sinclinal de Duchas concentran la mayor producción mundial de pizarra para cubiertas y el mayor número de canteras en producción. Las pizarras para cubiertas muchas veces contienen sulfuros de hierro cristalizados en forma

  18. Determination of iron in drinking water after its flotation concentration by two new dithiocarbamate collectors.

    Science.gov (United States)

    Pavlovska, Gorica; Stafilov, Trajče; Čundeva, Katarina

    2015-01-01

    Two new methods for the determination of iron by atomic absorption spectrometry (AAS) are proposed for drinking water. The determination was made after flotation concentration of Fe by using of two new flotation collectors: lead(II) heptyldithiocarbamate, Pb(HpDTC)2 and cobalt(III) heptyldithiocarbamate Co(HpDTC)3. All important parameters for the two proposed procedures were optimised (pH, mass of Pb, mass of Co, amount of HpDTC(-), type of surfactant, induction time, etc.). Flotation recovery (R) of Fe was very high (from 94.4 to 104.4%) for the two proposed procedures. The detection limit of the methods was 2.17 μg L(-1) for Pb(HpDTC)2 and 2.39 μg L(-1) for Co(HpDTC)3, respectively. The proposed methods have been applied for the analysis of five samples of drinking water. The acquired AAS results for Fe by both new methods were compared with those obtained by inductively coupled plasma-atomic emission spectrometry (AES-ICP). It is shown that they are in good agreement. The results are also confirmed by the method of standard additions.

  19. High-precision determination of the isotopic composition of dissolved iron in iron depleted seawater by double spike multicollector-ICPMS.

    Science.gov (United States)

    Lacan, Francois; Radic, Amandine; Labatut, Marie; Jeandel, Catherine; Poitrasson, Franck; Sarthou, Geraldine; Pradoux, Catherine; Chmeleff, Jerome; Freydier, Remi

    2010-09-01

    This work demonstrates the feasibility of the measurement of the isotopic composition of dissolved iron in seawater for an iron concentration range, 0.05-1 nmol L(-1), allowing measurements in most oceanic waters, including Fe depleted waters of high nutrient low chlorophyll areas. It presents a detailed description of our previously published protocol, with significant improvements on detection limit and blank contribution. Iron is preconcentrated using a nitriloacetic acid superflow resin and purified using an AG 1-x4 anion exchange resin. The isotopic ratios are measured with a multicollector-inductively coupled plasma mass spectrometer (MC-ICPMS) Neptune, coupled with a desolvator (Aridus II or Apex-Q), using a (57)Fe-(58)Fe double spike mass bias correction. A Monte Carlo test shows that optimum precision is obtained for a double spike composed of approximately 50% (57)Fe and 50% (58)Fe and a sample to double spike quantity ratio of approximately 1. Total procedural yield is 91 +/- 25% (2SD, n = 55) for sample sizes from 20 to 2 L. The procedural blank ranges from 1.4 to 1.1 ng, for sample sizes ranging from 20 to 2 L, respectively, which, converted into Fe concentrations, corresponds to blank contributions of 0.001 and 0.010 nmol L(-1), respectively. Measurement precision determined from replicate measurements of seawater samples and standard solutions is 0.08 per thousand (delta(56)Fe, 2SD). The precision is sufficient to clearly detect and quantify isotopic variations in the oceans, which so far have been observed to span 2.5 per thousand and thus opens new perspectives to elucidate the oceanic iron cycle.

  20. Determination of iron in highly-saline matrices by FIA-ICP-MS

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    species were subsequently eluted by hydrochloric acid and analysed by ICP-MS. During the FIA step of preconcentration, a high degree of salinity did not influence the adsorption mechanism of iron, which may be related to formation of iron-hydroxide complexes at the sites of amide moieties of the nylon...

  1. Iron deficiency and malaria as determinants of anaemia in African children

    NARCIS (Netherlands)

    Verhoef, H.

    2001-01-01

    Approximately three quarters of east African children <5 y of age suffer from anaemia, which is due, at least in part, to malaria and iron deficiency. In children in areas of seasonal malaria, the benefits of iron supplementation may not outweigh possible inherent risks of adverse effects caused

  2. Iron deficiency and malaria as determinants of anaemia in African children

    NARCIS (Netherlands)

    Verhoef, H.

    2001-01-01

    Approximately three quarters of east African children <5 y of age suffer from anaemia, which is due, at least in part, to malaria and iron deficiency. In children in areas of seasonal malaria, the benefits of iron supplementation may not outweigh possible inherent risks of adverse ef

  3. Iron deficiency and malaria as determinants of anaemia in African children

    NARCIS (Netherlands)

    Verhoef, H.

    2001-01-01

    Approximately three quarters of east African children <5 y of age suffer from anaemia, which is due, at least in part, to malaria and iron deficiency. In children in areas of seasonal malaria, the benefits of iron supplementation may not outweigh possible inherent risks of adverse

  4. Spectroscopic determination of optimal hydration time of zircon surface

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Garcia R, G. [Instituto Tecnologico de Toluca, Division de Estudios del Posgrado, Av. Tecnologico s/n, Ex-Rancho La Virgen, 52140 Metepec, Estado de Mexico (Mexico); Garcia G, N., E-mail: eduardo.ordonez@inin.gob.m [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Av. Colon y Av. Tollocan, 50180 Toluca, Estado de Mexico (Mexico)

    2010-07-01

    When a mineral surface is immersed in an aqueous solution, it develops and electric charge produced by the amphoteric dissociation of hydroxyl groups created by the hydration of the solid surface. This is one influential surface property. The complete hydration process takes a time which is specific for each mineral species. The knowledge of the aqueous solution contact time for complete surface hydration is mandatory for further surface phenomena studies. This study deals with the optimal hydration time of the raw zircon (ZrSiO{sub 4}) surface comparing the classical potentiometric titrations with a fluorescence spectroscopy technique. The latter is easy and rea liable as it demands only one sample batch to determine the optimal time to ensure a total hydration of the zircon surface. The analytical results of neutron activation analysis showed the presence of trace quantities of Dy{sup 3+}, Eu{sup 3+} and Er{sup 3} in the bulk of zircon. The Dy{sup 3+} is structured in the zircon crystalline lattice and undergoes the same chemical reactions as zircon. Furthermore, the Dy{sup 3+} has a good fluorescent response whose intensity is enhanced by hydration molecules. The results show that, according to the potentiometric analysis, the hydration process for each batch (at least 8 sample batches) takes around 2 h, while the spectrometric method indicates only 5 minutes from only one batch. Both methods showed that the zircon surface have a 16 h optimal hydration time. (Author)

  5. Corrosion inhibition of Eleusine aegyptiaca and Croton rottleri leaf extracts on cast iron surface in 1 M HCl medium

    Energy Technology Data Exchange (ETDEWEB)

    Rajeswari, Velayutham [Department of Chemistry, Periyar University, Salem 636011 (India); Kesavan, Devarayan [Department of Chemistry, Dhirajlal Gandhi College of Technology, Salem 636309 (India); Gopiraman, Mayakrishnan [Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015 (India); Viswanathamurthi, Periasamy, E-mail: viswanathamurthi72@gmail.com [Department of Chemistry, Periyar University, Salem 636011 (India); Poonkuzhali, Kaliyaperumal; Palvannan, Thayumanavan [Department of Bio-Chemistry, Periyar University, Salem 636011 (India)

    2014-09-30

    Graphical abstract: - Highlights: • Eleusine aegyptiaca and Croton rottleri are commonly available, less-toxic and eco-friendly inhibitors for cast iron corrosion. • The active constituents present in extracts adsorbed on the iron surface to inhibit the acidic corrosion. • The higher values of E{sub a} and ΔH{sup *} point out the higher inhibition efficiency noticed for the inhibitors. • Weight loss methods at various temperature and spectral data provides evidence for adsorption mechanism of inhibitors. - Abstract: The adsorption and corrosion inhibition activities of Eleusine aegyptiaca (E. aegyptiaca) and Croton rottleri (C. rottleri) leaf extracts on cast iron corrosion in 1 M hydrochloric acid solution were studied first time by weight loss and electrochemical techniques viz., Tafel polarization and electrochemical impedance spectroscopy. The results obtained from the weight loss and electrochemical methods showed that the inhibition efficiency increased with inhibitor concentrations. It was found that the extracts acted as mixed-type inhibitors. The addition of halide additives (KCl, KBr, and KI) on the inhibition efficiency has also been investigated. The adsorption of the inhibitors on cast iron surface both in the presence and absence of halides follows the Langmuir adsorption isotherm model. The inhibiting nature of the inhibitors was supported by FT-IR, UV–vis, Wide-angle X-ray diffraction and SEM methods.

  6. Influence of different synthesis approach on doping behavior of silver nanoparticles onto the iron oxide-silica coreshell surfaces

    Science.gov (United States)

    Mahmed, Norsuria; Jiang, Hua; Heczko, Oleg; Söderberg, Outi; Hannula, Simo-Pekka

    2012-08-01

    Silver (Ag) nanoparticles with the crystallite size ranging from 13-24 nm were successfully doped onto the surface of iron oxide-silica coreshell particles. In the process, iron oxide particles having a size distribution within 8-19 nm were prepared by using a reverse co-precipitation method followed by the formation of iron oxide-core with silica shell (with 50-150 nm diameter of silica spheres) by using a modified Stöber method. The reduction of Ag ions was done at room temperature in a solution containing polyvinylpyrrolidone and ethanol by using mechanical and ultrasonic mixing. Four different synthesis approaches were used in doping of Ag nanoparticles. The phase, morphology, optical and magnetic properties of the synthesized powders were characterized by using X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope, UV-visible spectrometer (UV-Vis) and vibrating sample magnetometer. Spherical morphology of the Ag nanoparticles was found to deposit on the iron oxide-silica surfaces. The particle size distribution is depending on the synthesis approach used. The UV-Vis absorption peak at 404-410 nm of wavelength confirmed the existence of the Ag nanoparticles.

  7. Influence of different synthesis approach on doping behavior of silver nanoparticles onto the iron oxide-silica coreshell surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mahmed, Norsuria, E-mail: norsuria.mahmed@aalto.fi [Aalto University School of Chemical Technology, Department of Materials Science and Engineering (Finland); Jiang Hua [Aalto University School of Science, Department of Applied Physics (Finland); Heczko, Oleg [Academy of Sciences, Institute of Physics (Czech Republic); Soederberg, Outi; Hannula, Simo-Pekka [Aalto University School of Chemical Technology, Department of Materials Science and Engineering (Finland)

    2012-08-15

    Silver (Ag) nanoparticles with the crystallite size ranging from 13-24 nm were successfully doped onto the surface of iron oxide-silica coreshell particles. In the process, iron oxide particles having a size distribution within 8-19 nm were prepared by using a reverse co-precipitation method followed by the formation of iron oxide-core with silica shell (with 50-150 nm diameter of silica spheres) by using a modified Stoeber method. The reduction of Ag ions was done at room temperature in a solution containing polyvinylpyrrolidone and ethanol by using mechanical and ultrasonic mixing. Four different synthesis approaches were used in doping of Ag nanoparticles. The phase, morphology, optical and magnetic properties of the synthesized powders were characterized by using X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope, UV-visible spectrometer (UV-Vis) and vibrating sample magnetometer. Spherical morphology of the Ag nanoparticles was found to deposit on the iron oxide-silica surfaces. The particle size distribution is depending on the synthesis approach used. The UV-Vis absorption peak at 404-410 nm of wavelength confirmed the existence of the Ag nanoparticles.

  8. Determination of temperature of moving surface by sensitivity analysis

    CERN Document Server

    Farhanieh, B

    2002-01-01

    In this paper sensitivity analysis in inverse problem solutions is employed to estimate the temperature of a moving surface. Moving finite element method is used for spatial discretization. Time derivatives are approximated using Crank-Nicklson method. The accuracy of the solution is assessed by simulation method. The convergence domain is investigated for the determination of the temperature of a solid fuel.

  9. Mechanical Behavior of Ultrafine Gradient Grain Structures Produced via Ambient and Cryogenic Surface Mechanical Attrition Treatment in Iron

    Directory of Open Access Journals (Sweden)

    Heather A. Murdoch

    2015-06-01

    Full Text Available Ambient and cryogenic surface mechanical attrition treatments (SMAT are applied to bcc iron plate. Both processes result in significant surface grain refinement down to the ultrafine-grained regime; the cryogenic treatment results in a 45% greater grain size reduction. However, the refined region is shallower in the cryogenic SMAT process. The tensile ductility of the grain size gradient remains low (<10%, in line with the expected behavior of the refined surface grains. Good tensile ductility in a grain size gradient requires the continuation of the gradient into an undeformed region.

  10. Carbonyl iron powder surface modification of magnetorheological elastomers for vibration absorbing application

    Science.gov (United States)

    Chen, Dong; Yu, Miao; Zhu, Mi; Qi, Song; Fu, Jie

    2016-11-01

    With excellent characteristic of magnetic-control stiffness, magnetorheological elastomer (MRE) is well suited as a spring element of vibration absorber. To improve the vibration attenuation performance of MRE vibration absorbers, this paper expects to improve the mechanical strength and reduce the loss factor of MRE by interface modification. The surface of carbonyl iron powder (CIP) was modified with silica coating by a simple and convenient approach. Several MRE samples, with different proportions of modified CIPs were fabricated under a constant magnetic field. The morphology and composition of modified CIP were characterized by scanning electron microscope and Fourier transform infrared spectra. The results indicated that the modified CIPs were coated with uniform and continuous silica, which can make a better combination between particle and matrix. The tensile strength, magnetorheological properties and the damping properties of the MRE samples were tested by material testing machine and rheometer. The experimental results demonstrated that the loss factor of the MRE which incorporated with modified CIPs decreased markedly, and the tensile strength of such material has been much improved, at the same time this kind of MRE kept high MR effect. It is expected that this MRE material will meet the requirements of vibration absorber.

  11. Hydroxyl radicals induced by quartz particles in lung alveolar macrophages: the role of surface iron

    Institute of Scientific and Technical Information of China (English)

    LI Yi; ZHU Tong; GUO Xinbiao; SHANG Yu

    2006-01-01

    Previous studies have shown that hydroxyl radical generation is a key step in the mechanism of pathogenic process caused by airborne particles to the lung. However, there is no direct evidence for dose-response relationship between airborne particles and hydroxyl radical generation. In this study, hydroxyl radicals generated in lung alveolar macrophages exposed to quartz particles were measured using a highly sensitive capillary electrophoresis-fluorescence detection method. The results demonstrated that quartz particles induced the generation of hydroxyl radical in a dose-dependent manner, and the amount of the hydroxyl radicals was 10-10 mol/106 cells.The viability of alveolar macrophages exposed to quartz particles decreased with the increase of quartz concentration, showing a clear doseresponse relationship. Hydroxyl radical scavenger mannitol could increase the viability of quartz-treated cells, suggesting that hydroxyl radical contributed directly to cell death. In this study this contribution accounted for about 5%-20% of cell death. The hydroxyl radical generating potential was found to be related to surface iron content of the quartz particles.

  12. Fermi surface deformation in a simple iron-based superconductor, FeSe

    Science.gov (United States)

    Coldea, Amalia; Watson, Matthew; Kim, Timur; Haghighirad, Amir; McCollam, Alix; Hoesch, Moritz; Schofield, Andrew

    2015-03-01

    One of the outstanding problems in the field superconductivity is the identification of the normal state out of which superconductivity emerges. FeSe is one of the simplest and most intriguing iron-based superconductors, since in its bulk form it undergoes a structural transition before it becomes superconducting, whereas its single-layer form is believed to be a high-temperature superconductor. The nature of the structural transition, occurring in the absence of static magnetism, is rather unusual and how the electronic structure is stabilized by breaking of the rotational symmetry is the key to understand the superconductivity in bulk FeSe. Here we report angle-resolved photoemission spectroscopy measurements on FeSe that gives direct access to the band structure and orbital-dependent effects. We complement our studies on bulk FeSe with low-temperature angular-dependent quantum oscillation measurements using applied magnetic fields that are sufficiently strong to suppress superconductivity and reach the normal state. These studies reveal a strong deformation of Fermi surface through the structural transition driven by electronic correlations and orbital-dependent effects. . This work was supported by EPSRC, UK (EP/I004475/1), Diamond Light Source, UK and HFML, Nijmegen.

  13. Cell-surface signaling in Pseudomonas: stress responses, iron transport, and pathogenicity.

    Science.gov (United States)

    Llamas, María A; Imperi, Francesco; Visca, Paolo; Lamont, Iain L

    2014-07-01

    Membrane-spanning signaling pathways enable bacteria to alter gene expression in response to extracytoplasmic stimuli. Many such pathways are cell-surface signaling (CSS) systems, which are tripartite molecular devices that allow Gram-negative bacteria to transduce an extracellular stimulus into a coordinated transcriptional response. Typically, CSS systems are composed of the following: (1) an outer membrane receptor, which senses the extracellular stimulus; (2) a cytoplasmic membrane-spanning protein involved in signal transduction from the periplasm to the cytoplasm; and (3) an extracytoplasmic function (ECF) sigma factor that initiates expression of the stimulus-responsive gene(s). Members of genus Pseudomonas provide a paradigmatic example of how CSS systems contribute to the global control of gene expression. Most CSS systems enable self-regulated uptake of iron via endogenous (pyoverdine) or exogenous (xenosiderophores, heme, and citrate) carriers. Some are also implicated in virulence, biofilm formation, and cell-cell interactions. Incorporating insights from the well-characterized alginate regulatory circuitry, this review will illustrate common themes and variations at the level of structural and functional properties of Pseudomonas CSS systems. Control of the expression and activity of ECF sigma factors are central to gene regulation via CSS, and the variety of intrinsic and extrinsic factors influencing these processes will be discussed.

  14. Displaying structural property and inheritance of cast iron surfacing on steel base

    Science.gov (United States)

    Shveev, I. A.

    2016-06-01

    Graphite inclusions heredity in deposited layer from remelted special cast iron billets was established. The possibility of controlling the structural state and the quality of the deposited layer due to technological parameters of welding and heat treatment of parts is shown. Ways of improving cast iron wear resistance durability are proposed.

  15. Magnetic Particle Spectroscopy Reveals Dynamic Changes in the Magnetic Behavior of Very Small Superparamagnetic Iron Oxide Nanoparticles During Cellular Uptake and Enables Determination of Cell-Labeling Efficacy.

    Science.gov (United States)

    Poller, Wolfram C; Löwa, Norbert; Wiekhorst, Frank; Taupitz, Matthias; Wagner, Susanne; Möller, Konstantin; Baumann, Gert; Stangl, Verena; Trahms, Lutz; Ludwig, Antje

    2016-02-01

    In vivo tracking of nanoparticle-labeled cells by magnetic resonance imaging (MRI) crucially depends on accurate determination of cell-labeling efficacy prior to transplantation. Here, we analyzed the feasibility and accuracy of magnetic particle spectroscopy (MPS) for estimation of cell-labeling efficacy in living THP-1 cells incubated with very small superparamagnetic iron oxide nanoparticles (VSOP). Cell viability and proliferation capacity were not affected by the MPS measurement procedure. In VSOP samples without cell contact, MPS enabled highly accurate quantification. In contrast, MPS constantly overestimated the amount of cell associated and internalized VSOP. Analyses of the MPS spectrum shape expressed as harmonic ratio A₅/A₃ revealed distinct changes in the magnetic behavior of VSOP in response to cellular uptake. These changes were proportional to the deviation between MPS and actual iron amount, therefore allowing for adjusted iron quantification. Transmission electron microscopy provided visual evidence that changes in the magnetic properties correlated with cell surface interaction of VSOP as well as with alterations of particle structure and arrangement during the phagocytic process. Altogether, A₅/A₃-adjusted MPS enables highly accurate, cell-preserving VSOP quantification and furthermore provides information on the magnetic characteristics of internalized VSOP.

  16. Genotoxicity assessment of magnetic iron oxide nanoparticles with different particle sizes and surface coatings

    Science.gov (United States)

    Liu, Yanping; Xia, Qiyue; Liu, Ying; Zhang, Shuyang; Cheng, Feng; Zhong, Zhihui; Wang, Li; Li, Hongxia; Xiao, Kai

    2014-10-01

    Magnetic iron oxide nanoparticles (IONPs) have been widely used for various biomedical applications such as magnetic resonance imaging and drug delivery. However, their potential toxic effects, including genotoxicity, need to be thoroughly understood. In the present study, the genotoxicity of IONPs with different particle sizes (10, 30 nm) and surface coatings (PEG, PEI) were assessed using three standard genotoxicity assays, the Salmonella typhimurium reverse mutation assay (Ames test), the in vitro mammalian chromosome aberration test, and the in vivo micronucleus assay. In the Ames test, SMG-10 (PEG coating, 10 nm) showed a positive mutagenic response in all the five test bacterial strains with and without metabolic activation, whereas SEI-10 (PEI coating, 10 nm) showed no mutagenesis in all tester strains regardless of metabolic activation. SMG-30 (PEG coating, 30 nm) was not mutagenic in the absence of metabolic activation, and became mutagenic in the presence of metabolic activation. In the chromosomal aberration test, no increase in the incidence of chromosomal aberrations was observed for all three IONPs. In the in vivo micronucleus test, there was no evidence of increased micronuclei frequencies for all three IONPs, indicating that they were not clastogenic in vivo. Taken together, our results demonstrated that IONPs with PEG coating exhibited mutagenic activity without chromosomal and clastogenic abnormalities, and smaller IONPs (SMG-10) had stronger mutagenic potential than larger ones (SMG-30); whereas, IONPs with SEI coating (SEI-10) were not genotoxic in all three standard genotoxicity assays. This suggests that the mutagenicity of IONPs depends on their particle size and surface coating.

  17. Genotoxicity assessment of magnetic iron oxide nanoparticles with different particle sizes and surface coatings.

    Science.gov (United States)

    Liu, Yanping; Xia, Qiyue; Liu, Ying; Zhang, Shuyang; Cheng, Feng; Zhong, Zhihui; Wang, Li; Li, Hongxia; Xiao, Kai

    2014-10-24

    Magnetic iron oxide nanoparticles (IONPs) have been widely used for various biomedical applications such as magnetic resonance imaging and drug delivery. However, their potential toxic effects, including genotoxicity, need to be thoroughly understood. In the present study, the genotoxicity of IONPs with different particle sizes (10, 30 nm) and surface coatings (PEG, PEI) were assessed using three standard genotoxicity assays, the Salmonella typhimurium reverse mutation assay (Ames test), the in vitro mammalian chromosome aberration test, and the in vivo micronucleus assay. In the Ames test, SMG-10 (PEG coating, 10 nm) showed a positive mutagenic response in all the five test bacterial strains with and without metabolic activation, whereas SEI-10 (PEI coating, 10 nm) showed no mutagenesis in all tester strains regardless of metabolic activation. SMG-30 (PEG coating, 30 nm) was not mutagenic in the absence of metabolic activation, and became mutagenic in the presence of metabolic activation. In the chromosomal aberration test, no increase in the incidence of chromosomal aberrations was observed for all three IONPs. In the in vivo micronucleus test, there was no evidence of increased micronuclei frequencies for all three IONPs, indicating that they were not clastogenic in vivo. Taken together, our results demonstrated that IONPs with PEG coating exhibited mutagenic activity without chromosomal and clastogenic abnormalities, and smaller IONPs (SMG-10) had stronger mutagenic potential than larger ones (SMG-30); whereas, IONPs with SEI coating (SEI-10) were not genotoxic in all three standard genotoxicity assays. This suggests that the mutagenicity of IONPs depends on their particle size and surface coating.

  18. Determination of ocean surface wave shape from forward scattered sound.

    Science.gov (United States)

    Walstead, Sean P; Deane, Grant B

    2016-08-01

    Forward scattered sound from the ocean surface is inverted for wave shape during three periods: low wind, mix of wind and swell, and stormy. Derived wave profiles are spatially limited to a Fresnel region at or near the nominal surface specular reflection point. In some cases, the surface wave profiles exhibit unrealistic temporal and spatial properties. To remedy this, the spatial gradient of inverted waves is constrained to a maximum slope of 0.88. Under this global constraint, only surface waves during low wind conditions result in a modeled surface multipath that accurately matches data. The power spectral density of the inverted surface wave field saturates around a frequency of 8 Hz while upward looking SONAR saturates at 1 Hz. Each shows a high frequency spectral slope of -4 that is in agreement with various empirical ocean wave spectra. The improved high frequency resolution provided by the scattering inversion indicates that it is possible to remotely gain information about high frequency components of ocean waves. The inability of the inversion algorithm to determine physically realistic surface waves in periods of high wind indicates that bubbles and out of plane scattering become important in those operating scenarios.

  19. Experimental determination of the electrical resistivity of iron at Earth’s core conditions

    Science.gov (United States)

    Ohta, Kenji; Kuwayama, Yasuhiro; Hirose, Kei; Shimizu, Katsuya; Ohishi, Yasuo

    2016-06-01

    Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth’s core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth’s core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch-Grüneisen law, which considers only the electron-phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth’s core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core.

  20. NUMERICAL APPROACH TO DETERMINING INSTANTANEOUS CONTACT REGION FOR CONJUGATE SURFACES

    Institute of Scientific and Technical Information of China (English)

    WANG Taiyong; LI Jingcai; HE Gaiyun; FAN Shengbo; HAO Yongjiang

    2008-01-01

    According to the defect of traditional method of determining instantaneous contact regions for conjugate surfaces, a numerical approach to the determination is proposed. A local coordinate system is built by using the surface unit tangent and unit normal at the contact point. Considering that the gap forming the boundary of instantaneous contact region in the direction of the common normal vectors is given, a system of nonlinear equations is built to find the instantaneous contact boundary in local coordinate system, a modified Powell's hybrid algorithm of finite-difference approximation to the Jacobian used to solve the system. The new method simplifies the task of determining instantaneous contact regions without calculating curvature and relative curvature. The validity of the proposed approach is verified by an example of hypoid gears.

  1. Site Determination and Magnetism of Mn Doping in Protein Encapsulated Iron Oxide Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pool, V.; Klem, M.; Jolley, J.; Arenholz, E.A.; Douglas, T.; Young, M.; Idzerda, Y.U.

    2010-01-11

    Soft-X-ray absorption spectroscopy, soft-X-ray magnetic circular dichroism, and alternating current magnetic susceptibility were performed on 6.7 nm iron oxide nanoparticles doped with (5-33%) Mn grown inside the horse-spleen ferritin protein cages and compared to similarly protein encapsulated pure Fe-oxide and Mn-oxide nanoparticles to determine the site of the Mn dopant and to quantify the magnetic behavior with varying Mn concentration. The Mn dopant is shown to substitute preferentially as Mn{sup +2} and prefers the octahedral site in the defected spinel structure. The Mn multiplet structure for the nanoparticles is simpler than for the bulk standards, suggesting that the nanoparticle lattices are relaxed from the distortions present in the bulk. Addition of Mn is found to alter the host Fe-oxide lattice from a defected ferrimagnetic spinel structure similar to {gamma}-Fe{sub 2}O{sub 3} to an non-ferromagnetic spinel structure with a local Fe environment similar to Fe{sub 3}O{sub 4}.

  2. Iron oxide nanoparticles modified with oleic acid: Vibrational and phase determination

    Science.gov (United States)

    Soares, Paula P.; Barcellos, Geórgia S.; Petzhold, Cesar L.; Lavayen, Vladimir

    2016-12-01

    A simple path methodology to detect the phase composition of iron oxide nanoparticles modified with oleic acid based on vibrational spectroscopy is present here and applied on three different nanoparticles prepared by co-precipitation method. Firstly, the phase composition, magnetite, maghemite, and hematite, is determined using a reference intensity ratio methodology on X-ray diffraction pattern. Also, the size of each sample was calculated by Scherrer equation. Scanning, transmission electron microscopy, microanalysis and electron diffraction show a core magnetite particles size of around 10 nm for all particles. Based on lattice vibrations, we find a concentration of around 80% of magnetite and a hematite phase lower than 5%. Whereas, the magnetite composition from X-ray diffraction shows 76%. We also investigate the metal-organic interaction and disorder degree of organic molecule conformation by infrared and Raman spectroscopy analysis. Hematite lattice vibrations show more alterations as it interacts with the organic acid. Finally, magnetic measurements at room temperature of the modified particles, suggest a superparamagnetic behavior and high saturation magnetization.

  3. Determination of electronic ground state properties of a dinuclear iron(II) spin crossover complex

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, T. O., E-mail: thbauer@rhrk.uni-kl.de [University of Kaiserslautern, Department of Physics (Germany); Schmitz, M.; Graf, M.; Kelm, H.; Krüger, H.-J. [University of Kaiserslautern, Department of Chemistry (Germany); Schünemann, V. [University of Kaiserslautern, Department of Physics (Germany)

    2016-12-15

    The dinuclear complex [(Fe(L-N{sub 4}Me{sub 2})){sub 2}(BiBzIm)](ClO{sub 4}){sub 2}⋅2EtCN (1) has been investigated by Mössbauer spectroscopy carried out in the temperature range from 5 to 150 K with externally applied magnetic fields of up to B = 5 T. By means of a consistent simulation of all experimental data sets within the Spin Hamiltonian formalism, the zero-field splitting D and the rhombicity parameter E/D of the ferrous high-spin (HS) site in this complex was determined to be D = −15.0 ± 1.0 cm{sup −1} and E/D = 0.33 respectively. The sign of the quadrupole splitting of the HS site is positive which indicates that this iron site of the dinuclear complex 1 has an electronic ground state with the d{sub xy} orbital being twofold occupied.

  4. Behaviour of Self-Standing CVD Diamond Film with Different Dominant Crystalline Surfaces in Thermal-Iron Plate Polishing

    Institute of Scientific and Technical Information of China (English)

    CHEN Guang-Chao; ZHOU Zu-Yuan; LI Bin; ZHOU You-Liang; J. Askri; LI Cheng-Ming; TANG Wei-Zhong; TONG Yu-Mei; LU Fan-Xiu

    2006-01-01

    @@ Self-standing CVD diamond films with different dominant crystalline surfaces are polished by the thermal-iron plate polishing method. The influence of the dominant crystalline surfaces on polishing efficiency is investigated by measuring the removal rate and final roughness. The smallest rms roughness of 0.14μm is measured with smallest removal rate in the films with the initial (220) dominant crystalline surface. Activation energy for the polishing is analysed by the Arrhenius relation. It is found that the values are 170kJ/mol, 222kJ/mol and 214kJ/mol for the film with t hree different dominant crystalline surfaces. Based on these values, the polishing cause is regarded as the graphitization-controlling process. In the experiment, we find that transformation of the dominant crystalline surfaces from (111) to (220) always appears in the polishing process when we polish the (111) dominant surface.

  5. Cobalt and iron segregation and nitride formation from nitrogen plasma treatment of CoFeB surfaces

    Science.gov (United States)

    Mattson, E. C.; Michalak, D. J.; Veyan, J. F.; Chabal, Y. J.

    2017-02-01

    Cobalt-iron-boron (CoFeB) thin films are the industry standard for ferromagnetic layers in magnetic tunnel junction devices and are closely related to the relevant surfaces of CoFe-based catalysts. Identifying and understanding the composition of their surfaces under relevant processing conditions is therefore critical. Here we report fundamental studies on the interaction of nitrogen plasma with CoFeB surfaces using infrared spectroscopy, x-ray photoemission spectroscopy, and low energy ion scattering. We find that, upon exposure to nitrogen plasma, clean CoFeB surfaces spontaneously reorganize to form an overlayer comprised of Fe2N3 and BN, with the Co atoms moved well below the surface through a chemically driven process. Subsequent annealing to 400 °C removes nitrogen, resulting in a Fe-rich termination of the surface region.

  6. A new spectrophotometric method for the determination of total and ferric iron in rain water at the ppb level

    Energy Technology Data Exchange (ETDEWEB)

    Patel, K.S.; Shukla, A.; Goswami, A.; Chandavanshi, S.K. [School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur (India); Hoffmann, P. [Materials and Geo Science, Chemical Analytics, Technical Univ. Darmstadt (Germany)

    2001-03-01

    A new, simple, selective and sensitive spectrophotometric procedure for the on-site quantification of iron at nano-gram levels in atmospheric precipitations, i.e. rain as sample source is described. It is based on the color reaction of Fe{sup 3+} with SCN{sup -} ions in the presence of a cationic surfactant, i.e. cetylpyridinium chloride (CPC), in strong HCl solution, and subsequent extraction of the complex with N-octylacetamide into toluene or chloroform. The apparent molar absorptivity of the complex is 2.60 x 10{sup 5}L mol {sup -1}cm {sup -1} at {lambda}{sub max} = 480 nm at an enrichment factor (EF) of 10. The detection limit (causing higher absorbance than the sum of the blank absorbance (0.009) and 3 SD) is 5 ng mL {sup -1} Fe. Ions commonly associated with iron did not interfere in the present method. The effect of analytical variables, i.e. amount and type of the reagents, acidity, solvent, temperature, dilution, etc., in the determination of iron are discussed. The validity of the present method is checked with GF-AAS. The method has been applied to the determination of iron at the ppb level in rain water samples. (orig.)

  7. Simultaneous determination of trace iron and aluminum by catalytic spectrophotometry based on a novel oxidation reaction of xylene cyanol FF.

    Science.gov (United States)

    Cai, Longfei; Xu, Chunxiu

    2008-06-01

    A new, simple, sensitive and selective method for the simultaneous determination of trace iron and aluminum by catalytic spectrophotometry was presented, based on the catalytic effects of iron and aluminum on the discoloring reaction of xylene cyanol FF proceeded by hydrogen peroxide and potassium periodate in weak nitric acid medium. No catalytic effect was obtained in the presence of hydrogen peroxide or potassium periodate only. With the conditional rate constants determined in reaction systems catalyzed by Al or Fe only, the concentrations of Fe and Al in the samples can be calculated. The method was applied to the simultaneous determination of trace Fe and Al in tap water, lake water, river water and tea leaves without separation and preconcentration.

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

    Science.gov (United States)

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

    2015-04-28

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

  9. Bimetallic nickel-iron nanoparticles for groundwater decontamination: effect of groundwater constituents on surface deactivation.

    Science.gov (United States)

    Han, Yanlai; Yan, Weile

    2014-12-01

    The incorporation of catalytic metals on iron nanoparticles to form bimetallic nanoparticles (BNPs) generates a class of highly reactive materials for degrading chlorinated hydrocarbons (e.g., trichloroethylene, TCE) in groundwater. Successful implementation of BNPs to groundwater decontamination relies critically on the stability of surface reactive sites of BNPs in groundwater matrices. This study investigated the effect of common groundwater solutes on TCE reduction with Ni-Fe (with Ni at 2 wt.%) bimetallic nanoparticles (herein denoted as Ni-Fe BNPs). Batch experiments involving pre-exposing the nanoparticles to various groundwater solutions for 24 h followed by reactions with TCE solutions were conducted. The results suggest that the deactivation behavior of Ni-Fe BNPs differs significantly from that of the well-studied Pd-Fe BNPs. Specifically, Ni-Fe BNPs were chemically stable in pure water. Mild reduction in TCE reaction rates were observed for Ni-Fe BNPs pre-exposed to chloride (Cl(-)), bicarbonate (HCO3(-)), sulfite (SO3(2-)) and humic acid solutions. Nitrate (NO3(-)), sulfate (SO4(2-)) and phosphate (HPO4(2-)) may cause moderate to severe deactivation at elevated concentrations (>1 mM). Product analysis and surface chemistry investigations using high-resolution X-ray photoelectron spectroscopy (HR-XPS) reveal that NO3(-) decreased particle reactivity mainly due to progressive formation of passivating oxides, whereas SO4(2-) and phosphate elicited rapid deactivation as a result of specific poisoning of the surface nickel sites. At similar levels, phosphate is the most potent deactivation agent among the solutes examined in this study. While our findings point out the desirable quality of Ni-Fe nanoparticles, particularly their greater electrochemical stability compared to Pd-Fe BNPs, its susceptibility to chemical poisoning at high levels of complexing ligands is also noted. Groundwater chemistry is therefore an important factor to consider when

  10. Optimization of pulsed Nd:YAG laser melting of gray cast iron at different spot sizes for enhanced surface properties

    Science.gov (United States)

    Zulhishamuddin, A. R.; Aqida, S. N.; Rahim, E. A.

    2016-10-01

    This paper presents a laser surface modification process of gray cast iron using different laser spot size with an aims to eliminate graphite phase and achieve minimum surface roughness and maximum depth of molten zone and microhardness properties. The laser processing was conducted using JK300HPS Nd:YAG twin lamp laser source pulse TEM00 mode, 50 W average power, 1064 nm wavelength and different laser spot sizes of 1.0 mm, 1.2 mm, 1.4 mm and 1.7 mm. Three controlled parameter were peak power (Pp), pulse repetition frequency (PRF) and traverse speed (v). Increasing spot size the parameter setting where peak power is increased and pulse repetition frequency and traverse speed is decreased. The modified surface of laser surface melting was characterized for metallographic study, surface roughness and hardness. Metallographic study and surface morphology were conducted using optical microscope while hardness properties were measured using Vickers scale. Surface roughness was measured using a 2D stylus profilometer. From metallographic study, the graphite phase was totally eliminated from the molten zone and formed white zone. This phenomenon affected hardness properties of the modified surface where maximum hardness of 955.8 HV0.1 achieved. Optimization of laser surface modification was conducted for minimum surface roughness and maximum depth of modified layer and hardness properties. From the optimization, the higher desirability is 0.902. The highest depth of molten zone obtain from spot size 1.4 mm at 132 µm and the highest hardness is 989 HV0.1 at laser's spot size 1.0 mm. The surface roughness increased when the spot size increased from 3.10 µm to 7.31 µm. These finding indicate potential application of enhanced gray cast iron in high wear resistance automotive components such as cylinder liner and break disc.

  11. Determination of iron and aluminum based on the catalytic effect on the reaction of xylene cyanol FF with hydrogen peroxide and potassium periodate

    OpenAIRE

    Cai, Longfei; Xu, Chunxiu

    2011-01-01

    A simple, sensitive and selective method for the simultaneous determination of trace iron and aluminum by catalytic spectrophotometry is presented. This method is based on the catalytic effects of iron and aluminum on the reaction of xylene cyanol FF with hydrogen peroxide and potassium periodate. Both iron and aluminum did not show catalytic effects on the oxidation reaction of xylene cyanol FF in the presence of either hydrogen peroxide or potassium periodate. However, significant catalytic...

  12. Distribution of iron and titanium on the lunar surface from lunar prospector gamma ray spectra

    Science.gov (United States)

    Prettyman, T.

    2001-01-01

    Gamma ray pulse height spectra acquired by the Lunar Prospector (LP) Gamma-Ray Spectrometer (GRS) contain information on the abundance of major elements in the lunar surface, including O, Si, Ti, Al, Fe, Mg, Ca, K, and Th. With the exception of Th and K, prompt gamma rays produced by cosmic ray interactions with surface materials are used to determine elemental abundance. Most of these gamma rays are produced by inelastic scattering of fast neutrons and by neutrons and by neutron capture. The production of neutron-induced gamma rays reaches a maximum deep below the surface (e.g. approximately 140g/cm2 for inelastic scattering and approximately 50 g/cm2 for capture). Consequently, gamma rays sense the bulk composition of lunar materials, in contrast to optical methods (e.g. Clementine Spectral Reflectance (CSR)), which only sample the top few microns. Because most of the gamma rays are produced deep beneath the surface, few escape unscattered and the continuum of scattered gamma rays dominates the spectrum. In addition, due to the resolution of the spectrometer, there are few well-isolated peaks and peak fitting algorithms must be used to deconvolve the spectrum on order to determine the contribution of individual elements.

  13. Investigation of the tribology behaviour of the graphene nanosheets as oil additives on textured alloy cast iron surface

    Science.gov (United States)

    Zheng, Dan; Cai, Zhen-bing; Shen, Ming-xue; Li, Zheng-yang; Zhu, Min-hao

    2016-11-01

    Tribological properties of graphene nanosheets (GNS) as lubricating oil additives on textured surfaces were investigated using a UMT-2 tribotester. The lubricating fluids keeping a constant temperature of 100 °C were applied to a GCr15 steel ball and an RTCr2 alloy cast iron plate with various texture designs (original surface, dimple density of 22.1%, 19.6% and 44.2%). The oil with GNS adding showed good tribological properties (wear reduced 50%), especially on the textured surfaces (the reduction in wear was high at over 90%). A combined effect between GNS additives and laser surface texturing (LST) was revealed, which is not a simple superposition of the two factors mentioned. A mechanism is proposed to explain for these results -the graphene layers sheared at the sliding contact interfaces, and form a protective film, which is closely related with the GNS structures and surface texture patterns.

  14. Final Report: The Impact of Carbonate on Surface Protonation, Electron Transfer and Crystallization Reactions in Iron Oxide Nanoparticles and Colloids

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David Adams [The University of Alabama

    2013-07-02

    This project addresses key issues of importance in the geochemical behavior of iron oxides and in the geochemical cycling of carbon and iron. For Fe, we are specifically studying the influence of carbonate on electron transfer reactions, solid phase transformations, and the binding of carbonate to reactive sites on the edges of particles. The emphasis on carbonate arises because it is widely present in the natural environment, is known to bind strongly to oxide surfaces, is reactive on the time scales of interest, and has a speciation driven by acid-base reactions. The geochemical behavior of carbonate strongly influences global climate change and CO{sub 2} sequestration technologies. Our goal is to answer key questions with regards to specific site binding, electron transfer reactions, and crystallization reactions of iron oxides that impact both the geochemical cycling of iron and CO{sub 2} species. Our work is focused on the molecular level description of carbonate chemistry in solution including the prediction of isotope fractionation factors. We have also done work on critical atmospheric species.

  15. Application of Response Surface Methodology on Leaching of Iron from Partially Laterised Khondalite Rocks: A Bauxite Mining Waste

    Science.gov (United States)

    Swain, Ranjita; Bhima Rao, R.

    2017-08-01

    In the present investigation, response surface methodology (RSM) is used for a quadratic model that continuously controls the process parameters. This model is used to optimize the removal of iron oxide from Partially Laterised Khondalite (PLK) rocks which is influenced by several independent variables namely acid concentration, time and temperature. Second order response functions are produced for leaching of iron oxide from PLK rocks-a bauxite mining waste. In RSM, Box-Behnken design is used for the process optimization to achieve maximum removal of iron oxide. The influence of the process variables of leaching of iron oxide is presented in the form of 3-D response graphs. The results of this investigation reveals that 3 M hydrochloric acid concentration, 240 min time and 373 K temperature are found to be the best conditions for removal of 99% Fe2O3. The product obtain at this condition contain 80% brightness which is suitable for ceramic and filler industry applications. The novelity of the work is that the waste can be a value added product after suitable physical beneficiation and chemical treatment.

  16. Contribution of Iron and Aluminum Oxides to Electrokinetic Characteristics of Variable Charge Soils in Relation to Surface Charge

    Institute of Scientific and Technical Information of China (English)

    ZHANGHONG; ZHANGXIAO-NIAN

    1992-01-01

    The contribution of iron and aluminum oxides to electrokinetic characteristics of variable charge soils was studied through determination of electrophoretic mobilities of the red soils treated with either removal of iron oxides or coating of aluminum oxides,and of those deferrated under natural conditions.After removal of the iron oxides,zeta potentials of the latosol and the red earth decreased obviously with a shift of IEP to a lower pH,from 6.4 to 5.3 and 4.1 to 2.4 for the former and the latter,respectively,and the electrokinetic change for the latosol was greater than for the red earth.Zeta potentials of the kaolinite sample increased markedly after coated with iron oxides.The striking effect of iron oxides on electrokinetix properties of the soils was also demonstrated by the electrokinetic differences between the samples from the red and white zones of a plinthitic horizon formed naturally,and between the samples from the gley and bottom horizons of a paddy soil derived from a red earth.The coatings of aluminum oxides on the latosol and the yellow earth made their zeta potentials rise pronouncedly and their IEFs move toward higher pHs,from 6.2 to 6.8 and 4.3 to 5.3 for the former and the latter,respectively.The samples with different particle sizes also exhibited some electrokinetic variation.The experiment showed that the effects of iron and aluminum oxides were closely related to the pH and type of the soils.

  17. DETERMINATION OF GLACIER SURFACE AREA USING SPACEBORNE SAR IMAGERY

    OpenAIRE

    Fang, L.; Maksymiuk, O.; Schmitt, M.; Stilla, U.

    2013-01-01

    Glaciers are very important climate indicators. Although visible remote sensing techniques can be used to extract glacier variations effectively and accurately, the necessary data are depending on good weather conditions. In this paper, a method for determination of glacier surface area using multi-temporal and multi-angle high resolution TerraSAR-X data sets is presented. We reduce the "data holes" in the SAR scenes affected by radar shadowing and specular backscattering of smooth i...

  18. Improvement of electrochemical activity of LiMnPO4-based cathode by surface iron enrichment

    Science.gov (United States)

    Xu, Xiaoyue; Wang, Tao; Bi, Yujing; Liu, Meng; Yang, Wenchao; Peng, Zhe; Wang, Deyu

    2017-02-01

    LiMnPO4 has attracted massive interests due to its appropriate redox potential and the success of its iron comparative in the lithium ion batteries. The bulk substitution has been widely used to address the poor electrochemical activity of LiMnPO4, which is much lower than that of LiFePO4. In this work, we compare the performance of the core-shell structure and the homogeneous substitution with the same Mn/Fe molar ratio of LiMn0.8Fe0.2PO4. The core-shell phosphate material after carbon coating is composed of a core part of quasi-single LiMnPO4 phase, and a 3-4 nm shell layer of quasi-single LiFePO4-phase, separated by the phase boundary with 1-2 nm thickness. It is interesting to reveal that the core-shell samples exhibit capacities of 156.4, 144.5, 128.2 mAh g-1 under 0.1C, 1C and 5C respectively, which are 5-10% higher than that of the homogenous substituted LiMn0.8Fe0.2PO4 at the corresponding rates, while both of these samples present excellent cyclic stability, still retaining ∼95% of the initial capacities after 1000 cycles under 1C discharging rate. Our results demonstrate that the main reason for LiMnPO4's poor electrochemical activity should be emphasized on the surface polarization, whereas the tardiness on bulk transportation is not as serious as it was presumed.

  19. Free radical generation in the toxicity of inhaled mineral particles: the role of iron speciation at the surface of asbestos and silica.

    Science.gov (United States)

    Fenoglio, I; Prandi, L; Tomatis, M; Fubini, B

    2001-01-01

    Free radical generation at the particle/biological fluid interface is one of the chemical processes that contributes to pathogenicity. In order to investigate the role played by iron, fibres of crocidolite asbestos have been modified by thermal treatments to alter their surface iron content. Two radical mechanisms, HO* from H2O2 and cleavage of a C-H bond, which are both active on the original fibres, have been tested on the modified fibres. C-H cleavage is dependent on Fe(II) abundance and location and is suppressed by surface oxidation while HO* release appears independent of the oxidation state of iron. Quartz specimens with different levels of iron impurities have been tested in a similar manner. A commercially available quartz (Min-U-Sil 5) containing trace levels of iron is also active in both tests, but reactivity is not fully suppressed by treatment with desferrioxamine, which should remove/inactivate iron. The radical yield attained is close to the level produced by a pure quartz dust, suggesting the presence of active sites other than iron. Ascorbic acid reacts with both crocidolite and quartz, with subsequent depletion of the level of antioxidant defences when particle deposition occurs in the lung lining layer. Following treatment with ascorbic acid the radical yield increases with quartz, but decreases with asbestos. Selective removal of iron and silicon from the surface may account for the differences in behaviour of the two particulates.

  20. Design and stabilisation of a high area iron molybdate surface for the selective oxidation of methanol to formaldehyde.

    Science.gov (United States)

    Chapman, Stephanie; Brookes, Catherine; Bowker, Michael; Gibson, Emma K; Wells, Peter P

    2016-07-04

    The performance of Mo-enriched, bulk ferric molybdate, employed commercially for the industrially important reaction of the selective oxidation of methanol to formaldehyde, is limited by a low surface area, typically 5-8 m(2) g(-1). Recent advances in the understanding of the iron molybdate catalyst have focused on the study of MoOx@Fe2O3 (MoOx shell, Fe2O3 core) systems, where only a few overlayers of Mo are present on the surface. This method of preparing MoOx@Fe2O3 catalysts was shown to support an iron molybdate surface of higher surface area than the industrially-favoured bulk phase. In this research, a MoOx@Fe2O3 catalyst of even higher surface area was stabilised by modifying a haematite support containing 5 wt% Al dopant. The addition of Al was an important factor for stabilising the haematite surface area and resulted in an iron molybdate surface area of ∼35 m(2) g(-1), around a 5 fold increase on the bulk catalyst. XPS confirmed Mo surface-enrichment, whilst Mo XANES resolved an amorphous MoOx surface monolayer supported on a sublayer of Fe2(MoO4)3 that became increasingly extensive with initial Mo surface loading. The high surface area MoOx@Fe2O3 catalyst proved amenable to bulk characterisation techniques; contributions from Fe2(MoO4)3 were detectable by Raman, XAFS, ATR-IR and XRD spectroscopies. The temperature-programmed pulsed flow reaction of methanol showed that this novel, high surface area catalyst (3ML-HSA) outperformed the undoped analogue (3ML-ISA), and a peak yield of 94% formaldehyde was obtained at ∼40 °C below that for the bulk Fe2(MoO4)3 phase. This work demonstrates how core-shell, multi-component oxides offer new routes for improving catalytic performance and understanding catalytic activity.

  1. Determination of the photoelectron reference plane in nanostructured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lobo-Checa, Jorge; Mugarza, Aitor [Centre d' Investigacio en Nanociencia i Nanotecnologia, CIN2 (CSIC-ICN), Esfera UAB, Campus de la UAB, 08193-Bellaterra (Spain); Ortega, Jose Enrique [Dpto Fisica Aplicada I, Universidad del PaIs Vasco, E-20018 San Sebastian (Spain); Michel, Enrique G, E-mail: jorge.lobo@cin2.es [Dpto de Fisica de la Materia Condensada and Instituto Universitario de Ciencia de Materiales ' Nicolas Cabrera' , Universidad Autonoma de Madrid, 28049 Madrid (Spain)

    2011-10-15

    In angle-resolved photoemission (ARPES) from crystalline solids, wave-vector conservation applies to the two-dimensional (2D) surface, which may thus be defined as the reference plane in ARPES. We investigate whether such reference varies for photoemitted electrons in nanometer-sized systems that expose different crystal planes. To this aim, we exploit the structural tunability of the Ag/Cu(223) system which is capable of offering surfaces with periodic arrays of nanofacets of varying size and orientation. A thorough, photon-energy-dependent analysis of the surface states confined to such nanostructures is performed comparing different reference planes for photoemitted electrons. Assuming the premise that k{sub ||} must be a good quantum number for 2D states, we conclude that the (final state) photoelectron reference direction is not the average optical direction but the local facet that confines the (initial state) surface electrons. Moreover, in the general case of nanostructured systems with uneven surfaces, we show how the photoelectron reference plane can be empirically determined through such a photon-energy-dependent ARPES analysis. (paper)

  2. The Vacuolar Manganese Transporter MTP8 Determines Tolerance to Iron Deficiency-Induced Chlorosis in Arabidopsis.

    Science.gov (United States)

    Eroglu, Seckin; Meier, Bastian; von Wirén, Nicolaus; Peiter, Edgar

    2016-02-01

    Iron (Fe) deficiency is a widespread nutritional disorder on calcareous soils. To identify genes involved in the Fe deficiency response, Arabidopsis (Arabidopsis thaliana) transfer DNA insertion lines were screened on a high-pH medium with low Fe availability. This approach identified METAL TOLERANCE PROTEIN8 (MTP8), a member of the Cation Diffusion Facilitator family, as a critical determinant for the tolerance to Fe deficiency-induced chlorosis, also on soil substrate. Subcellular localization to the tonoplast, complementation of a manganese (Mn)-sensitive Saccharomyces cerevisiae yeast strain, and Mn sensitivity of mtp8 knockout mutants characterized the protein as a vacuolar Mn transporter suitable to prevent plant cells from Mn toxicity. MTP8 expression was strongly induced on low-Fe as well as high-Mn medium, which were both strictly dependent on the transcription factor FIT, indicating that high-Mn stress induces Fe deficiency. mtp8 mutants were only hypersensitive to Fe deficiency when Mn was present in the medium, which further suggested an Mn-specific role of MTP8 during Fe limitation. Under those conditions, mtp8 mutants not only translocated more Mn to the shoot than did wild-type plants but suffered in particular from critically low Fe concentrations and, hence, Fe chlorosis, although the transcriptional Fe deficiency response was up-regulated more strongly in mtp8. The diminished uptake of Fe from Mn-containing low-Fe medium by mtp8 mutants was caused by an impaired ability to boost the ferric chelate reductase activity, which is an essential process in Fe acquisition. These findings provide a mechanistic explanation for the long-known interference of Mn in Fe nutrition and define the molecular processes by which plants alleviate this antagonism.

  3. The iron budget in ocean surface waters in the 20th and 21st centuries: projections by the Community Earth System Model version 1

    Directory of Open Access Journals (Sweden)

    K. Misumi

    2013-05-01

    Full Text Available We investigated the simulated iron budget in ocean surface waters in the 1990s and 2090s using the Community Earth System Model version 1 and the Representative Concentration Pathway 8.5 future CO2 emission scenario. We assumed that exogenous iron inputs did not change during the whole simulation period; thus, iron budget changes were attributed solely to changes in ocean circulation and mixing in response to projected global warming. The model simulated the major features of ocean circulation and dissolved iron distribution for the present climate reasonably well. Detailed iron budget analysis revealed that roughly 70% of the iron supplied to surface waters in high-nutrient, low-chlorophyll (HNLC regions is contributed by ocean circulation and mixing processes, but the dominant supply mechanism differed in each HNLC region: vertical mixing in the Southern Ocean, upwelling in the eastern equatorial Pacific, and deposition of iron-bearing dust in the subarctic North Pacific. In the 2090s, our model projected an increased iron supply to HNLC surface waters, even though enhanced stratification was predicted to reduce iron entrainment from deeper waters. This unexpected result could be attributed largely to changes in the meridional overturning and gyre-scale circulations that intensified the advective supply of iron to surface waters, especially in the eastern equatorial Pacific. The simulated primary and export productions in the 2090s decreased globally by 6% and 13%, respectively, whereas in the HNLC regions, they increased by 11% and 6%, respectively. Roughly half of the elevated production could be attributed to the intensified iron supply. The projected ocean circulation and mixing changes are consistent with recent observations of responses to the warming climate and with other Coupled Model Intercomparison Project model projections. We conclude that future ocean circulation and mixing changes will likely elevate the iron supply to HNLC

  4. Determination of the total iron content of used lubricating oils by atomic-absorption with use of emulsions.

    Science.gov (United States)

    Salvador, A; de la Guardia, M; Berenguer, V

    1983-12-01

    A new method is proposed for the determination of the total iron content of used lubricating oils. It is based on treatment of the samples with a mixture of hydrofluoric and nitric acids (without destruction of the organic matter) and emulsification, followed by atomic-absorption measurement. This allows the use of aqueous standards and provides a simple, rapid, inexpensive and accurate method, that is not affected by the particle size of the solids in the oil.

  5. Towards advanced structural analysis of iron oxide clusters on the surface of γ-Al2O3 using EXAFS

    Science.gov (United States)

    Boubnov, Alexey; Roppertz, Andreas; Kundrat, Matthew D.; Mangold, Stefan; Reznik, Boris; Jacob, Christoph R.; Kureti, Sven; Grunwaldt, Jan-Dierk

    2016-11-01

    Iron oxide centres are structurally investigated in 0.1% Fe/γ-Al2O3, which is known as highly active catalyst, for instance in the oxidation of CO. The sample was characterised by using X-ray absorption spectroscopy (XAS) in terms of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), Mössbauer spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). These analyses evidenced high dispersion of the iron oxide entities without significant presence of bulk-like aggregates associated with the low Fe content of the catalyst. A library of structural models of Al2O3-supported surface Fe was created as input for EXAFS fitting. Additionally, several model structures of Fe substituting Al ions in bulk γ-Al2O3 were created with optimised geometry based on density-functional theory (DFT) calculations. From EXAFS refinement of the best 8 out of 24 models, it was found that the trivalent Fe ions are coordinated by 4-5 oxygen atoms and are located on octahedral lattice sites of the exposed surfaces of γ-Al2O3. These iron oxide species exist mainly as a mixture of monomeric and binuclear species and due to the low concentration represent suitable model systems as alternative to single crystal systems for structure-function relationships.

  6. Molecular analysis of long-term biofilm formation on PVC and cast iron surfaces in drinking water distribution system.

    Science.gov (United States)

    Liu, Ruyin; Zhu, Junge; Yu, Zhisheng; Joshi, DevRaj; Zhang, Hongxun; Lin, Wenfang; Yang, Min

    2014-04-01

    To understand the impacts of different plumbing materials on long-term biofilm formation in water supply system, we analyzed microbial community compositions in the bulk water and biofilms on faucets with two different materials-polyvinyl chloride (PVC) and cast iron, which have been frequently used for more than10 years. Pyrosequencing was employed to describe both bacterial and eukaryotic microbial compositions. Bacterial communities in the bulk water and biofilm samples were significantly different from each other. Specific bacterial populations colonized on the surface of different materials. Hyphomicrobia and corrosion associated bacteria, such as Acidithiobacillus spp., Aquabacterium spp., Limnobacter thiooxidans, and Thiocapsa spp., were the most dominant bacteria identified in the PVC and cast iron biofilms, respectively, suggesting that bacterial colonization on the material surfaces was selective. Mycobacteria and Legionella spp. were common potential pathogenic bacteria occurred in the biofilm samples, but their abundance was different in the two biofilm bacterial communities. In contrast, the biofilm samples showed more similar eukaryotic communities than the bulk water. Notably, potential pathogenic fungi, i.e., Aspergillus spp. and Candida parapsilosis, occurred in similar abundance in both biofilms. These results indicated that microbial community, especially bacterial composition was remarkably affected by the different pipe materials (PVC and cast iron).

  7. Anomalous magnetic Properties of an iron film System deposited on fracture surfaces of α-Al2O3 ceramics

    Institute of Scientific and Technical Information of China (English)

    Jiao Zhi-Wei; Chen Miao-Gen; Jiang Wei-Di; Feng Chun-Mu; Ye Gao-Xiang

    2008-01-01

    An iron film percolation system is fabricated by vapour-phase deposition on fracture surfaces of α-Al2O3 ceramics.The zero-field-cooled(ZFC)and field-cooled(FC)magnetization measurement reveals that the magnetic phase of the film samples evolve from a high-temperature ferromagnetic state to a low-temperature spin-glass-fike state.which is also demonstrated by the temperature-dependent ac susceptibility of the iron films.The temperature dependence of the exchange bias field He of the iron film exhibits a minimum peak around the temperature T=5 K,which is independent of the magnitude of the cooling field Hcf.However,for T>10 K,(1)He is always negative when Hcf=2 kOe and(2) for Hcf=20kOe(1Oe≈80A/m),He changes from negative to positive values as T increases.Our experimental results show that the anomalous hysteresis properties mainly result from the oxide surfaces of the films with spin-glass-like phase.

  8. Melting of iron determined by X-ray absorption spectroscopy to 100 GPa.

    Science.gov (United States)

    Aquilanti, Giuliana; Trapananti, Angela; Karandikar, Amol; Kantor, Innokenty; Marini, Carlo; Mathon, Olivier; Pascarelli, Sakura; Boehler, Reinhard

    2015-09-29

    Temperature, thermal history, and dynamics of Earth rely critically on the knowledge of the melting temperature of iron at the pressure conditions of the inner core boundary (ICB) where the geotherm crosses the melting curve. The literature on this subject is overwhelming, and no consensus has been reached, with a very large disagreement of the order of 2,000 K for the ICB temperature. Here we report new data on the melting temperature of iron in a laser-heated diamond anvil cell to 103 GPa obtained by X-ray absorption spectroscopy, a technique rarely used at such conditions. The modifications of the onset of the absorption spectra are used as a reliable melting criterion regardless of the solid phase from which the solid to liquid transition takes place. Our results show a melting temperature of iron in agreement with most previous studies up to 100 GPa, namely of 3,090 K at 103 GPa.

  9. Determination the Level of Dust ond Free Silica in Air of Khaf Iron Stone Quarries

    Directory of Open Access Journals (Sweden)

    A Dadpour4

    2008-09-01

    Full Text Available Background and Objectives: Silica is an inorganic material that found in the nature in various forms. The hazards of crystal of silica or α-quartz (free silica is greater than other forms. Exposure to dust that contains free silica result to pulmonary injury and result to silicosis and death finally. The present research was conducted in order to evaluate the level of workers exposure to free silica in air of Khaf Iron stone quarries."nMaterials and methods: The exposure level to total and respiratory dust measured based on personal and environmental sampling methods and concentration of dust determined based on gravimetric method. For determination of amounts of free silica, dust samples analyses based on X-ray diffraction (XRD method, and results compared with standard levels."nResults: The maximum amount of total dust and free silica measured in stone breaking station (800±155mg/m3 and 26.11±6.7 mg/m3 and minimum of them measured in official and safeguarding station (8.28±2.2 mg/m3 and 0.012±0.0019 mg/m3. The maximum amount of respiratory dust and free silica measured in red mound digging number 1 (66.14±13.45 mg/m3 and 1.48±0.39 mg/m3 and minimum of them measured in air hammer machine station (5.26±2.62 mg/m3 and 0.01±0.005 mg/m3."nConclusion: Amount of total dust only in official and safeguarding station was lower than standard levels of Iran. Amount of respiratory dust in all stations was greater than Iran standard levels. Furthermore the level of respiratory free silica only in airy hammer machine station was lower than standard level of Iran. Regarding to this amounts it is so essential to that with applying different methods generation and emission of dust protected.

  10. Prebiotic Oxidative Polymerization of 2,3 Dimercaptopropanol on the Surface of Iron(III) Hydroxide Oxide

    Science.gov (United States)

    Weber, Arthur L.

    1994-01-01

    The oxidation of 2,3-Dimercapto-1-propanol by ferric ions on the surface of iron (III) hydroxide oxide yielded polydisulfide polymers. This polymerization occured readily at low dithiol concentration under mild aqueous conditions. Polydisulfide polymers up to the 15-mer were synthesized from 1 mM dithiol in 5 ml water reacted with iron (III) hydroxide oxide (20 mg, 160 micro mole Fe) for 3 days under anaerobic conditions at 40 C and pH 4. About 91% of the dithiol was converted to short soluble oligomers and 9% to insoluble larger oligomers that were isolated with the mineral phase. Reactions at higher dithiol concentrations with the same ratio of dithiol to mineral gave a higher yield of the larger insoluble oligomers. The relationship of these results to prebiotic polymer synthesis will be discussed.

  11. Prebiotic Polymerization: Oxidative Polymerization of 2,3 Dimercapto-1- Propanol on the Surface of Iron(III) Hydroxide Oxide

    Science.gov (United States)

    Weber, Arthur L.

    1995-01-01

    The oxidation of 2,3-dimercapto-1-propanol by ferric ions on the surface of iron(III) hydroxide oxide (Fe(OH)O) yielded polydisulfide oligomers. This polymerization occurred readily at low dithiol concentration under mild aqueous conditions. Polydisulfide polymers up to the 15-mer were synthesized from 1 mM dithiol in 5 ml water reacted with iron(III) hydroxide oxide (20 mg, 160 micromole Fe) for 3 days under anaerobic conditions at 40 C and pH 4. About 91% of the dithiol was converted to short soluble oligomers and 9% to insoluble larger oligomers that were isolated with the FE(OH)O phase. Reactions carried out at the same ratio of dithiol to FE(OH)O but at higher dithiol concentrations gave higher yields of the larger insoluble oligomers. The relationship of these results to prebiotic polymer synthesis is discussed.

  12. Prebiotic polymerization: Oxidative polymerization of 2, 3-dimercapto-1-propanol on the surface of iron(III) hydroxide oxide

    Science.gov (United States)

    Weber, Arthur L.

    1995-01-01

    The oxidation of 2, 3-dimercapto-1-propanol by ferric ions on the surface of iron(III) hydroxide oxide (Fe(OH)O) yielded polydisulfide oligomers. This polymerization occurred readily at low dithiol concentration under mild aqueous conditions. Polydisulfide polymers up to the 15-mer were synthesized from 1 mM dithiol in 5 ml water reacted with iron(III) hydroxide oxide (20 mg, 160 micromole Fe) for 3 days under anaerobic conditions at 40 C and pH 4. About 91% of the dithiol was converted to short soluble oligomers and 9% to insoluble larger oligomers that were isolated with the Fe(OH)O phase. Reactions carried out at the same ratio of dithiol to Fe(OH)O but at higher dithiol concentrations gave higher yields of the larger insoluble oligomers. The relationship of these results to prebiotic polymer synthesis is discussed.

  13. Corrosion inhibition of Eleusine aegyptiaca and Croton rottleri leaf extracts on cast iron surface in 1 M HCl medium

    Science.gov (United States)

    Rajeswari, Velayutham; Kesavan, Devarayan; Gopiraman, Mayakrishnan; Viswanathamurthi, Periasamy; Poonkuzhali, Kaliyaperumal; Palvannan, Thayumanavan

    2014-09-01

    The adsorption and corrosion inhibition activities of Eleusine aegyptiaca (E. aegyptiaca) and Croton rottleri (C. rottleri) leaf extracts on cast iron corrosion in 1 M hydrochloric acid solution were studied first time by weight loss and electrochemical techniques viz., Tafel polarization and electrochemical impedance spectroscopy. The results obtained from the weight loss and electrochemical methods showed that the inhibition efficiency increased with inhibitor concentrations. It was found that the extracts acted as mixed-type inhibitors. The addition of halide additives (KCl, KBr, and KI) on the inhibition efficiency has also been investigated. The adsorption of the inhibitors on cast iron surface both in the presence and absence of halides follows the Langmuir adsorption isotherm model. The inhibiting nature of the inhibitors was supported by FT-IR, UV-vis, Wide-angle X-ray diffraction and SEM methods.

  14. Determination of Glacier Surface Area Using Spaceborne SAR Imagery

    Science.gov (United States)

    Fang, L.; Maksymiuk, O.; Schmitt, M.; Stilla, U.

    2013-04-01

    Glaciers are very important climate indicators. Although visible remote sensing techniques can be used to extract glacier variations effectively and accurately, the necessary data are depending on good weather conditions. In this paper, a method for determination of glacier surface area using multi-temporal and multi-angle high resolution TerraSAR-X data sets is presented. We reduce the "data holes" in the SAR scenes affected by radar shadowing and specular backscattering of smooth ice surfaces by combining the two complementary different imaging geometries (from ascending and descending satellite tracks). Then, a set of suitable features is derived from the intensity image, the texture information generated based on the gray level co-occurrence matrix (GLCM), glacier velocity estimated by speckle tracking, and the interferometric coherence map. Furthermore, the features are selected by 10-foldcross- validation based on the feature relevance importance on classification accuracy using a Random Forests (RF) classifier. With these most relevant features, the glacier surface is discriminated from the background by RF classification in order to calculate the corresponding surface area.

  15. High speed CO2 laser surface modification of iron/cobalt co-doped boroaluminosilicate glass and the impact on surface roughness, gloss and wettability

    Science.gov (United States)

    Hodgson, S. D.; Waugh, D. G.; Gillett, A.; Lawrence, J.

    2016-07-01

    A preliminary study into the impact of high speed laser processing on the surface of iron and cobalt co-doped glass substrates using a 60 W continuous wave (cw) CO2 laser. Two types of processing, termed fill-processing and line-processing, were trialled. In fill-processed samples the surface roughness of the glass was found to increase linearly with laser power from an S a value of 20.8 nm-2.1 μm at a processing power of 54 W. With line processing, a more exponential-like increase was observed with a roughness of 4 μm at 54 W. The change in surface properties of the glass, such as gloss and wettability, have also been measured. The contact angle of water was found to increase after laser processing by up to 64°. The surface gloss was varied between 45 and 100 gloss units (GUs).

  16. Identification and determination of the contribution of iron-steel manufacturing industry to sediment-associated polycyclic aromatic hydrocarbons (PAHs) in a large shallow lake of eastern China.

    Science.gov (United States)

    Zhang, Liu; Bai, Ya-Shu; Wang, Ji-Zhong; Peng, Shu-Chuan; Chen, Tian-Hu; Yin, Da-Qiang

    2016-11-01

    Seventeen polycyclic aromatic hydrocarbon (PAH) compounds were determined in surface sediments collected from the Chaohu Lake (a large shallow lake in eastern China) and its tributaries. Both diagnostic ratios and a receptor model (positive matrix factorization, PMF) were applied to identify and determine the contribution of a local iron-steel manufacturing plant located in the Nanfei River (NFR) to the Chaohu Lake basin. The results show that sites located in the downstream of the steel plant contained concentrations of 17 PAH (Σ17PAH) approximately two orders of magnitudes higher than those from other sites. Five factors were identified by the PMF model, including industrial waste, wood/biomass burning, diagenetic origin, domestic coal combustion, and industrial combustion. Our findings suggest that sediments in the downstream of the plant and in the western part of the Chaohu Lake were predominantly affected by industrial coal combustion. A mixture of pyrolytic origins impacted urban sediments in the upstream of the plant, whereas diagenetic origins along with coal and biomass burning were suggested to influence the eastern part and rural tributaries of the lake. To assess the potential ecological risk and toxicity caused by the iron-steel plant, sediment toxicity was evaluated by the PMF model, sediment quality guideline, and toxic equivalent factors. All of the three approaches suggested PAH accumulation in the NFR sediments could produce significant adverse ecological effects and half of the sediment toxicity in the NFR may be attributed to the emissions from the iron-steel plant. Some rural locations also exhibited PAH concentrations above probable effects, most likely contributed by wood/biomass burning.

  17. Potential ecological and human health risks of heavy metals in surface soils associated with iron ore mining in Pahang, Malaysia.

    Science.gov (United States)

    Diami, Siti Merryan; Kusin, Faradiella Mohd; Madzin, Zafira

    2016-10-01

    The composition of heavy metals (and metalloid) in surface soils of iron ore mine-impacted areas has been evaluated of their potential ecological and human health risks. The mining areas included seven selected locations in the vicinity of active and abandoned iron ore-mining sites in Pahang, Malaysia. Heavy metals such as Fe, Mn, Cu, Zn, Co, Pb, Cr, Ni, and Cd and metalloid As were present in the mining soils of the studied area, while Cu was found exceeding the soil guideline value at all sampling locations. However, the assessment of the potential ecological risk index (RI) indicated low ecological risk (RI between 44 and 128) with respect to Cd, Pb, Cu, As, Zn, Co, and Ni in the surface soils. Contributions of potential ecological risk [Formula: see text]by metal elements to the total potential ecological RI were evident for Cd, As, Pb, and Cu. Contribution of Cu appears to be consistently greater in the abandoned mining area compared to active iron ore-mining site. For non-carcinogenic risk, no significant potential health risk was found to both children and adults as the hazard indices (HIs) were all below than 1. The lifetime cancer risk (LCR) indicated that As has greater potential carcinogenic risk compared to other metals that may induce carcinogenic effects such as Pb, Cr, and Cd, while the LCR of As for children fell within tolerable range for regulatory purposes. Irrespective of carcinogenic or non-carcinogenic risk, greater potential health risk was found among children (by an order of magnitude higher for most metals) compared to adults. The hazard quotient (HQ) and cancer risk indicated that the pathways for the risk to occur were found to be in the order of ingestion > dermal > inhalation. Overall, findings showed that some metals and metalloid were still present at comparable concentrations even long after cessation of the iron ore-mining activities.

  18. Direct determination of surface albedos from satellite imagery

    Science.gov (United States)

    Mekler, Y.; Joseph, J. H.

    1983-01-01

    An empirical method to measure the spectral surface albedo of surfaces from Landsat imagery is presented and analyzed. The empiricism in the method is due only to the fact that three parameters of the solution must be determined for each spectral photograph of an image on the basis of independently known albedos at three points. The approach is otherwise based on exact solutions of the radiative transfer equation for upwelling intensity. Application of the method allows the routine construction of spectral albedo maps from satelite imagery, without requiring detailed knowledge of the atmospheric aerosol content, as long as the optical depth is less than 0.75, and of the calibration of the satellite sensor.

  19. Determination of Geopotential of Local Vertical Datum Surface

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This paper first develops the approaches to determine the geopotential of the local mean sea level,and then investigates the offset of the 1985 vertical datum surface defined by the mean sea level of Yellow Sea at the Dagang Tide Gauge in Qingdao city using the developed approaches and GPS/leveling data.It shows that the geopotential of the local mean sea level at the tide gauge is equal to 62 636 853.5±0.2 m2*s-2 and that the 1985 vertical datum surface is 24.6±5.4 cm above the geoid realized by the geopotential W0=62 636 856.0±0.5 m2*s-2.

  20. Factor H-related proteins determine complement-activating surfaces.

    Science.gov (United States)

    Józsi, Mihály; Tortajada, Agustin; Uzonyi, Barbara; Goicoechea de Jorge, Elena; Rodríguez de Córdoba, Santiago

    2015-06-01

    Complement factor H-related proteins (FHRs) are strongly associated with different diseases involving complement dysregulation, which suggests a major role for these proteins regulating complement activation. Because FHRs are evolutionarily and structurally related to complement inhibitor factor H (FH), the initial assumption was that the FHRs are also negative complement regulators. Whereas weak complement inhibiting activities were originally reported for these molecules, recent developments indicate that FHRs may enhance complement activation, with important implications for the role of these proteins in health and disease. We review these findings here, and propose that FHRs represent a complex set of surface recognition molecules that, by competing with FH, provide improved discrimination of self and non-self surfaces and play a central role in determining appropriate activation of the complement pathway.

  1. Optimization of High-Gravity Chelated Iron Process for Removing H2S Based on Response Surface Methodology

    Institute of Scientific and Technical Information of China (English)

    Luo Ying; Zhang Zhongzhe; Qi Jibing; Li Gang; Qi Guisheng; Liu Youzhi

    2015-01-01

    By using a mixture of N2 and H2S as the simulated APG (associated petroleum gas), the desulfurization experi-ment was performed in a cross-lfow rotating packed bed (RPB) based on the chelated iron oxidation-reduction method. In order to determine the operating conditions of the system, the effects of the concentration of Fe3+ions (ranging from 0.1 to 0.2 mol/L), the liquid-gas volume ratio (ranging from 15 to 25 L/m3) and the high gravity factor (ranging from 36 to 126) on the removal of H2S were studied by means of the Box-Behnken design (BBD) under response surface methodology (RSM). The overall results have demonstrated that the BBD with an experimental design can be used effectively in the optimization of the desulfurization process. The optimal conditions based on both individualized and combined responses (at a Fe3+ion concentration of 0.16 mol/L, a liquid-gas volume ratio of 20.67 L/m3 and a high gravity factor of 87) were found. Under this optimum condition, the desulfurization efifciency could reach 98.81%when the H2S concentration was 7 g/m3 in APG. In this work, the sulfur product was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the energy dispersive X-ray spectrometer (EDX). The results of analysis show that the sulfur is made of the high-purity orthorhombic crystals, which are advantageous to environmental conservation.

  2. Structural stability and electronic structure of iron adsorption on the GaN(0 0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Hernandez, Rafael, E-mail: rhernandezj@uninorte.edu.co [GFMC - Grupo de Fisica de la Materia Condensada, Departamento de Fisica, Universidad del Norte, Barranquilla (Colombia); GEMA - Grupo de Estudio de Materiales, Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia); Perez, William Lopez [GFMC - Grupo de Fisica de la Materia Condensada, Departamento de Fisica, Universidad del Norte, Barranquilla (Colombia); Arbey Rodriguez M, Jairo [GEMA - Grupo de Estudio de Materiales, Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia)

    2011-05-01

    In this work, we have investigated by means of first-principles spin-polarized calculations, the electronic and magnetic properties of iron (Fe) adsorption and diffusion on the GaN(0 0 0 1) surface using density functional theory (DFT) within a plane-wave pseudopotential scheme. In the surface adsorption study, results show that the most stable positions of a Fe adatom on GaN(0 0 0 1) surface are the H3 sites and T4 sites, for low and high Fe coverage respectively. We found that the Fe-H3 2 x 2 surface reconstruction exhibits a half-metallic behavior with a spin band gap and stable ferromagnetism ordering, which is a desirable property for high-efficiency magnetoelectronic devices. In addition, confirming previous experimental results, we found that the iron monolayers present a ferromagnetic order and a large thermal stability. This is interesting from a theoretical point of view and for its technological applications.

  3. Corrosion behaviour and structure of the surface layer formed on austempered ductile iron in concentrated sulphuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Krawiec, H. [AGH University of Science and Technology, Department of Foundry Engineering, ul. Reymonta 23, 30-059 Cracow (Poland)]. E-mail: krawiec@uci.agh.edu.pl; Stypula, B. [AGH University of Science and Technology, Department of Foundry Engineering, ul. Reymonta 23, 30-059 Cracow (Poland); Stoch, J. [Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences (PAS), ul. Niezapominajek 8, 30-239 Cracow (Poland); Mikolajczyk, M. [Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences (PAS), ul. Niezapominajek 8, 30-239 Cracow (Poland)

    2006-03-15

    The aim of this paper is to investigate the structure of the surface layer formed on austempered ductile iron (ADI) after exposure to hot concentrated sulphuric acid at the open circuit potential value (OCP). The results derived from polarization measurements carried out in sulphuric acid at a temperature of 90 deg. C show that anodic dissolution of ADI is divided into three stages (corresponding to three anodic dissolution peaks). The structure of the layer formed on alloys at 90 deg. C at OCP was investigated using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). SEM analysis shows that the main elements of the surface layer are iron, silicon, oxygen, sulphur, and carbon. The binding energy recorded in individual bands indicates that the surface layer includes mainly SiO{sub 2} and FeOOH. The presence of sulphur at the lower oxidation state (S{sup 2-}) indicates that sulphuric acid undergoes reduction during this process. The corrosion resistance of these alloys is connected with the presence of SiO{sub 2} in the surface layer.

  4. A novel surface protein of Trichomonas vaginalis is regulated independently by low iron and contact with vaginal epithelial cells.

    Science.gov (United States)

    Mundodi, V; Kucknoor, A S; Chang, T-H; Alderete, J F

    2006-01-31

    Trichomonosis caused by Trichomonas vaginalis is the number one, non-viral sexually transmitted disease (STD) that affects more than 250 million people worldwide. Immunoglobulin A (IgA) has been implicated in resistance to mucosal infections by pathogens. No reports are available of IgA-reactive proteins and the role, if any, of this class of antibody in the control of this STD. The availability of an IgA monoclonal antibody (mAb) immunoreactive to trichomonads by whole cell (WC)-ELISA prompted us to characterize the IgA-reactive protein of T. vaginalis. An IgA mAb called 6B8 was isolated from a library of mAbs reactive to surface proteins of T. vaginalis. The 6B8 mAb recognized a 44-kDa protein (TV44) by immunoblot analysis, and a full-length cDNA clone encoded a protein of 438 amino acids. Southern analysis revealed the gene (tv44) of T. vaginalis to be single copy. The tv44 gene was down-regulated at both the transcriptional and translational levels in iron-depleted trichomonads as well as in parasites after contact with immortalized MS-74 vaginal epithelial cells (VECs). Immunofluorescence on non-permeabilized organisms confirmed surface localization of TV44, and the intensity of fluorescence was reduced after parasite adherence to VECs. Lastly, an identical protein and gene were present in Tritrichomonas foetus and Trichomonas tenax. This is the first report of a T. vaginalis gene (tv44) encoding a surface protein (TV44) reactive with an IgA mAb, and both gene and protein were conserved in human and bovine trichomonads. Further, TV44 is independently down-regulated in expression and surface placement by iron and contact with VECs. TV44 is another member of T. vaginalis genes that are regulated by at least two independent signaling mechanisms involving iron and contact with VECs.

  5. Superparamagnetic iron oxide coated on the surface of cellulose nanospheres for the rapid removal of textile dye under mild condition

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Yunfeng [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, and College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Qin, Zongyi, E-mail: phqin@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, and College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Liu, Yannan; Cheng, Miao; Qian, Pengfei [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, and College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Wang, Qian, E-mail: drwangqian23@163.com [Department of Orthopaedics, Shanghai First People' s Hospital, Shanghai Jiaotong University, 100 Haining Road, Hongkou District, Shanghai 200080 (China); Zhu, Meifang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, and College of Material Science and Engineering, Donghua University, Shanghai 201620 (China)

    2015-12-01

    Graphical abstract: - Highlights: • Anchoring superparamagnetic iron oxide on the surface of cellulose nanospheres as magnetically recyclable nanocatalys. • Achieving highly efficient Fenton-like reaction on the surface of composite nanospheres for rapid removal of textile dye. • Reaching nearly 98.0% degradation of Navy blue within 5 min under mild condition. - Abstract: Magnetic composite nanoparticles (MNPs) were prepared by anchoring iron oxide (Fe{sub 3}O{sub 4}) on the surface of carboxyl cellulose nanospheres through a facile chemical co-precipitation method. The as-prepared MNPs were characterized by atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray diffraction measurement, thermal gravity analysis and vibrating sample magnetometry. These MNPs were of a generally spherical shape with a narrow size distribution, and exhibited superparamagnetic behaviors with high saturation magnetization. High efficient removal of Navy blue in aqueous solution was demonstrated at room temperature in a Fenton-like system containing the MNPs and H{sub 2}O{sub 2}, which benefited from small particle size, large surface area, high chemical activity, and good dispersibility of the MNPs. The removal efficiency of Navy blue induced by the MNPs prepared at a weight ratio of cellulose to iron of 1:2 were 90.6% at the first minute of the degradation reaction, and 98.0% for 5 min. Furthermore, these MNPs could be efficiently recycled and reused by using an external magnetic field. The approach presented in this paper promotes the use of renewable natural resources as templates for the preparation and stabilization of various inorganic nanomaterials for the purpose of catalysis, magnetic resonance imaging, biomedical and other potential applications.

  6. Influence of iron solubility and charged surface-active compounds on lipid oxidation in fatty acid ethyl esters containing association colloids.

    Science.gov (United States)

    Homma, Rika; Johnson, David R; McClements, D Julian; Decker, Eric A

    2016-05-15

    The impact of iron compounds with different solubilities on lipid oxidation was studied in the presence and absence of association colloids. Iron (III) sulfate only accelerated lipid oxidation in the presence of association colloids while iron (III) oleate accelerated oxidation in the presence and absence of association colloids. Further, iron (III) oxide retarded lipid oxidation both with and without association colloids. The impact of charged association colloids on lipid oxidation in ethyl oleate was also investigated. Association colloids consisting of the anionic surface-active compound dodecyl sulphosuccinate sodium salt (AOT), cationic surface-active compound hexadecyltrimethylammonium bromide (CTAB), and nonionic surface-active compound 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton X-100) retarded, promoted, and had no effect on lipid oxidation rates, respectively. These results indicate that the polarity of metal compounds and the charge of association colloids play a big role in lipid oxidation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Chitosan-iron oxide nanocomposite based electrochemical aptasensor for determination of malathion.

    Science.gov (United States)

    Prabhakar, Nirmal; Thakur, Himkusha; Bharti, Anu; Kaur, Navpreet

    2016-10-05

    An electrochemical aptasensor based on chitosan-iron oxide nanocomposite (CHIT-IO) film deposited on fluorine tin Oxide (FTO) was developed for the detection of malathion. Iron oxide nanoparticles were prepared by co-precipitation method and characterized by Transmission electron microscopy and UV-Visible spectroscopy. The biotinylated DNA aptamer sequence specific to the malathion was immobilized onto the iron oxide doped-chitosan/FTO electrode by using streptavidin as linking molecule. Various characterization studies like Field Emission-Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Electrochemical studies were performed to attest the successful fabrication of bioelectrodes. Experimental parameters like aptamer concentration, response time, stability of electrode and reusability studies were optimized. Aptamer immobilized chitosan-iron oxide nanocomposite (APT/SA/CHIT-IO/FTO) bioelectrodes exhibited LOD of about 0.001 ng/mL within 15 min and spike-in studies revealed about 80-92% recovery of malathion from the lettuce leaves and soil sample. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Determining iron content in Mediterranean soils in partly vegetated areas, using spectral reflectance and imaging spectroscopy

    NARCIS (Netherlands)

    Bartholomeus, H.; Epema, G.F.; Schaepman, M.E.

    2007-01-01

    The possibility of quantifying iron content in the topsoil of the slopes of the El Hacho Mountain complex in Southern Spain using imaging spectroscopy is investigated. Laboratory, field and airborne spectrometer (ROSIS) data are acquired, in combination with soil samples, which are analysed for dith

  9. Determination Of Partial Molar Volumes Of Iron Species In Silicate Melts

    Science.gov (United States)

    Dwyer, C. A.; Kress, V. C.

    2009-12-01

    One of the major questions of planetary geology is the composition and conditions of the Earth interior. Magmas are among our most important windows into the interior. Iron, being a major element with multiple valence states, is an important influence on redox state. One way to investigate redox state is via a volume equation of state. Density data are used in computing partial molar volumes, which may then be used to construct a volume equation of state. We have devised an apparatus which permits high-quality density measurements in silicate melts at high temperatures (up to ≈1500 °C) and reduced oxygen fugacity at atmospheric pressure using the Archimedean single-bob method. With this apparatus, we have collected the first high-quality density data of iron-bearing silicate melts which had their iron predominately as ferrous. We measured the density of Columbia River Basalt (approximate temperature range: 1250 °C -- 1450 °C) and an artificial composition in the FeO-FeO1.5-CaO-SiO2 system (≈1460 °C) at the oxygen fugacity corresponding to the Iron-Wüstite buffer. We used these data in conjunction with literature density data gathered at thermodynamic equilibrium to calculate the partial molar volume of the iron species as a function of temperature at standard pressure. We speciated iron according to: 0.4 FeO + 0.6 FeO1.5 ↔ FeO1.3 The partial molar volumes of FeO, FeO1.5, and FeO1.3 were fit well with no compositional dependence, despite the wide range of compositions included in this study. To the extent that melt structure can be inferred from partial molar volumes, this result suggests that there is no compositional dependency to the structure of any of these iron species. Our partial molar volumes of FeO and FeO1.5 are consistent within one standard error of those found by Lange & Carmichael (1987) and Ghiorso & Kress (2004). However, our partial molar volume for FeO1.3 at reference temperature was one-third that of Ghiorso & Kress (2004) (Lange

  10. Environmental application of millimeter-scale sponge iron (s-Fe{sup 0}) particles (II): The effect of surface copper

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Yongming, E-mail: juyongming@scies.org [South China Institute of Environmental Sciences, The Ministry of Environmental Protection of the PRC, Guangzhou 510655 (China); Liu, Xiaowen, E-mail: liuxiaowen@scies.org [South China Institute of Environmental Sciences, The Ministry of Environmental Protection of the PRC, Guangzhou 510655 (China); Liu, Runlong; Li, Guohua; Wang, Xiaoyan; Yang, Yanyan; Wei, Dongyang; Fang, Jiande [South China Institute of Environmental Sciences, The Ministry of Environmental Protection of the PRC, Guangzhou 510655 (China); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering (DBCEE), University of Cincinnati, Cincinnati, Ohio 45221-0012 (United States)

    2015-04-28

    Highlights: • Facile reduction reaction achieves decoration of Cu{sup 0} onto the surface of s-Fe{sup 0}. • The removal efficiency of RhB over Cu{sup 0}–s-Fe{sup 0} was similar to that of Cu{sup 0}–nZVI. • Cu{sup 0}–s-Fe{sup 0} can operate under mild condition with lower cost compared to nZVI. • The reductive mechanism over Cu{sup 0}–s-Fe{sup 0} under US condition is also elucidated. - Abstract: To enhance the catalytic reactivity of millimeter-scale particles of sponge iron (s-Fe{sup 0}), Cu{sup 2+} ions were deposited on the surface of s-Fe{sup 0} using a simple direct reduction reaction, and the catalytic properties of the bimetallic system was tested for removal of rhodamine B (RhB) from an aqueous solution. The influence of Cu{sup 0} loading, catalyst dosage, particle size, initial RhB concentration, and initial pH were investigated, and the recyclability of the catalyst was also assessed. The results demonstrate that the 3 ∼ 5 millimeter s-Fe{sup 0} particles (s-Fe{sup 0}(3 ∼ 5 mm)) with 5 wt% Cu loading gave the best results. The removal of RhB followed two-step, pseudo-first-order reaction kinetics. Cu{sup 0}–s-Fe{sup 0} showed excellent stability after five reuse cycles. Cu{sup 0}–s-Fe{sup 0} possesses great advantages compared to nanoscale zero-valent iron, iron power, and iron flakes as well as its bimetals. The surface Cu{sup 0} apparently catalyzes the production of reactive hydrogen atoms for indirect reaction and generates Fe-Cu galvanic cells that enhance electron transfer for direct reaction. This bimetallic catalyst shows great potential for the pre-treatment of recalcitrant wastewaters. Additionally, some oxides containing iron element are selected to simulate the adsorption process. The results prove that the adsorption process of FeOOH, Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} played minor role for the removal of RhB.

  11. Determination of total iron in food samples after flow injection preconcentration on polyurethane foam functionalized with N,N-bis(salicylidene)-1,3-propanediamine.

    Science.gov (United States)

    Abdel-Azeem, S M; Bader, N R; Kuss, H M; El-Shahat, M F

    2013-06-01

    A highly selective flow injection sorption system was developed for the fast determination of total iron in food samples. Iron (III) was reduced to iron (II) by ascorbic acid and preconcentrated on a mini-column packed with polyurethane foam (PUF) functionalized with N,N-bis(salicylidene)-1,3-propanediamine (SPDA). The retained Fe (II) was eluted with hydrochloric acid and subsequently reacted to 2,4,6-tri(2'-pyridyl)-1,3,5-triazine (TPTZ) then measured at 593 nm. The procedure has resulted preconcentration factor 36, sample frequency 20 h(-1) and detection limit 18 μg L(-1). The precision (RSD) was found to be 5.7% and 3.1% at concentration levels 0.1 and 5.0 μg mL(-1) iron (II), respectively. Finally, the method was successfully applied to determination of total iron in reference material and food samples.

  12. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  13. A comparison of MRI tissue relaxometry and ROI methods used to determine regional brain iron concentrations in restless legs syndrome

    Directory of Open Access Journals (Sweden)

    Moon HJ

    2015-07-01

    Full Text Available Hye-Jin Moon,1,* Yongmin Chang,2,* Yeong Seon Lee,1 Huijin Song,3 Hyuk Won Chang,4 Jeonghun Ku,5 Richard P Allen,6 Christopher J Earley,6 Yong Won Cho1 1Department of Neurology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Republic of Korea; 2Department of Molecular Medicine, 3Department of Medical and Biological Engineering, Kyungpook National University and Hospital, Daegu, Republic of Korea; 4Department of Radiology, 5Department of Biomedical Engineering, School of Medicine, Keimyung University, Daegu, Republic of Korea; 6Department of Neurology, Johns Hopkins University, Hopkins Bayview Medical Center, Baltimore, MD, USA *These authors contributed equally to this work Purpose: Magnetic resonance imaging relaxometry studies differed on the relaxometry methods and their approaches to determining the regions of interest (ROIs in restless legs syndrome (RLS patients. These differences could account for the variable and inconsistent results found across these studies. The aim of this study was to assess the relationship between the different relaxometry methods and different ROI approaches using each of these methods on a single population of controls and RLS subjects. Methods: A 3.0-T magnetic resonance imaging with the gradient-echo sampling of free induction decay and echo pulse sequence was used. The regional brain “iron concentrations” were determined using three relaxometry metrics (R2, R2*, and R2' through two different ROI methods. The substantia nigra (SN was the primary ROI with red nucleus, caudate, putamen, and globus pallidus as the secondary ROIs. Results: Thirty-seven RLS patients and 40 controls were enrolled. The iron concentration as determined by R2 did not correlate with either of the other two methods, while R2* and R2' showed strong correlations, particularly for the substantia nigra and red nucleus. In the fixed-shape ROI method, the RLS group showed a lower iron index compared to the control

  14. DETERMINATION OF IMPORTANCE EVALUATION FOR THE SURFACE EXPLORATORY STUDIES FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    C.J. Byrne

    2000-07-25

    This DIE applies to the surface facilities component of the Yucca Mountain Site Characterization Project (W) ESF. The ESF complex-including surface and subsurface accommodations--encompasses an area that is approximately six miles wide and nine miles long (approximately 30,000 acres total) (United States Department of Energy [DOE] 1997, p. 9.04). It is located on federally withdrawn lands, near the southwest border of the Nevada Test Site (NTS) in southern Nevada (DOE 1997, p. 9.04). Site characterization activities are conducted within the subsurface ESF to obtain the information necessary to determine whether the Yucca Mountain Site is suitable as a geologic repository for spent nuclear fuel and high-level radioactive waste. Most ESF surface facilities are located within the Conceptual Controlled Area Boundary (CCAB) (DOE 1997, p. 9.04), with the exception of the southeastern most portions of the H-Road and the Water Supply System. Various SBT activities are also conducted throughout the Yucca Mountain region as a part of the overall site-characterization effort. In general, the DIE for SBT Activities (Civilian Radioactive Waste Management System [CRWMS] Management and Operating Contractor [M&O] 1998a) evaluates activities associated with SBT. Potential test-to-test interference and waste isolation impacts associated with SBT activities are also evaluated in CRWMS M&O (1998a).

  15. Determining the surface roughness coefficient by 3D Scanner

    Directory of Open Access Journals (Sweden)

    Karmen Fifer Bizjak

    2010-12-01

    Full Text Available Currently, several test methods can be used in the laboratory to determine the roughness of rock joint surfaces.However, true roughness can be distorted and underestimated by the differences in the sampling interval of themeasurement methods. Thus, these measurement methods produce a dead zone and distorted roughness profiles.In this paper a new rock joint surface roughness measurement method is presented, with the use of a camera-typethree-dimensional (3D scanner as an alternative to current methods. For this study, the surfaces of ten samples oftuff were digitized by means of a 3D scanner, and the results were compared with the corresponding Rock JointCoefficient (JRC values. Up until now such 3D scanner have been mostly used in the automotive industry, whereastheir use for comparison with obtained JRC coefficient values in rock mechanics is presented here for the first time.The proposed new method is a faster, more precise and more accurate than other existing test methods, and is apromising technique for use in this area of study in the future.

  16. Pathways of ferrous iron mineral formation upon sulfidation of lepidocrocite surfaces

    NARCIS (Netherlands)

    Hellige, K.; Pollok, K.; Larese-Casanova, P.; Behrends, T.; Peiffer, S.

    2012-01-01

    The interaction between S(-II) and ferric oxides exerts a major control for the sulphur and iron cycle and in particular for the carbon and electron flow in many aquatic systems. It is regarded to be a key reaction leading ultimately to pyrite formation, the pathways still remaining unresolved. We h

  17. Influence of Cycle Temperature on the Wear Resistance of Vermicular Iron Derivatized with Bionic Surfaces

    Science.gov (United States)

    Sui, Qi; Zhang, Peng; Zhou, Hong; Liu, Yan; Ren, Luquan

    2016-11-01

    Depending on their applications, such as in brake discs, camshafts, etc., the wear behavior of vermicular iron is influenced by the thermal cycling regime. The failure of a working part during its service life is a consequence of both thermal fatigue and wear. Previously, the wear and thermal fatigue resistance properties of vermicular iron were separately investigated by researchers, rather than a study combining these two factors. In the present work, the effect of cycle temperature on the wear resistance of specimens with bionic units processed by laser has been investigated experimentally. The wear behavior pre- and post-thermal cycling has also been investigated, and the influence of different cycle temperatures on the wear resistance is discussed. The results indicate that the thermal cycling regime brought about negative influences with varying degrees, on the material properties, such as the microstructures, micro-hardness, cracks, and oxidation resistance properties. All these factors synergistically reduced the wear resistance of vermicular iron. In particular, the negative influence apparently increased with an increase in cycle temperature. Nevertheless, the post-thermal-cycle wear resistance of the specimens with bionic units was superior to those without bionic units. Hence, the laser bionic process is an effective way to improve the performance of vermicular iron in combined thermal cycling and wear service conditions.

  18. Colorimetric and atomic absorption spectrometric determination of mucolytic drug ambroxol through ion-pair formation with iron and thiocyanate.

    Science.gov (United States)

    Levent, Abdulkadir; Sentürk, Zühre

    2010-09-01

    Colorimetric and atomic absorption spectrometric methods have been developed for the determination of mucolytic drug Ambroxol. These procedures depend upon the reaction of iron(III) metal ion with the drug in the presence of thiocyanate ion to form stable ion-pair complex which extractable chloroform. The red-coloured complex was determined either colorimetrically at 510 nm or by indirect atomic absorption spectrometry (AAS) via the determination of the iron content in the formed complex. The optimum experimental conditions for pH, concentrations of Fe(3+) and SCN(-), shaking time, phase ratio, and the number of extractions were determined. Under the proposed conditions, linearity was obeyed in the concentration ranges 4.1x10(-6) - 5.7x10(-5) M (1.7-23.6 µg mL(-1)) using both methods, with detection limits of 4.6x10(-7) M (0.19 µg mL(-1)) for colorimetry and 1.1x10(-6) M (0.46 µg mL(-1)) for AAS. The proposed methods were applied for the determination of Ambroxol in tablet dosage forms. The results obtained were statistically analyzed and compared with those obtained by applying the high-performance liquid chromatographic method with diode-array detection.

  19. Iron Oxide Nanoparticles Coated with a Phosphorothioate Oligonucleotide and a Cationic Peptide: Exploring Four Different Ways of Surface Functionalization

    Directory of Open Access Journals (Sweden)

    Frédéric Geinguenaud

    2015-09-01

    Full Text Available The superparamagnetic iron oxide nanoparticles (SPIONs have great potential in therapeutic and diagnostic applications. Due to their superparamagnetic behavior, they are used clinically as a Magnetic Resonance Imaging (MRI contrast agent. Iron oxide nanoparticles are also recognized todays as smart drug-delivery systems. However, to increase their specificity, it is essential to functionalize them with a molecule that effectively targets a specific area of the body. Among the molecules that can fulfill this role, peptides are excellent candidates. Oligonucleotides are recognized as potential drugs for various diseases but suffer from poor uptake and intracellular degradation. In this work, we explore four different strategies, based on the electrostatic interactions between the different partners, to functionalize the surface of SPIONs with a phosphorothioate oligonucleotide (ODN and a cationic peptide labeled with a fluorophore. The internalization of the nanoparticles has been evaluated in vitro on RAW 264.7 cells. Among these strategies, the “«one-step assembly»”, i.e., the direct complexation of oligonucleotides and peptides on iron oxide nanoparticles, provides the best way of coating for the internalization of the nanocomplexes.

  20. An investigation of abrasive wear and corrosion behavior of surface repair of gray cast iron by SMAW

    Directory of Open Access Journals (Sweden)

    Alireza Sadeghi

    2017-01-01

    Full Text Available In this work, improving the abrasion–corrosion behavior of gray cast iron used in centrifugal pumps was studied. These pumps are usually made of gray cast iron (BS:1452Gr220 and are repaired by Shielded Metal Arc Welding (SMAW. Three different typical welding electrodes including Ni electrode (DIN8563, Carbon Steel electrode (DIN1913, and Hardening electrode (DIN8555 were used to compare the weldability of the base metal. Microstructural differences for three types of electrodes were studied and forming of different phases was analyzed. Corrosion and abrasion tests were conducted and related to welding conditions. Experimental results showed that using Ni substrate electrode reduce the unwanted phases (martensitic and carbides. Furthermore, in comparison with the base metal, the abrasion behavior of all weldments was improved. It was also determined that the carbon steel electrode has a higher corrosion resistance in zero-resistance ammeter (ZRA test compared to other electrodes.

  1. Morphology and phase structures of CW laser-induced oxide layers on iron surface with evolving reflectivity and colors

    Science.gov (United States)

    Wu, Taotao; Wang, Lijun; Wei, Chenghua; Zhou, Menglian; He, Minbo; Wu, Lixiong

    2016-11-01

    Laser-induced oxidation will change the laser reflectivity and color features of metal surface. Both changes can be theoretically calculated based on the oxidation kinetics and the optical constants of oxides. For the purpose of calculation, the laser-induced oxidation process of pure polycrystalline iron was studied. Samples with various color features were obtained by continuous wave Nd:YAG fiber laser (1.06 μm) irradiation depending on progressive durations in the intensity of 1.90 W/cm2. The real-time reflectivity and temperature were measured with integral sphere and thermocouples. The irradiated surface morphology and phase structures were characterized by microscope, X-ray diffraction and Raman spectrum. It was found that the first formed magnetite made the surface reflectivity decline rapidly and caused the "positive feedback" effect because of molecular absorption. The later formed hematite oscillated the reflectivity by interference effect. The oxide films were thin, orientated and badly crystallized. The oxidation process was influenced by the grain orientation of the metal substrate. These results made the mechanism of laser-induced oxidation of iron clear and provided available experimental data for accurate modeling of the oxidation kinetics.

  2. Immobilization of the iron on the surface of non-woven carbon fiber for use in a microbial fuel cell

    Directory of Open Access Journals (Sweden)

    Nichanan Phansroy

    2016-09-01

    Full Text Available Abstract Iron particles were immobilized onto non-woven carbon fiber via electroplating for use in a microbial fuel cell (MFC. Electroplating was performed under an applied voltage at a current of 0.2 A for 5, 10, and 15 min. The scanning electron microscope (SEM observations show that 5 min was not adequate for the particles to be immobilized, whereas 10 and 15 min of electroplating resulted in an adequate number of particles on the surface. To evaluate the strength of the binding of iron via electroplating on the surface of the fiber, the samples were washed with pure water and observed using an SEM. The 10 min electroplated sample has a larger surface area, which is suitable for the MFC anode, than the 15 min electroplated sample. According to X-ray photoelectron spectroscopy and X-ray diffraction analysis, the peaks corresponded to those of Fe2O3, and the sample dipped into tannic acid shows the peaks of Fe3O4. The amount of biofilm of Shewanella oneidensis MR-1 was evaluated using crystal violet staining, and living bacteria were counted as colony forming units. Electroplated Fe2O3 and Fe3O4 were found to be effective for producing biofilm and immobilizing S. oneidensis MR-1.

  3. Simultaneous determination and speciation analysis of arsenic and chromium in iron supplements used for iron-deficiency anemia treatment by HPLC-ICP-MS.

    Science.gov (United States)

    Araujo-Barbosa, Uenderson; Peña-Vazquez, Elena; Barciela-Alonso, Maria Carmen; Costa Ferreira, Sergio Luis; Pinto Dos Santos, Ana Maria; Bermejo-Barrera, Pilar

    2017-08-01

    This work proposes the use of high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for simultaneous speciation of arsenic and chromium in iron supplements used for the treatment of anemia. The sample preparation procedure recommended for the total determination of arsenic and chromium was established using acid digestion in a microwave assisted oven. For speciation analysis, however, the microwave-assisted extraction procedure involved the use of water as extraction solvent at 90°C for 30min. The chromatographic separation was performed using a mobile phase containing 1.0mM tetrabutylammonium hydroxide (TBAH), 0.7mM ethylenediaminetetraacetic acid (EDTA) and 5% methanol at pH 7.2. Helium was used in the collision cell for elimination of the interferences. Under optimized conditions, the separation and detection of the As(III), As(V), Cr(III) and Cr(VI) species can be performed in 5min, permitting their quantification with the external calibration technique with standards prepared in the mobile phase. The limits of quantification obtained were 0.008, 0.010, 0.5 and 0.14µgg(-1), for As(III), As(V), Cr(III) and Cr(VI), respectively. The accuracy of the method was evaluated and confirmed by addition/recovery tests. The recoveries obtained varied from 81% to 110%. The proposed method was applied to the speciation analysis of arsenic and chromium in commercially available iron supplements acquired in several cities in Brazil and Spain. The content of the species ranged from 0.01 to 1.3µgg(-1) for arsenic, and from 0.4 to 61.2µgg(-1) for chromium. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. A new insight into neutrino energy loss by electron capture of iron group nuclei in magnetars surface

    CERN Document Server

    Liu, Jing-Jing

    2016-01-01

    Based on the relativistic mean-field effective interactions theory, and Lai dong model \\citep{b37, b38, b39}, we discuss the influences of superstrong magnetic fields (SMFs) on electron Fermi energy, nuclear blinding energy, and single-particle level structure in magnetars surface. By using the method of Shell-Model Monte Carlo (SMMC), and the Random Phase Approximation (RPA) theory, we detailed analyze the neutrino energy loss rates(NELRs) by electron capture (EC) for iron group nuclei in SMFs.

  5. Comparing the possibilities of austenite content determination in austempered ductile iron

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2011-07-01

    Full Text Available The article presents various methods for assessment of the austenite volume fraction in Austempered Ductile Iron (ADI. Tests were carried out on two types of ADI, i.e. unalloyed and alloyed with the addition of 0.72%Cu and 0.27%Mo, heat treated under different conditions of isothermal transformation to obtain different austenite volume fractions. The test material was then subjected to metallographic examinations, X-ray diffraction (XRD analysis, an analysis using the author's genuine programme of artificial neural networks, image analysis and magnetic measurements. The results were compared with each other indicating the possibility of a quantitative measurement of austenite and other phases present in cast iron. It was found that different methods of measurement are not fully consistent with each other but show similar results of the austenite content.

  6. Evaluation of MR imaging with T1 and T2* mapping for the determination of hepatic iron overload

    Energy Technology Data Exchange (ETDEWEB)

    Henninger, B.; Kremser, C.; Rauch, S.; Eder, R.; Schocke, M. [Innsbruck Medical University, Department of Radiology, Innsbruck (Austria); Zoller, H.; Finkenstedt, A. [Innsbruck Medical University, Department of Internal Medicine, Innsbruck (Austria); Michaely, H.J. [Medical Faculty Mannheim - Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Mannheim (Germany)

    2012-11-15

    To evaluate MRI using T1 and T2* mapping sequences in patients with suspected hepatic iron overload (HIO). Twenty-five consecutive patients with clinically suspected HIO were retrospectively studied. All underwent MRI and liver biopsy. For the quantification of liver T2* values we used a fat-saturated multi-echo gradient echo sequence with 12 echoes (TR = 200 ms, TE = 0.99 ms + n x 1.41 ms, flip angle 20 ). T1 values were obtained using a fast T1 mapping sequence based on an inversion recovery snapshot FLASH sequence. Parameter maps were analysed using regions of interest. ROC analysis calculated cut-off points at 10.07 ms and 15.47 ms for T2* in the determination of HIO with accuracy 88 %/88 %, sensitivity 84 %/89.5 % and specificity 100 %/83 %. MRI correctly classified 20 patients (80 %). All patients with HIO only had decreased T1 and T2* relaxation times. There was a significant difference in T1 between patients with HIO only and patients with HIO and steatohepatitis (P = 0.018). MRI-based T2* relaxation diagnoses HIO very accurately, even at low iron concentrations. Important additional information may be obtained by the combination of T1 and T2* mapping. It is a rapid, non-invasive, accurate and reproducible technique for validating the evidence of even low hepatic iron concentrations. (orig.)

  7. Determination of blood circulation times of superparamagnetic iron oxide nanoparticles by T2* relaxometry using ultrashort echo time (UTE) MRI.

    Science.gov (United States)

    Scharlach, Constantin; Warmuth, Carsten; Schellenberger, Eyk

    2015-11-01

    Blood circulation is an important determinant of the biodistribution of superparamagnetic iron oxide nanoparticles. Here we present a magnetic resonance imaging (MRI) technique based on the use of ultrafast echo times (UTE) for the noninvasive determination of blood half-lives at high particle concentrations, when conventional pulse sequences fail to produce a useful MR signal. Four differently coated iron oxide nanoparticles were administered intravenously at a dose of 500 μmol Fe/kg bodyweight and UTE images of C57BL/6 mice were acquired on a 1-T ICON scanner (Bruker). T2* relaxometry was done by acquiring UTE images with echo times of 0.1, 0.8 and 1.6 ms. Blood circulation time was then determined by fitting an exponential curve to the time course of the measured relaxation rates. Circulation time was shortest for particles coated with malic acid (t1/2=23 min) and longest for particles coated with tartaric acid (t1/2=63 min). UTE-based T2* relaxometry allows noninvasive determination of blood circulation time and is especially useful when high particle concentrations are present. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. The evaluation of the influence of laser treatment parameters on the type of thermal effects in the surface layer microstructure of gray irons

    Science.gov (United States)

    Paczkowska, Marta

    2016-01-01

    The aim of the presented research was to create a laser heat treatment (LHT) diagram presenting singular modifications such as remelting, alloying, hardening from the solid state, tempering the surface layer of gray iron in individual ranges of laser beam parameters (power density and its interaction time). A synthesis of such different thermal phenomena taking place in gray irons surface layer resulting from LHT was the aim of this analysis. The performed research allowed specifying similar, previously created diagrams concerning different engineering materials in general. The created LHT diagram presents singular modifications in the surface layer of gray iron in individual ranges of laser beam parameters. This diagram allows distinguishing ranges of laser beam parameters that could be useful in selecting the LHT parameters or forecasting their effects in the gray iron surface layer. It has been observed that it is possible to achieve the modification of the surface layer of gray iron by applying values of laser beam power density lower than the values of density presented in previously created diagrams related to the influence of LHT parameters on their effects in the surface layer referring to different groups of engineering materials. The limit of the laser beam density was defined resulting in the modification of the surface layer for interaction time t0.2 s (hardening from the solid state). It is not possible to achieve melting or hardening of the surface layer in gray irons using a laser beam density of less than 10 W mm-2. Hardening is possible only with the interaction time longer than 0.2 s and the power beam density between 10 and 40 W mm-2. Tempering of the surface layer is possible with the density of nearly 10 W mm-2 but only with a relatively long interaction time (i.e. 4 s).

  9. Surface-Correlated Nanophase Iron Metal in Lunar Soils: Petrography and Space Weathering Effects

    Science.gov (United States)

    Keller, Lindsay P.; Wentworth, Susan J.; McKay, David S.

    1998-01-01

    Space weathering is a term used to include all of the processes that act on material exposed at the surface of a planetary or small body. In the case of the Moon, it includes a variety of processes that formed the lunar regolith, caused the maturation of lunar soils, and formed patina on rock surfaces. The processes include micrometeorite impact and reworking, implantation of solar wind and flare particles, radiation damage and chemical effects from solar particles and cosmic rays, interactions with the lunar atmosphere, and sputtering erosion and deposition. Space weathering effects collectively result in a reddened continuum slope, lowered albedo, and attenuated absorption features in reflectance spectra of lunar soils as compared to finely comminuted rocks from the same Apollo sites. Understanding these effects is critical in order to fully integrate the lunar sample collection with remotely sensed data from recent robotic missions (e.g., Lunar Prospector, Clementine, Galileo). Our objective is to determine the origin of space weathering effects in lunar soils through combined electron microscopy and microspectrophotometry techniques applied to individual soil particles from lunar soils. It has been demonstrated that it is the finest size fraction (lunar soils that dominates the optical properties of the bulk soils.

  10. Exploring electrosorption at iron electrode with in situ surface-enhanced infrared absorption spectroscopy.

    Science.gov (United States)

    Huo, Sheng-Juan; Wang, Jin-Yi; Yao, Jian-Lin; Cai, Wen-Bin

    2010-06-15

    Surface-enhanced infrared absorption spectroscopy (SEIRAS) in attenuated total reflection (ATR) configuration has been extended to the Fe electrode/electrolyte interface in neutral and weakly acidic solutions for the first time. The SEIRA-active Fe film electrode was obtained through a potentiostatic electrodeposition of a virtually pinhole-free 40 nm-thick Fe overfilm onto a 60 nm-thick Au underfilm chemically predeposited on the reflecting plane of an ATR Si prism. The infrared absorption for CO adlayer at the Fe film electrode measured with ATR-SEIRAS was enhanced by a factor of larger than 34, as compared to that at a Fe bulk electrode with external infrared absorption spectroscopy in the literature. More importantly, the unipolar band shape enabled the reliable determination of the Stark tuning rates of CO adlayer at Fe electrode. In situ ATR-SEIRAS was also applied to study the electrosorption of a typical corrosion inhibitor benzotriazole (BTAH) on Fe electrode as a function of potential, providing additional spectral information at positive potentials in support of the formation of a polymer-like surface complex Fe(II)(m)(BTA)(n) as the corrosion-resistant layer.

  11. 快速测定营养强化大米和铁锅烹饪食品中的铁含量%Rapid Determination of Iron Content in Rice Fortified and Prepared by Iron Wok

    Institute of Scientific and Technical Information of China (English)

    朱战胜; 张晶; 刘素芳; 张慧; 徐贤; 李爽; 卢中建

    2011-01-01

    Fe2+ binds BPDS to form a complex that can be absorbed at wavelength 535nm, so spectrophotometer was used to determine iron content in food. Iron content in FangXin fortified rice was 47.38 mg/kg. Chinese iron wok greatly enriched food iron element in cooking process and delivered 3.73 mg and 14.19 mg iron for soup water and rice congee for every kilogram of starting mass.Under acidic condition of pH 2, as much as 39-fold more iron was dissolved into soup water and reached up to 144.33 mg for every kilogram of starting water. Therefore, iron fortified or iron wok cooking both can meet the dietary requirement of iron nutrition.%Fe2+和水合红菲绕啉(BPDS)结合形成红色络合物,在波长555nm处有最大吸收,以此原理用分光光度计快速测定了食物中的铁含量.用该法实测某铁强化营养大米中的铁含量为47.58mg/kg;而铁锅烹饪可以极大地丰富汤水和米粥中的铁含量,分别达到5.75mg/kg和1 4.19mg/kg起始重量.在pH为2的酸性汤水中烹饪,铁元素加入食物的含量提高59倍,达到144.55mg/kg起始重量.因此,主食大米经铁营养强化和铁锅烹饪都可以满足人体对铁元素的需求.

  12. Satellite techniques for determining the geopotential of sea surface elevations

    Science.gov (United States)

    Pisacane, V. L.

    1986-01-01

    Spaceborne altimetry with measurement accuracies of a few centimeters which has the potential to determine sea surface elevations necessary to compute accurate three-dimensional geostrophic currents from traditional hydrographic observation is discussed. The limitation in this approach is the uncertainties in knowledge of the global and ocean geopotentials which produce satellite and height uncertainties about an order of magnitude larger than the goal of about 10 cm. The quantitative effects of geopotential uncertainties on processing altimetry data are described. Potential near term improvements, not requiring additional spacecraft, are discussed. Even though there is substantial improvements at the longer wavelengths, the oceanographic goal will be achieved. The geopotential research mission (GRM) is described which should produce geopotential models that are capable of defining the ocean geoid to 10 cm and near-earth satellite position. The state of the art and the potential of spaceborne gravimetry is described as an alternative approach to improve our knowledge of the geopotential.

  13. Influence of the shape and surface oxidation in the magnetization reversal of thin iron nanowires grown by focused electron beam induced deposition

    Directory of Open Access Journals (Sweden)

    Luis A. Rodríguez

    2015-06-01

    Full Text Available Iron nanostructures grown by focused electron beam induced deposition (FEBID are promising for applications in magnetic sensing, storage and logic. Such applications require a precise design and determination of the coercive field (HC, which depends on the shape of the nanostructure. In the present work, we have used the Fe2(CO9 precursor to grow iron nanowires by FEBID in the thickness range from 10 to 45 nm and width range from 50 to 500 nm. These nanowires exhibit an Fe content between 80 and 85%, thus giving a high ferromagnetic signal. Magneto-optical Kerr characterization indicates that HC decreases for increasing thickness and width, providing a route to control the magnetization reversal field through the modification of the nanowire dimensions. Transmission electron microscopy experiments indicate that these wires have a bell-type shape with a surface oxide layer of about 5 nm. Such features are decisive in the actual value of HC as micromagnetic simulations demonstrate. These results will help to make appropriate designs of magnetic nanowires grown by FEBID.

  14. Novel genetic algorithm search procedure for LEED surface structure determination.

    Science.gov (United States)

    Viana, M L; dos Reis, D D; Soares, E A; Van Hove, M A; Moritz, W; de Carvalho, V E

    2014-06-04

    Low Energy Electron Diffraction (LEED) is one of the most powerful experimental techniques for surface structure analysis but until now only a trial-and-error approach has been successful. So far, fitting procedures developed to optimize structural and nonstructural parameters-by minimization of the R-factor-have had a fairly small convergence radius, suitable only for local optimization. However, the identification of the global minimum among the several local minima is essential for complex surface structures. Global optimization methods have been applied to LEED structure determination, but they still require starting from structures that are relatively close to the correct one, in order to find the final structure. For complex systems, the number of trial structures and the resulting computation time increase so rapidly that the task of finding the correct model becomes impractical using the present methodologies. In this work we propose a new search method, based on Genetic Algorithms, which is able to determine the correct structural model starting from completely random structures. This method-called here NGA-LEED for Novel Genetic Algorithm for LEED-utilizes bond lengths and symmetry criteria to select reasonable trial structures before performing LEED calculations. This allows a reduction of the parameter space and, consequently of the calculation time, by several orders of magnitude. A refinement of the parameters by least squares fit of simulated annealing is performed only at some intermediate stages and in the final step. The method was successfully tested for two systems, Ag(1 1 1)(4 × 4)-O and Au(1 1 0)-(1 × 2), both in theory versus theory and in theory versus experiment comparisons. Details of the implementation as well as the results for these two systems are presented.

  15. Sol-gel based optical sensor for determination of Fe (II): a novel probe for iron speciation.

    Science.gov (United States)

    Samadi-Maybodi, Abdolraouf; Rezaei, Vida; Rastegarzadeh, Saadat

    2015-02-05

    A highly selective optical sensor for Fe (II) ions was developed based on entrapment of a sensitive reagent, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), in a silica sol-gel thin film coated on a glass substrate. The thin films fabricated based on tetraethoxysilane (TEOS) as precursor, sol-gel pH∼3, water:alkoxyde ratio of 4:1 and TPTZ concentration of 0.112 mol L(-1). The influence of sol-gel parameters on sensing behavior of the fabricated sensor was also investigated. The fabricated sensor can be used for determination of Fe (II) ion with an outstanding high selectivity over a dynamic range of 5-115 ng mL(-1) and a detection limit of 1.68 ng mL(-1). It also showed reproducible results with relative standard deviation of 3.5% and 1.27% for 10 and 90 ng mL(-1) of Fe (II), respectively, along with a fast response time of ∼120 s. Total iron also was determined after reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent. Then, the concentration of Fe (III) was calculated by subtracting the concentration of Fe (II) from the total iron concentration. Interference studies showed a good selectivity for Fe (II) with trapping TPTZ into sol-gel matrix and appropriately adjusting the structure of doped sol-gel. The sensor was compared with other sensors and was applied to determine iron in different water samples with good results.

  16. Structure and friction of stearic acid and oleic acid films adsorbed on iron oxide surfaces in squalane.

    Science.gov (United States)

    Doig, Michael; Warrens, Chris P; Camp, Philip J

    2014-01-14

    The structure and friction of fatty acid surfactant films adsorbed on iron oxide surfaces lubricated by squalane are examined using large-scale molecular dynamics simulations. The structures of stearic acid and oleic acid films under static and shear conditions, and at various surface coverages, are described in detail, and the effects of unsaturation in the tail group are highlighted. At high surface coverage, the measured properties of stearic acid and oleic acid films are seen to be very similar. At low and intermediate surface coverages, the presence of a double bond, as in oleic acid, is seen to give rise to less penetration of lubricant in to the surfactant film and less layering of the lubricant near to the film. The kinetic friction coefficient is measured as a function of shear rate within the hydrodynamic (high shear rate) lubrication regime. Lubricant penetration and layering are observed to be correlated with friction coefficient. The friction coefficient with oleic acid depends only weakly on surface coverage, while stearic acid admits more lubricant penetration, and its friction coefficient increases significantly with decreasing surface coverage. Connections between film structure and friction are discussed.

  17. The Role of Iron-Bearing Minerals in NO 2 to HONO Conversion on Soil Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kebede, Mulu A.; Bish, David L.; Losovyj, Yaroslav; Engelhard, Mark H.; Raff, Jonathan D.

    2016-08-16

    Nitrous acid (HONO) accumulates in the nocturnal boundary layer where it is an important source of daytime hydroxyl radicals. Although there is clear evidence for the involvement of heterogeneous reactions of NO2 on surfaces as a source of HONO, mechanisms remain poorly understood. We used coated-wall flow tube measurements of NO2 reactivity on environmentally relevant surfaces [Fe (hydr)oxides, clay minerals, and soil from Arizona and the Saharan Desert] and detailed mineralogical characterization of substrates to show that reduction of NO2 by Fe-bearing minerals in soil can be a more important source of HONO than the putative NO2 hydrolysis mechanism. The magnitude of NO2-to-HONO conversion depends on the amount of Fe2+ present in substrates and soil surface acidity. Studies examining the dependence of HONO flux on substrate pH revealed that HONO is formed at soil pH < 5 from the reaction between NO2 and Fe2+(aq) present in thin films of water coating the surface, whereas in the range of pH 5–8 HONO stems from reaction of NO2 with structural iron or surface complexed Fe2+ followed by protonation of nitrite via surface Fe-OH2+ groups. Reduction of NO2 on ubiquitous Fe-bearing minerals in soil may explain HONO accumulation in the nocturnal boundary layer and the enhanced [HONO]/[NO2] ratios observed during dust storms in urban areas.

  18. Colloidally stable surface-modified iron oxide nanoparticles: Preparation, characterization and anti-tumor activity

    Energy Technology Data Exchange (ETDEWEB)

    Macková, Hana [Institute of Macromolecular Chemistry, AS CR, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Horák, Daniel, E-mail: horak@imc.cas.cz [Institute of Macromolecular Chemistry, AS CR, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Donchenko, Georgiy Viktorovich; Andriyaka, Vadim Ivanovich; Palyvoda, Olga Mikhailovna; Chernishov, Vladimir Ivanovich [Palladin Institute of Biochemistry, NASU, 9 Leontovich St., 01601 Kiev (Ukraine); Chekhun, Vasyl Fedorovich; Todor, Igor Nikolaevich [R. E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, NASU, 45 Vasylkivska St., 03022 Kiev (Ukraine); Kuzmenko, Oleksandr Ivanovich [Palladin Institute of Biochemistry, NASU, 9 Leontovich St., 01601 Kiev (Ukraine)

    2015-04-15

    Maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles were obtained by co-precipitation of Fe(II) and Fe(III) chlorides and subsequent oxidation with sodium hypochlorite and coated with poly(N,N-dimethylacrylamide-co-acrylic acid) [P(DMAAm-AA)]. They were characterized by a range of methods including transmission electron microscopy (TEM), elemental analysis, dynamic light scattering (DLS) and zeta potential measurements. The effect of superparamagnetic P(DMAAm-AA)-γ-Fe{sub 2}O{sub 3} nanoparticles on oxidation of blood lipids, glutathione and proteins in blood serum was detected using 2-thiobarbituric acid and the ThioGlo fluorophore. Finally, mice received magnetic nanoparticles administered per os and the antitumor activity of the particles was tested on Lewis lung carcinoma (LLC) in male mice line C57BL/6 as an experimental in vivo metastatic tumor model; the tumor size was measured and the number of metastases in lungs was determined. Surface-modified γ-Fe{sub 2}O{sub 3} nanoparticles showed higher antitumor and antimetastatic activities than commercial CuFe{sub 2}O{sub 4} particles and the conventional antitumor agent cisplatin. - Highlights: • Maghemite nanoparticles were prepared and characterized. • Poly(N,N-dimethylacrylamide-co-acrylic acid) coating was synthetized. • Blood lipid, glutathione and protein peroxidation/oxidation was determined. • Antitumor effect of coated particles on Lewis lung carcinoma in mice was observed.

  19. Effect of compaction pressure and powder grade on the microstructure, hardness and surface topography of steam oxidized sintered iron

    Energy Technology Data Exchange (ETDEWEB)

    Mello, J.D.B. de; Hutchings, I.M. [Univ. of Cambridge (United Kingdom); Binder, R. [Embraco, Joinville, S.C. (Brazil); Klein, A.N. [Labmat, UFSC, Florianopolis, S.C. (Brazil)

    2000-07-01

    Steam oxidation has proved to be an effective process to improve the properties of sintered iron components. The wear processes of such surfaces might be expected to be influenced by the presence of pores, the extent of pore closure and the nature and morphology of the oxide produced. In this paper, the influence of compaction pressure and powder grade on the microstructure, oxide content, hardness and surface topography of steam treated sintered iron is analysed. Specimens prepared from atomised powders in different sizes were compacted using 4 different pressure, sintered and then subjected to a continuous steam treatment. A clear influence of the processing parameters on porosity was highlighted. Low porosity is always associated with high compaction pressure and greater powder size. Decreasing powder size always leads to high hardness. Samples produced with smaller powder size show a continuous decrease in hardness as the compaction pressure increases although for the large powder size there is a slight increase to a constant value of ultimate hardness. For the intermediate grain size a maximum hardness is obtained as the compaction pressure increases. X-ray diffraction shows that the oxide layer is composed of magnetite and haematite. No general correlation was found between topographic features, examined using vertical scanning interferometry, and processing parameters or microstructure. (orig.)

  20. Absorption of Nickel, Chromium, and Iron by the Root Surface of Primary Molars Covered with Stainless Steel Crowns

    Directory of Open Access Journals (Sweden)

    David Keinan

    2010-01-01

    Full Text Available Objective. The purpose of this study was to analyze the absorption of metal ions released from stainless steel crowns by root surface of primary molars. Study Design. Laboratory research: The study included 34 primary molars, exfoliated or extracted during routine dental treatment. 17 molars were covered with stainless-steel crowns for more than two years and compared to 17 intact primary molars. Chemical content of the mesial or distal root surface, 1 mm apically to the crown or the cemento-enamel junction (CEJ, was analyzed. An energy dispersive X-ray spectrometer (EDS was used for chemical analysis. Results. Higher amounts of nickel, chromium, and iron (5-6 times were found in the cementum of molars covered with stainless-steel crowns compared to intact molars. The differences between groups were highly significant (<.001. Significance. Stainless-steel crowns release nickel, chromium, and iron in oral environment, and the ions are absorbed by the primary molars roots. The additional burden of allergenic metals should be reduced if possible.

  1. Magnetic control of electrochemical processes at electrode surface using iron-rich graphene materials with dual functionality

    Science.gov (United States)

    Lim, Chee Shan; Ambrosi, Adriano; Sofer, Zdeněk; Pumera, Martin

    2014-06-01

    Metal-doped graphene hybrid materials demonstrate promising capabilities in catalysis and various sensing applications. There also exists great interest for on-demand control of the selectivity of many electrochemical processes. In this work, an iron-doped thermally reduced graphene oxide (Fe-TRGO) was prepared and used to investigate the possibility of a reproducible, magnetically controlled method to modulate electrochemical reactivities through a scalable method. We made use of the presence of both magnetic and electrocatalytic properties in the Fe-TRGOs to induce attraction and removal of the Fe-TRGO material onto and off the working electrode surfaces magnetically, thereby controlling the electrochemical oxidation and reduction processes. The outstanding electrochemical performance of the Fe-TRGO material was evident, with enhanced current signals and lower peak potentials observed upon magnetic activation. Reversible and reproducible cycles of activation and deactivation were obtained as the peak heights and peak potentials remained relatively consistent with no apparent carryover between every step. Both components of Fe-TRGO play an electrocatalytic role in the electrochemical sensing. In the cases of the oxygen reduction reaction and reduction of cumene hydroperoxide, the iron oxide plays the role of an electrocatalyst, while in the cases of ascorbic acid, the enhanced electroactivity originates from the high surface area of the graphene portion in the Fe-TRGO hybrid material. The feasibility of this magnetically switchable method for on-demand sensing and energy production thus brings about potential developments for future electrochemical applications.

  2. Physicochemical nature of iron oxidation in a damp atmospheric condition

    Institute of Scientific and Technical Information of China (English)

    Tongyan PAN; Yunpinq XI

    2011-01-01

    The surface oxidation patterns of iron or low-carbon steels are critical to their life when serving in typical damp environments.An accurate determination of the oxidation pattern entails tracking the iron atoms oxidized at the iron/steel-moisture interface.Using a quantum chemistry-based force field that is capable of simulating chemical reactions,this paper studies the process of iron oxidation under a typical moist condition. The oxidation of iron surface was found to be highly thermodynamic and dependent on the availability of reactants.A triplex structure was formed at the end of a three-stage oxidation process to reduce the overall oxidation speed.The results from this study shed light on the atomistic mechanism of iron oxidation; therefore can be used to guide the protection of general ferrous-based iron/steel structures.

  3. Diuron degradation in irradiated, heterogeneous iron/oxalate systems: the rate-determining step.

    Science.gov (United States)

    Mazellier, P; Sulzberger, B

    2001-08-15

    The purpose of this study was to examine the various factors that control the kinetics of diuron degradation in irradiated, aerated suspensions containing goethite (alpha-FeOOH) and oxalate, in the following denoted as heterogeneous photo-Fenton systems. In these systems, attack by hydroxyl radicals (HO.) was the only pathway of diuron degradation. Studies were conducted in systems containing initially 80 or 200 mg L(-1) goethite (corresponding to 0.9 or 2.25 mM total iron) and 20, 50, 75, 100, 200, and 400 microM oxalate at 3 heterogeneous photo-Fenton systems.

  4. Environmental application of millimetre-scale sponge iron (s-Fe{sup 0}) particles (III): The effect of surface silver

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Yongming [South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655 (China); South China Subcenter of State Environmental Dioxin Monitoring Center, Guangzhou 510655 (China); Innovative Laboratory for Environmental Functional Materials and Environmental Applications of Microwave Irradiation, Guangzhou 510655 (China); Yu, Yunjiang, E-mail: yuyunjiang@scies.org [South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655 (China); Wang, Xiaoyan [South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655 (China); Innovative Laboratory for Environmental Functional Materials and Environmental Applications of Microwave Irradiation, Guangzhou 510655 (China); Zhang, Sukun [South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655 (China); Liu, Runlong [South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655 (China); Innovative Laboratory for Environmental Functional Materials and Environmental Applications of Microwave Irradiation, Guangzhou 510655 (China); Fu, Jianping; Han, Jinglei; Fang, Jiande [South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655 (China); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering (DBCEE), University of Cincinnati, Cincinnati, OH 45221-0012 (United States)

    2015-12-15

    Highlights: • Direct reductive deposition reaction achieves surfaced decoration of s-Fe{sup 0} particles. • Ag{sup 0}-s-Fe{sup 0} displays similar removal efficiency of PCP as compared to bimetal of nZVI. • Ag{sup 0}-s-Fe{sup 0} can be utilized under mild reaction condition compared to bimetal of nZVI. • The catalytic mechanism over Ag{sup 0}-s-Fe{sup 0} under US condition is elucidated. - Abstract: To enhance the dechlorination reactivity of millimetric sponge iron (s-Fe{sup 0}), a facile one-pot method was used to decorate s-Fe{sup 0} with Ag{sup +} ions under ambient conditions. The results recorded by X-ray diffraction patterns, X-ray photoelectron spectra and high-resolution transmission electron microscopy demonstrated that the growth of Ag{sup 0} was dominated primarily by (1 1 1) plane with a mean length of ∼20 nm. The roles of Ag{sup 0} loading, catalyst dosage, particle size, initial pH and contaminant concentration were assessed during the removal of pentachlorophenol (PCP). Catalyst recyclability was also studied. The results revealed that 3–5 mm s-Fe{sup 0} particles with 5 wt% Ag{sup 0} loading exhibited the best performance with a dose of 3.0 g per 60 mL PCP solution. In addition, the dechlorination of PCP followed two-step, pseudo-first-order reaction kinetics, and Ag{sup 0}-s-Fe{sup 0} was advantageous compared with bimetals of nanoscale zero-valent iron, iron power and iron flakes. The dechlorination mechanism of PCP over Ag{sup 0}-s-Fe{sup 0} was attributed to the surface Ag{sup 0} decoration, which catalyzed the formation of reactive hydrogen atoms for indirect reaction, and the direct electron transfer via Fe–Ag{sup 0} galvanic cells for direct reaction. This suggests that Ag-based bimetals of s-Fe{sup 0} have great potential in the pretreatment of organic halogen compounds in aqueous solution.

  5. Iron deposition in modern and archaeological teeth

    Energy Technology Data Exchange (ETDEWEB)

    Williams, A.-M.M., E-mail: AnneMarie.Williams@utas.edu.au [School of Medicine, Private Bag 34, University of Tasmania, Hobart 7001 (Australia); Siegele, R. [Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)

    2014-09-15

    Iron surface concentrations and profile maps were measured on the enamel of archaeological and modern teeth to determine how iron is deposited in tooth enamel and if it was affected by the post-mortem environment. Teeth from Australian children who died in the second half of the 19th century were compared with contemporary teeth extracted for orthodontic purposes. Surface analysis of the teeth was performed using the 3 MV Van Der Graff Accelerator at The Australian Nuclear Science and Technology Organisation (ANSTO), Sydney, Australia. A small sample of teeth were then cut in the mid sagittal plane and analysed using ANSTO High Energy Heavy Ion Microprobe. Maps and linear profiles were produced showing the distribution of iron across the enamel. Results show that both the levels and distribution of iron in archaeological teeth is quite different to contemporary teeth, raising the suggestion that iron has been significantly altered by the post-mortem environment.

  6. Iron deposition in modern and archaeological teeth

    Science.gov (United States)

    Williams, A.-M. M.; Siegele, R.

    2014-09-01

    Iron surface concentrations and profile maps were measured on the enamel of archaeological and modern teeth to determine how iron is deposited in tooth enamel and if it was affected by the post-mortem environment. Teeth from Australian children who died in the second half of the 19th century were compared with contemporary teeth extracted for orthodontic purposes. Surface analysis of the teeth was performed using the 3 MV Van Der Graff Accelerator at The Australian Nuclear Science and Technology Organisation (ANSTO), Sydney, Australia. A small sample of teeth were then cut in the mid sagittal plane and analysed using ANSTO High Energy Heavy Ion Microprobe. Maps and linear profiles were produced showing the distribution of iron across the enamel. Results show that both the levels and distribution of iron in archaeological teeth is quite different to contemporary teeth, raising the suggestion that iron has been significantly altered by the post-mortem environment.

  7. Investigation of iron(III) reduction and trace metal interferences in the determination of dissolved iron in seawater using flow injection with luminol chemiluminescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Ussher, Simon J. [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Milne, Angela [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320 (United States); Landing, William M. [Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320 (United States); Attiq-ur-Rehman, Kakar [Department of Chemistry, University of Balochistan, Quetta (Pakistan); Seguret, Marie J.M.; Holland, Toby [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Achterberg, Eric P. [National Oceanography Centre, University of Southampton, European Way, Southampton SO14 3ZH (United Kingdom); Nabi, Abdul [Department of Chemistry, University of Balochistan, Quetta (Pakistan); Worsfold, Paul J., E-mail: pworsfold@plymouth.ac.uk [School of Earth, Ocean and Environmental Sciences (SEOES), University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

    2009-10-12

    A detailed investigation into the performance of two flow injection-chemiluminescence (FI-CL) manifolds (with and without a preconcentration column) for the determination of sub-nanomolar dissolved iron (Fe(II) + Fe(III)), following the reduction of Fe(III) by sulphite, in seawater is described. Kinetic experiments were conducted to examine the efficiency of reduction of inorganic Fe(III) with sulphite under different conditions and a rigorous study of the potential interference caused by other transition metals present in seawater was conducted. Using 100 {mu}M concentrations of sulphite a reduction time of 4 h was sufficient to quantitatively reduce Fe(III) in seawater. Under optimal conditions, cobalt(II) and vanadium(IV)/(III) were the major positive interferences and strategies for their removal are reported. Specifically, cobalt(II) was masked by the addition of dimethylglyoxime to the luminol solution and vanadium(IV) was removed by passing the sample through an 8-hydroxyquinoline column in a low pH carrier stream. Manganese(II) also interfered by suppression of the CL response but this was not significant at typical open ocean concentrations.

  8. A novel surface protein of Trichomonas vaginalis is regulated independently by low iron and contact with vaginal epithelial cells

    Science.gov (United States)

    Mundodi, V; Kucknoor, AS; Chang, T-H; Alderete, JF

    2006-01-01

    Background Trichomonosis caused by Trichomonas vaginalis is the number one, non-viral sexually transmitted disease (STD) that affects more than 250 million people worldwide. Immunoglobulin A (IgA) has been implicated in resistance to mucosal infections by pathogens. No reports are available of IgA-reactive proteins and the role, if any, of this class of antibody in the control of this STD. The availability of an IgA monoclonal antibody (mAb) immunoreactive to trichomonads by whole cell (WC)-ELISA prompted us to characterize the IgA-reactive protein of T. vaginalis. Results An IgA mAb called 6B8 was isolated from a library of mAbs reactive to surface proteins of T. vaginalis. The 6B8 mAb recognized a 44-kDa protein (TV44) by immunoblot analysis, and a full-length cDNA clone encoded a protein of 438 amino acids. Southern analysis revealed the gene (tv44) of T. vaginalis to be single copy. The tv44 gene was down-regulated at both the transcriptional and translational levels in iron-depleted trichomonads as well as in parasites after contact with immortalized MS-74 vaginal epithelial cells (VECs). Immunofluorescence on non-permeabilized organisms confirmed surface localization of TV44, and the intensity of fluorescence was reduced after parasite adherence to VECs. Lastly, an identical protein and gene were present in Tritrichomonas foetus and Trichomonas tenax. Conclusion This is the first report of a T. vaginalis gene (tv44) encoding a surface protein (TV44) reactive with an IgA mAb, and both gene and protein were conserved in human and bovine trichomonads. Further, TV44 is independently down-regulated in expression and surface placement by iron and contact with VECs. TV44 is another member of T. vaginalis genes that are regulated by at least two independent signaling mechanisms involving iron and contact with VECs. PMID:16448556

  9. A novel surface protein of Trichomonas vaginalis is regulated independently by low iron and contact with vaginal epithelial cells

    Directory of Open Access Journals (Sweden)

    Chang T-H

    2006-01-01

    Full Text Available Abstract Background Trichomonosis caused by Trichomonas vaginalis is the number one, non-viral sexually transmitted disease (STD that affects more than 250 million people worldwide. Immunoglobulin A (IgA has been implicated in resistance to mucosal infections by pathogens. No reports are available of IgA-reactive proteins and the role, if any, of this class of antibody in the control of this STD. The availability of an IgA monoclonal antibody (mAb immunoreactive to trichomonads by whole cell (WC-ELISA prompted us to characterize the IgA-reactive protein of T. vaginalis. Results An IgA mAb called 6B8 was isolated from a library of mAbs reactive to surface proteins of T. vaginalis. The 6B8 mAb recognized a 44-kDa protein (TV44 by immunoblot analysis, and a full-length cDNA clone encoded a protein of 438 amino acids. Southern analysis revealed the gene (tv44 of T. vaginalis to be single copy. The tv44 gene was down-regulated at both the transcriptional and translational levels in iron-depleted trichomonads as well as in parasites after contact with immortalized MS-74 vaginal epithelial cells (VECs. Immunofluorescence on non-permeabilized organisms confirmed surface localization of TV44, and the intensity of fluorescence was reduced after parasite adherence to VECs. Lastly, an identical protein and gene were present in Tritrichomonas foetus and Trichomonas tenax. Conclusion This is the first report of a T. vaginalis gene (tv44 encoding a surface protein (TV44 reactive with an IgA mAb, and both gene and protein were conserved in human and bovine trichomonads. Further, TV44 is independently down-regulated in expression and surface placement by iron and contact with VECs. TV44 is another member of T. vaginalis genes that are regulated by at least two independent signaling mechanisms involving iron and contact with VECs.

  10. Determination of Iron in Layered Crystal Sodium Disilicate and Sodium Silicate by Flame Atomic Absorption Spectrometry with Boric Acid as a Matrix Modifier

    Institute of Scientific and Technical Information of China (English)

    Zhi Hua WANG; Min CAI; Shu Jun WANG

    2006-01-01

    The effects of matrix silicate and experimental conditions on the determination of iron in flame atomic absorption spectrometry (FAAS) were investigated. It was found that boric acid as a matrix modifier obviously eliminated silicate interference. Under the optimum operating conditions, the determination results of iron in layered crystal sodium disilicate and sodium silicate samples by FAAS were satisfactory. The linear range of calibration curve is 0-10.5 μg.mL-1, the relative standard deviation of method is 1.2%-2.2%, the recovery of added iron is 96.0%-101%, the of iron of the standard curve method, standard addition calibration and colorimetry method was the same, but the first has the merits of rapid sample preparation, reduced contamination risks and fast analysis.

  11. Chelator free gallium-68 radiolabelling of silica coated iron oxide nanorods via surface interactions

    Science.gov (United States)

    Burke, Benjamin P.; Baghdadi, Neazar; Kownacka, Alicja E.; Nigam, Shubhanchi; Clemente, Gonçalo S.; Al-Yassiry, Mustafa M.; Domarkas, Juozas; Lorch, Mark; Pickles, Martin; Gibbs, Peter; Tripier, Raphaël; Cawthorne, Christopher; Archibald, Stephen J.

    2015-09-01

    The commercial availability of combined magnetic resonance imaging (MRI)/positron emission tomography (PET) scanners for clinical use has increased demand for easily prepared agents which offer signal or contrast in both modalities. Herein we describe a new class of silica coated iron-oxide nanorods (NRs) coated with polyethylene glycol (PEG) and/or a tetraazamacrocyclic chelator (DO3A). Studies of the coated NRs validate their composition and confirm their properties as in vivo T2 MRI contrast agents. Radiolabelling studies with the positron emitting radioisotope gallium-68 (t1/2 = 68 min) demonstrate that, in the presence of the silica coating, the macrocyclic chelator was not required for preparation of highly stable radiometal-NR constructs. In vivo PET-CT and MR imaging studies show the expected high liver uptake of gallium-68 radiolabelled nanorods with no significant release of gallium-68 metal ions, validating our innovation to provide a novel simple method for labelling of iron oxide NRs with a radiometal in the absence of a chelating unit that can be used for high sensitivity liver imaging.The commercial availability of combined magnetic resonance imaging (MRI)/positron emission tomography (PET) scanners for clinical use has increased demand for easily prepared agents which offer signal or contrast in both modalities. Herein we describe a new class of silica coated iron-oxide nanorods (NRs) coated with polyethylene glycol (PEG) and/or a tetraazamacrocyclic chelator (DO3A). Studies of the coated NRs validate their composition and confirm their properties as in vivo T2 MRI contrast agents. Radiolabelling studies with the positron emitting radioisotope gallium-68 (t1/2 = 68 min) demonstrate that, in the presence of the silica coating, the macrocyclic chelator was not required for preparation of highly stable radiometal-NR constructs. In vivo PET-CT and MR imaging studies show the expected high liver uptake of gallium-68 radiolabelled nanorods with no

  12. A sonochemical approach to the direct surface functionalization of superparamagnetic iron oxide nanoparticles with (3-aminopropyltriethoxysilane

    Directory of Open Access Journals (Sweden)

    Bashiru Kayode Sodipo

    2014-09-01

    Full Text Available We report a sonochemical method of functionalizing superparamagnetic iron oxide nanoparticles (SPION with (3-aminopropyltriethoxysilane (APTES. Mechanical stirring, localized hot spots and other unique conditions generated by an acoustic cavitation (sonochemical process were found to induce a rapid silanization reaction between SPION and APTES. FTIR, XPS and XRD measurements were used to demonstrate the grafting of APTES on SPION. Compared to what was reported in literature, the results showed that the silanization reaction time was greatly minimized. More importantly, the product displayed superparamagnetic behaviour at room temperature with a more than 20% higher saturation magnetization.

  13. On the accessibility of surface-bound drugs on magnetic nanoparticles. Encapsulation of drugs loaded on modified dextran-coated superparamagnetic iron oxide by β-cyclodextrin.

    Science.gov (United States)

    Sudha, Natesan; Yousuf, Sameena; Israel, Enoch V M V; Paulraj, Mosae Selvakumar; Dhanaraj, Premnath

    2016-05-01

    We report the loading of drugs on aminoethylaminodextran-coated iron oxide nanoparticles, their superparamagnetic behavior, loading of drugs on them, and the β-cyclodextrin-complex formation of the drugs on the surface of the nanoparticles. The magnetic behavior is studied using vibrating sample magnetometry and X-ray photoelectron spectroscopy is used to analyze the elemental composition of drug-loaded nanoparticles. Scanning electron microscopy shows ordered structures of drug-loaded nanoparticles. UV-visible absorption and fluorescence spectroscopy are used to study the binding of the surface-loaded drugs to β-cyclodextrin. All of the drugs form 1:1 host-guest complexes. The iodide ion quenching of fluorescence of free- and iron oxide-attached drugs are compared. The binding strengths of the iron oxide surface-loaded drugs-β-cyclodextrin binding are smaller than those of the free drugs.

  14. Iron oxidation kinetics and phosphorus immobilization at the groundwater-surface water interface

    NARCIS (Netherlands)

    van der Grift, Bas; Rozemeijer, Joachim; Griffioen, Jasper; van der Velde, Ype

    2014-01-01

    Eutrophication of freshwater environments following diffuse nutrient loads is a widely recognized water quality problem in catchments. Fluxes of non-point P sources to surface waters originate from surface runoff and flow from soil water and groundwater into surface water. The availability of P in s

  15. Reducing phosphorus loading of surface water using iron-coated sand

    NARCIS (Netherlands)

    Groenenberg, J.E.; Chardon, W.J.; Koopmans, G.F.

    2013-01-01

    Phosphorus losses from agricultural soils is an important source of P in surface waters leading to surface water quality impairment. In addition to reducing P inputs, mitigation measures are needed to reduce P enrichment of surface waters. Because drainage of agricultural land by pipe drainage is an

  16. Chemical equilibrium modeling of organic acids, pH, aluminum, and iron in Swedish surface waters.

    Science.gov (United States)

    Sjöstedt, Carin S; Gustafsson, Jon Petter; Köhler, Stephan J

    2010-11-15

    A consistent chemical equilibrium model that calculates pH from charge balance constraints and aluminum and iron speciation in the presence of natural organic matter is presented. The model requires input data for total aluminum, iron, organic carbon, fluoride, sulfate, and charge balance ANC. The model is calibrated to pH measurements (n = 322) by adjusting the fraction of active organic matter only, which results in an error of pH prediction on average below 0.2 pH units. The small systematic discrepancy between the analytical results for the monomeric aluminum fractionation and the model results is corrected for separately for two different fractionation techniques (n = 499) and validated on a large number (n = 3419) of geographically widely spread samples all over Sweden. The resulting average error for inorganic monomeric aluminum is around 1 µM. In its present form the model is the first internally consistent modeling approach for Sweden and may now be used as a tool for environmental quality management. Soil gibbsite with a log *Ks of 8.29 at 25°C together with a pH dependent loading function that uses molar Al/C ratios describes the amount of aluminum in solution in the presence of organic matter if the pH is roughly above 6.0.

  17. Structure and properties of ultrathin iron films on Ru(10 overline10) : The formation of metastable surface phases of γ-Fe

    Science.gov (United States)

    Harrison, Kevin; Prince, Robert H.; Lambert, Richard M.

    1988-07-01

    The chemisorption and desorption of Fe at the (10 overline10) surface of Ru has been investigated by LEED, Auger spectroscopy, Δφ and thermal desorption measurements over a substrate temperature range of 300-900 K. The growth mode of the iron deposit was found to be strongly dependent on the temperature. At 300 K up to seven iron monolayers could be grown, these adopting the configuration of the fcc (111) plane of bulk γ-iron. The layers were metastable and heating of such films or deposition at elevated temperatures resulted in nucleation and growth of crystallites. Only a single Fe desorption peak ( Ed≈ 250 kJ mol-1) was observed over the whole coverage regime; this is assigned to the evaporation of iron atoms in contact with the ruthenium substrate, either pre-existing in the first monolayer or supplied from the Fe crystallites.

  18. Iron variation within a granitic pluton as determined by near-infrared reflectance

    Science.gov (United States)

    Baird, A. K.

    1984-01-01

    One-hundred fifty-one previously chemically analyzed samples of tonalite from the Lakeview Mountains pluton, southern California batholith, were analyzed for their iron content using near-infrared spectrophotometry. Compared to the earlier analyses of the same sample set by X-ray fluorescence spectrography, the infrared data have higher analytical variance but clearly define patterns of compositional zonation in the pluton which are closely similar to those patterns obtained from X-ray data; petrogenetic interpretations for the pluton would be the same from either data set. Infrared spectral data can be obtained directly in the field with relatively simple instruments and field measurements can be made to average local heterogeneities that often mask significant plutonic variations.

  19. Stopped-in-loop flow analysis system for successive determination of trace vanadium and iron in drinking water using their catalytic reactions.

    Science.gov (United States)

    Ayala Quezada, Alejandro; Ohara, Keisuke; Ratanawimarnwong, Nuanlaor; Nacapricha, Duangjai; Murakami, Hiroya; Teshima, Norio; Sakai, Tadao

    2015-11-01

    An automated stopped-in-loop flow analysis (SILFA) system is proposed for the successive catalytic determination of vanadium and iron. The determination of vanadium was based on the p-anisidine oxidation by potassium bromate in the presence of Tiron as an activator to form a reddish dye, which has an absorption maximum at 510 nm. The selectivity of the vanadium determination was greatly improved by adding diphosphate as a masking agent of iron. For the iron determination, an iron-catalyzed oxidative reaction of p-anisidine by hydrogen peroxide with 1,10-phenanthroline as an activator to produce a reddish dye (510 nm) was employed. The SILFA system consisted of two peristaltic pumps, two six-port injection valves, a four-port selection valve, a heater device, a spectrophotometric detector and a data acquisition device. One six-port injection valve was used for the isolation of a mixed solution of standard/sample and reagent to promote each catalytic reaction, and another six-port injection valve was used for switching the reagent for vanadium or iron to achieve selective determination of each analyte. The above mentioned four-port selection valve was used to select standard solutions or sample. These three valves and the two peristaltic pumps were controlled by a built-in programmable logic controller in a touchscreen controller. The obtained results showed that the proposed SILFA monitoring system constituted an effective approach for the selective determination of vanadium and iron. The limits of detection, 0.052 and 0.55 µg L(-1), were obtained for vanadium and iron, respectively. The proposed system was successfully applied to drinking water samples without any preconcentration procedures.

  20. New Atomic Data for Trans-Iron Elements and Their Application to Abundance Determinations in Planetary Nebulae

    CERN Document Server

    Sterling, N C; Esteves, D A; Bilodeau, R C; Kilcoyne, A L D; Red, E C; Phaneuf, R A; Alna'Washi, G; Aguilar, A

    2010-01-01

    [Abridged] Investigations of neutron(n)-capture element nucleosynthesis and chemical evolution have largely been based on stellar spectroscopy. However, the recent detection of these elements in several planetary nebulae (PNe) indicates that nebular spectroscopy is a promising new tool for such studies. In PNe, n-capture element abundance determinations reveal details of s-process nucleosynthesis and convective mixing in evolved low-mass stars, as well as the chemical evolution of elements that cannot be detected in stellar spectra. Only one or two ions of a given trans-iron element can typically be detected in individual nebulae. Elemental abundance determinations thus require corrections for the abundances of unobserved ions. Such corrections rely on the availability of atomic data for processes that control the ionization equilibrium of nebulae. Until recently, these data were unknown for virtually all n-capture element ions. For the first five ions of Se, Kr, and Xe -- the three most widely detected n-cap...

  1. Determination of aluminium in molybdenum and tungsten metals, iron, steel and ferrous and non-ferrous alloys with pyrocatechol violet.

    Science.gov (United States)

    Donaldson, E M

    1971-09-01

    A method for determining 0.001-0.10% of aluminium in molybdenum and tungsten metals is described. After sample dissolution, aluminium is separated from the matrix materials by chloroform extraction of its acetylacetone complex, at pH 6.5, from an ammonium acetate-hydrogen peroxide medium, then back-extracted into 12M hydrochloric add. Following separation of most co-extracted elements, except for beryllium and small amounts of chroinium(III) and copper(II), by a combined ammonium pyrrolidincdithiocarbamate-cupfen-on-chlorofonn extraction, aluminium is determined spectrophotometrically with Pyrocatechol Violet at 578 nm. Chromium interferes during colour development but beryllium, in amounts equivalent to the aluminium concentration, does not cause significant error in the results. Interference from copper(II) is eliminated by reduction with ascorbic acid. The proposed method is also applicable to iron, steel, ferrovanadium, and copper-base alloys after preliminary removal of the matrix elements by a mercury cathode separation.

  2. Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

    Science.gov (United States)

    Mikhlin, Yuri; Tomashevich, Yevgeny; Vorobyev, Sergey; Saikova, Svetlana; Romanchenko, Alexander; Félix, Roberto

    2016-11-01

    Hard X-ray photoelectron spectroscopy (HAXPES) using an excitation energy range of 2 keV to 6 keV in combination with Fe K- and S K-edge XANES, measured simultaneously in total electron (TEY) and partial fluorescence yield (PFY) modes, have been applied to study near-surface regions of natural polycrystalline pyrite FeS2 and pyrrhotite Fe1-xS before and after etching treatments in an acidic ferric chloride solution. It was found that the following near-surface regions are formed owing to the preferential release of iron from oxidized metal sulfide lattices: (i) a thin, no more than 1-4 nm in depth, outer layer containing polysulfide species, (ii) a layer exhibiting less pronounced stoichiometry deviations and low, if any, concentrations of polysulfide, the composition and dimensions of which vary for pyrite and pyrrhotite and depend on the chemical treatment, and (iii) an extended almost stoichiometric underlayer yielding modified TEY XANES spectra, probably, due to a higher content of defects. We suggest that the extended layered structure should heavily affect the near-surface electronic properties, and processes involving the surface and interfacial charge transfer.

  3. Microstructure and Wear Behavior of TiC Coating Deposited on Spheroidized Graphite Cast Iron Using Laser Surfacing

    Directory of Open Access Journals (Sweden)

    E. R. I. Mahmoud

    2014-10-01

    Full Text Available Spheroidal graphite cast iron was laser cladded with TiC powder using a YAG fiber laser at powers of 700, 1000, 1500 and 2000 W. The powder was preplaced on the surface of the specimens with 0.5 mm thickness. Sound cladding and fusion zones were observed at 700, 1000 and 1500 W powers. However, at 2000 W, cracking was observed in the fusion zone. At 700 W, a build-up zone consisted of fine TiC dendrites inside a matrix composed of martensite, cementite (Fe3C, and some blocks of retained austenite was observed. In this zone, all graphite nodules were totally melted. In the fusion zone, some undissolved and partially dissolved graphite nodules appeared in a matrix containing bainite, ferrite, martensite and retained austenite. At 1500 W, the fusion zone had more iron carbides and ferrite, and the HAZ consisted of martensitic structure. At 2000 W, the build-up zone was consisted of TiC particles precipitated in a matrix of eutectic carbides, martensite plus an inter-lamellar retained austenite. The hardness of the cladded area was remarkably improved (1330 HV in case of 700 W: 5.5 times of the hardness of substrate

  4. Orientation dependences of surface morphologies and energies of iron-gallium alloys

    Science.gov (United States)

    Costa, Marcio; Wang, Hui; Hu, Jun; Wu, Ruqian; Na, Suok-Min; Chun, Hyunsuk; Flatau, Alison B.

    2016-05-01

    We investigated the surface energies of several low-index surfaces of the D03-type FeGa alloys (Galfenol), using density functional theory (DFT) simulations and contact angle measurements. DFT calculations predict that (1) the Ga-covered (110) surface of Galfenol is more stable in the Ga-rich condition, while Ga-covered (001) surface of Galfenol become more favorable in Ga-poor condition; and (2) a full Ga overlayer tends to form on top of Galfenol surfaces regardless their orientation, both in agreement with the experimental observation. We also studied Ga segregation in the bcc Fe matrix in order to explore the possibility of Ga precipitation away from Fe. It was found that the Fe-Ga separation is unlikely to occur since Ga diffusion toward the surface is effectively self-stopped once the Ga overlayers form on the facets.

  5. Analysis of the global ocean sampling (GOS project for trends in iron uptake by surface ocean microbes.

    Directory of Open Access Journals (Sweden)

    Eve Toulza

    Full Text Available Microbial metagenomes are DNA samples of the most abundant, and therefore most successful organisms at the sampling time and location for a given cell size range. The study of microbial communities via their DNA content has revolutionized our understanding of microbial ecology and evolution. Iron availability is a critical resource that limits microbial communities' growth in many oceanic areas. Here, we built a database of 2319 sequences, corresponding to 140 gene families of iron metabolism with a large phylogenetic spread, to explore the microbial strategies of iron acquisition in the ocean's bacterial community. We estimate iron metabolism strategies from metagenome gene content and investigate whether their prevalence varies with dissolved iron concentrations obtained from a biogeochemical model. We show significant quantitative and qualitative variations in iron metabolism pathways, with a higher proportion of iron metabolism genes in low iron environments. We found a striking difference between coastal and open ocean sites regarding Fe(2+ versus Fe(3+ uptake gene prevalence. We also show that non-specific siderophore uptake increases in low iron open ocean environments, suggesting bacteria may acquire iron from natural siderophore-like organic complexes. Despite the lack of knowledge of iron uptake mechanisms in most marine microorganisms, our approach provides insights into how the iron metabolic pathways of microbial communities may vary with seawater iron concentrations.

  6. Inhibition of nitrate reduction by NaCl adsorption on a nano-zero-valent iron surface during a concentrate treatment for water reuse.

    Science.gov (United States)

    Hwang, Yuhoon; Kim, Dogun; Shin, Hang-Sik

    2015-01-01

    Nanoscale zero-valent iron (NZVI) has been considered as a possible material to treat water and wastewater. However, it is necessary to verify the effect of the matrix components in different types of target water. In this study, different effects depending on the sodium chloride (NaCl) concentration on reductions of nitrates and on the characteristics of NZVI were investigated. Although NaCl is known as a promoter of iron corrosion, a high concentration of NaCl (>3 g/L) has a significant inhibition effect on the degree of NZVI reactivity towards nitrate. The experimental results were interpreted by a Langmuir-Hinshelwood-Hougen-Watson reaction in terms of inhibition, and the decreased NZVI reactivity could be explained by the increase in the inhibition constant. As a result of a chloride concentration analysis, it was verified that 7.7-26.5% of chloride was adsorbed onto the surface of NZVI. Moreover, the change of the iron corrosion product under different NaCl concentrations was investigated by a surface analysis of spent NZVI. Magnetite was the main product, with a low NaCl concentration (0.5 g/L), whereas amorphous iron hydroxide was observed at a high concentration (12 g/L). Though the surface was changed to permeable iron hydroxide, the Fe(0) in the core was not completely oxidized. Therefore, the inhibition effect of NaCl could be explained as the competitive adsorption of chloride and nitrate.

  7. Formation of coatings from a liquid phase on the surface of iron-base alloys

    Directory of Open Access Journals (Sweden)

    A. Tatarek

    2008-12-01

    Full Text Available The study discloses the present state of the art regarding the technology and investigations of the phenomena that take place during the formation and growth of aluminum and zinc coatings hot-dip formed on iron products. In its cognitive aspect, the study offers an in-depth analysis of the partial processes that proceed in metal bath at the solid body – liquid metal interface. It is expected that the present study will help in a more detailed description of the respective phenomena and in full explanation of the mechanism of the coating growth, taking as an example the growth of aluminum coatings. The obtained results can serve as a background for some general conclusions regarding the thickness evolution process in other hot-dip coatings.

  8. Transport properties of iron-porphyrin molecule sandwiched between Au surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Hisashi [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)], E-mail: KONDO.Hisashi@nims.go.jp; Kino, Hiori; Nara, Jun [CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Ohno, Takahisa [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); MANA, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2008-09-30

    The transport properties of an iron-porphyrin molecule sandwiched between Au(1 1 1) electrodes are investigated using the non-equilibrium Green's function method based on the density functional theory, and in particular, the dependence on a terminal-atom position is studied. We consider four models for terminal-atom positions. It is found that the transport properties of the junction system are very sensitive to a terminal-atom position. We also find that the contribution of the d-orbitals of the Fe atom to the transport properties around the Fermi energy strongly changes, depending on a terminal-atom position. From these results, we propose a suitable terminal-atom position for the molecular sensor discussed in the other paper.

  9. Mercury's Surface Magnetic Field Determined from Proton-Reflection Magnetometry

    Science.gov (United States)

    Winslow, Reka M.; Johnson, Catherine L.; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Lillis, Robert J.; Korth, Haje; Slavin, James A.; Solomon, Sean C.; Zurbuchen, Thomas H.; Zuber, Maria T.

    2014-01-01

    Solar wind protons observed by the MESSENGER spacecraft in orbit about Mercury exhibit signatures of precipitation loss to Mercury's surface. We apply proton-reflection magnetometry to sense Mercury's surface magnetic field intensity in the planet's northern and southern hemispheres. The results are consistent with a dipole field offset to the north and show that the technique may be used to resolve regional-scale fields at the surface. The proton loss cones indicate persistent ion precipitation to the surface in the northern magnetospheric cusp region and in the southern hemisphere at low nightside latitudes. The latter observation implies that most of the surface in Mercury's southern hemisphere is continuously bombarded by plasma, in contrast with the premise that the global magnetic field largely protects the planetary surface from the solar wind.

  10. 弱磁性铁矿物表面强磁化研究进展%Research Progress on the Surface Strong Magnetization of Weakly Magnetic Iron Minerals

    Institute of Scientific and Technical Information of China (English)

    罗德强; 刘建

    2016-01-01

    随着易处理铁矿资源的开发利用,弱磁性铁矿所占比重越来越大,并且其矿石类型复杂,这类矿石往往生产成本高、生产过程环境污染严重导致难以有效开发利用,而磁铁矿物表面强磁化技术则成为解决这一问题的重要途径。概述了近年来弱磁性铁矿物表面强磁化研究情况,对弱磁性铁矿物的碱浸磁化、电化学处理磁化、磁种磁化、生物磁化等工艺的研究成果分别进行了详细的介绍,并提出了今后的发展方向。%With highly exploitation and utilization of easily separable iron ores , the proportion of weakly magnetic iron ore containing arsenic is growing larger , which belongs to complex ore proper-ty.Because of high cost and serious environmental pollution of mineral processing , lots of weakly magnetic iron resources can not be effectively utilized .surface strong magnetization of weakly mag-netic iron minerals becomes a particular technology to solve the problem .This article aims to sum-marize research progress on surface strong magnetization of weakly magnetic iron minerals in recent years.Numerous magnetization technologies of weakly magnetic iron minerals , such as alkali leac-hing magnetization , electrochemical treatment magnetization , magnetic seeds magnetization and bi-ological magnetization , were introduced in detail .Finally, the development directions of the surface strong magnetization of weakly magnetic iron minerals in future are proposed based on this review .

  11. The Curious Case of Iron Oxide Nanoparticles in Nature: Determining confidence estimates in sediment records of environmental change

    Science.gov (United States)

    Banerjee, S. K.; Guyodo, Y. J. B.

    2014-12-01

    Modern topsoils, as well as many paleosols, display enhanced induced magnetizations compared to their parent materials. Such enhanced magnetism has been successfully correlated with local Mean Annual Rainfall (MAR), but a generally applicable deduction of MAR from magnetic properties remains difficult to establish. In fact, there are enough cases of observed departures from the above model to warrant a number of provisos that require knowledge of variability in parent material character, precipitation minus evaporation, and perhaps other local data. Another problem is that we lack the knowledge to construct a forward model that proceeds from fundamental parameters like mineralogy, particle size, non-stoichiometry and structural defects. Increasing knowledge about iron oxide, oxyhydroxide and sulfide nanoparticles, likely first stages of parent material alteration, should help in constructing competing forward models as defined above. In this talk we try to learn from observed magnetic behavior of fully characterized synthetic ferrihydrite and lepidocrocite, their alteration to second phases such as goethite, magnetite, maghemite and hematite, as well as further alterations of some secondary phases to more stable ones. We find that the multiple pathways of alteration depend on structural order, impurities, non-stoichiometry and kinetic stability of end products. By ranking the effects of these parameters, we can try to modify current forward models of alteration based on thermodynamic stability of iron oxides in parent materials. The ultimate goal should be to determine degrees of confidence in our claims of past climatic or environmental conditions.

  12. Determining the Extent of Delocalization in Mixed-Valence Iron Dimers using X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, Alison; /Yale U. /SLAC

    2007-11-07

    This study examines the extent of charge delocalization in mixed valence compounds. Understanding the structure of charge delocalization is the first step in understanding the local dynamics of charge transfer. This insight has diverse applications such as the ability to mimic biological reactions and to enhance solar technology. Because of its fast time scale, synchrotron radiation was used to probe the iron K-edge for three organometallic systems. In these complexes, two bridged metal atoms share an effective charge of 5+. In a Robin-Day Class II compound, charge is localized and the two iron atoms have effective oxidation states of 2+ and 3+ respectively. For Class III delocalized compounds each metal center has an effective charge of 2.5+. Class II/III compounds exhibit characteristics of both localized and delocalized systems according to various optical spectroscopies. Synchrotron radiation was used to study charge distribution in these poorly-understood Class II/III intermediate systems. In the limit of absolute localization, spectra of the mixed valence species were expected to be a linear combination of the reduced and oxidized species. For the delocalized case, a linear combination was not expected. These two cases were used as calibration limits to determine the extent of delocalization in the unknown Class II/III compound. Results showed that synchrotron radiation classifies the Class II/III compound as localized. However, data also demonstrated that the linear combination model did not hold as expected and a revised model is necessary to better understand this phenomenon.

  13. Determination of neutron cross sections of iron and water between 0. 3 and 11 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Megahid, R.M.; Gaafar, M.A.; El-Cherif, A.I. (Atomic Energy Authority, Cairo (Egypt). Reactor and Neutron Physics Dept.)

    1981-07-01

    Total neutron cross-sections of iron and water have been determined experimentally using a continuous neutron spectrum emitted from one of the horizontal channels of the ET-RR-1 reactor. Measurements have been carried out using neutron spectrometer with single stilbene scintillator. The gamma background was rejected from the measured pulses by a compensation method based on the differences in the shape of neutrons and gamma pulses. The measured pulse amplitude distributions were transformed to neutron energy distributions by means of a differential method. The measured fast neutron spectrum leaking directly from the reactor core and that transmitted through iron and water barriers were used to evaluate the total cross-sections for neutrons of energies between 0.3 and 11 MeV for these materials. Comparison between the values of obtained cross-sections and that given by others shows that a reasonable agreement could be observed between the two for neutrons of energies >1.5 MeV. However, for neutrons of energies <1.5 MeV a large discrepancy was observed. This could be attributed to the failure of the discriminating technique used in these measurements to separate between neutron and gamma pulses.

  14. Determining the level of heavy metal pollution in surface sediments of the Gulf of Chabahar

    OpenAIRE

    Bazzi, A

    2015-01-01

    Background & Objectives: This paper, discussed the concentrations of heavy metals such as cadmium, copper, lead, zinc, nickel, chromium, iron, and magnesium in surface sediments of the Gulf of Chabahar. Materials & Methods: Samples of coastal sediment and shallow waters were collected from five different stations in summer and winter, 2013. Results: The research found that the concentrations of heavy metals in sediments is more than water, although the concentrations of metals in sedime...

  15. THE EFFECTS OF MAGNETIC FIELD MORPHOLOGY ON THE DETERMINATION OF OXYGEN AND IRON ABUNDANCES IN THE SOLAR PHOTOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Christopher S. [Department of Astrophysical and Planetary Sciences, Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States); Uitenbroek, Han; Criscuoli, Serena [National Solar Observatory, Sunspot, NM 88349 (United States); Rempel, Matthias [High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO 80307 (United States); Rast, Mark P., E-mail: mark.rast@lasp.colorado.edu [Department of Astrophysical and Planetary Sciences, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309 (United States)

    2015-02-01

    We have explored the impact of magnetic fields on the determination of the solar photospheric oxygen and iron abundances using three-dimensional radiation-magnetohydrodynamic (MHD) simulations of convection. Specifically, we examined differences in abundance deduced from three classes of atmospheres simulated with the MURaM code: a pure hydrodynamic (HD) simulation, an MHD simulation with a local dynamo magnetic field that has saturated with an unsigned vertical field strength of 80 G at τ = 1, and an MHD simulation with an initially imposed vertical mean field of 80 G. We use differential equivalent width analysis for diagnosing abundances derived from five oxygen and four iron lines of differing wavelength, oscillator strength, excitation potential, and Landé g-factor, and find that the morphology of the magnetic field is important to the outcome of abundance determinations. The largest deduced abundance differences are found in the vertical mean field simulations, where the O I and Fe I abundance corrections compared to the pure HD case are ∼+0.011 dex and +0.065 dex respectively. Small scale unresolved field resulting from the local dynamo has a smaller impact on abundance determinations, with corrections of –0.0001 dex and +0.0044 dex in the magnetized compared to the pure HD simulations. While the overall influence of magnetic field on abundance estimates is found to be small, we stress that such estimates are sensitive not only to the magnitude of magnetic field but also to its morphology.

  16. Miniaturization of spectrophotometry based on micro flow analysis using norfloxacin as less-toxic reagent for iron determination.

    Science.gov (United States)

    Prasertboonyai, Kanyarak; Arqueropanyo, Orn-Anong; Liawraungrath, Boonsom; Liawraungrath, Saisunee; Pojanakaroon, Teraboon

    2015-01-01

    A micro flow analysis (μFA) system has been designed and fabricated for determination of total iron. The system consists of a microchannels fabricated by etching the polymethyl methacrylate (PMMA) by using laser ablation techniques and a sealed polydimethylsiloxane (PDMS) as top plate. The PMMA micro-flow was topped with a home-made polydimethylsiloxane (PDMS) micro-flow through cell, which was integrated with light emitting diode (LED) as light source and a USB 2000 spectrometer as detector. The proposed μFA system was applied to determination of Fe(III) using norfloxacin as a less-toxic complexing agent in an acetate buffer solution pH 4.0, resulting in a yellow colored complex which gave the maximum absorption at 430nm. Under the optimum conditions, a linear calibration graph was obtained in the concentration range of 0.20-5.00mgL(-1). The limit of detection (LOD, defined as 3σ) and limit of quantification (LOQ, defined as 10σ) were 0.12 and 0.45mgL(-1), respectively. The relative standard deviation (R.S.D.) for repeatability and reproducibility were less than 1.50% and 1.24% (n=11) for 0.2mgL(-1) and 1.0mgL(-1) Fe(III), respectively. The proposed method was successfully applied to the determination of total iron in water samples, validated by the FAAS standard method after digestion by HNO3 and H2O2. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Thermodynamic stability and structures of iron chloride surfaces: A first-principles investigation

    Energy Technology Data Exchange (ETDEWEB)

    Saraireh, Sherin A. [Physics Department, Faculty of Sciences, Al-Hussein Bin Talal University, Ma' an (Jordan); Altarawneh, Mohammednoor, E-mail: M.Altarawneh@Murdoch.edu.au [School of Engineering and Information Technology, Murdoch University, Perth (Australia)

    2014-08-07

    In this study, we report a comprehensive density functional theory investigation of the structure and thermodynamic stability of FeCl{sub 2} and FeCl{sub 3} surfaces. Calculated lattice constants and heats of formation for bulk FeCl{sub 2} and FeCl{sub 3} were found to be in relatively good agreement with experimental measurements. We provide structural parameters for 15 distinct FeCl{sub 2} and FeCl{sub 3} surfaces along the three low-index orientations. The optimized geometries for all surfaces are compared with analogous bulk values. Ab initio atomistic thermodynamic calculations have been carried out to assess the relative thermodynamic stability of FeCl{sub 2} and FeCl{sub 3} surfaces under practical operating conditions of temperatures and pressures. The FeCl{sub 2} (100-Cl) surface is found to afford the most stable configuration at all experimentally accessible gas phase conditions.

  18. Growth and structural determination of He bubbles in iron/chromium alloys using molecular dynamics simulations

    Science.gov (United States)

    Abhishek, A.; Warrier, M.; Ganesh, R.; Caro, A.

    2016-04-01

    Helium(He) produced by transmutation process inside structural material due to neutron irradiation plays a vital role in the degradation of material properties. We have carried out Molecular dynamics(MD) simulations to study the growth of He bubble in Iron-Chromium alloy. Simulations are carried out at two different temperatures, viz. 0.1 K and 800 K, upto He bubble radius of 2.5 nm. An equation for variation of volume of He bubbles with the number of He atoms is obtained at both the temperatures. Bubble pressure and potential energy variation is obtained with increasing bubble radius. Dislocations are also found to be emitted after the bubble reaches a critical radius of 0.39 nm at 800 K. Separate MD simulations of He with pre-created voids are also carried out to study the binding energies of He and Vacancy (V) to Hem-Vn cluster. Binding energies are found to be in the range of 1-5.5 eV.

  19. A pre-concentration procedure using coprecipitation for determination of lead and iron in several samples using flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Saracoglu, S. [Erciyes University, Faculty of Education, 38039 Kayseri (Turkey); Soylak, M. [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey)]. E-mail: soylak@erciyes.edu.tr; Peker, D.S. Kacar [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey); Elci, L. [Pamukkale University, Faculty of Science and Arts, Chemistry Department, 20020 Denizli (Turkey); Santos, W.N.L. dos [Universidade Estadual de Santa Cruz lheus, Bahia (Brazil); Lemos, V.A. [Universidade Estadual do Sudoeste da Bahia, Nucleo de Quimica Analitica da Bahia (NQA), Laboratorio de Quimica Analitica (LQA), Campus de Jequie, 45200-000 Jequie, BA (Brazil); Ferreira, S.L.C. [Instituto de Quimica, Universidade Federal da Bahia, Campus Universitario de Ondina, 40.170-280 Salvador, BA (Brazil)

    2006-08-04

    The present paper proposes a pre-concentration procedure for determination of lead and iron in several samples by flame atomic absorption spectrometry. In it, lead(II) and iron(III) ions are coprecipitated using the violuric acid-copper(II) system as collector. Afterwards, the precipitate is dissolved with 1 M HNO{sub 3} solution and the metal ions are determined. The optimization step was performed using factorial design involving the variables: pH, violuric acid mass (VA) and copper concentration (Cu). Using the optimized experimental conditions, the proposed procedure allows the determination these metals with detection limits of 0.18 {mu}g L{sup -1} for iron and 0.16 {mu}g L{sup -1} for lead. The effects of foreign ions on the pre-concentration procedure were also evaluated and the results demonstrated that this method could be applied for determination of iron and lead in several real samples. The proposed method was successfully applied to the analysis of seawater, urine, mineral water, soil and physiological solution samples. The concentrations of lead and iron achieved in these samples agree well with others data reported in the literature.

  20. Determination of surface electric charge profile in pyroelectric crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ghaderi, R.; Davani, F. Abbasi, E-mail: fabbasi@sbu.ac.ir [Radiation Application Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2014-12-08

    Pyroelectric crystals are used to produce high energy self-focused electron beams. Here, an experimental analysis in combination with simulation studies will be reported to investigate possible sources of this effect. In the experiments, the surface of crystal was divided into six separated parts and the rate of surface electric charge production was measured accordingly. A non-steady and spatially non-uniform distribution of the surface charge generation was observed, in which it tends to a uniform distribution in the course of experiment. The obtained surface electric charges from the experiments were used to simulate the electric field and potential around the crystal by COMSOL Multiphysics. It was observed that emitted electrons from the crystal surface were focused, and the non-uniformity in spatial charge is responsible for this phenomenon.

  1. Determination of apparent sampling thickness of sea surface microlayer

    Science.gov (United States)

    Li, Jun; Ding, Hai-Bing; Wu, Zhi-Jian; Zhang, Zheng-Bin; Liu, Lian-Sheng

    1998-06-01

    In situ and laboratory studies of sea—surface microlayer sampling methods using glass plate, rotating drum, screen and funnel samplers were conducted. For glass plate and rotating drum samplers, surface microlayer samples of different thickness were collected by controlling their withdrawal rate and rotating rate. The relationships between pH, surface tension, the concentration of dissolved trace metals Cu and Pb, phosphate, particulate matters and sampling thickness were carefully investigated. It was shown that physicochemical and biological properties change obviously at the sampling thickness of about 50 μm, which is consistent with the mean thickness of the boundary film in the models of gas exchange across the sea surface. It is proposed that the apparent sampling thickness of the surface microlayer should be less than 40 μm. The factors affecting the sampling thickness are discussed, and the feasibility and applicable conditions for different sampling methods are evaluated.

  2. Effects of 1000 C oxide surfaces on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Buchanan, R.A.; Perrin, R.L. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering

    1997-12-01

    Results of electrochemical aqueous-corrosion studies at room temperature indicate that retained in-service-type high-temperature surface oxides (1000 C in air for 24 hours) on FA-129, FAL and FAL-Mo iron aluminides cause major reductions in pitting corrosion resistance in a mild acid-chloride solution designed to simulate aggressive atmospheric corrosion. Removal of the oxides by mechanical grinding restores the corrosion resistance. In a more aggressive sodium tetrathionate solution, designed to simulate an aqueous environment contaminated by sulfur-bearing combustion products, only active corrosion occurs for both the 1000 C oxide and mechanically cleaned surfaces at FAL. Results of slow-strain-rate stress-corrosion-cracking tests on FA-129, FAL and FAL-Mo at free-corrosion and hydrogen-charging potentials in the mild acid chloride solution indicate somewhat higher ductilities (on the order of 50%) for the 1000 C oxides retard the penetration of hydrogen into the metal substrates and, consequently, are beneficial in terms of improving resistance to environmental embrittlement. In the aggressive sodium tetrathionate solution, no differences are observed in the ductilities produced by the 1000 C oxide and mechanically cleaned surfaces for FAL.

  3. Surface properties of self-assembled monolayer films of tetra-substituted cobalt, iron and manganese alkylthio phthalocyanine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Akinbulu, Isaac Adebayo; Khene, Samson [Department of Chemistry, Rhodes University, Grahamstown 6140 (South Africa); Nyokong, Tebello, E-mail: t.nyokong@ru.ac.z [Department of Chemistry, Rhodes University, Grahamstown 6140 (South Africa)

    2010-09-30

    Self-assembled monolayer (SAM) films of iron (SAM-1), cobalt (SAM-2) and manganese (SAM-3) phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the non-peripheral positions, were formed on gold electrode in dimethylformamide (DMF). Electrochemical, impedimentary and surface properties of the SAM films were investigated. Cyclic voltammetry was used to investigate the electrochemical properties of the films. Ability of the films to inhibit common faradaic processes on bare gold surface (gold oxidation, solution redox chemistry of [Fe(H{sub 2}O){sub 6}]{sup 3+}/[Fe(H{sub 2}O){sub 6}]{sup 2+} and underpotential deposition (UDP) of copper) was investigated. Electrochemical impedance spectroscopy (EIS), using [Fe(CN){sub 6}]{sup 3-/4-} redox process as a probe, offered insights into the electrical properties of the films/electrode interfaces. Surface properties of the films were probed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The films were employed for the electrocatalytic oxidation of the pesticide, carbofuran. Electrocatalysis was evidenced from enhanced current signal and less positive oxidation potential of the pesticide on each film, relative to that observed on the bare gold electrode. Mechanism of electrocatalytic oxidation of the pesticide was studied using rotating disc electrode voltammetry.

  4. Properties of surface functionalized iron oxide nanoparticles (ferrofluid) conjugated antibody for lateral flow immunoassay application

    Energy Technology Data Exchange (ETDEWEB)

    Nor, Noorhashimah Mohamad [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Abdul Razak, Khairunisak, E-mail: khairunisak@eng.usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); NanoBiotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), 11800 USM, Penang (Malaysia); Tan, Soo Choon; Noordin, Rahmah [NanoBiotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), 11800 USM, Penang (Malaysia)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer The effects of acid functionalization and biocompatible polymer on iron oxide nanoparticles (IONPs) ferrofluid were studied. Black-Right-Pointing-Pointer The IONPs functionalized using citric acid (IONPs-CA) is the most stable ferrofluid with zeta potential value of -49 mV. Black-Right-Pointing-Pointer IONPs-CA can be directly conjugated with antibody without biocompatible polymer coating. Black-Right-Pointing-Pointer IONPs-CA had optimum detection efficiency of 15 min assay time. Black-Right-Pointing-Pointer IONPs-CA showed the highest colour intensity in labelling lateral flow immunoassay. - Abstract: In this study, colloidal stability of iron oxide nanoparticles (IONPs) with several acid functionalizations and biocompatible polymer coating were compared for use as labelling agent in lateral flow immunoassay (LFIA). IONPs were synthesized using the precipitation method and peptized using perchloric acid (PA), nitric acid (NA) and citric acid (CA) to form a stable IONPs ferrofluid. Steric stabilization of IONPs using silane polyethelene glycol (SiPEG) was developed to improve biocompatibility and provide spaces for subsequent conjugation process. From the transmission electron microscopy (TEM) images, the sizes of IONPs obtained with different acids peptization were in range of 11-17 nm. The IONPs peptized using citric acid showed the most stable ferrofluid condition at physiological condition with zeta potential value of -49 mV. The LFIA was also developed to examine the conjugation properties of IONPs to mouse anti-human IgG{sub 4} antibody (M{alpha}HIgG{sub 4}). IONPs functionalized with citric acid can be directly conjugated with the M{alpha}HIgG{sub 4} without the need of SiPEG addition. This is due to the presence of the carboxylic group that acted as a ligand to the extended bond formation with the antibody. Moreover, the conjugation of IONPs with M{alpha}HIgG{sub 4} was also tested in a LFIA to detect brugian

  5. Blocked-micropores, surface functionalized, bio-compatible and silica-coated iron oxide nanocomposites as advanced MRI contrast agent

    Energy Technology Data Exchange (ETDEWEB)

    Darbandi, Masih, E-mail: masih.darbandi@uni-due.de [Vanderbilt University, Department of Physics and Vanderbilt Institute of Nanoscale Science and Engineering (VINSE) (United States); Laurent, Sophie [University of Mons, Department of General, Organic and Biomedical Chemistry NMR and Molecular Imaging Laboratory (Belgium); Busch, Martin [University of Duisburg-Essen, Nanoparticle Process Technology, Faculty of Engineering and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Li Zian [University of Duisburg-Essen, Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Yuan Ying; Krueger, Michael [University of Freiburg, Department of Microsystems Engineering and Freiburg Materials Research Centre (Germany); Farle, Michael [University of Duisburg-Essen, Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Winterer, Markus [University of Duisburg-Essen, Nanoparticle Process Technology, Faculty of Engineering and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Vander Elst, Luce; Muller, Robert N. [University of Mons, Department of General, Organic and Biomedical Chemistry NMR and Molecular Imaging Laboratory (Belgium); Wende, Heiko [University of Duisburg-Essen, Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany)

    2013-05-15

    Biocompatible magnetic nanoparticles have been found promising in several biomedical applications for tagging, imaging, sensing and separation in recent years. In this article, a systematic study of the design and development of surface-modification schemes for silica-coated iron oxide nanoparticles (IONP) via a one-pot, in situ method at room temperature is presented. Silica-coated IONP were prepared in a water-in-oil microemulsion, and subsequently the surface was modified via addition of organosilane reagents to the microemulsion system. The structure and the morphology of the as synthesized nanoparticles have been investigated by means of transmission electron microscopy (TEM) and measurement of N{sub 2} adsorption-desorption. Electron diffraction and high-resolution transmission electron microscopic (TEM) images of the nanoparticles showed the highly crystalline nature of the IONP structures. Nitrogen adsorption indicates microporous and blocked-microporous structures for the silica-coated and amine functionalized silica-coated IONP, respectively which could prove less cytotoxicity of the functionalized final product. Besides, the colloidal stability of the final product and the presence of the modified functional groups on top of surface layer have been proven by zeta-potential measurements. Owing to the benefit from the inner IONP core and the hydrophilic silica shell, the as-synthesized nanocomposites were exploited as an MRI contrast enhancement agent. Relaxometric results prove that the surface functionalized IONP have also signal enhancement properties. These surface functionalized nanocomposites are not only potential candidates for highly efficient contrast agents for MRI, but could also be used as ultrasensitive biological-magnetic labels, because they are in nanoscale size, having magnetic properties, blocked-microporous and are well dispersible in biological environment.

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

    Science.gov (United States)

    Vongboot, Monnapat; Suesoonthon, Monrudee

    2015-01-01

    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 500 nm by UV visible spectrophotometer. In this study, it was found that Cu(II) and Fe(III) were completely to form complexes with 400 mmol/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 30.00 mg/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 14.78 mg/g.

  7. Shock Melting of Iron Silicide as Determined by In Situ X-ray Diffraction.

    Science.gov (United States)

    Newman, M.; Kraus, R. G.; Wicks, J. K.; Smith, R.; Duffy, T. S.

    2016-12-01

    The equation of state of core alloys at pressures and temperatures near the solid-liquid coexistence curve is important for understanding the dynamics at the inner core boundary of the Earth and super-Earths. Here, we present a series of laser driven shock experiments on textured polycrystalline Fe-15Si. These experiments were conducted at the Omega and Omega EP laser facilities. Particle velocities in the Fe-15Si samples were measured using a line VISAR and were used to infer the thermodynamic state of the shocked samples. In situ x-ray diffraction measurements were used to probe the melting transition and investigate the potential decomposition of Fe-15Si in to hcp and B2 structures. This work examines the kinetic effects of decomposition due to the short time scale of dynamic compression experiments. In addition, the thermodynamic data collected in these experiments adds to a limited body of information regarding the equation of state of Fe-15Si, which is a candidate for the composition in Earth's outer core. Our experimental results show a highly textured solid phase upon shock compression to pressures ranging from 170 to 300 GPa. Below 320 GPa, we observe diffraction peaks consistent with decomposition of the D03 starting material in to an hcp and a cubic (potentially B2) structure. Upon shock compression above 320 GPa, the intense and textured solid diffraction peaks give way to diffuse scattering and loss of texture, consistent with melting along the Hugoniot. When comparing these results to that of pure iron, we can ascertain that addition of 15 wt% silicon increases the equilibrium melting temperature significantly, or that the addition of silicon significantly increases the metastability of the solid phase, relative to the liquid. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  8. Curvature-induced symmetry breaking determines elastic surface patterns.

    Science.gov (United States)

    Stoop, Norbert; Lagrange, Romain; Terwagne, Denis; Reis, Pedro M; Dunkel, Jörn

    2015-03-01

    Symmetry-breaking transitions associated with the buckling and folding of curved multilayered surfaces-which are common to a wide range of systems and processes such as embryogenesis, tissue differentiation and structure formation in heterogeneous thin films or on planetary surfaces-have been characterized experimentally. Yet owing to the nonlinearity of the underlying stretching and bending forces, the transitions cannot be reliably predicted by current theoretical models. Here, we report a generalized Swift-Hohenberg theory that describes wrinkling morphology and pattern selection in curved elastic bilayer materials. By testing the theory against experiments on spherically shaped surfaces, we find quantitative agreement with analytical predictions for the critical curves separating labyrinth, hybrid and hexagonal phases. Furthermore, a comparison to earlier experiments suggests that the theory is universally applicable to macroscopic and microscopic systems. Our approach builds on general differential-geometry principles and can thus be extended to arbitrarily shaped surfaces.

  9. Determination of Reactive Surface Area of Melt Glass

    Energy Technology Data Exchange (ETDEWEB)

    Bourcier,W.L.; Roberts, S.; Smith, D.K.; Hulsey, S.; Newton,L.; Sawvel, A.; Bruton, C.; Papelis, C.; Um, W.; Russell, C. E.; Chapman,J.

    2000-10-01

    A comprehensive investigation of natural and manmade silicate glasses, and nuclear melt glass was undertaken in order to derive an estimate of glass reactive surface area. Reactive surface area is needed to model release rates of radionuclides from nuclear melt glass in the subsurface. Because of the limited availability of nuclear melt glasses, natural volcanic glass samples were collected which had similar textures and compositions as those of melt glass. A flow-through reactor was used to measure the reactive surface area of the analog glasses in the presence of simplified NTS site ground waters. A measure of the physical surface area of these glasses was obtained using the BET gas-adsorption method. The studies on analog glasses were supplemented by measurement of the surface areas of pieces of actual melt glass using the BET method. The variability of the results reflect the sample preparation and measurement techniques used, as well as textural heterogeneity inherent to these samples. Based on measurements of analog and actual samples, it is recommended that the hydraulic source term calculations employ a range of 0.001 to 0.01 m{sup 2}/g for the reactive surface area of nuclear melt glass.

  10. Determining Titan surface topography from Cassini SAR data

    Science.gov (United States)

    Stiles, Bryan W.; Hensley, Scott; Gim, Yonggyu; Bates, David M.; Kirk, Randolph L.; Hayes, Alex; Radebaugh, Jani; Lorenz, Ralph D.; Mitchell, Karl L.; Callahan, Philip S.; Zebker, Howard; Johnson, William T.K.; Wall, Stephen D.; Lunine, Jonathan I.; Wood, Charles A.; Janssen, Michael; Pelletier, Frederic; West, Richard D.; Veeramacheneni, Chandini

    2009-01-01

    A technique, referred to as SARTopo, has been developed for obtaining surface height estimates with 10 km horizontal resolution and 75 m vertical resolution of the surface of Titan along each Cassini Synthetic Aperture Radar (SAR) swath. We describe the technique and present maps of the co-located data sets. A global map and regional maps of Xanadu and the northern hemisphere hydrocarbon lakes district are included in the results. A strength of the technique is that it provides topographic information co-located with SAR imagery. Having a topographic context vastly improves the interpretability of the SAR imagery and is essential for understanding Titan. SARTopo is capable of estimating surface heights for most of the SAR-imaged surface of Titan. Currently nearly 30% of the surface is within 100 km of a SARTopo height profile. Other competing techniques provide orders of magnitude less coverage. We validate the SARTopo technique through comparison with known geomorphological features such as mountain ranges and craters, and by comparison with co-located nadir altimetry, including a 3000 km strip that had been observed by SAR a month earlier. In this area, the SARTopo and nadir altimetry data sets are co-located tightly (within 5-10 km for one 500 km section), have similar resolution, and as expected agree closely in surface height. Furthermore the region contains prominent high spatial resolution topography, so it provides an excellent test of the resolution and precision of both techniques.

  11. Simulation method for determining biodegradation in surface waters

    Energy Technology Data Exchange (ETDEWEB)

    Schoeberl, P.; Guhl, W. [Henkel KGaA, Duesseldorf (Germany). Hauptabteilung Oekologie; Scholz, N. [OXENO GmbH, Marl (Germany); Taeger, K. [BASF AG, Ludwigshafen am Rhein (Germany)

    1998-07-01

    OECD guidelines and EU directives on the biological testing of chemicals contain no methods able to simulate biodegradation in surface waters. The surface water simulation method presented in this paper is suitable for closing this gap. The species in the autochthonous biocoenosis used in the method form part of the food web in natural surface waters. The microbial degradation activity measured by the half-life is comparable with that in surface waters. The degrees of degradation measured in this surface water simulation method can be applied to natural surface waters. (orig.) [Deutsch] Die OECD- und EU-Richtlinien zur biologischen Pruefung von Chemikalien enthalten kein Verfahren, mit dem der biologische Abbau in Fliessgewaessern simuliert werden kann. Das in dieser Arbeit vorgestellte Fliessgewaesser-Simulationsmodell ist geeignet, diese Luecke zu schliessen. Die Arten der autochthonen Biocoenose des Modells sind Glieder im Nahrungsnetz natuerlicher Fliessgewaesser. Die an der Halbwertszeit gemessene mikrobielle Abbauaktivitaet ist mit derjenigen in Fliessgewaessern vergleichbar. Die im Fliessgewaesser-Simulationsmodell gemessenen Abbaugrade sind auf natuerliche Fliessgewaesser uebertragbar. (orig.)

  12. Influence of siderophore pyoverdine synthesis and iron-uptake on abiotic and biotic surface colonization of Pseudomonas putida S11.

    Science.gov (United States)

    Ponraj, Paramasivan; Shankar, Manoharan; Ilakkiam, Devaraj; Gunasekaran, Paramasamy

    2012-12-01

    Fluorescent pseudomonads produce a characteristic fluorescent pigment, pyoverdines as their primary siderophore for iron acquisition under iron-limiting conditions. Here, we report the identification of a random transposon mutant IST3 of Pseudomonas putida S11 showing tolerance to iron starvation stress condition and increased pyoverdine production. The insertion of the Tn5 transposon was found to be in pstS gene of pstSR operon encoding sensor histidine kinase protein of the two-component signal transduction system. A pyoverdine negative derivative of IST3 mutant constructed was sensitive to iron stress condition. It indicated that increased survival of IST3 under iron-limiting condition was due to higher pyoverdine production. The iron starvation tolerant mutant (IST3) exhibited enhanced pyoverdine-mediated iron uptake in minimal medium which significantly improved its biofilm formation, seed adhesion and competitive root colonization.

  13. A pre-concentration procedure using coprecipitation for determination of lead and iron in several samples using flame atomic absorption spectrometry

    OpenAIRE

    Ferreira, Sergio Luis Costa; Saracoglu, S.; Soylak, Mustafa; Peker, D. S. Kacar; Elci, L.; Santos, W. N. L. dos; Lemos, Valfredo Azevedo

    2006-01-01

    Texto completo: acesso restrito. p.133–137 The present paper proposes a pre-concentration procedure for determination of lead and iron in several samples by flame atomic absorption spectrometry. In it, lead(II) and iron(III) ions are coprecipitated using the violuric acid–copper(II) system as collector. Afterwards, the precipitate is dissolved with 1 M HNO3 solution and the metal ions are determined. The optimization step was performed using factorial design involving the variables: pH, v...

  14. Spectrophotometric determination of iron species using a combination of artificial neural networks and dispersive liquid-liquid microextraction based on solidification of floating organic drop

    Energy Technology Data Exchange (ETDEWEB)

    Moghadam, Masoud Rohani; Shabani, Ali Mohammad Haji [Chemistry Department, Faculty of Science, Yazd University, Yazd (Iran, Islamic Republic of); Dadfarnia, Shayessteh, E-mail: sdadfarnia@yazduni.ac.ir [Chemistry Department, Faculty of Science, Yazd University, Yazd (Iran, Islamic Republic of)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Combination of DLLME-SFO/fiber optic-linear array detection/chemometric methods. Black-Right-Pointing-Pointer Simultaneous determination of complexes with overlapping spectra. Black-Right-Pointing-Pointer A novel DLLME-SFO method is proposed for extraction of iron species. Black-Right-Pointing-Pointer The extracted iron species are simultaneous determined using PC-ANNs. Black-Right-Pointing-Pointer The enhancement factor of 162 and 125 are achieved for Fe{sup 3+} and Fe{sup 2+}, respectively. - Abstract: A dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and artificial neural networks method was developed for the simultaneous separation/preconcentration and speciation of iron in water samples. In this method, an appropriate mixture of ethanol (as the disperser solvent) and 1-undecanol (as the extracting solvent) containing appropriate amount of 2-thenoyltrifluoroacetone (TTA) (as the complexing agent) was injected rapidly into the water sample containing iron (II) and iron (III) species. At this step, the iron species interacted with the TTA and extracted into the 1-undecanol. After the phase separation, the absorbance of the extracted irons was measured in the wavelength region of 450-600 nm. The artificial neural networks were then applied for simultaneous determination of individual iron species. Under optimum conditions, the calibration graphs were linear in the range of 95-1070 {mu}g L{sup -1} and 31-350 {mu}g L{sup -1} with detection limits of 25 and 8 {mu}g L{sup -1} for iron (II) and iron (III), respectively. The relative standard deviations (R.S.D., n = 6) were lower than 4.2%. The enhancement factor of 162 and 125 were obtained for Fe{sup 3+} and Fe{sup 2+} ions, respectively. The procedure was applied to power plant drum water and several potable water samples; and accuracy was assessed through the recovery experiments and independent analysis by graphite

  15. Ionic liquid-based extraction followed by graphite-furnace atomic absorption spectrometry for the determination of trace heavy metals in high-purity iron metal.

    Science.gov (United States)

    Matsumiya, Hiroaki; Kato, Tatsuya; Hiraide, Masataka

    2014-02-01

    The analysis of high-purity materials for trace impurities is an important and challenging task. The present paper describes a facile and sensitive method for the determination of trace heavy metals in high-purity iron metal. Trace heavy metals in an iron sample solution were rapidly and selectively preconcentrated by the extraction into a tiny volume of an ionic liquid [1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide] for the determination by graphite-furnace atomic absorption spectrometry (GFAAS). A nitrogen-donating neutral ligand, 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ), was found to be effective in the ionic liquid-based selective extraction, allowing the nearly complete (~99.8%) elimination of the iron matrix. The combination with the optimized GFAAS was successful. The detectability reached sub-μg g(-1) levels in iron metal. The novel use of TPTZ in ionic liquid-based extraction followed by GFAAS was successfully applied to the determination of traces of Co, Ni, Cu, Cd, and Pb in certified reference materials for high-purity iron metal. © 2013 Published by Elsevier B.V.

  16. Validation of a continuous flow method for the determination of soluble iron in atmospheric dust and volcanic ash.

    Science.gov (United States)

    Simonella, Lucio E; Gaiero, Diego M; Palomeque, Miriam E

    2014-10-01

    Iron is an essential micronutrient for phytoplankton growth and is supplied to the remote areas of the ocean mainly through atmospheric dust/ash. The amount of soluble Fe in dust/ash is a major source of uncertainty in modeling-Fe dissolution and deposition to the surface ocean. Currently in the literature, there exist almost as many different methods to estimate fractional solubility as researchers in the field, making it difficult to compare results between research groups. Also, an important constraint to evaluate Fe solubility in atmospheric dust is the limited mass of sample which is usually only available in micrograms to milligrams amounts. A continuous flow (CF) method that can be run with low mass of sediments (deposited volcanic ash. Both materials tested are easy eroded by wind and are representative of atmospheric dust/ash exported from this region. The uncertainty of the CF method was obtained from seven replicates of one surface sediment sample, and shows very good reproducibility. The replication was conducted on different days in a span of two years and ranged between 8 and 22% (i.e., the uncertainty for the standard method was 6-19%). Compared to other standardized methods, the CF method allows studies of dissolution kinetic of metals and consumes less reagents and time (dust/ash.

  17. Application of response surface methodology for optimization of azocarmine B removal by heterogeneous photo-Fenton process using hydroxy-iron-aluminum pillared bentonite

    Science.gov (United States)

    Xu, Tianyuan; Liu, Yun; Ge, Fei; Liu, Lin; Ouyang, Yuting

    2013-09-01

    Hydroxy-iron-aluminum pillared bentonite (H-Fe-Al-B) was synthesized with ion exchange method, and its catalyst characteristics were analyzed by using X-ray diffraction (XRD) and X-ray photoelectron spectrometry (XPS). The photo-Fenton catalytic activity of H-Fe-Al-B was tested under different reaction condition using azocarmine B (ACB) as model pollutant under ultraviolet light (UV) irradiation. The effects of three operating variables, initial dye concentration, initial pH value and H2O2 concentration on the decolorization efficiency of ACB were optimized by response surface methodology (RSM) based on Box-Behnken design. The results showed that hydroxy aluminum iron ions intercalated into the interlayer spaces of bentonite successfully and H-Fe-Al-B had high photocatalytic activity. Analysis of variance (ANOVA) indicated that the proposed quadratic model could be used to navigate the design space. The proposed model was approximately in accordance with the experimental case with correlation coefficients R2, Radj2 and Rpred2 correlation coefficients of 0.9996, 0.9991 and 0.9934, respectively. The optimum conditions for ACB decolorization were dye concentration of 143.7 mg/L, pH of 4.2 and H2O2 concentration of 17.7 mM, respectively. The predicted decolorization rate under the optimum conditions determined by the proposed model was 99.6%. Confirmatory tests were carried out under the optimum conditions and the decolorization rate of 99.5% was observed, which closely agreed with the predicted value.

  18. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2011-01-01

    White Cast Iron (Ⅰ) White cast iron or ‘white iron' refers to the type of cast iron in which all of the carbon exists as carbide;there is no graphite in the as-cast structure and the fractured surface shows a white colour.White cast iron can be divided in three classes:· Normal white cast iron — this iron contains only C,Si,Mn,P and S,with no other alloying elements.· Low-alloy white cast iron — the total mass fraction of alloying elements is less than 5%.

  19. Surface Reactivity of Iron Oxide Pigmentary Powders toward Atmospheric Components: XPS and Gravimetry of Oxygen and Water Vapor Adsorption

    Science.gov (United States)

    Ismail; Cadenhead; Zaki

    1996-11-10

    The adsorption of oxygen and water vapor on a number of specially prepared alpha-Fe2O3 samples was measured gravimetrically at 25°C. The samples themselves were prepared from a steel-pickling chemical waste (97 wt% FeSO4·7H2O) by roasting the original material at 700°C for 5 h in air, oxygen, and nitrogen. Estimated surface coverages by the adsorbed oxygen and water vapor were made on the basis of nitrogen-adsorption-based surface areas, while the nature of the sample surfaces was investigated by both X-ray photoelectron spectroscopy (XPS) and field emission SEM (FESEM) techniques. In addition a depth profiling study utilizing a sputtering argon beam and XPS was undertaken. Morphological studies using FESEM showed that, while the surface areas were essentially the same (27-29 m2/g) for all three samples, the sample prepared in nitrogen had a significantly larger particle size than the other two. These studies also indicated that neither oxygen nor water vapor adsorption caused any significant structural changes. The differing sample preparations resulted in differing oxygenated surfaces for the alpha-Fe2O3 samples, with the degree of oxygenation decreasing in the order of preparatory gases: oxygen, (wet) air, nitrogen. The amounts of both oxygen and water vapor adsorbed were in inverse proportion to the original degree of surface oxygenation, though the amounts of both represented fractional coverage at best. While the water vapor adsorption was always greater than that of oxygen, the former was more weakly adsorbed, as was indicated by the ease of desorption. Depth profiling failed to indicate any bulk diffusion of oxygen but could not be considered reliable since even the attenuated argon beam used here still brought about reduction of surface iron. Both oxygen and dissociative water adsorption are thought to involve surface sites of high coordination unsaturation. Oxygen is postulated to adsorb on such poorly oxygenated sites primarily as O-2; however, O2

  20. The Use of GPR in Delineating an Iron Sand Boundary and the Determination of Its Electromagnetic Wave Velocity: A Case Study in Jepara, Central Java

    Directory of Open Access Journals (Sweden)

    S. Bijaksana

    2005-11-01

    Full Text Available Exploring the vertical extent of iron sand deposit is challenging as conventional geophysical methods (electrical resistivity, geomagnetic, and seismic refraction are inappropriate and unsuccessful in delineating the iron sand deposit from the bedrock. Ground-penetrating radar (GPR offers a solution to the above problem as radar is not affected negatively by the physical properties of iron sand. In the year 2003, a RAMAC’s GPR survey was carried out in the coast of Bayuran in the Regency of Jepara, Central Java to map the distribution of sub-bottom iron sand. The sand is highly magnetic. The survey used 100 MHz antennas. The survey is also complimented by a novel method in determining the electromagnetic (EM wave velocity of iron sand. Combination of reflection profiling and CMP sounding was deployed. Results of CMP sounding were processed using CMP-semblance analysis that produces the RMS velocity in velocity-time spectra. The RMS velocity is then converted to interval velocity using Dix’s formula and is found to be about 135 mm/ns. Meanwhile, combination of magnetic susceptibility, relative permittivity, and dissipation factors produces radiowaves velocity of iron sand as a function of frequency. The velocities of radiowaves estimated from laboratory match that estimated from CMP analysis.

  1. What happens when iron becomes wet? Observation of reactions at interfaces between liquid and metal surfaces

    CERN Document Server

    Kimura, M

    2003-01-01

    Synchrotron-radiation has been applied to investigation of interfaces between liquid and metal surfaces, with a special attention to corrosion. Three topics are shown: (1) nano structures of rusts formed on steel after atmospheric corrosion. Evolution of 'Fe(O, OH) sub 6 network' is the key to understand how the durable rusts prevent from formation of more rusts. (2) In situ observation of reactions at the interface has been carried out for localized corrosion of stainless steel. It is shown that change in states of Cr sup 3 sup + and Br sup - ions near the interface is deeply related with a breakout of the passivation film. (3) A structural phase transformation on a Cu sub 3 Au(001) surface was investigated. Ordering remains even at a temperature higher than the bulk-critical temperature, showing surface-induced ordering. These approaches gives us crucial information for a new steel-product. (author)

  2. Trace surface analysis with Pico-Coulomb ion fluences: direct detection of multiphoton ionized iron atoms from iron-doped silicon targets

    Energy Technology Data Exchange (ETDEWEB)

    Pellin, M.J.; Young, C.E.; Calaway, W.F.; Gruen, D.M.

    1984-01-01

    A system for surface analysis is described which has the objective of maximizing the probability of detection of atoms sputtered from the sample. Resonance ionization techniques have been combined with pulsed ion-induced erosion to detect and count Fe atoms sputtered from Fe and Fe in Si samples without the interposition of a mass spectrometer between the target and the detector (direct detection). At present, surface analysis by resonance ionization of sputtered atoms (SARISA) allows determination at the fifty parts per million (ppm) level of Fe doped into Si with removal of less than 10/sup -5/ of a monolayer. Separation of the Fe impurity from the isobaric Si/sub 2/ dimers is accomplished in the resonant photo-excitation step. Improvements in the method are suggested which, if successful, would bring the sensitivity into the parts per billion (ppb) range with primary ion currents remaining low enough to produce negligible surface damage. The quantitative and element specific nature of the SARISA technique is established by demonstrating that the ground state neutral fraction is essentially unchanged in two very different matrixes (Fe and Si). Also presented are measurements of the low-lying excited state fraction of Fe atoms sputtered both from an Fe and a Si matrix. 45 references, 5 figures, 2 tables.

  3. Surface, electrical and mechanical modifications of PMMA after implantation with laser produced iron plasma ions

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Qazi Salman; Bashir, Shazia, E-mail: shaziabashir@gcu.edu.pk; Jalil, Sohail Abdul; Shabbir, Muhammad Kaif; Mahmood, Khaliq; Akram, Mahreen; Khalid, Ayesha; Yaseen, Nazish; Arshad, Atiqa

    2016-07-01

    Laser Produced Plasma (LPP) was employed as an ion source for the modifications in surface, electrical and mechanical properties of poly methyl (methacrylate) PMMA. For this purpose Nd:YAG laser (532 nm, 6 ns, 10 Hz) at a fluence of 12.7 J/cm{sup 2} was employed to generate Fe plasma. The fluence and energy measurements of laser produced Fe plasma ions were carried out by employing Thomson Parabola Technique in the presence of magnetic field strength of 0.5 T, using CR-39 as Solid State Nuclear Track Detector (SSNTD). It has been observed that ion fluence ejecting from ablated plasma was maximum at an angle of 5° with respect to the normal to the Fe target surface. PMMA substrates were irradiated with Fe ions of constant energy of 0.85 MeV at various ion fluences ranging from 3.8 × 10{sup 6} ions/cm{sup 2} to 1.8 × 10{sup 8} ions/cm{sup 2} controlled by varying laser pulses from 3000 to 7000. Optical microscope and Scanning Electron Microscope (SEM) were utilized for the analysis of surface features of irradiated PMMA. Results depicted the formation of chain scission, crosslinking, dendrites and star like structures. To explore the electrical behavior, four probe method was employed. The electrical conductivity of ion irradiated PMMA was increased with increasing ion fluence. The surface hardness was measured by shore D hardness tester and results showed the monotonous increment in surface hardness with increasing ion fluence. The increasing trend of surface hardness and electrical conductivity with increasing Fe ion fluence has been well correlated with the surface morphology of ion implanted PMMA. The temperature rise of PMMA surface due to Fe ion irradiation is evaluated analytically and comes out to be in the range of 1.72 × 10{sup 4} to 1.82 × 10{sup 4} K. The values of total Linear Energy Transfer (LET) or stopping power of 0.8 MeV Fe ions in PMMA is 61.8 eV/Å and their range is 1.34 μm evaluated by SRIM simulation.

  4. Modulatory Role of Surface Coating of Superparamagnetic Iron Oxide Nanoworms in Complement Opsonization and Leukocyte Uptake

    DEFF Research Database (Denmark)

    Inturi, Swetha; Wang, Guankui; Chen, Fangfang

    2015-01-01

    Notwithstanding rapid advances of nanotechnology in diagnostic imaging and drug delivery, the engineered nanocarriers still exhibit substantial lack of hemocompatibility. Thus, when injected systemically, nanoparticles are avidly recognized by blood leukocytes and platelets, but the mechanisms of...... alternative pathway and by nanoparticle surface coating. These results provide important insights into the mechanisms of hemocompatibility of nanomedicines....... demonstrated that neutrophils, monocytes, lymphocytes and eosinophils took up SPIO NWs, and the uptake was prevented by EDTA (a general complement inhibitor) and by antiproperdin antibody (an inhibitor of the alternative pathway of the complement system). Cross-linking and hydrogelation of SPIO NWs surface...

  5. Surface modification of graphite-encapsulated iron nanoparticles by RF excited Ar/NH3 gas mixture plasma and their application to Escherichia coli capture

    Science.gov (United States)

    Viswan, Anchu; Chou, Han; Sugiura, Kuniaki; Nagatsu, Masaaki

    2016-09-01

    Graphite-encapsulated iron nanoparticles with an average diameter of 20 nm were synthesized using the DC arc discharge method. For biomedical application, the nanoparticles were functionalized with amino groups using an inductively coupled radio-frequency (RF) plasma. The Ar, NH3, and Ar/NH3 plasmas that were used for functionalization were diagnosed using optical emission spectroscopy, confirming the presence of the required elements. The best conditions for functionalization were optimized by changing various parameters. The pretreatment time with Ar plasma was varied from 0 to 12.5 min, the post-treatment time from 30 s to 3 min. The dependence of the RF power and the gas mixture ratio of Ar/NH3 on the amino group population was also analyzed. From Raman spectroscopy, x-ray photoelectron spectroscopy, and determination of absolute number of amino groups through chemical derivatization, it was found that 5 min of Ar pretreatment and 6%NH3/94%Ar plasma post-treatment for 3 min with an RF power of 80 W gives the best result of about 5  ×  104 amino groups per particle. The nanoparticles that were amino functionalized under optimized conditions and immobilized with an Escherichia coli (E.coli) antibody on their surface were incubated with E.coli bacteria to determine the efficiency of collection by direct culture assay.

  6. Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Mikhlin, Yuri, E-mail: yumikh@icct.ru [Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of sciences, Akademgorodok, 50/24, Krasnoyarsk, 660036 (Russian Federation); Tomashevich, Yevgeny [Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of sciences, Akademgorodok, 50/24, Krasnoyarsk, 660036 (Russian Federation); Vorobyev, Sergey [Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of sciences, Akademgorodok, 50/24, Krasnoyarsk, 660036 (Russian Federation); Siberian Federal University, Svobodny pr. 79, Krasnoyarsk, 660041 (Russian Federation); Saikova, Svetlana [Siberian Federal University, Svobodny pr. 79, Krasnoyarsk, 660041 (Russian Federation); Romanchenko, Alexander [Institute of Chemistry and Chemical Technology of the Siberian Branch of the Russian Academy of sciences, Akademgorodok, 50/24, Krasnoyarsk, 660036 (Russian Federation); Félix, Roberto [Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Lise-Meitner-Campus, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

    2016-11-30

    Highlights: • Pyrite and pyrrhotite in-air abraded and etched in aqueous Fe{sup 3+} solution were studied. • HAXPES (2 keV-6 keV) and Fe K-, S K-edge XANES (TEY and PFY mode) were measured. • Outer “polysulfide”, strongly S-excessive layers are no more than 1–4 nm thick. • “Metal-depleted” layers depend on the treatment and differ for pyrite and pyrrhotite. • Extended nearly-stoichiometric “defective” underlayers were detected using TEY XANES. - Abstract: Hard X-ray photoelectron spectroscopy (HAXPES) using an excitation energy range of 2 keV to 6 keV in combination with Fe K- and S K-edge XANES, measured simultaneously in total electron (TEY) and partial fluorescence yield (PFY) modes, have been applied to study near-surface regions of natural polycrystalline pyrite FeS{sub 2} and pyrrhotite Fe{sub 1−x}S before and after etching treatments in an acidic ferric chloride solution. It was found that the following near-surface regions are formed owing to the preferential release of iron from oxidized metal sulfide lattices: (i) a thin, no more than 1–4 nm in depth, outer layer containing polysulfide species, (ii) a layer exhibiting less pronounced stoichiometry deviations and low, if any, concentrations of polysulfide, the composition and dimensions of which vary for pyrite and pyrrhotite and depend on the chemical treatment, and (iii) an extended almost stoichiometric underlayer yielding modified TEY XANES spectra, probably, due to a higher content of defects. We suggest that the extended layered structure should heavily affect the near-surface electronic properties, and processes involving the surface and interfacial charge transfer.

  7. Size and surface functionalization of iron oxide nanoparticles influence the composition and dynamic nature of their protein corona.

    Science.gov (United States)

    Ashby, Jonathan; Pan, Songqin; Zhong, Wenwan

    2014-09-10

    Nanoparticles (NPs) adsorb proteins when in the biological matrix, and the resulted protein corona could affect NP-cell interactions. The corona has a dynamic nature with the adsorbed proteins constantly exchanging with the free proteins in the matrix at various rates. The rapidly exchanging proteins compose the soft corona, which responds more dynamically to environment changes than the hard corona established by the ones with slow exchange rates. In the present study, the corona formed on the superparamagnetic iron oxide NPs (SPIONs) in human serum was studied by flow field-flow fractionation and ultracentrifugation, which rapidly differentiated the corona proteins based on their exchange rates. By varying the surface hydrophobicity of the SPIONs with a core size around 10 nm, we found out that, the more hydrophobic surface ligand attracted proteins with higher surface hydrophobicity and formed a more dynamic corona with a larger portion of the involved proteins with fast exchange rates. Increasing the core diameter of the SPIONs but keeping the surface ligand the same could also result in a more dynamic corona. A brief investigation of the effect on the cellular uptake of SPIONs using one selected corona protein, transferrin, was conducted. The result showed that, only the stably bound transferrin could significantly enhance cellular uptake, while transferrin bound in a dynamic nature had negligible impact. Our study has led to a better understanding of the relationship between the particle properties and the dynamic nature of the corona, which can help with design of nanomaterials with higher biocompatibility and higher efficacy in biosystems for biomedical applications.

  8. The effect of some fluids on surface oxidation and amount of released iron of stainless steel endodontic files.

    Science.gov (United States)

    Saghiri, Mohammad Ali; García-Godoy, Franklin; Lotfi, Mehrdad; Mehrvazfar, Peyman; Aminsobhani, Mohsen; Rezaie, Samad; Asgar, Kamal

    2012-01-01

    Endodontic files come in contact with blood, infected pulp tissue, and irrigating solutions during root canal therapy. Some instruments such as stereomicroscopy and scanning electron microscopy are used to observe corrosion of endodontic files which are complicated and dependent on preparation methods. Having knowledge of the corrosion and ion release of endodontic files can help in drawing firm deductions as to which files would perform better in the clinical scenario. Therefore, we have used energy dispersive X-ray analysis and an atomic absorption spectrophotometer to track oxygen on the surface and iron in the exposed media to observe the oxidative rate of the media. In this study, corrosion by blood was higher than other biological fluids, but less than with sodium hypochlorite (NaOCl). Observations of energy dispersive X-ray analysis and atomic absorption spectrophotometer results demonstrated that after exposure the amount of oxygen on the surface and surrounding areas increased. Therefore, the files should be rinsed as soon as possible during and after use to hinder the oxidation rate, but blood may produce a different behavior and it might be considered as a decreased risk of broken stainless steel files remaining in the root canal after treatment.

  9. Effects of bionic units on the fatigue wear of gray cast iron surface with different shapes and distributions

    Science.gov (United States)

    Chen, Zhi-kai; Lu, Shu-chao; Song, Xi-bin; Zhang, Haifeng; Yang, Wan-shi; Zhou, Hong

    2015-03-01

    To improve the fatigue wear resistance of gray cast iron (GCI), GCI samples were modified by a laser to imitate the unique structure of some soil animals alternating between soft and hard phases; the hard phase resists the deformation and the soft phase releases the deformation. Using the self-controlled fatigue wear test method, the fatigue wear behaviors of treated and untreated samples were investigated and compared experimentally. The results show that the bionic non-smooth surface obtains a beneficial effect on improving the fatigue wear resistance of a sample, and the fatigue wear resistance of the bionic sample assembled with reticulate units (60°+0°), whose mass loss was reduced by 62%, was superior to the others. Meanwhile, a finite element (FE) was used to simulate the compression and the distributions of strain and stress on the non-smooth surface was inferred. From these results, we understood that the functions of the bionic unit such as reducing strain and stress, and also obstructing the closure and propagation of cracks were the main reasons for improving the fatigue wear property of GCI.

  10. Solvent-surface interactions control the phase structure in laser-generated iron-gold core-shell nanoparticles

    Science.gov (United States)

    Wagener, Philipp; Jakobi, Jurij; Rehbock, Christoph; Chakravadhanula, Venkata Sai Kiran; Thede, Claas; Wiedwald, Ulf; Bartsch, Mathias; Kienle, Lorenz; Barcikowski, Stephan

    2016-03-01

    This work highlights a strategy for the one-step synthesis of FeAu nanoparticles by the pulsed laser ablation of alloy targets in the presence of different solvents. This method allows particle generation without the use of additional chemicals; hence, solvent-metal interactions could be studied without cross effects from organic surface ligands. A detailed analysis of generated particles via transmission electron microscopy in combination with EDX elemental mapping could conclusively verify that the nature of the used solvent governs the internal phase structure of the formed nanoparticles. In the presence of acetone or methyl methacrylate, a gold shell covering a non-oxidized iron core was formed, whereas in aqueous media, an Au core with an Fe3O4 shell was generated. This core-shell morphology was the predominant species found in >90% of the examined nanoparticles. These findings indicate that fundamental chemical interactions between the nanoparticle surface and the solvent significantly contribute to phase segregation and elemental distribution in FeAu nanoparticles. A consecutive analysis of resulting Fe@Au core-shell nanoparticles revealed outstanding oxidation resistance and fair magnetic and optical properties. In particular, the combination of these features with high stability magnetism and plasmonics may create new opportunities for this hybrid material in imaging applications.

  11. Effects of Iron-Oxide Nanoparticle Surface Chemistry on Uptake Kinetics and Cytotoxicity in CHO-K1 Cells

    Directory of Open Access Journals (Sweden)

    Camille C. Hanot

    2015-12-01

    Full Text Available Superparamagnetic iron-oxide nanoparticles (SPIONs show great promise for multiple applications in biomedicine. While a number of studies have examined their safety profile, the toxicity of these particles on reproductive organs remains uncertain. The goal of this study was to evaluate the cytotoxicity of starch-coated, aminated, and PEGylated SPIONs on a cell line derived from Chinese Hamster ovaries (CHO-K1 cells. We evaluated the effect of particle diameter (50 and 100 nm and polyethylene glycol (PEG chain length (2k, 5k and 20k Da on the cytotoxicity of SPIONs by investigating cell viability using the tetrazolium dye 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT and sulforhodamine B (SRB assays. The kinetics and extent of SPION uptake by CHO-K1 cells was also studied, as well as the resulting generation of intracellular reactive oxygen species (ROS. Cell toxicity profiles of SPIONs correlated strongly with their cellular uptake kinetics, which was strongly dependent on surface properties of the particles. PEGylation caused a decrease in both uptake and cytotoxicity compared to aminated SPIONs. Interestingly, 2k Da PEG-modifed SPIONs displayed the lowest cellular uptake and cytotoxicity among all studied particles. These results emphasize the importance of surface coatings when engineering nanoparticles for biomedical applications.

  12. Contribution of coated humic acids calculated through their surface coverage on nano iron oxides for ofloxacin and norfloxacin sorption.

    Science.gov (United States)

    Peng, Hongbo; Liang, Ni; Li, Hao; Chen, Fangyuan; Zhang, Di; Pan, Bo; Xing, Baoshan

    2015-09-01

    Sorption of organic contaminants on organo-mineral complexes has been investigated extensively, but the sorption contribution of mineral particles was not properly addressed before calculating KOC, especially for ionic organic contaminants. We measured the surface coverage of a humic acid (HA) on nano iron oxides (n-Fe2O3) in a series of synthesized organo-mineral complexes. The contribution of the coated HA to ofloxacin (OFL) and norfloxacin (NOR) sorption in HA-n-Fe2O3 complexes was over 80% of the total sorption with the surface coverage of 36% and fOC of 1.6%. All the coated HA showed higher sorption to NOR and OFL in comparison to the original HA, suggesting HA fractionation and/or physical re-conformation during organo-mineral complex formation. The decreased KOC with multilayer coating may suggest the importance of site-specific interactions for OFL sorption, while the increased KOC with multilayer coating may suggest the importance of partitioning in hydrophobic region for NOR sorption. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Determination of sea surface temperatures from microwave and IR data

    Science.gov (United States)

    Rangaswamy, S.; Grover, J.

    1982-01-01

    Microwave measurements from the Nimbus 7 SMMR were used to derive the atmospheric precipitable water, which was then used to obtain the atmospheric correction for use with AVHRR thermal IR measurements to obtain sea surface temperature (SST). The resulting SST's were compared with the NOAA operational sea surface temperature measurements, and the two sets of measurements were found to be in reasonable agreement. The average residuals between the two sets of measurements was 0.15 K with the NOAA operational SST's being slightly greater.

  14. Iron oxidation kinetics and phosphate immobilization along the flow-path from groundwater into surface water.

    NARCIS (Netherlands)

    Grift, van der B.; Rozemeijer, J.C.; Griffioen, J.; Velde, van der Y.

    2014-01-01

    The retention of phosphorus in surface waters though co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and 5 P immobilization along the flow-path fro

  15. Iron oxidation kinetics and phosphate immobilization along the flow-path from groundwater into surface water

    NARCIS (Netherlands)

    van der Grift, B.; Rozemeijer, J. C.; Griffioen, J.; van der Velde, Y.

    2014-01-01

    The retention of phosphorus in surface waters though co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from

  16. Surface Functionalization of Epoxy-Resist- Based Microcantilevers with Iron Oxide Nanocrystals

    DEFF Research Database (Denmark)

    Ingrosso, Chiara; Sardella, E.; Keller, Stephan Sylvest

    2010-01-01

    A functionalization procedure is integrated in the fabrication of micromechanical SU-8 cantilevers in order to chemically bind organic-capped Fe2O3 NCs at the photoresist surface, under visible light, ambient atmosp here and room temperature. The achieved highly interconnected NC multilayer netwo...... is demonstrated an active layer for real-time detection of acetone vapor molecules....

  17. Evidence for three-dimensional Fermi-surface topology of the layered electron-doped iron superconductor Ba(Fe1 xCox)2As2

    Energy Technology Data Exchange (ETDEWEB)

    Vilmercati, P. [University of Tennessee, Knoxville (UTK); Fedorov, A. V. [Lawrence Berkeley National Laboratory (LBNL); Vobornik, I. [TASC National Laboratory, Trieste, Italy; Manju, U. [TASC National Laboratory, Trieste, Italy; Panaccione, G. [TASC National Laboratory, Trieste, Italy; Goldoni, A. [Sincrotrone Trieste, Basovizza, Italy; Safa-Sefat, Athena [ORNL; McGuire, Michael A [ORNL; Sales, Brian C [ORNL; Jin, Rongying [ORNL; Mandrus, David [ORNL; Singh, David J [ORNL; Mannella, Norman [ORNL

    2009-01-01

    The electronic structure of electron doped iron-arsenide superconductors Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} has been measured with Angle Resolved Photoemission Spectroscopy. The data reveal a marked photon energy dependence of points in momentum space where the bands cross the Fermi energy, a distinctive and direct signature of three-dimensionality in the Fermi surface topology. By providing a unique example of high temperature superconductivity hosted in layered compounds with three-dimensional electronic structure, these findings suggest that the iron-arsenides are unique materials, quite different from the cuprates high temperature superconductors.

  18. Surface versus Edge-Based Determinants of Visual Recognition.

    Science.gov (United States)

    Biederman, Irving; Ju, Ginny

    1988-01-01

    The latency at which objects could be identified by 126 subjects was compared through line drawings (edge-based) or color photography (surface depiction). The line drawing was identified about as quickly as the photograph; primal access to a mental representation of an object can be modeled from an edge-based description. (SLD)

  19. Determining Land-Surface Parameters from the ERS Wind Scatterometer

    NARCIS (Netherlands)

    Woodhouse, I.H.; Hoekman, D.H.

    2000-01-01

    The ERS-1 wind scatterometer (WSC) has a resolution cell of about 50 km but provides a high repetition rate (less than four days) and makes measurements at multiple incidence angles. In order to retrieve quantitative geophysical parameters over land surfaces using this instrument, a method is presen

  20. Investigations of the influence of vapour phase inhibitors on the surface charge of iron oxide particles by zeta-potential measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kuenzelmann, U.; Reinhard, G. (Technische Univ., Dresden (German Democratic Republic). Sektion Chemie); Jacobasch, H.J. (Akademie der Wissenschaften der DDR, Dresden. Inst. fuer Technologie der Fasern (German Democratic Republic))

    1989-12-01

    Adsorbability of the vapour phase inhibitor dicyclohexylammonium nitrite (Dichan) and its ionic constituents present in aqueous media were investigated by means of zeta-potential measurements in 10{sup -3} M KCl solution in dependence on the pH-value using particles of various iron oxides and oxide hydroxides. It was pointed out, that the interactions between Dichan and iron oxides result in a negativation of the zeta-potential and in a displacement of the isoelectric point of the particles surface (IEPS) due to specific adsorption of anions. By dicyclohexylamine in the primary solution, the zeta-potential of iron oxides is hardly influenced, even when the saturation concentration is established. As nitrite changes the chemical surface properties when concentrations considerably higher than those indicated for Dichan are achieved, a synergism is assumed to be present because of the Dichan's high adsorbability at oxidic iron compounds. This effect probable consist in the promotion of the specific adsorption of nitrite ions at the oxide surface by the amine component. (orig.).

  1. Deferasirox, deferiprone and desferrioxamine treatment in thalassemia major patients: cardiac iron and function comparison determined by quantitative magnetic resonance imaging

    National Research Council Canada - National Science Library

    Alessia Pepe; Antonella Meloni; Marcello Capra; Paolo Cianciulli; Luciano Prossomariti; Cristina Malaventura; Maria Caterina Putti; Alma Lippi; Maria Antonietta Romeo; Maria Grazia Bisconte; Aldo Filosa; Vincenzo Caruso; Antonella Quarta; Lorella Pitrolo; Massimiliano Missere; Massimo Midiri; Giuseppe Rossi; Vincenzo Positano; Massimo Lombardi; Aurelio Maggio

    2011-01-01

    .... Our study aimed to compare the effectiveness of deferasirox, deferiprone and desferrioxamine on myocardial and liver iron concentrations and bi-ventricular function in thalassemia major patients...

  2. Determination of total iron in water and foods by dispersive liquid-liquid microextraction coupled with microvolume UV-vis spectrophotometry.

    Science.gov (United States)

    Peng, Bo; Shen, Yingping; Gao, Zhuantao; Zhou, Min; Ma, Yongjun; Zhao, Shengguo

    2015-06-01

    A novel microvolume UV-vis spectrophotometry method was proposed for the rapid determination of total iron coupling with an efficient pretreatment method known as dispersive liquid-liquid microextraction (DLLME). The basis of the method is a quantitative colorimetric reaction between ferrous iron and 2-(5-bromo-2-pyridylazo)-5-(diethyl amino) phenol (5-Br-PADAP) after the reduction of Fe(III) to Fe(II) by using ascorbic acid as reducing agent. Parameters related to the efficiency of microextraction, such as pH, complexant concentration, the volume ratio of disperser solvent and extraction solvent were discussed and optimized in detail. Under the optimized conditions, the absorbance was in proportion to iron concentration in the range of 5-400μgL(-1) with a correlation coefficient (R) of 0.9993. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.5μgL(-1) and 5.2μgL(-1), respectively. The relative standard deviation (RSD) for samples were 1.37- 4.42% (n=3). Good recoveries of iron were obtained in the range of 95.4-103.2% in food samples, 96.9-103.6% in water samples and 98.8-102.3% in Certified Reference Material. The proposed method was rapid, reliable and high-selective for the determination of total iron in food and water samples.

  3. Simultaneous direct determination of aluminum, calcium and iron in silicon carbide and silicon nitride powders by slurry-sampling graphite furnace AAS.

    Science.gov (United States)

    Minami, Hirotsugu; Yada, Masako; Yoshida, Tomomi; Zhang, Qiangbin; Inoue, Sadanobu; Atsuya, Ikuo

    2004-03-01

    A fast and accurate analytical method was established for the simultaneous direct determination of aluminum, calcium and iron in silicon carbide and silicon nitride powders by graphite furnace atomic absorption spectrometry using a slurry sampling technique and a Hitachi Model Z-9000 atomic absorption spectrometer. The slurry samples were prepared by the ultrasonication of silicon carbide or silicon nitride powders with 0.1 M nitric acid. Calibration curves were prepared by using a mixed standard solution containing aluminum, calcium, iron and 0.1 M nitric acid. The analytical results of the proposed method for aluminum, calcium and iron in silicon carbide and silicon nitride reference materials were in good agreement with the reference values. The detection limits for aluminum, calcium and iron were 0.6 microg/g, 0.15 microg/g and 2.5 microg/g, respectively, in solid samples, when 200 mg of powdered samples were suspended in 20 ml of 0.1 M nitric acid and a 10 microl portion of the slurry sample was then measured. The relative standard deviation of the determination of aluminum, calcium and iron was 5 - 33%.

  4. Iron oxidation kinetics and phosphate immobilization along the flow-path from groundwater into surface water

    Directory of Open Access Journals (Sweden)

    B. van der Grift

    2014-06-01

    Full Text Available The retention of phosphorus in surface waters though co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II oxidation and P immobilization along the flow-path from groundwater to surface water in an agricultural experimental catchment of a small lowland river. We physically separated tube drain effluent from groundwater discharge before it entered a ditch in an agricultural field. Through continuous discharge measurements and weekly water quality sampling of groundwater, tube drain water, exfiltrated groundwater, and ditch water, we investigated Fe(II oxidation kinetics and P immobilization processes. The oxidation rate inferred from our field measurements closely agreed with the general rate law for abiotic oxidation of Fe(II by O2. Seasonal changes in climatic conditions affected the Fe(II oxidation process. Lower pH and lower temperatures in winter (compared to summer resulted in low Fe oxidation rates. After exfiltration to the surface water, it took a couple of days to more than one week before complete oxidation of Fe(II is reached. In summer time, Fe oxidation rates were much higher. The Fe concentrations in the exfiltrated groundwater were low, indicating that dissolved Fe(II is completely oxidized prior to inflow into a ditch. While the Fe oxidation rates reduce drastically from summer to winter, P concentrations remained high in the groundwater and an order of magnitude lower in the surface water throughout the year. This study shows very fast immobilisation of dissolved P during the initial stage of the Fe(II oxidation proces which results in P-depleted water before Fe(II is competly depleted. This cannot be explained by surface complexation of phosphate to freshly formed Fe-oxyhydroxides but indicates the formation of Fe(III-phosphate precipitates. The formation of Fe(III-phosphates at redox gradients

  5. Charged group surface accessibility determines micelleplexes formation and cellular interaction

    Science.gov (United States)

    Zhang, Yu; Liu, Yang; Sen, Soumyo; Král, Petr; Gemeinhart, Richard A.

    2015-04-01

    Micelleplexes are a class of nucleic acid carriers that have gained acceptance due to their size, stability, and ability to synergistically carry small molecules. MicroRNAs (miRNAs) are small non-coding RNA gene regulator that is consists of 19-22 nucleotides. Altered expression of miRNAs plays an important role in many human diseases. Using a model 22-nucleotide miRNA sequence, we investigated the interaction between charged groups on the micelle surface and miRNA. The model micelle system was formed from methoxy-poly(ethylene glycol)-b-poly(lactide) (mPEG-PLA) mixed with methoxy-poly(ethylene glycol)-b-poly(lactide)-b-oligoarginine (mPEG-PLA-Rx, x = 8 or 15). Surface properties of the micelles were varied by controlling the oligoarginine block length and conjugation density. Micelles were observed to have a core-shell conformation in the aqueous environment where the PLA block constituted the hydrophobic core, mPEG and oligoarginine formed a hydrophilic corona. Significantly different thermodynamic behaviors were observed during the interaction of single stranded miRNA with micelles of different surface properties, and the resulting micelleplexes mediated substantial cellular association. Depending upon the oligoarginine length and density, micelles exhibited miRNA loading capacity directly related to the presentation of charged groups on the surface. The effect of charged group accessibility of cationic micelle on micelleplex properties provides guidance on future miRNA delivery system design.Micelleplexes are a class of nucleic acid carriers that have gained acceptance due to their size, stability, and ability to synergistically carry small molecules. MicroRNAs (miRNAs) are small non-coding RNA gene regulator that is consists of 19-22 nucleotides. Altered expression of miRNAs plays an important role in many human diseases. Using a model 22-nucleotide miRNA sequence, we investigated the interaction between charged groups on the micelle surface and miRNA. The

  6. Curvature-induced symmetry breaking determines elastic surface patterns

    Science.gov (United States)

    Stoop, Norbert; Lagrange, Romain; Terwagne, Denis; Reis, Pedro M.; Dunkel, Jörn

    2015-03-01

    Symmetry-breaking transitions associated with the buckling and folding of curved multilayered surfaces—which are common to a wide range of systems and processes such as embryogenesis, tissue differentiation and structure formation in heterogeneous thin films or on planetary surfaces—have been characterized experimentally. Yet owing to the nonlinearity of the underlying stretching and bending forces, the transitions cannot be reliably predicted by current theoretical models. Here, we report a generalized Swift-Hohenberg theory that describes wrinkling morphology and pattern selection in curved elastic bilayer materials. By testing the theory against experiments on spherically shaped surfaces, we find quantitative agreement with analytical predictions for the critical curves separating labyrinth, hybrid and hexagonal phases. Furthermore, a comparison to earlier experiments suggests that the theory is universally applicable to macroscopic and microscopic systems. Our approach builds on general differential-geometry principles and can thus be extended to arbitrarily shaped surfaces.

  7. Surface Free Energy Determination of APEX Photosensitive Glass

    Directory of Open Access Journals (Sweden)

    William R. Gaillard

    2016-02-01

    Full Text Available Surface free energy (SFE plays an important role in microfluidic device operation. Photosensitive glasses such as APEX offer numerous advantages over traditional glasses for microfluidics, yet the SFE for APEX has not been previously reported. We calculate SFE with the Owens/Wendt geometric method by using contact angles measured with the Sessile drop technique. While the total SFE for APEX is found to be similar to traditional microstructurable glasses, the polar component is lower, which is likely attributable to composition. The SFE was modified at each stage of device fabrication, but the SFE of the stock and fully processed glass was found to be approximately the same at a value of 51 mJ·m−2. APEX exhibited inconsistent wetting behavior attributable to an inhomogeneous surface chemical composition. Means to produce more consistent wetting of photosensitive glass for microfluidic applications are discussed.

  8. Determination of Surface Stress Distributions in Steel Using Laser-Generated Surface Acoustic Waves

    Science.gov (United States)

    Shi; Yifei; Ni; Chenyin; Shen; Zhonghua; Ni; Xiaowu; Lu; Jian

    2008-05-01

    High frequency surface acoustic waves (SAWs) are excited by a pulsed laser and detected by a specially designed poly(vinylidene fluoride) (PVDF) transducer to investigate surface stress distribution. Two kinds of stressed surfaces are examined experimentally. One is a steel plate elastically deformed under simple bending forces, where the surface stress varies slowly. The other is a welded steel plate for which the surface stress varies very rapidly within a small area near the welding seam. Applying a new signal processing method developed from correlation technique, the velocity distribution of the SAWs, which reflects the stress distribution, is obtained in these two samples with high resolution.

  9. Surface Free Energy Determination of APEX Photosensitive Glass

    OpenAIRE

    William R. Gaillard; Emanuel Waddell; Williams, John D.

    2016-01-01

    Surface free energy (SFE) plays an important role in microfluidic device operation. Photosensitive glasses such as APEX offer numerous advantages over traditional glasses for microfluidics, yet the SFE for APEX has not been previously reported. We calculate SFE with the Owens/Wendt geometric method by using contact angles measured with the Sessile drop technique. While the total SFE for APEX is found to be similar to traditional microstructurable glasses, the polar component is lower, which i...

  10. An accurate determination of the surface energy of solid selenium

    Science.gov (United States)

    Guisbiers, G.; Arscott, S.; Snyders, R.

    2012-12-01

    Selenium is currently a key element for developing nano and micro-technologies. Nevertheless, the surface energy of solid selenium (γSe) reported in the literature is still questionable. In this work, we have measured γSe = 0.291 ± 0.025 J/m2 at 293 K using the sessile drop technique with different probe liquids, namely ethylene glycol, de-ionized water, mercury, and gallium. This value is in excellent agreement with theoretical predictions.

  11. 蔗糖铁中2价铁含量测定的极谱电化学研究%Investigation on Iron (H) Determination and Electrochemical Behavior of Iron-Sucrose Complex by Pulse Polargraphy

    Institute of Scientific and Technical Information of China (English)

    方文; 花传政; 汤传飞; 熊守军

    2015-01-01

    对极谱法测定蔗糖铁中2价铁含量的理想和实际物理模型分别进行了讨论,明确了蔗糖铁板谱行为的非理想特征.通过研究发现了影响测定结果的重要参数包括脉冲电压振幅△E,极谱脉冲时间δ和温度T,通过详细试验研究明确了这些参数的具体影响规律.最后,对美国药典中规定的蔗糖铁注射液中2价铁含量测试方法的科学性和合理性进行了分析和探讨,并就新测试方法给出了建议.%Iron (Ⅱ) determination and electrochemical behavior of iron-sucrose complex by pulse polargraphy are theoretical analyzed.The influence of pulse amplitude of voltage pulse △E,pulse time δ and temperature T on height and potential of the first and second polarographic peak is studied with the single factor method.It was found that these three factors had significant influence on the electrochemical behavior of iron-sucrose in pulse polargraphy.And the USP method for the determination of iron(Ⅱ) content in iron sucrose injection is discussed in details.Based on the research results in this paper,some advices for improving the analyzing method given by USP are suggested.

  12. Ultraviolet spectrophotometric method for the determination of iron content in iron folic acid tablets%分光光度法测定铁质叶酸片中铁元素的含量

    Institute of Scientific and Technical Information of China (English)

    秦瑜丽

    2013-01-01

    A method for the determination of iron content in health food tablets by ultraviolet spectrophotometry was established. Use 50% of the hydrochloric acid solution and 10% of hydroxylamine hydrochloride processing samples to make all the iron in samples change into Fe2+. Fe2+ can react with 0. 15% of the phenanthroline solution to form a stable orange red compound. Then all the iron can be deteminated by spectrophotometric method on 511 nm. Results: Fe2+ was good linear over the range 0. 022 4~0. 112 0 mg/mL, the average recovery of Fe2+ was 99. 2%, and RSD was 1% (n=6). This method is simple,stable,precise and accurate. So this study can be used in determination of iron content, in iron folic acid tablets.%建立测定铁质叶酸片中铁含量的方法.用1∶1的盐酸溶液和10%的盐酸羟胺处理样品,使样品中的铁全部转化成Fe2+,Fe2+与0.15%的邻菲罗啉显色剂络合生成稳定的橙红色化合物,按分光光度法,在511 nm处测定吸光度.结果表明,铁离子浓度在0.022 4~0.112 0 mg/mL范围内呈现良好线性.平均回收率为99.2%.RSD为1%(n=6).该方法操作简单,样品前处理简便,结果稳定、精确,适用范围广,可用于铁质叶酸片中铁元素含量的测定.

  13. Determining the size of nanoparticles in the example of magnetic iron oxide core-shell systems

    Science.gov (United States)

    Jarzębski, Maciej; Kościński, Mikołaj; Białopiotrowicz, Tomasz

    2017-08-01

    The size of nanoparticles is one of the most important factors for their possible applications. Various techniques for the nanoparticle size characterization are available. In this paper selected techniques will be considered base on the prepared core-shell magnetite nanoparticles. Magnetite is one of the most investigated and developed magnetic material. It shows interesting magnetic properties which can be used for biomedical applications, such as drug delivery, hypothermia and also as a contrast agent. To reduce the toxic effects of Fe3O4, magnetic core was covered by dextran and gelatin. Moreover, the shell was doped by fluorescent dye for confocal microscopy investigation. The main investigation focused on the methods for particles size determination of modified magnetite nanoparticles prepared with different techniques. The size distribution were obtained by nanoparticle tracking analysis, dynamic light scattering and transmission electron microscopy. Furthermore, fluorescent correlation spectroscopy (FCS) and confocal microscopy were used to compare the results for particle size determination of core-shell systems.

  14. Benefits and harms of iron supplementation in iron-deficient and iron-sufficient children.

    Science.gov (United States)

    Domellöf, Magnus

    2010-01-01

    Due to high iron requirements, young children are at risk for iron deficiency anemia. Iron supplements are therefore often recommended, especially since iron deficiency anemia in children is associated with poor neurodevelopment. However, in contrast to most other nutrients, excess iron cannot be excreted by the human body and it has recently been suggested that excessive iron supplementation of young children may have adverse effects on growth, risk of infections, and even on cognitive development. Recent studies support that iron supplements are beneficial in iron-deficient children but there is a risk of adverse effects in those who are iron replete. In populations with a low prevalence of iron deficiency, general supplementation should therefore be avoided. Iron-fortified foods can still be generally recommended since they seem to be safer than medicinal iron supplements, but the level of iron fortification should be limited. General iron supplementation is recommended in areas with a high prevalence of iron deficiency, with the exception of malarious areas where a cautious supplementation approach needs to be adopted, based either on screening or a combination of iron supplements and infection control measures. More studies are urgently needed to better determine the risks and benefits of iron supplementation and iron-fortified foods given to iron-deficient and iron-sufficient children.

  15. Determination of the local chemistry of iron in inorganic and organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Calvert, Clair C. [LEMAS Centre, Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom)]. E-mail: c.c.calvert@sheffield.ac.uk; Brown, Andy [LEMAS Centre, Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Brydson, Rik [LEMAS Centre, Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2005-05-15

    The systematic EELS analysis of a series of naturally occurring, synthetic and biological samples has provided a framework from which Fe valence of unknown materials can be determined and the relative ratios of the valences present can be calculated. The quantification of the relative ratios of Fe{sup 3+}/Fe{sup 2+} is possible via the fitting of Gaussian or Voigt (with 89.3% Gaussian contribution) line profiles to the Fe L{sub 3}-edge. The ratio of Fe{sup 3+}/{sigma}Fe is determined from the areas under the fitted peaks. The method is robust and has an error in the range of <10% on Fe{sup 3+}/{sigma}Fe for samples with >2 atom% Fe. We present applications of this method including the investigation of polaron hopping in calcic amphibole, the quantification of Fe{sup 3+}/{sigma}Fe in clay minerals from deep water sediments, quantification of Fe valence in human liver tissue and the determination of Fe valence in airborne particulate matter.

  16. The nanophase iron mineral(s) in Mars soil

    Science.gov (United States)

    Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.

    1993-01-01

    A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism

  17. Severity of iron overload of proband determines serum ferritin levels in families with HFE-related hemochromatosis : The HEmochromatosis FAmily Study

    NARCIS (Netherlands)

    Jacobs, Esther M. G.; Hendriks, Jan C. M.; van Deursen, Cees Th. B. M.; Kreeftenberg, Herman G.; de Vries, Richard A.; Marx, Joannes J. M.; Stalenhoef, Anton F. H.; Verbeek, Andre L. M.; Swinkels, Dorine W.

    2009-01-01

    Background/Aims: In families of patients with clinically detected hereditary hemochromatosis (HH) early screening has been suggested to prevent morbidity and mortality. Here, we aim to identify determinants for iron overload in first-degree family members of C282Y homozygous probands with clinically

  18. Severity of iron overload of proband determines serum ferritin levels in families with HFE-related hemochromatosis: the HEmochromatosis FAmily Study.

    NARCIS (Netherlands)

    Jacobs, E.M.G.; Hendriks, J.C.M.; Deursen, C.T. van; Kreeftenberg, H.G.; Vries, R.A. de; Marx, J.J.M.; Stalenhoef, A.F.H.; Verbeek, A.L.M.; Swinkels, D.W.

    2009-01-01

    BACKGROUND/AIMS: In families of patients with clinically detected hereditary hemochromatosis (HH) early screening has been suggested to prevent morbidity and mortality. Here, we aim to identify determinants for iron overload in first-degree family members of C282Y homozygous probands with clinically

  19. Severity of iron overload of proband determines serum ferritin levels in families with HFE-related hemochromatosis : The HEmochromatosis FAmily Study

    NARCIS (Netherlands)

    Jacobs, Esther M. G.; Hendriks, Jan C. M.; van Deursen, Cees Th. B. M.; Kreeftenberg, Herman G.; de Vries, Richard A.; Marx, Joannes J. M.; Stalenhoef, Anton F. H.; Verbeek, Andre L. M.; Swinkels, Dorine W.

    Background/Aims: In families of patients with clinically detected hereditary hemochromatosis (HH) early screening has been suggested to prevent morbidity and mortality. Here, we aim to identify determinants for iron overload in first-degree family members of C282Y homozygous probands with clinically

  20. Determination of Iron in Water Solution by Time-Resolved Femtosecond Laser-Induced Breakdown Spectroscopy

    Science.gov (United States)

    Sergey, S. Golik; Alexey, A. Ilyin; Michael, Yu. Babiy; Yulia, S. Biryukova; Vladimir, V. Lisitsa; Oleg, A. Bukin

    2015-11-01

    The influence of the energy of femtosecond laser pulses on the intensity of Fe I (371.99 nm) emission line and the continuous spectrum of the plasma generated on the surface of Fe3+ water solution by a Ti: sapphire laser radiation with pulse duration laser pulse energy. It is found that an increase of laser pulse energy insignificantly affects on LOD in the time-resolved LIBS and leads to a slight improvement of the limit of detection. supported by the Russian Science Foundation (agreement #14-50-00034) (measurements of limit of detection), Russian Foundation for Basic Research (NK 15-32-20878/15) obtained in the frame of “Organization of Scientific Research” in the Far Eastern Federal University supported by Ministry of Education and Science of Russian Federation

  1. Spatially resolved (semi)quantitative determination of iron (Fe) in plants by means of synchrotron micro X-ray fluorescence.

    Science.gov (United States)

    Terzano, Roberto; Alfeld, Matthias; Janssens, Koen; Vekemans, Bart; Schoonjans, Tom; Vincze, Laszlo; Tomasi, Nicola; Pinton, Roberto; Cesco, Stefano

    2013-04-01

    Iron (Fe) is an essential element for plant growth and development; hence determining Fe distribution and concentration inside plant organs at the microscopic level is of great relevance to better understand its metabolism and bioavailability through the food chain. Among the available microanalytical techniques, synchrotron μ-XRF methods can provide a powerful and versatile array of analytical tools to study Fe distribution within plant samples. In the last years, the implementation of new algorithms and detection technologies has opened the way to more accurate (semi)quantitative analyses of complex matrices like plant materials. In this paper, for the first time the distribution of Fe within tomato roots has been imaged and quantified by means of confocal μ-XRF and exploiting a recently developed fundamental parameter-based algorithm. With this approach, Fe concentrations ranging from few hundreds of ppb to several hundreds of ppm can be determined at the microscopic level without cutting sections. Furthermore, Fe (semi)quantitative distribution maps were obtained for the first time by using two opposing detectors to collect simultaneously the XRF radiation emerging from both sides of an intact cucumber leaf.

  2. Research on Laser Micro Polishing of SLS Technology Sintered Iron-Based Powder Surface

    Directory of Open Access Journals (Sweden)

    Gerda Vaitkūnaitė

    2015-03-01

    Full Text Available The article analyzes laser micro polishing of 1.2083 steel samples produced applying selective laser sintering (SLS method. The study has evaluated the distribution of the shape, size and temperature of the laser beam treated area in the surface layer of sintered and laser polished samples. Experimental tests have shown the impact of the technical parameters of laser micro polishing on the width and hardness of the impact zone of the treated sample. The microstructure analysis of laser treated and untreated areas of the material has been made.

  3. Surface adsorption of organoarsenic roxarsone and arsanilic acid on iron and aluminum oxides.

    Science.gov (United States)

    Chen, Wan-Ru; Huang, Ching-Hua

    2012-08-15

    Aromatic organoarsenicals roxarsone (ROX) and p-arsanilic acid (ASA) are common feed additives for livestock and could be released into the environment via animal manure and agricultural runoff. To evaluate their environmental fate, the adsorption behavior of ROX and ASA was investigated with two common soil metal oxides, goethite (FeOOH) and aluminum oxide (Al(2)O(3)), under different reactant loading, water pH and competing ion conditions. ROX and ASA exhibit essentially identical adsorption characteristics. FeOOH and Al(2)O(3) exhibit similar adsorption trends for both organoarsenicals; however, the adsorption efficiency on the surface site basis was about three times lower for Al(2)O(3) than for FeOOH. The adsorption reaction is favorable at neutral and acidic pH. Phosphate and natural organic matter significantly interfere with aromatic arsenical adsorption on both metal oxides, whereas sulfate and nitrate do not. Pre-adsorbed aromatic arsenicals can be quickly but not completely displaced by phosphate, indicating that ion exchange is not the only mechanism governing the adsorption process. The adsorption envelope was successfully modeled by a diffuse double layer surface complexation model, identifying the critical role of di-anionic organoarsenic species in the adsorption. Results of this research can help predict and control the mobility of aromatic arsenicals in the environment.

  4. Mapping Electrochemical Heterogeneity at Iron Oxide Surfaces: A Local Electrochemical Impedance Study.

    Science.gov (United States)

    Lucas, Marie; Boily, Jean-François

    2015-12-22

    Alternating current scanning electrochemical microscopy (AC-SECM) was used for the first time to map key electrochemical attributes of oriented hematite (α-Fe2O3) single crystal surfaces at the micron-scale. Localized electrochemical impedance spectra (LEIS) of the (001) and (012) faces provided insight into the spatial variations of local double layer capacitance (C(dl)) and charge transfer resistance (R(ad)). These parameters were extracted by LEIS measurements in the 0.4-8000 Hz range to probe the impedance response generated by the redistribution of water molecules and charge carriers (ions) under an applied AC. These were attributed to local variations in the local conductivity of the sample surfaces. Comparison with global EIS measurements on the same samples uncovered highly comparable frequency-resolved processes, that were broken down into contributions from the bulk hematite, the interface as well as the microelectrode/tip assembly. This work paves the way for new studies aimed at mapping electrochemical processes at the mesoscale on this environmentally and technologically important material.

  5. Determination of uranium, iron, copper, and nickel from ore samples by MEKC using N,N'-ethylene bis(salicylaldimine) as complexing reagent.

    Science.gov (United States)

    Mirza, Muhammed Aslam; Khuhawar, Muhammad Yar; Arain, Rafee

    2008-02-01

    An analytical procedure has been developed for the separation of dioxouranium(VI), iron(III), copper(II), nickel(II), cobalt(II), cobalt(III), palladium(II), and thorium(IV) by MEKC using N,N'-ethylene bis(salicylaldimine) (H(2)SA(2)en) as a complexing reagent with total runtime ore samples indicating its presence within 103-1789 microg/g with RSD within 0.79-1.87%. Likewise copper, nickel, and iron in their combined matrix were also simultaneously determined with RSD 0.4-1.6% (n = 6).

  6. Improved in-situ methods for determining land surface emissivity

    Science.gov (United States)

    Göttsche, Frank; Olesen, Folke; Hulley, Glynn

    2014-05-01

    The accurate validation of LST satellite products, such as the operational LST retrieved by the Land Surface Analysis - Satellite Application Facility (LSA-SAF), requires accurate knowledge of emissivity for the areas observed by the ground radiometers as well as for the area observed by the satellite sensor. Especially over arid regions, the relatively high uncertainty in land surface emissivity (LSE) limits the accuracy with which land surface temperature (LST) can be retrieved from thermal infrared (TIR) radiance measurements. LSE uncertainty affects LST obtained from satellite measurements and in-situ radiance measurements alike. Furthermore, direct comparisons between satellite sensors and ground based sensors are complicated by spatial scale mismatch: ground radiometers usually observe some 10 m2, whereas satellite sensors typically observe between 1 km2 and 100 km2. Therefore, validation sites have to be carefully selected and need to be characterised on the scale of the ground radiometer as well as on the scale of the satellite pixel. The permanent stations near Gobabeb (Namibia; hyper-arid desert climate) and Dahra (Senegal; hot-arid steppe-prairie climate) are two of KIT's four dedicated LST validation stations. Gobabeb station is located on vast and flat gravel plains (several 100 km2), which are mainly covered by coarse gravel, sand, and desiccated grass. The gravel plains are highly homogeneous in space and time, which makes them ideal for validating a broad range of satellite-derived products. Dahra station is located in so called 'tiger bush' and is covered by strongly seasonal grass (95%) and sparse, evergreen trees (dominantly acacia trees) with a background of reddish sand. The strong seasonality is caused by a pronounced rainy season, during which LST retrieval is highly challenging. Outside the rainy season, both sites have relatively large fractions of bare ground and desiccated vegetation: therefore, they are particularly prone to be

  7. Determination of iron absorption and excretion by whole-body counting; Determination de l'absorption et de l'excretion du fer par la methode de comptage global humain

    Energy Technology Data Exchange (ETDEWEB)

    Hollard, D.; Benabid, Y.; Berard, M.; Bonnin, J.; Darnault, J.; Millet, M. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Using a whole-body counter, the authors have studied {sup 59}Fe absorption and loss in 8 normal subjects and in 30 iron deficient patients. Results showed that whole-body counting provided an excellent and simple method for iron retention measurements, obviating many inaccuracies of previous technic. Normal absorption of radio iron with this procedure has ranged from 9 per cent to 20 per cent of the administered tracer in normal subjects, with a mean of 15 per cent. A significant increase in {sup 59}Fe absorption was noted in 21 iron-deficient patients in whom the retention ranged from 40 to 100 per cent. However, 3 iron-deficient patients were found to have low absorption, and their severe iron deficiency could be correlated with this defect in absorption. This method permits also the determination of the rate of iron excretion during the following months and therefore the study of the mechanism of some pathological loss. (authors) [French] L'utilisation de la methode de comptage humain global a permis aux auteurs d'etudier l'absorption et l'excretion du fer-59 chez 8 sujets temoins et 30 sujets hyposideremiques. Les resultats montrent que cette technique simple et directe offre de nombreux avantages sur les methodes employees jusqu'a maintenant pour cette determination. La valeur normale de l'absorption du fer chez les temoins est d'environ 15 pour cent de la dose ingeree. Ce chiffre est tres fortement augmente chez 21 sujets hyposideremiques, pouvant atteindre 100 pour cent de la dose ingeree. Par contre, pour 3 malades, cette absorption est si faible qu'elle suggere une carence par defaut d'absorption. Cette methode permet egalement de suivre l'excretion du fer au cours des mois qui suivent l'examen et de determiner le mecanisme de fuites anormales. (auteurs)

  8. Inverse parameter determination in the development of an optimized lithium iron phosphate - Graphite battery discharge model

    Science.gov (United States)

    Maheshwari, Arpit; Dumitrescu, Mihaela Aneta; Destro, Matteo; Santarelli, Massimo

    2016-03-01

    Battery models are riddled with incongruous values of parameters considered for validation. In this work, thermally coupled electrochemical model of the pouch is developed and discharge tests on a LiFePO4 pouch cell at different discharge rates are used to optimize the LiFePO4 battery model by determining parameters for which there is no consensus in literature. A discussion on parameter determination, selection and comparison with literature values has been made. The electrochemical model is a P2D model, while the thermal model considers heat transfer in 3D. It is seen that even with no phase change considered for LiFePO4 electrode, the model is able to simulate the discharge curves over a wide range of discharge rates with a single set of parameters provided a dependency of the radius of the LiFePO4 electrode on discharge rate. The approach of using a current dependent radius is shown to be equivalent to using a current dependent diffusion coefficient. Both these modelling approaches are a representation of the particle size distribution in the electrode. Additionally, the model has been thermally validated, which increases the confidence level in the selection of values of parameters.

  9. Determination of Nickel, Vanadium and Iron in Crude Oil by Three-Phase Plasma Arc Spectrometry

    Science.gov (United States)

    Ghatass, Zekry F.

    2002-12-01

    Three-phase plasma arc (TPPA) with ultrasonic nebulizer is developed for simultaneous determination of trace elements in crude oil samples. Ultrasonic nebulizer is used instead of pneumatic nebulizer in order to minimize the problems caused by the oil viscosity during the operation. This system was used for determination of some trace elements (V, Ni, and Fe) in a crude oil samples. Methyl isobutyl ketone (MIBK) was used to dilute the oil samples. The TPPA instrument offers several advantages including a low cost power supply with no radio frequency, linear dynamic ranges from 4 to 5 of orders of magnitude, and detection limits (0.121, 0.313 and 0.242 (μg/ml) for Ni, V and Fe respectively. The average concentrations were 31 ± 0.45 (μg/ml) for Ni, 40 ± 0.88 (μg/ml) for V and 8 ± 0.74 (μg/ml) for Fe at Balaaiem fields and 2 ± 0.05 (μg/ml) for Ni, 4.8 ± 0.25 (μg/ml) for V and 2 ± 0.10 (μg/ml) for Fe at Wastern Desert fields.

  10. Surface plasmon resonance immunosensor for cortisol and cortisone determination.

    Science.gov (United States)

    Frasconi, Marco; Mazzarino, Monica; Botrè, Francesco; Mazzei, Franco

    2009-08-01

    In this paper, we present a surface-plasmon-resonance-based immunosensor for the real-time detection of cortisol and cortisone levels in urine and saliva samples. The method proposed here is simple, rapid, economic, sensitive, robust, and reproducible thanks also to the special features of the polycarboxylate-hydrogel-based coatings used for the antibody immobilization. The sensor surface displays a high level of stability during repeated regeneration and affinity reaction cycles. The immunosensor shows high specificity for cortisol and cortisone; furthermore, no significant interferences from other steroids with a similar chemical structure have been observed. The suitability of the hydrogel coating for the prevention of nonspecific binding is also investigated. A good correlation is noticed between the results obtained by the proposed method and the reference liquid chromatography/tandem mass spectrometry method for the analysis of cortisol and cortisone in urine and saliva samples. Standard curves for the detection of cortisol and cortisone in saliva and urine are characterized by a detection limit less than 10 microg l(-1), sufficiently sensitive for both clinical and forensic use.

  11. Iron oxide magnetic nanoparticles with versatile surface functions based on dopamine anchors

    Science.gov (United States)

    Mazur, Mykola; Barras, Alexandre; Kuncser, Victor; Galatanu, Andrei; Zaitzev, Vladimir; Turcheniuk, Kostiantyn V.; Woisel, Patrice; Lyskawa, Joel; Laure, William; Siriwardena, Aloysius; Boukherroub, Rabah; Szunerits, Sabine

    2013-03-01

    The synthesis of multifunctional magnetic nanoparticles (MF-MPs) is one of the most active research areas in advanced materials as their multifunctional surfaces allow conjugation of biological and chemical molecules, thus making it possible to achieve target-specific diagnostic in parallel to therapeutics. We report here a simple strategy to integrate in a one-step reaction several reactive sites onto the particles. The preparation of MF-MPs is based on their simultaneous modification with differently functionalized dopamine derivatives using simple solution chemistry. The formed MF-MPs show comparable magnetic properties to those of naked nanoparticles with almost unaltered particle size of around 25 nm. The different termini, amine, azide and maleimide functions, enable further functionalization of MF-MPs by the grafting-on approach. Michael addition, Cu(i) catalyzed « click » chemistry and amidation reactions are performed on the MF-MPs integrating subsequently 6-(ferrocenyl)-hexanethiol, horseradish peroxidase (HRP) and mannose.

  12. Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II)

    Science.gov (United States)

    Amirbahman, Aria; Kent, Douglas B.; Curtis, Gary P.; Marvin-DiPasquale, Mark C.

    2013-01-01

    Production of elemental mercury, Hg(0), via Hg(II) reduction is an important pathway that should be considered when studying Hg fate in environment. We conducted a kinetic study of abiotic homogeneous and surface-catalyzed Hg(0) production by Fe(II) under dark anoxic conditions. Hg(0) production rate, from initial 50 pM Hg(II) concentration, increased with increasing pH (5.5–8.1) and aqueous Fe(II) concentration (0.1–1 mM). The homogeneous rate was best described by the expression, rhom = khom [FeOH+] [Hg(OH)2]; khom = 7.19 × 10+3 L (mol min)−1. Compared to the homogeneous case, goethite (α-FeOOH) and hematite (α-Fe2O3) increased and γ-alumina (γ-Al2O3) decreased the Hg(0) production rate. Heterogeneous Hg(0) production rates were well described by a model incorporating equilibrium Fe(II) adsorption, rate-limited Hg(II) reduction by dissolved and adsorbed Fe(II), and rate-limited Hg(II) adsorption. Equilibrium Fe(II) adsorption was described using a surface complexation model calibrated with previously published experimental data. The Hg(0) production rate was well described by the expression rhet = khet [>SOFe(II)] [Hg(OH)2], where >SOFe(II) is the total adsorbed Fe(II) concentration; khet values were 5.36 × 10+3, 4.69 × 10+3, and 1.08 × 10+2 L (mol min)−1 for hematite, goethite, and γ-alumina, respectively. Hg(0) production coupled to reduction by Fe(II) may be an important process to consider in ecosystem Hg studies.

  13. 磷素对水稻根表红棕色铁膜的影响及营养效应%Effect of Phosphorus on Reddish Brown Iron Plaque on Root Surface of Rice Seedlings and Their Nutritional Effects

    Institute of Scientific and Technical Information of China (English)

    傅友强; 杨旭健; 吴道铭; 沈宏

    2014-01-01

    红棕色铁膜颜色加深;随着根系溶液中铁浓度的增加,根表DCB-Fe浓度逐渐增加,最大值为36.50 mg·g-1。最后进一步对磷铁比处理形成的根表红棕色铁膜水稻根系和地上部磷、铁吸收量进行测定,研究结果发现,根表红棕色铁膜的加深有利于水稻根系和地上部磷、铁的吸收。【结论】内源磷信号并不能诱导根表红棕色铁膜的形成,仅外源磷缺乏才能诱导根表红棕色铁膜的形成,根表红棕色铁膜的形成与根系周围环境中磷铁比有关,而根表DCB-Fe的形成仅与溶液中铁浓度有关。形成的根表红棕色铁膜在根系周围充当营养库的功能,有利于植物对磷、铁的吸收利用。%Objective]Phosphorus (P) deficiency could significantly induce the formation of reddish brown iron plaque on the surface of rice roots. However, it remains unclear how P induces the formation of reddish brown iron plaque on root surface.[Method] In this study, 24 rice varieties of different origins were used to measure the iron plaque on their root surface. Rice seedlings were firstly cultivated for 21 days hydroponically, and then submitted to P-deficient solution and 0.1 mmol·L-1 Fe2+solution, respectively. The parameters including root length, root surface area, root and shoot dry weight and content of iron plaque were determined after treatments. Based on the above parameters, a rice variety (Tianyou 998) was screened with higher amount of iron plaque. In the following experiments, effects of different nutrient deficiencies (N deficiency, P deficiency, K deficiency, and their interactive treatments, etc.), root-split treatments (root system was divided into two parts, both two parts were treated with P supply treatments, one part was treated with P-deficient treatment, and the other was with P supply treatment, or both two parts were treated with P-deficient treatment) and different P/Fe treatments (1﹕1, 1﹕3, 1﹕5, 1﹕8) on the

  14. Spectrophotometric Determination of Iron(II after Solid Phase Extraction of Its 2,2′ Bipyridine Complex on Silica Gel-Polyethylene Glycol

    Directory of Open Access Journals (Sweden)

    Nahid Pourreza

    2013-01-01

    Full Text Available A new solid phase extraction procedure was developed for preconcentration of iron(II using silica gel-polyethylene glycol (silica-PEG as an adsorbent. The method is based on retention of iron(II as 2,2′ bipyridine complex on silica-PEG. The retained complex is eluted by 1.0 mol L−1 of sulfuric acid-acetone mixture (1:2 and its absorbance is measured at 518 nm, spectrophotometrically. The effects of different parameters such as pH, concentration of the reagent, eluting reagent, sample volume, amount of adsorbent, and interfering ions were investigated. The calibration graph was linear in the range of 1–60 ng mL−1 of iron(II. The limit of detection based on 3Sb was 0.57 ng mL−1 and relative standard deviations (R.S.D for ten replicate measurements of 12 and 42 ng mL−1 of iron(II were 2.4 and 1.7%, respectively. The method was applied to the determination of of iron(II in water, multivitamin tablet, and spinach samples.

  15. Socioeconomic determinants of iron-deficiency anemia among children aged 6 to 59 months in India.

    Science.gov (United States)

    Bharati, Susmita; Pal, Manoranjan; Chakrabarty, Suman; Bharati, Premananda

    2015-03-01

    The extent of anemia and its socioeconomic determinants among the preschool children (6-59 months old) in India have been studied in this article. Relevant data are taken from the third round of the National Family Health Survey. The initial analysis reveals some interesting features. The most affected children are in the age-group of 6 to 23 months. Beyond this age a decreasing trend is observed up to the age of 48 to 59 months. The highest and the lowest prevalence of anemia have been found to be in the central and the northeast zones, respectively. The vulnerable groups are the children of illiterate parents and those belonging to the poor families in the rural areas. Categorical logistic regression also confirms that status of literacy and wealth of parents have strong negative association with the status of anemia of the children.

  16. Determination of copper, zinc and iron in broncho-alveolar lavages by atomic absorption spectroscopy.

    Science.gov (United States)

    Harlyk, C; Mccourt, J; Bordin, G; Rodriguez, A R; van der Eeckhout, A

    1997-11-01

    Concentrations of Zn, Cu and Fe were measured in 157 broncho-alveolar lavages (BAL), before and after centrifugation, collected at the Leuven University Hospital (Belgium). Zn was measured by flame-atomic absorption spectroscopy, using direct calibration, while Cu and Fe were determined by electrothermal atomic absorption spectroscopy, using the method of standard additions. For Fe only 56 samples were measured. Most of the studied elements are present in the liquid phase (supernatant). About 90% of Cu concentrations lie between 0 and 15 micrograms/kg, while 90% of Zn concentrations are lower than 230 micrograms/kg, with 30% between 30 and 70 micrograms/kg, and 50% between 100 and 200 micrograms/kg. There seems to be a reverse relationship between Cu and Zn levels with high Cu going along with low Zn and vice versa.

  17. Iron oxide nanoparticles surface coating and cell uptake affect biocompatibility and inflammatory responses of endothelial cells and macrophages

    Science.gov (United States)

    Orlando, Antonina; Colombo, Miriam; Prosperi, Davide; Gregori, Maria; Panariti, Alice; Rivolta, Ilaria; Masserini, Massimo; Cazzaniga, Emanuela

    2015-09-01

    Engineered iron oxide nanoparticles (IONP) offer the possibility of a wide range of medical uses, from clinical imaging to magnetically based hyperthermia for tumor treatment. These applications require their systemic administration in vivo. An important property of nanoparticles is their stability in biological media. For this purpose, a multicomponent nanoconstruct combining high colloidal stability and improved physical properties was synthesized and characterized. IONP were coated with an amphiphilic polymer (PMA), which confers colloidal stability, and were pegylated in order to obtain the nanoconstruct PEG-IONP-PMA. The aim of this study was to utilize cultured human endothelial cells (HUVEC) and murine macrophages, taken as model of cells exposed to NP after systemic administration, to assess the biocompatibility of PEG-IONP-PMA (23.1 ± 1.4 nm) or IONP-PMA (15.6 ± 3.4 nm). PEG-IONP-PMA, tested at different concentrations as high as 20 μg mL-1, exhibited no cytotoxicity or inflammatory responses. By contrast, IONP-PMA showed a concentration-dependent increase of cytotoxicity and of TNF-α production by macrophages and NO production by HUVECs. Cell uptake analysis suggested that after PEGylation, IONP were less internalized either by macrophages or by HUVEC. These results suggest that the choice of the polymer and the chemistry of surface functionalization are a crucial feature to confer to IONP biocompatibility.

  18. Iron oxide nanoparticles surface coating and cell uptake affect biocompatibility and inflammatory responses of endothelial cells and macrophages

    Energy Technology Data Exchange (ETDEWEB)

    Orlando, Antonina [University of Milano-Bicocca, Department of Health Sciences (Italy); Colombo, Miriam; Prosperi, Davide [University of Milano-Bicocca, Department of Biotechnology and Biosciences (Italy); Gregori, Maria; Panariti, Alice; Rivolta, Ilaria; Masserini, Massimo; Cazzaniga, Emanuela, E-mail: emanuela.cazzaniga@unimib.it [University of Milano-Bicocca, Department of Health Sciences (Italy)

    2015-09-15

    Engineered iron oxide nanoparticles (IONP) offer the possibility of a wide range of medical uses, from clinical imaging to magnetically based hyperthermia for tumor treatment. These applications require their systemic administration in vivo. An important property of nanoparticles is their stability in biological media. For this purpose, a multicomponent nanoconstruct combining high colloidal stability and improved physical properties was synthesized and characterized. IONP were coated with an amphiphilic polymer (PMA), which confers colloidal stability, and were pegylated in order to obtain the nanoconstruct PEG-IONP-PMA. The aim of this study was to utilize cultured human endothelial cells (HUVEC) and murine macrophages, taken as model of cells exposed to NP after systemic administration, to assess the biocompatibility of PEG-IONP-PMA (23.1 ± 1.4 nm) or IONP-PMA (15.6 ± 3.4 nm). PEG-IONP-PMA, tested at different concentrations as high as 20 μg mL{sup −1}, exhibited no cytotoxicity or inflammatory responses. By contrast, IONP-PMA showed a concentration-dependent increase of cytotoxicity and of TNF-α production by macrophages and NO production by HUVECs. Cell uptake analysis suggested that after PEGylation, IONP were less internalized either by macrophages or by HUVEC. These results suggest that the choice of the polymer and the chemistry of surface functionalization are a crucial feature to confer to IONP biocompatibility.

  19. Experimental Investigation of Erosive Wear on the High Chrome Cast Iron Impeller of Slurry Disposal Pump Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Sunil Kumar

    2012-05-01

    Full Text Available Erosive wear occurs on the impeller and volute casing of the slurry disposal pump due to the impact of the ash particles on the impeller with a high velocity. Due to erosive wear, pump life become very short. The service life of centrifugal pump, handling slurry can be increased by reducing the erosive wear. In the present work, the experimental investigation of erosive wear has been carried out on the high speed slurry erosion tester to understand the effects of the ash concentration in slurry, rotational speed of the pump impeller and ash particle size on erosive wear. The erosive wear behavior of high chrome cast iron was investigated by Response surface methodology (RSM. Analysis of variance (ANOVA was used for statistical analysis and the modeled values for the response were obtained with the help of modeled equation. The result shows that the ash concentration in slurry and kinetic energy of the moving particles highly contributes to erosive wear of pump impeller as compared to the ash particle size.

  20. EXPERIMENTAL INVESTIGATION OF EROSIVE WEAR ON THE HIGH CHROME CAST IRON IMPELLER OF SLURRY DISPOSAL PUMP USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    Jasbir Singh Ratol

    2012-07-01

    Full Text Available Erosive wear occurs on the impeller and volute casing of the slurry disposal pump due to the impact of the ash particles on the impeller with a high velocity. Due to erosive wear, pump life become very short. The service life of centrifugal pump, handling slurry can be increased by reducing the erosive wear. In the present work, the experimental investigation of erosive wear has been carried out on the high speed slurry erosion tester to understand the effects of the ash concentration in slurry, rotational speed of the pump impeller and ash particle size on erosive wear. The erosive wear behaviour of high chrome cast iron was investigated by Response surface methodology (RSM. Analysis of variance (ANOVA was used for statistical analysis and the modeled values for the response were obtained with the help of modeled equation. The result shows that the ash concentration in slurry and kinetic energy of the moving particles highly contributes to erosive wear of pump impeller as compared to the ash particle size.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sahin, Cigdem Arpa, E-mail: carpa@hacettepe.edu.tr [Hacettepe University, Chemistry Department, 06800 Beytepe, Ankara (Turkey); Tokgoez, Ilknur; Bektas, Sema [Hacettepe University, Chemistry Department, 06800 Beytepe, Ankara (Turkey)

    2010-09-15

    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) was added as a surfactant. The micellar solution was heated above 50 {sup o}C and loaded through a column packed with cotton for phase separation. Then the surfactant-rich phase was eluted using 0.05 mol L{sup -1} H{sub 2}SO{sub 4} 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{sup -1}, the limits of quantification (10s) were 2.2 and 1.0 ng mL{sup -1} for iron and copper, respectively. The relative standard deviation (RSD) for ten replicate measurements of 10 ng mL{sup -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.

  2. Determination of copper, lead and iron in water and food samples after column solid phase extraction using 1-phenylthiosemicarbazide on Dowex Optipore L-493 resin.

    Science.gov (United States)

    Yildiz, Ozden; Citak, Demirhan; Tuzen, Mustafa; Soylak, Mustafa

    2011-02-01

    A novel solid phase extraction procedure for determination of copper, lead and iron in natural water and food samples has been established in the presented work. 1-Phenylthiosemicarbazide (1-PTSC) as ligand and Dowex Optipore L-493 resin as adsorbent were used in a mini chromatographic column. Various analytical conditions for the quantitative recoveries of analyte ions including pH, amounts of adsorbent, eluent, sample volume, e