WorldWideScience

Sample records for stage iron oxide

  1. Distribution of iron cations in natural chromites at different stages of oxidation: a {sup 57}Fe Moessbauer investigation

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Tapan; Mitra, Sachinath [Jadavpur Univ., Calcutta (India). Dept. of Geological Sciences; Moon, Hi-Soo [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Geology

    1994-07-01

    {sup 57}Fe Moessbauer spectroscopic investigation of natural chromites from two chromite deposits of India (Sukinda and Byrapur) documents partly inverse spinel structure arising out of oxidation. The spectral fitting was based on allowing a disordering distribution of Fe{sup 2+} and Fe{sup 3+} ions at tetrahedral (A) and octahedral (B) sites. Moessbauer investigation of the samples taken from the physico-chemically distinct two horizons of Sukinda viz. brown ore and grey ores, and Byrapur area revealed three types of iron ion distribution as: Fe{sup 2+}(A), Fe{sup 3+}(A) and Fe{sup 2+}(B) (GC-group); (b)Fe{sup 3+}(A{sub 1}), Fe{sup 3+}(A{sub 2}) and Fe{sup 2+}(B) (BC-2 group), and (c) Fe{sup 3+}(A{sub 1}), Fe{sup 3+}(B) (BC-1 group). The distribution pattern of iron cations at A and B sites was linked to the degree of oxidation. These stages of oxidation could be modelled from normal to inverse form. A model suggesting `electron localisation` at the B-sites makes the intermediate stage. Iron site occupancy determined by Moessbauer spectroscopy of the presently studied samples indicates that these fall under three groups of oxidation stages. An early stage of oxidation is shown by samples of group GC, intermediate stage by group BC-2 and final stage by BC-1 group of chromite samples. The imprint of progressive oxidation manifested by Fe cation site occupancy has been correlated with the Fe{sup 2+}/{Sigma}Fe ratios, obtained for each group of samples. (author). 39 refs., 2 figs., 3 tabs.

  2. Initial Stage of Oxidation of Iron and Steels Heated at High Temperatures Ambient

    Czech Academy of Sciences Publication Activity Database

    Adamaszek, K.; Kučera, Jaroslav

    2001-01-01

    Roč. 7, č. 1 (2001), s. 419-423 ISSN 1335-1532. [International Symposium on Metallography /11./. Stará Lesná, 25.04.2001-27.04.2001] R&D Projects: GA ČR GA106/01/0379; GA ČR GA106/01/0382 Institutional research plan: CEZ:AV0Z2041904 Keywords : iron * steels * oxidation Subject RIV: JG - Metallurgy

  3. 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

  4. Iron oxides photochemical dissolution

    International Nuclear Information System (INIS)

    Blesa, M.A.; Litter, M.I.

    1987-01-01

    This work was intended to study the light irradiation influence of diverse wave-lengths on iron oxides dissolution in aqueous solutions. The objectives of this work were: the exploration of photochemical processes with the aim of its eventual application in: a) decontamination and chemical cleaning under special conditions; b) materials for solar energy conversion. (Author)

  5. Superparamagnetic iron oxides for MRI

    International Nuclear Information System (INIS)

    Weissleder, R.; Reimer, P.

    1993-01-01

    Pharmaceutical iron oxide preparations have been used as MRI contrast agents for a variety of purposes. These agents predominantly decrease T2 relaxation times and therefore cause a decrease in signal intensity of tissues that contain the agent. After intravenous administration, dextran-coated iron oxides typically accumulate in phagocytic cells in liver and spleen. Clinical trials have shown that iron oxide increases lesion/liver and lesion/spleen contrast, that more lesions can be depicted than on plain MRI or CT, and that the size threshold for lesion detection decreases. Decreased uptake of iron oxides in liver has been observed in hepatitis and cirrhosis, potentially allowing the assessment of organ function. More recently a variety of novel, target-specific monocrystalline iron oxides compounds have been used for receptor and immunospecific images. Future development of targeted MRI contrast agents is critical for organ- or tissue-specific quantitative and functional MRI. (orig.)

  6. Superparamagnetic iron oxides for MRI

    Energy Technology Data Exchange (ETDEWEB)

    Weissleder, R [MGH-NMR Center, Dept. of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Reimer, P [MGH-NMR Center, Dept. of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); [Inst. fuer Klinische Radiologie, Zentrale Roentgendiagnostik, Westfaelische-Wilhelms-Univ., Muenster (Germany)

    1993-06-01

    Pharmaceutical iron oxide preparations have been used as MRI contrast agents for a variety of purposes. These agents predominantly decrease T2 relaxation times and therefore cause a decrease in signal intensity of tissues that contain the agent. After intravenous administration, dextran-coated iron oxides typically accumulate in phagocytic cells in liver and spleen. Clinical trials have shown that iron oxide increases lesion/liver and lesion/spleen contrast, that more lesions can be depicted than on plain MRI or CT, and that the size threshold for lesion detection decreases. Decreased uptake of iron oxides in liver has been observed in hepatitis and cirrhosis, potentially allowing the assessment of organ function. More recently a variety of novel, target-specific monocrystalline iron oxides compounds have been used for receptor and immunospecific images. Future development of targeted MRI contrast agents is critical for organ- or tissue-specific quantitative and functional MRI. (orig.)

  7. Molecular magnetic resonance imaging of activated hepatic stellate cells with ultrasmall superparamagnetic iron oxide targeting integrin αvβ3 for staging liver fibrosis in rat model

    Directory of Open Access Journals (Sweden)

    Zhang C

    2016-03-01

    Full Text Available Caiyuan Zhang,1,* Huanhuan Liu,1,* Yanfen Cui,1,* Xiaoming Li,1 Zhongyang Zhang,1 Yong Zhang,2 Dengbin Wang1 1Department of Radiology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, 2MR Advanced Application and Research Center, GE Healthcare China, Shanghai, People’s Republic of China *These authors contributed equally to this work Purpose: To evaluate the expression level of integrin αvβ3 on activated hepatic stellate cells (HSCs at different stages of liver fibrosis induced by carbon tetrachloride (CCl4 in rat model and the feasibility to stage liver fibrosis by using molecular magnetic resonance imaging (MRI with arginine-glycine-aspartic acid (RGD peptide modified ultrasmall superparamagnetic iron oxide nanoparticle (USPIO specifically targeting integrin αvβ3.Materials and methods: All experiments received approval from our Institutional Animal Care and Use Committee. Thirty-six rats were randomly divided into three groups of 12 subjects each, and intraperitoneally injected with CCl4 for either 3, 6, or 9 weeks. Controls (n=10 received pure olive oil. The change in T2* relaxation rate (ΔR2* pre- and postintravenous administration of RGD-USPIO or naked USPIO was measured by 3.0T clinical MRI and compared by one-way analysis of variance or the Student’s t-test. The relationship between expression level of integrin αvβ3 and liver fibrotic degree was evaluated by Spearman’s ranked correlation.Results: Activated HSCs were confirmed to be the main cell types expressing integrin αvβ3 during liver fibrogenesis. The protein level of integrin αv and β3 subunit expressed on activated HSCs was upregulated and correlated well with the progression of liver fibrosis (r=0.954, P<0.001; r=0.931, P<0.001, respectively. After injection of RGD-USPIO, there is significant difference in ΔR2* among rats treated with 0, 3, 6, and 9 weeks of CCl4 (P<0.001. The accumulation of iron particles in fibrotic liver specimen is

  8. 21 CFR 186.1374 - Iron oxides.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Iron oxides. 186.1374 Section 186.1374 Food and... Substances Affirmed as GRAS § 186.1374 Iron oxides. (a) Iron oxides (oxides of iron, CAS Reg. No. 1332-37-2) are undefined mixtures of iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron (III...

  9. 21 CFR 73.2250 - Iron oxides.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including the...

  10. Initial stages of high temperature metal oxidation

    International Nuclear Information System (INIS)

    Yang, C.Y.; O'Grady, W.E.

    1981-01-01

    The application of XPS and UPS to the study of the initial stages of high temperature (> 350 0 C) electrochemical oxidation of iron and nickel is discussed. In the high temperature experiments, iron and nickel electrodes were electrochemically oxidized in contact with a solid oxide electrolyte in the uhv system. The great advantages of this technique are that the oxygen activity at the interface may be precisely controlled and the ability to run the reactions in uhv allows the simultaneous observation of the reactions by XPS

  11. Staged membrane oxidation reactor system

    Science.gov (United States)

    Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

    2012-09-11

    Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

  12. Single sheet iron oxides

    DEFF Research Database (Denmark)

    Yin, Zhou

    profile with reversible reduction and oxidation, suggesting the formation of FeII-OH/O-FeIII clusters as that in GRs were formed on the ITO electrode (trichloroethylene (TCE), tetrachloride (CT) and 4-chlorophenol are used to test...

  13. 21 CFR 73.3125 - Iron oxides.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.3125 Section 73.3125 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No. 1332-37-2), Color Index No. 77491, shall conform in...

  14. Functionality of the iron oxides

    International Nuclear Information System (INIS)

    Castano, J.G.; Arroyave, C.

    1998-01-01

    Some iron oxides have a great scientific and technological possibilities, not only for their importance in the present, but also for their great potential in the development of the future technologies. They have adequate properties to carry out several functions. They are plentiful in the nature and their synthetic obtention is not complex. This paper shows five of them (hematite, magnetite, maghemite, goethite and akaganeite) and their utilization in fields like chemical industry, biotechnology medicine, new materials and electromagnetism. (Author) 77 refs

  15. Accelerated dissolution of iron oxides in ice

    Directory of Open Access Journals (Sweden)

    D. Jeong

    2012-11-01

    Full Text Available Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4, the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the surface area of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

  16. Iron, Oxidative Stress and Gestational Diabetes

    Directory of Open Access Journals (Sweden)

    Taifeng Zhuang

    2014-09-01

    Full Text Available Both iron deficiency and hyperglycemia are highly prevalent globally for pregnant women. Iron supplementation is recommended during pregnancy to control iron deficiency. The purposes of the review are to assess the oxidative effects of iron supplementation and the potential relationship between iron nutrition and gestational diabetes. High doses of iron (~relative to 60 mg or more daily for adult humans can induce lipid peroxidation in vitro and in animal studies. Pharmaceutical doses of iron supplements (e.g., 10× RDA or more for oral supplements or direct iron supplementation via injection or addition to the cell culture medium for a short or long duration will induce DNA damage. Higher heme-iron intake or iron status measured by various biomarkers, especially serum ferritin, might contribute to greater risk of gestational diabetes, which may be mediated by iron oxidative stress though lipid oxidation and/or DNA damage. However, information is lacking about the effect of low dose iron supplementation (≤60 mg daily on lipid peroxidation, DNA damage and gestational diabetes. Randomized trials of low-dose iron supplementation (≤60 mg daily for pregnant women are warranted to test the relationship between iron oxidative stress and insulin resistance/gestational diabetes, especially for iron-replete women.

  17. Iron biomineralization by anaerobic neutrophilic iron-oxidizing bacteria

    DEFF Research Database (Denmark)

    Miot, Jennyfer; Benzerara, Karim; Morin, Guillaume

    2009-01-01

    Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate-dependent ......Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate...... precipitation in the periplasm (in a few tens of minutes), followed by the formation of surface-bound globules. Moreover, we frequently observed an asymmetric mineral thickening at the cell poles. In parallel, the evolution of iron oxidation was quantified by STXM: iron both contained in the bacteria...... and in the extracellular precipitates reached complete oxidation within 6 days. While a progressive oxidation of Fe in the bacteria and in the medium could be observed, spatial redox (oxido-reduction state) heterogeneities were detected at the cell poles and in the extracellular precipitates after 1 day. All...

  18. Diffusion of hydrogen in iron oxides

    International Nuclear Information System (INIS)

    Bruzzoni, P.

    1993-01-01

    The diffusion of hydrogen in transitions metals oxides has been recently studied at room temperature through the permeability electrochemical technique. This work studies thin oxide layers grown in air or in presence of oxidizing atmospheres at temperatures up to 200 deg C. The substrate was pure iron with different superficial treatments. It was observed that these oxides reduce up to three magnitudes orders, the hydrogen stationary flux through membranes of usual thickness in comparison with iron membranes free of oxide. (Author)

  19. Operation of staged membrane oxidation reactor systems

    Science.gov (United States)

    Repasky, John Michael

    2012-10-16

    A method of operating a multi-stage ion transport membrane oxidation system. The method comprises providing a multi-stage ion transport membrane oxidation system with at least a first membrane oxidation stage and a second membrane oxidation stage, operating the ion transport membrane oxidation system at operating conditions including a characteristic temperature of the first membrane oxidation stage and a characteristic temperature of the second membrane oxidation stage; and controlling the production capacity and/or the product quality by changing the characteristic temperature of the first membrane oxidation stage and/or changing the characteristic temperature of the second membrane oxidation stage.

  20. Ferrite grade iron oxides from ore rejects

    Indian Academy of Sciences (India)

    Iron oxyhydroxides and hydroxides were synthesized from chemically beneficiated high SiO2/Al2O3 low-grade iron ore (57.49% Fe2O3) rejects and heated to get iron oxides of 96–99.73% purity. The infrared band positions, isothermal weight loss and thermogravimetric and chemical analysis established the chemical ...

  1. Mechanistic Study of Monodisperse Iron Oxide Nanocrystals ...

    African Journals Online (AJOL)

    To gain better insight into the formation of iron oxide nanocrystals from the solution phase thermal decomposition of iron (III) oleate complex, different reaction conditions including time, heating ramp, as well as concentrations of iron oleate precursor and oleic acid ligand were systematically varied and the resulting ...

  2. Core-shell iron-iron oxide nanoparticles

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.

    2004-01-01

    We present studies of the magnetic properties of core-shell iron-iron oxide nanoparticles. By combining Mossbauer and X-ray absorption spectroscopy we have been able to measure the change from a Fe3O4-like to a gamma-Fe2O3-like composition from the interface to the surface. Furthermore, we have...

  3. Facile and sustainable synthesis of shaped iron oxide nanoparticles: effect of iron precursor salts on the shapes of iron oxides.

    Science.gov (United States)

    Sayed, Farheen N; Polshettiwar, Vivek

    2015-05-05

    A facile and sustainable protocol for synthesis of six different shaped iron oxides is developed. Notably, all the six shapes of iron oxides can be synthesised using exactly same synthetic protocol, by simply changing the precursor iron salts. Several of the synthesised shapes are not reported before. This novel protocol is relatively easy to implement and could contribute to overcome the challenge of obtaining various shaped iron oxides in economical and sustainable manner.

  4. Carbon-Supported Iron Oxide Particles

    DEFF Research Database (Denmark)

    Meaz, T.; Mørup, Steen; Koch, C. Bender

    1996-01-01

    A carbon black ws impregnated with 6 wt% iron using an aqueous solution of iron nitrate. The impregnated carbon was initially dried at 125 C. The effect of heating of the iron oxide phase was investigated at temperatures between 200 and 600 C using Mossbauer spectroscopy. All heat treatments were...... done in an oxygen-containing atmosphere. Ferrihydrite is formed and is stable at and below a temperature of 300 C. At 600 C small particles of maghemite is the dominant iron oxide. A transformation reaction is suggested....

  5. A single-stage functionalization and exfoliation method for the production of graphene in water: stepwise construction of 2D-nanostructured composites with iron oxide nanoparticles.

    Science.gov (United States)

    Ihiawakrim, Dris; Ersen, Ovidiu; Melin, Frédéric; Hellwig, Petra; Janowska, Izabela; Begin, Dominique; Baaziz, Walid; Begin-Colin, Sylvie; Pham-Huu, Cuong; Baati, Rachid

    2013-10-07

    A practically simple top-down process for the exfoliation of graphene (GN) and few-layer graphene (FLG) from graphite is described. We have discovered that a biocompatible amphiphilic pyrene-based hexahistidine peptide is able to exfoliate, functionalize, and dissolve few layer graphene flakes in pure water under exceptionally mild, sustainable and virtually innocuous low intensity cavitation conditions. Large area functionalized graphene flakes with the hexahistidine oligopeptide (His₆-TagGN = His₆@GN) have been produced efficiently at room temperature and characterized by TEM, Raman, and UV spectroscopy. Conductivity experiments carried out on His₆-TagGN samples revealed superior electric performances as compared to reduced graphene oxide (rGO) and non-functionalized graphene, demonstrating the non-invasive features of our non-covalent functionalization process. We postulated a rational exfoliation mechanism based on the intercalation of the peptide amphiphile under cavitational chemistry. We also demonstrated the ability of His6-TagGN nanoassemblies to self-assemble spontaneously with inorganic iron oxide nanoparticles generating magnetic two-dimensional (2D) His₆-TagGN/Fe₃O₄ nanocomposites under mild and non-hydrothermal conditions. The set of original experiments described here open novel perspectives in the facile production of water dispersible high quality GN and FLG sheets that will improve and facilitate the interfacing, processing and manipulation of graphene for promising applications in catalysis, nanocomposite construction, integrated nanoelectronic devices and bionanotechnology.

  6. When Density Functional Approximations Meet Iron Oxides.

    Science.gov (United States)

    Meng, Yu; Liu, Xing-Wu; Huo, Chun-Fang; Guo, Wen-Ping; Cao, Dong-Bo; Peng, Qing; Dearden, Albert; Gonze, Xavier; Yang, Yong; Wang, Jianguo; Jiao, Haijun; Li, Yongwang; Wen, Xiao-Dong

    2016-10-11

    Three density functional approximations (DFAs), PBE, PBE+U, and Heyd-Scuseria-Ernzerhof screened hybrid functional (HSE), were employed to investigate the geometric, electronic, magnetic, and thermodynamic properties of four iron oxides, namely, α-FeOOH, α-Fe 2 O 3 , Fe 3 O 4 , and FeO. Comparing our calculated results with available experimental data, we found that HSE (a = 0.15) (containing 15% "screened" Hartree-Fock exchange) can provide reliable values of lattice constants, Fe magnetic moments, band gaps, and formation energies of all four iron oxides, while standard HSE (a = 0.25) seriously overestimates the band gaps and formation energies. For PBE+U, a suitable U value can give quite good results for the electronic properties of each iron oxide, but it is challenging to accurately get other properties of the four iron oxides using the same U value. Subsequently, we calculated the Gibbs free energies of transformation reactions among iron oxides using the HSE (a = 0.15) functional and plotted the equilibrium phase diagrams of the iron oxide system under various conditions, which provide reliable theoretical insight into the phase transformations of iron oxides.

  7. Iron oxides characterization by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Basurto Sanchez, R.

    1993-01-01

    In this work rust development on low carbon wire surface after the conformation process at different temperatures was studied by Moessbauer spectroscopy. The characterization was made by determining the following spectral parameters; 1) Quadrupole splitting, 2) Isomer shift, and 3) Magnetic splitting. The area quantification determined the percentage amount of three different iron oxides. These iron oxides were: a) Wustite (Fe O), b) Hematite (Fe 2 O 3 ), and c) Magnetite (Fe 3 O 4 ) which were present in the rust studied. With the results it was possible to establish the best temperature to favor the development of each of these iron oxides. (Author)

  8. Ferroxidase-Mediated Iron Oxide Biomineralization

    DEFF Research Database (Denmark)

    Zeth, Kornelius; Hoiczyk, Egbert; Okuda, Mitsuhiro

    2016-01-01

    Iron oxide biomineralization occurs in all living organisms and typically involves protein compartments ranging from 5 to 100nm in size. The smallest iron-oxo particles are formed inside dodecameric Dps protein cages, while the structurally related ferritin compartments consist of twice as many......, translocation, oxidation, nucleation, and storage, that are mediated by ferroxidase centers. Thus, compartmentalized iron oxide biomineralization yields uniform nanoparticles strictly determined by the sizes of the compartments, allowing customization for highly diverse nanotechnological applications....... identical protein subunits. The largest known compartments are encapsulins, icosahedra made of up to 180 protein subunits that harbor additional ferritin-like proteins in their interior. The formation of iron-oxo particles in all these compartments requires a series of steps including recruitment of iron...

  9. Iron oxide nanoparticles stabilized inside highly ordered ...

    Indian Academy of Sciences (India)

    CdS nanoparticles prepared in reverse micellar system was incorporated into ... The molar ratio of various constituents of the hydrothermal gel was ... other synthesis techniques for the preparation of iron oxide nanocomposites using.

  10. Thermochemically active iron titanium oxide materials

    Energy Technology Data Exchange (ETDEWEB)

    Coker, Eric Nicholas; Miller, James E.

    2018-01-16

    A thermal oxidation-reduction cycle is disclosed that uses iron titanium oxide as the reactive material. The cycle may be used for the thermal splitting of water and/or carbon dioxide to form hydrogen and/or carbon monoxide. The formed compounds may be used as syngas precursors to form fuels.

  11. Exploring Microbial Iron Oxidation in Wetland Soils

    Science.gov (United States)

    Wang, J.; Muyzer, G.; Bodelier, P. L. E.; den Oudsten, F.; Laanbroek, H. J.

    2009-04-01

    Iron is one of the most abundant elements on earth and is essential for life. Because of its importance, iron cycling and its interaction with other chemical and microbial processes has been the focus of many studies. Iron-oxidizing bacteria (FeOB) have been detected in a wide variety of environments. Among those is the rhizosphere of wetland plants roots which release oxygen into the soil creating suboxic conditions required by these organisms. It has been reported that in these rhizosphere microbial iron oxidation proceeds up to four orders of magnitude faster than strictly abiotic oxidation. On the roots of these wetland plants iron plaques are formed by microbial iron oxidation which are involved in the sequestering of heavy metals as well organic pollutants, which of great environmental significance.Despite their important role being catalysts of iron-cycling in wetland environments, little is known about the diversity and distribution of iron-oxidizing bacteria in various environments. This study aimed at developing a PCR-DGGE assay enabling the detection of iron oxidizers in wetland habitats. Gradient tubes were used to enrich iron-oxidizing bacteria. From these enrichments, a clone library was established based on the almost complete 16s rRNA gene using the universal bacterial primers 27f and 1492r. This clone library consisted of mainly α- and β-Proteobacteria, among which two major clusters were closely related to Gallionella spp. Specific probes and primers were developed on the basis of this 16S rRNA gene clone library. The newly designed Gallionella-specific 16S rRNA gene primer set 122f/998r was applied to community DNA obtained from three contrasting wetland environments, and the PCR products were used in denaturing gradient gel electrophoresis (DGGE) analysis. A second 16S rRNA gene clone library was constructed using the PCR products from one of our sampling sites amplified with the newly developed primer set 122f/998r. The cloned 16S rRNA gene

  12. Iron oxides in human brain

    International Nuclear Information System (INIS)

    Cesnek, M.; Miglierini, M.; Lancok, A.

    2015-01-01

    It was confirmed that Moessbauer spectroscopy is an useful tool for measurement of biological tissues even if the concentration of iron in the samples is very low. Moessbauer spectra revealed a presence of particles with non-magnetic behaviour at room temperature. At temperature 4.2 K almost all particles exhibit magnetic behaviour. The rest of the particles still exhibits superparamagnetic behaviour what indicates that their blocking temperature is lower than 4.2 K. It was suggested that those might be very small haemosiderin particles. Parameters the sextet-like components suggest possible presence of goethite, akaganeit or ferrihydrite. Using synchrotron assisted XRD, it was not possible to reveal any iron relevant structural information due to very low concentration of iron atoms in samples. Atomic pairs with the highest contribution to PDF were revealed. All these atomic pairs are characteristic for biological materials. XRD measurement of extracted ferritin could reveal some helpful information about the iron structure. (authors)

  13. On the crystalline structures of iron oxides formed during the removal process of iron in water

    International Nuclear Information System (INIS)

    Cho, Bongyeon; Fujita, Kenji; Oda, Katsuro; Ino, Hiromitsu

    1993-01-01

    The iron oxide samples collected from both filtration and batch reactors were analysed by X-ray diffraction and Moessbauer spectroscopy. In the filtration of water containing iron, the oxidized form of iron was determined to be ferrihydrite. In contrast, in the batch experiment without filtration, iron was oxidized to microcrystalline goethite. (orig.)

  14. Characterization and uranium bioleaching performance of mixed iron- and sulfur-oxidizers versus iron-oxidizers

    International Nuclear Information System (INIS)

    Qian Li; Jing Sun; Dexin Ding; Qingliang Wang; Wenge Shi; Eming Hu; Xiaoyu Jiang; University of South China, Hengyang; Xingxing Wang

    2017-01-01

    In order to develop and apply mixed iron- and sulfur-oxidizers in uranium bioleaching, the characteristics of a mixed iron- and sulfur-oxidizing consortium (Consortium ISO) were comparatively investigated versus an iron-oxidizing consortium (Consortium IO). The results showed, the Consortium ISO exerted stronger oxidative ability and acid-producing ability than Consortium IO did. The synergy of sulfur-oxidizers and iron-oxidizers could change the structure and properties of the passivation substance, and work positively for eliminating the accumulation of passivation substance. In the bioleaching process, the uranium bioleaching experiments showed the recovery percentage of uranium reached 99.5% with Consortium ISO, 6.3% more than that of Consortium IO. (author)

  15. Metal ion binding to iron oxides

    Science.gov (United States)

    Ponthieu, M.; Juillot, F.; Hiemstra, T.; van Riemsdijk, W. H.; Benedetti, M. F.

    2006-06-01

    The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to show that it is possible to model the adsorption of protons and TE on a crystallized oxide (i.e., goethite) and on an amorphous oxide (HFO) in an identical way. Here, we use the CD-MUSIC approach in combination with valuable and reliable surface spectroscopy information about the nature of surface complexes of the TE. The other objective of this work is to obtain generic parameters to describe the binding of the following elements (Cd, Co, Cu, Ni, Pb, and Zn) onto both iron oxides for the CD-MUSIC approach. The results show that a consistent description of proton and metal ion binding is possible for goethite and HFO with the same set of model parameters. In general a good prediction of almost all the collected experimental data sets corresponding to metal ion binding to HFO is obtained. Moreover, dominant surface species are in agreement with the recently published surface complexes derived from X-ray absorption spectroscopy (XAS) data. Until more detailed information on the structure of the two iron oxides is available, the present option seems a reasonable approximation and can be used to describe complex geochemical systems. To improve our understanding and modeling of multi-component systems we need more data obtained at much lower metal ion to iron oxide ratios in order to be able to account eventually for sites that are not always characterized in spectroscopic studies.

  16. Iron oxides in human spleen.

    Science.gov (United States)

    Kopáni, Martin; Miglierini, Marcel; Lančok, Adriana; Dekan, Július; Čaplovicová, Mária; Jakubovský, Ján; Boča, Roman; Mrazova, Hedviga

    2015-10-01

    Iron is an essential element for fundamental cell functions and a catalyst for chemical reactions. Three samples extracted from the human spleen were investigated by scanning (SEM) and transmission electron microscopy (TEM), Mössbauer spectrometry (MS), and SQUID magnetometry. The sample with diagnosis of hemosiderosis (H) differs from that referring to hereditary spherocytosis and the reference sample. SEM reveals iron-rich micrometer-sized aggregate of various structures-tiny fibrils in hereditary spherocytosis sample and no fibrils in hemochromatosis. Hematite and magnetite particles from 2 to 6 μm in TEM with diffraction in all samples were shown. The SQUID magnetometry shows different amount of diamagnetic, paramagnetic and ferrimagnetic structures in the tissues. The MS results indicate contribution of ferromagnetically split sextets for all investigated samples. Their occurrence indicates that at least part of the sample is magnetically ordered below the critical temperature. The iron accumulation process is different in hereditary spherocytosis and hemosiderosis. This fact may be the reason of different iron crystallization.

  17. Molecular and parametric imaging with iron oxides

    International Nuclear Information System (INIS)

    Matuszewski, L.; Bremer, C.; Tombach, B.; Heindel, W.

    2007-01-01

    Superparamagnetic iron oxide (SPIO) contrast agents, clinically established for high resolution magnetic resonance imaging of reticuloendothelial system containing anatomical structures, can additionally be exploited for the non-invasive characterization and quantification of pathology down to the molecular level. In this context, SPIOs can be applied for non-invasive cell tracking, quantification of tissue perfusion and target specific imaging, as well as for the detection of gene expression. This article provides an overview of new applications for clinically approved iron oxides as well of new, modified SPIO contrast agents for parametric and molecular imaging. (orig.) [de

  18. Water clustering on nanostructured iron oxide films

    DEFF Research Database (Denmark)

    Merte, Lindsay Richard; Bechstein, Ralf; Peng, G.

    2014-01-01

    , but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer...... islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous...

  19. Surface oxidation phenomena of boride coatings grown on iron

    International Nuclear Information System (INIS)

    Carbucicchio, M.; Palombarini, G.; Sambogna, G.

    1992-01-01

    Very hard boride coatings are grown on various metals using thermochemical as well as chemical vapour deposition techniques. In this way many surface properties, and in particular the wear resistance, can be considerably improved. Usually, also the corrosion behaviour of the treated components is important. In particular, oxidizing atmospheres are involved in many applications where, therefore, coating-environment interactions can play a relevant role. In a previous work, the early stages of the oxidation of iron borides were studied by treating single phase compacted powders in flowing oxygen at low temperatures (300-450deg C). In the present paper, the attention is addressed to the oxidation of both single phase and polyphase boride coatings thermochemically grown on iron. The single phase boride coatings were constituted by Fe 2 B, while the polyphase coatings were constituted by an inner Fe 2 B layer and an outer FeB-base layer. All the boride layers displayed strong (002) preferred crystallographic orientations. (orig.)

  20. Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

    Science.gov (United States)

    Evans, K.; Ferris, F.

    2009-05-01

    At concentrations above 1 mg/L, fluoride in drinking water can lead to dental and skeletal fluorosis, a disease that causes mottling of the teeth, calcification of ligaments, crippling bone deformities and many other physiological disorders that can, ultimately, lead to death. Conservative estimates are that fluorosis afflicts tens of millions of people worldwide. As there is no treatment for fluorosis, prevention is the only means of controlling the disease. While numerous defluoridation techniques have been explored, no single method has been found to be both effective and inexpensive enough to implement widely. Our research began in India, with a large-scale geochemical study of the groundwater in a fluoride-contaminated region of Orissa. Having developed a better understanding of the geochemical relationships that exist between fluoride and other parameters present in an affected area, as well as the complex relationships that arise among those parameters that can impact the presence of fluoride, we began investigating certain remediation scenarios involving iron oxides. A common approach to remediation involves the partitioning of fluoride from groundwater by sorption onto a variety of materials, one of the most effective of which is iron oxide whose surface area acts as a scavenger for fluoride. In the presence of iron oxidizing bacteria, the oxidation rate of iron has been shown to be ˜6 times greater than in their absence; fluoride should, therefore, be removed from an aqueous environment by bacteriogenic iron oxides (BIOS) much more quickly than by abiotic iron oxides. Most recently, sorption studies have been conducted using both BIOS and synthetic hydrous ferric oxides in order to compare the behavior between biotic and abiotic sorbents. These studies have provided sorption isotherms that allow comparison of fluoride removed by sorption to BIOS versus synthetic iron oxides. Sorption affinity constants have also been determined, which allow for the

  1. Synthesis of iron oxide nanoparticles of narrow size distribution on ...

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. We report here the preparation of nanoparticles of iron oxide in the presence of polysaccharide templates. ... using different chemical methods viz. sonochemical, sol- .... 3.2 Characterization of iron oxide prepared by template assisted ...

  2. Iron oxide nanoparticles stabilized inside highly ordered ...

    Indian Academy of Sciences (India)

    Nanosized iron oxide, a moderately large band-gap semiconductor and an essential component of optoelectrical and magnetic devices, has been prepared successfully inside the restricted internal pores of mesoporous silica material through in-situ reduction during impregnation. The samples were characterized by ...

  3. Dextran-modified iron oxide nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Hradil, Jiří; Pisarev, A. G.; Babič, Michal; Horák, Daniel

    2007-01-01

    Roč. 5, 1-2 (2007), s. 162-168 ISSN 1672-2515 R&D Projects: GA ČR GA203/05/2256 Institutional research plan: CEZ:AV0Z40500505 Keywords : iron oxide * nanoparticles * dextran Subject RIV: CD - Macromolecular Chemistry

  4. 21 CFR 73.1200 - Synthetic iron oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically prepared...

  5. 21 CFR 73.200 - Synthetic iron oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically prepared...

  6. Acid monolayer functionalized iron oxide nanoparticle catalysts

    Science.gov (United States)

    Ikenberry, Myles

    Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80° and starch at 130°, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide

  7. Synthesis engineering of iron oxide raspberry-shaped nanostructures.

    Science.gov (United States)

    Gerber, O; Pichon, B P; Ihiawakrim, D; Florea, I; Moldovan, S; Ersen, O; Begin, D; Grenèche, J-M; Lemonnier, S; Barraud, E; Begin-Colin, S

    2017-01-07

    Magnetic porous nanostructures consisting of oriented aggregates of iron oxide nanocrystals display very interesting properties such as a lower oxidation state of magnetite, and enhanced saturation magnetization in comparison with individual nanoparticles of similar sizes and porosity. However, the formation mechanism of these promising nanostructures is not well understood, which hampers the fine tuning of their magnetic properties, for instance by doping them with other elements. Therefore the formation mechanism of porous raspberry shaped nanostructures (RSNs) synthesized by a one-pot polyol solvothermal method has been investigated in detail from the early stages by using a wide panel of characterization techniques, and especially by performing original in situ HR-TEM studies in temperature. A time-resolved study showed the intermediate formation of an amorphous iron alkoxide phase with a plate-like lamellar structure (PLS). Then, the fine investigation of PLS transformation upon heating up to 500 °C confirmed that the synthesis of RSNs involves two iron precursors: the starting one (hydrated iron chlorides) and the in situ formed iron alkoxide precursor which decomposes with time and heating and contributes to the growth step of nanostructures. Such an understanding of the formation mechanism of RSNs is necessary to envision efficient and rational enhancement of their magnetic properties.

  8. Formation of iron oxides from acid mine drainage and magnetic separation of the heavy metals adsorbed iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hee Won; Kim, Jeong Jin; Kim, Young Hun [Andong National University, Andong (Korea, Republic of); Ha, Dong Woo [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)

    2016-03-15

    There are a few thousand abandoned metal mines in South Korea. The abandoned mines cause several environmental problems including releasing acid mine drainage (AMD), which contain a very high acidity and heavy metal ions such as Fe, Cu, Cd, Pb, and As. Iron oxides can be formed from the AMD by increasing the solution pH and inducing precipitation. Current study focused on the formation of iron oxide in an AMD and used the oxide for adsorption of heavy metals. The heavy metal adsorbed iron oxide was separated with a superconducting magnet. The duration of iron oxide formation affected on the type of mineral and the degree of magnetization. The removal rate of heavy metal by the adsorption process with the formed iron oxide was highly dependent on the type of iron oxide and the solution pH. A high gradient magnetic separation (HGMS) system successfully separated the iron oxide and harmful heavy metals.

  9. Factors Affecting Ballability of Mixture Iron Ore Concentrates and Iron Oxide Bearing Wastes in Metallurgical Processing

    Directory of Open Access Journals (Sweden)

    Mfon Udo

    2018-05-01

    Full Text Available Iron oxide bearing wastes (IROBEWAS are produced at every segment of processing stage of sinter, molten iron and steel production. They are hard to handle and in many cases are stockpiled only to be a source of environmental pollution but can be balled into pellets. Pellet of good ballability values are transportable and recyclable as they can withstand stress they will encounter without disintegrating back to dust. But ballability is affected by some factors like the grain sizes of the materials, the moisture and binder contents of the ball mix, wettability of the balled materials and the processing perimeters of the granulator. The objective of this research work is to investigate the factors affecting ballability of mixture of iron ore concentrates and iron oxide bearing wastes (IROBEWAS in metallurgical processing. The parameters under consideration were grain size of materials, the moisture contents, the speed of balling disc, IROBEWAS and Bentonite (Binder contents of the balled mix. This was carried out by balling different volume fractions of mix containing iron oxide concentrate and IROBEWAS using a balling disc and testing the resulting balls for green compressive strength using universal testing machine. It was found that the ballability of the mixture of iron ore concentrate and IROBEWAS increases as grain sizes of the materials reduce but increases as the moisture contents and IROBEWAS content increase up to an optimum value of moisture content in the mix before it starts to reduce. The ballability also increases as the speed of the granulator (Balling disc increases within the limit of this work. It was also observed that there was an increase in ballability with slight increase in bentonite content in the mix.

  10. Optical properties of iron oxides

    Science.gov (United States)

    Musfeldt, Janice

    2012-02-01

    Magnetoelectric coupling in materials like multiferroics, dilute magnetic semiconductors, and topological insulators has attracted a great deal of attention, although most work has been done in the static limit. Optical spectroscopy offers a way to investigate the dynamics of charge-spin coupling, an area where there has been much less effort. Using these techniques, we discovered that charge fluctuation in LuFe2O4, the prototypical charge ordered multiferroic, has an onset well below the charge ordering transition, supporting the ``order by fluctuation'' mechanism for the development of charge order superstructure. Bragg splitting and large magneto-optical contrast suggest a low temperature monoclinic distortion that can be driven by both temperature and magnetic field. At the same time, dramatic splitting of the LuO2 layer phonon mode is attributed to charge-rich/poor proximity effects, and its temperature dependence reveals the antipolar nature of the W layer pattern. Using optical techniques, we also discovered that α-Fe2O3, a chemically-similar parent compound and one of the world's oldest and most iconic antiferromagnetic materials, appears more red in applied magnetic field than in zero field conditions. This effect is driven by a field-induced reorientation of magnetic order. The oscillator strength lost in the color band is partially transferred to the magnon side band, a process that also reveals a new exciton pattern induced by the modified exchange coupling. Analysis of the exciton pattern exposes C2/c monoclinic symmetry in the high field phase of hematite. Taken together, these findings advance our understanding of iron-based materials under extreme conditions. [4pt] Collaborators include: X. S. Xu, P. Chen, Q. -C. Sun, T. V. Brinzari (Tennessee); S. McGill (NHMFL); J. De Groot, M. Angst, R. P. Hermann (Julich); A. D. Christianson, B. C. Sales, D. Mandrus (ORNL); A. P. Litvinchuk (Houston); J. -W. Kim (Ames); Z. Islam (Argonne); N. Lee, S. -W. Cheong

  11. Thermally stimulated iron oxide transformations and magnetic behaviour of cerium dioxide/iron oxide reactive sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Luňáček, J., E-mail: jiri.lunacek@vsb.cz [Department of Physics, VŠB – Technical University of Ostrava, 17, listopadu 15/2172, 708 33 Ostrava-Poruba (Czech Republic); Department 606, VŠB – Technical University of Ostrava, 17, listopadu 15/2172, 708 33 Ostrava-Poruba (Czech Republic); Životský, O. [Department of Physics, VŠB – Technical University of Ostrava, 17, listopadu 15/2172, 708 33 Ostrava-Poruba (Czech Republic); Department 606, VŠB – Technical University of Ostrava, 17, listopadu 15/2172, 708 33 Ostrava-Poruba (Czech Republic); Jirásková, Y. [CEITEC IPM, Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); Buršík, J. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); Janoš, P. [Faculty of the Environment, University of Jan Evangelista Purkyně, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

    2016-10-15

    The present paper is devoted to detailed study of the magnetically separable sorbents based on a cerium dioxide/iron oxide composite annealed at temperatures T{sub a} = 773 K, 873 K, and 973 K. The X-ray diffraction and high resolution transmission electron microscopy are used to determine the phase composition and microstructure morphology. Mössbauer spectroscopy at room (300 K) and low (5 K) temperatures has contributed to more exact identification of iron oxides and their transformations Fe{sub 3}O{sub 4} → γ-Fe{sub 2}O{sub 3} (ε-Fe{sub 2}O{sub 3}) → α-Fe{sub 2}O{sub 3} in dependence on calcination temperature. Different iron oxide phase compositions and grain size distributions influence the magnetic characteristics determined from the room- and low-temperature hysteresis loop measurements. The results are supported by zero-field-cooled and field-cooled magnetization measurements allowing a quantitative estimation of the grain size distribution and its effect on the iron oxide transformations. - Highlights: •Magnetically separable sorbents based on a CeO{sub 2}/Fe{sub 2}O{sub 3} composite were investigated. •Microstructure of sorbents was determined by XRD, TEM and Mössbauer spectroscopy. •Magnetic properties were studied by hysteresis loops at room- and low-temperatures. •Phase transitions of iron oxides with increasing annealing temperature are observed.

  12. Deactivation of iron oxide used in the steam-iron process to produce hydrogen

    NARCIS (Netherlands)

    Bleeker, M.F.; Veringa, H.J.; Kersten, Sascha R.A.

    2009-01-01

    In the steam-iron process pure hydrogen can be produced from any hydrocarbon feedstock by using a redox cycle of iron oxide. One of the main problems connected to the use of the iron oxide is the inherent structural changes that take place during oxygen loading and unloading leading to severe

  13. Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

    Science.gov (United States)

    Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

    1993-01-01

    An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

  14. Structure and growth of oxide on iron-chromium alloys

    International Nuclear Information System (INIS)

    Cox, M.G.C.; McEnaney, B.; Scott, V.D.

    1974-01-01

    Several oxides form during the initial stages of oxidation of iron-chromium alloys at 400 to 600 0 C in CO 2 -1%CO gas. The nature of the oxidation product depends upon crystallographic orientation and composition of the substrate, and can be explained by considering the maximum solubility of chromium in different oxide phases together with interfacial and strain energy factors. Kinetics of oxidation together with micrographic observations indicate that, as oxidation proceeds spinel oxide M 3 O 4 nucleates at sites on the substrate surface associated with asperities. The spinel nuclei grow laterally and vertically until they coalesce and the scale subsequently thickens according to a parabolic rate law. The duplex structure of scales is interpreted in terms of an outward diffusion of cations together with simultaneous growth of an inner layer in the space created by this outward movement. Scale porosity provides a route for gas-phase transport of oxidant to support the growth of the inner layer. Regularly spaced lamellar voids which may form in the inner layer are believed to be associated with a cyclic vacancy condensation process. Enrichment of the inner layer in chromium is explained by analysis of the possible diffusion path networks in close-packed oxides. Some comments are made concerning possible practical applications of these data. (author)

  15. Iron Oxide Deposition from Aqueous Solution and Iron Formations on Mars

    Science.gov (United States)

    Catling, David; Moore, Jeff

    2000-01-01

    Iron formations are ancient, laminated chemical sediments containing at least 15 wt% Fe. We discuss possible mechanisms for their formation in aqueous environments on early Mars. Such iron oxide deposits may be detectable today.

  16. Isolation of microorganisms involved in reduction of crystalline iron(III) oxides in natural environments.

    Science.gov (United States)

    Hori, Tomoyuki; Aoyagi, Tomo; Itoh, Hideomi; Narihiro, Takashi; Oikawa, Azusa; Suzuki, Kiyofumi; Ogata, Atsushi; Friedrich, Michael W; Conrad, Ralf; Kamagata, Yoichi

    2015-01-01

    Reduction of crystalline Fe(III) oxides is one of the most important electron sinks for organic compound oxidation in natural environments. Yet the limited number of isolates makes it difficult to understand the physiology and ecological impact of the microorganisms involved. Here, two-stage cultivation was implemented to selectively enrich and isolate crystalline iron(III) oxide reducing microorganisms in soils and sediments. Firstly, iron reducers were enriched and other untargeted eutrophs were depleted by 2-years successive culture on a crystalline ferric iron oxide (i.e., goethite, lepidocrocite, hematite, or magnetite) as electron acceptor. Fifty-eight out of 136 incubation conditions allowed the continued existence of microorganisms as confirmed by PCR amplification. High-throughput Illumina sequencing and clone library analysis based on 16S rRNA genes revealed that the enrichment cultures on each of the ferric iron oxides contained bacteria belonging to the Deltaproteobacteria (mainly Geobacteraceae), followed by Firmicutes and Chloroflexi, which also comprised most of the operational taxonomic units (OTUs) identified. Venn diagrams indicated that the core OTUs enriched with all of the iron oxides were dominant in the Geobacteraceae while each type of iron oxides supplemented selectively enriched specific OTUs in the other phylogenetic groups. Secondly, 38 enrichment cultures including novel microorganisms were transferred to soluble-iron(III) containing media in order to stimulate the proliferation of the enriched iron reducers. Through extinction dilution-culture and single colony isolation, six strains within the Deltaproteobacteria were finally obtained; five strains belonged to the genus Geobacter and one strain to Pelobacter. The 16S rRNA genes of these isolates were 94.8-98.1% identical in sequence to cultured relatives. All the isolates were able to grow on acetate and ferric iron but their physiological characteristics differed considerably in

  17. Nitric oxide and plant iron homeostasis.

    Science.gov (United States)

    Buet, Agustina; Simontacchi, Marcela

    2015-03-01

    Like all living organisms, plants demand iron (Fe) for important biochemical and metabolic processes. Internal imbalances, as a consequence of insufficient or excess Fe in the environment, lead to growth restriction and affect crop yield. Knowledge of signals and factors affecting each step in Fe uptake from the soil and distribution (long-distance transport, remobilization from old to young leaves, and storage in seeds) is necessary to improve our understanding of plant mineral nutrition. In this context, the role of nitric oxide (NO) is discussed as a key player in maintaining Fe homeostasis through its cross talk with hormones, ferritin, and frataxin and the ability to form nitrosyl-iron complexes. © 2015 New York Academy of Sciences.

  18. Roentgenoelectronic investigation into oxidation of iron-chromium and iron-chromium-nickel alloys

    International Nuclear Information System (INIS)

    Akimov, A.G.; Rozenfel'd, I.L.; Kazanskij, L.P.; Machavariani, G.V.

    1978-01-01

    Kinetics of iron-chromium and iron-chromium-nickel alloy oxidation (of the Kh13 and Kh18N10T steels) in oxygen was investigated using X-ray electron spectroscopy. It was found that according to X-ray electron spectra chromium oxidation kinetics in the iron-chromium alloy differs significantly from oxidation kinetics of chromium pattern. Layer by layer X-ray electron analysis showed that chromium is subjected to a deeper oxidation as compared to iron, and accordingly, Cr 2 O 3 layer with pure iron impregnations is placed between the layer of mixed oxide (Fe 3 O 4 +Cr 2 O 3 ) and metal. A model of the iron-chromium alloy surface is suggested. The mixed oxide composition on the steel surface is presented as spinel Fesub(2+x)Crsub(1-x)Osub(y)

  19. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    H.Y. Sohn

    2008-03-31

    The objective of the project is to develop a new ironmaking technology based on hydrogen and fine iron oxide concentrates in a suspension reduction process. The ultimate objective of the new technology is to replace the blast furnace and to drastically reduce CO2 emissions in the steel industry. The goals of this phase of development are; the performance of detailed material and energy balances, thermochemical and equilibrium calculations for sulfur and phosphorus impurities, the determination of the complete kinetics of hydrogen reduction and bench-scale testing of the suspension reduction process using a large laboratory flash reactor.

  20. Stage IV in electrical resistivity return to alpha-iron

    International Nuclear Information System (INIS)

    Poltavtseva, V.P.

    2004-01-01

    Full text: In compliance with the model of two interstitial atoms, in returning the electrical resistivity increment, the stage IV, related to migration of mono vacancies, should exist. Unfortunately, for alpha-iron there is no any reliable proof of existence of the stage IV (450-630 K) up to now. As a rule, the annealing stages revealed within this temperature range are considered as related to impurity effects. This paper is aimed at detection of the stage IV in returning the electrical resistivity increment in alpha-iron by means of irradiation of the materials differing in purity degree (99.99 and 99.8 %) by 30 MeV protons capable to create large amount of point defects and small clusters in BCC metals. By author opinion, it will make it possible to reach the radiation defect/vacancy concentrations comparable with contents of impurities (C and N) and, thus, to obtain an information about their migration. As a result of irradiation by protons at 270 K up to the fluence comprising 2.3·10 21 m -2 (0.001 dpa), the following has been found: - an increase in the electrical resistivity at 330 K is 0.84 and 0.61 nΩ·m for the alpha-iron purity degree 99.99 and 99.8 % respectively; - in the 99.99 % purity degree alpha-iron the process of electrical resistivity restoration comes to an end completely at 563 K, whereas in alpha-iron with larger content of impurity - at nearly 600 K; - in the 99.99% purity degree alpha iron electrical resistivity return spectrum a single wide peak centered at 445 K and two smeared peaks below 400 and higher than 490 K are revealed. As the impurity content increases, the 464 K peak changes the 445 K peak, which is about twice lower. Besides, a peak at 377 K occurs, and the peak at a temperature higher than 500 K, in contrast to the 99.99 % purity degree alpha-iron, has a point of inflection at 590 K. On a base of the data obtained, one may conclude that the stage centered around 445 K is of intrinsic nature, and the 99.99 % purity degree

  1. Review of iron oxides for water treatment

    International Nuclear Information System (INIS)

    Navratil, J. D.

    2001-01-01

    Many processes have utilized iron oxides for the treatment of liquid wastes containing radioactive and hazardous metals. These processes have included adsorption, precipitation and other chemical and physical techniques. For example, a radioactive wastewater precipitation process includes addition of a ferric hydroxide floc to scavenge radioactive contaminants, such as americium, plutonium and uranium. Some adsorption processes for wastewater treatment have utilized ferrites and a variety of iron containing minerals. Various ferrites and natural magnetite were used in batch modes for actinide and heavy metal removal from wastewater. Supported magnetite was also used in a column mode, and in the presence of an external magnetic field, enhanced capacity was found for removal of plutonium and americium from wastewater. These observations were explained by a nano-level high gradient magnetic separation effect, as americium, plutonium and other hydrolytic metals are known to form colloidal particles at elevated pHs. Recent modeling work supports this assumption and shows that the smaller the magnetite particle the larger the induced magnetic field around the particle from the external field. Other recent studies have demonstrated the magnetic enhanced removal of arsenic, cobalt and iron from simulated groundwater. (author)

  2. Toxicity of iron oxide nanoparticles against osteoblasts

    International Nuclear Information System (INIS)

    Shi Sifeng; Jia Jingfu; Guo Xiaokui; Zhao Yaping; Liu Boyu; Chen Desheng; Guo Yongyuan; Zhang Xianlong

    2012-01-01

    Magnetic nanoparticles have been widely used for tissue repair, magnetic resonance imaging, immunoassays and drug delivery. They are very promising in orthopaedic applications and several magnetic nanoparticles have been exploited for the treatment of orthopaedic disease. Here, we conducted an in vitro study to examine the interaction of magnetic iron oxide nanoparticles with human osteoblasts to evaluate the dose-related toxicity of the nanoparticles on osteoblasts. A transmission electron microscope was used to visualise the internalised magnetic nanoparticles in osteoblasts. The CCK-8 results revealed increased cell viability (107.5 % vitality compared with the control group) when co-cultured at a low concentration (20 μg/mL) and decreased cell viability (59.5 % vitality in a concentration of 300 μg/mL and 25.9 % in 500 μg/mL) when co-cultured in high concentrations. The flow cytometric detection revealed similar results with 5.48 % of apoptosis in a concentration of 20 μg/mL, 23.40 % of apoptosis in a concentration of 300 μg/mL and 28.49 % in a concentration of 500 μg/mL. The disrupted cytoskeleton of osteoblasts was also revealed using a laser scanning confocal microscope. We concluded that use of a low concentration of magnetic iron oxide nanoparticles is important to avoid damage to osteoblasts.

  3. Toxicity of iron oxide nanoparticles against osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Shi Sifeng [Shanghai Jiao Tong University, Department of Orthopaedic Surgery, Shanghai Sixth People' s Hospital (China); Jia Jingfu [Shanghai Jiao Tong University, School of Chemistry and Chemical Technology (China); Guo Xiaokui [Shanghai Jiao Tong University School of Medicine, Department of Medical Microbiology and Parasitology, Institutes of Medical Sciences (China); Zhao Yaping [Shanghai Jiao Tong University, School of Chemistry and Chemical Technology (China); Liu Boyu [Shanghai Jiao Tong University School of Medicine, Department of Medical Microbiology and Parasitology, Institutes of Medical Sciences (China); Chen Desheng; Guo Yongyuan; Zhang Xianlong, E-mail: zhangxianlong20101@163.com [Shanghai Jiao Tong University, Department of Orthopaedic Surgery, Shanghai Sixth People' s Hospital (China)

    2012-09-15

    Magnetic nanoparticles have been widely used for tissue repair, magnetic resonance imaging, immunoassays and drug delivery. They are very promising in orthopaedic applications and several magnetic nanoparticles have been exploited for the treatment of orthopaedic disease. Here, we conducted an in vitro study to examine the interaction of magnetic iron oxide nanoparticles with human osteoblasts to evaluate the dose-related toxicity of the nanoparticles on osteoblasts. A transmission electron microscope was used to visualise the internalised magnetic nanoparticles in osteoblasts. The CCK-8 results revealed increased cell viability (107.5 % vitality compared with the control group) when co-cultured at a low concentration (20 {mu}g/mL) and decreased cell viability (59.5 % vitality in a concentration of 300 {mu}g/mL and 25.9 % in 500 {mu}g/mL) when co-cultured in high concentrations. The flow cytometric detection revealed similar results with 5.48 % of apoptosis in a concentration of 20 {mu}g/mL, 23.40 % of apoptosis in a concentration of 300 {mu}g/mL and 28.49 % in a concentration of 500 {mu}g/mL. The disrupted cytoskeleton of osteoblasts was also revealed using a laser scanning confocal microscope. We concluded that use of a low concentration of magnetic iron oxide nanoparticles is important to avoid damage to osteoblasts.

  4. Bismuth iron oxide thin films using atomic layer deposition of alternating bismuth oxide and iron oxide layers

    Energy Technology Data Exchange (ETDEWEB)

    Puttaswamy, Manjunath; Vehkamäki, Marko [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Kukli, Kaupo, E-mail: kaupo.kukli@helsinki.fi [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); University of Tartu, Institute of Physics, W. Ostwald 1, EE-50411 Tartu (Estonia); Dimri, Mukesh Chandra [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Kemell, Marianna; Hatanpää, Timo; Heikkilä, Mikko J. [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Mizohata, Kenichiro [University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 Helsinki (Finland); Stern, Raivo [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Ritala, Mikko; Leskelä, Markku [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland)

    2016-07-29

    Bismuth iron oxide films with varying contributions from Fe{sub 2}O{sub 3} or Bi{sub 2}O{sub 3} were prepared using atomic layer deposition. Bismuth (III) 2,3-dimethyl-2-butoxide, was used as the bismuth source, iron(III) tert-butoxide as the iron source and water vapor as the oxygen source. The films were deposited as stacks of alternate Bi{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} layers. Films grown at 140 °C to the thickness of 200–220 nm were amorphous, but crystallized upon post-deposition annealing at 500 °C in nitrogen. Annealing of films with intermittent bismuth and iron oxide layers grown to different thicknesses influenced their surface morphology, crystal structure, composition, electrical and magnetic properties. Implications of multiferroic performance were recognized in the films with the remanent charge polarization varying from 1 to 5 μC/cm{sup 2} and magnetic coercivity varying from a few up to 8000 A/m. - Highlights: • Bismuth iron oxide thin films were grown by atomic layer deposition at 140 °C. • The major phase formed in the films upon annealing at 500 °C was BiFeO{sub 3}. • BiFeO{sub 3} films and films containing excess Bi favored electrical charge polarization. • Slight excess of iron oxide enhanced saturative magnetization behavior.

  5. Synthesis and magnetic characterizations of uniform iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Jiang, FuYi; Li, XiaoYi; Zhu, Yuan; Tang, ZiKang

    2014-01-01

    Uniform iron oxide nanoparticles with a cubic shape were prepared by the decomposition of homemade iron oleate in 1-octadecene with the presence of oleic acid. The particle shape and size uniformity are sensitive to the quantity of oleic acid. XRD, HRTEM and SAED results indicated that the main phase content of as-prepared iron oxide nanoparticles is Fe 3 O 4 with an inverse spinel structure. Magnetic measurements revealed that the as-prepared iron oxide nanoparticles display a ferromagnetic behavior with a blocking temperature of 295 K. At low temperatures the magnetic anisotropy of the aligned nanoparticles caused the appearance of a hysteresis loop.

  6. Iron oxides as a cause of GPR reflections

    NARCIS (Netherlands)

    van Dam, R.L.; Schlager, W.; Dekkers, M.; Huisman, J.A.

    2002-01-01

    Iron oxides frequently occur as secondary precipitates in both modern and ancient sediments and may form bands or irregular patterns. We show from time-domain reflectometry (TDR) field studies that goethite iron-oxide precipitates significantly lower the electromagnetic wave velocity of sediments.

  7. Amorphous structure of iron oxide of bacterial origin

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Hideki; Fujii, Tatsuo [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Kohara, Shinji [Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198 (Japan); Asaoka, Hiroshi [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Kusano, Yoshihiro [Department of Fine and Applied Arts, Kurashiki University of Science and the Arts, Kurashiki, Okayama 712-8505 (Japan); Ikeda, Yasunori [Research Institute for Production Development, Sakyo-ku, Kyoto 606-0805 (Japan); Nakanishi, Makoto [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Benino, Yasuhiko; Nanba, Tokuro [Graduate School of Environmental Science, Okayama University, Okayama 700-8530 (Japan); Takada, Jun, E-mail: jtakada@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); JST, CREST, Okayama 700-8530 (Japan)

    2012-12-14

    In nature, there are various iron oxides produced by the water-habitant bacterial group called 'iron-oxidizing bacteria'. These iron oxides have been studied mainly from biological and geochemical perspectives. Today, attempts are made to use such iron oxides as novel functional materials in several applications. However, their quantitative structural characteristics are still unclear. We studied the structure of iron oxide of microtubular form consisting of amorphous nanoparticles formed by an iron-oxidizing bacterium, Leptothrix ochracea, using a combination of high-energy X-ray diffraction and reverse Monte Carlo simulation. We found that its structure consists of a framework of corner- and edge-sharing distorted FeO{sub 6} octahedral units, while SiO{sub 4} tetrahedral units are isolated in the framework. The results reveal the atomic arrangement of iron oxide of bacterial origin, which is essential for investigating its potential as a functional material. -- Highlights: Black-Right-Pointing-Pointer The amorphous structure of bacterial iron oxide was investigated. Black-Right-Pointing-Pointer The structure was simulated by high-energy X-ray diffraction and reverse Monte Carlo simulation. Black-Right-Pointing-Pointer The structure was constructed of a framework of corner- and edge-sharing distorted FeO{sub 6} octahedral units. Black-Right-Pointing-Pointer SiO{sub 4} tetrahedral units were distributed isolatedly in the framework of FeO{sub 6} octahedral units.

  8. Investigation of carrier oil stabilized iron oxide nanoparticles and its ...

    African Journals Online (AJOL)

    Iron oxide nanoparticles were synthesized by co-precipitation method. The polyunsaturated carrier oil (flaxseed oil) is used as a stabilizing agent for iron oxide nanoparticles. Kirby Bauer method was used to investigate the antibiotic sensitivity of carrier oil stabilized and uncoated SPIONs at 10 and 20 μg/L on Gram-positive ...

  9. Structural and magnetic properties of core-shell iron-iron oxide nanoparticles

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.

    2002-01-01

    We present studies of the structural and magnetic properties of core-shell iron-iron oxide nanoparticles. alpha-Fe nanoparticles were fabricated by sputtering and subsequently covered with a protective nanocrystalline oxide shell consisting of either maghaemite (gamma-Fe2O3) or partially oxidized...... magnetite (Fe3O4). We observed that the nanoparticles were stable against further oxidation, and Mossbauer spectroscopy at high applied magnetic fields and low temperatures revealed a stable form of partly oxidized magnetite. The nanocrystalline structure of the oxide shell results in strong canting...... of the spin structure in the oxide shell, which thereby modifies the magnetic properties of the core-shell nanoparticles....

  10. Synthesis and characterization of dextran-coated iron oxide nanoparticles

    Science.gov (United States)

    Predescu, Andra Mihaela; Matei, Ecaterina; Berbecaru, Andrei Constantin; Pantilimon, Cristian; Drăgan, Claudia; Vidu, Ruxandra; Predescu, Cristian; Kuncser, Victor

    2018-03-01

    Synthesis and characterization of iron oxide nanoparticles coated with a large molar weight dextran for environmental applications are reported. The first experiments involved the synthesis of iron oxide nanoparticles which were coated with dextran at different concentrations. The synthesis was performed by a co-precipitation technique, while the coating of iron oxide nanoparticles was carried out in solution. The obtained nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry, Fourier transform infrared spectroscopy and superconducting quantum interference device magnetometry. The results demonstrated a successful coating of iron oxide nanoparticles with large molar weight dextran, of which agglomeration tendency depended on the amount of dextran in the coating solution. SEM and TEM observations have shown that the iron oxide nanoparticles are of about 7 nm in size.

  11. Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers

    DEFF Research Database (Denmark)

    Huang, Li‐Zhi; Ayala‐Luis, Karina B.; Fang, Liping

    2013-01-01

    hydroxide planar layer were preserved during the oxidation, as shown by FTIR spectroscopy. The high positive charge in the hydroxide layer produced by the oxidation of iron(II) to iron(III) is partially compensated by the deprotonation of hydroxy groups, as shown by X‐ray photoelectron spectroscopy...... between the alkyl chains of the intercalated dodecanoate anions play a crucial role in stabilizing the structure and hindering the collapse of the iron(II)–iron(III) (hydr)oxide structure during oxidation. This is the first report describing the formation of a stable planar layered octahedral iron......(III) (hydr)oxide. oxGRC12 shows promise as a sorbent and host for hydrophobic reagents, and as a possible source of single planar layers of iron(III) (hydr)oxide....

  12. Preparation of yttrium iron garnet (YIG) by modified domestic iron oxide

    International Nuclear Information System (INIS)

    Mozaffari, M.; Amighian

    2002-01-01

    Iron oxide by product of a local steel complex was modified to use for preparation of Yttrium iron garnet (YIG). The improvement was necessary to reduce impurities, especially the Si0 2 and Cl contents, which have deteriorative effects on magnetic properties and equipment used for preparation of the samples. The modified iron oxide was then mixed with Yttrium oxide of Merck Company in appropriate proportion to obtain a stoichiometric single phase YIG, using the conventional ceramic technique. XRD and SEM equipments were used to identify the resulting phases and microstructure respectively. Magnetic parameters were measured by VSM. Curie temperature of the samples was obtained by DTG (M) method. The results were compared with those obtained from samples that made by Merck iron oxide. There are small differences between the results. This was discussed according to extra pores and minute secondary phase in the samples made by domestic iron oxide. (Author)

  13. Fabrication and characterization of iron oxide dextran composite layers

    Science.gov (United States)

    Iconaru, S. L.; Predoi, S. A.; Beuran, M.; Ciobanu, C. S.; Trusca, R.; Ghita, R.; Negoi, I.; Teleanu, G.; Turculet, S. C.; Matei, M.; Badea, Monica; Prodan, A. M.

    2018-02-01

    Super paramagnetic iron oxide nanoparticles such as maghemite have been shown to exhibit antimicrobial properties [1-5]. Moreover, the iron oxide nanoparticles have been proposed as a potential magnetically controllable antimicrobial agent which could be directed to a specific infection [3-5]. The present research has focused on studies of the surface and structure of iron oxide dextran (D-IO) composite layers surface and structure. These composite layers were deposited on Si substrates. The structure of iron oxide dextran composite layers was investigated by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) while the surface morphology was evaluated by Scanning Electron Microscopy (SEM). The structural characterizations of the iron oxide dextran composite layers revealed the basic constituents of both iron and dextran structure. Furthermore, the in vitro evaluation of the antifungal effect of the complex layers, which have been shown revealed to be active against C. albicans cells at distinct intervals of time, is exhibited. Our research came to confirm the fungicidal effect of iron oxide dextran composite layers. Also, our results suggest that iron oxide dextran surface may be used for medical treatment of biofilm associated Candida infections.

  14. Washing effect on superparamagnetic iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Laura-Karina Mireles

    2016-06-01

    Full Text Available Much recent research on nanoparticles has occurred in the biomedical area, particularly in the area of superparamagnetic iron oxide nanoparticles (SPIONs; one such area of research is in their use as magnetically directed prodrugs. It has been reported that nanoscale materials exhibit properties different from those of materials in bulk or on a macro scale [1]. Further, an understanding of the batch-to-batch reproducibility and uniformity of the SPION surface is essential to ensure safe biological applications, as noted in the accompanying article [2], because the surface is the first layer that affects the biological response of the human body. Here, we consider a comparison of the surface chemistries of a batch of SPIONs, before and after the supposedly gentle process of dialysis in water.

  15. Multiple hearth furnace for reducing iron oxide

    Science.gov (United States)

    Brandon, Mark M [Charlotte, NC; True, Bradford G [Charlotte, NC

    2012-03-13

    A multiple moving hearth furnace (10) having a furnace housing (11) with at least two moving hearths (20) positioned laterally within the furnace housing, the hearths moving in opposite directions and each moving hearth (20) capable of being charged with at least one layer of iron oxide and carbon bearing material at one end, and being capable of discharging reduced material at the other end. A heat insulating partition (92) is positioned between adjacent moving hearths of at least portions of the conversion zones (13), and is capable of communicating gases between the atmospheres of the conversion zones of adjacent moving hearths. A drying/preheat zone (12), a conversion zone (13), and optionally a cooling zone (15) are sequentially positioned along each moving hearth (30) in the furnace housing (11).

  16. Modified iron oxide nanomaterials: Functionalization and application

    International Nuclear Information System (INIS)

    Bagheri, Samira; Julkapli, Nurhidayatullaili Muhd

    2016-01-01

    Iron oxide magnetic nanoparticles have aroused the interest of researchers of materials' chemistry due to its exceptional properties such as decent magnetic, electric, catalytic, biocompatibility, and low toxicity. However, these magnetic nanoparticles are predisposed towards aggregation and forming larger particles, due to its strong anisotropic dipolar interactions, particularly in the aqueous phase, consequently depriving them of dispersibility and particular properties, ultimately degrading their performance. Hence, this review focuses on modified magnetic nanoparticles that are stable, easily synthesized, possess a high surface area and could be facile-separated via magnetic forces, and are of low toxicity and costs for applications such as catalyst/catalyst support, food security, biomedical, and pollutant remediation. - Highlights: • Nanomagnetite is interesting due to its exceptional properties. • Nanomagnetite is predisposed towards aggregation and forming larger particles. • Modified nanomagnetite are stable, easily synthesized, possess high surface area. • Modified nanomagnetite got applications as catalyst/catalyst support.

  17. Modified iron oxide nanomaterials: Functionalization and application

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, Samira; Julkapli, Nurhidayatullaili Muhd

    2016-10-15

    Iron oxide magnetic nanoparticles have aroused the interest of researchers of materials' chemistry due to its exceptional properties such as decent magnetic, electric, catalytic, biocompatibility, and low toxicity. However, these magnetic nanoparticles are predisposed towards aggregation and forming larger particles, due to its strong anisotropic dipolar interactions, particularly in the aqueous phase, consequently depriving them of dispersibility and particular properties, ultimately degrading their performance. Hence, this review focuses on modified magnetic nanoparticles that are stable, easily synthesized, possess a high surface area and could be facile-separated via magnetic forces, and are of low toxicity and costs for applications such as catalyst/catalyst support, food security, biomedical, and pollutant remediation. - Highlights: • Nanomagnetite is interesting due to its exceptional properties. • Nanomagnetite is predisposed towards aggregation and forming larger particles. • Modified nanomagnetite are stable, easily synthesized, possess high surface area. • Modified nanomagnetite got applications as catalyst/catalyst support.

  18. Bio-inspired Iron Catalysts for Hydrocarbon Oxidations

    Energy Technology Data Exchange (ETDEWEB)

    Que, Jr., Lawrence [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-03-22

    Stereoselective oxidation of C–H and C=C bonds are catalyzed by nonheme iron enzymes. Inspired by these bioinorganic systems, our group has been exploring the use of nonheme iron complexes as catalysts for the oxidation of hydrocarbons using H2O2 as an environmentally friendly and atom-efficient oxidant in order to gain mechanistic insights into these novel transformations. In particular, we have focused on clarifying the nature of the high-valent iron oxidants likely to be involved in these transformations.

  19. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    Science.gov (United States)

    Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

    2016-11-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

  20. IRON AND FREE RADICAL OXIDATIONS IN CELL MEMBRANES

    Science.gov (United States)

    Schafer, Freya Q.; Yue Qian, Steven; Buettner, Garry R.

    2013-01-01

    Brain tissue being rich in polyunsaturated fatty acids, is very susceptible to lipid peroxidation. Iron is well known to be an important initiator of free radical oxidations. We propose that the principal route to iron-mediated lipid peroxidations is via iron-oxygen complexes rather than the reaction of iron with hydrogen peroxide, the Fenton reaction. To test this hypothesis, we enriched leukemia cells (K-562 and L1210 cells) with docosahexaenoic acid (DHA) as a model for brain tissue, increasing the amount of DHA from approximately 3 mole % to 32 mole %. These cells were then subjected to ferrous iron and dioxygen to initiate lipid peroxidation in the presence or absence of hydrogen peroxide. Lipid-derived radicals were detected using EPR spin trapping with α-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN). As expected, lipid-derived radical formation increases with increasing cellular lipid unsaturation. Experiments with Desferal demonstrate that iron is required for the formation of lipid radicals from these cells. Addition of iron to DHA-enriched L1210 cells resulted in significant amounts of radical formation; radical formation increased with increasing amount of iron. However, the exposure of cells to hydrogen peroxide before the addition of ferrous iron did not increase cellular radical formation, but actually decreased spin adduct formation. These data suggest that iron-oxygen complexes are the primary route to the initiation of biological free radical oxidations. This model proposes a mechanism to explain how catalytic iron in brain tissue can be so destructive. PMID:10872752

  1. Ultrafine ferromagnetic iron oxide nanoparticles: Facile synthesis by low temperature decomposition of iron glycerolate

    Energy Technology Data Exchange (ETDEWEB)

    Bartůněk, Vilém, E-mail: vilem.bartunek@vscht.cz [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Průcha, David [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Švecová, Marie [Department of Analytical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Ulbrich, Pavel [Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Huber, Štěpán; Sedmidubský, David; Jankovský, Ondřej [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic)

    2016-09-01

    We synthesized dark colored ultrafine – sub 10 nm iron oxide nanoparticles by a facile and low temperature process based on thermal decomposition of an affordable precursor – iron glycerolate. Simultaneous thermal analysis (STA) was used to study the thermal behaviour during the decomposition. The iron glycerolate was thoroughly analysed by various methods. The size of the iron nanoparticles was determined from XRD patterns and by transmission electron microscopy (TEM) and their composition has been confirmed by XPS. Magnetic properties of the nanoparticles were studied by vibrating sample magnetometry. The prepared single phase material exhibiting ferromagnetic properties is usable in a wide range of applications and may be suitable even for large scale industrial applications. - Highlights: • Iron glycerolate prepared and characterised. • Iron oxide nanoparticles prepared by thermal decomposition of iron glycerolate. • STA used to study the decomposition. • Products characterised by XRD, XPS, FT-IR, SEM and TEM. • Magnetic behaviour of monophasic samples determined.

  2. Reactive oxygen species-related activities of nano-iron metal and nano-iron oxides.

    Science.gov (United States)

    Wu, Haohao; Yin, Jun-Jie; Wamer, Wayne G; Zeng, Mingyong; Lo, Y Martin

    2014-03-01

    Nano-iron metal and nano-iron oxides are among the most widely used engineered and naturally occurring nanostructures, and the increasing incidence of biological exposure to these nanostructures has raised concerns about their biotoxicity. Reactive oxygen species (ROS)-induced oxidative stress is one of the most accepted toxic mechanisms and, in the past decades, considerable efforts have been made to investigate the ROS-related activities of iron nanostructures. In this review, we summarize activities of nano-iron metal and nano-iron oxides in ROS-related redox processes, addressing in detail the known homogeneous and heterogeneous redox mechanisms involved in these processes, intrinsic ROS-related properties of iron nanostructures (chemical composition, particle size, and crystalline phase), and ROS-related bio-microenvironmental factors, including physiological pH and buffers, biogenic reducing agents, and other organic substances. Copyright © 2014. Published by Elsevier B.V.

  3. Iron oxides and their applications in catalytic processes: a review

    OpenAIRE

    Oliveira, Luiz C. A.; Fabris, José D.; Pereira, Márcio C.

    2013-01-01

    A review of most of the reported studies on the use of iron oxides as catalyst in specific processes, namely Haber-Bosch reaction, Fischer-Tropsch synthesis, Fenton oxidation and photolytic molecular splitting of water to produce gaseous hydrogen, was carried out. An essential overview is thus presented, intending to address the fundamental meaning, as well as the corresponding chemical mechanisms, and perspectives on new technological potentialities of natural and synthetic iron oxides, more...

  4. Body iron is a contributor to oxidative damage of DNA

    DEFF Research Database (Denmark)

    Tuomainen, Tomi-Pekka; Loft, Steffen; Nyyssönen, Kristiina

    2007-01-01

    The transition metal iron is catalytically highly active in vitro, and not surprisingly, body iron has been suggested to promote oxidative stress in vivo. In the current analysis we studied the association of serum ferritin concentration and serum soluble transferrin receptor concentration.......17 (95% CI 0.08-0.26, P = 0.001), and serum soluble transferrin receptor to ferritin concentration ratio (TfR/ferritin) predicted the excretion rate at B = - 0.13 (95% CI - 0.21 to - 0.05, P = 0.002). Our data suggest that body iron contributes to excess oxidative stress already at non-iron overload...

  5. Iron Oxide as an MRI Contrast Agent for Cell Tracking

    Science.gov (United States)

    Korchinski, Daniel J.; Taha, May; Yang, Runze; Nathoo, Nabeela; Dunn, Jeff F.

    2015-01-01

    Iron oxide contrast agents have been combined with magnetic resonance imaging for cell tracking. In this review, we discuss coating properties and provide an overview of ex vivo and in vivo labeling of different cell types, including stem cells, red blood cells, and monocytes/macrophages. Furthermore, we provide examples of applications of cell tracking with iron contrast agents in stroke, multiple sclerosis, cancer, arteriovenous malformations, and aortic and cerebral aneurysms. Attempts at quantifying iron oxide concentrations and other vascular properties are examined. We advise on designing studies using iron contrast agents including methods for validation. PMID:26483609

  6. Magnetization measurements and XMCD studies on ion irradiated iron oxide and core-shell iron/iron-oxide nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Maninder; Qiang, You; Jiang, Weilin; Pearce, Carolyn; McCloy, John S.

    2014-12-02

    Magnetite (Fe3O4) and core-shell iron/iron-oxide (Fe/Fe3O4) nanomaterials prepared by a cluster deposition system were irradiated with 5.5 MeV Si2+ ions and the structures determined by x-ray diffraction as consisting of 100% magnetite and 36/64 wt% Fe/FeO, respectively. However, x-ray magnetic circular dichroism (XMCD) indicates similar surfaces in the two samples, slightly oxidized and so having more Fe3+ than the expected magnetite structure, with XMCD intensity much lower for the irradiated core-shell samples indicating weaker magnetism. X-ray absorption spectroscopy (XAS) data lack the signature for FeO, but the irradiated core-shell system consists of Fe-cores with ~13 nm of separating oxide crystallite, so it is likely that FeO exists deeper than the probe depth of the XAS (~5 nm). Exchange bias (Hex) for both samples becomes increasingly negative as temperature is lowered, but the irradiated Fe3O4 sample shows greater sensitivity of cooling field on Hex. Loop asymmetries and Hex sensitivities of the irradiated Fe3O4 sample are due to interfaces and interactions between grains which were not present in samples before irradiation as well as surface oxidation. Asymmetries in the hysteresis curves of the irradiated core/shell sample are related to the reversal mechanism of the antiferromagnetic FeO and possibly some near surface oxidation.

  7. Selectivity and Activity of Iron Molybdate Catalysts in Oxidation of Methanol

    Directory of Open Access Journals (Sweden)

    Khalid Khazzal Hummadi

    2009-06-01

    Full Text Available The selectivity and activity of iron molybdate catalysts prepared by different methods are compared with those of a commercial catalyst in the oxidation of methanol to formaldehyde in a continuous tubular bed reactor at 200-350 oC (473-623 oK, 10 atm (1013 kPa, with a methanol-oxygen mixture fixed at 5.5% by volume methanol: air ratio. The iron(III molybdate catalyst prepared by co-precipitation and filtration had a selectivity towards formaldehyde in methanol oxidation comparable with a commercial catalyst; maximum selectivity (82.3% was obtained at 573oK when the conversion was 59.7%. Catalysts prepared by reacting iron (III and molybdate by kneading or precipitation followed by evaporation, omitting a filtration stage, were less active and less selective. The selectivity-activity relationships of these catalysts as a function of temperature were discussed in relation to the method of preparation, surface areas and composition. By combing this catalytic data with data from the patent literature we demonstrate a synergy between iron and molybdenum in regard to methanol oxidation to formaldehyde; the optimum composition corresponded to an iron mole fraction 0.2-0.3. The selectivity to formaldehyde was practically constant up to an iron mole fraction 0.3 and then decreased at higher iron concentrations. The iron component can be regarded as the activity promoter. The iron molybdate catalysts can thus be related to other two-component MoO3-based selective oxidation catalysts, e.g. bismuth and cobalt molybdates. The iron oxide functions as a relatively basic oxide abstracting, in the rate-controlling step, a proton from the methyl of a bound methoxy group of chemisorbed methanol. It was proposed that a crucial feature of the sought after iron(III molybdate catalyst is the presence of -O-Mo-O-Fe-O-Mo-O- groups as found in the compound Fe2(MoO43 and for Fe3+ well dispersed in MoO3 generally. At the higher iron(III concentrations the loss of

  8. Phosphorus Retention (32P) by synthetic iron oxides

    International Nuclear Information System (INIS)

    Bittencourt, V.C.; Montanheiro, M.N.S.

    1975-02-01

    The P retention by iron oxides was characterized as a chemical adsorption process followed by a physical adsorption. The former process was very intense with initial amounts of added P but after a certain surface saturation is reached physical interaction occurs. It was supposed that the chemically adsorbed phosphate confers a negative charge on the iron oxides particles, which repels any further physical adsorbtion of the anion. However due to diffusion of phosphate ions into the internal layers of the iron oxides, their surface can retain further amounts of P [pt

  9. REFINERY STAGE OF OXIDES RESTORATION IN ROTATIONAL FURNACES

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2012-01-01

    Full Text Available The article is devoted to research of process of the iron-containing waste recycling in rotary tilting furnaces, in particular, to the phenomenon of formation of ball iron at transition from hard-phase to liquid-phase stage of iron restoration from scale.

  10. High rate flame synthesis of highly crystalline iron oxide nanorods

    International Nuclear Information System (INIS)

    Merchan-Merchan, W; Taylor, A M; Saveliev, A V

    2008-01-01

    Single-step flame synthesis of iron oxide nanorods is performed using iron probes inserted into an opposed-flow methane oxy-flame. The high temperature reacting environment of the flame tends to convert elemental iron into a high density layer of iron oxide nanorods. The diameters of the iron oxide nanorods vary from 10 to 100 nm with a typical length of a few microns. The structural characterization performed shows that nanorods possess a highly ordered crystalline structure with parameters corresponding to cubic magnetite (Fe 3 O 4 ) with the [100] direction oriented along the nanorod axis. Structural variations of straight nanorods such as bends, and T-branched and Y-branched shapes are frequently observed within the nanomaterials formed, opening pathways for synthesis of multidimensional, interconnected networks

  11. Oxidative Stress and the Homeodynamics of Iron Metabolism

    Science.gov (United States)

    Bresgen, Nikolaus; Eckl, Peter M.

    2015-01-01

    Iron and oxygen share a delicate partnership since both are indispensable for survival, but if the partnership becomes inadequate, this may rapidly terminate life. Virtually all cell components are directly or indirectly affected by cellular iron metabolism, which represents a complex, redox-based machinery that is controlled by, and essential to, metabolic requirements. Under conditions of increased oxidative stress—i.e., enhanced formation of reactive oxygen species (ROS)—however, this machinery may turn into a potential threat, the continued requirement for iron promoting adverse reactions such as the iron/H2O2-based formation of hydroxyl radicals, which exacerbate the initial pro-oxidant condition. This review will discuss the multifaceted homeodynamics of cellular iron management under normal conditions as well as in the context of oxidative stress. PMID:25970586

  12. Ca alginate as scaffold for iron oxide nanoparticles synthesis

    Directory of Open Access Journals (Sweden)

    P. V. Finotelli

    2008-12-01

    Full Text Available Recently, nanotechnology has developed to a stage that makes it possible to process magnetic nanoparticles for the site-specific delivery of drugs. To this end, it has been proposed as biomaterial for drug delivery system in which the drug release rates would be activated by a magnetic external stimuli. Alginate has been used extensively in the food, pharmaceutical and biomedical industries for their gel forming properties in the presence of multivalent cations. In this study, we produced iron oxide nanoparticles by coprecipitation of Fe(III and Fe(II. The nanoparticles were entrapped in Ca alginate beads before and after alginate gelation. XRD analysis showed that particles should be associated to magnetite or maghemite with crystal size of 9.5 and 4.3 nm, respectively. Studies using Mössbauer spectroscopy corroborate the superparamagnetic behavior. The combination of magnetic properties and the biocompatibility of alginate suggest that this biomaterial may be used as biomimetic system.

  13. Hydrothermal oxidation in the Biwabik Iron Formation, MN, USA

    Science.gov (United States)

    Losh, Steven; Rague, Ryan

    2018-02-01

    Precambrian iron formations throughout the world, notably in Australia, Brazil, and South Africa, show evidence of hypogene (≥ 110 °C, mostly > 250 °C) oxidation, alteration, and silica dissolution as a result of tectonic or magmatic activity. Although hydrothermal oxidation has been proposed for the prototype Lake Superior-type iron formation, the Biwabik Iron Formation in Minnesota (USA), it has not been documented there. By examining oxidized and unoxidized Biwabik Iron Formation in three mines, including material from high-angle faults that are associated with oxidation, we document an early hypogene oxidation event ( 175 °C) involving medium-salinity aqueous fluids (8.4 ± 4.9 wt% NaCl equiv) that infiltrated iron formation along high-angle faults. At the Hibbing Taconite Mine, hydrothermal fluids oxidized iron carbonates and silicates near faults, producing goethite ± quartz. In contrast with much of the oxidized iron ores on the Mesabi Range, silica was not removed but rather recrystallized during this event, perhaps lying in a rock-dominated system at low cumulative fluid flux. During the hydrothermal oxidation event in the Hibbing Taconite deposit, quartz-filled microfractures and irregular inclusions commonly formed in coarse variably oxidized magnetite, currently the ore mineral: these inclusions degrade the ore by introducing excess silica in magnetic concentrate. Hydrothermal oxidation at Hibbing Taconite Mine is overprinted by later, relatively minor supergene oxidation both along faults and near the surface, which locally dissolved quartz. At the Fayal Reserve Mine, widespread silicate and carbonate gangue dissolution and iron oxidation was followed by precipitation of pyrite, Mn-siderite, apatite, and other minerals in void spaces, which prevented post-oxidation compaction and significant volume loss in the sampled rocks. Although definitive temperature data for this assemblage are needed, the weight of evidence indicates that this

  14. Manganese and iron oxidation by fungi isolated from building stone.

    Science.gov (United States)

    de la Torre, M A; Gomez-Alarcon, G

    1994-01-01

    Acid and nonacid generating fungal strains isolated from weathered sandstone, limestone, and granite of Spanish cathedrals were assayed for their ability to oxidize iron and manganese. In general, the concentration of the different cations present in the mineral salt media directly affected Mn(IV) oxide formation, although in some cases, the addition of glucose and nitrate to the culture media was necessary. Mn(II) oxidation in acidogenic strains was greater in a medium containing the highest concentrations of glucose, nitrate, and manganese. High concentrations of Fe(II), glucose, and mineral salts were optimal for iron oxidation. Mn(IV) precipitated as oxides or hydroxides adhered to the mycelium. Most of the Fe(III) remained in solution by chelation with organic acids excreted by acidogenic strains. Other metabolites acted as Fe(III) chelators in nonacidogenic strains, although Fe(III) deposits around the mycelium were also detected. Both iron and manganese oxidation were shown to involve extracellular, hydrosoluble enzymes, with maximum specific activities during exponential growth. Strains able to oxidize manganese were also able to oxidize iron. It is concluded that iron and manganese oxidation reported in this work were biologically induced by filamentous fungi mainly by direct (enzymatic) mechanisms.

  15. Preparation and characterization of polyindole - iron oxide nanocomposite electrolyte

    International Nuclear Information System (INIS)

    Rajasudha, G.; Stephen, A.; Narayanan, V.

    2009-01-01

    Full text: A novel polyindole-iron oxide containing LiClO 4 solid polymer electrolyte has been prepared. The diverse property of magnetic nanoparticle has elicited wide interest from the point of view of technological applications. Their properties are known to be strongly dependent on size, anisotropy and inter particle interactions. The proton conducting materials has received considerable attention as electrolyte materials in technological applications such as fuel cells, sensors and electrochromic display. In this work, polyindole-iron oxide nanocomposite containing LiClO 4 was prepared by in situ polymerization. The indole was polymerized in the presence of iron oxide, using ammonium peroxy disulphate as an oxidizing agent. The polyindole-iron oxide nanocomposite was characterized by XRD, IR, SEM, TGA and TEM. The iron oxide nano particles was incorporated into polyindole and was confirmed by XRD and Fourier transform infrared (FTIR) spectroscopy. The surface Morphology and thermal stability were studied by thermogravimetric analysis (TGA) and SEM respectively. The ionic conductivity of polyindole electrolyte was analyzed from impedance spectrum. The prepared polyindole-iron oxide nanocomposite could be used as solid electrolyte in lithium ion batteries

  16. Selectivity in the oxidative dehydrogenation of butene on zinc-iron oxide catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kung, H.H.; Kundalkar, B.; Kung, M.C.; Cheng, W.H.

    1980-02-21

    Adsorption, temperature-programed desorption, and pulse reaction studies of cis-2-butene and butadiene on spinel zinc ferrite by previously described methods provided evidence that the selectivity for oxidative dehydrogenation of butenes increases when zinc is added to the iron oxide catalyst because selective oxidation and complete oxidation proceed on separate sites, as they do on pure iron; because the density of sites for selective oxidation is higher and the density of sites for complete combustion is lower than on pure iron oxide; and because the activity of the combustion sites is lower.

  17. Serum Iron and Nitric Oxide Production in Trypanosoma brucei ...

    African Journals Online (AJOL)

    JTEkanem

    reduction in the serum iron status and a modulation of nitric oxide synthase activity of T. brucei infected rats. ... inflammation and tissue damage15. ... The serum iron level was determined ... concentration or of total nitrate and nitrite ... 15. 16. 17. 18. Days. S e ru m iro n lev e l mg. /ml. Infected treated. Infected untreated. 0.

  18. Composition of MBE-grown iron oxide films

    NARCIS (Netherlands)

    Voogt, F.C; Hibma, T; Smulders, P.J M; Niesen, L

    A wide range of iron oxides have been grown epitaxially on MgO(100) substrates using a dual beam technique in which the deposited iron is oxidised by a beam of NO2 particles. At high fluxes magnetite (Fe3-deltaO4) phases with compositions between near-stoichiometric magnetite (Fe3O4, delta = 0) and

  19. Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI) Role

    KAUST Repository

    Mozo, Sergio Lentijo; Zuddas, Efisio; Casu, Alberto; Falqui, Andrea

    2017-01-01

    Controlled synthesis of anisotropic iron oxide nanoparticles is a challenge in the field of nanomaterial research that requires an extreme attention to detail. In particular, following up a previous work showcasing the synthesis of magnetite

  20. Adsorption of trace elements of radionuclides on hydrous iron oxides

    International Nuclear Information System (INIS)

    Music, S.; Ristic, M.

    1988-01-01

    Factors that influence the adsorption of trace elements or radionuclides on hydrous iron oxides were investigated. The adsorption of monovalent cations (Cs + , Rb + ) on hydrous iron oxides is not strongly pH-dependent and it can be regarded as nonspecific. On the other hand, the adsorption of Ag + , divalent cations (Zn 2+ , Cd 2+ , Mn 2+ , Sr 2+ ) or trivalent cations (Cr 3+ , La 3+ , Ce 3+ , Eu 3+ , Gd 3+ , Er 3+ , Yb 3+ ) is strongly pH-dependent. The regularities of the adsorption of these cations on hydrous iron oxides are discussed. The differences in the adsorption behaviour of some divalent and trivalent cations are also explained. Freshly precipitated iron(III) hydroxide can be used for the decontamination of radionuclides from low-level waste solutions. However, the efficacy of decontamination depends on the oxidation state and the chemical properties of radionuclides. (author) 40 refs.; 9 figs

  1. Multiferroic iron oxide thin films at room temperature

    Czech Academy of Sciences Publication Activity Database

    Gich, M.; Fina, I.; Morelli, Alessio; Sánchez, F.; Alexe, M.; Gazquez, J.; Fontcuberta, J.; Roig, A.

    2014-01-01

    Roč. 26, č. 27 (2014), s. 4645-4652 ISSN 0935-9648 Institutional support: RVO:68378271 Keywords : multiferroic * iron oxide * thin film Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 17.493, year: 2014

  2. Synthesis and heating effect of iron/iron oxide composite and iron oxide nanoparticles.

    Science.gov (United States)

    Zeng, Q; Baker, I; Loudis, J A; Liao, Y F; Hoopes, P J

    2007-02-09

    Fe/Fe oxide nanoparticles, in which the core consists of metallic Fe and the shell is composed of Fe oxides, were obtained by reduction of an aqueous solution of FeCl 3 within a NaBH 4 solution, or, using a water-in-oil micro-emulsion with CTAB as the surfactant. The reduction was performed either in an inert atmosphere or in air, and passivation with air was performed to produce the Fe/Fe 3 O 4 core/shell composite. Phase identification and particle size were determined by X-ray diffraction and TEM. Thermal analysis was performed using a differential scanning calorimeter. The quasistatic magnetic properties were measured using a VSM, and the specific absorption rates (SARs) of both Fe oxide and Fe/Fe 3 O 4 composite nanoparticles either dispersed in methanol or in an epoxy resin were measured by Luxtron fiber temperature sensors in an alternating magnetic field of 150 Oe at 250 kHz. It was found that the preparation conditions, including the concentrations of solutions, the mixing procedure and the heat treatment, influence the particle size, the crystal structure and consequently the magnetic properties of the particles. Compared with Fe oxides, the saturation magnetization ( M S ) of Fe/Fe 3 O 4 particles (100-190 emu/g) can be twice as high, and the coercivity ( H C ) can be tunable from several Oe to several hundred Oe. Hence, the SAR of Fe/Fe 3 O 4 composite nanoparticles can be much higher than that of Fe oxides, with a maximum SAR of 345 W/g. The heating behavior is related to the magnetic behavior of the nanoparticles.

  3. Sulfidation of alumina-supported iron and iron-molybdenum oxide catalysts

    NARCIS (Netherlands)

    Ramselaar, W.L.T.M.; Crajé, M.W.J.; Hadders, R.H.; Gerkema, E.; Beer, de V.H.J.; Kraan, van der A.M.

    1990-01-01

    The transition of alumina-supported iron and iron-molybdenum catalysts from the oxidic precursor to the sulfided catalysts was systematically studied by means of in-situ Mössbauer spectroscopy at room temperature. This enabled the adjudgement of various sulfidic phases in the sulfided catalysts. The

  4. Genomic insights into microbial iron oxidation and iron uptake strategies in extremely acidic environments.

    Science.gov (United States)

    Bonnefoy, Violaine; Holmes, David S

    2012-07-01

    This minireview presents recent advances in our understanding of iron oxidation and homeostasis in acidophilic Bacteria and Archaea. These processes influence the flux of metals and nutrients in pristine and man-made acidic environments such as acid mine drainage and industrial bioleaching operations. Acidophiles are also being studied to understand life in extreme conditions and their role in the generation of biomarkers used in the search for evidence of existing or past extra-terrestrial life. Iron oxidation in acidophiles is best understood in the model organism Acidithiobacillus ferrooxidans. However, recent functional genomic analysis of acidophiles is leading to a deeper appreciation of the diversity of acidophilic iron-oxidizing pathways. Although it is too early to paint a detailed picture of the role played by lateral gene transfer in the evolution of iron oxidation, emerging evidence tends to support the view that iron oxidation arose independently more than once in evolution. Acidic environments are generally rich in soluble iron and extreme acidophiles (e.g. the Leptospirillum genus) have considerably fewer iron uptake systems compared with neutrophiles. However, some acidophiles have been shown to grow as high as pH 6 and, in the case of the Acidithiobacillus genus, to have multiple iron uptake systems. This could be an adaption allowing them to respond to different iron concentrations via the use of a multiplicity of different siderophores. Both Leptospirillum spp. and Acidithiobacillus spp. are predicted to synthesize the acid stable citrate siderophore for Fe(III) uptake. In addition, both groups have predicted receptors for siderophores produced by other microorganisms, suggesting that competition for iron occurs influencing the ecophysiology of acidic environments. Little is known about the genetic regulation of iron oxidation and iron uptake in acidophiles, especially how the use of iron as an energy source is balanced with its need to take up

  5. High pressure Moessbauer spectroscopy of perovskite iron oxide

    CERN Document Server

    Nasu, S; Morimoto, S; Kawakami, T; Kuzushita, K; Takano, M

    2003-01-01

    High-pressure sup 5 sup 7 Fe Moessbauer spectroscopy using a diamond anvil cell has been performed for perovskite iron oxides SrFeO sub 3 , CaFeO sub 3 and La sub 1 sub / sub 3 Sr sub 2 sub / sub 3 O sub 3. The charge states and the magnetic dependency to pressure were determined. Pressure magnetic phase diagrams of these perovskite iron oxides are determined up to about 70 GPa. To be clear the magnetic ordered state, they are measured up to 7.8 T external magnetic fields at 4.5K. The phase transition of these perovskite oxides to ferromagnetisms with high magnetic ordered temperature is observed. In higher pressure, high spin-low spin transition of oxides besides CaFeO sub 3 is generated. The feature of Moessbauer spectroscopy, perovskite iron oxide and Moessbauer spectroscopy under high pressure are explained. (S.Y.)

  6. High pressure Moessbauer spectroscopy of perovskite iron oxide

    International Nuclear Information System (INIS)

    Nasu, Saburo; Suenaga, Tomoya; Morimoto, Shotaro; Kawakami, Takateru; Kuzushita, Kaori; Takano, Mikio

    2003-01-01

    High-pressure 57 Fe Moessbauer spectroscopy using a diamond anvil cell has been performed for perovskite iron oxides SrFeO 3 , CaFeO 3 and La 1/3 Sr 2/3 O 3 . The charge states and the magnetic dependency to pressure were determined. Pressure magnetic phase diagrams of these perovskite iron oxides are determined up to about 70 GPa. To be clear the magnetic ordered state, they are measured up to 7.8 T external magnetic fields at 4.5K. The phase transition of these perovskite oxides to ferromagnetisms with high magnetic ordered temperature is observed. In higher pressure, high spin-low spin transition of oxides besides CaFeO 3 is generated. The feature of Moessbauer spectroscopy, perovskite iron oxide and Moessbauer spectroscopy under high pressure are explained. (S.Y.)

  7. Iron(III) species formed during iron(II) oxidation and iron-core formation in bacterioferritin of Escherichia coli

    International Nuclear Information System (INIS)

    Hawkins, C.; Treffry, A.; Mackey, J.; Williams, J.M.; Andrews, S.C.; Guest, J.R.; Harrison, P.M.

    1996-01-01

    This paper describes a preliminary investigation of the mechanisms of Fe(II) oxidation and storage of Fe(III) in the bacterioferritin of Escherichia coli (EcBFR). Using Moessbauer spectroscopy to examine the initial oxidation of iron by EcBFR it is confirmed that this ferritin exhibits 'ferroxidase' activity and is shown that dimeric and monomeric iron species are produced as intermediates. The characteristics of ferroxidase activity in EcBFR is compare d with those of human H-chain ferritin (HuHF) and discuss the different Moessbauer parameters of their dimeric iron with reference to the structures of their di-metal sites. In addition, it is presented preliminary findings suggesting that after an initial 'burst', the rate of oxidation is greatly reduced, possibly due to blockage of the ferroxidase centre by bound iron. A new component, not found in HuHF and probably representing a small cluster of Fe(III) atoms, is reported

  8. Stem cell tracking using iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Bull E

    2014-03-01

    Full Text Available Elizabeth Bull,1 Seyed Yazdan Madani,1 Roosey Sheth,1 Amelia Seifalian,1 Mark Green,2 Alexander M Seifalian1,31UCL Centre for Nanotechnology and Regenerative Medicine, Division of Surgery and Interventional Science, University College London, London, 2Department of Physics, King’s College London, Strand Campus, London, UK; 3Royal Free London National Health Service Foundation Trust Hospital, London, UKAbstract: Superparamagnetic iron oxide nanoparticles (SPIONs are an exciting advancement in the field of nanotechnology. They expand the possibilities of noninvasive analysis and have many useful properties, making them potential candidates for numerous novel applications. Notably, they have been shown that they can be tracked by magnetic resonance imaging (MRI and are capable of conjugation with various cell types, including stem cells. In-depth research has been undertaken to establish these benefits, so that a deeper level of understanding of stem cell migratory pathways and differentiation, tumor migration, and improved drug delivery can be achieved. Stem cells have the ability to treat and cure many debilitating diseases with limited side effects, but a main problem that arises is in the noninvasive tracking and analysis of these stem cells. Recently, researchers have acknowledged the use of SPIONs for this purpose and have set out to establish suitable protocols for coating and attachment, so as to bring MRI tracking of SPION-labeled stem cells into common practice. This review paper explains the manner in which SPIONs are produced, conjugated, and tracked using MRI, as well as a discussion on their limitations. A concise summary of recently researched magnetic particle coatings is provided, and the effects of SPIONs on stem cells are evaluated, while animal and human studies investigating the role of SPIONs in stem cell tracking will be explored.Keywords: stem cells, nanoparticle, magnetic

  9. One step paired electrochemical synthesis of iron and iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Ordoukhanian Juliet

    2016-09-01

    Full Text Available In this study, a new one step paired electrochemical method is developed for simultaneous synthesis of iron and iron oxide nanoparticles. iron and iron oxide are prepared as cathodic and anodic products from iron (ii sulfate aqueous solution in a membrane divided electrolytic cell by the pulsed current electrosynthesis. Because of organic solvent-free and electrochemical nature of the synthesis, the process could be considered as green and environmentally friendly. The reduction of energy consumption and low cost are the other significant advantages of this new method that would have a great application potential in the chemical industry. The nanostructure of prepared samples was characterized by Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The magnetic properties were studied by vibrating sample magnetometer (VsM.

  10. Body iron is a contributor to oxidative damage of DNA

    DEFF Research Database (Denmark)

    Tuomainen, T.P.; Loft, Steffen Huitfeldt; Nyyssonen, K.

    2007-01-01

    The transition metal iron is catalytically highly active in vitro, and not surprisingly, body iron has been suggested to promote oxidative stress in vivo. In the current analysis we studied the association of serum ferritin concentration and serum soluble transferrin receptor concentration...... with daily urinary 8-hydroxydeoxyguanosine excretion, a marker of oxidative stress, in 48 mildly dyslipidemic men in East Finland. In multivariate linear regression analyses allowing for age, smoking, body mass index and physical exercise, serum ferritin concentration predicted the excretion rate at B = 0.......17 (95% CI 0.08-0.26, P = 0.001), and serum soluble transferrin receptor to ferritin concentration ratio (TfR/ferritin) predicted the excretion rate at B = - 0.13 (95% CI - 0.21 to - 0.05, P = 0.002). Our data suggest that body iron contributes to excess oxidative stress already at non-iron overload...

  11. Iron accumulation with age, oxidative stress and functional decline.

    Directory of Open Access Journals (Sweden)

    Jinze Xu

    2008-08-01

    Full Text Available Identification of biological mediators in sarcopenia is pertinent to the development of targeted interventions to alleviate this condition. Iron is recognized as a potent pro-oxidant and a catalyst for the formation of reactive oxygen species in biological systems. It is well accepted that iron accumulates with senescence in several organs, but little is known about iron accumulation in muscle and how it may affect muscle function. In addition, it is unclear if interventions which reduced age-related loss of muscle quality, such as calorie restriction, impact iron accumulation. We investigated non-heme iron concentration, oxidative stress to nucleic acids in gastrocnemius muscle and key indices of sarcopenia (muscle mass and grip strength in male Fischer 344 X Brown Norway rats fed ad libitum (AL or a calorie restricted diet (60% of ad libitum food intake starting at 4 months of age at 8, 18, 29 and 37 months of age. Total non-heme iron levels in the gastrocnemius muscle of AL rats increased progressively with age. Between 29 and 37 months of age, the non-heme iron concentration increased by approximately 200% in AL-fed rats. Most importantly, the levels of oxidized RNA in gastrocnemius muscle of AL rats were significantly increased as well. The striking age-associated increase in non-heme iron and oxidized RNA levels and decrease in sarcopenia indices were all attenuated in the calorie restriction (CR rats. These findings strongly suggest that the age-related iron accumulation in muscle contributes to increased oxidative damage and sarcopenia, and that CR effectively attenuates these negative effects.

  12. Stabilization and functionalization of iron oxide nanoparticles for biomedical applications

    Science.gov (United States)

    Amstad, Esther; Textor, Marcus; Reimhult, Erik

    2011-07-01

    Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of research and practical applications in the biomedical field, including magnetic cell labeling separation and tracking, for therapeutic purposes in hyperthermia and drug delivery, and for diagnostic purposes, e.g., as contrast agents for magnetic resonance imaging. These applications require good NP stability at physiological conditions, close control over NP size and controlled surface presentation of functionalities. This review is focused on different aspects of the stability of superparamagnetic iron oxide NPs, from its practical definition to its implementation by molecular design of the dispersant shell around the iron oxide core and further on to its influence on the magnetic properties of the superparamagnetic iron oxide NPs. Special attention is given to the selection of molecular anchors for the dispersant shell, because of their importance to ensure colloidal and functional stability of sterically stabilized superparamagnetic iron oxide NPs. We further detail how dispersants have been optimized to gain close control over iron oxide NP stability, size and functionalities by independently considering the influences of anchors and the attached sterically repulsive polymer brushes. A critical evaluation of different strategies to stabilize and functionalize core-shell superparamagnetic iron oxide NPs as well as a brief introduction to characterization methods to compare those strategies is given.Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of research and practical applications in the biomedical field, including magnetic cell labeling separation and tracking, for therapeutic purposes in hyperthermia and drug delivery, and for diagnostic purposes, e.g., as contrast agents for magnetic resonance imaging. These applications require good NP stability at physiological conditions, close control over NP size and controlled surface

  13. Role of iron oxide impurities in electrocatalysis by multiwall carbon

    Indian Academy of Sciences (India)

    The role of iron oxide impurities in the electrocatalytic properties of multiwall carbon nanotubes (MWCNTs) prepared by catalytic chemical vapour decomposition method (CCVD) is studied in detail. A novel magnetically modified electrodes have been developed by which MWCNTs were immobilized on indium-tin oxide ...

  14. Role of iron oxide impurities in electrocatalysis by multiwall carbon ...

    Indian Academy of Sciences (India)

    The electro-catalytic oxidation of dopamine, and reduction of hydro- gen peroxide have ... herent ferromagnetic properties at room temperature, which have been used to ... tion of ferrocene in ethanol gave iron oxide nanoparticles. (Io-NPs) with an .... anism shows strong dependence on the nature of the elec- trode surface.

  15. Formation and Transformation of Iron Oxide-Kaolinite Associations in the Presence of Iron(II)

    NARCIS (Netherlands)

    Wei, S.Y.; Liu, F.; Feng, X.H.; Tan, W.F.; Koopal, L.K.

    2011-01-01

    Iron oxide-kaolinite associations are important components of tropical and subtropical soils and have significant influence on the physical and chemical properties of soils. In this study, the formation and transformation of Fe oxide-kaolinite associations as a function of pH, temperature, and time

  16. Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water

    Energy Technology Data Exchange (ETDEWEB)

    Gui Minghui; Smuleac, Vasile [University of Kentucky, Department of Chemical and Materials Engineering (United States); Ormsbee, Lindell E. [University of Kentucky, Department of Civil Engineering (United States); Sedlak, David L. [University of California at Berkeley, Department of Civil and Environmental Engineering (United States); Bhattacharyya, Dibakar, E-mail: db@engr.uky.edu [University of Kentucky, Department of Chemical and Materials Engineering (United States)

    2012-05-15

    The potential for using hydroxyl radical (OH{sup Bullet }) reactions catalyzed by iron oxide nanoparticles (NPs) to remediate toxic organic compounds was investigated. Iron oxide NPs were synthesized by controlled oxidation of iron NPs prior to their use for contaminant oxidation (by H{sub 2}O{sub 2} addition) at near-neutral pH values. Cross-linked polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) microfiltration membranes were prepared by in situ polymerization of acrylic acid inside the membrane pores. Iron and iron oxide NPs (80-100 nm) were directly synthesized in the polymer matrix of PAA/PVDF membranes, which prevented the agglomeration of particles and controlled the particle size. The conversion of iron to iron oxide in aqueous solution with air oxidation was studied based on X-ray diffraction, Moessbauer spectroscopy and BET surface area test methods. Trichloroethylene (TCE) was selected as the model contaminant because of its environmental importance. Degradations of TCE and H{sub 2}O{sub 2} by NP surface generated OH{sup Bullet} were investigated. Depending on the ratio of iron and H{sub 2}O{sub 2}, TCE conversions as high as 100 % (with about 91 % dechlorination) were obtained. TCE dechlorination was also achieved in real groundwater samples with the reactive membranes.

  17. Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water

    International Nuclear Information System (INIS)

    Gui Minghui; Smuleac, Vasile; Ormsbee, Lindell E.; Sedlak, David L.; Bhattacharyya, Dibakar

    2012-01-01

    The potential for using hydroxyl radical (OH • ) reactions catalyzed by iron oxide nanoparticles (NPs) to remediate toxic organic compounds was investigated. Iron oxide NPs were synthesized by controlled oxidation of iron NPs prior to their use for contaminant oxidation (by H 2 O 2 addition) at near-neutral pH values. Cross-linked polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) microfiltration membranes were prepared by in situ polymerization of acrylic acid inside the membrane pores. Iron and iron oxide NPs (80–100 nm) were directly synthesized in the polymer matrix of PAA/PVDF membranes, which prevented the agglomeration of particles and controlled the particle size. The conversion of iron to iron oxide in aqueous solution with air oxidation was studied based on X-ray diffraction, Mössbauer spectroscopy and BET surface area test methods. Trichloroethylene (TCE) was selected as the model contaminant because of its environmental importance. Degradations of TCE and H 2 O 2 by NP surface generated OH • were investigated. Depending on the ratio of iron and H 2 O 2 , TCE conversions as high as 100 % (with about 91 % dechlorination) were obtained. TCE dechlorination was also achieved in real groundwater samples with the reactive membranes.

  18. Iron-oxidation processes in an electroflocculation (electrocoagulation) cell

    Energy Technology Data Exchange (ETDEWEB)

    Sasson, Moshe Ben, E-mail: mosheinspain@hotmail.com [Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100 (Israel); Calmano, Wolfgang [Institute of Environmental Technology and Energy Economics, Technical University of Hamburg-Harburg, 21073 Hamburg (Germany); Adin, Avner [Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100 (Israel)

    2009-11-15

    The processes of iron oxidation in an electroflocculation cell were investigated for a pH range of 5-9 and electric currents of 0.05-0.4 A (equivalent current densities of 8.6-69 A/m{sup 2}). At all pH values and electric currents investigated, it was demonstrated and proven that for all practical purposes, the form of iron that dissolves from the anode is Fe{sup 2+} (ferrous). The difference between the amount of theoretical dissolution as calculated by Faraday's law and the amount of observed dissolved iron ions may indicate two phenomena in electrochemical cells. The first is possible dissolution of the anode even without the operation of an electric current; this led to higher theoretical dissolution rates at lower pH. The second is the participation of some of the electrons of the electric current in reactions other than anode dissolution which led to lower theoretical dissolution rates at higher pH. Those other reactions did not lead to an increase in the local oxidation saturation level near the anode and did not affect iron-oxidation rates in the electroflocculation processes. The oxidation rates of the dissolved Fe{sup 2+} (ferrous) to Fe{sup 3+} (ferric) ions in electroflocculation processes were strongly dependent on the pH and were similar to the known oxidation rates of iron in non-electrochemical cells.

  19. Iron-oxidation processes in an electroflocculation (electrocoagulation) cell

    International Nuclear Information System (INIS)

    Sasson, Moshe Ben; Calmano, Wolfgang; Adin, Avner

    2009-01-01

    The processes of iron oxidation in an electroflocculation cell were investigated for a pH range of 5-9 and electric currents of 0.05-0.4 A (equivalent current densities of 8.6-69 A/m 2 ). At all pH values and electric currents investigated, it was demonstrated and proven that for all practical purposes, the form of iron that dissolves from the anode is Fe 2+ (ferrous). The difference between the amount of theoretical dissolution as calculated by Faraday's law and the amount of observed dissolved iron ions may indicate two phenomena in electrochemical cells. The first is possible dissolution of the anode even without the operation of an electric current; this led to higher theoretical dissolution rates at lower pH. The second is the participation of some of the electrons of the electric current in reactions other than anode dissolution which led to lower theoretical dissolution rates at higher pH. Those other reactions did not lead to an increase in the local oxidation saturation level near the anode and did not affect iron-oxidation rates in the electroflocculation processes. The oxidation rates of the dissolved Fe 2+ (ferrous) to Fe 3+ (ferric) ions in electroflocculation processes were strongly dependent on the pH and were similar to the known oxidation rates of iron in non-electrochemical cells.

  20. X-Ray Photoelectron Spectroscopic Characterization of Iron Oxide Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Radu, T., E-mail: Teodora.Radu@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293, Cluj Napoca (Romania); Iacovita, C. [Department of Pharmaceutical Physics-Biophysics, Faculty of Pharmacy, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400349, Cluj-Napoca (Romania); Benea, D. [Faculty of Physics, Babes Bolyai University, 400271, Cluj-Napoca (Romania); Turcu, R. [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293, Cluj Napoca (Romania)

    2017-05-31

    Highlights: • Characterization of three types of iron oxides magnetic nanoparticles. • A correlation between valence band XPS and the degree of iron oxidation is proposed. • Theoretical contributions of Fe in tetragonal and octahedral environment are shown. - Abstract: We report X-ray photoelectron spectroscopy (XPS) results on iron oxide magnetic nanoparticle (Fe{sub 3}O{sub 4}) synthesized using solvothermal reduction in the presence of polyethylene glycol. The magnetite obtained was employed as precursor for the synthesis of γ-Fe{sub 2}O{sub 3} (by oxygen dissociation) which in turn was transformed into α-Fe{sub 2}O{sub 3}. We confirmed the magnetite, maghemite and hematite structure by Fourier Transformed Spectroscopy (FTIR) and X-ray diffraction (XRD). The analysis of the XPS core level and valence band (VB) photoemission spectra for all investigated samples is discussed in terms of the degree of iron oxidation. This is of fundamental importance to better understand the electronic structure of the obtained iron oxide nanoparticles in order to control and improve their quality for specific biomedical applications. Moreover, theoretical band structure calculations are performed for magnetite and the separate contributions of Fe in tetragonal and octahedral environment are shown.

  1. Progress in electrochemical synthesis of magnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Ramimoghadam, Donya; Bagheri, Samira; Hamid, Sharifah Bee Abd

    2014-01-01

    Recently, magnetic iron oxide particles have been emerged as significant nanomaterials due to its extensive range of application in various fields. In this regard, synthesis of iron oxide nanoparticles with desirable properties and high potential applications are greatly demanded. Therefore, investigation on different iron oxide phases and their magnetic properties along with various commonly used synthetic techniques are remarked and thoroughly described in this review. Electrochemical synthesis as a newfound method with unique advantages is elaborated, followed by design approaches and key parameters to control the properties of the iron oxide nanoparticles. Additionally, since the dispersion of iron oxide nanoparticles is as important as its preparation, surface modification issue has been a serious challenge which is comprehensively discussed using different surfactants. Despite the advantages of the electrochemical synthesis method, this technique has been poorly studied and requires deep investigations on effectual parameters such as current density, pH, electrolyte concentration etc. - Highlights: • IONPs are applied in chemical industries, medicine, magnetic storage etc. • Electrochemical synthesis (EC) is convenient, eco-friendly, selective and low-cost. • EC key factors are current density, pH, electrolyte concentration, electrode type. • Organic, inorganic and biological materials can be used to modify IONPs’ surface. • The physicochemical properties of IONPs can be controlled by adding surfactants

  2. Iron oxide and gold nanoparticles in cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Gotman, Irena, E-mail: gotman@technion.ac.il; Gutmanas, Elazar Y., E-mail: gutmanas@technion.ac.il [Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Psakhie, Sergey G. [Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Lozhkomoev, Aleksandr S. [Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2016-08-02

    Continuous research activities in the field of nanomedicine in the past decade have, to a great extent, been focused on nanoparticle technologies for cancer therapy. Gold and iron oxide nanoparticles (NP) are two of the most studied inorganic nanomaterials due to their unique optical and magnetic properties. Both types of NPs are emerging as promising systems for anti-tumor drug delivery and for nanoparticle-mediated thermal therapy of cancer. In thermal therapy, localized heating inside tumors or in proximity of tumor cells can be induced, for example, with Au NPs by radiofrequency ablation heating or conversion of photon energy (photothermal therapy) and in iron oxide magnetic NPs by heat generation through relaxation in an alternating magnetic field (magnetic hyperthermia). Furthermore, the superparamagnetic properties of iron oxide nanoparticles have led to their use as potent MRI (magnetic resonance imaging) contrast agents. Surface modification/coating can produce NPs with tailored and desired properties, such as enhanced blood circulation time, stability, biocompatibility and water solubility. To target nanoparticles to specific tumor cells, NPs should be conjugated with targeting moieties on the surface which bind to receptors or other molecular structures on the cell surface. The article presents several approaches to enhancing the specificity of Au and iron oxide nanoparticles for tumor tissue by appropriate surface modification/functionalization, as well as the effect of these treatments on the saturation magnetization value of iron oxide NPs. The use of other nanoparticles and nanostructures in cancer treatment is also briefly reviewed.

  3. Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

    International Nuclear Information System (INIS)

    Braga, Tiago P.; Vasconcelos, Igor F.; Sasaki, Jose M.; Fabris, J.D.; Oliveira, Diana Q.L. de; Valentini, Antoninho

    2010-01-01

    Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Moessbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Moessbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.

  4. Whey Peptide-Iron Complexes Increase the Oxidative Stability of Oil-in-Water Emulsions in Comparison to Iron Salts.

    Science.gov (United States)

    Caetano-Silva, Maria Elisa; Barros Mariutti, Lilian Regina; Bragagnolo, Neura; Bertoldo-Pacheco, Maria Teresa; Netto, Flavia Maria

    2018-02-28

    Food fortification with iron may favor lipid oxidation in both food matrices and the human body. This study aimed at evaluating the effect of peptide-iron complexation on lipid oxidation catalyzed by iron, using oil-in-water (O/W) emulsions as a model system. The extent of lipid oxidation of emulsions containing iron salts (FeSO 4 or FeCl 2 ) or iron complexes (peptide-iron complexes or ferrous bisglycinate) was evaluated during 7 days, measured as primary (peroxide value) and secondary products (TBARS and volatile compounds). Both salts catalyzed lipid oxidation, leading to peroxide values 2.6- to 4.6-fold higher than the values found for the peptide-iron complexes. The addition of the peptide-iron complexes resulted in the formation of lower amounts of secondary volatiles of lipid oxidation (up to 78-fold) than those of iron salts, possibly due to the antioxidant activity of the peptides and their capacity to keep iron apart from the lipid phase, since the iron atom is coordinated and takes part in a stable structure. The peptide-iron complexes showed potential to reduce the undesirable sensory changes in food products and to decrease the side effects related to free iron and the lipid damage of cell membranes in the organism, due to the lower reactivity of iron in the complexed form.

  5. Methods of preparing deposits containing iron oxides for recycling

    Directory of Open Access Journals (Sweden)

    T. Lis

    2013-04-01

    Full Text Available The metallurgical industry is one of the largest sources of wastes. Some of them, however, owing to their content of metals such as zinc or iron, may become valuable secondary raw materials. In order to achieve that purpose, they require appropriate preparation. This article provides a discussion on the methods of preparation of scrap from steelworks, namely deposits containing iron oxides, enabling their recycling.

  6. Purification of Lysosomes Using Supraparamagnetic Iron Oxide Nanoparticles (SPIONs).

    Science.gov (United States)

    Rofe, Adam P; Pryor, Paul R

    2016-04-01

    Lysosomes can be rapidly isolated from tissue culture cells using supraparamagnetic iron oxide particles (SPIONs). In this protocol, colloidal iron dextran (FeDex) particles, a type of SPION, are taken up by cultured mouse macrophage cells via the endocytic pathway. The SPIONs accumulate in lysosomes, the end point of the endocytic pathway, permitting the lysosomes to be isolated magnetically. The purified lysosomes are suitable for in vitro fusion assays or for proteomic analysis. © 2016 Cold Spring Harbor Laboratory Press.

  7. Safety assessment of chronic oral exposure to iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Chamorro, Susana; Vaquero, María Pilar; Brenes, Agustín; Gutiérrez, Lucía; Salas, Gorka; Luengo, Yurena; Verdoy, Dolores; José Teran, Francisco

    2015-01-01

    Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe 2 O 3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe 2 O 3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe 2 O 3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses. (paper)

  8. Magnetic iron oxide for contrast-enhanced MR imaging

    International Nuclear Information System (INIS)

    Fahlvik, A.K.

    1991-05-01

    The main objective of this experimental work has been to study the biological fate and the contrast enhancing potential of a model preparation of magnetic iron oxide (MSM) after intravenous injection to rodents. This was achieved by: Studying in vitro contrast efficacy of various magnetic iron oxide preparations by relaxation analysis. Studying in vivo contrast efficacy of MSM by relaxation analysis and NMR imaging. Studying the biodistribution and bioelimination of MSM in independent experiments using relaxation analysis, radioactivity studies and histological techniques. Studying interactions of MSM with target cells and target organelles using ex vivo techniques. Based on the presented experimental study, the MSM model preparation of magnetic iron oxide seems to fulfill basic requirements of NMR contrast agents: efficient proton relaxation, specific in vivo distribution, and biological tolerance. 177 refs., 5 figs., 2 tabs

  9. Magnetic behavior of iron oxide nanoparticle-biomolecule assembly

    International Nuclear Information System (INIS)

    Kim, Taegyun; Reis, Lynn; Rajan, Krishna; Shima, Mutsuhiro

    2005-01-01

    Iron oxide nanoparticles of 8-20 nm in size were investigated as an assembly with biomolecules synthesized in an aqueous solution. The magnetic behavior of the biomolecule-nanoparticles assembly depends sensitively on the morphology and hence the distribution of the nanoparticles, where the dipole coupling between the nanoparticles governs the overall magnetic behavior. In assemblies of iron oxide nanoparticles with trypsin, we observe a formation of unusual self-alignment of nanoparticles within trypsin molecules. In such an assembly structure, the magnetic particles tend to exhibit a lower spin-glass transition temperature than as-synthesized bare iron oxide nanoparticles probably due to reduced interparticle couplings within the molecular matrix. The observed self-alignment of nanoparticles in biomolecules may be a useful approach for directed nanoparticles assembly

  10. Structural transformations of heat-treated bacterial iron oxide

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Hideki, E-mail: hideki-h@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); JST, CREST, Okayama 700-8530 (Japan); Fujii, Tatsuo [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Kohara, Shinji [Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198 (Japan); Nakanishi, Koji [Office of Society-Academia Collaboration for Innovation, Kyoto University, Uji 611-0011 (Japan); Yogi, Chihiro [SR Center, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan); Peterlik, Herwig [Faculty of Physics, University of Vienna, A-1090 Vienna (Austria); Nakanishi, Makoto [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Takada, Jun [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); JST, CREST, Okayama 700-8530 (Japan)

    2015-04-01

    A bacterial siliceous iron oxide microtubule (diameter: ca. 1 μm, 15Fe{sub 2}O{sub 3}·8SiO{sub 2}·P{sub 2}O{sub 5}·30H{sub 2}O) produced by Leptothrix ochracea was heat treated in air and its structural transformation was investigated in detail by microscopy, diffractometry, and spectroscopy. Although the heat-treated bacterial iron oxide retained its original microtubular structure, its nanoscopic, middle-range, and local structures changed drastically. Upon heat treatment, nanosized pores were formed and their size changed depending on temperature. The Fe–O–Si linkages were gradually cleaved with increasing temperature, causing the progressive separation of Fe and Si ions into iron oxide and amorphous silicate phases, respectively. Concomitantly, global connectivity and local structure of FeO{sub 6} octahedra in the iron oxide nanoparticles systematically changed depending on temperature. These comprehensive investigations clearly revealed various structural changes of the bacterial iron oxide which is an important guideline for the future exploration of novel bio-inspired materials. - Highlights: • Structural transformation of a bacterial iron oxide microtubule was investigated. • Si–O–Fe was cleaved with increasing temperature to form α-Fe{sub 2}O{sub 3}/silicate composite. • Crystallization to 2Fh started at 500 °C to give α-Fe{sub 2}O{sub 3} >700 °C. • FeO{sub 6} octahedra were highly distorted <500 °C. • Formation of face-sharing FeO{sub 6} was promoted >500 °C, releasing the local strain of FeO{sub 6}.

  11. Elucidation of the electrochromic mechanism of nanostructured iron oxides films

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Lobato, M.A.; Martinez, Arturo I.; Castro-Roman, M. [Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav Campus Saltillo, Carr. Saltillo-Monterrey Km. 13, Ramos Arizpe, Coah. 25900 (Mexico); Perry, Dale L. [Mail Stop 70A1150, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Zarate, R.A. [Departamento de Fisica, Facultad de Ciencias, Universidad Catolica del Norte, Casilla 1280, Antofagasta (Chile); Escobar-Alarcon, L. (Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico)

    2011-02-15

    Nanostructured hematite thin films were electrochemically cycled in an aqueous solution of LiOH. Through optical, structural, morphological, and magnetic measurements, the coloration mechanism of electrochromic iron oxide thin films was elucidated. The conditions for double or single electrochromic behavior are given in this work. During the electrochemical cycling, it was found that topotactic transformations of hexagonal crystal structures are favored; i.e. {alpha}-Fe{sub 2}O{sub 3} to Fe(OH){sub 2} and subsequently to {delta}-FeOOH. These topotactic redox reactions are responsible for color changes of iron oxide films. (author)

  12. Effect of surfactant for magnetic properties of iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Haracz, S. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Hilgendorff, M. [Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany); Rybka, J.D. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Giersig, M. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany)

    2015-12-01

    Highlights: • Dynamic behavior of magnetic nanoparticles. • Synthesis of iron oxide nanoparticles. • Effect of surfactant for magnetic properties. - Abstract: For different medical applications nanoparticles (NPs) with well-defined magnetic properties have to be used. Coating ligand can change the magnetic moment on the surface of nanostructures and therefore the magnetic behavior of the system. Here we investigated magnetic NPs in a size of 13 nm conjugated with four different kinds of surfactants. The surface anisotropy and the magnetic moment of the system were changed due to the presence of the surfactant on the surface of iron oxide NPs.

  13. Recovery of iron oxide from coal fly ash

    Science.gov (United States)

    Dobbins, Michael S.; Murtha, Marlyn J.

    1983-05-31

    A high quality iron oxide concentrate, suitable as a feed for blast and electric reduction furnaces is recovered from pulverized coal fly ash. The magnetic portion of the fly ash is separated and treated with a hot strong alkali solution which dissolves most of the silica and alumina in the fly ash, leaving a solid residue and forming a precipitate which is an acid soluble salt of aluminosilicate hydrate. The residue and precipitate are then treated with a strong mineral acid to dissolve the precipitate leaving a solid residue containing at least 90 weight percent iron oxide.

  14. Electrolytic photodissociation of chemical compounds by iron oxide electrodes

    Science.gov (United States)

    Somorjai, Gabor A.; Leygraf, Christofer H.

    1984-01-01

    Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor diode having visible light as its sole source of energy. The diode consists of low cost, readily available materials, specifically polycrystalline iron oxide doped with silicon in the case of the n-type semi-conductor electrode, and polycrystalline iron oxide doped with magnesium in the case of the p-type electrode. So long as the light source has an energy greater than 2.2 electron volts, no added energy source is needed to achieve dissociation.

  15. Microbial Oxidation of Iron Sulfides in Anaerobic Environments

    DEFF Research Database (Denmark)

    Vaclavkova, Sarka

    Abstract (shortened): Iron sulfides (FeSx), representing 0.04-10 % of Danish dry soil weight, oxidize in a presence of oxygen, releasing sulfuric acid and free iron. Environmental impact of FeSx oxidation is commonly seen on agricultural sites cultivated by drainage as acid sulfate soil formation....... MISON was found to count for about 1/3 of the net NO3- reduction in MISON active environments, despite the presence of alternative electron donor, organic carbon. The rate of MISON was found to be dependent on the available reactive surface area of FeSx and on the microorganism involved. The findings...

  16. Transformation of vivianite by anaerobic nitrate-reducing iron-oxidizing bacteria.

    Science.gov (United States)

    Miot, J; Benzerara, K; Morin, G; Bernard, S; Beyssac, O; Larquet, E; Kappler, A; Guyot, F

    2009-06-01

    In phosphate-rich environments, vivianite (Fe(II)(3)(PO(4))(2), 8H(2)O) is an important sink for dissolved Fe(II) and is considered as a very stable mineral due to its low solubility at neutral pH. In the present study, we report the mineralogical transformation of vivianite in cultures of the nitrate-reducing iron-oxidizing bacterial strain BoFeN1 in the presence of dissolved Fe(II). Vivianite was first transformed into a greenish phase consisting mostly of an amorphous mixed valence Fe-phosphate. This precipitate became progressively orange and the final product of iron oxidation consisted of an amorphous Fe(III)-phosphate. The sub-micrometer analysis by scanning transmission X-ray microscopy of the iron redox state in samples collected at different stages of the culture indicated that iron was progressively oxidized at the contact of the bacteria and at a distance from the cells in extracellular minerals. Iron oxidation in the extracellular minerals was delayed by a few days compared with cell-associated Fe-minerals. This led to strong differences of Fe redox in between these two types of minerals and finally to local heterogeneities of redox within the sample. In the absence of dissolved Fe(II), vivianite was not significantly transformed by BoFeN1. Whereas Fe(II) oxidation at the cell contact is most probably directly catalyzed by the bacteria, vivianite transformation at a distance from the cells might result from oxidation by nitrite. In addition, processes leading to the export of Fe(III) from bacterial oxidation sites to extracellular minerals are discussed including some involving colloids observed by cryo-transmission electron microscopy in the culture medium.

  17. Unprecedented Selective Oxidation of Styrene Derivatives using a Supported Iron Oxide Nanocatalyst in Aqueous Medium

    Science.gov (United States)

    Iron oxide nanoparticles supported on mesoporous silica-type materials have been successfully utilized in the aqueous selective oxidation of alkenes under mild conditions using hydrogen peroxide as a green oxidant. Catalysts could be easily recovered after completion of the reac...

  18. DETERMINATION OF THE RATES AND PRODUCTS OF FERROUS IRON OXIDATION IN ARSENIC-CONTAMINATED POND WATER.

    Science.gov (United States)

    Dissolved ferrous iron and arsenic in the presence of insufficient oxygenated ground water is released into a pond. When the mixing of ferrous iron and oxygenated water within the pond occurs, the ferrous iron is oxidized and precipitated as an iron oxide. Groups of experiments...

  19. Synthesis, characterization, applications, and challenges of iron oxide nanoparticles

    Science.gov (United States)

    Ali, Attarad; Zafar, Hira; Zia, Muhammad; ul Haq, Ihsan; Phull, Abdul Rehman; Ali, Joham Sarfraz; Hussain, Altaf

    2016-01-01

    Recently, iron oxide nanoparticles (NPs) have attracted much consideration due to their unique properties, such as superparamagnetism, surface-to-volume ratio, greater surface area, and easy separation methodology. Various physical, chemical, and biological methods have been adopted to synthesize magnetic NPs with suitable surface chemistry. This review summarizes the methods for the preparation of iron oxide NPs, size and morphology control, and magnetic properties with recent bioengineering, commercial, and industrial applications. Iron oxides exhibit great potential in the fields of life sciences such as biomedicine, agriculture, and environment. Nontoxic conduct and biocompatible applications of magnetic NPs can be enriched further by special surface coating with organic or inorganic molecules, including surfactants, drugs, proteins, starches, enzymes, antibodies, nucleotides, nonionic detergents, and polyelectrolytes. Magnetic NPs can also be directed to an organ, tissue, or tumor using an external magnetic field for hyperthermic treatment of patients. Keeping in mind the current interest in iron NPs, this review is designed to report recent information from synthesis to characterization, and applications of iron NPs. PMID:27578966

  20. The fate of arsenic adsorbed on iron oxides in the presence of arsenite-oxidizing bacteria.

    Science.gov (United States)

    Zhang, Zhennan; Yin, Naiyi; Du, Huili; Cai, Xiaolin; Cui, Yanshan

    2016-05-01

    Arsenic (As) is a redox-active metalloid whose toxicity and mobility in soil depend on its oxidation state. Arsenite [As(III)] can be oxidized by microbes and adsorbed by minerals in the soil. However, the combined effects of these abiotic and biotic processes are not well understood. In this study, the fate of arsenic in the presence of an isolated As(III)-oxidizing bacterium (Pseudomonas sp. HN-1, 10(9) colony-forming units (CFUs)·ml(-1)) and three iron oxides (goethite, hematite, and magnetite at 1.6 g L(-1)) was determined using batch experiments. The total As adsorption by iron oxides was lower with bacteria present and was higher with iron oxides alone. The total As adsorption decreased by 78.6%, 36.0% and 79.7% for goethite, hematite and magnetite, respectively, due to the presence of bacteria. As(III) adsorbed on iron oxides could also be oxidized by Pseudomonas sp. HN-1, but the oxidation rate (1.3 μmol h(-1)) was much slower than the rate in the aqueous phase (96.2 μmol h(-1)). Therefore, the results of other studies with minerals only might overestimate the adsorptive capacity of solids in natural systems; the presence of minerals might hinder As(III) oxidation by microbes. Under aerobic conditions, in the presence of iron oxides and As(III)-oxidizing bacteria, arsenic is adsorbed onto iron oxides within the adsorption capacity, and As(V) is the primary form in the solid and aqueous phases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Ceruloplasmin Oxidation, a Feature of Parkinson's Disease CSF, Inhibits Ferroxidase Activity and Promotes Cellular Iron Retention

    KAUST Repository

    Olivieri, S.; Conti, A.; Iannaccone, S.; Cannistraci, C. V.; Campanella, A.; Barbariga, M.; Codazzi, F.; Pelizzoni, I.; Magnani, G.; Pesca, M.; Franciotta, D.; Cappa, S. F.; Alessio, M.

    2011-01-01

    Parkinson's disease is a neurodegenerative disorder characterized by oxidative stress and CNS iron deposition. Ceruloplasmin is an extracellular ferroxidase that regulates cellular iron loading and export, and hence protects tissues from oxidative

  2. Colloidosome-based synthesis of a multifunctional nanostructure of silver and hollow iron oxide nanoparticles

    KAUST Repository

    Pan, Yue; Gao, Jinhao; Zhang, Bei; Zhang, Xixiang; Xu, Bing

    2010-01-01

    nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X

  3. Jasmonate signaling is activated in the very early stages of iron deficiency responses in rice roots.

    Science.gov (United States)

    Kobayashi, Takanori; Itai, Reiko Nakanishi; Senoura, Takeshi; Oikawa, Takaya; Ishimaru, Yasuhiro; Ueda, Minoru; Nakanishi, Hiromi; Nishizawa, Naoko K

    2016-07-01

    Under low iron availability, plants induce the expression of various genes involved in iron uptake and translocation at the transcriptional level. This iron deficiency response is affected by various plant hormones, but the roles of jasmonates in this response are not well-known. We investigated the involvement of jasmonates in rice iron deficiency responses. High rates of jasmonate-inducible genes were induced during the very early stages of iron deficiency treatment in rice roots. Many jasmonate-inducible genes were also negatively regulated by the ubiquitin ligases OsHRZ1 and OsHRZ2 and positively regulated by the transcription factor IDEF1. Ten out of 35 genes involved in jasmonate biosynthesis and signaling were rapidly induced at 3 h of iron deficiency treatment, and this induction preceded that of known iron deficiency-inducible genes involved in iron uptake and translocation. Twelve genes involved in jasmonate biosynthesis and signaling were also upregulated in HRZ-knockdown roots. Endogenous concentrations of jasmonic acid and jasmonoyl isoleucine tended to be rapidly increased in roots in response to iron deficiency treatment, whereas these concentrations were higher in HRZ-knockdown roots under iron-sufficient conditions. Analysis of the jasmonate-deficient cpm2 mutant revealed that jasmonates repress the expression of many iron deficiency-inducible genes involved in iron uptake and translocation under iron sufficiency, but this repression is partly canceled under an early stage of iron deficiency. These results indicate that jasmonate signaling is activated during the very early stages of iron deficiency, which is partly regulated by IDEF1 and OsHRZs.

  4. The production of iron oxide during peridotite serpentinization: Influence of pyroxene

    Directory of Open Access Journals (Sweden)

    Ruifang Huang

    2017-11-01

    orthopyroxene-derived serpentine indicates that aluminum and silica greatly control the production of iron oxide. Based on our results and data from natural serpentinites reported by other workers, we propose that aluminum may be more influential at the early stages of peridotite serpentinization when the production of iron oxide is very low, whereas silica may have a greater control on iron oxide production during the late stages instead.

  5. Red Dawn: Characterizing Iron Oxide Minerals in Atmospheric Dust

    Science.gov (United States)

    Yauk, K.; Ottenfeld, C. F.; Reynolds, R. L.; Goldstein, H.; Cattle, S.; Berquo, T. S.; Moskowitz, B. M.

    2012-12-01

    Atmospheric dust is comprised of many components including small amounts of iron oxide minerals. Although the iron oxides make up a small weight percent of the bulk dust, they are important because of their roles in ocean fertilization, controls on climate, and as a potential health hazard to humans. Here we report on the iron oxide mineralogy in dust from a large dust storm, dubbed Red Dawn, which engulfed eastern Australia along a 3000 km front on 23 September 2009. Red Dawn originated from the lower Lake Eyre Basin of South Australia, western New South Wales (NSW) and southwestern Queensland and was the worst dust storm to have hit the city of Sydney in more than 60 years. Dust samples were collected from various locations across eastern Australia (Lake Cowal, Orange, Hornsby, Sydney) following the Red Dawn event. Our dust collection provides a good opportunity to study the physical and mineralogical properties of iron oxides from Red Dawn using a combination of reflectance spectroscopy, Mössbauer spectroscopy (MB), and magnetic measurements. Magnetization measurements from 20-400 K reveal that magnetite/maghemite, hematite and goethite are present in all samples with magnetite occurring in trace amounts (effects (d< 100 nm). Finally, we compared reflectance with a magnetic parameter (hard isothermal remanent magnetization, HIRM) for ferric oxide abundance to assess the degree to which ferric oxide in these samples might absorb solar radiation. In samples for which both parameters were obtained, HIRM and average reflectance over the visible wavelengths are correlated as a group (r2=0.24). These results indicate that the ferric oxide minerals in Red Dawn dust absorb solar radiation. Much of this ferric oxide occurs likely as grain coatings of nanohematite and nanogoethite, thereby providing high surface area to enhance absorption of solar radiation.

  6. From iron coordination compounds to metal oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Mihail Iacob

    2016-12-01

    Full Text Available Various types, shapes and sizes of iron oxide nanoparticles were obtained depending on the nature of the precursor, preparation method and reaction conditions. The mixed valence trinuclear iron acetate, [Fe2IIIFeIIO(CH3COO6(H2O3]·2H2O (FeAc1, μ3-oxo trinuclear iron(III acetate, [Fe3O(CH3COO6(H2O3]NO3∙4H2O (FeAc2, iron furoate, [Fe3O(C4H3OCOO6(CH3OH3]NO3∙2CH3OH (FeF, iron chromium furoate, FeCr2O(C4H3OCOO6(CH3OH3]NO3∙2CH3OH (FeCrF, and an iron complex with an original macromolecular ligand (FePAZ were used as precursors for the corresponding oxide nanoparticles. Five series of nanoparticle samples were prepared employing either a classical thermal pathway (i.e., thermal decomposition in solution, solvothermal method, dry thermal decomposition/calcination or using a nonconventional energy source (i.e., microwave or ultrasonic treatment to convert precursors into iron oxides. The resulting materials were structurally characterized by wide-angle X-ray diffraction and Fourier transform infrared, Raman, energy-dispersive X-ray, and X-ray fluorescence spectroscopies, as well as thermogravimetric analysis. The morphology was characterized by transmission electron microscopy, atomic force microscopy and dynamic light scattering. The parameters were varied within each route to fine tune the size and shape of the formed nanoparticles.

  7. From iron coordination compounds to metal oxide nanoparticles.

    Science.gov (United States)

    Iacob, Mihail; Racles, Carmen; Tugui, Codrin; Stiubianu, George; Bele, Adrian; Sacarescu, Liviu; Timpu, Daniel; Cazacu, Maria

    2016-01-01

    Various types, shapes and sizes of iron oxide nanoparticles were obtained depending on the nature of the precursor, preparation method and reaction conditions. The mixed valence trinuclear iron acetate, [Fe 2 III Fe II O(CH 3 COO) 6 (H 2 O) 3 ]·2H 2 O (FeAc1), μ 3 -oxo trinuclear iron(III) acetate, [Fe 3 O(CH 3 COO) 6 (H 2 O) 3 ]NO 3 ∙4H 2 O (FeAc2), iron furoate, [Fe 3 O(C 4 H 3 OCOO) 6 (CH 3 OH) 3 ]NO 3 ∙2CH 3 OH (FeF), iron chromium furoate, FeCr 2 O(C 4 H 3 OCOO) 6 (CH 3 OH) 3 ]NO 3 ∙2CH 3 OH (FeCrF), and an iron complex with an original macromolecular ligand (FePAZ) were used as precursors for the corresponding oxide nanoparticles. Five series of nanoparticle samples were prepared employing either a classical thermal pathway (i.e., thermal decomposition in solution, solvothermal method, dry thermal decomposition/calcination) or using a nonconventional energy source (i.e., microwave or ultrasonic treatment) to convert precursors into iron oxides. The resulting materials were structurally characterized by wide-angle X-ray diffraction and Fourier transform infrared, Raman, energy-dispersive X-ray, and X-ray fluorescence spectroscopies, as well as thermogravimetric analysis. The morphology was characterized by transmission electron microscopy, atomic force microscopy and dynamic light scattering. The parameters were varied within each route to fine tune the size and shape of the formed nanoparticles.

  8. Synthesis and characterization of composites of mixed oxides of iron ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 34; Issue 4. Synthesis and characterization of composites of mixed oxides of iron and neodymium in polymer matrix of aniline–formaldehyde. Sajdha H N Sheikh B L Kalsotra N Kumar S Kumar. Volume 34 Issue 4 July 2011 pp 843-851 ...

  9. Structural investigations of biogenic iron oxide samples. Preliminary results

    International Nuclear Information System (INIS)

    Balasoiu, M.; Kuklin, A.I.; Orelovich, O.L.; Kovalev, Yu.S.; Arzumanyan, G.M.; Kurkin, T.S.; Stolyar, S.V.; Iskhakov, R.S.; Rajkher, Yu.L.

    2008-01-01

    Some preliminary results on morphology and structure of iron oxide particles formed inside Klebsiella oxytoca bacteria are presented. In particular, by means of optical microscopy, scanning electron microscopy and small-angle X-ray scattering the effect of the bacteria age (the duration of growth) on the nanoparticles properties is studied

  10. Minerals of oxidation zone of the Chokadambulaq iron deposit

    International Nuclear Information System (INIS)

    Safaraliev, N.S.

    2008-01-01

    The zone of oxidation of Chokadambulaq iron deposit has original mineral composition, which characterized specificity of their formation. Here is formed a secondary zone of enrichment marit ores, having practical meaning. In last is concentrated from 0.5 up to 1.0% from total quantities of reserves

  11. Self-orderding of iron oxide nanoparticles covered by graphene

    Czech Academy of Sciences Publication Activity Database

    Valeš, Václav; Vejpravová, Jana; Pacáková, Barbara; Holý, V.; Bernstorff, S.; Kalbáč, Martin

    2014-01-01

    Roč. 251, č. 12 (2014), s. 2499-2504 ISSN 0370-1972 R&D Projects: GA MŠk LL1301; GA ČR GAP204/10/1677 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : GISAXS * graphene * iron oxide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.489, year: 2014

  12. Iron oxide redox chemistry and nuclear fuel disposal

    International Nuclear Information System (INIS)

    Jobe, D.J.; Lemire, R.J.; Taylor, P.

    1997-04-01

    Solubility and stability data for iron (III) oxides and aqueous Fe(II) and Fe(III) species are reviewed, and selected values are used to calculate potential-pH diagrams for the iron system at temperatures of 25 and 100 deg C, chloride activities {C1 - } = 10 -2 and 1 mol/kg, total carbonate activity {C T } = 10 -3 mol/kg, and iron(III) oxide/oxyhydroxide solubility products (25 deg C values) K sp = {Fe 3+ }{OH - } 3 = 10 -38.5 , 10 -40 and 10 -42 . The temperatures and anion concentrations bracket the range of conditions expected in a Canadian nuclear fuel waste disposal vault. The three solubility products represent a conservative upper limit, a most probable value, and a minimum credible value, respectively, for the iron oxides likely to be important in controlling redox conditions in a disposal vault for CANDU nuclear reactor fuel. Only in the first of these three cases do the calculated redox potentials significantly exceed values under which oxidative dissolution of the fuel may occur. (author)

  13. Growth and properties of epitaxial iron oxide layers

    NARCIS (Netherlands)

    Voogt, F.C; Fujii, T; Hibma, T; Zhang, G.L.; Smulders, P.J M

    1996-01-01

    Epitaxial layers of iron oxides have been grown on a MgO(001) substrate by evaporating natural Fe or Fe-57 from Knudsen cells in the presence of a NO2 flow directed to the substrate. The resulting layers have been investigated in situ with LEED, RHEED, AES and XPS and ex situ with GEMS and ion beam

  14. Sulfidation of carbon-supported iron oxide catalysts

    NARCIS (Netherlands)

    Ramselaar, W.L.T.M.; Hadders, R.H.; Gerkema, E.; Beer, de V.H.J.; Oers, van E.M.; Kraan, van der A.M.

    1989-01-01

    The sulfidation of carbon-supported iron oxide catalysts was studied by means of in-situ Mössbauer spectroscopy at temperatures down to 4.2 K. The catalysts were dried in two different ways and then sulfided in a flow of 10% H2S in H2 at temperatures between 293 and 773 K. Thiophene

  15. Identification of Spinel Iron Oxide Nanoparticles by 57Fe NMR

    Directory of Open Access Journals (Sweden)

    SangGap Lee

    2011-12-01

    Full Text Available We have synthesized and studied monodisperse iron oxide nanoparticles of smaller than 10 nm to identify between the two spinel phases, magnetite and maghemite. It is shown that 57Fe NMR spectroscopy is a promising tool for distinguishing between the two phases.

  16. Thermosensitive liposomes entrapping iron oxide nanoparticles for controllable drug release

    International Nuclear Information System (INIS)

    Tai, L-A; Wang, Y-C; Wang, Y-J; Yang, C-S; Tsai, P-J; Lo, L-W

    2009-01-01

    Iron oxide nanoparticles can serve as a heating source upon alternative magnetic field (AMF) exposure. Iron oxide nanoparticles can be mixed with thermosensitive nanovehicles for hyperthermia-induced drug release, yet such a design and mechanism may not be suitable for controllable drug release applications in which the tissues are susceptible to environmental temperature change such as brain tissue. In the present study, iron oxide nanoparticles were entrapped inside of thermosensitive liposomes for AMF-induced drug release while the environmental temperature was maintained at a constant level. Carboxyfluorescein was co-entrapped with the iron oxide nanoparticles in the liposomes as a model compound for monitoring drug release and environmental temperature was maintained with a water circulator jacket. These experiments have been successfully performed in solution, in phantom and in anesthetized animals. Furthermore, the thermosensitive liposomes were administered into rat forearm skeletal muscle, and the release of carboxylfluorescein triggered by the external alternative magnetic field was monitored by an implanted microdialysis perfusion probe with an on-line laser-induced fluorescence detector. In the future such a device could be applied to simultaneous magnetic resonance imaging and non-invasive drug release in temperature-sensitive applications.

  17. NO Oxidation Kinetics on Iron Zeolites: Influence of Framework Type and Iron Speciation

    Czech Academy of Sciences Publication Activity Database

    Brosius, R.; Habermacher, D.; Martens, J. A.; Vradman, L.; Herskowitz, M.; Čapek, Libor; Sobalík, Zdeněk; Dědeček, Jiří; Wichterlová, Blanka; Tokarová, V.; Gonsiorová, O.

    30-31, 1/4 (2004), s. 333-339 ISSN 1022-5528 Grant - others:AMMONORE G5RD-CT(XE) 2001-00595 Institutional research plan: CEZ:AV0Z4040901 Keywords : NO oxidation * zeolites * iron Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.493, year: 2004

  18. Iron oxide nanotubes synthesized via template-based electrodeposition

    Science.gov (United States)

    Lim, Jin-Hee; Min, Seong-Gi; Malkinski, Leszek; Wiley, John B.

    2014-04-01

    Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition. In the case of magnetite nanotubes, which consist of slightly larger nanoparticles, magnetization curves show ferromagnetism with weak coercivity at room temperature, while FC-ZFC curves exhibit the Verwey transition at 125 K.Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition

  19. Iron Status and Inflammation in Early Stages of Chronic Kidney Disease

    Directory of Open Access Journals (Sweden)

    Ewelina Łukaszyk

    2015-06-01

    Full Text Available Background/Aims: One of the most common causes of anemia of chronic disease (ACD is chronic kidney disease. The main pathomechanism responsible for ACD is subclinical inflammation. The key element involved in iron metabolism is hepcidin, however, studies on new indices of iron status are in progress.The aim of the study was to assess the iron status in patients in early stages of chronic kidney disease, iron correlation with inflammation parameters and novel biomarkers of iron metabolism. Methods: The study included 69 patients. Standard laboratory measurements were used to measure the iron status, complete blood count, fibrinogen, prothrombin index, C-reactive protein concentration (CRP, creatinine, urea, uric acid. Commercially available kits were used to measure high-sensitivity CRP, interleukin 6 (IL-6, hepcidin-25, hemojuvelin, soluble transferrin receptor (sTfR, growth differentiation factor-15 (GDF-15 and zonulin. Results: Absolute iron deficiency was present in 17% of the patients, functional iron deficiency was present in 12% of the patients. Functional iron deficiency was associated with significantly higher serum levels of fibrinogen, ferritin, transferrin saturation, total iron binding capacity, hepcidin and older age relative to patients with absolute iron deficiency. In comparison with patients without iron deficiency, patients with functional iron deficiency were older, with lower prothrombin index, higher fibrinogen, CRP, hsCRP, sTfR, GDF-15, urea and lower eGFR. Hepcidin was predicted by markers of inflammation:ferritin, fibrinogen and IL-6. Conclusion: Inflammation is correlated with iron status. Novel biomarkers of iron metabolism might be useful to distinguish iron deficiency anemia connected with inflammation and absolute iron deficiency.

  20. Tuning the oxidative power of free iron-sulfur clusters.

    Science.gov (United States)

    Lang, Sandra M; Zhou, Shaodong; Schwarz, Helmut

    2017-03-15

    The gas-phase reactions between a series of di-iron sulfur clusters Fe 2 S x + (x = 1-3) and the small alkenes C 2 H 4 , C 3 H 6 , and C 4 H 8 have been investigated by means of Fourier-transform ion-cyclotron resonance mass spectrometry. For all studied alkenes, the reaction efficiency is found to increase in the order Fe 2 S + desulfurization of the cluster and formation of H 2 S. This indicates an increased propensity to induce oxidation reactions, i.e. oxidative power, of Fe 2 S 3 + that is attributed to an increased formal oxidation state of the iron atoms. Furthermore, the ability of Fe 2 S 3 + to activate and dissociate the C-H bonds of the alkenes is observed to increase with increasing size of the alkene and thus correlates with the alkene ionization energy.

  1. Which is the best oxidant for complexed iron removal from groundwater: The Kogalym case

    Energy Technology Data Exchange (ETDEWEB)

    Munter, R.; Overbeck, P.; Sutt, J. [Tallinn University of Technology, Tallinn (Estonia). Dept. of Chemical Engineering

    2008-07-01

    A short overview of the significance of a preoxidation stage groundwater treatment is presented. As an example the case of complexed iron removal from Kogalym groundwater (Tjumen, Siberia, Russian Federation) using different preoxidants (ozone, oxygen, chlorine, hydrogen peroxide, and potassium permanganate) is discussed. The key problem is stable di- and trivalent iron-organic complexes in groundwater which after aeration tend to pass through the hydroanthracite-sand gravity filters. The total organic carbon (TOC) content in raw groundwater is in the range of 3.2-6.4 mg/L, total iron content 2.7-6.0 mg/L and divalent iron content 2.4-4.0 mg/L. Separation from Kogalym groundwater by XAD-16 adsorbent humic matter fraction was homogeneous, with only 1 peak on the chromatogram with maximum Rt = 10.75 min and corresponding molecular mass 1911 ({lt} 2000). The final developed treatment technology is based on the water oxidation/reduction potential (ORP) optimization according to the iron system pE-pH diagram and consists of intensive aeration of raw water in the Gas-Degas Treatment (GDT) unit with the following sequence: filtration through the hydroanthracite and special anthracite Everzit, with intermediate enrichment of water with pure oxygen between the filtration stages.

  2. Interactions between iron oxides and copper oxides under hydrothermal conditions

    Energy Technology Data Exchange (ETDEWEB)

    McGarvey, G B; Owen, D G

    1995-08-01

    Under hydrothermal conditions, magnetite and hematite have been shown to undergo interconversion reactions, the extent of which is controlled in part by the presence of copper oxides. In oxygenated water, the degree to which magnetite was oxidized to hematite was found to be dependent on the presence of CuO or Cu{sub 2}O. When these materials were absent, the oxidation of magnetite was limited by the dissolved oxygen in the aqueous system. Participation of the copper oxides in the oxidation process was confirmed by more complete conversion of magnetite was also influenced by the presence of the copper oxides. In addition to driving the reduction to completion, the presence of the copper oxides also exerted a strong influence over the morphology of the magnetite that formed. (author). 13 refs., 1 tab., 3 figs.

  3. Oxide Dispersion Strengthened Iron Aluminide by CVD Coated Powders

    Energy Technology Data Exchange (ETDEWEB)

    Asit Biswas Andrew J. Sherman

    2006-09-25

    This I &I Category2 program developed chemical vapor deposition (CVD) of iron, aluminum and aluminum oxide coated iron powders and the availability of high temperature oxidation, corrosion and erosion resistant coating for future power generation equipment and can be used for retrofitting existing fossil-fired power plant equipment. This coating will provide enhanced life and performance of Coal-Fired Boilers components such as fire side corrosion on the outer diameter (OD) of the water wall and superheater tubing as well as on the inner diameter (ID) and OD of larger diameter headers. The program also developed a manufacturing route for readily available thermal spray powders for iron aluminide coating and fabrication of net shape component by powder metallurgy route using this CVD coated powders. This coating can also be applid on jet engine compressor blade and housing, industrial heat treating furnace fixtures, magnetic electronic parts, heating element, piping and tubing for fossil energy application and automotive application, chemical processing equipment , heat exchanger, and structural member of aircraft. The program also resulted in developing a new fabrication route of thermal spray coating and oxide dispersion strengthened (ODS) iron aluminide composites enabling more precise control over material microstructures.

  4. Films of double oxides of zirconium and iron

    International Nuclear Information System (INIS)

    Kozik, V.V.; Borilo, L.P.; Shul'pekov, A.M.

    2000-01-01

    Films of double oxides of zirconium and iron were prepared by the method of precipitation from film-forming alcohol solutions of zirconium oxychloride and iron chloride with subsequent thermal treatment. Using the methods of X-ray phase and differential thermal analyses, conductometry and optical spectroscopy, basic chemical processes occurring in the film-forming solutions and during thermal treatment are studied alongside with phase composition and optical characteristics of the films prepared. The composition-property diagrams of the given system in a thin-film state are plotted [ru

  5. Experimental investigation and thermodynamic simulation of the uranium oxide-zirconium oxide-iron oxide system in air

    Czech Academy of Sciences Publication Activity Database

    Petrov, Y. B.; Udalov, Y. P.; Šubrt, Jan; Bakardjieva, Snejana; Sázavský, P.; Kiselová, M.; Selucký, P.; Bezdička, Petr; Joumeau, C.; Piluso, P.

    2011-01-01

    Roč. 37, č. 2 (2011), s. 212-229 ISSN 1087-6596 Institutional research plan: CEZ:AV0Z40320502 Keywords : uranium oxide * zirconium oxide * iron oxide * fusibility curve * oxygen partial pressure * crystallization * phase composition Subject RIV: CA - Inorganic Chemistry Impact factor: 0.492, year: 2011

  6. Females Are Protected From Iron-Overload Cardiomyopathy Independent of Iron Metabolism: Key Role of Oxidative Stress.

    Science.gov (United States)

    Das, Subhash K; Patel, Vaibhav B; Basu, Ratnadeep; Wang, Wang; DesAulniers, Jessica; Kassiri, Zamaneh; Oudit, Gavin Y

    2017-01-23

    Sex-related differences in cardiac function and iron metabolism exist in humans and experimental animals. Male patients and preclinical animal models are more susceptible to cardiomyopathies and heart failure. However, whether similar differences are seen in iron-overload cardiomyopathy is poorly understood. Male and female wild-type and hemojuvelin-null mice were injected and fed with a high-iron diet, respectively, to develop secondary iron overload and genetic hemochromatosis. Female mice were completely protected from iron-overload cardiomyopathy, whereas iron overload resulted in marked diastolic dysfunction in male iron-overloaded mice based on echocardiographic and invasive pressure-volume analyses. Female mice demonstrated a marked suppression of iron-mediated oxidative stress and a lack of myocardial fibrosis despite an equivalent degree of myocardial iron deposition. Ovariectomized female mice with iron overload exhibited essential pathophysiological features of iron-overload cardiomyopathy showing distinct diastolic and systolic dysfunction, severe myocardial fibrosis, increased myocardial oxidative stress, and increased expression of cardiac disease markers. Ovariectomy prevented iron-induced upregulation of ferritin, decreased myocardial SERCA2a levels, and increased NCX1 levels. 17β-Estradiol therapy rescued the iron-overload cardiomyopathy in male wild-type mice. The responses in wild-type and hemojuvelin-null female mice were remarkably similar, highlighting a conserved mechanism of sex-dependent protection from iron-overload-mediated cardiac injury. Male and female mice respond differently to iron-overload-mediated effects on heart structure and function, and females are markedly protected from iron-overload cardiomyopathy. Ovariectomy in female mice exacerbated iron-induced myocardial injury and precipitated severe cardiac dysfunction during iron-overload conditions, whereas 17β-estradiol therapy was protective in male iron-overloaded mice.

  7. Study on electrolytic reduction with controlled oxygen flow for iron from molten oxide slag containing FeO

    Directory of Open Access Journals (Sweden)

    Gao Y.M.

    2013-01-01

    Full Text Available A ZrO2-based solid membrane electrolytic cell with controlled oxygen flow was constructed: graphite rod /[O]Fe+C saturated / ZrO2(MgO/(FeO slag/iron crucible. The feasibility of extraction of iron from molten oxide slag containing FeO at an applied voltage was investigated by means of the electrolytic cell. The effects of some important process factors on the FeO electrolytic reduction with the controlled oxygen flow were discussed. The results show that: solid iron can be extracted from molten oxide slag containing FeO at 1450ºC and an applied potential of 4V. These factors, such as precipitation and growth of solid iron dendrites, change of the cathode active area on the inner wall of the iron crucible and ion diffusion flux in the molten slag may affect the electrochemical reaction rate. The reduction for Fe2+ ions mainly appears on new iron dendrites of the iron crucible cathode, and a very small amount of iron are also formed on the MSZ (2.18% MgO partially stabilized zirconia tube/slag interface due to electronic conductance of MSZ tube. Internal electronic current through MSZ tube may change direction at earlier and later electrolytic reduction stage. It has a role of promoting electrolytic reduction for FeO in the molten slag at the earlier stage, but will lower the current efficiency at the later stage. The final reduction ratio of FeO in the molten slag can achieve 99%. A novel electrolytic method with controlled oxygen flow for iron from the molten oxide slag containing FeO was proposed. The theory of electrolytic reduction with the controlled oxygen flow was developed.

  8. Chronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks

    Science.gov (United States)

    Jones, J. Graham; Warner, C. G.

    1972-01-01

    Graham Jones, J., and Warner, C. G. (1972).Brit. J. industr. Med.,29, 169-177. Chronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks. Occupational and medical histories, smoking habits, respiratory symptoms, chest radiographs, and ventilatory capacities were studied in 14 steelworkers employed as deseamers of steel ingots for periods of up to 16 years. The men were exposed for approximately five hours of each working shift to fume concentrations ranging from 1·3 to 294·1 mg/m3 made up mainly of iron oxide with varying proportions of chromium oxide and nickel oxide. Four of the men, with 14 to 16 years' exposure, showed radiological evidence of pneumoconiosis classified as ILO categories 2 or 3. Of these, two had pulmonary function within the normal range and two had measurable loss of function, moderate in one case and mild in the other. Many observers would diagnose these cases as siderosis but the authors consider that this term should be reserved for cases exposed to pure iron compounds. The correct diagnosis is mixed-dust pneumoconiosis and the loss of pulmonary function is caused by the effects of the mixture of metallic oxides. It is probable that inhalation of pure iron oxide does not cause fibrotic pulmonary changes, whereas the inhalation of iron oxide plus certain other substances obviously does. Images PMID:5021996

  9. Altering the structure and properties of iron oxide nanoparticles and graphene oxide/iron oxide composites by urea

    Energy Technology Data Exchange (ETDEWEB)

    Naghdi, Samira [Physics department, Bu-Ali Sina University, 65174 Hamedan (Iran, Islamic Republic of); Department of Mechanical Engineering, College of Engineering, Kyung Hee University, 446-701 Yongin (Korea, Republic of); Rhee, Kyong Yop, E-mail: rheeky@khu.ac.kr [Department of Mechanical Engineering, College of Engineering, Kyung Hee University, 446-701 Yongin (Korea, Republic of); Jaleh, Babak [Physics department, Bu-Ali Sina University, 65174 Hamedan (Iran, Islamic Republic of); Park, Soo Jin [Chemistry, Colloge of Natural Science, Inha University, 402-751 Incheon (Korea, Republic of)

    2016-02-28

    Graphical abstract: - Highlights: • Iron oxide (Fe{sub 2}O{sub 3}) nanoparticles were directly grown on graphene oxide (GO) using a facile microwave assistant method. • The effect of urea concentration on Fe{sub 2}O{sub 3} nanoparticles and GO/Fe{sub 2}O{sub 3} composite was examined. • Increasing urea concentration altered the morphology and decreased the particle size. • The increased concentration of urea induced a larger surface area with more active sites in the Fe{sub 2}O{sub 3} nanoparticles. • The increase in urea concentration led to decreased thermal stability of the Fe{sub 2}O{sub 3} nanoparticles. - Abstract: Iron oxide (Fe{sub 2}O{sub 3}) nanoparticles were grown on graphene oxide (GO) using a simple microwave-assisted method. The effects of urea concentration on Fe{sub 2}O{sub 3} nanoparticles and GO/Fe{sub 2}O{sub 3} composite were examined. The as-prepared samples were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The Fe{sub 2}O{sub 3} nanoparticles were uniformly developed on GO sheets. The results showed that urea affects both Fe{sub 2}O{sub 3} morphology and particle size. In the absence of urea, the Fe{sub 2}O{sub 3} nanostructures exhibited a rod-like morphology. However, increasing urea concentration altered the morphology and decreased the particle size. The Raman results of GO/Fe{sub 2}O{sub 3} showed that the intensity ratio of D band to G band (I{sub D}/I{sub G}) was decreased by addition of urea, indicating that urea can preserve the GO sheets during synthesis of the composite from exposing more defects. The surface area and thermal stability of GO/Fe{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} were compared using the Brunauer–Emmett–Teller method and thermal gravimetric analysis, respectively. The results showed that the increased concentration of urea induced a larger surface area with more active sites in the Fe{sub 2}O{sub 3} nanoparticles. However, the increase in urea

  10. Interactions of silica with iron oxides: Effects on oxide transformations and sorption properties

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, P

    1995-08-01

    This report is a review of the literature on the adsorption of silica species on iron oxides and oxyhydroxides, and its effects on the adsorption of other species and on oxide interconversion reactions. The information is discussed briefly in the contexts of nuclear waste disposal and boiler-water chemistry. (author). 76 refs.

  11. Interactions of silica with iron oxides: Effects on oxide transformations and sorption properties

    International Nuclear Information System (INIS)

    Taylor, P.

    1995-08-01

    This report is a review of the literature on the adsorption of silica species on iron oxides and oxyhydroxides, and its effects on the adsorption of other species and on oxide interconversion reactions. The information is discussed briefly in the contexts of nuclear waste disposal and boiler-water chemistry. (author). 76 refs

  12. Oxidative stress response in neural stem cells exposed to different superparamagnetic iron oxide nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Pongrac, I. M.; Pavičić, I.; Milić, M.; Brkić Ahmed, L.; Babič, Michal; Horák, Daniel; Vinković Vrček, I.; Gajović, S.

    2016-01-01

    Roč. 11, 26 April (2016), s. 1701-1715 ISSN 1176-9114 R&D Projects: GA ČR(CZ) GC16-01128J EU Projects: European Commission(XE) 316120 - GLOWBRAIN Institutional support: RVO:61389013 Keywords : superparamagnetic iron oxide nanoparticles * biocompatibility * oxidative stress Subject RIV: CD - Macromolecular Chemistry

  13. Biogeochemistry of pyrite and iron sulfide oxidation in marine sediments

    DEFF Research Database (Denmark)

    Schippers, A.; Jørgensen, BB

    2002-01-01

    as substrates and NO3- as electron acceptor, in the presence of (FeS2)-Fe-55, to test for co-oxidation of FeS2, but an anaerobic microbial dissolution of (FeS2)-Fe-55, could not been detected. FeS2 and FeS were not oxidized by amorphous Fe(III) oxide in the presence of Fe-complexing organic compounds......Pyrite (FeS2) and iron monosulfide (FeS) play a central role in the sulfur and iron cycles of marine sediments, They may be buried in the sediment or oxidized by O-2 after transport by bioturbation to the sediment surface. FeS2 and FeS may also be oxidized within the anoxic sediment in which NO3...... marine sediments and incubated at different temperatures for > 1 yr. Bacteria could not be enriched with FeS2 as substrate or with FeS and amorphous Fe(III) oxide. With FeS and NO3-, 14 enrichments were obtained. One of these enrichments was further cultivated anaerobically with Fe2+ and S-0...

  14. Iron-mediated anaerobic oxidation of methane in brackish coastal sediments.

    Science.gov (United States)

    Egger, Matthias; Rasigraf, Olivia; Sapart, Célia J; Jilbert, Tom; Jetten, Mike S M; Röckmann, Thomas; van der Veen, Carina; Bândă, Narcisa; Kartal, Boran; Ettwig, Katharina F; Slomp, Caroline P

    2015-01-06

    Methane is a powerful greenhouse gas and its biological conversion in marine sediments, largely controlled by anaerobic oxidation of methane (AOM), is a crucial part of the global carbon cycle. However, little is known about the role of iron oxides as an oxidant for AOM. Here we provide the first field evidence for iron-dependent AOM in brackish coastal surface sediments and show that methane produced in Bothnian Sea sediments is oxidized in distinct zones of iron- and sulfate-dependent AOM. At our study site, anthropogenic eutrophication over recent decades has led to an upward migration of the sulfate/methane transition zone in the sediment. Abundant iron oxides and high dissolved ferrous iron indicate iron reduction in the methanogenic sediments below the newly established sulfate/methane transition. Laboratory incubation studies of these sediments strongly suggest that the in situ microbial community is capable of linking methane oxidation to iron oxide reduction. Eutrophication of coastal environments may therefore create geochemical conditions favorable for iron-mediated AOM and thus increase the relevance of iron-dependent methane oxidation in the future. Besides its role in mitigating methane emissions, iron-dependent AOM strongly impacts sedimentary iron cycling and related biogeochemical processes through the reduction of large quantities of iron oxides.

  15. Precipitation of iron (III) using magnesium oxide in fluidized bed

    International Nuclear Information System (INIS)

    Esteban-Bocardo, P. A.; Ferreira-Rocha, S. D.

    2006-01-01

    A process for iron (III) removal by hydroxide precipitation from and acid synthetic inorganic effluent using magnesium oxide as an alternative precipitant agent in a fluidized bed was developed. An acid synthetic inorganic effluent containing 100 and 200 mg/l of ferric ions (pH=1.0) was continuously fed up to the acrylic column (30 cm high and 2 cm diameter) during 180 minutes. Magnesium oxide pulp (3% v/v) was injected at the beginning of the experiment in order to allow the iron hydroxides precipitation. The concentration and pH profiles agreed in their curves, while the pH profile rose,the concentration profile decreased and a high percentage of iron removal /higher to 99%) was reached. Extremely low iron concentrations have been reached, thus permitting to attend to the environmental standard of 10.0 mg/l for discharge of effluent containing ferric ions established by the law DN 10/86 of COPAM (Conselho de Politica Ambiental do Estado de Minas Gerais-Brazil). (Author)

  16. Potential toxicity of superparamagnetic iron oxide nanoparticles (SPION

    Directory of Open Access Journals (Sweden)

    Neenu Singh

    2010-09-01

    Full Text Available Superparamagnetic iron oxide nanoparticles (SPION are being widely used for various biomedical applications, for example, magnetic resonance imaging, targeted delivery of drugs or genes, and in hyperthermia. Although, the potential benefits of SPION are considerable, there is a distinct need to identify any potential cellular damage associated with these nanoparticles. Besides focussing on cytotoxicity, the most commonly used determinant of toxicity as a result of exposure to SPION, this review also mentions the importance of studying the subtle cellular alterations in the form of DNA damage and oxidative stress. We review current studies and discuss how SPION, with or without different surface coating, may cause cellular perturbations including modulation of actin cytoskeleton, alteration in gene expression profiles, disturbance in iron homeostasis and altered cellular responses such as activation of signalling pathways and impairment of cell cycle regulation. The importance of protein–SPION interaction and various safety considerations relating to SPION exposure are also addressed.

  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. Promising iron oxide-based magnetic nanoparticles in biomedical engineering.

    Science.gov (United States)

    Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Vo, Toi Van; Lee, Beom-Jin

    2012-12-01

    For the past few decades biomedical engineering has imprinted its significant impact on the map of science through its wide applications on many other fields. An important example obviously proving this fact is the versatile application of magnetic nanoparticles in theranostics. Due to preferable properties such as biocompatibility, non-toxicity compared to other metal derivations, iron oxide-based magnetic nanoparticles was chosen to be addressed in this review. Aim of this review is to give the readers a whole working window of these magnetic nanoparticles in the current context of science. Thus, preparation of magnetic iron oxide nanoparticles with the so-far techniques, methods of characterizing the nanoparticles as well as their most recent biomedical applications will be stated.

  19. Photocatalytic Iron Oxide Micro-Swimmers for Environmental Remediation

    Science.gov (United States)

    Richard, Cynthia; Simmchen, Juliane; Eychmüller, Alexander

    2018-05-01

    Harvesting energy from photochemical reactions has long been studied as an efficient means of renewable energy, a topic that is increasingly gaining importance also for motion at the microscale. Iron oxide has been a material of interest in recent studies. Thus, in this work different synthesis methods and encapsulation techniques were used to try and optimize the photo-catalytic properties of iron oxide colloids. Photodegradation experiments were carried out following the encapsulation of the nanoparticles and the Fenton effect was also verified. The end goal would be to use the photochemical degradation of peroxide to propel an array of swimmers in a controlled manner while utilizing the Fenton effect for the degradation of dyes or waste in wastewater remediation.

  20. Synthesis, Characterization, and Cytotoxicity of Iron Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    S. Kanagesan

    2013-01-01

    Full Text Available In order to study the response of human breast cancer cells' exposure to nanoparticle, iron oxide (α-Fe2O3 nanoparticles were synthesized by a simple low temperature combustion method using Fe(NO33·9H2O as raw material. X-ray diffraction studies confirmed that the resultant powders are pure α-Fe2O3. Transmission electron microscopy study revealed the spherical shape of the primary particles, and the size of the iron oxide nanoparticles is in the range of 19 nm. The magnetic hysteresis loops demonstrated that the sample exposed ferromagnetic behaviors with a relatively low coercivity. The cytotoxicity of α-Fe2O3 nanoparticle was also evaluated on human breast cancer cells to address the current deficient knowledge of cellular response to nanoparticle exposure.

  1. Iron oxidation in different types of groundwater of Western Siberia

    Energy Technology Data Exchange (ETDEWEB)

    Serikov, Leonid V.; Tropina, Elena A.; Shiyan, Liudmila N. [Tomsk Polytechnic Univ., Tomsk (Russian Federation); Frimmel, Fritz H.; Metreveli, George; Delay, Markus [Univ. of Karlsruhe, Engler-Bunte-Inst. (Germany)

    2009-04-15

    Background, aim, and scope The groundwaters of Western Siberia contain high concentrations of iron, manganese, silicon, ammonium, and, in several cases, hydrogen sulfide, carbonic acids, and dissolved organic substances. Generally, the groundwaters of Western Siberia can be divided into two major types: one type with a relatively low concentration of humic substances and high hardness (water of A type) and a second type with a relatively low hardness and high concentration of humic substances (water of B type). For drinking water production, the waters of A type are mostly treated in the classical way by aeration followed by sand bed filtration. The waters of B type often show problems when treated for iron removal. A part of iron practically does not form the floes or particles suitable for filtration or sedimentation. The aim of this work was to determine the oxidizability of Fe(II), to characterize the iron colloids, and to investigate the complexation of the iron ions with humic substances and the coagulation of the iron colloids in the presence of dissolved organic matter. Materials and methods Water samples of the A and B types were taken from bore holes in Western Siberia (A type: in Tomsk and Tomsk region, B type: in Beliy Yar and Kargasok). Depth of sampling was about 200 m below surface. The oxidation of the groundwater samples by air oxygen and ozone was done in a bubble reactor consisting of a glass cylinder with a gas-inlet tube. To produce ozone, a compact ozone generator developed by Tomsk Polytechnic University was used. For the characterization of the colloids in the water of B type, the particle size distribution and the zeta potential were measured. To investigate the formation of complexes between iron and humic substances in the water of B type, size exclusion chromatography was used. The coagulation behavior of iron in the presence of dissolved organic substances was investigated at different pH values. The agglomerates were detected by

  2. Reduction Behaviors of Carbon Composite Iron Oxide Briquette Under Oxidation Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ki-Woo; Kim, Kang-Min; Kwon, Jae-Hong; Han, Jeong-Whan [Inha University, Incheon (Korea, Republic of); Son, Sang-Han [POSCO, Pohang (Korea, Republic of)

    2017-01-15

    The carbon composite iron oxide briquette (CCB) is considered a potential solution to the upcoming use of low grade iron resources in the ironmaking process. CCB is able to reduce raw material cost by enabling the use of low grade powdered iron ores and coal. Additionally, the fast reduction of iron oxides by direct contact with coal can be utilized. In this study, the reduction behaviors of CCB were investigated in the temperature range of 200-1200 ℃ under oxidizing atmosphere. Briquettes were prepared by mixing iron ore and coal in a weight ratio of 8:2. Then reduction experiments were carried out in a mixed gas atmosphere of N{sub 2}, O{sub 2}, and CO{sub 2}. Compressive strength tests and quantitative analysis were performed by taking samples at each target temperature. In addition, the reduction degree depending on the reaction time was evaluated by off-gas analysis during the reduction test. It was found that the compressive strength and the metallization degree of the reduced briquettes increased with increases in the reaction temperature and holding time. However, it tended to decrease when the re-oxidation phenomenon was caused by injected oxygen. The degree of reduction reached a maximum value in 26 minutes. Therefore, the re-oxidation phenomenon becomes dominant after 26 minutes.

  3. Linear-chain assemblies of iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dhak, Prasanta; Kim, Min-Kwan; Lee, Jae Hyeok; Kim, Miyoung; Kim, Sang-Koog, E-mail: sangkoog@snu.ac.kr

    2017-07-01

    Highlights: • Hydrothermal synthesis of pure phase 200 nm Fe{sub 3}O{sub 4} nanoparticles. • Studies of linear-chain assemblies of iron oxide nanosphere by FESEM. • Micromagnetic simulations showed the presence of 3D vortex states. • The B.E. for different numbers of particles in linear chain assemblies were calculated. - Abstract: We synthesized iron oxide nanoparticles using a simple hydrothermal approach and found several types of segments of their linear-chain self-assemblies as observed by field emission scanning electron microscopy. X-ray diffraction and transmission electron microscopy measurements confirm a well-defined single-phase FCC structure. Vibrating sample magnetometry measurements exhibit a ferromagnetic behavior. Micromagnetic numerical simulations show magnetic vortex states in the nanosphere model. Also, calculations of binding energies for different numbers of particles in the linear-chain assemblies explain a possible mechanism responsible for the self-assemblies of segments of the linear chains of nanoparticles. This work offers a step towards linear-chain self-assemblies of iron oxide nanoparticles and the effect of magnetic vortex states in individual nanoparticles on their binding energy.

  4. Gentamicin coated iron oxide nanoparticles as novel antibacterial agents

    Science.gov (United States)

    Bhattacharya, Proma; Neogi, Sudarsan

    2017-09-01

    Applications of different types of magnetic nanoparticles for biomedical purposes started a long time back. The concept of surface functionalization of the iron oxide nanoparticles with antibiotics is a novel technique which paves the path for further application of these nanoparticles by virtue of their property of superparamagnetism. In this paper, we have synthesized novel iron oxide nanoparticles surface functionalized with Gentamicin. The average size of the particles, concluded from the HR-TEM images, came to be around 14 nm and 10 nm for unmodified and modified nanoparticles, respectively. The magnetization curve M(H) obtained for these nanoparticles are typical of superparamagnetic nature and having almost zero values of coercivity and remanance. The release properties of the drug coated nanoparticles were studied; obtaining an S shaped profile, indicating the initial burst effect followed by gradual sustained release. In vitro investigations against various gram positive and gram negative strains viz Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis indicated significant antibacterial efficiency of the drug-nanoparticle conjugate. The MIC values indicated that a small amount like 0.2 mg ml-1 of drug capped particles induce about 98% bacterial death. The novelty of the work lies in the drug capping of the nanoparticles, which retains the superparamagnetic nature of the iron oxide nanoparticles and the medical properties of the drug simultaneously, which is found to extremely blood compatible.

  5. Optimization of Iron Oxide Tracer Synthesis for Magnetic Particle Imaging

    Directory of Open Access Journals (Sweden)

    Sabina Ziemian

    2018-03-01

    Full Text Available The optimization of iron oxide nanoparticles as tracers for magnetic particle imaging (MPI alongside the development of data acquisition equipment and image reconstruction techniques is crucial for the required improvements in image resolution and sensitivity of MPI scanners. We present a large-scale water-based synthesis of multicore superparamagnetic iron oxide nanoparticles stabilized with dextran (MC-SPIONs. We also demonstrate the preparation of single core superparamagnetic iron oxide nanoparticles in organic media, subsequently coated with a poly(ethylene glycol gallic acid polymer and phase transferred to water (SC-SPIONs. Our aim was to obtain long-term stable particles in aqueous media with high MPI performance. We found that the amplitude of the third harmonic measured by magnetic particle spectroscopy (MPS at 10 mT is 2.3- and 5.8-fold higher than Resovist for the MC-SPIONs and SC-SPIONs, respectively, revealing excellent MPI potential as compared to other reported MPI tracer particle preparations. We show that the reconstructed MPI images of phantoms using optimized multicore and specifically single-core particles are superior to that of commercially available Resovist, which we utilize as a reference standard, as predicted by MPS.

  6. Electron uptake by iron-oxidizing phototrophic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Bose, A; Gardel, EJ; Vidoudez, C; Parra, EA; Girguis, PR

    2014-02-26

    Oxidation-reduction reactions underlie energy generation in nearly all life forms. Although most organisms use soluble oxidants and reductants, some microbes can access solid-phase materials as electron-acceptors or -donors via extracellular electron transfer. Many studies have focused on the reduction of solid-phase oxidants. Far less is known about electron uptake via microbial extracellular electron transfer, and almost nothing is known about the associated mechanisms. Here we show that the iron-oxidizing photoautotroph Rhodopseudomonas palustris TIE-1 accepts electrons from a poised electrode, with carbon dioxide as the sole carbon source/electron acceptor. Both electron uptake and ruBisCo form I expression are stimulated by light. Electron uptake also occurs in the dark, uncoupled from photosynthesis. Notably, the pioABC operon, which encodes a protein system essential for photoautotrophic growth by ferrous iron oxidation, influences electron uptake. These data reveal a previously unknown metabolic versatility of photoferrotrophs to use extracellular electron transfer for electron uptake.

  7. Neutrophilic iron-oxidizing bacteria: occurrence and relevance in biological drinking water treatment

    DEFF Research Database (Denmark)

    Gülay, Arda; Musovic, Sanin; Albrechtsen, Hans-Jørgen

    2013-01-01

    Rapid sand filtration (RSF) is an economical way to treat anoxic groundwater around the world. It consists of groundwater aeration followed by passage through a sand filter. The oxidation and removal of ferrous iron, which is commonly found in anoxic groundwaters, is often believed to be a fully...... role of FeOB in iron removal at waterworks using RSF technologies....... physicochemical process. However, persistently low temperatures in RSF across Denmark may negatively affect the kinetics of chemical oxidation. The slower chemical oxidation of ferrous iron may increase the chances for iron bioconversion by neutrophilic iron-oxidizing bacteria (FeOB), which are found naturally...

  8. Iron Is the Active Site in Nickel/Iron Water Oxidation Electrocatalysts

    Directory of Open Access Journals (Sweden)

    Bryan M. Hunter

    2018-04-01

    Full Text Available Efficient catalysis of the oxygen-evolution half-reaction (OER is a pivotal requirement for the development of practical solar-driven water splitting devices. Heterogeneous OER electrocatalysts containing first-row transition metal oxides and hydroxides have attracted considerable recent interest, owing in part to the high abundance and low cost of starting materials. Among the best performing OER electrocatalysts are mixed Fe/Ni layered double hydroxides (LDH. A review of the available experimental data leads to the conclusion that iron is the active site for [NiFe]-LDH-catalyzed alkaline water oxidation.

  9. Regeneration of iron oxide containing pellets used for hot gas clean up

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, A.; Heeney, P.; Furimsky, E. (CANMET, Ottawa, Ontario (Canada). Energy Research Laboratories)

    1989-09-01

    Four iron-containing pelletized solids used for H{sub 2}S removal from hot gas were oxidized in a Cahn electrobalance and in a fixed bed reactor. The main reactions included the sequence in which FeS was oxidized to iron sulphate which then decomposed rapidly yielding SO{sub 2} and iron oxides. The oxidation occurred predominantly on the outer surface of the pellets. 12 refs., 5 figs., 5 tabs.

  10. Role of nitric oxide in cellular iron metabolism.

    Science.gov (United States)

    Kim, Sangwon; Ponka, Prem

    2003-03-01

    Iron regulatory proteins (IRP1 and IRP2) control the synthesis of transferrin receptors (TfR) and ferritin by binding to iron-responsive elements (IREs) which are located in the 3' untranslated region (UTR) and the 5' UTR of their respective mRNAs. Cellular iron levels affect binding of IRPs to IREs and consequently expression of TfR and ferritin. Moreover, NO*, a redox species of nitric oxide that interacts primarily with iron, can activate IRP1 RNA-binding activity resulting in an increase in TfR mRNA levels. We have shown that treatment of RAW 264.7 cells (a murine macrophage cell line) with NO+ (nitrosonium ion, which causes S-nitrosylation of thiol groups) resulted in a rapid decrease in RNA-binding of IRP2, followed by IRP2 degradation, and these changes were associated with a decrease in TfR mRNA levels. Moreover, we demonstrated that stimulation of RAW 264.7 cells with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) increased IRP1 binding activity, whereas RNA-binding of IRP2 decreased and was followed by a degradation of this protein. Furthermore, the decrease of IRP2 binding/protein levels was associated with a decrease in TfR mRNA levels in LPS/IFN-gamma-treated cells, and these changes were prevented by inhibitors of inducible nitric oxide synthase. These results suggest that NO+-mediated degradation of IRP2 plays a major role in iron metabolism during inflammation.

  11. Evaluation of tumoral enhancement by superparamagnetic iron oxide particles: comparative studies with ferumoxtran and anionic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Brillet, P-Y.; Gazeau, F.; Luciani, A.; Bessoud, B.; Cuenod, C.-A.; Siauve, N.; Pons, J.-N.; Poupon, J.; Clement, O.

    2005-01-01

    This study was designed to compare tumor enhancement by superparamagnetic iron oxide particles, using anionic iron oxide nanoparticles (AP) and ferumoxtran. In vitro, relaxometry and media with increasing complexity were used to assess the changes in r2 relaxivity due to cellular internalization. In vivo, 26 mice with subcutaneously implanted tumors were imaged for 24 h after injection of particles to describe kinetics of enhancement using T1 spin echo, T2 spin echo, and T2 fast spin echo sequences. In vitro, the r2 relaxivity decreased over time (0-4 h) when AP were uptaken by cells. The loss of r2 relaxivity was less pronounced with long (Hahn Echo) than short (Carr-Purcell-Meiboom-Gill) echo time sequences. In vivo, our results with ferumoxtran showed an early T2 peak (1 h), suggesting intravascular particles and a second peak in T1 (12 h), suggesting intrainterstitial accumulation of particles. With AP, the late peak (24 h) suggested an intracellular accumulation of particles. In vitro, anionic iron oxide nanoparticles are suitable for cellular labeling due to a high cellular uptake. Conversely, in vivo, ferumoxtran is suitable for passive targeting of tumors due to a favorable biodistribution. (orig.)

  12. Nitric oxide-mediated modulation of iron regulatory proteins: implication for cellular iron homeostasis.

    Science.gov (United States)

    Kim, Sangwon; Ponka, Prem

    2002-01-01

    Iron regulatory proteins (IRP1 and IRP2) control the synthesis of transferrin receptors (TfR) and ferritin by binding to iron-responsive elements (IREs) that are located in the 3' untranslated region (UTR) and the 5' UTR of their respective mRNAs. Cellular iron levels affect binding of IRPs to IREs and consequently expression of TfR and ferritin. Moreover, NO(.), a redox species of nitric oxide that interacts primarily with iron, can activate IRP1 RNA-binding activity resulting in an increase in TfR mRNA levels and a decrease in ferritin synthesis. We have shown that treatment of RAW 264.7 cells (a murine macrophage cell line) with NO(+) (nitrosonium ion, which causes S-nitrosylation of thiol groups) resulted in a rapid decrease in RNA-binding of IRP2, followed by IRP2 degradation, and these changes were associated with a decrease in TfR mRNA levels and a dramatic increase in ferritin synthesis. Moreover, we demonstrated that stimulation of RAW 264.7 cells with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) increased IRP1 binding activity, whereas RNA-binding of IRP2 decreased and was followed by a degradation of this protein. Furthermore, the decrease of IRP2 binding/protein levels was associated with a decrease in TfR mRNA levels and an increase in ferritin synthesis in LPS/IFN-gamma-treated cells, and these changes were prevented by inhibitors of inducible nitric oxide synthase. These results suggest that NO(+)-mediated degradation of IRP2 plays a major role in iron metabolism during inflammation.

  13. Oxidative diversification of amino acids and peptides by small-molecule iron catalysis.

    Science.gov (United States)

    Osberger, Thomas J; Rogness, Donald C; Kohrt, Jeffrey T; Stepan, Antonia F; White, M Christina

    2016-09-08

    Secondary metabolites synthesized by non-ribosomal peptide synthetases display diverse and complex topologies and possess a range of biological activities. Much of this diversity derives from a synthetic strategy that entails pre- and post-assembly oxidation of both the chiral amino acid building blocks and the assembled peptide scaffolds. The vancomycin biosynthetic pathway is an excellent example of the range of oxidative transformations that can be performed by the iron-containing enzymes involved in its biosynthesis. However, because of the challenges associated with using such oxidative enzymes to carry out chemical transformations in vitro, chemical syntheses guided by these principles have not been fully realized in the laboratory. Here we report that two small-molecule iron catalysts are capable of facilitating the targeted C-H oxidative modification of amino acids and peptides with preservation of α-centre chirality. Oxidation of proline to 5-hydroxyproline furnishes a versatile intermediate that can be transformed to rigid arylated derivatives or flexible linear carboxylic acids, alcohols, olefins and amines in both monomer and peptide settings. The value of this C-H oxidation strategy is demonstrated in its capacity for generating diversity: four 'chiral pool' amino acids are transformed to twenty-one chiral unnatural amino acids representing seven distinct functional group arrays; late-stage C-H functionalizations of a single proline-containing tripeptide furnish eight tripeptides, each having different unnatural amino acids. Additionally, a macrocyclic peptide containing a proline turn element is transformed via late-stage C-H oxidation to one containing a linear unnatural amino acid.

  14. Mercury removal in wastewater by iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Vélez, E; Campillo, G E; Morales, G; Hincapié, C; Osorio, J; Arnache, O; Uribe, J I; Jaramillo, F

    2016-01-01

    Mercury is one of the persistent pollutants in wastewater; it is becoming a severe environmental and public health problem, this is why nowadays its removal is an obligation. Iron oxide nanoparticles are receiving much attention due to their properties, such as: great biocompatibility, ease of separation, high relation of surface-area to volume, surface modifiability, reusability, excellent magnetic properties and relative low cost. In this experiment, Fe 3 O 4 and γ-Fe 2 O 3 nanoparticles were synthesized using iron salts and NaOH as precipitation agents, and Aloe Vera as stabilizing agent; then these nanoparticles were characterized by three different measurements: first, using a Zetasizer Nano ZS for their size estimation, secondly UV-visible spectroscopy which showed the existence of resonance of plasmon at λ max ∼360 nm, and lastly by Scanning Electron Microscopy (SEM) to determine nanoparticles form. The results of this characterization showed that the obtained Iron oxides nanoparticles have a narrow size distribution (∼100nm). Mercury removal of 70% approximately was confirmed by atomic absorption spectroscopy measurements. (paper)

  15. Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism

    Science.gov (United States)

    Price, Alex; Pearson, Victoria K.; Schwenzer, Susanne P.; Miot, Jennyfer; Olsson-Francis, Karen

    2018-01-01

    This work considers the hypothetical viability of microbial nitrate-dependent Fe2+ oxidation (NDFO) for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1–3.7 Ga) match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with appropriate

  16. Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism

    Directory of Open Access Journals (Sweden)

    Alex Price

    2018-03-01

    Full Text Available This work considers the hypothetical viability of microbial nitrate-dependent Fe2+ oxidation (NDFO for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1–3.7 Ga match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with

  17. Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism.

    Science.gov (United States)

    Price, Alex; Pearson, Victoria K; Schwenzer, Susanne P; Miot, Jennyfer; Olsson-Francis, Karen

    2018-01-01

    This work considers the hypothetical viability of microbial nitrate-dependent Fe 2+ oxidation (NDFO) for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe 2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe 2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1-3.7 Ga) match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe 2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with appropriate

  18. Factors affecting radium removal using mixed iron-manganese oxides

    International Nuclear Information System (INIS)

    Mott, H.V. Singh, S.; Kondapally, V.R.

    1993-01-01

    Batch experiments confirmed that sorption of radium by a mixed iron-manganese oxide solid phase shows promise for treating radium-contaminated water. The capacities of these mixed oxides for sorption of radium depend on the composition of the solid phase, the pH of the aqueous solution, and the presence of competing cations. The removal of the oxide-radium complexes from aqueous suspension by manganese greensand filtration was also investigated. It was found that influent radium concentrations of 100 pCi/L were reduced to 2--9 pCi/L by this process. Additional study of the fate of radium in manganese greensand filters is recommended before this procedure is used for drinking water treatment

  19. Factors affecting radium removal using mixed iron-manganese oxides

    Energy Technology Data Exchange (ETDEWEB)

    Mott, H.V. Singh, S.; Kondapally, V.R. (South Dakota School of Mines and Technology, Rapid City, SD (United States))

    1993-10-01

    Batch experiments confirmed that sorption of radium by a mixed iron-manganese oxide solid phase shows promise for treating radium-contaminated water. The capacities of these mixed oxides for sorption of radium depend on the composition of the solid phase, the pH of the aqueous solution, and the presence of competing cations. The removal of the oxide-radium complexes from aqueous suspension by manganese greensand filtration was also investigated. It was found that influent radium concentrations of 100 pCi/L were reduced to 2--9 pCi/L by this process. Additional study of the fate of radium in manganese greensand filters is recommended before this procedure is used for drinking water treatment.

  20. Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs

    Directory of Open Access Journals (Sweden)

    Jacob P. Beam

    2016-02-01

    Full Text Available Biomineralized ferric oxide microbial mats are ubiquitous features on Earth, are common in hot springs of Yellowstone National Park (YNP, WY, USA, and form due to direct interaction between microbial and physicochemical processes. The overall goal of this study was to determine the contribution of different community members to the assembly and succession of acidic high-temperature Fe(III-oxide mat ecosystems. Spatial and temporal changes in Fe(III-oxide accretion and the abundance of relevant community members were monitored over 70 days using sterile glass microscope slides incubated in the outflow channels of two acidic geothermal springs (pH = 3 - 3.5; temperature = 68 - 75 °C in YNP. Hydrogenobaculum spp. were the most abundant taxon identified during early successional stages (4 - 40 d, and have been shown to oxidize arsenite, sulfide, and hydrogen coupled to oxygen reduction. Iron-oxidizing populations of Metallosphaera yellowstonensis were detected within 4 d, and reached steady-state levels within 14 - 30 d, corresponding to visible Fe(III-oxide accretion. Heterotrophic archaea colonized near 30 d, and emerged as the dominant functional guild after 70 d and in mature Fe(III-oxide mats (1 - 2 cm thick. First-order rate constants of Fe(III-oxide accretion ranged from 0.046 - 0.05 d-1, and in situ microelectrode measurements showed that the oxidation of Fe(II is limited by the diffusion of O2 into the Fe(III-oxide mat. The formation of microterracettes also implicated O2 as a major variable controlling microbial growth and subsequent mat morphology. The assembly and succession of Fe(III-oxide mat communities follows a repeatable pattern of colonization by lithoautotrophic organisms, and the subsequent growth of diverse organoheterotrophs. The unique geochemical signatures and micromorphology of extant biomineralized Fe(III-oxide mats are useful for understanding other Fe(II-oxidizing systems.

  1. Iron/iron oxide core-shell nanoclusters for biomedical applications

    International Nuclear Information System (INIS)

    Qiang You; Antony, Jiji; Sharma, Amit; Nutting, Joseph; Sikes, Daniel; Meyer, Daniel

    2006-01-01

    Biocompatible magnetic nanoparticles have been found promising in several biomedical applications for tagging, imaging, sensing and separation in recent years. Most magnetic particles or beads currently used in biomedical applications are based on ferromagnetic iron oxides with very low specific magnetic moments of about 20-30 emu/g. Here we report a new approach to synthesize monodispersed core-shell nanostructured clusters with high specific magnetic moments above 200 emu/g. Iron nanoclusters with monodispersive size of diameters from 2 nm to 100 nm are produced by our newly developed nanocluster source and go to a deposition chamber, where a chemical reaction starts, and the nanoclusters are coated with iron oxides. HRTEM Images show the coatings are very uniform and stable. The core-shell nanoclusters are superparamagnetic at room temperature for sizes less than 15 nm, and then become ferromagnetic when the cluster size increases. The specific magnetic moment of core-shell nanoclusters is size dependent, and increases rapidly from about 80 emu/g at the cluster size of around 3 nm to over 200 emu/g up to the size of 100 nm. The use of high magnetic moment nanoclusters for biomedical applications could dramatically enhance the contrast for MRI, reduce the concentration of magnetic particle needs for cell separation, or make drug delivery possible with much lower magnetic field gradients

  2. Iron oxides, divalent cations, silica, and the early earth phosphorus crisis

    DEFF Research Database (Denmark)

    Jones, C.; Nomosatryo, S.; Crowe, S.A.

    2015-01-01

    As a nutrient required for growth, phosphorus regulates the activity of life in the oceans. Iron oxides sorb phosphorus from seawater, and through the Archean and early Proterozoic Eons, massive quantities of iron oxides precipitated from the oceans, producing a record of seawater chemistry...... that is preserved as banded iron formations (BIFs) today. Here we show that Ca2+, Mg2+, and silica in seawater control phosphorus sorption onto iron oxides, influencing the record of seawater phosphorus preserved in BIFs. Using a model for seawater cation chemistry through time, combined with the phosphorus...... waters shifted from phosphorus to iron limiting....

  3. Synthesis and Evaluation of Nanostructured Gold-Iron Oxide Catalysts for the Oxidative Dehydrogenation of Cyclohexane

    Science.gov (United States)

    Wu, Peng

    Shape-controlled iron oxide and gold-iron oxide catalysts with a cubic inverse spinel structure were studied in this thesis for the oxidative dehydrogenation of cyclohexane. The structure of iron oxide and gold-iron oxide catalysts has no major impact on their oxidative dehydrogenation activity. However, the product selectivity is influenced. Both cyclohexene and benzene are formed on bare iron oxide nanoshapes, while benzene is the only dehydrogenation product in the presence of gold. The selectivity of benzene over CO2 depends strongly on the stability of the iron oxide support and the gold-support interaction. The highest benzene yield has been observed on gold-iron oxide octahedra. {111}-bound nanooctahedra are highly stable in reaction conditions at 300 °C, while {100}-bound nanocubes start to sinter above 250 °C. The highest benzene yield has been observed on gold-iron oxide nanooctahedra, which are likely to have gold atoms, and few-atom gold clusters strongly-bound on their surface. Cationic gold appears to be the active site for benzene formation. An all-organic method to prepare Au-FeOx nano-catalysts is needed due to the inconvenience of the half-organic, half-inorganic synthesis process discussed above. Several methods from the literature to prepare gold-iron oxide nanocomposites completely in organic solvents were reviewed and followed. FeOx Au synthesis procedures in literatures are initially designed for a Au content of over 70%. This approach was tried here to prepare composites with a much lower Au content (2-5 atom. %). Heat treatment is required to bond Au and FeOx NPs in the organic-phase syntheses. Au-FeOx-4 was obtained as a selective catalyst for the ODH of cyclohexane. A Audelta+ peak is observed in the UV-Vis spectrum of sample Au-FeOx-4. This different Au delta+ form may be cationic Au nano-clusters interacting with the FeOx support. It has been demonstrated that cationic gold is responsible for dehydrogenation behavior. Furthermore, the

  4. RGD-conjugated iron oxide magnetic nanoparticles for magnetic resonance imaging contrast enhancement and hyperthermia.

    Science.gov (United States)

    Zheng, S W; Huang, M; Hong, R Y; Deng, S M; Cheng, L F; Gao, B; Badami, D

    2014-03-01

    The purpose of this study was to develop a specific targeting magnetic nanoparticle probe for magnetic resonance imaging and therapy in the form of local hyperthermia. Carboxymethyl dextran-coated ultrasmall superparamagnetic iron oxide nanoparticles with carboxyl groups were coupled to cyclic arginine-glycine-aspartic peptides for integrin α(v)β₃ targeting. The particle size, magnetic properties, heating effect, and stability of the arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide were measured. The arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide demonstrates excellent stability and fast magneto-temperature response. Magnetic resonance imaging signal intensity of Bcap37 cells incubated with arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide was significantly decreased compared with that incubated with plain ultrasmall superparamagnetic iron oxide. The preferential uptake of arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide by target cells was further confirmed by Prussian blue staining and confocal laser scanning microscopy.

  5. Hybrid dextran-iron oxide thin films deposited by laser techniques for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Predoi, D.; Ciobanu, C.S. [National Institute for Physics of Materials, P.O. Box MG 07, Bucharest, Magurele (Romania); Radu, M.; Costache, M.; Dinischiotu, A. [Molecular Biology Center, University of Bucharest, 91-95 Splaiul Independentei, 76201, Bucharest 5 (Romania); Popescu, C.; Axente, E.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiations Physics, P. O. Box MG 36, 77125 Bucharest (Romania); Gyorgy, E., E-mail: egyorgy@cin2.es [National Institute for Lasers, Plasma and Radiations Physics, P. O. Box MG 36, 77125 Bucharest (Romania); Consejo Superior de Investigaciones Cientificas, Centre d' Investigacions en Nanociencia i Nanotecnologia (CSIC-CIN2), Campus UAB, 08193 Bellaterra (Spain)

    2012-02-01

    Iron oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, non-irradiated iron oxide-dextran composite material. The biocompatibility of the iron oxide-dextran thin films was demonstrated by 3-(4.5 dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide-based colorimetric assay, using human liver hepatocellular carcinoma cells. - Highlights: Black-Right-Pointing-Pointer Hybrid, dextran-iron oxide nanoparticles and thin films. Black-Right-Pointing-Pointer Laser immobilization. Black-Right-Pointing-Pointer Biocompatibility of dextran-iron oxide nanoparticles.

  6. Hybrid dextran-iron oxide thin films deposited by laser techniques for biomedical applications

    International Nuclear Information System (INIS)

    Predoi, D.; Ciobanu, C.S.; Radu, M.; Costache, M.; Dinischiotu, A.; Popescu, C.; Axente, E.; Mihailescu, I.N.; Gyorgy, E.

    2012-01-01

    Iron oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, non-irradiated iron oxide-dextran composite material. The biocompatibility of the iron oxide-dextran thin films was demonstrated by 3-(4.5 dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide-based colorimetric assay, using human liver hepatocellular carcinoma cells. - Highlights: ► Hybrid, dextran-iron oxide nanoparticles and thin films. ► Laser immobilization. ► Biocompatibility of dextran-iron oxide nanoparticles.

  7. Liquid Phase Plasma Synthesis of Iron Oxide/Carbon Composite as Dielectric Material for Capacitor

    Directory of Open Access Journals (Sweden)

    Heon Lee

    2014-01-01

    Full Text Available Iron oxide/carbon composite was synthesized using a liquid phase plasma process to be used as the electrode of supercapacitor. Spherical iron oxide nanoparticles with the size of 5~10 nm were dispersed uniformly on carbon powder surface. The specific capacitance of the composite increased with increasing quantity of iron oxide precipitate on the carbon powder up to a certain quantity. When the quantity of the iron oxide precipitate exceeds the threshold, however, the specific capacitance was rather reduced by the addition of precipitate. The iron oxide/carbon composite containing an optimum quantity (0.33 atomic % of iron oxide precipitate exhibited the smallest resistance and the largest initial resistance slope.

  8. Conductive iron oxides accelerate thermophilic methanogenesis from acetate and propionate.

    Science.gov (United States)

    Yamada, Chihaya; Kato, Souichiro; Ueno, Yoshiyuki; Ishii, Masaharu; Igarashi, Yasuo

    2015-06-01

    Anaerobic digester is one of the attractive technologies for treatment of organic wastes and wastewater, while continuous development and improvements on their stable operation with efficient organic removal are required. Particles of conductive iron oxides (e.g., magnetite) are known to facilitate microbial interspecies electron transfer (termed as electric syntrophy). Electric syntrophy has been reported to enhance methanogenic degradation of organic acids by mesophilic communities in soil and anaerobic digester. Here we investigated the effects of supplementation of conductive iron oxides (magnetite) on thermophilic methanogenic microbial communities derived from a thermophilic anaerobic digester. Supplementation of magnetite accelerated methanogenesis from acetate and propionate under thermophilic conditions, while supplementation of ferrihydrite also accelerated methanogenesis from propionate. Microbial community analysis revealed that supplementation of magnetite drastically changed bacterial populations in the methanogenic acetate-degrading cultures, in which Tepidoanaerobacter sp. and Coprothermobacter sp. dominated. These results suggest that supplementation of magnetite induce electric syntrophy between organic acid-oxidizing bacteria and methanogenic archaea and accelerate methanogenesis even under thermophilic conditions. Findings from this study would provide a possibility for the achievement of stably operating thermophilic anaerobic digestion systems with high efficiency for removal of organics and generation of CH4. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  9. Iron oxide-based nanomagnets in nanomedicine: fabrication and applications

    Directory of Open Access Journals (Sweden)

    Meng Meng Lin

    2010-02-01

    Full Text Available Iron oxide-based nanomagnets have attracted a great deal of attention in nanomedicine over the past decade. Down to the nanoscale, superparamagnetic iron oxide nanoparticles can only be magnetized in the presence of an external magnetic field, which makes them capable of forming stable colloids in a physio-biological medium. Their superparamagnetic property, together with other intrinsic properties, such as low cytotoxicity, colloidal stability, and bioactive molecule conjugation capability, makes such nanomagnets ideal in both in-vitro and in-vivo biomedical applications. In this review, a chemical, physical, and biological synthetic approach to prepare iron oxide-based nanomagnets with different physicochemical properties was illustrated and compared. The growing interest in iron oxide-based nanomagnets with multifunctionalities was explored in cancer diagnostics and treatment, focusing on their combined roles in a magnetic resonance contrast agent, hyperthermia, and magnetic force assisted drug delivery. Iron oxides as magnetic carriers in gene therapy were reviewed with a focus on the sophisticated design and construction of magnetic vectors. Finally, the iron oxide-based nanomagnet also represents a very promising tool in particle/cell interfacing in controlling cellular functionalities, such as adhesion, proliferation, differentiation, and cell patterning, in stem cell therapy and tissue engineering applications. Meng Meng Lin received a BSc in biotechnology at the University of Hong Kong, China in 2004 and an MSc in biomedical nanotechnology at Newcastle University, UK, in 2005. She is currently working toward her PhD at the Institute of Science and Technology in Medicine, Keele University, UK. She was a visiting student at the Royal Institute of Technology, Sweden, in 2006. Her research interests include nanoparticles preparation, cell/nanomaterials interface, and cancer-oriented drug delivery. Hyung-Hwan Kim received an MSc degree in

  10. Thermally stimulated iron oxide transformations and magnetic behaviour of cerium dioxide/iron oxide reactive sorbents

    Czech Academy of Sciences Publication Activity Database

    Luňáček, J.; Životský, O.; Jirásková, Yvonna; Buršík, Jiří; Janoš, P.

    2016-01-01

    Roč. 120, OCT (2016), s. 295-303 ISSN 1044-5803 R&D Projects: GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : Oxide -nano-composites * Mössbauer spectroscopy * TEM * Cerium oxide * Magnetic parameters Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.714, year: 2016

  11. Aqueous dispersion of monodisperse magnetic iron oxide nanocrystals through phase transfer

    International Nuclear Information System (INIS)

    Yu, William W; Chang, Emmanuel; Sayes, Christie M; Drezek, Rebekah; Colvin, Vicki L

    2006-01-01

    A facile method was developed for completely transferring high quality monodisperse iron oxide nanocrystals from organic solvents to water. The as-prepared aqueous dispersions of iron oxide nanocrystals were extremely stable and could be functionalized for bioconjugation with biomolecules. These iron oxide nanocrystals showed negligible cytotoxicity to human breast cancer cells (SK-BR-3) and human dermal fibroblast cells. This method is general and versatile for many organic solvent-synthesized nanoparticles, including fluorescent semiconductor nanocrystals

  12. Sorption of trace amounts of gallium (III) on iron (III) oxide

    Energy Technology Data Exchange (ETDEWEB)

    Music, S; Gessner, M; Wolf, R H.H. [Institut Rudjer Boskovic, Zagreb (Yugoslavia)

    1979-01-01

    The sorption of trace amounts of gallium(III) on iron(III) oxide has been studied as a function of pH. Optimum conditions have been found for the preconcentration of traces of gallium(III) by iron(III) oxide. The influence of surface active substances and of complexing agents on the sorption of trace amounts of gallium(III) on iron(III) oxide has been also studied.

  13. Sorption of trace amounts of gallium (III) on iron (III) oxide

    International Nuclear Information System (INIS)

    Music, S.; Gessner, M.; Wolf, R.H.H.

    1979-01-01

    The sorption of trace amounts of gallium(III) on iron(III) oxide has been studied as a function of pH. Optimum conditions have been found for the preconcentration of traces of gallium(III) by iron(III) oxide. The influence of surface active substances and of complexing agents on the sorption of trace amounts of gallium(III) on iron(III) oxide has been also studied. (orig.) [de

  14. Changing of the electron structure of dispersed iron oxide during interaction with amines and borofluoride

    International Nuclear Information System (INIS)

    Hobert, H.; Arnold, D.

    1975-01-01

    The mechanism of chemisorption on the surface of iron oxide was studied by Moessbauer spectroscopy performed on samples of iron oxide finely dispersed in SiO 2 . It was found from Moessbauer spectra that the interaction of the oxide with amines resulted in a reversible electron transition from the amine to the adsorbent. The interaction with BF 3 brought about an irreversible electron transition from iron to boron. (A.K.)

  15. Iron modified titanium–hafnium binary oxides as catalysts in total oxidation of ethyl acetate

    Czech Academy of Sciences Publication Activity Database

    Tsoncheva, T.; Ivanova, R.; Henych, Jiří; Velinov, N.; Kormunda, M.; Dimitrov, M.; Paneva, D.; Slušná, Michaela; Mitov, I.; Štengl, Václav

    2016-01-01

    Roč. 81, JUN (2016), s. 14-19 ISSN 1566-7367 R&D Projects: GA MŠk LM2015073 Institutional support: RVO:61388980 Keywords : Titania–hafnia binary oxide s * Iron modifications * Support effect * Ethyl acetate oxydation Subject RIV: CA - Inorganic Chemistry Impact factor: 3.330, year: 2016

  16. Iron oxidation kinetics and phosphorus immobilization at the groundwater-surface water interface

    Science.gov (United States)

    van der Grift, Bas; Rozemeijer, Joachim; Griffioen, Jasper; van der Velde, Ype

    2014-05-01

    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 surface waters is controlled strongly by biogeochemical nutrient cycling processes at the soil-water interface. The mechanisms and rates of the iron oxidation process with associated binding of phosphate during exfiltration of anaerobic Fe(II) bearing groundwater are among the key unknowns in P retention processes in surface waters in delta areas where the shallow groundwater is typically pH-neutral to slightly acid, anoxic, iron-rich. We developed an experimental field set-up to study the dynamics in Fe(II) oxidation and mechanisms of P immobilization at the groundwater-surface water interface 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. The exfiltrating groundwater was captured in in-stream reservoirs constructed in the ditch. Through continuous discharge measurements and weekly water quality sampling of groundwater, tube drain water, exfiltrated groundwater, and ditch water, we quantified Fe(II) oxidation kinetics and P immobilization processes across the seasons. This study showed that seasonal changes in climatic conditions affect the Fe(II) oxidation process. In winter time the dissolved iron concentrations in the in-stream reservoirs reached the levels of the anaerobic groundwater. In summer time, the dissolved iron concentrations of the water in the reservoirs are low, indicating that dissolved Fe(II) is completely oxidized prior to inflow into the reservoirs. Higher discharges, lower temperatures and lower pH of the exfiltrated groundwater in winter compared to summer shifts the location of the redox transition zone

  17. Adsorption of Radioactive Chromium onto Iron Oxide Coated Sand

    International Nuclear Information System (INIS)

    Tadros, N.

    2008-01-01

    Iron oxide coated sand (IOCS) has been prepared and used as granular sorbent for 51 Cr radionuclide at different and specified concentration Ievels in aqueous solutions of constant ph value. Effect of different parameters such as: ph variation, contact time, 51 Cr ion concentration and variation of temperature on the adsorption of the radionuclide onto IOCS material have been discussed. At high ph value about 9()% of 51 Cr is adsorbed onto IOCS from the aqueous solution, The sorption capability of 51 Cr and the effect of ion concentration on the adsorbitivity have been discussed. Adsorption isotherms of Langmuir and Freundlich were expressed and their adsorption isotherm parameters are tabulated

  18. Iron oxide hydroxide nanoflower assisted removal of arsenic from water

    Energy Technology Data Exchange (ETDEWEB)

    Raul, Prasanta Kumar, E-mail: prasanta.drdo@gmail.com [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India); Devi, Rashmi Rekha; Umlong, Iohborlang M. [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India); Thakur, Ashim Jyoti [Department of Chemical Sciences, Tezpur University, Napaam, Tezpur 784028, Assam (India); Banerjee, Saumen; Veer, Vijay [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India)

    2014-01-01

    Graphical abstract: Non-magnetic polycrystalline iron oxide hydroxide nanoparticle with flower like morphology is found to play as an effective adsorbent media to remove As(III) from 300 μg L{sup −1} to less than 10 μg L{sup −1} from drinking water over wide range of pH. TEM image clearly reveals that the nanoparticle looks flower like morphology with average particle size less than 20 nm. The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic at room temperature and the data fitted to different isotherm models indicate the heterogeneity of the adsorbent surface. The material can be regenerated up to 70% using dilute hydrochloric acid and it would be utilized for de-arsenification purposes. - Highlights: • The work includes synthesis of iron oxide hydroxide nanoflower and its applicability for the removal of arsenic from water. • The nanoparticle was characterized using modern instrumental methods like FESEM, TEM, BET, XRD, etc. • The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic at room temperature. • The sorption is multilayered on the heterogeneous surface of the nano adsorbent. • The mechanism of arsenic removal of IOH nanoflower follows both adsorption and ion-exchange. - Abstract: Non-magnetic polycrystalline iron oxide hydroxide nanoparticle with flower like morphology is found to play as an effective adsorbent media to remove As(III) from 300 μg L{sup −1} to less than 10 μg L{sup −1} from drinking water over wide range of pH. The nanoparticle was characterized by X-ray powder diffraction analysis (XRD), BET surface area, FTIR, FESEM and TEM images. TEM image clearly reveals flower like morphology with average particle size less than 20 nm. The nanoflower morphology is also supported by FESEM images. The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic and the data fitted to different isotherm models indicate the

  19. Neutrophilic iron oxidizers adapted to highly oxic environments

    DEFF Research Database (Denmark)

    Gülay, Arda; Musovic, Sanin; Albrechtsen, Hans-Jørgen

    Rapid sand filtration is an economical way to treat anoxic groundwaters and involves aeration followed by particulate and soluble substrate removal via deep bed filtration. The anoxic source groundwater can contain several potential electron donors (CH4, Fe2+, Mn2+, NH4+ and assimilable organic...... of iron oxidizing bacterial in the highly oxic environments found in typical rapid sand filters. The neutrophilic FeOB were enriched by the Fe2+/O2 opposing gradient technique and quantified by MPN methodology. Diversity fingerprints of the enrichment cultures were obtained with a 16S rRNA targeted DGGE...

  20. Synthesis and Characterization of Holmium-Doped Iron Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Maarten Bloemen

    2014-02-01

    Full Text Available Rare earth atoms exhibit several interesting properties, for example, large magnetic moments and luminescence. Introducing these atoms into a different matrix can lead to a material that shows multiple interesting effects. Holmium atoms were incorporated into an iron oxide nanoparticle and the concentration of the dopant atom was changed in order to determine its influence on the host crystal. Its magnetic and magneto-optical properties were investigated by vibrating sample magnetometry and Faraday rotation measurements. The luminescent characteristics of the material, in solution and incorporated in a polymer thin film, were probed by fluorescence experiments.

  1. Contribution to the study of iron-manganese alloy oxidation in oxygen at high temperatures

    International Nuclear Information System (INIS)

    Olivier, Francoise

    1972-01-01

    This research thesis reports a systematic investigation of the oxidation of three relatively pure iron-manganese alloys in oxygen, under atmospheric pressure, and between 400 and 1000 C, these alloys being annealed as well as work-hardened. It also compares their behaviour with that of non-alloyed iron oxidized under the same conditions. The author describes the experimental techniques and installations, discusses the morphology of oxide films formed under the experimental conditions, discusses the film growth kinetics which is studied by thermogravimetry, proposes interpretations of results, and outlines the influence of manganese addition to iron on iron oxidation

  2. Radiation-induced synthesis of gold, iron-oxide composite nanoparticles

    International Nuclear Information System (INIS)

    Seino, Satoshi; Yamamoto, Takao; Nakagawa, Takashi; Kinoshita, Takuya; Kojima, Takao; Taniguchi, Ryoichi; Okuda, Shuichi

    2007-01-01

    Composite nanoparticles consisting of magnetic iron oxide nanoparticles and gold nanoparticles were synthesized using gamma-rays or electron beam. Ionizing irradiation induces the generation of reducing species inside the aqueous solution, and gold ions are reduced to form metallic Au nanoparticles. The size of Au nanoparticles depended on the dose rate and the concentration of support iron oxide. The gold nanoparticles on iron oxide nanoparticles selectively adsorb biomolecules via Au-S bonding. By using magnetic property of the support iron oxide nanoparticles, the composite nanoparticles are expected as a new type of magnetic nanocarrier for biomedical applications. (author)

  3. Synthesis of iron oxide nanoparticles via sonochemical method and their characterization

    Institute of Scientific and Technical Information of China (English)

    Amir Hassanjani-Roshan; Mohammad Reza Vaezi; Ali Shokuhfar; Zohreh Rajabali

    2011-01-01

    Preparation of iron oxide (α-Fe2O3) nanoparticles was carried out via a sonochemical process. The process parameters such as temperature,sonication time and power of ultrasonication play important roles in the size and morphology of the final products. The iron oxide nanoparticles were characterized by transmission electron microscopy,X-ray powder diffraction,and thermogravimetric and differential thermal analyses. From transmission electron microscopy observations,the size of the iron oxide nanoparticles is estimated to be significantly smaller than 19 nm. X-ray diffraction data of the powder after annealing provide direct evidence that the iron oxide was formed during the sonochemical process.

  4. Thermo-electric oxidization of iron in lithium niobate crystals

    International Nuclear Information System (INIS)

    Falk, Matthias

    2007-01-01

    Lithium niobate crystals (LiNbO 3 ) are a promising material for nonlinear-optical applications like frequency conversion to generate visible light, e.g., in laser displays, but their achievable output power is greatly limited by the ''optical damage'', i.e., light-induced refractive-index changes caused by excitation of electrons from iron impurities and the subsequent retrapping in unilluminated areas of the crystal. The resulting space-charge fields modify the refractive indices due to the electro-optic effect. By this ''photorefractive effect'' the phase-matching condition, i.e., the avoidance of destructive interference between light generated at different crystal positions due to the dispersion of the fundamental wave and the converted wave, is disturbed critically above a certain light intensity threshold. The influence of annealing treatments conducted in the presence of an externally applied electric field (''thermo-electric oxidization'') on the valence state of iron impurities and thereby on the optical damage is investigated. It is observed that for highly iron-doped LiNbO 3 crystals this treatment leads to a nearly complete oxidization from Fe 2+ to Fe 3+ indicated by the disappearance of the absorption caused by Fe 2+ . During the treatment an absorption front forms that moves through the crystal. The absorption in the visible as well as the electrical conductivity are decreased by up to five orders of magnitude due to this novel treatment. The ratio of the Fe 2+ concentration to the total iron concentration - a measure for the strength of the oxidization - is in the order of 10 -6 for oxidized crystals whereas it is about 10 -1 for untreated samples. Birefringence changes are observed at the absorption front that are explained by the removal of hydrogen and lithium ions from the crystal that compensate for the charges of the also removed electrons from Fe 2+ . A microscopic shock-wave model is developed that explains the observed absorption front by

  5. Neutrophilic Iron Oxidizing Bacteria: Occurrence and Relevance in Biological Drinking Water Treatment

    DEFF Research Database (Denmark)

    Gülay, Arda; Musovic, Sanin; Albrechtsen, Hans-Jørgen

    Rapid sand filtration (RSF) is an economical way to treat anoxic groundwater around the world. It consists of groundwater aeration followed by passage through a sand filter. The oxidation and removal of ferrous iron, which is commonly found in anoxic groundwaters, is often believed to be a fully......, neutrophilic iron oxidizers were present at the level of up to 7 105 cells per gram sediment. The spatial abundance and diversity of FeOB inferred by DGGE fingerprinting differed greatly both between and within individual sand filters. The results suggest a larger than assumed role of FeOB in iron removal...... physicochemical process. However, persistently low temperatures in RSF across Denmark may negatively affect the kinetics of chemical oxidation. The slower chemical oxidation of ferrous iron may increase the chances for iron bioconversion by neutrophilic iron-oxidizing bacteria (FeOB), which are found naturally...

  6. Macroscopic and microscopic biodistribution of intravenously administered iron oxide nanoparticles

    Science.gov (United States)

    Misra, Adwiteeya; Petryk, Alicia A.; Strawbridge, Rendall R.; Hoopes, P. Jack

    2015-03-01

    Iron oxide nanoparticles (IONP) are being developed for use as a cancer treatment. They have demonstrated efficacy when used either as a monotherapy or in conjunction with conventional chemotherapy and radiation. The success of IONP as a therapeutic tool depends on the delivery of a safe and controlled cytotoxic thermal dose to tumor tissue following activation with an alternating magnetic field (AMF). Prior to clinical approval, knowledge of IONP toxicity, biodistribution and physiological clearance is essential. This preliminary time-course study determines the acute toxicity and biodistribution of 110 nm dextran-coated IONP (iron) in mice, 7 days post systemic, at doses of 0.4, 0.6, and 1.0 mg Fe/ g mouse bodyweight. Acute toxicity, manifested as changes in the behavior of mice, was only observed temporarily at 1.0 mg Fe/ g mouse bodyweight, the highest dose administered. Regardless of dose, mass spectrometry and histological analysis demonstrated over 3 mg Fe/g tissue in organs within the reticuloendotheilial system (i.e. liver, spleen, and lymph nodes). Other organs (brain, heart, lungs, and kidney) had less than 0.5 mg Fe/g tissue with iron predominantly confined to the organ vasculature.

  7. MRI in acute cerebral ischaemia: perfusion imaging with superparamagnetic iron oxide in a rat model

    International Nuclear Information System (INIS)

    Forsting, M.; Reith, W.; Doerfler, A.; Kummer, R. von; Hacke, W.; Sartor, K.

    1994-01-01

    An imaging technique capable of detecting ischaemic cerebral injury at an early stage could improve diagnosis in acute or transient cerebral ischaemia. We compared the ability of superparamagnetically contrast-enhanced MRI and conventional T2-weighted MRI to detect ischaemic injury early after unilateral occlusion of the middle cerebral artery in 12 male Wistar rats. Permanent vessel occlusion was achieved by a transvascular approach, which has the advantage of not requiring a craniectom. At 45-60 min after the procedure, the animals had conventional T2-weighted MRI before and after administration of a superparamagnetic contrast agent (iron oxide particles). Unenhanced images were normal in all animals. After administration of iron oxide particles, the presumed ischaemic area was clearly visible, as relatively increased signal, in all animals; this high signal area corresponded to the area of ischaemic brain infarction seen on histological studies. Our results suggest that superparamagnetic iron particles may significantly reduce the interval between an ischaemic insult and the appearance of parenchymal changes on MRI. (orig./UWA)

  8. Molecular modeling studies of oleate adsorption on iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Rath, Swagat S. [CSIR-Institute of Minerals and Materials Technology, Bhubaneswar (India); Sinha, Nishant [Accelrys K.K, Bengaluru (India); Sahoo, Hrushikesh [CSIR-Institute of Minerals and Materials Technology, Bhubaneswar (India); Das, Bisweswar, E-mail: bdas@immt.res.in [CSIR-Institute of Minerals and Materials Technology, Bhubaneswar (India); Mishra, Barada Kanta [CSIR-Institute of Minerals and Materials Technology, Bhubaneswar (India)

    2014-03-01

    Graphical abstract: - Highlights: • Plane wave periodic DFT study of oleate-iron oxide interaction. • Magnetite-oleate complex is more stable than hematite and goethite. • Flotation recovery of magnetite is more compared to the other two oxides. - Abstract: Comparative studies of oleate interaction with hematite, magnetite and goethite using density functional calculations are presented. The approach is illustrated by carrying out geometric optimization of oleate on the stable and most exposed planes of hematite, magnetite, and goethite. Interaction energies for oleate-mineral surface have been determined, based on which, magnetite is found to be forming the most stable complex with oleate. Trend as obtained from the quantum chemical calculations has been validated by contact angle measurements and flotation studies on hematite, magnetite and goethite with sodium oleate at different pH and collector concentrations.

  9. Molecular modeling studies of oleate adsorption on iron oxides

    International Nuclear Information System (INIS)

    Rath, Swagat S.; Sinha, Nishant; Sahoo, Hrushikesh; Das, Bisweswar; Mishra, Barada Kanta

    2014-01-01

    Graphical abstract: - Highlights: • Plane wave periodic DFT study of oleate-iron oxide interaction. • Magnetite-oleate complex is more stable than hematite and goethite. • Flotation recovery of magnetite is more compared to the other two oxides. - Abstract: Comparative studies of oleate interaction with hematite, magnetite and goethite using density functional calculations are presented. The approach is illustrated by carrying out geometric optimization of oleate on the stable and most exposed planes of hematite, magnetite, and goethite. Interaction energies for oleate-mineral surface have been determined, based on which, magnetite is found to be forming the most stable complex with oleate. Trend as obtained from the quantum chemical calculations has been validated by contact angle measurements and flotation studies on hematite, magnetite and goethite with sodium oleate at different pH and collector concentrations

  10. Targeted magnetic iron oxide nanoparticles for tumor imaging and therapy

    Directory of Open Access Journals (Sweden)

    Xiang-Hong Peng

    2008-10-01

    Full Text Available Xiang-Hong Peng1,4, Ximei Qian2,4, Hui Mao3,4, Andrew Y Wang5, Zhuo (Georgia Chen1,4, Shuming Nie2,4, Dong M Shin1,4*1Department of Medical Oncology/Hematology; 2Department of Biomedical Engineering; 3Department of Radiology; 4Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA; 5Ocean Nanotech, LLC, Fayetteville, AR, USAAbstract: Magnetic iron oxide (IO nanoparticles with a long blood retention time, biodegradability and low toxicity have emerged as one of the primary nanomaterials for biomedical applications in vitro and in vivo. IO nanoparticles have a large surface area and can be engineered to provide a large number of functional groups for cross-linking to tumor-targeting ligands such as monoclonal antibodies, peptides, or small molecules for diagnostic imaging or delivery of therapeutic agents. IO nanoparticles possess unique paramagnetic properties, which generate significant susceptibility effects resulting in strong T2 and T*2 contrast, as well as T1 effects at very low concentrations for magnetic resonance imaging (MRI, which is widely used for clinical oncology imaging. We review recent advances in the development of targeted IO nanoparticles for tumor imaging and therapy.Keywords: iron oxide nanoparticles, tumor imaging, MRI, therapy

  11. Crystallization process and magnetic properties of amorphous iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Phu, N D; Luong, N H; Chau, N; Hai, N H; Ngo, D T; Hoang, L H

    2011-01-01

    This paper studied the crystallization process, phase transition and magnetic properties of amorphous iron oxide nanoparticles prepared by the microwave heating technique. Thermal analysis and magnetodynamics studies revealed many interesting aspects of the amorphous iron oxide nanoparticles. The as-prepared sample was amorphous. Crystallization of the maghemite γ-Fe 2 O 3 (with an activation energy of 0.71 eV) and the hematite α-Fe 2 O 3 (with an activation energy of 0.97 eV) phase occurred at around 300 deg. C and 350 deg. C, respectively. A transition from the maghemite to the hematite occurred at 500 deg. C with an activation energy of 1.32 eV. A study of the temperature dependence of magnetization supported the crystallization and the phase transformation. Raman shift at 660 cm -1 and absorption band in the infrared spectra at 690 cm -1 showed the presence of disorder in the hematite phase on the nanoscale which is supposed to be the origin of the ferromagnetic behaviour of that antiferromagnetic phase.

  12. Dechlorination of polychlorinated biphenyls by iron and its oxides.

    Science.gov (United States)

    Sun, Yifei; Liu, Xiaoyuan; Kainuma, Masashi; Wang, Wei; Takaoka, Masaki; Takeda, Nobuo

    2015-10-01

    The decomposition efficiency of polychlorinated biphenyls (PCBs) was determined using elemental iron (Fe) and three iron (hydr)oxides, i.e., α-Fe2O3, Fe3O4, and α-FeOOH, as catalysts. The experiments were performed using four distinct PCB congeners (PCB-209, PCB-153, and the coplanar PCB-167 and PCB-77) at temperatures ranging from 180 °C to 380 °C and under an inert, oxidizing or reducing atmosphere composed of N2, N2+O2, or N2+H2. From these three options N2 showed to provide the best reaction atmosphere. Among the iron compounds tested, Fe3O4 showed the highest activity for decomposing PCBs. The decomposition efficiencies of PCB-209, PCB-167, PCB-153, and PCB-77 by Fe3O4 in an N2 atmosphere at 230 °C were 88.5%, 82.5%, 69.9%, and 66.4%, respectively. Other inorganic chlorine (Cl) products which were measured by the amount of inorganic Cl ions represented 82.5% and 76.1% of the reaction products, showing that ring cleavage of PCBs was the main elimination process. Moreover, the dechlorination did not require a particular hydrogen donor. We used X-ray photoelectron spectroscopy to analyze the elemental distribution at the catalyst's surface. The O/Fe ratio influenced upon the decomposition efficiency of PCBs: the lower this ratio, the higher the decomposition efficiency. X-ray absorption near edge structure spectra showed that α-Fe2O3 effectively worked as a catalyst, while Fe3O4 and α-FeOOH were consumed as reactants, as their final state is different from their initial state. Finally, a decomposition pathway was postulated in which the Cl atoms in ortho-positions were more difficult to eliminate than those in the para- or meta-positions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Effect of the number of iron oxide nanoparticle layers on the magnetic properties of nanocomposite LbL assemblies

    International Nuclear Information System (INIS)

    Dincer, Ilker; Tozkoparan, Onur; German, Sergey V.; Markin, Alexey V.; Yildirim, Oguz; Khomutov, Gennady B.; Gorin, Dmitry A.; Venig, Sergey B.; Elerman, Yalcin

    2012-01-01

    Aqueous colloidal suspension of iron oxide nanoparticles has been synthesized. Z-potential of iron oxide nanoparticles stabilized by citric acid was −35±3 mV. Iron oxide nanoparticles have been characterized by the light scattering method and transmission electron microscopy. The polyelectrolyte/iron oxide nanoparticle thin films with different numbers of iron oxide nanoparticle layers have been prepared on the surface of silicon substrates via the layer-by-layer assembly technique. The physical properties and chemical composition of nanocomposite thin films have been studied by atomic force microscopy, magnetic force microscopy, magnetization measurements, Raman spectroscopy. Using the analysis of experimental data it was established, that the magnetic properties of nanocomposite films depended on the number of iron oxide nanoparticle layers, the size of iron oxide nanoparticle aggregates, the distance between aggregates, and the chemical composition of iron oxide nanoparticles embedded into the nanocomposite films. The magnetic permeability of nanocomposite coatings has been calculated. The magnetic permeability values depend on the number of iron oxide nanoparticle layers in nanocomposite film. - Highlights: ► The magnetic properties of nanocomposite films depended on the number of iron oxide nanoparticle layers. ► The iron oxide nanoparticle phase in nanocomposite coatings is a mixture of magnetite and maghemite phases. ► The magnetite and maghemite phases depend on a number of iron oxide nanoparticle layers because the iron oxide nanoparticles are oxidized from magnetite to maghemite.

  14. Photoreductive dissolution of iron oxides trapped in ice and its environmental implications.

    Science.gov (United States)

    Kim, Kitae; Choi, Wonyong; Hoffmann, Michael R; Yoon, Ho-Il; Park, Byong-Kwon

    2010-06-01

    The availability of iron has been thought to be a main limiting factor for the productivity of phytoplankton and related with the uptake of atmospheric CO(2) and algal blooms in fresh and sea waters. In this work, the formation of bioavailable iron (Fe(II)(aq)) from the dissolution of iron oxide particles was investigated in the ice phase under both UV and visible light irradiation. The photoreductive dissolution of iron oxides proceeded slowly in aqueous solution (pH 3.5) but was significantly accelerated in polycrystalline ice, subsequently releasing more bioavailable ferrous iron upon thawing. The enhanced photogeneration of Fe(II)(aq) in ice was confirmed regardless of the type of iron oxides [hematite, maghemite (gamma-Fe(2)O(3)), goethite (alpha-FeOOH)] and the kind of electron donors. The ice-enhanced dissolution of iron oxides was also observed under visible light irradiation, although the dissolution rate was much slower compared with the case of UV radiation. The iron oxide particles and organic electron donors (if any) in ice are concentrated and aggregated in the liquid-like grain boundary region (freeze concentration effect) where protons are also highly concentrated (lower pH). The enhanced photodissolution of iron oxides should occur in this confined boundary region. We hypothesized that electron hopping through the interconnected grain boundaries of iron oxide particles facilitates the separation of photoinduced charge pairs. The outdoor experiments carried out under ambient solar radiation of Ny-Alesund (Svalbard, 78 degrees 55'N) also showed that the generation of dissolved Fe(II)(aq) via photoreductive dissolution is enhanced when iron oxides are trapped in ice. Our results imply that the ice(snow)-covered surfaces and ice-cloud particles containing iron-rich mineral dusts in the polar and cold environments provide a source of bioavailable iron when they thaw.

  15. Photoactive thin film semiconducting iron pyrite prepared by sulfurization of iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Smestad, G.; Ennaoui, A.; Fiechter, S.; Tributsch, H.; Hofmann, W.K.; Birkholz, M. (Hahn-Meitner-Institut Berlin GmbH (Germany, F.R.). Abt. Solare Energetik Hahn-Meitner-Institut Berlin GmbH (Germany, F.R.). Abt. Materialforschung); Kautek, W. (Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany, F.R.))

    1990-03-01

    Photoactive iron pyrite (FeS{sub 2}) thin film layers have been synthesized by a simple method involving the reaction of Fe{sub 3}O{sub 4} or Fe{sub 2}O{sub 3} with elemental sulfur. The films were formed on a variety of different substrate materials by converting or sulfurizing iron oxide layers. The subsequent sulfur treatment of the oxide layers consisted of exposure of the films to gaseous sulfur in open or closed ampules at 350degC for 0.5-2 h. The morphology, composition and photoactivity of the films produced were checked using X-ray diffraction, X-ray photoelectron spectroscopy (ESCA), optical absorption, steady state and transient photoconductivity. The best films showed good crystallinity and purity with concurrent photoconductivity and photoelectrochemical response. The ability of this technique to produce photoactive material can be explained by interpretation of the Gibbs ternary phase diagram for the Fe-O-S system, and may be related to the production of photoactive pyrite in nature. A discussion is made as to the future improvement of the solar cell response by proper optimization of geometric and configurational properties. (orig.).

  16. Potential for microbial oxidation of ferrous iron in basaltic glass.

    Science.gov (United States)

    Xiong, Mai Yia; Shelobolina, Evgenya S; Roden, Eric E

    2015-05-01

    Basaltic glass (BG) is an amorphous ferrous iron [Fe(II)]-containing material present in basaltic rocks, which are abundant on rocky planets such as Earth and Mars. Previous research has suggested that Fe(II) in BG can serve as an energy source for chemolithotrophic microbial metabolism, which has important ramifications for potential past and present microbial life on Mars. However, to date there has been no direct demonstration of microbially catalyzed oxidation of Fe(II) in BG. In this study, three different culture systems were used to investigate the potential for microbial oxidation of Fe(II) in BG, including (1) the chemolithoautotrophic Fe(II)-oxidizing, nitrate-reducing "Straub culture"; (2) the mixotrophic Fe(II)-oxidizing, nitrate-reducing organism Desulfitobacterium frappieri strain G2; and (3) indigenous microorganisms from a streambed Fe seep in Wisconsin. The BG employed consisted of clay and silt-sized particles of freshly quenched lava from the TEB flow in Kilauea, Hawaii. Soluble Fe(II) or chemically reduced NAu-2 smectite (RS) were employed as positive controls to verify Fe(II) oxidation activity in the culture systems. All three systems demonstrated oxidation of soluble Fe(II) and/or structural Fe(II) in RS, whereas no oxidation of Fe(II) in BG material was observed. The inability of the Straub culture to oxidize Fe(II) in BG was particularly surprising, as this culture can oxidize other insoluble Fe(II)-bearing minerals such as biotite, magnetite, and siderite. Although the reason for the resistance of the BG toward enzymatic oxidation remains unknown, it seems possible that the absence of distinct crystal faces or edge sites in the amorphous glass renders the material resistant to such attack. These findings have implications with regard to the idea that Fe(II)-Si-rich phases in basalt rocks could provide a basis for chemolithotrophic microbial life on Mars, specifically in neutral-pH environments where acid-promoted mineral dissolution and

  17. Zonulin, inflammation and iron status in patients with early stages of chronic kidney disease

    OpenAIRE

    Lukaszyk, Ewelina; Lukaszyk, Mateusz; Koc-Zorawska, Ewa; Bodzenta-Lukaszyk, Anna; Malyszko, Jolanta

    2017-01-01

    Background/aims Zonulin is the only known regulator of intestinal permeability. It is also considered as a potential inflammatory marker in several conditions such as diabetes and inflammatory bowel syndrome. The aim of the study was to investigate zonulin levels in patients with early stages of CKD and its possible correlation with inflammation, anemia and iron status parameters. Methods Eighty-eight patients with early stages of CKD and 23 healthy volunteers were enrolled in the study. Zonu...

  18. Iron and manganese oxides modified maize straw to remove tylosin from aqueous solutions.

    Science.gov (United States)

    Yin, Yongyuan; Guo, Xuetao; Peng, Dan

    2018-08-01

    Maize straw modified by iron and manganese oxides was synthesized via a simple and environmentally friendly method. Three maize straw materials, the original maize straw, maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides, were detected by SEM, BET, XPS, XRD and FTIR. The results showed that maize straw was successfully modified and maize straw modified by iron and manganese oxides has a larger surface area than MS. According to the experimental data, the sorption trend could conform to the pseudo-second-order kinetic model well, and the sorption ability of tylosin on sorbents followed the order of original maize straw oxides iron and manganese oxides. The study indicated that manganese oxides and iron-manganese oxides could significantly enhance the sorption capacity of original maize straw. The sorption isotherm data of tylosin on original maize straw fit a linear model well, while Freundlich models were more suitable for maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides. The pH, ionic strength and temperature can affect the sorption process. The sorption mechanisms of tylosin on iron and manganese oxides modified maize straw were attribute to the surface complexes, electrostatic interactions, H bonding and hydrophobic interactions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Enhanced reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide

    International Nuclear Information System (INIS)

    Li, F.B.; Li, X.M.; Zhou, S.G.; Zhuang, L.; Cao, F.; Huang, D.Y.; Xu, W.; Liu, T.X.; Feng, C.H.

    2010-01-01

    The transformation of DDT was studied in an anaerobic system of dissimilatory iron-reducing bacteria (Shewanella decolorationis S12) and iron oxide (α-FeOOH). The results showed that S. decolorationis could reduce DDT into DDD, and DDT transformation rate was accelerated by the presence of α-FeOOH. DDD was observed as the primary transformation product, which was demonstrated to be transformed in the abiotic system of Fe 2+ + α-FeOOH and the system of DIRB + α-FeOOH. The intermediates of DDMS and DBP were detected after 9 months, likely suggesting that reductive dechlorination was the main dechlorination pathway of DDT in the iron-reducing system. The enhanced reductive dechlorination of DDT was mainly due to biogenic Fe(II) sorbed on the surface of α-FeOOH, which can serve as a mediator for the transformation of DDT. This study demonstrated the important role of DIRB and iron oxide on DDT and DDD transformation under anaerobic iron-reducing environments. - This is the first case reporting the reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide.

  20. Enhanced reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li, F.B., E-mail: cefbli@soil.gd.c [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Li, X.M. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Zhou, S.G.; Zhuang, L. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Cao, F. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Huang, D.Y.; Xu, W.; Liu, T.X. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Feng, C.H. [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China)

    2010-05-15

    The transformation of DDT was studied in an anaerobic system of dissimilatory iron-reducing bacteria (Shewanella decolorationis S12) and iron oxide (alpha-FeOOH). The results showed that S. decolorationis could reduce DDT into DDD, and DDT transformation rate was accelerated by the presence of alpha-FeOOH. DDD was observed as the primary transformation product, which was demonstrated to be transformed in the abiotic system of Fe{sup 2+} + alpha-FeOOH and the system of DIRB + alpha-FeOOH. The intermediates of DDMS and DBP were detected after 9 months, likely suggesting that reductive dechlorination was the main dechlorination pathway of DDT in the iron-reducing system. The enhanced reductive dechlorination of DDT was mainly due to biogenic Fe(II) sorbed on the surface of alpha-FeOOH, which can serve as a mediator for the transformation of DDT. This study demonstrated the important role of DIRB and iron oxide on DDT and DDD transformation under anaerobic iron-reducing environments. - This is the first case reporting the reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide.

  1. Nanoparticulate NaA zeolite composites for MRI: Effect of iron oxide content on image contrast

    Science.gov (United States)

    Gharehaghaji, Nahideh; Divband, Baharak; Zareei, Loghman

    2018-06-01

    In the current study, Fe3O4/NaA nanocomposites with various amounts of Fe3O4 (3.4, 6.8 & 10.2 wt%) were synthesized and characterized to study the effect of nano iron oxide content on the magnetic resonance (MR) image contrast. The cell viability of the nanocomposites was investigated by MTT assay method. T2 values as well as r2 relaxivities were determined with a 1.5 T MRI scanner. The results of the MTT assay confirmed the nanocomposites cytocompatibility up to 6.8% of the iron oxide content. Although the magnetization saturations and susceptibility values of the nanocomposites were increased as a function of the iron oxide content, their relaxivity was decreased from 921.78 mM-1 s-1 for the nanocomposite with the lowest iron oxide content to 380.16 mM-1 s-1 for the highest one. Therefore, Fe3O4/NaA nanocomposite with 3.4% iron oxide content led to the best MR image contrast. Nano iron oxide content and dispersion in the nanocomposites structure have important role in the nanocomposite r2 relaxivity and the MR image contrast. Aggregation of the iron oxide nanoparticles is a limiting factor in using of the high iron oxide content nanocomposites.

  2. Synthesis and applications of nano-structured iron oxides/hydroxides

    African Journals Online (AJOL)

    ... in numerous synthesis processes. This review outlines the work being carried out on synthesis of iron oxides in nano form and their various applications. Keywords: nano iron oxides, synthesis, catalysts, magnetic properties, biomedical application. International Journal of Engineering, Science and Technology, Vol. 2, No.

  3. Iron induced RNA-oxidation in the general population and in mouse tissue

    DEFF Research Database (Denmark)

    Cejvanovic, Vanja; Kjær, Laura Kofoed; Bergholdt, Helle Kirstine Mørup

    2018-01-01

    Iron promotes formation of hydroxyl radicals by the Fenton reaction, subsequently leading to potential oxidatively generated damage of nucleic acids. Oxidatively generated damage to RNA, measured as 8-oxo-7,8-dihydroguanosine (8-oxoGuo) in urine, is increased in patients with genetic iron overloa...

  4. Biological iron(II) oxidation as pre-treatment to limestone neutralisation of acid water

    CSIR Research Space (South Africa)

    Maree

    1998-01-01

    Full Text Available at investigating the effect of surface area of the medium that supports bacterial growth on the rate of biological iron (II) oxidation. The study showed that the biological iron (II) oxidation rate is directly proportional to the square root of the medium specific...

  5. HREM investigation of the constitution and the crystallography of thin thermal oxide layers on iron

    DEFF Research Database (Denmark)

    Graat, P.C.J.; Brongers, M.P.H.; Zandbergen, H.W.

    1997-01-01

    Oxide layers formed at 573 K in O2 at atmospheric pressure, both on a clean iron surface and on an iron surface covered with an etching induced (hydro)oxide film, were investigated with high-resolution transmission electron microscopy (HREM). Cross-sections of oxidised samples were prepared by a ...

  6. Spin-lock MR enhances the detection sensitivity of superparamagnetic iron oxide particles

    NARCIS (Netherlands)

    Moonen, R.P.M.; van der Tol, P.; Hectors, S.J.C.G.; Starmans, L.W.E.; Nicolaij, K.; Strijkers, G.J.

    2015-01-01

    Purpose To evaluate spin-lock MR for detecting superparamagnetic iron oxides and compare the detection sensitivity of quantitative T1ρ with T2 imaging. Methods In vitro experiments were performed to investigate the influence of iron oxide particle size and composition on T1ρ. These comprise T1ρ and

  7. Spin-lock MR enhances the detection sensitivity of superparamagnetic iron oxide particles

    NARCIS (Netherlands)

    Moonen, Rik P. M.; van der Tol, Pieternel; Hectors, Stefanie J. C. G.; Starmans, Lucas W. E.; Nicolay, Klaas; Strijkers, Gustav J.

    2015-01-01

    To evaluate spin-lock MR for detecting superparamagnetic iron oxides and compare the detection sensitivity of quantitative T1ρ with T2 imaging. In vitro experiments were performed to investigate the influence of iron oxide particle size and composition on T1ρ . These comprise T1ρ and T2 measurements

  8. Iron oxide/cassava starch-supported Ziegler-Natta catalysts for in situ ethylene polymerization.

    Science.gov (United States)

    Chancharoenrith, Sittikorn; Kamonsatikul, Choavarit; Namkajorn, Montree; Kiatisevi, Supavadee; Somsook, Ekasith

    2015-03-06

    Iron oxide nanoparticles were used as supporters for in situ polymerization to produce polymer nanocomposites with well-dispersed fillers in polymer matrix. Iron oxide could be sustained as colloidal solutions by cassava starch to produce a good dispersion of iron oxide in the matrix. New supports based on iron oxide/cassava starch or cassava starch for Ziegler-Natta catalysts were utilized as heterogeneous supporters for partially hydrolyzed triethylaluminum. Then, TiCl4 was immobilized on the supports as catalysts for polymerization of ethylene. High-density polyethylene (HDPE) composites were obtained by the synthesized catalysts. A good dispersion of iron oxide/cassava starch particles was observed in the synthesized polymer matrix promoting to good mechanical properties of HDPE. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. The early stages of oxidation of magnesium single crystal surfaces

    International Nuclear Information System (INIS)

    Hayden, B.E.; Schweizer, E.; Koetz, R.; Bradshaw, A.M.

    1981-01-01

    The early stages of oxidation of Mg(001) and Mg(100) single crystal surfaces at 300 K have been investigated by LEED, ELS, work function and ellipsometric measurements. A sharp decrease in work function on both surfaces during the first 12 L exposure indicates the incorporation of oxygen in the earliest stages of the interaction. The incorporated oxygen on Mg(001) gives rise to a broadening of the integral order LEED spots for an exposure 3 L. (orig.)

  10. Synthesis, characterization and mechanistic insights of mycogenic iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bhargava, Arpit; Jain, Navin; Manju Barathi L [Birla Institute of Technology and Science, Centre for Biotechnology, Department of Biological Sciences (India); Akhtar, Mohd Sayeed [Jimma University, Department of Applied Microbiology, College of Natural Sciences (Ethiopia); Yun, Yeoung-Sang [Chonbuk National University, Division of Environmental and Chemical Engineering (Korea, Republic of); Panwar, Jitendra, E-mail: drjitendrapanwar@yahoo.co.in [Birla Institute of Technology and Science, Centre for Biotechnology, Department of Biological Sciences (India)

    2013-11-15

    In the present study, extracellular synthesis of iron oxide nanoparticles (IONPs) was achieved using Aspergillus japonicus isolate AJP01. The isolate demonstrated its ability to hydrolyze the precursor salt solution, a mixture of iron cyanide complexes, under ambient conditions. Hydrolysis of these complexes released ferric and ferrous ions, which underwent protein-mediated coprecipitation and controlled nucleation resulting in the formation of IONPs. Transmission electron microscopy, selected area electron diffraction pattern, energy dispersive spectroscopy and grazing incidence X-ray diffraction analysis confirmed the mycosynthesis of IONPs. The synthesized particles were cubic in shape with a size range of 60–70 nm with crystal structure corresponding to magnetite. Scanning electron microscopy analysis revealed the absence of IONPs on fungal biomass surface, indicating the extracellular nature of synthesis. Fourier transform infrared spectroscopy confirmed the presence of proteins on as-synthesised IONPs, which may confer their stability. Preliminary investigation indicated the role of proteins in the synthesis and stabilization of IONPs. On the basis of present findings, a probable mechanism for synthesis of IONPs is suggested. The simplicity and versatility of the present approach can be utilized for the synthesis of other nanomaterials.

  11. Effect of particle size on iron nanoparticle oxidation state

    International Nuclear Information System (INIS)

    Lombardo, Jeffrey J.; Lysaght, Andrew C.; Goberman, Daniel G.; Chiu, Wilson K.S.

    2012-01-01

    Selecting catalyst particles is a very important part of carbon nanotube growth, although the properties of these nanoscale particles are unclear. In this article iron nanoparticles are analyzed through the use of atomic force microscopy and x-ray photoelectron spectroscopy in order to understand how the size affects the chemical composition of nanoparticles and thus their physical structure. Initially, atomic force microscopy was used to confirm the presence of iron particles, and to determine the average size of the particles. Next an analytical model was developed to estimate particle size as a function of deposition time using inputs from atomic force microscopy measurement. X-ray photoelectron spectroscopy analysis was then performed with a focus on the spectra relating to the 2p Fe electrons to study the chemical state of the particles as a function of time. It was shown that as the size of nanoparticles decreased, the oxidation state of the particles changed due to a high proportion of atoms on the surface.

  12. Efficient Low-pH Iron Removal by a Microbial Iron Oxide Mound Ecosystem at Scalp Level Run.

    Science.gov (United States)

    Grettenberger, Christen L; Pearce, Alexandra R; Bibby, Kyle J; Jones, Daniel S; Burgos, William D; Macalady, Jennifer L

    2017-04-01

    Acid mine drainage (AMD) is a major environmental problem affecting tens of thousands of kilometers of waterways worldwide. Passive bioremediation of AMD relies on microbial communities to oxidize and remove iron from the system; however, iron oxidation rates in AMD environments are highly variable among sites. At Scalp Level Run (Cambria County, PA), first-order iron oxidation rates are 10 times greater than at other coal-associated iron mounds in the Appalachians. We examined the bacterial community at Scalp Level Run to determine whether a unique community is responsible for the rapid iron oxidation rate. Despite strong geochemical gradients, including a >10-fold change in the concentration of ferrous iron from 57.3 mg/liter at the emergence to 2.5 mg/liter at the base of the coal tailings pile, the bacterial community composition was nearly constant with distance from the spring outflow. Scalp Level Run contains many of the same taxa present in other AMD sites, but the community is dominated by two strains of Ferrovum myxofaciens , a species that is associated with high rates of Fe(II) oxidation in laboratory studies. IMPORTANCE Acid mine drainage pollutes more than 19,300 km of rivers and streams and 72,000 ha of lakes worldwide. Remediation is frequently ineffective and costly, upwards of $100 billion globally and nearly $5 billion in Pennsylvania alone. Microbial Fe(II) oxidation is more efficient than abiotic Fe(II) oxidation at low pH (P. C. Singer and W. Stumm, Science 167:1121-1123, 1970, https://doi.org/10.1126/science.167.3921.1121). Therefore, AMD bioremediation could harness microbial Fe(II) oxidation to fuel more-cost-effective treatments. Advances will require a deeper understanding of the ecology of Fe(II)-oxidizing microbial communities and the factors that control their distribution and rates of Fe(II) oxidation. We investigated bacterial communities that inhabit an AMD site with rapid Fe(II) oxidation and found that they were dominated by two

  13. In-situ synthesis of magnetic iron-oxide nanoparticle-nanofibre composites using electrospinning

    International Nuclear Information System (INIS)

    Burke, Luke; Mortimer, Chris J.; Curtis, Daniel J.; Lewis, Aled R.; Williams, Rhodri; Hawkins, Karl; Maffeis, Thierry G.G.; Wright, Chris J.

    2017-01-01

    We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125 ± 18 nm (PEO) and 1.58 ± 0.28 μm (PVP); Free-surface electrospun: 155 ± 31 nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8 ± 3 nm to 27 ± 5 nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique. - Graphical abstract: We present a novel facile, one-step process for the in-situ synthesis of magnetic iron oxide nanoparticle-nanofibre composites using both needle and free-surface electrospinning. This is a significant step forward for production rates of magnetic nanoparticle-nanofibre scaffolds both in terms of fibre and nanoparticle production. - Highlights: • We present a novel process for the in-situ synthesis of magnetic iron oxide nanoparticle

  14. In-situ synthesis of magnetic iron-oxide nanoparticle-nanofibre composites using electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Luke; Mortimer, Chris J. [Biomaterials, Biofouling and Biofilms Engineering Laboratory (B3EL), Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Curtis, Daniel J.; Lewis, Aled R.; Williams, Rhodri [Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Hawkins, Karl [Centre for NanoHealth (CNH), Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Maffeis, Thierry G.G. [Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Wright, Chris J., E-mail: c.wright@swansea.ac.uk [Biomaterials, Biofouling and Biofilms Engineering Laboratory (B3EL), Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Centre for NanoHealth (CNH), Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom)

    2017-01-01

    We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125 ± 18 nm (PEO) and 1.58 ± 0.28 μm (PVP); Free-surface electrospun: 155 ± 31 nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8 ± 3 nm to 27 ± 5 nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique. - Graphical abstract: We present a novel facile, one-step process for the in-situ synthesis of magnetic iron oxide nanoparticle-nanofibre composites using both needle and free-surface electrospinning. This is a significant step forward for production rates of magnetic nanoparticle-nanofibre scaffolds both in terms of fibre and nanoparticle production. - Highlights: • We present a novel process for the in-situ synthesis of magnetic iron oxide nanoparticle

  15. Bioconjugated iron oxide nanocubes: synthesis, functionalization, and vectorization.

    Science.gov (United States)

    Wortmann, Laura; Ilyas, Shaista; Niznansky, Daniel; Valldor, Martin; Arroub, Karim; Berger, Nadja; Rahme, Kamil; Holmes, Justin; Mathur, Sanjay

    2014-10-08

    A facile bottom-up approach for the synthesis of inorganic/organic bioconjugated nanoprobes based on iron oxide nanocubes as the core with a nanometric silica shell is demonstrated. Surface coating and functionalization protocols developed in this work offered good control over the shell thickness (8-40 nm) and enabled biovectorization of SiO2@Fe3O4 core-shell structures by covalent attachment of folic acid (FA) as a targeting unit for cellular uptake. The successful immobilization of folic acid was investigated both quantitatively (TGA, EA, XPS) and qualitatively (AT-IR, UV-vis, ζ-potential). Additionally, the magnetic behavior of the nanocomposites was monitored after each functionalization step. Cell viability studies confirmed low cytotoxicity of FA@SiO2@Fe3O4 conjugates, which makes them promising nanoprobes for targeted internalization by cells and their imaging.

  16. Magnetic Iron Oxide Nanowires Formed by Reactive Dewetting.

    Science.gov (United States)

    Bennett, Roger A; Etman, Haitham A; Hicks, Hannah; Richards, Leah; Wu, Chen; Castell, Martin R; Dhesi, Sarnjeet S; Maccherozzi, Francesco

    2018-04-11

    The growth and reactive dewetting of ultrathin films of iron oxides supported on Re(0001) surfaces have been imaged in situ in real time. Initial growth forms a nonmagnetic stable FeO (wüstite like) layer in a commensurate network upon which high aspect ratio nanowires of several microns in length but less than 40 nm in width can be fabricated. The nanowires are closely aligned with the substrate crystallography and imaging by X-ray magnetic circular dichroism shows that each contain a single magnetic domain. The driving force for dewetting appears to be the minimization of strain energy of the Fe 3 O 4 crystallites and follows the Tersoff and Tromp model in which strain is minimized at constant height by extending in one epitaxially matched direction. Such wires are promising in spintronic applications and we predict that the growth will also occur on other hexagonal substrates.

  17. Genotoxicity of Superparamagnetic Iron Oxide Nanoparticles in Granulosa Cells

    Directory of Open Access Journals (Sweden)

    Marina Pöttler

    2015-11-01

    Full Text Available Nanoparticles that are aimed at targeting cancer cells, but sparing healthy tissue provide an attractive platform of implementation for hyperthermia or as carriers of chemotherapeutics. According to the literature, diverse effects of nanoparticles relating to mammalian reproductive tissue are described. To address the impact of nanoparticles on cyto- and genotoxicity concerning the reproductive system, we examined the effect of superparamagnetic iron oxide nanoparticles (SPIONs on granulosa cells, which are very important for ovarian function and female fertility. Human granulosa cells (HLG-5 were treated with SPIONs, either coated with lauric acid (SEONLA only, or additionally with a protein corona of bovine serum albumin (BSA; SEONLA-BSA, or with dextran (SEONDEX. Both micronuclei testing and the detection of γH2A.X revealed no genotoxic effects of SEONLA-BSA, SEONDEX or SEONLA. Thus, it was demonstrated that different coatings of SPIONs improve biocompatibility, especially in terms of genotoxicity towards cells of the reproductive system.

  18. Iron oxide nanoparticle hyperthermia and chemotherapy cancer treatment

    Science.gov (United States)

    Petryk, A. A.; Giustini, A. J.; Ryan, P.; Strawbridge, R. R.; Hoopes, P. J.

    2009-02-01

    The benefit of combining hyperthermia and chemotherapy to treat cancer is well established. However, combined therapy has not yet achieved standard of care status. The reasons are numerous and varied, however the lack of significantly greater tumor cell sensitivity to heat (as compared to normal cells) and the inability to deliver heat to the tumor in a precise manner have been major factors. Iron oxide nanoparticle (IONP) hyperthermia, alone and combined with other modalities, offers a new direction in hyperthermia cancer therapy via improved tumor targeting and an improved therapeutic ratio. Our preliminary studies have demonstrated tumor cell cytotoxicity (in vitro and in vivo) with IONP heat and cisplatinum (CDDP) doses lower than those necessary when using conventional heating techniques or cisplatinum alone. Ongoing studies suggest such treatment could be further improved through the use of targeted nanoparticles.

  19. Synthesis of Monodisperse Iron Oxide Nanoparticles without Surfactants

    Directory of Open Access Journals (Sweden)

    Xiao-Chen Yang

    2014-01-01

    Full Text Available Monodisperse iron oxide nanoparticles could be successfully synthesized with two kinds of precipitants through a precipitation method. As-prepared nanoparticles in the size around 10 nm with regular spherical-like shape were achieved by adjusting pH values. NaOH and NH3·H2O were used as two precipitants for comparison. The average size of nanoparticles with NH3·H2O precipitant got smaller and represented better dispersibility, while nanoparticles with NaOH precipitant represented better magnetic property. This work provided a simple method without using any organic solvents, organic metal salts, or surfactants which could easily obtain monodisperse nanoparticles with tunable morphology.

  20. Superparamagnetic iron oxide nanoparticles (SPIONs) for targeted drug delivery

    Science.gov (United States)

    Garg, Vijayendra K.; Kuzmann, Erno; Sharma, Virender K.; Kumar, Arun; Oliveira, Aderbal C.

    2016-10-01

    Studies of superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively carried out. Since the earlier work on Mössbauer studies on SPIONs in 1970s, many biomedical applications and their uses in innovative methods to produce new materials with improved performance have appeared. Applications of SPIONs in environmental remediation are also forthcoming. Several different methods of synthesis and coating of the magnetic particles have been described in the literature, and Mössbauer spectroscopy has been an important tool in the characterization of these materials. It is quite possible that the interpretation of the Mössbauer spectra might not be entirely correct because the possible presence of maghemite in the end product of SPIONs might not have been taken into consideration. Nanotechnology is an emerging field that covers a wide range of new technologies under development in nanoscale (1 to 100 nano meters) to produce new products and methodology.

  1. Hyperfine interactions associated with iron substitute superconducting oxides

    International Nuclear Information System (INIS)

    Ellis, D.E.; Dunlap, B.D.; Saitovitch, E.B.; Azevedo, I.S.; Scorzelli, R.B.; Kimball, C.W.

    1988-01-01

    Theoretical and experimental Moessbauer spectroscopy studies have been made concerning charge and spin densities and magnetic hyperfine fields (H hf in iron-substituted superconducting oxides. Calculations were carried out in the self-consistent-field embedded cluster model using local density theory (SCF-Xα) with a variational atomic orbital basis. Spectral densities and changes in charge and spin density were monitored around neighboring Cu sites, as well as Fe impurity site, in La 2 Cu 1-x Fe x O 4 and YBa 2 Cu 3-x Fe x O 7-y compounds. Moessbauer isomer shifts (IS), quadrupole splittings (QS) and H hf are obtained by fitting multiline models to the observed spectra and are compared with SCF-Xα results for specific lattice sites. The influence of oxygen vacancies and partial oxygen disorder is modelled and compared with the experimental data on variable oxygen content and disorder. (author)

  2. Magnetic and Mössbauer spectroscopy studies of nanocrystalline iron oxide aerogels

    DEFF Research Database (Denmark)

    Carpenter, E.E.; Long, J.W.; Rolison, D.R.

    2006-01-01

    A sol-gel synthesis was used to produce iron oxide aerogels. These nanocrystalline aerogels have a pore-solid structure similar to silica aerogels but are composed entirely of iron oxides. Mössbauer experiments and x-ray diffraction showed that the as-prepared aerogel is an amorphous or poorly...... crystalline iron oxide, which crystallized as a partially oxidized magnetite during heating in argon. After further heat treatment in air, the nanocrystallites are fully converted to maghemite. The particles are superparamagnetic at high temperatures, but the magnetic properties are strongly influenced...

  3. NMR relaxation induced by iron oxide particles: testing theoretical models.

    Science.gov (United States)

    Gossuin, Y; Orlando, T; Basini, M; Henrard, D; Lascialfari, A; Mattea, C; Stapf, S; Vuong, Q L

    2016-04-15

    Superparamagnetic iron oxide particles find their main application as contrast agents for cellular and molecular magnetic resonance imaging. The contrast they bring is due to the shortening of the transverse relaxation time T 2 of water protons. In order to understand their influence on proton relaxation, different theoretical relaxation models have been developed, each of them presenting a certain validity domain, which depends on the particle characteristics and proton dynamics. The validation of these models is crucial since they allow for predicting the ideal particle characteristics for obtaining the best contrast but also because the fitting of T 1 experimental data by the theory constitutes an interesting tool for the characterization of the nanoparticles. In this work, T 2 of suspensions of iron oxide particles in different solvents and at different temperatures, corresponding to different proton diffusion properties, were measured and were compared to the three main theoretical models (the motional averaging regime, the static dephasing regime, and the partial refocusing model) with good qualitative agreement. However, a real quantitative agreement was not observed, probably because of the complexity of these nanoparticulate systems. The Roch theory, developed in the motional averaging regime (MAR), was also successfully used to fit T 1 nuclear magnetic relaxation dispersion (NMRD) profiles, even outside the MAR validity range, and provided a good estimate of the particle size. On the other hand, the simultaneous fitting of T 1 and T 2 NMRD profiles by the theory was impossible, and this occurrence constitutes a clear limitation of the Roch model. Finally, the theory was shown to satisfactorily fit the deuterium T 1 NMRD profile of superparamagnetic particle suspensions in heavy water.

  4. A Holistic Model That Physicochemically Links Iron Oxide - Apatite and Iron Oxide - Copper - Gold Deposits to Magmas

    Science.gov (United States)

    Simon, A. C.; Reich, M.; Knipping, J.; Bilenker, L.; Barra, F.; Deditius, A.; Lundstrom, C.; Bindeman, I. N.

    2015-12-01

    Iron oxide-apatite (IOA) and iron oxide-copper-gold deposits (IOCG) are important sources of their namesake metals and increasingly for rare earth metals in apatite. Studies of natural systems document that IOA and IOCG deposits are often spatially and temporally related with one another and coeval magmatism. However, a genetic model that accounts for observations of natural systems remains elusive, with few observational data able to distinguish among working hypotheses that invoke meteoric fluid, magmatic-hydrothermal fluid, and immiscible melts. Here, we use Fe and O isotope data and high-resolution trace element (e.g., Ti, V, Mn, Al) data of individual magnetite grains from the world-class Los Colorados (LC) IOA deposit in the Chilean Iron Belt to elucidate the origin of IOA and IOCG deposits. Values of d56Fe range from 0.08‰ to 0.26‰, which are within the global range of ~0.06‰ to 0.5‰ for magnetite formed at magmatic conditions. Values of δ18O for magnetite and actinolite are 2.04‰ and 6.08‰, respectively, consistent with magmatic values. Ti, V, Al, and Mn are enriched in magnetite cores and decrease systematically from core to rim. Plotting [Al + Mn] vs. [Ti + V] indicates that magnetite cores are consistent with magmatic and/or magmatic-hydrothermal (i.e., porphyry) magnetites. Decreasing Al, Mn, Ti, V is consistent with a cooling trend from porphyry to Kiruna to IOCG systems. The data from LC are consistent with the following new genetic model for IOA and IOCG systems: 1) magnetite cores crystallize from silicate melt; 2) these magnetite crystals are nucleation sites for aqueous fluid that exsolves and scavenges inter alia Fe, P, S, Cu, Au from silicate melt; 3) the magnetite-fluid suspension is less dense that the surrounding magma, allowing ascent; 4) as the suspension ascends, magnetite grows in equilibrium with the fluid and takes on a magmatic-hydrothermal character (i.e., lower Al, Mn, Ti, V); 5) during ascent, magnetite, apatite and

  5. Environmental Factors Affecting Ammonium Oxidation Under Iron Reducing Conditions

    Science.gov (United States)

    Jaffe, P. R.; Huang, S.; Ruiz-Urigüen, M.

    2014-12-01

    Ammonium (NH4+) oxidation coupled to iron (Fe) reduction in the absence of oxygen and nitrate/nitrite (NO3-/NO2-) has been reported by several investigators and referred to as Feammox. Feammox is a biological reaction, where Fe(III) is the electron acceptor, which is reduced to Fe(II), and NH4+ is the electron donor, which is oxidized to NO2-. Through a 180-day anaerobic incubation experiment, and using PCR-DGGE, 454-pyosequecing and qPCR analysis, we have shown that an Acidimicrobiaceae bacterium A6, a previously unreported species in the Acidimicrobiaceae family, might be either responsible or plays a key role in the Feammox process, We have enriched these Feammox bacteria (65.8% in terms of cell numbers) in a membrane reactor, and isolated the pure Acidimicrobiaceae bacterium A6 strain in an autotrophic medium. In samples collected and then incubated from a series of local wetland-, upland-, as well as storm-water detention pond-sediments, Feammox activity was only detected in acidic soil environments that contain Fe oxides. Using primers we developed for this purpose, Acidimicrobiaceae bacterium A6 was detected in all incubations where Feammox was observed. Anaerobic incubations of Feammox enrichment cultures adjusted to different pH, revealed that the optimal pH for Feammox is 4 ~ 5, and the reaction does not proceed when pH > 7. Feammox was still proceeding at pH as low as 2. In Feammox culture amended with different Fe(III) sources, Feammox reaction proceeded only when Fe oxides (ferrihydrite or goethite ) were supplied, whereas samples incubated with ferric chloride or ferric citrate showed no measurable NH4+ oxidation. Furthermore, we have also determined from incubation experiments conducted with a temperature gradient (10 ~ 35℃), that the Feammox process was active when the temperature is above 15℃, and the optimal temperature is 20℃. Incubations of enrichment culture with 79% Feammox bacteria appeared to remove circa 8% more NH4+ at 20ºC than at

  6. Crystal Structure of Mammalian Cysteine dioxygenase: A Novel Mononuclear Iron Center for Cysteine Thiol Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Simmons,C.; Liu, Q.; Huang, Q.; Hao, Q.; Begley, T.; Karplus, P.; Stipanuk, M.

    2006-01-01

    Cysteine dioxygenase is a mononuclear iron-dependent enzyme responsible for the oxidation of cysteine with molecular oxygen to form cysteinesulfinate. This reaction commits cysteine to either catabolism to sulfate and pyruvate or to the taurine biosynthetic pathway. Cysteine dioxygenase is a member of the cupin superfamily of proteins. The crystal structure of recombinant rat cysteine dioxygenase has been determined to 1.5 Angstroms resolution, and these results confirm the canonical cupin {beta}-sandwich fold and the rare cysteinyl-tyrosine intramolecular crosslink (between Cys93 and Tyr157) seen in the recently reported murine cysteine dioxygenase structure. In contrast to the catalytically inactive mononuclear Ni(II) metallocenter present in the murine structure, crystallization of a catalytically competent preparation of rat cysteine dioxygenase revealed a novel tetrahedrally coordinated mononuclear iron center involving three histidines (His86, His88, and His140) and a water molecule. Attempts to acquire a structure with bound ligand using either co-crystallization or soaks with cysteine revealed the formation of a mixed disulfide involving Cys164 near the active site, which may explain previously observed substrate inhibition. This work provides a framework for understanding the molecular mechanisms involved in thiol dioxygenation and sets the stage for exploring the chemistry of both the novel mononuclear iron center and the catalytic role of the cysteinyl-tyrosine linkage.

  7. Ultrasonic-assisted synthesis and magnetic studies of iron oxide/MCM-41 nanocomposite

    International Nuclear Information System (INIS)

    Ursachi, Irina; Vasile, Aurelia; Ianculescu, Adelina; Vasile, Eugeniu; Stancu, Alexandru

    2011-01-01

    Highlights: → A quick and facile route for the synthesis of iron oxide/MCM-41 nanocomposite. → Magnetic nanoparticles were stabilized inside the pores of mesoporous silica MCM-41. → The pore size of MCM-41 dictates the properties of iron oxide nanoparticles. → The procedure provides a narrow size distribution of magnetic nanoparticles. - Abstract: Iron oxide nanoparticles were stabilized within the pores of mesoporous silica MCM-41 amino-functionalized by a sonochemical method. Formation of iron oxide nanoparticles inside the mesoporous channels of amino-functionalized MCM-41 was realized by wet impregnation using iron nitrate, followed by calcinations at 550 deg. C in air. The effect of functionalization level on structural and magnetic properties of obtained nanocomposites was studied. The resulting materials were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy and selected area electron diffraction (HRTEM and SAED), vibrating sample and superconducting quantum interface magnetometers (VSM and SQUID) and nitrogen adsorption-desorption isotherms measurements. The HRTEM images reveal that the most of the iron oxide nanoparticles were dispersed inside the mesopores of silica matrix and the pore diameter of the amino-functionalized MCM-41 matrix dictates the particle size of iron oxide nanoparticles. The obtained material possesses mesoporous structure and interesting magnetic properties. Saturation magnetization value of magnetic iron oxide nanopatricles stabilized in MCM-41 amino-functionalized by in situ sonochemical synthesis was 1.84 emu g -1 . An important finding is that obtained magnetic nanocomposite materials exhibit enhanced magnetic properties than those of iron oxide/MCM-41 nanocomposite obtained by conventional method. The described method is providing a rather short preparation time and a narrow size distribution of iron oxide nanoparticles.

  8. Morphology and phase structures of CW laser-induced oxide layers on iron surface with evolving reflectivity and colors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Taotao, E-mail: wutaotao@nint.ac.cn; Wang, Lijun; Wei, Chenghua; Zhou, Menglian; He, Minbo; Wu, Lixiong

    2016-11-30

    Highlights: • Firstly, iron samples with different color features were obtained by continuous wave laser irradiation depending on progressive durations. The real-time reflectivity and temperature of samples were measured. The color and the reflectivity evolution were related. They were both caused by the forming oxide films. • Secondly, laser-induced oxidation process of iron was studied by microscope, X-ray diffraction and Raman spectrum. 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. • Lastly, the laser-induced oxide films were thin, orientated and badly crystallized. The Wagner oxidation theory was incapable of describing the non-isothermal and early stage oxidation process. So we emphasized that a precise oxidation model depending on the experiment and the optical constants of the laser-induced oxides must be studied. - Abstract: 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/cm{sup 2}. 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

  9. Preparation and quality test of superparamagnetic iron oxide labeled antisense oligodeoxynucleotide probe: a preliminary study.

    Science.gov (United States)

    Wen, Ming; Li, Bibo; Ouyang, Yu; Luo, Yi; Li, Shaolin

    2009-06-01

    Molecular imaging of tumor antisense gene techniques have been applied to the study of magnetic resonance (MR) gene imaging associated with malignant tumors. In this study, we designed, synthesized, and tested a novel molecular probe, in which the antisense oligodeoxynucleotide (ASODN) was labeled with superparamagnetic iron oxide (SPIO), and its efficiency was examined by in vitro MR imaging after SK-Br-3 mammary carcinoma cell lines (oncocytes) transfection. The SPIO-labeled ASODN probe was prepared through SPIO conjugated to ASODN using a chemical cross linking method. Its morphology and size were detected by atomic force microscope, size distribution were detected by laser granulometer, the conjugating rate and biological activity were determined by high performance liquid chromatography, and the stability was determined by polyacrylamide gel electrophoresis. After that, the probes were transfected into the SK-Br-3 oncocytes, cellular iron uptake was analyzed qualitatively at light and electron microscopy and was quantified at atomic absorption spectrometry, and the signal change of the transfected cells was observed and measured using MR imaging. The morphology of the SPIO-labeled ASODN probe was mostly spherical with well-distributed scattering, and the diameters were between 25 and 40 nm (95%) by atomic force microscope and laser granulometer, the conjugating rate of the probe was 99%. Moreover, this probe kept its activity under physiological conditions and could conjugate with antisense oligodeoxynucleotide. In addition, light microscopy revealed an intracellular uptake of iron oxides in the cytosol and electron microscopic studies revealed a lysosomal deposition of iron oxides in the transfected SK-Br-3 oncocytes by antisense probes, some of them gathered stacks, and the iron content of the group of transfected SK-Br-3 oncocytes by antisense probe is significantly higher (18.37 +/- 0.42 pg) than other contrast groups, the MR imaging showed that

  10. Effect of oxidative stress induced by intracranial iron overload on central pain after spinal cord injury.

    Science.gov (United States)

    Meng, Fan Xing; Hou, Jing Ming; Sun, Tian Sheng

    2017-02-08

    Central pain (CP) is a common clinical problem in patients with spinal cord injury (SCI). Recent studies found the pathogenesis of CP was related to the remodeling of the brain. We investigate the roles of iron overload and subsequent oxidative stress in the remodeling of the brain after SCI. We established a rat model of central pain after SCI. Rats were divided randomly into four groups: SCI, sham operation, SCI plus deferoxamine (DFX) intervention, and SCI plus nitric oxide synthase (NOS) inhibitor treatment. Pain behavior was observed and thermal pain threshold was measured regularly, and brain levels of iron, transferrin receptor 1 (TfR1), ferritin (Fn), and lactoferrin (Lf), were detected in the different groups 12 weeks after establishment of the model. Rats demonstrated self-biting behavior after SCI. Furthermore, the latent period of thermal pain was reduced and iron levels in the hind limb sensory area, hippocampus, and thalamus increased after SCI. Iron-regulatory protein (IRP) 1 levels increased in the hind limb sensory area, while Fn levels decreased. TfR1 mRNA levels were also increased and oxidative stress was activated. Oxidative stress could be inhibited by ferric iron chelators and NOS inhibitors. SCI may cause intracranial iron overload through the NOS-iron-responsive element/IRP pathway, resulting in central pain mediated by the oxidative stress response. Iron chelators and oxidative stress inhibitors can effectively relieve SCI-associated central pain.

  11. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature

    OpenAIRE

    Lili Zhang; Xinxin Yu; Hongrui Hu; Yang Li; Mingzai Wu; Zhongzhu Wang; Guang Li; Zhaoqi Sun; Changle Chen

    2015-01-01

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4?7H2O. By adjusting reaction temperature, ?-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from ?-Fe2O3 to Fe3O4 via ?-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide ...

  12. Biological iron oxidation by Gallionella spp. in drinking water production under fully aerated conditions.

    Science.gov (United States)

    de Vet, W W J M; Dinkla, I J T; Rietveld, L C; van Loosdrecht, M C M

    2011-11-01

    Iron oxidation under neutral conditions (pH 6.5-8) may be a homo- or heterogeneous chemically- or a biologically-mediated process. The chemical oxidation is supposed to outpace the biological process under slightly alkaline conditions (pH 7-8). The iron oxidation kinetics and growth of Gallionella spp. - obligatory chemolithotrophic iron oxidizers - were assessed in natural, organic carbon-containing water, in continuous lab-scale reactors and full-scale groundwater trickling filters in the Netherlands. From Gallionella cell numbers determined by qPCR, balances were made for all systems. The homogeneous chemical iron oxidation occurred in accordance with the literature, but was retarded by a low water temperature (13 °C). The contribution of the heterogeneous chemical oxidation was, despite the presence of freshly formed iron oxyhydroxides, much lower than in previous studies in ultrapure water. This could be caused by the adsorption of natural organic matter (NOM) on the iron oxide surfaces. In the oxygen-saturated natural water with a pH ranging from 6.5 to 7.7, Gallionella spp. grew uninhibited and biological iron oxidation was an important, and probably the dominant, process. Gallionella growth was not even inhibited in a full-scale filter after plate aeration. From this we conclude that Gallionella spp. can grow under neutral pH and fully aerated conditions when the chemical iron oxidation is retarded by low water temperature and inhibition of the autocatalytic iron oxidation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Effect of Iron Enriched Bread Intake on the Oxidative Stress Indices in Male Wistar Rats

    Directory of Open Access Journals (Sweden)

    Sharareh Heidari

    2016-08-01

    Full Text Available Background Contrary to the proven benefits of iron, few concerns in producing the oxidative stress is remained problematic. Objectives The aim of the study was to evaluate the oxidative stress in the male Wistar rats fed bread supplemented with iron in different doses i.e., 35 (basic, 70 (two fold, 140 (four fold, and 210 mg/kg (six fold with or without NaHCO3 (250 mg/kg. Methods In this experimental study Iron, ceruloplasmin, ferritin, total iron binding capacity (TIBC, albumin, total protein, uric acid and plasma superoxide dismutase (SOD, glutathione peroxidase (GPX, catalase (CAT, malondialdehyde (MDA, and total antioxidant capacity (TAC, were evaluated in 30 rats at the first and last day of the experiment (day 30. In addition, phytic acid levels were detected in all baked breads. The data were analyzed by ANOVA and t test procedure though SPSS statistical software version 20. Results Serum iron level in rats that received basic level of iron plus NaHCO3 decreased significantly in the last day of the trial. Higher level of serum iron was seen in rats that received iron twofold, fourfold and sixfold and rats that received iron fourfold plus NaHCO3. Serum ceruloplasmin and ferritin in groups of rats that received fourfold level of iron plus NaHCO3 and rats that received iron sixfold showed a significant increase (P ≤ 0.05. Serum total protein and uric acid in rats that received basic level of iron plus NaHCO3 and rats that received twofold level of iron showed a significant decrease. Serum total protein levels in rats that received fourfold level of iron showed a significant decrease. Bread with NaHCO3 showed higher phytic acid levels than other groups. Conclusions These results indicate that oxidative stress was not induced, whereas some antioxidant activities were significantly changed in rats that received iron-enriched bread.

  14. Iron Oxide as an Mri Contrast Agent for Cell Tracking: Supplementary Issue

    Directory of Open Access Journals (Sweden)

    Daniel J. Korchinski

    2015-01-01

    Full Text Available Iron oxide contrast agents have been combined with magnetic resonance imaging for cell tracking. In this review, we discuss coating properties and provide an overview of ex vivo and in vivo labeling of different cell types, including stem cells, red blood cells, and monocytes/macrophages. Furthermore, we provide examples of applications of cell tracking with iron contrast agents in stroke, multiple sclerosis, cancer, arteriovenous malformations, and aortic and cerebral aneurysms. Attempts at quantifying iron oxide concentrations and other vascular properties are examined. We advise on designing studies using iron contrast agents including methods for validation.

  15. Uncoupling and oxidative stress in liver mitochondria isolated from rats with acute iron overload

    Energy Technology Data Exchange (ETDEWEB)

    Pardo Andreu, G.L. [Centro de Quimica Farmaceutica, Departamento de Investigaciones Biomedicas, Ciudad de La Habana (Cuba); Inada, N.M.; Vercesi, A.E. [Universidade Estadual de Campinas, Departamento de Patologia Clinica, Faculdade de Ciencias Medicas, Campinas, SP (Brazil); Curti, C. [Universidade de Sao Paulo, Departamento de Fisica e Quimica, Faculdade de Ciencias Farmaceuticas de Ribeirao Preto, SP (Brazil)

    2009-01-15

    One hypothesis for the etiology of cell damage arising from iron overload is that its excess selectively affects mitochondria. Here we tested the effects of acute iron overload on liver mitochondria isolated from rats subjected to a single dose of i.p. 500 mg/kg iron-dextran. The treatment increased the levels of iron in mitochondria (from 21{+-}4 to 130{+-}7 nmol/mg protein) and caused both lipid peroxidation and glutathione oxidation. The mitochondria of iron-treated rats showed lower respiratory control ratio in association with higher resting respiration. The mitochondrial uncoupling elicited by iron-treatment did not affect the phosphorylation efficiency or the ATP levels, suggesting that uncoupling is a mitochondrial protective mechanism against acute iron overload. Therefore, the reactive oxygen species (ROS)/H{sup +} leak couple, functioning as a mitochondrial redox homeostatic mechanism could play a protective role in the acutely iron-loaded mitochondria. (orig.)

  16. Single-cell nanotoxicity assays of superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Eustaquio, Trisha; Leary, James F

    2012-01-01

    Properly evaluating the nanotoxicity of nanoparticles involves much more than bulk-cell assays of cell death by necrosis. Cells exposed to nanoparticles may undergo repairable oxidative stress and DNA damage or be induced into apoptosis. Exposure to nanoparticles may cause the cells to alter their proliferation or differentiation or their cell-cell signaling with neighboring cells in a tissue. Nanoparticles are usually more toxic to some cell subpopulations than others, and toxicity often varies with cell cycle. All of these facts dictate that any nanotoxicity assay must be at the single-cell level and must try whenever feasible and reasonable to include many of these other factors. Focusing on one type of quantitative measure of nanotoxicity, we describe flow and scanning image cytometry approaches to measuring nanotoxicity at the single-cell level by using a commonly used assay for distinguishing between necrotic and apoptotic causes of cell death by one type of nanoparticle. Flow cytometry is fast and quantitative, provided that the cells can be prepared into a single-cell suspension for analysis. But when cells cannot be put into suspension without altering nanotoxicity results, or if morphology, attachment, and stain location are important, a scanning image cytometry approach must be used. Both methods are described with application to a particular type of nanoparticle, a superparamagnetic iron oxide nanoparticle (SPION), as an example of how these assays may be applied to the more general problem of determining the effects of nanomaterial exposure to living cells.

  17. Observational evidence of crystalline iron oxides on Mars

    International Nuclear Information System (INIS)

    Bell, J.F. III; McCord, T.B.; Owensby, P.D.

    1990-01-01

    Visible to near-IR (0.4-1.0 μm) spectral reflectance observations of Mars during the 1988 opposition were performed at Mauna Kea Observatory using a circular variable filter spectrometer at a spectral resolution R = λ/Δλ ∼ 80. On August 13 and 14 1988, UT, 41 regions 500-600 km in diameter were observed on Mars. The data have been reduced both to reflectance relative to solar analog (Mars/16 Cyg B) and to relative reflectance (spot/spot). The spectra show the strong near-UV reflectance dropoff characteristic of Mars as well as absorptions at 0.62-0.72 μm and 0.81-0.94 μm both seen here clearly for the first time. These absorption features are interpreted as Fe 3+ electronic transition bands that indicate the presence of crystalline ferric oxide or hydroxide minerals on the Martian surface. Comparison of these data with laboratory spectra obtained by other workers supports the conclusion that a single iron oxide phase, most likely hematite, could account for all of the observed spectral behavior of the Martian surface soils and airborne dust in the 0.4-1.0 μm region. This possibility must be reconciled with data from other possible spectral analogs and other wavelength regions as well as geochemical and mineral stability considerations to arrive at a more complete understanding of the role of ferric minerals in Martian surface mineralogy and weathering

  18. Evaluation of the properties of iron oxide-filled castor oil polyurethane

    Directory of Open Access Journals (Sweden)

    Eleonora Mussatti

    2013-02-01

    Full Text Available The aim of this study was to obtain and evaluate the electrical, thermal and mechanical properties of iron oxide-filled castor oil polyurethane (PU/Fe2O3. The iron oxide used in this study was a residue derived from the steel pickling process of a Brazilian steel rolling industry. Polymeric composites with different iron oxide volume fractions (2.5, 5.0, 7.5, 10.0 and 12.5% were prepared through the casting process followed by compression molding at room temperature. The composites were analyzed by FTIR, XRD and densities, tensile strength, Young's modulus, electrical and thermal conductivities measurements. By increasing the iron oxide content, the apparent density, tensile strength, Young's modulus and electrical conductivity values of the composites were also increased. The iron oxide additions did not change significantly the value of thermal conductivity (from 0.191 W.mK-1 for PU up to 0.340 W.mK-1 for PU enriched with 12.5% v/v of iron oxide. Thus, even at the higher iron oxide concentration, the compounds as well as the pure polyurethane can be classified as thermal insulators.

  19. Inhibitory Effect Evaluation of Glycerol-Iron Oxide Thin Films on Methicillin-Resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    C. L. Popa

    2015-01-01

    Full Text Available The main purpose of this study was to evaluate the inhibitory effect of glycerol- iron oxide thin films on Methicillin-Resistant Staphylococcus aureus (MRSA. Our results suggest that glycerol-iron oxide thin films could be used in the future for various biomedical and pharmaceutical applications. The glycerol-iron oxide thin films have been deposited by spin coating method on a silicon (111 substrate. The structural properties have been studied by X-ray diffraction (XRD and scanning electron spectroscopy (SEM. The XRD investigations of the prepared thin films demonstrate that the crystal structure of glycerol-iron oxide nanoparticles was not changed after spin coating deposition. On the other hand, the SEM micrographs suggest that the size of the glycerol-iron oxide microspheres increased with the increase of glycerol exhibiting narrow size distributions. The qualitative depth profile of glycerol-iron oxide thin films was identified by glow discharge optical emission spectroscopy (GDOES. The GDOES spectra revealed the presence of the main elements: Fe, O, C, H, and Si. The antimicrobial activity of glycerol-iron oxide thin films was evaluated by measuring the zone of inhibition. After 18 hours of incubation at 37°C, the diameters of the zones of complete inhibition have been measured obtaining values around 25 mm.

  20. Evaluation of the Properties of Iron Oxide-Filled Castor Oil Polyurethane

    Directory of Open Access Journals (Sweden)

    Eleonora Mussatti

    2012-01-01

    Full Text Available The aim of this study was to obtain and evaluate the electrical, thermal and mechanical properties of iron oxide-filled castor oil polyurethane (PU/Fe2O3. The iron oxide used in this study was a residue derived from the steel pickling process of a Brazilian steel rolling industry. Polymeric composites with different iron oxide volume fractions (2.5, 5.0, 7.5, 10.0 and 12.5% were prepared through the casting process followed by compression molding at room temperature. The composites were analyzed by FTIR, XRD and densities, tensile strength, Young's modulus, electrical and thermal conductivities measurements. By increasing the iron oxide content, the apparent density, tensile strength, Young's modulus and electrical conductivity values of the composites were also increased. The iron oxide additions did not change significantly the value of thermal conductivity (from 0.191 W.mK-1 for PU up to 0.340 W.mK-1 for PU enriched with 12.5% v/v of iron oxide. Thus, even at the higher iron oxide concentration, the compounds as well as the pure polyurethane can be classified as thermal insulators.

  1. Concentration-dependent toxicity of iron oxide nanoparticles mediated by increased oxidative stress

    Directory of Open Access Journals (Sweden)

    Saba Naqvi

    2010-11-01

    Full Text Available Saba Naqvi1, Mohammad Samim2, MZ Abdin3, Farhan Jalees Ahmed4, AN Maitra5, CK Prashant6, Amit K Dinda61Faculty of Engineering and Interdisciplinary Sciences, 2Department of Chemistry, 3Department of Biotechnology, Faculty of Science, 4Department of Pharmaceutics, Faculty of Pharmacy, Jamia Hamdard, Hamdard University, 5Department of Chemistry, University of Delhi, 6Department of Pathology, All India Institute of Medical Sciences, New Delhi, IndiaAbstract: Iron oxide nanoparticles with unique magnetic properties have a high potential for use in several biomedical, bioengineering and in vivo applications, including tissue repair, magnetic resonance imaging, immunoassay, drug delivery, detoxification of biologic fluids, cell sorting, and hyperthermia. Although various surface modifications are being done for making these nonbiodegradable nanoparticles more biocompatible, their toxic potential is still a major concern. The current in vitro study of the interaction of superparamagnetic iron oxide nanoparticles of mean diameter 30 nm coated with Tween 80 and murine macrophage (J774 cells was undertaken to evaluate the dose- and time-dependent toxic potential, as well as investigate the role of oxidative stress in the toxicity. A 15–30 nm size range of spherical nanoparticles were characterized by transmission electron microscopy and zeta sizer. MTT assay showed >95% viability of cells in lower concentrations (25–200 µg/mL and up to three hours of exposure, whereas at higher concentrations (300–500 µg/mL and prolonged (six hours exposure viability reduced to 55%–65%. Necrosis-apoptosis assay by propidium iodide and Hoechst-33342 staining revealed loss of the majority of the cells by apoptosis. H2DCFDDA assay to quantify generation of intracellular reactive oxygen species (ROS indicated that exposure to a higher concentration of nanoparticles resulted in enhanced ROS generation, leading to cell injury and death. The cell membrane injury

  2. Chronic Iron Limitation Confers Transient Resistance to Oxidative Stress in Marine Diatoms1

    Science.gov (United States)

    Graff van Creveld, Shiri; Rosenwasser, Shilo; Vardi, Assaf

    2016-01-01

    Diatoms are single-celled, photosynthetic, bloom-forming algae that are responsible for at least 20% of global primary production. Nevertheless, more than 30% of the oceans are considered “ocean deserts” due to iron limitation. We used the diatom Phaeodactylum tricornutum as a model system to explore diatom’s response to iron limitation and its interplay with susceptibility to oxidative stress. By analyzing physiological parameters and proteome profiling, we defined two distinct phases: short-term (5 d, phase II) iron limitation. While at phase I no significant changes in physiological parameters were observed, molecular markers for iron starvation, such as Iron Starvation Induced Protein and flavodoxin, were highly up-regulated. At phase II, down-regulation of numerous iron-containing proteins was detected in parallel to reduction in growth rate, chlorophyll content, photosynthetic activity, respiration rate, and antioxidant capacity. Intriguingly, while application of oxidative stress to phase I and II iron-limited cells similarly oxidized the reduced glutathione (GSH) pool, phase II iron limitation exhibited transient resistance to oxidative stress, despite the down regulation of many antioxidant proteins. By comparing proteomic profiles of P. tricornutum under iron limitation and metatranscriptomic data of an iron enrichment experiment conducted in the Pacific Ocean, we propose that iron-limited cells in the natural environment resemble the phase II metabolic state. These results provide insights into the trade-off between optimal growth rate and susceptibility to oxidative stress in the response of diatoms to iron quota in the marine environment. PMID:27503604

  3. Iron supplementation at high altitudes induces inflammation and oxidative injury to lung tissues in rats

    Energy Technology Data Exchange (ETDEWEB)

    Salama, Samir A., E-mail: salama.3@buckeyemail.osu.edu [High Altitude Research Center, Taif University, Al-Haweiah, Taif 21974 (Saudi Arabia); Department of Biochemistry, Faculty of Pharmacy, Al-Azhar University, Cairo 11751 (Egypt); Department of Pharmacology and GTMR Unit, College of Clinical Pharmacy, Taif University, Al-Haweiah, Taif 21974 (Saudi Arabia); Omar, Hany A. [Department of Pharmacology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62514 (Egypt); Maghrabi, Ibrahim A. [Department of Clinical Pharmacy, College of Clinical Pharmacy, Taif University, Al-Haweiah, Taif 21974 (Saudi Arabia); AlSaeed, Mohammed S. [Department of Surgery, College of Medicine, Taif University, Al-Haweiah, Taif 21974 (Saudi Arabia); EL-Tarras, Adel E. [High Altitude Research Center, Taif University, Al-Haweiah, Taif 21974 (Saudi Arabia)

    2014-01-01

    Exposure to high altitudes is associated with hypoxia and increased vulnerability to oxidative stress. Polycythemia (increased number of circulating erythrocytes) develops to compensate the high altitude associated hypoxia. Iron supplementation is, thus, recommended to meet the demand for the physiological polycythemia. Iron is a major player in redox reactions and may exacerbate the high altitudes-associated oxidative stress. The aim of this study was to explore the potential iron-induced oxidative lung tissue injury in rats at high altitudes (6000 ft above the sea level). Iron supplementation (2 mg elemental iron/kg, once daily for 15 days) induced histopathological changes to lung tissues that include severe congestion, dilatation of the blood vessels, emphysema in the air alveoli, and peribronchial inflammatory cell infiltration. The levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), lipid peroxidation product and protein carbonyl content in lung tissues were significantly elevated. Moreover, the levels of reduced glutathione and total antioxidant capacity were significantly reduced. Co-administration of trolox, a water soluble vitamin E analog (25 mg/kg, once daily for the last 7 days of iron supplementation), alleviated the lung histological impairments, significantly decreased the pro-inflammatory cytokines, and restored the oxidative stress markers. Together, our findings indicate that iron supplementation at high altitudes induces lung tissue injury in rats. This injury could be mediated through excessive production of reactive oxygen species and induction of inflammatory responses. The study highlights the tissue injury induced by iron supplementation at high altitudes and suggests the co-administration of antioxidants such as trolox as protective measures. - Highlights: • Iron supplementation at high altitudes induced lung histological changes in rats. • Iron induced oxidative stress in lung tissues of rats at high altitudes. • Iron

  4. Iron supplementation at high altitudes induces inflammation and oxidative injury to lung tissues in rats

    International Nuclear Information System (INIS)

    Salama, Samir A.; Omar, Hany A.; Maghrabi, Ibrahim A.; AlSaeed, Mohammed S.; EL-Tarras, Adel E.

    2014-01-01

    Exposure to high altitudes is associated with hypoxia and increased vulnerability to oxidative stress. Polycythemia (increased number of circulating erythrocytes) develops to compensate the high altitude associated hypoxia. Iron supplementation is, thus, recommended to meet the demand for the physiological polycythemia. Iron is a major player in redox reactions and may exacerbate the high altitudes-associated oxidative stress. The aim of this study was to explore the potential iron-induced oxidative lung tissue injury in rats at high altitudes (6000 ft above the sea level). Iron supplementation (2 mg elemental iron/kg, once daily for 15 days) induced histopathological changes to lung tissues that include severe congestion, dilatation of the blood vessels, emphysema in the air alveoli, and peribronchial inflammatory cell infiltration. The levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), lipid peroxidation product and protein carbonyl content in lung tissues were significantly elevated. Moreover, the levels of reduced glutathione and total antioxidant capacity were significantly reduced. Co-administration of trolox, a water soluble vitamin E analog (25 mg/kg, once daily for the last 7 days of iron supplementation), alleviated the lung histological impairments, significantly decreased the pro-inflammatory cytokines, and restored the oxidative stress markers. Together, our findings indicate that iron supplementation at high altitudes induces lung tissue injury in rats. This injury could be mediated through excessive production of reactive oxygen species and induction of inflammatory responses. The study highlights the tissue injury induced by iron supplementation at high altitudes and suggests the co-administration of antioxidants such as trolox as protective measures. - Highlights: • Iron supplementation at high altitudes induced lung histological changes in rats. • Iron induced oxidative stress in lung tissues of rats at high altitudes. • Iron

  5. Chronic Iron Limitation Confers Transient Resistance to Oxidative Stress in Marine Diatoms.

    Science.gov (United States)

    Graff van Creveld, Shiri; Rosenwasser, Shilo; Levin, Yishai; Vardi, Assaf

    2016-10-01

    Diatoms are single-celled, photosynthetic, bloom-forming algae that are responsible for at least 20% of global primary production. Nevertheless, more than 30% of the oceans are considered "ocean deserts" due to iron limitation. We used the diatom Phaeodactylum tricornutum as a model system to explore diatom's response to iron limitation and its interplay with susceptibility to oxidative stress. By analyzing physiological parameters and proteome profiling, we defined two distinct phases: short-term (chronic (>5 d, phase II) iron limitation. While at phase I no significant changes in physiological parameters were observed, molecular markers for iron starvation, such as Iron Starvation Induced Protein and flavodoxin, were highly up-regulated. At phase II, down-regulation of numerous iron-containing proteins was detected in parallel to reduction in growth rate, chlorophyll content, photosynthetic activity, respiration rate, and antioxidant capacity. Intriguingly, while application of oxidative stress to phase I and II iron-limited cells similarly oxidized the reduced glutathione (GSH) pool, phase II iron limitation exhibited transient resistance to oxidative stress, despite the down regulation of many antioxidant proteins. By comparing proteomic profiles of P. tricornutum under iron limitation and metatranscriptomic data of an iron enrichment experiment conducted in the Pacific Ocean, we propose that iron-limited cells in the natural environment resemble the phase II metabolic state. These results provide insights into the trade-off between optimal growth rate and susceptibility to oxidative stress in the response of diatoms to iron quota in the marine environment. © 2016 American Society of Plant Biologists. All Rights Reserved.

  6. Dominance of sulfur-fueled iron oxide reduction in low-sulfate freshwater sediments.

    Science.gov (United States)

    Hansel, Colleen M; Lentini, Chris J; Tang, Yuanzhi; Johnston, David T; Wankel, Scott D; Jardine, Philip M

    2015-11-01

    A central tenant in microbial biogeochemistry is that microbial metabolisms follow a predictable sequence of terminal electron acceptors based on the energetic yield for the reaction. It is thereby oftentimes assumed that microbial respiration of ferric iron outcompetes sulfate in all but high-sulfate systems, and thus sulfide has little influence on freshwater or terrestrial iron cycling. Observations of sulfate reduction in low-sulfate environments have been attributed to the presumed presence of highly crystalline iron oxides allowing sulfate reduction to be more energetically favored. Here we identified the iron-reducing processes under low-sulfate conditions within columns containing freshwater sediments amended with structurally diverse iron oxides and fermentation products that fuel anaerobic respiration. We show that despite low sulfate concentrations and regardless of iron oxide substrate (ferrihydrite, Al-ferrihydrite, goethite, hematite), sulfidization was a dominant pathway in iron reduction. This process was mediated by (re)cycling of sulfur upon reaction of sulfide and iron oxides to support continued sulfur-based respiration--a cryptic sulfur cycle involving generation and consumption of sulfur intermediates. Although canonical iron respiration was not observed in the sediments amended with the more crystalline iron oxides, iron respiration did become dominant in the presence of ferrihydrite once sulfate was consumed. Thus, despite more favorable energetics, ferrihydrite reduction did not precede sulfate reduction and instead an inverse redox zonation was observed. These findings indicate that sulfur (re)cycling is a dominant force in iron cycling even in low-sulfate systems and in a manner difficult to predict using the classical thermodynamic ladder.

  7. Secoisolariciresinol diglucoside abrogates oxidative stress-induced damage in cardiac iron overload condition.

    Directory of Open Access Journals (Sweden)

    Stephanie Puukila

    Full Text Available Cardiac iron overload is directly associated with cardiac dysfunction and can ultimately lead to heart failure. This study examined the effect of secoisolariciresinol diglucoside (SDG, a component of flaxseed, on iron overload induced cardiac damage by evaluating oxidative stress, inflammation and apoptosis in H9c2 cardiomyocytes. Cells were incubated with 50 μ5M iron for 24 hours and/or a 24 hour pre-treatment of 500 μ M SDG. Cardiac iron overload resulted in increased oxidative stress and gene expression of the inflammatory mediators tumor necrosis factor-α, interleukin-10 and interferon γ, as well as matrix metalloproteinases-2 and -9. Increased apoptosis was evident by increased active caspase 3/7 activity and increased protein expression of Forkhead box O3a, caspase 3 and Bax. Cardiac iron overload also resulted in increased protein expression of p70S6 Kinase 1 and decreased expression of AMP-activated protein kinase. Pre-treatment with SDG abrogated the iron-induced increases in oxidative stress, inflammation and apoptosis, as well as the increased p70S6 Kinase 1 and decreased AMP-activated protein kinase expression. The decrease in superoxide dismutase activity by iron treatment was prevented by pre-treatment with SDG in the presence of iron. Based on these findings we conclude that SDG was cytoprotective in an in vitro model of iron overload induced redox-inflammatory damage, suggesting a novel potential role for SDG in cardiac iron overload.

  8. Arsenic mobility and bioavailability in paddy soil under iron compound amendments at different growth stages of rice.

    Science.gov (United States)

    Yu, Huan-Yun; Wang, Xiangqin; Li, Fangbai; Li, Bin; Liu, Chuanping; Wang, Qi; Lei, Jing

    2017-05-01

    Iron (Fe)-based solids can reduce arsenic (As) mobility and bioavailability in soils, which has been well recognized. However, to our knowledge, there are few studies on As uptake at different growth stages of rice under Fe compound amendments. In addition, the formation of Fe plaques at different growth stages of rice has also been rarely reported. Therefore, the present study was undertaken to investigate As mobility and bioavailability in paddy soil under Fe compound amendments throughout the whole growth stage of rice plants. Amendments of poorly crystalline Fe oxides (PC-Fe), FeCl 2 +NaNO 3 and FeCl 2 reduced grain As by 54% ± 3.0%, 52% ± 3.0% and 46% ± 17%, respectively, compared with that of the non-amended control. The filling stage was suggested to be the key stage to take measures to reduce As uptake. At this stage, all soil amendments significantly reduced As accumulation in rice plants. At the maturation stage, PC-Fe amendment significantly reduced mobile pools and increased immobile pools of soil As. Besides, PC-Fe treatment promoted the transformation of Fe fractions from dissolved Fe to adsorbed, poorly crystalline and free Fe oxides. Moreover, significant positive correlations between soil Fe fractions and As fractions were found. Accordingly, we hypothesized that Fe compound amendments might affect the concentration distribution of Fe fractions first and then affect As fractionation in soil and its bioavailability to rice plants indirectly. The formation of Fe plaques varied with growth stages and different treatments. Significantly negative correlations between mobile pools of As and Fe or As in Fe plaques indicated that Fe plaques could immobilize mobile As in soils and thus affect As bioavailability. Overall, the effect of the soil amendments on reduction of As uptake varied with growth stages and different treatments, and further research on the key stage for reducing As uptake is still required. Copyright © 2017 Elsevier Ltd. All

  9. Effect of Iron Oxides (Ordinary and Nano and Municipal Solid Waste Compost (MSWC Coated Sulfur on Wheat (Triticum aestivum L. Plant Iron Concentration and Growth

    Directory of Open Access Journals (Sweden)

    S Mazaherinia

    2011-02-01

    Full Text Available Abstract A greenhouse study was conducted to compare the effects of ordinary iron oxide (0.02-0.06 mm and nano iron oxide (25-250 nm and five levels of both iron oxides (0, 0.05, 0.1, 0.5, and 1.0 %w/w and two levels of sulfurous granular compost (MSW (0 and 2% w/w on plant height, spike length, grain weight per spike, total plant dry matter weight and thousands grain weight of wheat. The experimental factors were combined in factorial arrangement in a completely randomized design with 3 replications. Results showed that nano iron oxide was superior over ordinary iron oxide in all parameters studied. Fe concentration, spike length, plant height, grain weight per spike, total plant dry weight and thousands grain weight showed increasing trend per increase in both of iron oxides levels. Also, all parameters studied in sulfurous granular compost (MSW treatment were superior over granular compost without sulfurous (MSW. This increase in all parameters were significantly higher when urban solid waste compost coated with sulfur coupled with nano iron oxide compared to urban sulfurous granular compost (MSW along with ordinary iron oxide. Keywords: Sulfurous granular compost (MSW, Nano and ordinary iron oxides, Wheat

  10. Chromium Elimination from Water by use of Iron Oxide Nanoparticles Absorbents

    Directory of Open Access Journals (Sweden)

    S Shokraei

    2014-09-01

    Results: results showed that best absorbent is soil absorbent and iron oxide nanoparticles, with maximum removal percent equal to 96.2%. Also best turnover was obtained from 8837 ppm of primary concentration of heavy metal. In other hand, in other experiments that used from iron oxide nanoparticles, adding of nanoparticles caused to increase in chrome absorption and conversion of Cr6+ to Cr3+. Conclusion: with use of the results of this study can be said that Combining of iron oxide nanoparticles with chrome removal filters can be convert Cr6+ to Cr3+, and process turnover will increased.

  11. Environment friendly route of iron oxide nanoparticles from Zingiber officinale (ginger) root extract

    Science.gov (United States)

    Xin Hui, Yau; Yi Peng, Teoh; Wei Wen, Liu; Zhong Xian, Ooi; Peck Loo, Kiew

    2016-11-01

    Iron oxide nanoparticles were prepared from the reaction between the Zingiber officinale (ginger) root extracts and ferric chloride solution at 50°C for 2 h in mild stirring condition. The synthesized powder forms of nanoparticles were further characterized by using UV-Vis spectroscopy and X-ray Diffraction spectrometry. UV-Vis analysis shows the absorption peak of iron oxide nanoparticles is appeared at 370 nm. The calculation of crystallite size from the XRD showed that the average particle size of iron oxide nanoparticles was 68.43 nm. Therefore, this eco-friendly technique is low cost and large scale nanoparticles synthesis to fulfill the demand of various applications.

  12. Application of Iron Oxide Nano materials for the Removal of Heavy Metals

    International Nuclear Information System (INIS)

    Dave, P.N.; Chopda, L.V.

    2014-01-01

    In the 21st century water polluted by heavy metal is one of the environment problems. Various methods for removal of the heavy metal ions from the water have extensively been studied. Application of iron oxide nana particles based nano materials for removal of heavy metals is well-known adsorbents for remediation of water. Due to its important physiochemical property, inexpensive method and easy regeneration in the presence of external magnetic field make them more attractive toward water purification. Surface modification strategy of iron oxide nanoparticles is also used for the remediation of water increases the efficiency of iron oxide for the removal of the heavy metal ions from the aqueous system.

  13. Magnetothermal release of payload from iron oxide/silica drug delivery agents

    Energy Technology Data Exchange (ETDEWEB)

    Luong, T.T., E-mail: thientai.luong@chem.kuleuven.be [KU Leuven, Department of Chemistry, Celestijnenlaan 200D, Heverlee 3001 (Belgium); Hanoi National University of Education, Faculty of Chemistry, Xuan Thuy 136, Cau Giay, Hanoi (Viet Nam); Knoppe, S.; Bloemen, M.; Brullot, W.; Strobbe, R. [KU Leuven, Department of Chemistry, Celestijnenlaan 200D, Heverlee 3001 (Belgium); Locquet, J.-P. [KU Leuven, Department of Physics, Celestijnenlaan 200D, Heverlee 3001 (Belgium); Verbiest, T. [KU Leuven, Department of Chemistry, Celestijnenlaan 200D, Heverlee 3001 (Belgium)

    2016-10-15

    The release of covalently bound Rhodamine B from iron oxide/mesoporous silica core/shell nanoparticles under magnetically induced heating was studied. The system acts as a model to study drug delivery and payload release under magnetothermal heating. - Graphical abstract: The release of covalently bound Rhodamine B from iron oxide/mesoporous silica core/shell nanoparticles under magnetically induced heating was studied. - Highlights: • Iron oxide/mesoporous-SiO{sub 2} core-shell NPs were synthesized. • The dye was covalently bound to SiO{sub 2} shells. • The release of dye under magnetothermal heating was studied. • The results are relevant for controlled drug release.

  14. Sorption of small amounts of europium(III) on iron(III) hydroxide and oxide

    International Nuclear Information System (INIS)

    Music, S.; Gessner, M.; Wolf, R.H.H.

    1979-01-01

    The sorption of small amounts of europium(III) on iron(III) hydroxide and oxide has been studied as a function of pH. The mechanism of sorption is discussed. Optimum conditions have been found for the preconcentration of small or trace amounts of europium(III) by iron(III) hydroxide and oxide. The influence of complexing agents (EDTA, oxalate, tartrate and 5-sulfosalicylic acid) on the sorption of small amounts of europium(III) on iron(III) oxide has also been studied. (author)

  15. Evaluation of the properties of iron oxide-filled castor oil polyurethane

    OpenAIRE

    Mussatti, Eleonora; Merlini, Claudia; Barra, Guilherme Mariz de Oliveira; Güths, Saulo; Oliveira, Antonio Pedro Novaes de; Siligardi, Cristina

    2012-01-01

    The aim of this study was to obtain and evaluate the electrical, thermal and mechanical properties of iron oxide-filled castor oil polyurethane (PU/Fe2O3). The iron oxide used in this study was a residue derived from the steel pickling process of a Brazilian steel rolling industry. Polymeric composites with different iron oxide volume fractions (2.5, 5.0, 7.5, 10.0 and 12.5%) were prepared through the casting process followed by compression molding at room temperature. The composites were ana...

  16. Physiological effects of magnetic iron oxide nanoparticles towards watermelon.

    Science.gov (United States)

    Li, Junli; Chang, Peter R; Huang, Jin; Wang, Yunqiang; Yuan, Hong; Ren, Hongxuan

    2013-08-01

    Nanoparticles (NPs) have been exploited in a diverse range of products in the past decade or so. However, the biosafety/environmental impact or legislation pertaining to this newly created, highly functional composites containing NPs (otherwise called nanomaterials) is generally lagging behind their technological innovation. To advance the agenda in this area, our current primary interest is focused on using crops as model systems as they have very close relationship with us. Thus, the objective of the present study was to evaluate the biological effects of magnetic iron oxide nanoparticles towards watermelon seedlings. We have systematically studied the physiological effects of Fe2O3 nanoparticles (nano-Fe2O3) on watermelon, and present the first evidence that a significant amount of Fe2O3 nanoparticles suspended in a liquid medium can be taken up by watermelon plants and translocated throughout the plant tissues. Changes in important physiological indicators, such as root activity, activity of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD), chlorophyll and malondialdehyde (MDA) contents, ferric reductase activity, root apoplastic iron content were clearly presented. Different concentrations of nano-Fe2O3 all increased seed germination, seedling growth, and enhanced physiological function to some degree; and the positive effects increased quickly and then slowed with an increase in the treatment concentrations. Changes in CAT, SOD and POD activities due to nano-Fe2O3 were significantly larger than that of the control. The 20 mg/L treatment had the most obvious effect on the increase of root activity. Ferric reductase activity, root apoplastic iron content, and watermelon biomass were significantly affected by exposure to nano-Fe2O3. Results of statistical analysis showed that there were significant differences in all the above indexes between the treatment at optimal concentration and the control. This proved that the proper concentration of nano

  17. Iron overload by Superparamagnetic Iron Oxide Nanoparticles is a High Risk Factor in Cirrhosis by a Systems Toxicology Assessment

    Science.gov (United States)

    Wei, Yushuang; Zhao, Mengzhu; Yang, Fang; Mao, Yang; Xie, Hang; Zhou, Qibing

    2016-06-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent have been widely used in magnetic resonance imaging for tumor diagnosis and theranostics. However, there has been safety concern of SPIONs with cirrhosis related to excess iron-induced oxidative stress. In this study, the impact of iron overload by SPIONs was assessed on a mouse cirrhosis model. A single dose of SPION injection at 0.5 or 5 mg Fe/kg in the cirrhosis group induced a septic shock response at 24 h with elevated serum levels of liver and kidney function markers and extended impacts over 14 days including high levels of serum cholesterols and persistent low serum iron level. In contrast, full restoration of liver functions was found in the normal group with the same dosages over time. Analysis with PCR array of the toxicity pathways revealed the high dose of SPIONs induced significant expression changes of a distinct subset of genes in the cirrhosis liver. All these results suggested that excess iron of the high dose of SPIONs might be a risk factor for cirrhosis because of the marked impacts of elevated lipid metabolism, disruption of iron homeostasis and possibly, aggravated loss of liver functions.

  18. Effect of selective removal of organic matter and iron oxides on the ...

    African Journals Online (AJOL)

    The effect of selective removal of organic matter and amorphous and crystalline iron oxides on N2-BET specific surface areas of some soil clays was evaluated. Clay fractions from 10 kaolinitic tropical soils were successively treated to remove organic matter by oxidation with Na hypochlorite, amorphous Fe oxide with acid ...

  19. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    DEFF Research Database (Denmark)

    Scholz, Florian; Löscher, Carolin; Fiskal, Annika

    2016-01-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface...

  20. Soluble Iron in Alveolar Macrophages Modulates Iron Oxide Particle-Induced Inflammatory Response via Prostaglandin E2 Synthesis

    Science.gov (United States)

    Ambient particulate matter (PM)-associated metals have been shown to play an important role in cardiopulmonary health outcomes. To study the modulation of inflammation by PM-associated soluble metal, we investigated intracellular solubility of radiolabelled iron oxide (59

  1. Iron sulphide containing hydrodesulfurization catalysts : Mössbauer study of the sulfidibility of alpha-iron(III) oxide

    NARCIS (Netherlands)

    Ramselaar, W.L.T.M.; Beer, de V.H.J.; Kraan, van der A.M.

    1988-01-01

    As a first step in the study of the sulphidation of carbon-supported iron oxide catalyst systems the sulphiding of a well-characterized, unsupported model compound, viz. a-Fe2O3(mean particle diameter ca. 50 nm) was investigated using in-situ Mössbauer spectroscopy and the temperature-programmed

  2. Preparation of nano-iron oxide red pigment powders by use of cyanided tailings

    International Nuclear Information System (INIS)

    Li Dengxin; Gao Guolong; Meng Fanling; Ji Chong

    2008-01-01

    On one hand, cyanided tailings are one kind of pollutants. On the other hand, they contain a lot of valuable elements. So utilization of them can bring social and environmental benefits. In this paper, cyanided tailings were used to prepare nano-iron oxide red pigment powders by an ammonia process with urea as precipitant. At first, cyanided tailings were oxidized by nitric acid. Then, the oxidizing mixture was separated into solid and liquid parts. The liquid mixture was reduced by scrap iron and the impurity of it was removed by use of NH 3 .H 2 O. Then, the seed crystal of γ-FeOOH was obtained, when the pure liquid reacted with ammonia liquid at the selected experimental conditions. At last, nano-iron oxide red pigment powders were prepared. The structure, morphology and size distribution of seed crystal and iron oxide red were characterized systematically by means of X-ray diffraction (XRD), transmission electron microscope (TEM) and laser particle size analyzer (LPSA). The results revealed that typical iron oxide nanoparticles were α-Fe 2 O 3 with particle size of 50-70 nm. Furthermore, the factors that affected the hue and quality of the seed crystal and iron oxide red pigment were also discussed

  3. Corrosion Behavior of Pipeline Carbon Steel under Different Iron Oxide Deposits in the District Heating System

    Directory of Open Access Journals (Sweden)

    Yong-Sang Kim

    2017-05-01

    Full Text Available The corrosion behavior of pipeline steel covered by iron oxides (α-FeOOH; Fe3O4 and Fe2O3 was investigated in simulated district heating water. In potentiodynamic polarization tests; the corrosion rate of pipeline steel is increased under the iron oxide but the increaseing rate is different due to the differnet chemical reactions of the covered iron oxides. Pitting corrosion was only observed on the α-FeOOH-covered specimen; which is caused by the crevice corrosion under the α-FeOOH. From Mott-Schottky and X-ray diffraction results; the surface reaction and oxide layer were dependent on the kind of iron oxides. The iron oxides deposit increases the failure risk of the pipeline and localized corrosion can be occurred under the α-FeOOH-covered region of the pipeline. Thus, prevention methods for the iron oxide deposit in the district pipeline system such as filtering or periodic chemical cleaning are needed.

  4. Biocompatible capped iron oxide nanoparticles for Vibrio cholerae detection

    International Nuclear Information System (INIS)

    Sharma, Anshu; Rawat, Kamla; Solanki, Pratima R; Bohidar, H B; Baral, Dinesh

    2015-01-01

    We report the studies relating to fabrication of an efficient immunosensor for Vibrio cholerae detection. Magnetite (iron oxide (Fe 3 O 4 )) nanoparticles (NPs) have been synthesized by the co-precipitation method and capped by citric acid (CA). These NPs were electrophoretically deposited onto indium-tin-oxide (ITO)-coated glass substrate and used for immobilization of monoclonal antibodies against Vibrio cholerae (Ab) and bovine serum albumin (BSA) for Vibrio cholerae detection using an electrochemical technique. The structural and morphological studies of Fe 3 O 4 and CA-Fe 3 O 4 /ITO were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) techniques. The average crystalline size of Fe 3 O 4 , CA-Fe 3 O 4 nanoparticles obtained were about 29 ± 1 nm and 37 ± 1 nm, respectively. The hydrodynamic radius of the nanoparticles was found to be 77.35 nm (Fe 3 O 4 ) and 189.51 nm (CA-Fe 3 O 4 ) by DLS measurement. The results of electrochemical response studies of the fabricated BSA/Ab/CA-Fe 2 O 3 /ITO immunosensor exhibits a good detection range of 12.5–500 ng mL −1 with a low detection limit of 0.32 ng mL −1 , sensitivity 0.03 Ω/ng ml −1 cm −2 , and reproducibility more than 11 times. (paper)

  5. Freezing-Enhanced Dissolution of Iron Oxides: Effects of Inorganic Acid Anions.

    Science.gov (United States)

    Jeong, Daun; Kim, Kitae; Min, Dae Wi; Choi, Wonyong

    2015-11-03

    Dissolution of iron from mineral dust particles greatly depends upon the type and amount of copresent inorganic anions. In this study, we investigated the roles of sulfate, chloride, nitrate, and perchlorate on the dissolution of maghemite and lepidocrocite in ice under both dark and UV irradiation and compared the results with those of their aqueous counterparts. After 96 h of reaction, the total dissolved iron in ice (pH 3 before freezing) was higher than that in the aqueous phase (pH 3) by 6-28 times and 10-20 times under dark and UV irradiation, respectively. Sulfuric acid was the most efficient in producing labile iron under dark condition, whereas hydrochloric acid induced the most dissolution of the total and ferrous iron in the presence of light. This ice-induced dissolution result was also confirmed with Arizona Test Dust (AZTD). In the freeze-thaw cycling test, the iron oxide samples containing chloride, nitrate, or perchlorate showed a similar extent of total dissolved iron after each cycling while the sulfate-containing sample rapidly lost its dissolution activity with repeating the cycle. This unique phenomenon observed in ice might be related to the freeze concentration of protons, iron oxides, and inorganic anions in the liquid-like ice grain boundary region. These results suggest that the ice-enhanced dissolution of iron oxides can be a potential source of bioavailable iron, and the acid anions critically influence this process.

  6. Kinetics and mechanism of oxidation of glycine by iron(III)

    Indian Academy of Sciences (India)

    Kinetics and mechanism of oxidation of glycine by iron(III)-1,10-phenanthroline complex has been studied in perchloric acid medium. The reaction is first order with respect to iron(III) and glycine. An increase in (phenanthroline) increases the rate, while increase in [H+] decreases the rate. Hence it can be inferred that the ...

  7. Mechanism of oxidation of L-methionine by iron(III)-1,10 ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Kinetics and mechanism of oxidation of L-methionine by iron(III)–1,10- phenanthroline complex have been studied in perchloric acid medium. The reaction is first order each in iron(III) and methionine. Increase in [phenanthroline] increases the rate while increase in [HClO4] decreases it. While the reactive species ...

  8. The effect of water on the stability of iron oxide and iron carbide nanoparticles in hydrogen and syngas followed by in situ X-ray absorption spectroscopy

    NARCIS (Netherlands)

    Thuene, P.C.; Moodley - Gengan, P.; Scheijen, F.J.E.; Fredriksson, H.O.A.; Lancee, R.J.; Kropf, J.; Miller, J.T.; Niemantsverdriet, J.W.

    2012-01-01

    The effect of water on iron-based nanoparticles under hydrogen and syngas was investigated by in situ X-ray absorption spectroscopy. The iron oxide (¿-Fe2O3) nanoparticles, dispersed as a monolayer on flat silica surfaces, were readily converted into metallic iron in dry hydrogen at 350 °C and into

  9. Iron oxides nanoparticles for heavy metals removing from industrial waters

    Energy Technology Data Exchange (ETDEWEB)

    SORA, Sergiu; Mariana, Ion Rodica [Valahia University, Targoviste (Russian Federation); Raluca, Van-Staden; Jacobus-Frederick, Van-Staden [Laboratory of Electrochemistry and PATLAB Bucharest, National Institute of Research for Electrochemistry and Condensed Matter, Bucharest (Romania)

    2011-07-01

    In the environment, the iron oxides may be useful for depollution process by means of a wide range of redox reactions. Hexavalent chromium (CrVI) is a toxic form of chromium, whereas the trivalent form is not. Reduction of CrVI to CrIII is, thus, a detoxifying process and takes place in soils and sediments under anoxic conditions. Hexavalent Cr reacts with magnetite to form CrIII. The reaction yields to a surficial transformation of magnetite into maghemite. Substitution of a large range of cations can be easily induced in magnetite and maghemite because tetrahedral as well as octahedral positions are available. Dissolution curves indicated that Co, Ni and Zn were randomly distributed within the structure and replaced octahedral Fe. In contrast, Cu, Mn and Cd appear to be concentrated near the surface of the crystals. Trace amounts of chromate ions adsorbed on magnetite are reduced to Cr (III) at the surface of Fe ions. A solid state reaction in which the surface layers of magnetite are converted into maghemite appears to be involved: as more chromate is adsorbed, further reduction is halted. Key words: magnetite nanoparticles.

  10. Mesoscopic Iron-Oxide Nanorod Polymer Nanocomposite Films

    Science.gov (United States)

    Ferrier, Robert; Ohno, Kohji; Composto, Russell

    2012-02-01

    Dispersion of nanostructures in polymer matrices is required in order to take advantage of the unique properties of the nano-sized filler. This work investigates the dispersion of mesoscopic (200 nm long) iron-oxide rods (FeNRs) grafted with poly(methyl methacrylate) (PMMA) brushes having molecular weights (MWs) of 3.7K, 32K and 160K. These rods were then dispersed in either a poly(methyl methacrylate) or poly(oxyethylene) (PEO) matrix film so that the matrix/brush interaction is either entropic (PMMA matrix) or enthalpic and entropic (PEO matrix). Transmission electron microscopy (TEM) was used to determine the dispersion of the FeNRs in the polymer matrix. The results show that the FeNRs with the largest brush were always dispersed in the matrix, whereas the rods with the shorter brushes always aggregated in the matrix. This suggests that the brush MW is a critical parameter to achieve dispersion of these mesoscopic materials. This work can be extended to understand the dispersion of other types of mesocopic particles

  11. Are iron oxide nanoparticles safe? Current knowledge and future perspectives.

    Science.gov (United States)

    Valdiglesias, Vanessa; Fernández-Bertólez, Natalia; Kiliç, Gözde; Costa, Carla; Costa, Solange; Fraga, Sonia; Bessa, Maria Joao; Pásaro, Eduardo; Teixeira, João Paulo; Laffon, Blanca

    2016-12-01

    Due to their unique physicochemical properties, including superparamagnetism, iron oxide nanoparticles (ION) have a number of interesting applications, especially in the biomedical field, that make them one of the most fascinating nanomaterials. They are used as contrast agents for magnetic resonance imaging, in targeted drug delivery, and for induced hyperthermia cancer treatments. Together with these valuable uses, concerns regarding the onset of unexpected adverse health effects following exposure have been also raised. Nevertheless, despite the numerous ION purposes being explored, currently available information on their potential toxicity is still scarce and controversial data have been reported. Although ION have traditionally been considered as biocompatible - mainly on the basis of viability tests results - influence of nanoparticle surface coating, size, or dose, and of other experimental factors such as treatment time or cell type, has been demonstrated to be important for ION in vitro toxicity manifestation. In vivo studies have shown distribution of ION to different tissues and organs, including brain after passing the blood-brain barrier; nevertheless results from acute toxicity, genotoxicity, immunotoxicity, neurotoxicity and reproductive toxicity investigations in different animal models do not provide a clear overview on ION safety yet, and epidemiological studies are almost inexistent. Much work has still to be done to fully understand how these nanomaterials interact with cellular systems and what, if any, potential adverse health consequences can derive from ION exposure. Copyright © 2016 Elsevier GmbH. All rights reserved.

  12. Transformation of iron oxides on PI electrospun membranes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Penggang; Lv, Fengzhu, E-mail: lfz619@cugb.edu.cn; Liu, Leipeng; Ding, Ling; Zhang, Yihe, E-mail: zyh@cugb.edu.cn

    2016-09-15

    Iron oxides/PI fiber membranes, especially magnetic PI membranes, are important flexible porous materials available application in the field of wave absorption, magnetic recording, membrane separation and catalysts. Therefore, α-Fe{sub 2}O{sub 3} loaded PI composite fibers were prepared by electrospinning of poly(amic acid) PAA solution followed by loading Fe{sup 3+} on the PAA membrane by ion-exchange and then imidization. Then the α-Fe{sub 2}O{sub 3} on PI membrane were reduced by H{sub 2} to give magnetic PI membranes. The content of α-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} on PI can be controlled by adjustment the ion-exchange time. The saturation magnetization of the composite membranes can reach up to 4 emu/g and the final composite membranes have magnetic response ability. - Highlights: • The content of α-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} on PI can be controlled. • The saturation magnetization of the composite membranes can reach up to 4 emu/g. • The composite membranes have magnetic response ability.

  13. Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI) Role

    KAUST Repository

    Mozo, Sergio Lentijo

    2017-01-12

    Controlled synthesis of anisotropic iron oxide nanoparticles is a challenge in the field of nanomaterial research that requires an extreme attention to detail. In particular, following up a previous work showcasing the synthesis of magnetite nanorods (NRs) using a two-step approach that made use of polyethylenenemine (PEI) as a capping ligand to synthesize intermediate β-FeOOH NRs, we studied the effect and influence of the capping ligand on the formation of β-FeOOH NRs. By comparing the results reported in the literature with those we obtained from syntheses performed (1) in the absence of PEI or (2) by using PEIs with different molecular weight, we showed how the choice of different PEIs determines the aspect ratio and the structural stability of the β-FeOOH NRs and how this affects the final products. For this purpose, a combination of XRD, HRTEM, and direct current superconducting quantum interference device (DC SQUID) magnetometry was used to identify the phases formed in the final products and study their morphostructural features and related magnetic behavior.

  14. Electron impact ionisation cross sections of iron oxides

    Science.gov (United States)

    Huber, Stefan E.; Mauracher, Andreas; Sukuba, Ivan; Urban, Jan; Maihom, Thana; Probst, Michael

    2017-12-01

    We report electron impact ionisation cross sections (EICSs) of iron oxide molecules, FexOx and FexOx+1 with x = 1, 2, 3, from the ionisation threshold to 10 keV, obtained with the Deutsch-Märk (DM) and binary-encounter-Bethe (BEB) methods. The maxima of the EICSs range from 3.10 to 9 . 96 × 10-16 cm2 located at 59-72 eV and 5.06 to 14.32 × 10-16 cm2 located at 85-108 eV for the DM and BEB approaches, respectively. The orbital and kinetic energies required for the BEB method are obtained by employing effective core potentials for the inner core electrons in the quantum chemical calculations. The BEB cross sections are 1.4-1.7 times larger than the DM cross sections which can be related to the decreasing population of the Fe 4s orbitals upon addition of oxygen atoms, together with the different methodological foundations of the two methods. Both the DM and BEB cross sections can be fitted excellently to a simple analytical expression used in modelling and simulation codes employed in the framework of nuclear fusion research. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80308-2.

  15. Oxidation influence on crystallisation in iron-based amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gloriant, T.; Surinach, S.; Munoz, J.S.; Baro, M.D. [Universitat Autonoma de Barcelona (Spain). Dept. de Fisica; Inoue, A. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    2001-07-01

    The partially crystalline iron-based nanophase composites elaborated by rapid solidification techniques are very attractive for their excellent soft magnetic properties and their potential for industrial applications. In these nanocomposite materials a control of both the structure (size, shape and distribution of the nanoparticles in the amorphous matrix) and the kinetic behaviour (nucleation and growth mechanism) is essential in order to obtain the best properties and to be able to produce them at the industrial scale. Our group has been working in this research area for a long time and the investigation presented here is the result of an international collaboration. This study deals with the effect of cobalt addition in Fe-Nb-B melt-spun amorphous alloys on the devitrification/crystallisation processes induced by thermal treatments and characterised by X-ray diffraction analysis (XRD), thermomagnetic analysis (TMG) and transmission electron microscopy observations (TEM). The transformation sequences, from the initial amorphous phase to the fully crystallised final state, were carried out using different annealing experiments (under vacuum and in air) and have revealed a strong influence of the environmental atmosphere during devitrification. It is shown that oxidation can greatly affect the crystallisation behaviour as a result of the high metastable state of the initial amorphous phase. The results and observations of this phenomenon will be presented. (orig.)

  16. Some considerations referring to mechanisms of iron oxides dissolution

    International Nuclear Information System (INIS)

    Radulescu, M.; Stefanescu, D.; Popa, L.; Mogosan, S.

    2010-01-01

    Full text: Under nuclear power plant operational conditions, the carbon steel components in a such nuclear station react with high temperature cooling agent forming several iron oxides and oxyhydroxides. These substances forming some randomly located deposits on the piping walls, can result in some damaging consequences such as: tube constrictions, pitting and intergranular corrosion and finally decreasing of heat transfer and the development of a radiation field around the primary circuit. The decontamination process being in fact a descaling process, involves the chemical dissolution of corrosion deposits in diluted acidic reagents containing usually a complexing carboxylic acid, a reductant and a corrosion inhibitor. A comparative survey of our experimental results with those published in literature on the up-mentioned topics is presented in our paper. To evaluate the removing rates of these superficial films two types of methods were used: gravimetric and potentiodynamic techniques. While the gravimetry supplied us the weight losses data necessary to establish the descaling process kinetics, the potentiodynamic method was used to compare the values of descaling rates obtained from electrochemical data. Correlating our experimental data with those from literature, we adopted two models of mechanisms applicable to our specific conditions. (authors)

  17. Iron oxide nanoparticles in modern microbiology and biotechnology.

    Science.gov (United States)

    Dinali, Ranmadugala; Ebrahiminezhad, Alireza; Manley-Harris, Merilyn; Ghasemi, Younes; Berenjian, Aydin

    2017-08-01

    Iron oxide nanoparticles (IONs) are one of the most developed and used nanomaterials in biotechnology and microbiology. These particles have unique physicochemical properties, which make them unique among nanomaterials. Therefore, many experiments have been conducted to develop facile synthesis methods for these particles and to make them biocompatible. Various effects of IONs on microorganisms have been reported. Depending on the microbial strain and nanoparticle (NP) concentration, IONs can stimulate or inhibit microbial growth. Due to the superparamagnetic properties of IONs, these NPs have used as nano sources of heat for hyperthermia in infected tissues. Antibiotic-loaded IONs are used for targeted delivery of chemical therapy direct to the infected organ and IONs have been used as a dirigible carrier for more potent antimicrobial nanomaterials such as silver nanoparticles. Magnetic NPs have been used for specific separation of pathogen and non-pathogen bacterial strains. Very recently, IONs were used as a novel tool for magnetic immobilization of microbial cells and process intensification in a biotechnological process. This review provides an overview of application of IONs in different microbial processes. Recommendations are also given for areas of future research.

  18. Sea-urchin-like iron oxide nanostructures for water treatment

    International Nuclear Information System (INIS)

    Lee, Hyun Uk; Lee, Soon Chang; Lee, Young-Chul; Vrtnik, Stane; Kim, Changsoo; Lee, SangGap; Lee, Young Boo; Nam, Bora; Lee, Jae Won; Park, So Young; Lee, Sang Moon; Lee, Jouhahn

    2013-01-01

    Highlights: • The u-MFN were synthesized via a ultrasound irradiation and/or calcinations process. • The u-MFN exhibited excellent adsorption capacities. • The u-MFN also displayed excellent adsorption of organic polluent after recycling. • The u-MFN has the potential to be used as an efficient adsorbent material. -- Abstract: To obtain adsorbents with high capacities for removing heavy metals and organic pollutants capable of quick magnetic separation, we fabricated unique sea-urchin-like magnetic iron oxide (mixed γ-Fe 2 O 3 /Fe 3 O 4 phase) nanostructures (called u-MFN) with large surface areas (94.1 m 2 g −1 ) and strong magnetic properties (57.9 emu g −1 ) using a simple growth process and investigated their potential applications in water treatment. The u-MFN had excellent removal capabilities for the heavy metals As(V) (39.6 mg g −1 ) and Cr(VI) (35.0 mg g −1 ) and the organic pollutant Congo red (109.2 mg g −1 ). The u-MFN also displays excellent adsorption of Congo red after recycling. Because of its high adsorption capacity, fast adsorption rate, and quick magnetic separation from treated water, the u-MFN developed in the present study is expected to be an efficient magnetic adsorbent for heavy metals and organic pollutants in aqueous solutions

  19. Iron Oxide Nanoparticle-Based Magnetic Ink Development for Fully Printed Tunable Radio-Frequency Devices

    KAUST Repository

    Vaseem, Mohammad; Ghaffar, Farhan A.; Farooqui, Muhammad Fahad; Shamim, Atif

    2018-01-01

    . Functionalized iron oxide nanoparticles are successfully embedded in the SU8 matrix to make a magnetic substrate. The as-fabricated substrate is characterized for its magnetostatic and microwave properties. A frequency tunable printed patch antenna

  20. Relation of iron stores to oxidative stress in type 2 diabetes | Kundu ...

    African Journals Online (AJOL)

    Relation of iron stores to oxidative stress in type 2 diabetes. ... patients who attended the outpatient and inpatient departments of Medical College, Kolkata. ... levels to MDA levels in the diabetic cases of longer duration of more than 10 years.

  1. Iron oxides in acid mine drainage environments and their association with bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Ferris, F G; Tazaki, K; Fyfe, W S

    1989-01-20

    A variety of iron oxides were identified by X-ray diffraction in sediments receiving acid drainage from mine tailing and coal refuse impoundments. Small amounts of goethite and hematite were found in the sediment samples. However, the major iron oxide species was ferrihydrite which gave diffuse diffraction bands at angles corresponding to d2.5, 2.2 and 1.5 Angstrom. Main core line binding energies in Fe (2p) and O (1s) X-ray photoelectron spectra were consistent with the hydrous nature and predominance of ferrihydrite. Electron microscopy and energy-dispersive X-ray spectroscopy also showed that individual bacterial cells promoted the development of iron oxide mineralization. The bacterial associated iron oxides were similar to those in the bulk sediment samples, and exhibited structures conforming to the presence of chemisorbed sulfate or silicate anions. 23 refs., 3 figs.

  2. Effects of oxygen gas pressure on properties of iron oxide films grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Guo, Qixin; Shi, Wangzhou; Liu, Feng; Arita, Makoto; Ikoma, Yoshifumi; Saito, Katsuhiko; Tanaka, Tooru; Nishio, Mitsuhiro

    2013-01-01

    Highlights: ► Pulsed laser deposition is a promising technique for growing iron oxide films. ► Crystal structure of the iron oxide films strongly depends on oxygen gas pressure. ► Optimum of the oxygen gas pressure leads single phase magnetite films with high crystal quality. -- Abstract: Iron oxide films were grown on sapphire substrates by pulsed laser deposition at oxygen gas pressures between 1 × 10 −5 and 1 × 10 −1 Pa with a substrate temperature of 600 °C. Atomic force microscope, X-ray diffraction, Raman spectroscopy, X-ray absorption fine structure, and vibrational sample magnetometer analysis revealed that surface morphology and crystal structure of the iron oxide films strongly depend on the oxygen gas pressure during the growth and the optimum oxygen gas pressure range is very narrow around 1 × 10 −3 Pa for obtaining single phase magnetite films with high crystal quality

  3. Colloidosome-based synthesis of a multifunctional nanostructure of silver and hollow iron oxide nanoparticles

    KAUST Repository

    Pan, Yue

    2010-03-16

    Nanoparticles that self-assemble on a liquid-liquid interface serve as the building block for making heterodimeric nanostructures. Specifically, hollow iron oxide nanoparticles within hexane form colloidosomes in the aqueous solution of silver nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray spectrometry, X-ray diffraction, UV-vis spectroscopy, and SQUID were used to characterize the heterodimers. Interestingly, the formation of silver nanoparticles helps the removal of spinglass layer on the hollow iron oxide nanoparticles. This work demonstrates a powerful yet convenient strategy for producing sophisticated, multifunctional nanostructures. © 2010 American Chemical Society.

  4. Ultrafast electron and energy transfer in dye-sensitized iron oxide and oxyhydroxide nanoparticles

    DEFF Research Database (Denmark)

    Gilbert, Benjamin; Katz, Jordan E.; Huse, Nils

    2013-01-01

    photo-initiated interfacial electron transfer. This approach enables time-resolved study of the fate and mobility of electrons within the solid phase. However, complete analysis of the ultrafast processes following dye photoexcitation of the sensitized iron(iii) oxide nanoparticles has not been reported....... We addressed this topic by performing femtosecond transient absorption (TA) measurements of aqueous suspensions of uncoated and DCF-sensitized iron oxide and oxyhydroxide nanoparticles, and an aqueous iron(iii)–dye complex. Following light absorption, excited state relaxation times of the dye of 115...... a four-state model of the dye-sensitized system, finding electron and energy transfer to occur on the same ultrafast timescale. The interfacial electron transfer rates for iron oxides are very close to those previously reported for DCF-sensitized titanium dioxide (for which dye–oxide energy transfer...

  5. Interaction of aromatic amines with iron oxides: implications for prebiotic chemistry.

    Science.gov (United States)

    Shanker, Uma; Singh, Gurinder; Kamaluddin

    2013-06-01

    The interaction of aromatic amines (aniline, p-chloroaniline, p-toludine and p-anisidine) with iron oxides (goethite, akaganeite and hematite) has been studied. Maximum uptake of amines was observed around pH 7. The adsorption data obtained at neutral pH were found to follow Langmuir adsorption. Anisidine was found to be a better adsorbate probably due to its higher basicity. In alkaline medium (pH > 8), amines reacted on goethite and akaganeite to give colored products. Analysis of the products by GC-MS showed benzoquinone and azobenzene as the reaction products of aniline while p-anisidine afforded a dimer. IR analysis of the amine-iron oxide hydroxide adduct suggests that the surface acidity of iron oxide hydroxides is responsible for the interaction. The present study suggests that iron oxide hydroxides might have played a role in the stabilization of organic molecules through their surface activity and in prebiotic condensation reactions.

  6. Eco-Friendly Magnetic Iron Oxide Pillared Montmorillonite for Advanced Catalytic Degradation of Dichlorophenol

    Science.gov (United States)

    Eco-friendly pillared montmorillonites, in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties that are applicable for environmental decontamination. Completely “green” and effective composite was synthesized using mild reactio...

  7. Formation of biomineral iron oxides compounds in a Fe hyperaccumulator plant: Imperata cylindrica (L.) P. Beauv.

    Science.gov (United States)

    Fuente, V; Rufo, L; Juárez, B H; Menéndez, N; García-Hernández, M; Salas-Colera, E; Espinosa, A

    2016-01-01

    We report a detailed work of composition and location of naturally formed iron biominerals in plant cells tissues grown in iron rich environments as Imperata cylindrica. This perennial grass grows on the Tinto River banks (Iberian Pyritic Belt) in an extreme acidic ecosystem (pH∼2.3) with high concentration of dissolved iron, sulphate and heavy metals. Iron biominerals were found at the cellular level in tissues of root, stem and leaf both in collected and laboratory-cultivated plants. Iron accumulated in this plant as a mix of iron compounds (mainly as jarosite, ferrihydrite, hematite and spinel phases) was characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Mössbauer spectroscopy (MS), magnetometry (SQUID), electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX; TEM-EDX; HRSTEM). A low fraction of phosphorous was detected in this iron hyperaccumulator plant. Root and rhizomes tissues present a high proportion of ferromagnetic iron oxide compounds. Iron oxides-rich zones are localized in electron dense intra and inter-cellular aggregates that appear as dark deposits covering the inner membrane and organelles of the cell. This study aims to contribute to a better understanding of the mechanisms of accumulation, transport, distribution of iron in Imperata cylindrica. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Oxidative dissolution of spent fuel and release of nuclides from a copper/iron canister. Model developments and applications

    Energy Technology Data Exchange (ETDEWEB)

    Longcheng Liu

    2001-12-01

    Three models have been developed and applied in the performance assessment of a final repository. They are based on accepted theories and experimental results for known and possible mechanisms that may dominate in the oxidative dissolution of spent fuel and the release of nuclides from a canister. Assuming that the canister is breached at an early stage after disposal, the three models describe three sub-systems in the near field of the repository, in which the governing processes and mechanisms are quite different. In the model for the oxidative dissolution of the fuel matrix, a set of kinetic descriptions is provided that describes the oxidative dissolution of the fuel matrix and the release of the embedded nuclides. In particular, the effect of autocatalytic reduction of hexavalent uranium by dissolved H{sub 2}, using UO{sub 2} (s) on the fuel pellets as a catalyst, is taken into account. The simulation results suggest that most of the radiolytic oxidants will be consumed by the oxidation of the fuel matrix, and that much less will be depleted by dissolved ferrous iron. Most of the radiolytically produced hexavalent uranium will be reduced by the autocatalytic reaction with H{sub 2} on the fuel surface. It will reprecipitate as UO{sub 2} (s) on the fuel surface, and thus very little net oxidation of the fuel will take place. In the reactive transport model, the interactions of multiple processes within a defective canister are described, in which numerous redox reactions take place as multiple species diffuse. The effect of corrosion of the cast iron insert of the canister and the reduction of dissolved hexavalent uranium by ferrous iron sorbed onto iron corrosion products and by dissolved H{sub 2} are particularly included. Scoping calculations suggest that corrosion of the iron insert will occur primarily under anaerobic conditions. The escaping oxidants from the fuel rods will migrate toward the iron insert. Much of these oxidants will, however, be consumed

  9. Ameliorating role of rutin on oxidative stress induced by iron overload in hepatic tissue of rats.

    Science.gov (United States)

    Aziza, Samy Ali Hussein; Azab, Mohammed El-Said; El-Shall, Soheir Kamal

    2014-08-01

    Iron is an essential element that participates in several metabolic activities of cells; however, excess iron is a major cause of iron-induced oxidative stress and several human diseases. Natural flavonoids, as rutin, are well-known antioxidants and could be efficient protective agents. Therefore, the present study was undertaken to evaluate the protective influence of rutin supplementation to improve rat antioxidant systems against IOL-induced hepatic oxidative stress. Sixty male albino rats were randomly divided to three equal groups. The first group, the control, the second group, iron overload group, the third group was used as iron overload+rutin group. Rats received six doses of ferric hydroxide polymaltose (100 mg kg(-1) b.wt.) as one dose every two days, by intraperitoneal injections (IP) and administrated rutin (50 mg kg(-1) b.wt.) as one daily oral dose until the sacrificed day. Blood samples for serum separation and liver tissue specimens were collected three times, after three, four and five weeks from the onset of the experiment. Serum iron profiles total iron, Total Iron Binding Capacity (TIBC), Unsaturated Iron Binding Capacity (UIBC), transferrin (Tf) and Transferrin Saturation% (TS%)}, ferritin, albumin, total Protein, total cholesterol, triacylglycerols levels and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were determined. Moreover, total iron in the liver, L-malondialdehyde (L-MDA), glutathione (GSH), Nitric Oxide (NO) and Total Nucleic Acid (TNA) levels and glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) activities were also determined. The obtained results revealed that, iron overload (IOL) resulted in significant increase in serum iron, TIBC, Tf, TS% and ferritin levels and AST and ALT activities and also increased liver iron, L-MDA and NO levels. Meanwhile, it decreased serum UIBC, total cholesterol, triacylglycerols, albumin, total protein and liver GSH, TNA levels and Gpx, CAT

  10. Redox?Reversible Iron Orthovanadate Cathode for Solid Oxide Steam Electrolyzer

    OpenAIRE

    Gan, Lizhen; Ye, Lingting; Ruan, Cong; Chen, Shigang; Xie, Kui

    2015-01-01

    A redox?reversible iron orthovanadate cathode is demonstrated for a solid oxide electrolyser with up to 100% current efficiency for steam electrolysis. The iron catalyst is grown on spinel?type electronic conductor FeV2O4 by in situ tailoring the reversible phase change of FeVO4 to Fe+FeV2O4 in a reducing atmosphere. Promising electrode performances have been obtained for a solid oxide steam electrolyser based on this composite cathode.

  11. Ferrous Iron Oxidation by Thiobacillus ferrooxidans: Inhibition with Benzoic Acid, Sorbic Acid, and Sodium Lauryl Sulfate

    OpenAIRE

    Onysko, Steven J.; Kleinmann, Robert L. P.; Erickson, Patricia M.

    1984-01-01

    Benzoic acid, sorbic acid, and sodium lauryl sulfate at low concentrations (5 to 10 mg/liter) each effectively inhibited bacterial oxidation of ferrous iron in batch cultures of Thiobacillus ferrooxidans. The rate of chemical oxidation of ferrous iron in low-pH, sterile batch reactors was not substantially affected at the tested concentrations (5 to 50 mg/liter) of any of the compounds.

  12. Ferrous Iron Oxidation by Thiobacillus ferrooxidans: Inhibition with Benzoic Acid, Sorbic Acid, and Sodium Lauryl Sulfate

    Science.gov (United States)

    Onysko, Steven J.; Kleinmann, Robert L. P.; Erickson, Patricia M.

    1984-01-01

    Benzoic acid, sorbic acid, and sodium lauryl sulfate at low concentrations (5 to 10 mg/liter) each effectively inhibited bacterial oxidation of ferrous iron in batch cultures of Thiobacillus ferrooxidans. The rate of chemical oxidation of ferrous iron in low-pH, sterile batch reactors was not substantially affected at the tested concentrations (5 to 50 mg/liter) of any of the compounds. PMID:16346592

  13. Zonulin, inflammation and iron status in patients with early stages of chronic kidney disease.

    Science.gov (United States)

    Lukaszyk, Ewelina; Lukaszyk, Mateusz; Koc-Zorawska, Ewa; Bodzenta-Lukaszyk, Anna; Malyszko, Jolanta

    2018-01-01

    Zonulin is the only known regulator of intestinal permeability. It is also considered as a potential inflammatory marker in several conditions such as diabetes and inflammatory bowel syndrome. The aim of the study was to investigate zonulin levels in patients with early stages of CKD and its possible correlation with inflammation, anemia and iron status parameters. Eighty-eight patients with early stages of CKD and 23 healthy volunteers were enrolled in the study. Zonulin, hepcidin-25, soluble transferrin receptor, interleukin-6 and high-sensitivity C-reactive protein were measured using commercially available assays. Zonulin was significantly lower among patients with CKD in comparison with healthy volunteers. There were no statistically significant differences in zonulin concentration between patients with and without inflammation. Zonulin was significantly correlated with hepcidin only in patients with inflammation. Zonulin was neither related to iron nor related to ferritin. Zonulin cannot be considered as an inflammatory marker in CKD. It does not play a role in the disturbances of iron metabolism in CKD. Its physiological role remains to be elucidated.

  14. Effects of manganese oxide and sulphate on the olefin selectivity of iron catalysts in the Fischer Tropsch reaction

    NARCIS (Netherlands)

    Dijk, van W.L.; Niemantsverdriet, J.W.; Kraan, van der A.M.; van der Baan, Hessel

    1982-01-01

    Although it has been claimed by various authors that the addition of manganese oxide, MnO, to an iron catalyst gives a marked increase in the olefin selectivity of iron catalysts, we have been unable to confirm these claims in Fischer Tropsch experiments at 513 K for an iron manganese oxide catalyst

  15. Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

    KAUST Repository

    Lin, Aigu L.; Rodrigues, J. N B; Su, Chenliang; Milletari, M.; Loh, Kian Ping; Wu, Tao; Chen, Wei; Neto, A. H Castro; Adam, Shaffique; Wee, Andrew T S

    2015-01-01

    Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

  16. Electrodeposition of Polypyrrole/Reduced Graphene Oxide/Iron Oxide Nanocomposite as Supercapacitor Electrode Material

    Directory of Open Access Journals (Sweden)

    Y. C. Eeu

    2013-01-01

    Full Text Available Polypyrrole (PPy was reinforced with reduced graphene oxide (RGO and iron oxide to achieve electrochemical stability and enhancement. The ternary nanocomposite film was prepared using a facile one-pot chronoamperometry approach, which is inexpensive and experimentally friendly. The field emission scanning electron microscopy (FESEM image shows a layered morphology of the ternary nanocomposite film as opposed to the dendritic structure of PPy, suggesting hybridization of the three materials during electrodeposition. X-ray diffraction (XRD profile shows the presence of Fe2O3 in the ternary nanocomposite. Cyclic voltammetry (CV analysis illustrates enhanced current for the nanocomposite by twofold and fourfold compared to its binary (PPy/RGO and individual (PPy counterparts, respectively. The ternary nanocomposite film exhibited excellent specific capacitance retention even after 200 cycles of charge/discharge.

  17. Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

    KAUST Repository

    Lin, Aigu L.

    2015-06-23

    Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

  18. 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. © 2011 American Chemical Society

  19. Persulfate activation by iron oxide-immobilized MnO2 composite: identification of iron oxide and the optimum pH for degradations.

    Science.gov (United States)

    Jo, Young-Hoon; Do, Si-Hyun; Kong, Sung-Ho

    2014-01-01

    Iron oxide-immobilized manganese oxide (MnO2) composite was prepared and the reactivity of persulfate (PS) with the composite as activator was investigated for degradation of carbon tetrachloride and benzene at various pH levels. Brunauer-Emmett-Teller (BET) surface area of the composite was similar to that of pure MnO2 while the pore volume and diameter of composite was larger than those of MnO2. Scanning electron microscopy couples with energy dispersive spectroscopy (SEM-EDS) showed that Fe and Mn were detected on the surface of the composite, and X-ray diffraction (XRD) analysis indicated the possibilities of the existence of various iron oxides on the composite surface. Furthermore, the analyses of X-ray photoelectron (XPS) spectra revealed that the oxidation state of iron was identified as 1.74. In PS/composite system, the same pH for the highest degradation rates of both carbon tetrachloride and benzene were observed and the value of pH was 9. Scavenger test was suggested that both oxidants (i.e. hydroxyl radical, sulfate radical) and reductant (i.e. superoxide anion) were effectively produced when PS was activated with the iron-immobilized MnO2. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Long-term aerobic exercise increases redox-active iron through nitric oxide in rat hippocampus.

    Science.gov (United States)

    Chen, Qian; Xiao, De-Sheng

    2014-01-30

    Adult hippocampus is highly vulnerable to iron-induced oxidative stress. Aerobic exercise has been proposed to reduce oxidative stress but the findings in the hippocampus are conflicting. This study aimed to observe the changes of redox-active iron and concomitant regulation of cellular iron homeostasis in the hippocampus by aerobic exercise, and possible regulatory effect of nitric oxide (NO). A randomized controlled study was designed in the rats with swimming exercise treatment (for 3 months) and/or an unselective inhibitor of NO synthase (NOS) (L-NAME) treatment. The results from the bleomycin-detectable iron assay showed additional redox-active iron in the hippocampus by exercise treatment. The results from nonheme iron content assay, combined with the redox-active iron content, showed increased storage iron content by exercise treatment. NOx (nitrate plus nitrite) assay showed increased NOx content by exercise treatment. The results from the Western blot assay showed decreased ferroportin expression, no changes of TfR1 and DMT1 expressions, increased IRP1 and IRP2 expression, increased expressions of eNOS and nNOS rather than iNOS. In these effects of exercise treatment, the increased redox-active iron content, storage iron content, IRP1 and IRP2 expressions were completely reversed by L-NAME treatment, and decreased ferroportin expression was in part reversed by L-NAME. L-NAME treatment completely inhibited increased NOx and both eNOS and nNOS expression in the hippocampus. Our findings suggest that aerobic exercise could increase the redox-active iron in the hippocampus, indicating an increase in the capacity to generate hydroxyl radicals through the Fenton reactions, and aerobic exercise-induced iron accumulation in the hippocampus might mainly result from the role of the endogenous NO. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Iron oxides dynamics in a subtropical Brazilian Paleudult under long-term no-tillage management

    Directory of Open Access Journals (Sweden)

    Alberto Vasconcellos Inda

    2013-02-01

    Full Text Available Replacing conventional tillage (CT with no-tillage (NT management alters the pedoenvironment and the rate of topsoil processes, with possible effects on dissolution processes associated with iron oxides and therefore soil mineralogy. This study aimed to determine the effect of NT on the content and distribution of types of iron oxides in a Rhodic Paleudult in southern Brazil. Soil samples were collected at eight depths within the 0.00-0.80 m layer under CT and NT in a long-term experiment (21 years. Mineralogical identification was conducted by X-ray diffraction (XRD, and the Fe content related to specific types of iron oxides determined by selective dissolution and diffuse-reflectance spectroscopy. Kaolinite, quartz, goethite, hematite, and maghemite were identified in the clay fraction. In the NT-managed soil, there was a decrease in the content of crystalline iron oxides and an increase in the content of poorly crystalline iron oxides with increasing proximity to the soil surface. These results suggest that iron oxides are rearranged in this soil by reductive dissolution of the crystalline types and neoformation of metastable ferrihydrite in topsoil layers, which should be assessed further in laboratory studies.

  2. Cytotoxic Effect of Iron Oxide Nanoparticles on Mouse Embryonic Stem Cells by MTT Assay

    Directory of Open Access Journals (Sweden)

    Homa Mohseni Kouchesfehani

    2016-07-01

    Full Text Available Background: Despite the wide range of applications, there is a serious lack of information on the impact of the nanoparticles on human health and the environment. The present study was done to determine the range of dangerous concentrations of iron oxide nanoparticle and their effects on mouse embryonic stem cells. Methods: Iron oxide nanoparticles with less than 20 nanometers diameter were encapsulated by a PEG-phospholipid. The suspension of iron oxide nanoparticles was prepared using the culture media and cell viability was determined by MTT assay. Results: MTT assay was used to examine the cytotoxicity of iron oxide nanoparticle s. Royan B1 cells were treated with medium containing different concentrations (10, 20, 30, 40, 50, and 60µg/ml of the iron oxide nanoparticle. Cell viability was determined at 12 and 24 hours after treatment which showed significant decreases when concentration and time period increased. Conclusion: The main mechanism of nanoparticles action is still unknown, but in vivo and in vitro studies in different environments suggest that they are capable of producing reactive oxygen species (ROS. Therefore, they may have an effect on the concentration of intracellular calcium, activation of transcription factors, and changes in cytokine. The results of this study show that the higher concentration and duration of treatment of cells with iron oxide nanoparticles increase the rate of cell death.

  3. Iron oxide deposits associated with the ectosymbiotic bacteria in the hydrothermal vent shrimp Rimicaris exoculata

    Directory of Open Access Journals (Sweden)

    P. Compère

    2008-09-01

    Full Text Available The Rimicaris exoculata shrimp is considered as a primary consumer that dominates the fauna of most Mid-Atlantic Ridge (MAR hydrothermal ecosystems. These shrimps harbour in their gill chambers an important ectosymbiotic community of chemoautotrophic bacteria associated with iron oxide deposits. The structure and elemental composition of the mineral concretions associated with these bacteria have been investigated by using LM, ESEM, TEM STEM and EDX microanalyses. The nature of the iron oxides in shrimps obtained from the Rainbow vent field has also been determined by Mössbauer spectroscopy. This multidisciplinary approach has revealed that the three layers of mineral crust in the Rimicaris exoculata shrimps consist of large concretions formed by aggregated nanoparticles of two-line ferrihydrite and include other minor elements as Si, Ca, Mg, S and P, probably present as silicates cations, sulphates or phosphates respectively that may contribute to stabilise the ferrihydrite form of iron oxides. TEM-observations on the bacteria have revealed their close interactions with these minerals. Abiotic and biotic precipitation could occur within the gill chamber of Rimicaris exoculata, suggesting the biologically-mediated formation of the iron oxide deposits. The difference of the bacterial density in the three-mineral crust layers could be correlated to the importance of the iron oxide concretions and suggest that the first mineral particles precipitates on the lower layer which could be considered as the most likely location of iron-oxidizing bacteria.

  4. The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

    International Nuclear Information System (INIS)

    Xi Dong; Luo Xiaoping; Lu Qianghua; Yao Kailun; Liu Zuli; Ning Qin

    2008-01-01

    Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method

  5. 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 ...

  6. Metal regeneration of iron chelates in nitric oxide scrubbing

    Science.gov (United States)

    Chang, S.G.; Littlejohn, D.; Shi, Y.

    1997-08-19

    The present invention relates to a process of using metal particles to reduce NO to NH{sub 3}. More specifically, the invention concerns an improved process to regenerate iron (II) (CHELATE) by reduction of iron (II) (CHELATE) (NO) complex, which process comprises: (a) contacting an aqueous solution containing iron (II) (CHELATE) (NO) with metal particles at between about 20 and 90 C to reduce NO present, produce ammonia or an ammonium ion, and produce free iron (II) (CHELATE) at a pH of between about 3 and 8. The process is useful to remove NO from flue gas and reduce pollution. 34 figs.

  7. Lactoferrin modified graphene oxide iron oxide nanocomposite for glioma-targeted drug delivery.

    Science.gov (United States)

    Song, Meng-Meng; Xu, Huai-Liang; Liang, Jun-Xing; Xiang, Hui-Hui; Liu, Rui; Shen, Yu-Xian

    2017-08-01

    Targeting delivery of drugs in a specific manner represents a potential powerful technology in gliomas. Herein, we prepared a multifunctional targeted delivery system based on graphene oxide (GO) that contains a molecular bio-targeting ligand and superparamagnetic iron oxide nanoparticles on the surface of GO for magnetic targeting. Superparamagnetic Fe 3 O 4 nanoparticles was loaded on the surface of GO via chemical precipitation method to form GO@Fe 3 O 4 nanocomposites. Lactoferrin (Lf), an iron-transporting serum glycoprotein that binds to receptors overexpressed at the surface of glioma cells and vascular endothelial cell of the blood brain barrier, was chosen as the targeted ligand to construct the targeted delivery system Lf@GO@Fe 3 O 4 through EDC/NHS chemistry. With the confirmation of TEM, DLS and VSM, the resulting Lf@GO@Fe 3 O 4 had a size distribution of 200-1000nm and exhibited a superparamagnetic behavior. The nano delivery system had a high loading capacity and exhibited a pH-dependent release behavior. Compared with free DOX and DOX@GO@Fe 3 O 4 , Lf@GO@Fe 3 O 4 @DOX displayed greater intracellular delivery efficiency and stronger cytotoxicity against C6 glioma cells. The results demonstrated the potential utility of Lf conjugated GO@Fe 3 O 4 nanocomposites for therapeutic application in the treatment of gliomas. Copyright © 2017. Published by Elsevier B.V.

  8. Mechanism of iron catalyzed oxidation of SO/sub 2/ in oxygenated solutions

    Energy Technology Data Exchange (ETDEWEB)

    Freiberg, J

    1975-01-01

    Previous experimental work concerning the iron catalyzed oxidation of SO/sub 2/ in oxygenated acid solutions failed to provide a consistent reaction mechanism and rate expression. As iron is one of the main constituents of urban atmospheric aerosols, the rate studies of heterogeneous sulphate formation in polluted city air were hampered. The present study develops a new theory for the iron catalyzed oxidation of SO/sub 2/. The resulting new rate expression is general enough to account for the results of previous experimental investigations that were performed in different ranges of SO/sub 2/ and catalyst concentrations.

  9. Iron oxide nanoparticles for use in contrast agents in magnetic resonance imaging

    International Nuclear Information System (INIS)

    Oliveira, Elisa M.N. de; Rocha, Maximiliano S. da; Caimi, Priscila de A.; Basso, Nara R. de S.; Zanini, Mara L.; Papaleo, Ricardo M.

    2015-01-01

    In this work were carried out synthesis of iron oxide nanoparticles coated with dextran, comparing the results of using different concentrations of dextran, iron salts, temperature and reaction time. The compounds were analyzed by DLS, XRD, TGA, TEM, FTIR, Zeta Potential and relaxivity. Nanoparticles with dispersion around 10-15 nm and average hydrodynamic diameters of 16-50 nm, with superparamagnetic behavior were obtained. The ratio of the relaxivities (r2/r1) in aqueous solutions was 5.30, close to value of the commercially available iron oxide contrast agents. (author)

  10. Heterogeneous biomimetic catalysis using iron porphyrin for cyclohexane oxidation promoted by chitosan

    Science.gov (United States)

    Huang, Guan; Liu, Yao; Cai, Jing Li; Chen, Xiang Feng; Zhao, Shu Kai; Guo, Yong An; Wei, Su Juan; Li, Xu

    2017-04-01

    This study investigates how ligands modulate metalloporphyrin activity with the goal of producing a practical biomimetic catalyst for use in the chemical industry. We immobilized iron porphyrinate [iron-tetrakis-(4-sulfonatophenyl)-porphyrin; Fe(III) (TPPS)] on powdered chitosan (pd-CTS) to form an immobilized catalyst Fe(III) (TPPS)/pd-CTS, which was characterized using modern spectroscopic techniques and used for catalytic oxidation of cyclohexane with O2. Amino coordination to iron porphyrin in Fe(III) (TPPS)/pd-CTS altered the electron cloud density around the iron cation, probably by reducing the activation energy of Fe(III) (TPPS) and raising the reactivity of the iron ion catalytic center, thereby improving the catalytic efficiency. One milligram of Fe(III) (TPPS) catalyst can be reused three times for the oxidation reaction to yield an average of 22.9 mol% of cyclohexanone and cyclohexanol.

  11. Labeling Efficacy of Superparamagnetic Iron Oxide Nanoparticles to Human Neural Stem Cells: Comparison of Ferumoxides, Monocrystalline Iron Oxide, Cross-linked Iron Oxide (CLIO)-NH2 and tat-CLIO

    International Nuclear Information System (INIS)

    Song, Mi Yeoun; Moon, Woo Kyung; Kim, Yun Hee; Song, In Chan; Yoon, Byung Woo; Lim, Dong Yeol

    2007-01-01

    We wanted to compare the human neural stem cell (hNSC) labeling efficacy of different superparamagnetic iron oxide nanoparticles (SPIONs), namely, ferumoxides, monocrystalline iron oxide (MION), cross-linked iron oxide (CLIO)-NH 2 and tat-CLIO. The hNSCs (5x10 5 HB1F3 cells/ml) were incubated for 24 hr in cell culture media that contained 25 μg/ml of ferumoxides, MION or CLIO-NH 2 , and with or without poly-L-lysine (PLL) and tat-CLIO. The cellular iron uptake was analyzed qualitatively with using a light microscope and this was quantified via atomic absorption spectrophotometry. The visibility of the labeled cells was assessed with MR imaging. The incorporation of SPIONs into the hNSCs did not affect the cellular proliferations and viabilities. The hNSCs labeled with tat-CLIO showed the longest retention, up to 72 hr, and they contained 2.15± 0.3 pg iron/cell, which are 59 fold, 430 fold and six fold more incorporated iron than that of the hNSCs labeled with ferumoxides, MION or CLIO-NH 2 , respectively. However, when PLL was added, the incorporation of ferumoxides, MION or CLIO-NH 2 into the hNSCs was comparable to that of tat-CLIO. For MR imaging, hNSCs can be efficiently labeled with tat-CLIO alone or with a combination of ferumoxides, MION, CLIO-NH 2 and the transfection agent PLL

  12. Labeling Efficacy of Superparamagnetic Iron Oxide Nanoparticles to Human Neural Stem Cells: Comparison of Ferumoxides, Monocrystalline Iron Oxide, Cross-linked Iron Oxide (CLIO)-NH2 and tat-CLIO

    Science.gov (United States)

    Song, Miyeoun; Kim, Yunhee; Lim, Dongyeol; Song, In-Chan; Yoon, Byung-Woo

    2007-01-01

    Objective We wanted to compare the human neural stem cell (hNSC) labeling efficacy of different superparamagnetic iron oxide nanoparticles (SPIONs), namely, ferumoxides, monocrystalline iron oxide (MION), cross-linked iron oxide (CLIO)-NH2 and tat-CLIO. Materials and Methods The hNSCs (5 × 105 HB1F3 cells/ml) were incubated for 24 hr in cell culture media that contained 25 µg/ml of ferumoxides, MION or CLIO-NH2, and with or without poly-L-lysine (PLL) and tat-CLIO. The cellular iron uptake was analyzed qualitatively with using a light microscope and this was quantified via atomic absorption spectrophotometry. The visibility of the labeled cells was assessed with MR imaging. Results The incorporation of SPIONs into the hNSCs did not affect the cellular proliferations and viabilities. The hNSCs labeled with tat-CLIO showed the longest retention, up to 72 hr, and they contained 2.15 ± 0.3 pg iron/cell, which are 59 fold, 430 fold and six fold more incorporated iron than that of the hNSCs labeled with ferumoxides, MION or CLIO-NH2, respectively. However, when PLL was added, the incorporation of ferumoxides, MION or CLIO-NH2 into the hNSCs was comparable to that of tat-CLIO. Conclusion For MR imaging, hNSCs can be efficiently labeled with tat-CLIO alone or with a combination of ferumoxides, MION, CLIO-NH2 and the transfection agent PLL. PMID:17923778

  13. Heterogeneous biomimetic catalysis using iron porphyrin for cyclohexane oxidation promoted by chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Guan, E-mail: huangg66@126.com; Liu, Yao; Cai, Jing Li; Chen, Xiang Feng; Zhao, Shu Kai; Guo, Yong An; Wei, Su Juan; Li, Xu

    2017-04-30

    Graphical abstract: A biomimetic catalyst of iron-tetrakis(4-sulfonatophenyl)porphyrin immobilized on powdered chitosan achieves efficient cyclohexane oxidation with high ketone and alcohol yields. - Highlights: • Fe (TPPS)/pd-CTS is an excellent catalyst for cyclohexane oxidation. • Amino ligation alters the electron cloud density around the iron cation. • Amino coordination likely reduces the activation energy of Fe (TPPS). • The catalyst achieved 22.9 mol% yields of cyclohexanone and cyclohexanol. - Abstract: This study investigates how ligands modulate metalloporphyrin activity with the goal of producing a practical biomimetic catalyst for use in the chemical industry. We immobilized iron porphyrinate [iron-tetrakis-(4-sulfonatophenyl)-porphyrin; Fe(III) (TPPS)] on powdered chitosan (pd-CTS) to form an immobilized catalyst Fe(III) (TPPS)/pd-CTS, which was characterized using modern spectroscopic techniques and used for catalytic oxidation of cyclohexane with O{sub 2}. Amino coordination to iron porphyrin in Fe(III) (TPPS)/pd-CTS altered the electron cloud density around the iron cation, probably by reducing the activation energy of Fe(III) (TPPS) and raising the reactivity of the iron ion catalytic center, thereby improving the catalytic efficiency. One milligram of Fe(III) (TPPS) catalyst can be reused three times for the oxidation reaction to yield an average of 22.9 mol% of cyclohexanone and cyclohexanol.

  14. Iron-tellurium-selenium mixed oxide catalysts for the selective oxidation of propylene to acrolein

    International Nuclear Information System (INIS)

    Patel, B.M.; Price, G.L.

    1990-01-01

    This paper reports on iron-tellurium-selenium mixed oxide catalysts prepared by coprecipitation from aqueous solution investigated for the propylene to acrolein reaction in the temperature range 543-773 K. Infrared spectroscopy, electron dispersive X-ray analysis, X-ray diffraction, and isotopic tracer techniques have also been employed to characterize this catalytic system. Properties of the Fe-Te-Se mixed oxide catalysts have been compared with Fe-Te mixed oxides in an effort to deduce the functionality of Se. The selenium in the Fe-Te-Se-O catalyst has been found to be the hydrocarbon activating site. The activation energies for the acrolein and carbon dioxide formation are 71 and 54 kJ/mol, respectively. Reactions carried out with 18 O 2 have shown lattice oxygen to be primarily responsible for the formation of both acrolein and carbon dioxide. The initial and rate-determining step for acrolein formation is hydrogen abstraction as determined by an isotope effect associated with the C 3 D 6 reaction. No isotope effect is observed for carbon dioxide formation from C 3 D 6 suggesting that CO 2 is formed by parallel, not consecutive, oxidation of propylene

  15. Effect of bicarbonate on iron-mediated oxidation of low-density lipoprotein

    Science.gov (United States)

    Arai, Hirofumi; Berlett, Barbara S.; Chock, P. Boon; Stadtman, Earl R.

    2005-07-01

    Oxidation of low-density lipoprotein (LDL) may play an important role in atherosclerosis. We studied the effects of bicarbonate/CO2 and phosphate buffer systems on metal ion-catalyzed oxidation of LDL to malondialdehyde (MDA) and to protein carbonyl and MetO derivatives. Our results revealed that LDL oxidation in mixtures containing free iron or heme derivatives was much greater in bicarbonate/CO2 compared with phosphate buffer. However, when copper was substituted for iron in these mixtures, the rate of LDL oxidation in both buffers was similar. Iron-catalyzed oxidation of LDL was highly sensitive to inhibition by phosphate. Presence of 0.3-0.5 mM phosphate, characteristic of human serum, led to 30-40% inhibition of LDL oxidation in bicarbonate/CO2 buffer. Iron-catalyzed oxidation of LDL to MDA in phosphate buffer was inhibited by increasing concentrations of albumin (10-200 μM), whereas MDA formation in bicarbonate/CO2 buffer was stimulated by 10-50 μM albumin but inhibited by higher concentrations. However, albumin stimulated the oxidation of LDL proteins to carbonyl derivatives at all concentrations examined in both buffers. Conversion of LDL to MDA in bicarbonate/CO2 buffer was greatly stimulated by ADP, ATP, and EDTA but only when EDTA was added at a concentration equal to that of iron. At higher than stoichiometric concentrations, EDTA prevented oxidation of LDL. Results of these studies suggest that interactions between bicarbonate and iron or heme derivatives leads to complexes with redox potentials that favor the generation of reactive oxygen species and/or to the generation of highly reactive CO2 anion or bicarbonate radical that facilitates LDL oxidation. Freely available online through the PNAS open access option.Abbreviations: LDL, low-density lipoprotein; MDA, malondialdehyde; MetO, methionine sulfoxide.

  16. Thermodynamic analysis of growth of iron oxide films by MOCVD ...

    Indian Academy of Sciences (India)

    Abstract. Thermodynamic calculations, using the criterion of minimization of total Gibbs free energy of the system, have been carried out for the metalorganic chemical vapour deposition (MOCVD) process involving the -ketoesterate complex of iron [tris(-butyl-3-oxo-butanoato)iron(III) or Fe(tbob)3] and molecular oxygen.

  17. Oxytetracycline Delivery in Adult Female Zebrafish by Iron Oxide Nanoparticles.

    Science.gov (United States)

    Chemello, Giulia; Piccinetti, Chiara; Randazzo, Basilio; Carnevali, Oliana; Maradonna, Francesca; Magro, Massimiliano; Bonaiuto, Emanuela; Vianello, Fabio; Radaelli, Giuseppe; Fifi, Anna Paola; Gigliotti, Federica; Olivotto, Ike

    2016-12-01

    Recently, the indiscriminate use of antibiotics in the aquaculture sector has raised public concern because of possible toxic effects, development of bacterial resistance, and accumulation of residues in individual tissues. Even if several countries have developed regulations about their use, it is clear that long-term growth of the aquaculture industry requires both ecologically sound practices and sustainable resource management. Alternative strategies for better management of antibiotic administration are of primary interest to improve absorption rates and, as a consequence, to reduce their release into the aquatic environment. The present study investigates, for the first time to our knowledge, a new methodology for oxytetracycline (OTC) administration through the use of iron oxide nanoparticles (NPs) (made of maghemite γ-Fe 2 O 3 ) in zebrafish (Danio rerio). Fish were divided into 4 experimental groups: control; group A exposed to 4 mg/L OTC (through water); group B exposed to the 100 mg/L SAMNs@OTC complex (equivalent to 4 mg/L OTC), and group C exposed to bare NPs. No detoxification processes or anatomical alterations were observed in fish exposed to bare NPs. Exposure of fish to the SAMNs@OTC complex resulted in a 10 times higher OTC accumulation with respect to using water exposure. This new OTC administration method seems much more efficient with respect to the traditional way of exposure and has the potentiality to reduce antibiotic utilization and possible environmental impacts. However, the dynamics related to OTC release from the SAMNs@OTC complex are still not clear and need further investigations.

  18. Sea-urchin-like iron oxide nanostructures for water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Uk, E-mail: leeho@kbsi.re.kr [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Lee, Soon Chang [Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Lee, Young-Chul [Department of Biological Engineering, College of Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Vrtnik, Stane; Kim, Changsoo; Lee, SangGap [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Lee, Young Boo; Nam, Bora [Jeonju Center, Korea Basic Science Institute, Jeonju 561-756 (Korea, Republic of); Lee, Jae Won [Department of Energy Engineering, Dankook University, Cheonan 330-714 (Korea, Republic of); Park, So Young; Lee, Sang Moon [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Lee, Jouhahn, E-mail: jouhahn@kbsi.re.kr [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of)

    2013-11-15

    Highlights: • The u-MFN were synthesized via a ultrasound irradiation and/or calcinations process. • The u-MFN exhibited excellent adsorption capacities. • The u-MFN also displayed excellent adsorption of organic polluent after recycling. • The u-MFN has the potential to be used as an efficient adsorbent material. -- Abstract: To obtain adsorbents with high capacities for removing heavy metals and organic pollutants capable of quick magnetic separation, we fabricated unique sea-urchin-like magnetic iron oxide (mixed γ-Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4} phase) nanostructures (called u-MFN) with large surface areas (94.1 m{sup 2} g{sup −1}) and strong magnetic properties (57.9 emu g{sup −1}) using a simple growth process and investigated their potential applications in water treatment. The u-MFN had excellent removal capabilities for the heavy metals As(V) (39.6 mg g{sup −1}) and Cr(VI) (35.0 mg g{sup −1}) and the organic pollutant Congo red (109.2 mg g{sup −1}). The u-MFN also displays excellent adsorption of Congo red after recycling. Because of its high adsorption capacity, fast adsorption rate, and quick magnetic separation from treated water, the u-MFN developed in the present study is expected to be an efficient magnetic adsorbent for heavy metals and organic pollutants in aqueous solutions.

  19. Recovery of iron oxides from acid mine drainage and their application as adsorbent or catalyst.

    Science.gov (United States)

    Flores, Rubia Gomes; Andersen, Silvia Layara Floriani; Maia, Leonardo Kenji Komay; José, Humberto Jorge; Moreira, Regina de Fatima Peralta Muniz

    2012-11-30

    Iron oxide particles recovered from acid mine drainage represent a potential low-cost feedstock to replace reagent-grade chemicals in the production of goethite, ferrihydrite or magnetite with relatively high purity. Also, the properties of iron oxides recovered from acid mine drainage mean that they can be exploited as catalysts and/or adsorbents to remove azo dyes from aqueous solutions. The main aim of this study was to recover iron oxides with relatively high purity from acid mine drainage to act as a catalyst in the oxidation of dye through a Fenton-like mechanism or as an adsorbent to remove dyes from an aqueous solution. Iron oxides (goethite) were recovered from acid mine drainage through a sequential precipitation method. Thermal treatment at temperatures higher than 300 °C produces hematite through a decrease in the BET area and an increase in the point of zero charge. In the absence of hydrogen peroxide, the solids adsorbed the textile dye Procion Red H-E7B according to the Langmuir model, and the maximum amount adsorbed decreased as the temperature of the thermal treatment increased. The decomposition kinetics of hydrogen peroxide is dependent on the H(2)O(2) concentration and iron oxides dosage, but the second-order rate constant normalized to the BET surface area is similar to that for different iron oxides tested in this and others studies. These results indicate that acid mine drainage could be used as a source material for the production of iron oxide catalysts/adsorbents, with comparable quality to those produced using analytical-grade reagents. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Redox switching and oxygen evolution at oxidized metal and metal oxide electrodes: iron in base.

    Science.gov (United States)

    Lyons, Michael E G; Doyle, Richard L; Brandon, Michael P

    2011-12-28

    Outstanding issues regarding the film formation, redox switching characteristics and the oxygen evolution reaction (OER) electrocatalytic behaviour of multicycled iron oxyhydroxide films in aqueous alkaline solution have been revisited. The oxide is grown using a repetitive potential multicycling technique, and the mechanism of the latter hydrous oxide formation process has been discussed. A duplex layer model of the oxide/solution interphase region is proposed. The acid/base behaviour of the hydrous oxide and the microdispersed nature of the latter material has been emphasised. The hydrous oxide is considered as a porous assembly of interlinked octahedrally coordinated anionic metal oxyhydroxide surfaquo complexes which form an open network structure. The latter contains considerable quantities of water molecules which facilitate hydroxide ion discharge at the metal site during active oxygen evolution, and also charge compensating cations. The dynamics of redox switching has been quantified via analysis of the cyclic voltammetry response as a function of potential sweep rate using the Laviron-Aoki electron hopping diffusion model by analogy with redox polymer modified electrodes. Steady state Tafel plot analysis has been used to elucidate the kinetics and mechanism of oxygen evolution. Tafel slope values of ca. 60 mV dec(-1) and ca. 120 mV dec(-1) are found at low and high overpotentials respectively, whereas the reaction order with respect to hydroxide ion activity changes from ca. 3/2 to ca. 1 as the potential is increased. These observations are rationalised in terms of a kinetic scheme involving Temkin adsorption and the rate determining formation of a physisorbed hydrogen peroxide intermediate on the oxide surface. The dual Tafel slope behaviour is ascribed to the potential dependence of the surface coverage of adsorbed intermediates.

  1. Acute iron overload and oxidative stress in brain

    International Nuclear Information System (INIS)

    Piloni, Natacha E.; Fermandez, Virginia; Videla, Luis A.; Puntarulo, Susana

    2013-01-01

    An in vivo model in rat was developed by intraperitoneally administration of Fe-dextran to study oxidative stress triggered by Fe-overload in rat brain. Total Fe levels, as well as the labile iron pool (LIP) concentration, in brain from rats subjected to Fe-overload were markedly increased over control values, 6 h after Fe administration. In this in vivo Fe overload model, the ascorbyl (A·)/ascorbate (AH − ) ratio, taken as oxidative stress index, was assessed. The A·/AH − ratio in brain was significantly higher in Fe-dextran group, in relation to values in control rats. Brain lipid peroxidation indexes, thiobarbituric acid reactive substances (TBARS) generation rate and lipid radical (LR·) content detected by Electron Paramagnetic Resonance (EPR), in Fe-dextran supplemented rats were similar to control values. However, values of nuclear factor-kappaB deoxyribonucleic acid (NFκB DNA) binding activity were significantly increased (30%) after 8 h of Fe administration, and catalase (CAT) activity was significantly enhanced (62%) 21 h after Fe administration. Significant enhancements in Fe content in cortex (2.4 fold), hippocampus (1.6 fold) and striatum (2.9 fold), were found at 6 h after Fe administration. CAT activity was significantly increased after 8 h of Fe administration in cortex, hippocampus and striatum (1.4 fold, 86, and 47%, respectively). Fe response in the whole brain seems to lead to enhanced NF-κB DNA binding activity, which may contribute to limit oxygen reactive species-dependent damage by effects on the antioxidant enzyme CAT activity. Moreover, data shown here clearly indicate that even though Fe increased in several isolated brain areas, this parameter was more drastically enhanced in striatum than in cortex and hippocampus. However, comparison among the net increase in LR· generation rate, in different brain areas, showed enhancements in cortex lipid peroxidation, without changes in striatum and hippocampus LR· generation rate after 6

  2. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    International Nuclear Information System (INIS)

    Ngoi, Kuan Hoon; Chia, Chin-Hua; Zakaria, Sarani; Chiu, Wee Siong

    2015-01-01

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature

  3. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    Energy Technology Data Exchange (ETDEWEB)

    Ngoi, Kuan Hoon; Chia, Chin-Hua, E-mail: chia@ukm.edu.my; Zakaria, Sarani [School of Applied Physics, Faculty Science and Technology, University Kebangsaan Malaysia 43600 UKM Bangi, Selangor (Malaysia); Chiu, Wee Siong [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Lembah Pantai, Kuala Lumpur (Malaysia)

    2015-09-25

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.

  4. N-butylamine functionalized graphene oxide for detection of iron(III) by photoluminescence quenching.

    Science.gov (United States)

    Gholami, Javad; Manteghian, Mehrdad; Badiei, Alireza; Ueda, Hiroshi; Javanbakht, Mehran

    2016-02-01

    An N-butylamine functionalized graphene oxide nanolayer was synthesized and characterized by ultraviolet (UV)-visible spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Detection of iron(III) based on photoluminescence spectroscopy was investigated. The N-butylamine functionalized graphene oxide was shown to specifically interact with iron (III), compared with other cationic trace elements including potassium (I), sodium (I), calcium (II), chromium (III), zinc (II), cobalt (II), copper (II), magnesium (II), manganese (II), and molybdenum (VI). The quenching effect of iron (III) on the luminescence emission of N-butylamine functionalized graphene oxide layer was used to detect iron (III). The limit of detection (2.8 × 10(-6)  M) and limit of quantitation (2.9 × 10(-5)  M) were obtained under optimal conditions. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Microbial Iron Oxidation in the Arctic Tundra and Its Implications for Biogeochemical Cycling

    Science.gov (United States)

    Scott, Jarrod J.; Benes, Joshua; Bowden, William B.

    2015-01-01

    The role that neutrophilic iron-oxidizing bacteria play in the Arctic tundra is unknown. This study surveyed chemosynthetic iron-oxidizing communities at the North Slope of Alaska near Toolik Field Station (TFS) at Toolik Lake (lat 68.63, long −149.60). Microbial iron mats were common in submerged habitats with stationary or slowly flowing water, and their greatest areal extent is in coating plant stems and sediments in wet sedge meadows. Some Fe-oxidizing bacteria (FeOB) produce easily recognized sheath or stalk morphotypes that were present and dominant in all the mats we observed. The cool water temperatures (9 to 11°C) and reduced pH (5.0 to 6.6) at all sites kinetically favor microbial iron oxidation. A microbial survey of five sites based on 16S rRNA genes found a predominance of Proteobacteria, with Betaproteobacteria and members of the family Comamonadaceae being the most prevalent operational taxonomic units (OTUs). In relative abundance, clades of lithotrophic FeOB composed 5 to 10% of the communities. OTUs related to cyanobacteria and chloroplasts accounted for 3 to 25% of the communities. Oxygen profiles showed evidence for oxygenic photosynthesis at the surface of some mats, indicating the coexistence of photosynthetic and FeOB populations. The relative abundance of OTUs belonging to putative Fe-reducing bacteria (FeRB) averaged around 11% in the sampled iron mats. Mats incubated anaerobically with 10 mM acetate rapidly initiated Fe reduction, indicating that active iron cycling is likely. The prevalence of iron mats on the tundra might impact the carbon cycle through lithoautotrophic chemosynthesis, anaerobic respiration of organic carbon coupled to iron reduction, and the suppression of methanogenesis, and it potentially influences phosphorus dynamics through the adsorption of phosphorus to iron oxides. PMID:26386054

  6. Scalable high-affinity stabilization of magnetic iron oxide nanostructures by a biocompatible antifouling homopolymer

    KAUST Repository

    Luongo, Giovanni

    2017-10-12

    Iron oxide nanostructures have been widely developed for biomedical applications, due to their magnetic properties and biocompatibility. In clinical application, the stabilization of these nanostructures against aggregation and non-specific interactions is typically achieved using weakly anchored polysaccharides, with better-defined and more strongly anchored synthetic polymers not commercially adopted due to complexity of synthesis and use. Here, we show for the first time stabilization and biocompatibilization of iron oxide nanoparticles by a synthetic homopolymer with strong surface anchoring and a history of clinical use in other applications, poly(2-methacryloyloxyethy phosphorylcholine) (poly(MPC)). For the commercially important case of spherical particles, binding of poly(MPC) to iron oxide surfaces and highly effective individualization of magnetite nanoparticles (20 nm) are demonstrated. Next-generation high-aspect ratio nanowires (both magnetite/maghemite and core-shell iron/iron oxide) are furthermore stabilized by poly(MPC)-coating, with nanowire cytotoxicity at large concentrations significantly reduced. The synthesis approach is exploited to incorporate functionality into the poly(MPC) chain is demonstrated by random copolymerization with an alkyne-containing monomer for click-chemistry. Taking these results together, poly(MPC) homopolymers and random copolymers offer a significant improvement over current iron oxide nanoformulations, combining straightforward synthesis, strong surface-anchoring and well-defined molecular weight.

  7. Scalable high-affinity stabilization of magnetic iron oxide nanostructures by a biocompatible antifouling homopolymer

    KAUST Repository

    Luongo, Giovanni; Campagnolo, Paola; Perez, Jose E.; Kosel, Jü rgen; Georgiou, Theoni K.; Regoutz, Anna; Payne, David J; Stevens, Molly M.; Ryan, Mary P.; Porter, Alexandra E; Dunlop, Iain E

    2017-01-01

    Iron oxide nanostructures have been widely developed for biomedical applications, due to their magnetic properties and biocompatibility. In clinical application, the stabilization of these nanostructures against aggregation and non-specific interactions is typically achieved using weakly anchored polysaccharides, with better-defined and more strongly anchored synthetic polymers not commercially adopted due to complexity of synthesis and use. Here, we show for the first time stabilization and biocompatibilization of iron oxide nanoparticles by a synthetic homopolymer with strong surface anchoring and a history of clinical use in other applications, poly(2-methacryloyloxyethy phosphorylcholine) (poly(MPC)). For the commercially important case of spherical particles, binding of poly(MPC) to iron oxide surfaces and highly effective individualization of magnetite nanoparticles (20 nm) are demonstrated. Next-generation high-aspect ratio nanowires (both magnetite/maghemite and core-shell iron/iron oxide) are furthermore stabilized by poly(MPC)-coating, with nanowire cytotoxicity at large concentrations significantly reduced. The synthesis approach is exploited to incorporate functionality into the poly(MPC) chain is demonstrated by random copolymerization with an alkyne-containing monomer for click-chemistry. Taking these results together, poly(MPC) homopolymers and random copolymers offer a significant improvement over current iron oxide nanoformulations, combining straightforward synthesis, strong surface-anchoring and well-defined molecular weight.

  8. Underestimation of phosphorus fraction change in the supernatant after phosphorus adsorption onto iron oxides and iron oxide-natural organic matter complexes.

    Science.gov (United States)

    Yan, Jinlong; Jiang, Tao; Yao, Ying; Wang, Jun; Cai, Yuanli; Green, Nelson W; Wei, Shiqiang

    2017-05-01

    The phosphorus (P) fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid (HA) complexes were analyzed using the ultrafiltration method in this study. With an initial P concentration of 20mg/L (I=0.01mol/L and pH=7), it was shown that the colloid (1kDa-0.45μm) component of P accounted for 10.6%, 11.6%, 6.5%, and 4.0% of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite (FH), goethite (GE), ferrihydrite-humic acid complex (FH-HA), goethite-humic acid complex (GE-HA), respectively. The oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant. And colloidal adsorbent particles co-existing in the supernatant were another important reason for it. Additionally, dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant. Ultimately, we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P, even when considering other contaminants such as organic pollutants, heavy metal ions, and arsenate at the sediment/soil-water interface in the real environment. Copyright © 2016. Published by Elsevier B.V.

  9. Water oxidation catalysis with nonheme iron complexes under acidic and basic conditions: homogeneous or heterogeneous?

    Science.gov (United States)

    Hong, Dachao; Mandal, Sukanta; Yamada, Yusuke; Lee, Yong-Min; Nam, Wonwoo; Llobet, Antoni; Fukuzumi, Shunichi

    2013-08-19

    Thermal water oxidation by cerium(IV) ammonium nitrate (CAN) was catalyzed by nonheme iron complexes, such as Fe(BQEN)(OTf)2 (1) and Fe(BQCN)(OTf)2 (2) (BQEN = N,N'-dimethyl-N,N'-bis(8-quinolyl)ethane-1,2-diamine, BQCN = N,N'-dimethyl-N,N'-bis(8-quinolyl)cyclohexanediamine, OTf = CF3SO3(-)) in a nonbuffered aqueous solution; turnover numbers of 80 ± 10 and 20 ± 5 were obtained in the O2 evolution reaction by 1 and 2, respectively. The ligand dissociation of the iron complexes was observed under acidic conditions, and the dissociated ligands were oxidized by CAN to yield CO2. We also observed that 1 was converted to an iron(IV)-oxo complex during the water oxidation in competition with the ligand oxidation. In addition, oxygen exchange between the iron(IV)-oxo complex and H2(18)O was found to occur at a much faster rate than the oxygen evolution. These results indicate that the iron complexes act as the true homogeneous catalyst for water oxidation by CAN at low pHs. In contrast, light-driven water oxidation using [Ru(bpy)3](2+) (bpy = 2,2'-bipyridine) as a photosensitizer and S2O8(2-) as a sacrificial electron acceptor was catalyzed by iron hydroxide nanoparticles derived from the iron complexes under basic conditions as the result of the ligand dissociation. In a buffer solution (initial pH 9.0) formation of the iron hydroxide nanoparticles with a size of around 100 nm at the end of the reaction was monitored by dynamic light scattering (DLS) in situ and characterized by X-ray photoelectron spectra (XPS) and transmission electron microscope (TEM) measurements. We thus conclude that the water oxidation by CAN was catalyzed by short-lived homogeneous iron complexes under acidic conditions, whereas iron hydroxide nanoparticles derived from iron complexes act as a heterogeneous catalyst in the light-driven water oxidation reaction under basic conditions.

  10. Fe2+ oxidation rate drastically affect the formation and phase of secondary iron hydroxysulfate mineral occurred in acid mine drainage

    International Nuclear Information System (INIS)

    Huang Shan; Zhou Lixiang

    2012-01-01

    During the processes of secondary iron hydroxysulfate mineral formation, Fe 2+ ion was oxidized by the following three methods: (1) biooxidation treatment by Acidithiobacillus ferrooxidans (A. ferrooxidans); (2) rapid abiotic oxidation of Fe 2+ with H 2 O 2 (rapid oxidation treatment); (3) slow abiotic oxidation of Fe 2+ with H 2 O 2 (slow oxidation treatment). X-ray diffraction (XRD) patterns, element composition, precipitate weight and total Fe removal efficiency were analyzed. The XRD patterns and element composition of precipitates synthesized through the biooxidation and the slow oxidation treatments well coincide with those of potassium jarosite, while precipitates formed at the initial stage of incubation in the rapid oxidation treatment showed a similar XRD pattern to schwertmannite. With the ongoing incubation, XRD patterns and element composition of the precipitates that occurred in the rapid oxidation treatment were gradually close to those in the biooxidation and the slow oxidation treatments. Due to the inhibition of A. ferrooxidans itself and its extracellular polymeric substances (EPS) in aggregation of precipitates, the amount of precipitates and soluble Fe removal efficiency were lower in the biooxidation treatment than in the slow oxidation treatment. Therefore, it is concluded that Fe 2+ oxidation rate can greatly affect the mineral phase of precipitates, and slow oxidation of Fe 2+ is helpful in improving jarosite formation. - Highlights: ► Slow oxidation of Fe 2+ is helpful in jarosite formation. ► The already-formed schwertmannite can be gradually transformed to jarosite. ► Precipitates formation can be inhibited probably by EPS from A. ferrooxidans.

  11. High sensitivity tracer imaging of iron oxides using magnetic particle imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goodwill, Patrick [University of California, Dept. of Bioengineering, Berkeley, CA (United States); Konkle, Justin; Lu, Kuan; Zheng, Bo [UC Berkeley (UCSF), Joint Graduate Group in Bioengineering, CA (United States); Conolly, Steven [University of California, Berkeley Bioengineering, Electrical Engineering, and Computer Science, CA (United States)

    2014-07-01

    Full text: Magnetic Particle Imaging (MPI) is a new tracer imaging modality that is gaining significant interest from NMR and MRI researchers. While the physics of MPI differ substantially from MRI, it employs hardware and imaging concepts that are familiar to MRI researchers, such as magnetic excitation and detection, pulse sequences, and relaxation effects. Furthermore, MPI employs the same superparamagnetic iron oxide (SPIO) contrast agents that are sometimes used for MR angiography and are often used for MRI cell tracking studies. These SPIOs are much safer for humans than iodine or gadolinium, especially for Chronic Kidney Disease (CKD) patients. The weak kidneys of CKD patients cannot safely excrete iodine or gadolinium, leading to increased morbidity and mortality after iodinated X-ray or CT angiograms, or after gadolinium-MRA studies. Iron oxides, on the other hand, are processed in the liver, and have been shown to be safe even for CKD patients. Unlike the 'black blood' contrast generated by SPIOs in MRI due to increased T2 dephasing, SPIOs in MPI generate positive, 'bright blood' contrast. With this ideal contrast, even prototype MPI scanners can already achieve fast, high-sensitivity, and high-contrast angiograms with millimeter-scale resolutions in phantoms and in animals. Moreover, MPI shows great potential for an exciting array of applications, including stem cell tracking in vivo, first-pass contrast studies to diagnose or stage cancer, and inflammation imaging in vivo. So far, only a handful of prototype small-animal MPI scanners have been constructed worldwide. Hence, MPI is open to great advances, especially in hardware, pulse sequence, and nanoparticle improvements, with the potential to revolutionize the biomedical imaging field. (author)

  12. High sensitivity tracer imaging of iron oxides using magnetic particle imaging

    International Nuclear Information System (INIS)

    Goodwill, Patrick; Konkle, Justin; Lu, Kuan; Zheng, Bo; Conolly, Steven

    2014-01-01

    Full text: Magnetic Particle Imaging (MPI) is a new tracer imaging modality that is gaining significant interest from NMR and MRI researchers. While the physics of MPI differ substantially from MRI, it employs hardware and imaging concepts that are familiar to MRI researchers, such as magnetic excitation and detection, pulse sequences, and relaxation effects. Furthermore, MPI employs the same superparamagnetic iron oxide (SPIO) contrast agents that are sometimes used for MR angiography and are often used for MRI cell tracking studies. These SPIOs are much safer for humans than iodine or gadolinium, especially for Chronic Kidney Disease (CKD) patients. The weak kidneys of CKD patients cannot safely excrete iodine or gadolinium, leading to increased morbidity and mortality after iodinated X-ray or CT angiograms, or after gadolinium-MRA studies. Iron oxides, on the other hand, are processed in the liver, and have been shown to be safe even for CKD patients. Unlike the 'black blood' contrast generated by SPIOs in MRI due to increased T2 dephasing, SPIOs in MPI generate positive, 'bright blood' contrast. With this ideal contrast, even prototype MPI scanners can already achieve fast, high-sensitivity, and high-contrast angiograms with millimeter-scale resolutions in phantoms and in animals. Moreover, MPI shows great potential for an exciting array of applications, including stem cell tracking in vivo, first-pass contrast studies to diagnose or stage cancer, and inflammation imaging in vivo. So far, only a handful of prototype small-animal MPI scanners have been constructed worldwide. Hence, MPI is open to great advances, especially in hardware, pulse sequence, and nanoparticle improvements, with the potential to revolutionize the biomedical imaging field. (author)

  13. Chitosan-iron oxide nanocomposite based electrochemical aptasensor for determination of malathion

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakar, Nirmal, E-mail: nirmalprabhakar@gmail.com; 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. - Highlights: • An electrochemical aptasensor for the detection of Malathion has been developed. • Chitosan-iron oxide NP deposited FTO sheets provides platform for aptamer immobilization. • Aptasensor has efficiency to detect malathion upto 0.001 ng/mL within 15 min.

  14. Beta-Thalassemia Major and Female Fertility: The Role of Iron and Iron-Induced Oxidative Stress

    Science.gov (United States)

    Roussou, Paraskevi; Tsagarakis, Nikolaos J.; Diamanti-Kandarakis, Evanthia

    2013-01-01

    Endocrine complications due to haemosiderosis are present in a significant number of patients with beta-thalassemia major (BTM) worldwide and often become barriers in their desire for parenthood. Thus, although spontaneous fertility can occur, the majority of females with BTM is infertile due to hypogonadotropic hypogonadism (HH) and need assisted reproductive techniques. Infertility in these women seems to be attributed to iron deposition and iron-induced oxidative stress (OS) in various endocrine organs, such as hypothalamus, pituitary, and female reproductive system, but also through the iron effect on other organs, such as liver and pancreas, contributing to the impaired metabolism of hormones and serum antioxidants. Nevertheless, the gonadal function of these patients is usually intact and fertility is usually retrievable. Meanwhile, a significant prooxidants/antioxidants imbalance with subsequent increased (OS) exists in patients with BTM, which is mainly caused by tissue injury due to overproduction of free radicals by secondary iron overload, but also due to alteration in serum trace elements and antioxidant enzymes. Not only using the appropriate antioxidants, essential trace elements, and minerals, but also regulating the advanced glycation end products, could probably reduce the extent of oxidative damage and related complications and retrieve BTM women's infertility. PMID:24396593

  15. Laboratory Investigation of Complex Conductivity and Magnetic Susceptibility on Natural Iron Oxide Coated Sand

    Science.gov (United States)

    Wang, C.; Slater, L. D.; Day-Lewis, F. D.; Briggs, M. A.

    2017-12-01

    Redox reactions occurring at the oxic/anoxic interface where groundwater discharges to surface water commonly result in iron oxide deposition that coats sediment grains. With relatively large total surface area, these iron oxide coated sediments serve as a sink for sorption of dissolved contaminants, although this sink may be temporary if redox conditions fluctuate with varied flow conditions. Characterization of the distribution of iron oxides in streambed sediments could provide valuable understanding of biogeochemical reactions and the ability of a natural system to sorb contaminants. Towards developing a field methodology, we conducted laboratory spectral induced polarization (SIP) and magnetic susceptibility (MS) measurements on natural iron oxide coated sand (Fe-sand) with grain sizes ranging from 0.3 to 2.0 mm in order to assess the sensitivity of these measurements to iron oxides in sediments. The Fe-sand was also sorted by sieving into various grain sizes to study the impact of grain size on the polarization mechanisms. The unsorted Fe-sand saturated with 0.01 S/m NaCl solution exhibited a distinct phase response ( > 4 mrad) in the frequency range from 0.001 to 100 Hz whereas regular silica sand was characterized by a phase response less than 1 mrad under the same conditions. The presence of iron oxide substantially increased MS (3.08×10-3 SI) over that of regular sand ( Laboratory results demonstrated that SIP and MS may be well suited to mapping the distribution of iron oxides in streambed sediments associated with anoxic groundwater discharge.

  16. DLVO and XDLVO calculations for bacteriophage MS2 adhesion to iron oxide particles.

    Science.gov (United States)

    Park, Jeong-Ann; Kim, Song-Bae

    2015-10-01

    In this study, batch experiments were performed to examine the adhesion of bacteriophage MS2 to three iron oxide particles (IOP1, IOP2 and IOP3) with different particle properties. The characteristics of MS2 and iron oxides were analyzed using various techniques to construct the classical DLVO and XDLVO potential energy profiles between MS2 and iron oxides. X-ray diffractometry peaks indicated that IOP1 was mainly composed of maghemite (γ-Fe2O3), but also contained some goethite (α-FeOOH). IOP2 was composed of hematite (α-Fe2O3) and IOP3 was composed of iron (Fe), magnetite (Fe3O4) and iron oxide (FeO). Transmission electron microscope images showed that the primary particle size of IOP1 (γ-Fe2O3) was 12.3±4.1nm. IOP2 and IOP3 had primary particle sizes of 167±35nm and 484±192nm, respectively. A surface angle analyzer demonstrated that water contact angles of IOP1, IOP2, IOP3 and MS2 were 44.83, 64.00, 34.33 and 33.00°, respectively. A vibrating sample magnetometer showed that the magnetic saturations of IOP1, IOP2 and IOP3 were 176.87, 17.02 and 946.85kA/m, respectively. Surface potentials measured in artificial ground water (AGW; 0.075mM CaCl2, 0.082mM MgCl2, 0.051mM KCl, and 1.5mM NaHCO3; pH7.6) indicated that iron oxides and MS2 were negatively charged in AGW (IOP1=-0.0185V; IOP2=-0.0194V; IOP3=-0.0301V; MS2=-0.0245V). Batch experiments demonstrated that MS2 adhesion to iron oxides was favorable in the order of IOP1>IOP2>IOP3. This tendency was well predicted by the classical DLVO model. In the DLVO calculations, both the sphere-plate and sphere-sphere geometries predicted the same trend of MS2 adhesion to iron oxides. Additionally, noticeable differences were not found between the DLVO and XDLVO interaction energy profiles, indicating that hydrophobic interactions did not play a major role; electrostatic interactions, however, did influence MS2 adhesion to iron oxides. Furthermore, the aggregation of iron oxides was investigated with a modified XDLVO

  17. Nonequilibrium iron oxide formation in some low-mass post-asymptotic giant branch stars

    Science.gov (United States)

    Rietmeijer, Frans J. M.

    1992-01-01

    Using experimental evidence that under highly oxidizing conditions gamma-Fe2O3 (maghemite) and Fe3O4 display refractory behavior, it is proposed that very low C/O ratios, that could be unique to evolving AGB stars, induce nonequilibrium formation of ferromagnetic iron oxide grains along with chondritic dust. The oxides are preferentially fractionated from chondritic dust in the stellar magnetic field which could account for the observed extreme iron underabundance in their photosphere. A search for the 1-2.5-micron IR absorption feature, or for diagnostic magnetite and maghemite IR absorption features, could show the validity of the model proposed.

  18. Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

    International Nuclear Information System (INIS)

    García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A.; Shaji, S.

    2015-01-01

    Highlights: • Laser sintered MgO pellets with nanoparticles of Al 2 O 3 and Fe 2 O 3 . • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe 2 O 3 , 20–40 nm) and aluminum oxide (Al 2 O 3 , 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm 2 with a concentration of 5 and 7 wt% of Fe 2 O 3 presented the MgFe 2 O 4 spinel-type phase. With the addition of Al 2 O 3 nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm 2 , there were the formations of MgAl 2 O 4 spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed

  19. In vitro cytotoxicity of iron oxide nanoparticles: effects of chitosan and polyvinyl alcohol as stabilizing agents

    Science.gov (United States)

    Tran, Phong A.; Nguyen, Hiep T.; Fox, Kate; Tran, Nhiem

    2018-03-01

    Iron oxide magnetic nanoparticles have significant potential in biomedical applications such as in diagnosis, imaging and therapeutic agent delivery. The choice of stabilizers and surface functionalization is important as it is known to strongly influence the cytotoxicity of the nanoparticles. The present study aimed at investigating the effects of surface charges on the cytotoxicity of iron oxide nanoparticles. We used a co-precipitation method to synthesize iron oxide nanoparticles which were then stabilized with either chitosan (CS) or polyvinyl alcohol (PVA) which have net positive charge and zero charge at physiological pH, respectively. The nanoparticles were characterized in terms of size, charges and chemical oxidation state. Cytotoxicity of the nanoparticles was assessed using mouse fibroblast cells and was correlated with surface charges of the nanoparticles and their aggregation.

  20. Iron is a signal for Stenotrophomonas maltophilia biofilm formation, oxidative stress response, OMPs expression and virulence

    Directory of Open Access Journals (Sweden)

    Carlos Adrian Garcia

    2015-09-01

    Full Text Available Stenotrophomonas maltophilia is an emerging nosocomial pathogen. In many bacteria iron availability regulates, trough the Fur system, not only iron homeostasis but also virulence. The aim of this work was to assess the role of iron on S. maltophilia biofilm formation, EPS production, oxidative stress response, OMPs regulation, quorum sensing (QS, and virulence. Studies were done on K279 and its isogenic fur mutant F60 cultured in the presence or absence of dipyridyl. This is the first report of spontaneous fur mutants obtained in S. maltophilia. F60 produced higher amounts of biofilms than K279a and CLSM analysis demonstrated improved adherence and biofilm organization. Under iron restricted conditions, K279a produced biofilms with more biomass and enhanced thickness. In addition, F60 produced higher amounts of EPS than K279a but with a similar composition, as revealed by ATR-FTIR spectroscopy. With respect to the oxidative stress response, MnSOD was the only SOD isoenzyme detected in K279a. F60 presented higher SOD activity than the wt strain in planktonic and biofilm cultures, and iron deprivation increased K279a SOD activity. Under iron starvation, SDS-PAGE profile from K279a presented two iron-repressed proteins. Mass spectrometry analysis revealed homology with FepA and another putative TonB-dependent siderophore receptor of K279a. In silico analysis allowed the detection of potential Fur boxes in the respective coding genes. K279a encodes the QS diffusible signal factor (DSF. Under iron restriction K279a produced higher amounts of DSF than under iron rich condition. Finally, F60 was more virulent than K279a in the Galleria mellonella killing assay. These results put in evidence that iron levels regulate, likely through the Fur system, S. maltophilia biofilm formation, oxidative stress response, OMPs expression, DSF production and virulence.

  1. A genetic link between magnetite mineralization and diorite intrusion at the El Romeral iron oxide-apatite deposit, northern Chile

    Science.gov (United States)

    Rojas, Paula A.; Barra, Fernando; Reich, Martin; Deditius, Artur; Simon, Adam; Uribe, Francisco; Romero, Rurik; Rojo, Mario

    2018-01-01

    El Romeral is one of the largest iron oxide-apatite (IOA) deposits in the Coastal Cordillera of northern Chile. The Cerro Principal magnetite ore body at El Romeral comprises massive magnetite intergrown with actinolite, with minor apatite, scapolite, and sulfides (pyrite ± chalcopyrite). Several generations of magnetite were identified by using a combination of optical and electron microscopy techniques. The main mineralization event is represented by zoned magnetite grains with inclusion-rich cores and inclusion-poor rims, which form the massive magnetite ore body. This main magnetite stage was followed by two late hydrothermal events that are represented by magnetite veinlets that crosscut the massive ore body and by disseminated magnetite in the andesite host rock and in the Romeral diorite. The sulfur stable isotope signature of the late hydrothermal sulfides indicates a magmatic origin for sulfur (δ34S between - 0.8 and 2.9‰), in agreement with previous δ34S data reported for other Chilean IOA and iron oxide-copper-gold deposits. New 40Ar/39Ar dating of actinolite associated with the main magnetite ore stage yielded ages of ca. 128 Ma, concordant within error with a U-Pb zircon age for the Romeral diorite (129.0 ± 0.9 Ma; mean square weighted deviation = 1.9, n = 28). The late hydrothermal magnetite-biotite mineralization is constrained at ca. 118 Ma by 40Ar/39Ar dating of secondary biotite. This potassic alteration is about 10 Ma younger than the main mineralization episode, and it may be related to post-mineralization dikes that crosscut and remobilize Fe from the main magnetite ore body. These data reveal a clear genetic association between magnetite ore formation, sulfide mineralization, and the diorite intrusion at El Romeral (at 129 Ma), followed by a late and more restricted stage of hydrothermal alteration associated with the emplacement of post-ore dikes at ca. 118 Ma. Therefore, this new evidence supports a magmatic-hydrothermal model for the

  2. Graphene oxide significantly inhibits cell growth at sublethal concentrations by causing extracellular iron deficiency.

    Science.gov (United States)

    Yu, Qilin; Zhang, Bing; Li, Jianrong; Du, Tingting; Yi, Xiao; Li, Mingchun; Chen, Wei; Alvarez, Pedro J J

    Graphene oxide (GO)-based materials are increasingly being used in medical materials and consumer products. However, their sublethal effects on biological systems are poorly understood. Here, we report that GO (at 10 to 160 mg/L) induced significant inhibitory effects on the growth of different unicellular organisms, including eukaryotes (i.e. Saccharomyces cerevisiae, Candida albicans, and Komagataella pastoris) and prokaryotes (Pseudomonas fluorescens). Growth inhibition could not be explained by commonly reported cytotoxicity mechanisms such as plasma membrane damage or oxidative stress. Based on transcriptomic analysis and measurement of extra- and intracellular iron concentrations, we show that the inhibitory effect of GO was mainly attributable to iron deficiency caused by binding to the O-functional groups of GO, which sequestered iron and disrupted iron-related physiological and metabolic processes. This inhibitory mechanism was corroborated with supplementary experiments, where adding bathophenanthroline disulfonate-an iron chelating agent-to the culture medium exerted similar inhibition, whereas removing surface O-functional groups of GO decreased iron sequestration and significantly alleviated the inhibitory effect. These findings highlight a potential indirect detrimental effect of nanomaterials (i.e. scavenging of critical nutrients), and encourage research on potential biomedical applications of GO-based materials to sequester iron and enhance treatment of iron-dependent diseases such as cancer and some pathogenic infections.

  3. Central roles of iron in the regulation of oxidative stress in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Matsuo, Ryo; Mizobuchi, Shogo; Nakashima, Maya; Miki, Kensuke; Ayusawa, Dai; Fujii, Michihiko

    2017-10-01

    Oxygen is essential for aerobic organisms but causes cytotoxicity probably through the generation of reactive oxygen species (ROS). In this study, we screened for the genes that regulate oxidative stress in the yeast Saccharomyces cerevisiae, and found that expression of CTH2/TIS11 caused an increased resistance to ROS. CTH2 is up-regulated upon iron starvation and functions to remodel metabolism to adapt to iron starvation. We showed here that increased resistance to ROS by CTH2 would likely be caused by the decreased ROS production due to the decreased activity of mitochondrial respiration, which observation is consistent with the fact that CTH2 down-regulates the mitochondrial respiratory proteins. We also found that expression of CTH1, a paralog of CTH2, also caused an increased resistance to ROS. This finding supported the above view, because mitochondrial respiratory proteins are the common targets of CTH1 and CTH2. We further showed that supplementation of iron in medium augmented the growth of S. cerevisiae under oxidative stress, and expression of CTH2 and supplementation of iron collectively enhanced its growth under oxidative stress. Since CTH2 is regulated by iron, these findings suggested that iron played crucial roles in the regulation of oxidative stress in S. cerevisiae.

  4. Iron and manganese oxide mineralization in the Pacific

    Science.gov (United States)

    Hein, J. R.; Koschinsky, A.; Halbach, P.; Manheim, F. T.; Bau, M.; Jung-Keuk, Kang; Lubick, N.

    1997-01-01

    Iron, manganese, and iron-manganese deposits occur in nearly all geomorphologic and tectonic environments in the ocean basins and form by one or more of four processes: (1) hydrogenetic precipitation from cold ambient seawater, (2) precipitation from hydrothermal fluids, (3) precipitation from sediment pore waters that have been modified from bottom water compositions by diagenetic reactions in the sediment column and (4) replacement of rocks and sediment. These processes are discussed.

  5. Ceruloplasmin Oxidation, a Feature of Parkinson's Disease CSF, Inhibits Ferroxidase Activity and Promotes Cellular Iron Retention

    KAUST Repository

    Olivieri, S.

    2011-12-14

    Parkinson\\'s disease is a neurodegenerative disorder characterized by oxidative stress and CNS iron deposition. Ceruloplasmin is an extracellular ferroxidase that regulates cellular iron loading and export, and hence protects tissues from oxidative damage. Using two-dimensional electrophoresis, we investigated ceruloplasmin patterns in the CSF of human Parkinson\\'s disease patients. Parkinson\\'s disease ceruloplasmin profiles proved more acidic than those found in healthy controls and in other human neurological diseases (peripheral neuropathies, amyotrophic lateral sclerosis, and Alzheimer\\'s disease); degrees of acidity correlated with patients\\' pathological grading. Applying an unsupervised pattern recognition procedure to the two-dimensional electrophoresis images, we identified representative pathological clusters. In vitro oxidation of CSF in two-dimensional electrophoresis generated a ceruloplasmin shift resembling that observed in Parkinson\\'s disease and co-occurred with an increase in protein carbonylation. Likewise, increased protein carbonylation was observed in Parkinson\\'s disease CSF, and the same modification was directly identified in these samples on ceruloplasmin. These results indicate that ceruloplasmin oxidation contributes to pattern modification in Parkinson\\'s disease. From the functional point of view, ceruloplasmin oxidation caused a decrease in ferroxidase activity, which in turn promotes intracellular iron retention in neuronal cell lines as well as in primary neurons, which are more sensitive to iron accumulation. Accordingly, the presence of oxidized ceruloplasmin in Parkinson\\'s disease CSF might be used as a marker for oxidative damage and might provide new insights into the underlying pathological mechanisms.

  6. Biomimetic oxidation of piperine and piplartine catalyzed by iron(III) and manganese(III) porphyrins.

    Science.gov (United States)

    Schaab, Estela Hanauer; Crotti, Antonio Eduardo Miller; Iamamoto, Yassuko; Kato, Massuo Jorge; Lotufo, Letícia Veras Costa; Lopes, Norberto Peporine

    2010-01-01

    Synthetic metalloporphyrins, in the presence of monooxygen donors, are known to mimetize various reactions of cytochrome P450 enzymes systems in the oxidation of drugs and natural products. The oxidation of piperine and piplartine by iodosylbenzene using iron(III) and manganese(III) porphyrins yielded mono- and dihydroxylated products, respectively. Piplartine showed to be a more reactive substrate towards the catalysts tested. The structures of the oxidation products were proposed based on electrospray ionization tandem mass spectrometry.

  7. Doxorubicin loaded PVA coated iron oxide nanoparticles for targeted drug delivery

    International Nuclear Information System (INIS)

    Kayal, S.; Ramanujan, R.V.

    2010-01-01

    Magnetic drug targeting is a drug delivery system that can be used in locoregional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by coprecipitation of iron oxide followed by coating with polyvinyl alcohol (PVA). Characterization was carried out using X-ray diffraction, TEM, TGA, FTIR and VSM techniques. The magnetic core of the carriers was magnetite (Fe 3 O 4 ), with average size of 10 nm. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. The amount of PVA bound to the iron oxide nanoparticles were estimated by thermogravimetric analysis (TGA) and the attachment of PVA to the iron oxide nanoparticles was confirmed by FTIR analysis. Doxorubicin (DOX) drug loading and release profiles of PVA coated iron oxide nanoparticles showed that up to 45% of adsorbed drug was released in 80 h, the drug release followed the Fickian diffusion-controlled process. The binding of DOX to the PVA was confirmed by FTIR analysis. The present findings show that DOX loaded PVA coated iron oxide nanoparticles are promising for magnetically targeted drug delivery.

  8. Adsorption of Cadmium Ions from Water on Double-walled Carbon Nanotubes/Iron Oxide Composite

    Directory of Open Access Journals (Sweden)

    Karima Seffah

    2017-12-01

    Full Text Available A new material (DWCNT/iron oxide for heavy metals removal was developed by combining the adsorption features of double-walled carbon nanotubes with the magnetic properties of iron oxides. Batch experiments were applied in order to evaluate adsorption capacity of the DWCNT/iron oxide composite for cadmium ions. The influence of operating parameters such as pH value, amount of adsorbent, initial adsorbate concentration and agitation speed was studied. The adsorption capacity of the DWCNT/iron oxide adsorbent for Cd2+ ions was 20.8 mg g-1, which is at the state of the art. The obtained results revealed that DWCNT/iron oxide composite is a very promising adsorbent for removal of Cd2+ ions from water under natural conditions. The advantage of the magnetic composite is that it can be used as adsorbent for contaminants in water and can be subsequently controlled and removed from the medium by a simple magnetic process.

  9. Magnetic and gravity gradiometry framework for Mesoproterozoic iron oxide-apatite and iron oxide-copper-gold deposits, southeast Missouri, USA

    Science.gov (United States)

    McCafferty, Anne E.; Phillips, Jeffrey; Driscoll, Rhonda L.

    2016-01-01

    High-resolution airborne magnetic and gravity gradiometry data provide the geophysical framework for evaluating the exploration potential of hidden iron oxide deposits in Mesoproterozoic basement rocks of southeast Missouri. The data are used to calculate mineral prospectivity for iron oxide-apatite (IOA) ± rare earth element (REE) and iron oxide-copper-gold (IOCG) deposits. Results delineate the geophysical footprints of all known iron oxide deposits and reveal several previously unrecognized prospective areas. The airborne data are also inverted to three-dimensional density and magnetic susceptibility models over four concealed deposits at Pea Ridge (IOA ± REE), Boss (IOCG), Kratz Spring (IOA), and Bourbon (IOCG). The Pea Ridge susceptibility model shows a magnetic source that is vertically extensive and traceable to a depth of greater than 2 km. A smaller density source, located within the shallow Precambrian basement, is partly coincident with the magnetic source at Pea Ridge. In contrast, the Boss models show a large (625-m-wide), vertically extensive, and coincident dense and magnetic stock with shallower adjacent lobes that extend more than 2,600 m across the shallow Precambrian paleosurface. The Kratz Spring deposit appears to be a smaller volume of iron oxides and is characterized by lower density and less magnetic rock compared to the other iron deposits. A prospective area identified south of the Kratz Spring deposit shows the largest volume of coincident dense and nonmagnetic rock in the subsurface, and is interpreted as prospective for a hematite-dominant lithology that extends from the top of the Precambrian to depths exceeding 2 km. The Bourbon deposit displays a large bowl-shaped volume of coincident high density and high-magnetic susceptibility rock, and a geometry that suggests the iron mineralization is vertically restricted to the upper parts of the Precambrian basement. In order to underpin the evaluation of the prospectivity and three

  10. Microwave-Assisted Combustion Synthesis of Nano Iron Oxide/Iron-Coated Activated Carbon, Anthracite, Cellulose Fiber, and Silica, with Arsenic Adsorption Studies

    Directory of Open Access Journals (Sweden)

    Mallikarjuna N. Nadagouda

    2011-01-01

    Full Text Available Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber, and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was completed within a few minutes. The method used no additional fuel and nitrate, which is present in the precursor itself, to drive the reaction. The obtained samples were then characterized with X-ray mapping, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDS, selected area diffraction pattern (SAED, transmission electron microscopy (TEM, X-ray diffraction (XRD, and inductively coupled plasma (ICP spectroscopy. The size of the iron oxide/iron nanoparticle-coated activated carbon, anthracite, cellulose fiber, and silica samples were found to be in the nano range (50–400 nm. The iron oxide/iron nanoparticles mostly crystallized into cubic symmetry which was confirmed by SAED. The XRD pattern indicated that iron oxide/iron nano particles existed in four major phases. That is, γ-Fe2O3, α-Fe2O3, Fe3O4, and Fe. These iron-coated activated carbon, anthracite, cellulose fiber, and silica samples were tested for arsenic adsorption through batch experiments, revealing that few samples had significant arsenic adsorption.

  11. Magnetic characteristics of ultrafine Fe particles reduced from uniform iron oxide particles

    Science.gov (United States)

    Bridger, K.; Watts, J.; Tadros, M.; Xiao, Gang; Liou, S. H.; Chien, C. L.

    1987-04-01

    Uniform, cubic 0.05-μm iron oxide particles were formed by forced hydrolysis of ferric perchlorate. These particles were reduced to α-Fe by heating in hydrogen at temperatures between 300 and 500 °C. The effect of reduction temperature and various prereduction treatments on the microstructure of the iron particles will be discussed. Complete reduction to α-Fe was established by 57Fe Mössbauer spectroscopy and x-ray diffraction. Magnetic measurements on epoxy and polyurethane films containing these particles with various mass fractions gave coercivities as high as 1000 Oe. The relationship between the magnetic measurements and the microstructure will be discussed. Na2SiO3 is found to be the best coating material for the process of reducing iron oxide particles to iron.

  12. Stability of oxidized iron species and the redox budget of slab-derived fluids

    Science.gov (United States)

    Sanchez-Valle, C.; Hin, R.; Testemale, D.; Borca, C.; Grolimund, D.

    2017-12-01

    The high oxidation state of subduction zone magmas compared to magmas from other locations might result from the influx of oxidized fluid from the subducted oceanic plate into the mantle wedge. However, the nature of the chemical agent(s) and the mechanism responsible for the transfer of the oxidized signature from the slab to the mantle wedge remains poorly understood. In this contribution, we will discuss the oxidizing capacity of slab-derived fluids in the light of experimental results of the solubility and speciation of iron in high-pressure fluids that mimic the slab flux. Iron-bearing mineral assemblages were equilibrated with chlorinated aqueous fluids and hydrous granitic melts at different oxygen fugacities relevant for the present day crust/mantle. The concentration of iron and the distribution of stability of oxidized iron species were monitored up to 2.5 GPa and 800 °C using a combination of diamond trap experiments and XANES measurements in diamond anvil cells. The results illustrate the role of coordination chemistry involving halogen and polymerized species in the stability of oxidized iron in the fluids. The concentration of Fe3+ in the fluids progressively decreases as temperature increases, regardless of fluid composition and pressure. This implies that the fluid capacity to transport Fe3+ at high temperature may be limited, even at the redox conditions relevant for the present day crust and mantle. With the new experimental results, we place constrains on the oxidizing capacity of Fe-bearing metasomatic fluids and discuss the transfer of the oxidizing signature and the conditions for the genesis of oxidized arc magmas.

  13. 'NC100150', a preparation of iron oxide nanoparticles ideal for positive-contrast MR angiography.

    Science.gov (United States)

    Kellar, K E; Fujii, D K; Gunther, W H; Briley-Saebø, K; Spiller, M; Koenig, S H

    1999-08-01

    A laboratory-scale synthesis of NC100150 (iron oxide particles with an oxidized starch coating) was characterized by magnetization measurements (vibrating sample magnetometry, VSM), relaxometry (1/T1 NMRD profiles and 1/T2 at 10 and 20 MHz), and dynamic light scattering (photon correlation spectroscopy, PCS). The results were related to give a self-consistent physical description of the particles: a water-impenetrable part making up 12% of the total particle volume, 82% of this volume consisting of an iron oxide core and the remaining 18% consisting of an oxidized starch rind; and, a water-penetrable part making up 88% of the total particle volume, consisting of oxidized starch polymers and entrained water molecules. Relating the magnetization to the relaxometry results required that the oxidized starch coating slows the diffusivity of solvent water molecules in the vicinity of the iron oxide cores. The effect of the organic coating on water diffusivity, not previously considered in the application of relaxation theory to iron oxide nanoparticles, is supported by the much greater (factor of about 2) diameter obtained from the dynamic light scattering measurements in comparison to that obtained from the magnetization measurements. The present work shows that three physical techniques--VSM, relaxometry, and PCS--are needed for properly assessing iron oxide nanoparticles for use as contrast agents for magnetic resonance angiography (MRA). It is also shown that NC100150 has a narrow range of diameters and the smallest value of r2/r1 reported to date, an asset for MRA.

  14. Scalable fractionation of iron oxide nanoparticles using a CO2 gas-expanded liquid system

    International Nuclear Information System (INIS)

    Vengsarkar, Pranav S.; Xu, Rui; Roberts, Christopher B.

    2015-01-01

    Iron oxide nanoparticles exhibit highly size-dependent physicochemical properties that are important in applications such as catalysis and environmental remediation. In order for these size-dependent properties to be effectively harnessed for industrial applications scalable and cost-effective techniques for size-controlled synthesis or size separation must be developed. The synthesis of monodisperse iron oxide nanoparticles can be a prohibitively expensive process on a large scale. An alternative involves the use of inexpensive synthesis procedures followed by a size-selective processing technique. While there are many techniques available to fractionate nanoparticles, many of the techniques are unable to efficiently fractionate iron oxide nanoparticles in a scalable and inexpensive manner. A scalable apparatus capable of fractionating large quantities of iron oxide nanoparticles into distinct fractions of different sizes and size distributions has been developed. Polydisperse iron oxide nanoparticles (2–20 nm) coated with oleic acid used in this study were synthesized using a simple and inexpensive version of the popular coprecipitation technique. This apparatus uses hexane as a CO 2 gas-expanded liquid to controllably precipitate nanoparticles inside a 1L high-pressure reactor. This paper demonstrates the operation of this new apparatus and for the first time shows the successful fractionation results on a system of metal oxide nanoparticles, with initial nanoparticle concentrations in the gram-scale. The analysis of the obtained fractions was performed using transmission electron microscopy and dynamic light scattering. The use of this simple apparatus provides a pathway to separate large quantities of iron oxide nanoparticles based upon their size for use in various industrial applications.

  15. Non-equilibrium oxidation states of zirconium during early stages of metal oxidation

    International Nuclear Information System (INIS)

    Ma, Wen; Yildiz, Bilge; Herbert, F. William; Senanayake, Sanjaya D.

    2015-01-01

    The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr 1+ , Zr 2+ , and Zr 3+ as non-equilibrium oxidation states, in addition to Zr 4+ in the stoichiometric ZrO 2 . This finding resolves the long-debated question of whether it is possible to form any valence states between Zr 0 and Zr 4+ at the metal-oxide interface. The presence of local strong electric fields and the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr

  16. Solvent free oxidation of primary alcohols and diols using thymine iron(III) catalyst.

    Science.gov (United States)

    Al-Hunaiti, Afnan; Niemi, Teemu; Sibaouih, Ahlam; Pihko, Petri; Leskelä, Markku; Repo, Timo

    2010-12-28

    In this study, we developed an efficient and selective iron-based catalyst system for the synthesis of ketones from secondary alcohols and carboxylic acids from primary alcohol. In situ generated iron catalyst of thymine-1-acetate (THA) and FeCl(3) under solvent-free condition exhibits high activity. As an example, 1-octanol and 2-octanol were oxidized to 1-octanoic acid and 2-octanone with 89% and 98% yields respectively.

  17. Iron oxide nanoparticles for plant nutrition? A preliminary Mössbauer study

    Energy Technology Data Exchange (ETDEWEB)

    Homonnay, Z., E-mail: homonnay@caesar.elte.hu [EötvösLoránd University, Institute of Chemistry (Hungary); Tolnai, Gy. [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry (Hungary); Fodor, F.; Solti, Á. [EötvösLoránd University, Institute of Biology (Hungary); Kovács, K.; Kuzmann, E.; Ábrahám, A. [EötvösLoránd University, Institute of Chemistry (Hungary); Szabó, E. Gy.; Németh, P.; Szabó, L.; Klencsár, Z. [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry (Hungary)

    2016-12-15

    One of the most important micronutrients for plants is iron. We have prepared iron(III) oxyhydroxide and magnetite nanoparticles with the aim to use them as possible nutrition source for plants. The iron(III)-oxide/oxyhydroxide nanoparticles prepared under our experimental conditions as colloidal suspensions proved to be 6-line ferrihydrite nanoparticles as verified by XRD, TEM/SAED and Mössbauer spectroscopy measurements. {sup 57}Fe Mössbauer spectra of magnetite nanoparticles prepared under different preparation conditions could be analyzed on the basis of a common model based on the superposition of four sextet components displaying Gaussian-shaped hyperfine magnetic field distributions.

  18. Galvanic Corrosion of Lead by Iron (Oxyhydr)Oxides: Potential Impacts on Drinking Water Quality.

    Science.gov (United States)

    Trueman, Benjamin F; Sweet, Gregory A; Harding, Matthew D; Estabrook, Hayden; Bishop, D Paul; Gagnon, Graham A

    2017-06-20

    Lead exposure via drinking water remains a significant public health risk; this study explored the potential effects of upstream iron corrosion on lead mobility in water distribution systems. Specifically, galvanic corrosion of lead by iron (oxyhydr)oxides was investigated. Coupling an iron mineral cathode with metallic lead in a galvanic cell increased lead release by 531 μg L -1 on average-a 9-fold increase over uniform corrosion in the absence of iron. Cathodes were composed of spark plasma sintered Fe 3 O 4 or α-Fe 2 O 3 or field-extracted Fe 3 O 4 and α-FeOOH. Orthophosphate immobilized oxidized lead as insoluble hydroxypyromorphite, while humic acid enhanced lead mobility. Addition of a humic isolate increased lead release due to uniform corrosion by 81 μg L -1 and-upon coupling lead to a mineral cathode-release due to galvanic corrosion by 990 μg L -1 . Elevated lead in the presence of humic acid appeared to be driven by complexation, with 208 Pb and UV 254 size-exclusion chromatograms exhibiting strong correlation under these conditions (R 2 average = 0.87). A significant iron corrosion effect was consistent with field data: lead levels after lead service line replacement were greater by factors of 2.3-4.7 at sites supplied by unlined cast iron distribution mains compared with the alternative, lined ductile iron.

  19. Solid-state Water-mediated Transport Reduction of Nanostructured Iron Oxides

    International Nuclear Information System (INIS)

    Smirnov, Vladimir M.; Povarov, Vladimir G.; Voronkov, Gennadii P.; Semenov, Valentin G.; Murin, Igor' V.; Gittsovich, Viktor N.; Sinel'nikov, Boris M.

    2001-01-01

    The Fe 2+ /Fe 3+ ratio in two-dimensional iron oxide nanosructures (nanolayers with a thickness of 0.3-1.5 nm on silica surface) may be precisely controlled using the transport reduction (TR) technique. The species ≡-O-Fe(OH) 2 and (≡Si-O-) 2 -FeOH forming the surface monolayer are not reduced at 400-600 deg. C because of their covalent bonding to the silica surface, as demonstrated by Moessbauer spectroscopy. Iron oxide microparticles (microstructures) obtained by the impregnation technique, being chemically unbound to silica, are subjected to reduction at T ≥ 500 deg. C with formation of metallic iron in the form of α-Fe. Transport reduction of supported nanostructures (consisting of 1 or 4 monolayers) at T ≥ 600 deg. C produces bulk iron(II) silicate and metallic iron phases. The structural-chemical transformations occurring in transport reduction of supported iron oxide nanolayers are proved to be governed by specific phase processes in the nanostructures themselves

  20. Review of the Evidence from Epidemiology, Toxicology, and Lung Bioavailability on the Carcinogenicity of Inhaled Iron Oxide Particulates.

    Science.gov (United States)

    Pease, Camilla; Rücker, Thomas; Birk, Thomas

    2016-03-21

    Since the iron-age and throughout the industrial age, humans have been exposed to iron oxides. Here, we review the evidence from epidemiology, toxicology, and lung bioavailability as to whether iron oxides are likely to act as human lung carcinogens. Current evidence suggests that observed lung tumors in rats result from a generic particle overload effect and local inflammation that is rat-specific under the dosing conditions of intratracheal instillation. This mode of action therefore, is not relevant to human exposure. However, there are emerging differences seen in vitro, in cell uptake and cell bioavailability between "bulk" iron oxides and "nano" iron oxides. "Bulk" particulates, as defined here, are those where greater than 70% are >100 nm in diameter. Similarly, "nano" iron oxides are defined in this context as particulates where the majority, usually >95% for pure engineered forms of primary particulates (not agglomerates), fall in the range 1-100 nm in diameter. From the weight of scientific evidence, "bulk" iron oxides are not genotoxic/mutagenic. Recent evidence for "nano" iron oxide is conflicting regarding genotoxic potential, albeit genotoxicity was not observed in an in vivo acute oral dose study, and "nano" iron oxides are considered safe and are being investigated for biomedical uses; there is no specific in vivo genotoxicity study on "nano" iron oxides via inhalation. Some evidence is available that suggests, hypothetically due to the larger surface area of "nano" iron oxide particulates, that toxicity could be exerted via the generation of reactive oxygen species (ROS) in the cell. However, the potential for ROS generation as a basis for explaining rodent tumorigenicity is only apparent if free iron from intracellular "nano" scale iron oxide becomes bioavailable at significant levels inside the cell. This would not be expected from "bulk" iron oxide particulates. Furthermore, human epidemiological evidence from a number of studies suggests that

  1. Towards a Mechanistic Understanding of Anaerobic Nitrate Dependent Iron Oxidation: Balancing Electron Uptake and Detoxification

    Directory of Open Access Journals (Sweden)

    Hans Karl Carlson

    2012-02-01

    Full Text Available The anaerobic oxidation of Fe(II by subsurface microorganisms is an important part of biogeochemical cycling in the environment, but the biochemical mechanisms used to couple iron oxidation to nitrate respiration are not well understood. Based on our own work and the evidence available in the literature, we propose a mechanistic model for anaerobic nitrate dependent iron oxidation. We suggest that anaerobic iron oxidizing microorganisms likely exist along a continuum including: 1 bacteria that inadvertently oxidize Fe(II by abiotic or biotic reactions with enzymes or chemical intermediates in their metabolic pathways (e.g. denitrification and suffer from toxicity or energetic penalty, 2 Fe(II tolerant bacteria that gain little or no growth benefit from iron oxidation but can manage the toxic reactions, and 3 bacteria that efficiently accept electrons from Fe(II to gain a growth advantage while preventing or mitigating the toxic reactions. Predictions of the proposed model are highlighted and experimental approaches are discussed.

  2. Oxidative stress response in neural stem cells exposed to different superparamagnetic iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Pongrac IM

    2016-04-01

    Full Text Available Igor M Pongrac,1 Ivan Pavičić,2 Mirta Milić,2 Lada Brkič Ahmed,1 Michal Babič,3 Daniel Horák,3 Ivana Vinković Vrček,2 Srećko Gajović1 1School of Medicine, Croatian Institute for Brain Research, University of Zagreb, 2Institute for Medical Research and Occupational Health, Zagreb, Croatia; 3Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic Abstract: Biocompatibility, safety, and risk assessments of superparamagnetic iron oxide nanoparticles (SPIONs are of the highest priority in researching their application in biomedicine. One improvement in the biological properties of SPIONs may be achieved by different functionalization and surface modifications. This study aims to investigate how a different surface functionalization of SPIONs – uncoated, coated with D-mannose, or coated with poly-L-lysine – affects biocompatibility. We sought to investigate murine neural stem cells (NSCs as important model system for regenerative medicine. To reveal the possible mechanism of toxicity of SPIONs on NSCs, levels of reactive oxygen species, intracellular glutathione, mitochondrial membrane potential, cell-membrane potential, DNA damage, and activities of SOD and GPx were examined. Even in cases where reactive oxygen species levels were significantly lowered in NSCs exposed to SPIONs, we found depleted intracellular glutathione levels, altered activities of SOD and GPx, hyperpolarization of the mitochondrial membrane, dissipated cell-membrane potential, and increased DNA damage, irrespective of the surface coating applied for SPION stabilization. Although surface coating should prevent the toxic effects of SPIONs, our results showed that all of the tested SPION types affected the NSCs similarly, indicating that mitochondrial homeostasis is their major cellular target. Despite the claimed biomedical benefits of SPIONs, the refined determination of their effects on various cellular functions

  3. Ex situ integration of iron oxide nanoparticles onto the exfoliated expanded graphite flakes in water suspension

    Directory of Open Access Journals (Sweden)

    Jović Nataša

    2014-01-01

    Full Text Available Hybrid structures composed of exfoliated expanded graphite (EG and iron oxide nanocrystals have been produced by an ex situ process. The iron oxide nanoparticles coated with meso-2,3-dimercaptosuccinic acid (DMSA, or poly(acrylic acid (PAA were integrated onto the exfoliated EG flakes by mixing their aqueous suspensions at room temperature under support of 1-ethyl-3-(3-dimethylaminopropylcarbodiimide (EDC and N-hydroxysuccin-nimide (NHS. EG flakes have been used both, naked and functionalized with branched polyethylenimine (PEI. Complete integration of two constituents has been achieved and mainteined stable for more than 12 months. No preferential spatial distribution of anchoring sites for attachement of iron oxide nanoparticles has been observed, regardless EG flakes have been used naked or functionalized with PEI molecules. The structural and physico-chemical characteristics of the exfoliated expanded graphite and its hybrids nanostructures has been investigated by SEM, TEM, FTIR and Raman techniques. [Projekat Ministarstva nauke Republike Srbije, br. 45015

  4. Preparation and characterization of an iron oxide-hydroxyapatite nanocomposite for potential bone cancer therapy.

    Science.gov (United States)

    Sneha, Murugesan; Sundaram, Nachiappan Meenakshi

    2015-01-01

    Recently, multifunctional magnetic nanostructures have been found to have potential applications in biomedical and tissue engineering. Iron oxide nanoparticles are biocompatible and have distinctive magnetic properties that allow their use in vivo for drug delivery and hyperthermia, and as T2 contrast agents for magnetic resonance imaging. Hydroxyapatite is used frequently due to its well-known biocompatibility, bioactivity, and lack of toxicity, so a combination of iron oxide and hydroxyapatite materials could be useful because hydroxyapatite has better bone-bonding ability. In this study, we prepared nanocomposites of iron oxide and hydroxyapatite and analyzed their physicochemical properties. The results suggest that these composites have superparamagnetic as well as biocompatible properties. This type of material architecture would be well suited for bone cancer therapy and other biomedical applications.

  5. Imaging pathobiology of carotid atherosclerosis with ultrasmall superparamagnetic particles of iron oxide: an update.

    Science.gov (United States)

    Sadat, Umar; Usman, Ammara; Gillard, Jonathan H

    2017-07-01

    To provide brief overview of the developments regarding use of ultrasmall superparamagnetic particles of iron oxide in imaging pathobiology of carotid atherosclerosis. MRI is a promising technique capable of providing morphological and functional information about atheromatous plaques. MRI using iron oxide particles, called ultrasmall superparamagnetic iron oxide (USPIO) particles, allows detection of macrophages in atherosclerotic tissue. Ferumoxytol has emerged as a new USPIO agent, which has an excellent safety profile. Based on the macrophage-selective properties of ferumoxytol, there is increasing number of recent reports suggesting its effectiveness to detect pathological inflammation. USPIO particles allow magnetic resonance detection of macrophages in atherosclerotic tissue. Ferumoxytol has emerged as a new USPIO agent, with an excellent safety profile. This has the potential to be used for MRI of the pathobiology of atherosclerosis.

  6. Iron oxide contrast media improve MR-imaging of the portal venous system -an experimental study

    International Nuclear Information System (INIS)

    Boeck, J.C.; Knollmann, F.D.; Teltenkoetter, S.; Wlodarcyk, W.; Muehler, A.; Felix, R.

    1997-01-01

    Purpose: The aim was to demonstrate that intravenous superparamagnetic iron oxide contrast agents improve the delineation of the portal venous system. Material and methods: The portal venous system of 8 minipigs was demonstrated by a FLASH 2-D MRA-sequence. Scans were acquired before and after intravenous administration of 10 and 20 μmol/kg of a superparamagnetic iron oxide contrast agent (SHU 555 A). Signal intensities were measured in the portal vein and hepatic parenchym and contrast-to-noise ratios were calculated. Results: Following a cumulative dose of 10 μmol iron oxide, hepatic parenchymal signal intensity decreased to 67±6%, following 20 μmol to 29±4%, and following 40 μmol to 13±2% of control (p [de

  7. Enhancement of aspirin capsulation by porous particles including iron hydrous oxide

    International Nuclear Information System (INIS)

    Saito, Kenji; Koishi, Masumi; Hosoi, Fumio; Makuuchi, Keizo.

    1986-01-01

    Polymer-coated porous particles containing aspirin as a drug were prepared and the release of rate of aspirin was studied. The impregnation of aspirin was carried out by post-graft polymerization, where methyl methacrylate containing aspirin was treated with porous particles including iron oxide, pre-irradiated with γ-ray form Co-60. Release of aspirin from modified particles was examined with 50 % methanol solution. The amount of aspirin absorbed in porous particles increased by grafting of methyl methacrylate. The particles treated with iron hydrous oxide sols before irradiation led to the increment of aspirin absorption. Diffusion of aspirin through the polymer matrix and the gelled layer was the limiting process in the aspirin release from particles. The rate of aspirin released from modified particles including iron hydrous oxide wasn't affected by the grafting of methyl methacrylate. (author)

  8. In situ functionalization and PEO coating of iron oxide nanocrystals using seeded emulsion polymerization.

    Science.gov (United States)

    Kloust, Hauke; Schmidtke, Christian; Feld, Artur; Schotten, Theo; Eggers, Robin; Fittschen, Ursula E A; Schulz, Florian; Pöselt, Elmar; Ostermann, Johannes; Bastús, Neus G; Weller, Horst

    2013-04-16

    Herein we demonstrate that seeded emulsion polymerization is a powerful tool to produce multiply functionalized PEO coated iron oxide nanocrystals. Advantageously, by simple addition of functional surfactants, functional monomers, or functional polymerizable linkers-solely or in combinations thereof-during the seeded emulsion polymerization process, a broad range of in situ functionalized polymer-coated iron oxide nanocrystals were obtained. This was demonstrated by purposeful modulation of the zeta potential of encapsulated iron oxide nanocrystals and conjugation of a dyestuff. Successful functionalization was unequivocally proven by TXRF. Furthermore, the spatial position of the functional groups can be controlled by choosing the appropriate spacers. In conclusion, this methodology is highly amenable for combinatorial strategies and will spur rapid expedited synthesis and purposeful optimization of a broad scope of nanocrystals.

  9. Hybrid Iron Oxide-Graphene Oxide-Polysaccharides Microcapsule: A Micro-Matryoshka for On-demand Drug Release and Antitumor Therapy In Vivo

    KAUST Repository

    Deng, Lin; Li, Qiujin; Al-Rehili, Safa'a; Omar, Haneen; Almalik, Abdulaziz; Alshamsan, Aws; Zhang, Jianfei; Khashab, Niveen M.

    2016-01-01

    microcapsule (h-MC) by a simple layer-by-layer technique comprising polysaccharides (Alg, Chi, HA), iron oxide, and graphene oxide. Electrostatic assembly of the oppositely charged polysaccharides and graphene sheets provided a robust structure to load drugs

  10. Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Henych, Jiří, E-mail: henych@iic.cas.cz [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Janoš, Pavel; Kuráň, Pavel; Štastný, Martin [Faculty of the Environment, J.E. Purkyně University, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

    2015-07-30

    Highlights: • Ti–Fe mixed oxides were synthesized via low-temperature one-pot method. • Mixed oxides were used for degradation of parathion methyl. • Pure reference oxide samples showed no degradation ability. • Mixed oxides reached 70% degree of conversion of parathion methyl. - Abstract: Titania-iron mixed oxides with various Ti:Fe ratio were prepared by homogeneous hydrolysis of aqueous solutions of titanium(IV) oxysulphate and iron(III) sulphate with urea as a precipitating agent. The synthesized samples were characterized by X-ray diffraction, Raman and infrared spectroscopy, scanning and transmission electron microscopy, XRF analysis, specific surface area (BET) and porosity determination (BJH). These oxides were used for degradation of organophosporus pesticide parathion methyl. The highest degradation efficiency approaching <70% was found for the samples with Ti:Fe ratio 0.25:1 and 1:0.25. Contrary, parathion methyl was not degraded on the surfaces of pure oxides. In general, the highest degradation rate exhibited samples consisted of the iron or titanium oxide containing a moderate amount of the admixture. However, distinct correlations between the degradation rate and the sorbent composition were not identified.

  11. Thermal and magnetic properties of iron oxide colloids: influence of surfactants

    International Nuclear Information System (INIS)

    I P Soares, Paula; Lochte, Frederik; Echeverria, Coro; M M Ferreira, Isabel; P M R Borges, João; C J Pereira, Laura; T Coutinho, Joana; M M Novo, Carlos

    2015-01-01

    Iron oxide nanoparticles (NPs) have been extensively studied in the last few decades for several biomedical applications such as magnetic resonance imaging, magnetic drug delivery and hyperthermia. Hyperthermia is a technique used for cancer treatment which consists in inducing a temperature of about 41–45 °C in cancerous cells through magnetic NPs and an external magnetic field. Chemical precipitation was used to produce iron oxide NPs 9 nm in size coated with oleic acid and trisodium citrate. The influence of both stabilizers on the heating ability and in vitro cytotoxicity of the produced iron oxide NPs was assessed. Physicochemical characterization of the samples confirmed that the used surfactants do not change the particles’ average size and that the presence of the surfactants has a strong effect on both the magnetic properties and the heating ability. The heating ability of Fe_3O_4 NPs shows a proportional increase with the increase of iron concentration, although when coated with trisodium citrate or oleic acid the heating ability decreases. Cytotoxicity assays demonstrated that both pristine and trisodium citrate Fe_3O_4 samples do not reduce cell viability. However, oleic acid Fe_3O_4 strongly reduces cell viability, more drastically in the SaOs-2 cell line. The produced iron oxide NPs are suitable for cancer hyperthermia treatment and the use of a surfactant brings great advantages concerning the dispersion of NPs, also allowing better control of the hyperthermia temperature. (paper)

  12. Interactions of benzoic acid and phosphates with iron oxide colloids using chemical force titration.

    Science.gov (United States)

    Liang, Jana; Horton, J Hugh

    2005-11-08

    Colloidal iron oxides are an important component in soil systems and in water treatment processes. Humic-based organic compounds, containing both phenol and benzoate functional groups, are often present in these systems and compete strongly with phosphate species for binding sites on the iron oxide surfaces. Here, we examine the interaction of benzoate and phenolic groups with various iron oxide colloids using atomic force microscopy (AFM) chemical force titration measurements. Self-assembled monolayers (SAMs) of 4-(12-mercaptododecyloxy)benzoic acid and 4-(12-mercaptododecyloxy)phenol were used to prepare chemically modified Au-coated AFM tips, and these were used to probe the surface chemistry of a series of iron oxide colloids. The SAMs formed were also characterized using scanning tunneling microscopy, reflection-absorption infrared spectroscopy, and X-ray photoelectron spectroscopy. The surface pK(a) of 4-(12- mercaptododecyloxy)benzoic acid has been determined to be 4.0 +/- 0.5, and the interaction between the tip and the sample coated with a SAM of this species is dominated by hydrogen bonding. The chemical force titraton profile for an AFM probe coated with 4-(12- mercaptododecyloxy)benzoic acid and a bare iron oxide colloid demonstrates that the benzoic acid function group interacts with all three types of iron oxide sites present on the colloid surface over a wide pH range. Similar experiments were carried out on colloids precipitated in the presence of phosphoric, gallic, and tannic acids. The results are discussed in the context of the competitive binding interactions of solution species present in soils or in water treatment processes.

  13. Template-assisted hydrothermally synthesized iron-titanium binary oxides and their application as catalysts for ethyl acetate oxidation

    Czech Academy of Sciences Publication Activity Database

    Tsoncheva, T.; Ivanova, R.; Dimitrov, M.; Paneva, D.; Kovacheva, D.; Henych, Jiří; Vomáčka, Petr; Kormunda, M.; Velinov, N.; Mitov, I.; Štengl, Václav

    2016-01-01

    Roč. 528, NOV (2016), s. 24-35 ISSN 0926-860X R&D Projects: GA MŠk(CZ) LM2015073 Institutional support: RVO:61388980 Keywords : Effect of Fe/Ti ratio and temperature of hydrothermal treatment * Hydrothermal synthesis * Iron-titanium binary oxides Subject RIV: CA - Inorganic Chemistry Impact factor: 4.339, year: 2016

  14. Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2015-05-01

    Highlights: • Laser sintered MgO pellets with nanoparticles of Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}. • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe{sub 2}O{sub 3}, 20–40 nm) and aluminum oxide (Al{sub 2}O{sub 3}, 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2} with a concentration of 5 and 7 wt% of Fe{sub 2}O{sub 3} presented the MgFe{sub 2}O{sub 4} spinel-type phase. With the addition of Al{sub 2}O{sub 3} nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2}, there were the formations of MgAl{sub 2}O{sub 4} spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed.

  15. Solubilization of plutonium hydrous oxide by iron-reducing bacteria

    International Nuclear Information System (INIS)

    Rusin, P.A.; Quintana, L.; Brainard, J.R.; Strietelmeler, B.A.; Tait, C.D.; Ekberg, S.A.; Palmer, P.D.; Newton, T.W.; Clark, D.L.

    1994-01-01

    The removal of plutonium from soils id challenging because of its strong sorption to soils and limited solubility, Microbial reduction of metals is known to affect the speciation and solubility of sparingly soluble metals in the environment, notably iron and manganese. The similarity in reduction potential for α-FeOOH(s) and hydrous PuO 2 (s) suggests that iron-reducing bacteria may also reduce and solubilize plutonium. Bacillus strains were used to demonstrate that iron-reducing bacteria mediate the solubilization of hydrous PuO 2 (s) under anaerobic conditions. Up to ∼90% of the PuO 2 was biosolubilized in the presence of nitrilotriacetic acid (NTA) within 6-7 days. Biosolubilization occurred to a lesser extent (∼ 40%) in the absence of NTA. Little PuO 2 solubilization occurred in sterile culture media or in the presence of a non-iron-reducing Escherichia coli. These observations suggest a potentially attractive, environmentally benign strategy for the remediation of Pu-contaminated soils. 26 refs., 5 figs., 2 tabs

  16. ARSENIC MOBILITY FROM IRON OXIDE SOLIDS PRODUCED DURING WATER TREATMENT

    Science.gov (United States)

    The Arsenic Rule under the Safe Drinking Water Act will require certain drinking water suppliers to add to or modify their existing treatment in order to comply with the new 10 ppb arsenic standard. One of the treatment options is co-precipitation of arsenic with iron. This tre...

  17. Sonochemically synthesized iron-doped zinc oxide nanoparticles: Influence of precursor composition on characteristics

    International Nuclear Information System (INIS)

    Roy, Anirban; Maitra, Saikat; Ghosh, Sobhan; Chakrabarti, Sampa

    2016-01-01

    Highlights: • Sonochemical synthesis of iron-doped zinc oxide nanoparticles. • Green synthesis without alkali at room temperature. • Characterization by UV–vis spectroscopy, FESEM, XRD and EDX. • Influence of precursor composition on characteristics. • Composition and characteristics are correlated. - Abstract: Iron-doped zinc oxide nanoparticles have been synthesized sonochemically from aqueous acetyl acetonate precursors of different proportions. Synthesized nanoparticles were characterized with UV–vis spectroscopy, X-ray diffraction and microscopy. Influences of precursor mixture on the characteristics have been examined and modeled. Linear correlations have been proposed between dopant dosing, extent of doping and band gap energy. Experimental data corroborated with the proposed models.

  18. Electron small polarons and their mobility in iron (oxyhydr)oxide nanoparticles

    DEFF Research Database (Denmark)

    Katz, Jordan E; Zhang, Xiaoyi; Attenkofer, Klaus

    2012-01-01

    Electron mobility within iron (oxyhydr)oxides enables charge transfer between widely separated surface sites. There is increasing evidence that this internal conduction influences the rates of interfacial reactions and the outcomes of redox-driven phase transformations of environmental interest....... To determine the links between crystal structure and charge-transport efficiency, we used pump-probe spectroscopy to study the dynamics of electrons introduced into iron(III) (oxyhydr)oxide nanoparticles via ultrafast interfacial electron transfer. Using time-resolved x-ray spectroscopy and ab initio...

  19. Selectivity and Activity of Iron Molybdate Catalysts in Oxidation of Methanol

    OpenAIRE

    Khalid Khazzal Hummadi; Karim H. Hassan; Phillip C.H. Mitchell

    2009-01-01

    The selectivity and activity of iron molybdate catalysts prepared by different methods are compared with those of a commercial catalyst in the oxidation of methanol to formaldehyde in a continuous tubular bed reactor at 200-350 oC (473-623 oK), 10 atm (1013 kPa), with a methanol-oxygen mixture fixed at 5.5% by volume methanol: air ratio. The iron(III) molybdate catalyst prepared by co-precipitation and filtration had a selectivity towards formaldehyde in methanol oxidation comparable with a c...

  20. Electrochemical reduction of nitroaromatic compounds by single sheet iron oxide coated electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Li-Zhi, E-mail: lizhi@plen.ku.dk [Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK–1871 Frederiksberg C (Denmark); Hansen, Hans Christian B. [Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK–1871 Frederiksberg C (Denmark); Bjerrum, Morten Jannik [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK–2100 København Ø (Denmark)

    2016-04-05

    Highlights: • Composite layers of single sheet iron oxides were coated on indium tin oxide electrodes. • Single sheet iron oxide is an electro-catalyst for reduction of nitroaromatic compounds in aqueous solution. • The reduction is well explained by a diffusion layer model. • The charge properties of the nitrophenols have an important influence on reduction. • Low-cost iron oxide based materials are promising electro-catalyst for water treatment. - Abstract: Nitroaromatic compounds are substantial hazard to the environment and to the supply of clean drinking water. We report here the successful reduction of nitroaromatic compounds by use of iron oxide coated electrodes, and demonstrate that single sheet iron oxides formed from layered iron(II)-iron(III) hydroxides have unusual electrocatalytic reactivity. Electrodes were produced by coating of single sheet iron oxides on indium tin oxide electrodes. A reduction current density of 10 to 30 μA cm{sup −2} was observed in stirred aqueous solution at pH 7 with concentrations of 25 to 400 μM of the nitroaromatic compound at a potential of −0.7 V vs. SHE. Fast mass transfer favors the initial reduction of the nitroaromatic compound which is well explained by a diffusion layer model. Reduction was found to comprise two consecutive reactions: a fast four-electron first-order reduction of the nitro-group to the hydroxylamine-intermediate (rate constant = 0.28 h{sup −1}) followed by a slower two-electron zero-order reduction resulting in the final amino product (rate constant = 6.9 μM h{sup −1}). The zero-order of the latter reduction was attributed to saturation of the electrode surface with hydroxylamine-intermediates which have a more negative half-wave potential than the parent compound. For reduction of nitroaromatic compounds, the SSI electrode is found superior to metal electrodes due to low cost and high stability, and superior to carbon-based electrodes in terms of high coulombic efficiency and

  1. A microbial-mineralization approach for syntheses of iron oxides with a high specific surface area.

    Science.gov (United States)

    Yagita, Naoki; Oaki, Yuya; Imai, Hiroaki

    2013-04-02

    Of minerals and microbes: A microbial-mineralization-inspired approach was used to facilitate the syntheses of iron oxides with a high specific surface area, such as 253 m(2)g(-1) for maghemite (γ-Fe(2)O(3)) and 148 m(2)g(-1) for hematite (α-Fe(2)O(3)). These iron oxides can be applied to electrode material of lithium-ion batteries, adsorbents, and catalysts. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Microwave-assisted combustion synthesis of nano iron oxide/iron-coated activated carbon, anthracite, cellulose fiber, and silica, with arsenic adsorption studies

    Science.gov (United States)

    Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was com...

  3. Microbial iron mats at the Mid-Atlantic Ridge and evidence that Zetaproteobacteria may be restricted to iron-oxidizing marine systems.

    Directory of Open Access Journals (Sweden)

    Jarrod J Scott

    Full Text Available Chemolithoautotrophic iron-oxidizing bacteria play an essential role in the global iron cycle. Thus far, the majority of marine iron-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine iron-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of iron-oxidizing communities at hydrothermal systems along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent systems on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit using the ROV Jason II. The goal of these efforts was to determine if iron-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high iron(II concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial iron mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of iron-oxyhydroxide structures, indicating that active iron-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these iron mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other iron-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an iron source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests

  4. Fossilization of Iron-Oxidizing Bacteria at Hydrothermal Vents: a Useful Biosignature on Mars?

    Science.gov (United States)

    Leveille, R. J.; Lui, S.

    2009-05-01

    Iron oxidizing bacteria are ubiquitous in marine and terrestrial environments on Earth, where they often display distinctive cell morphologies and are commonly encrusted by minerals, especially bacteriogenic iron oxides and silica. Putative microfossils of iron oxidizing bacteria have been found in jaspers as old as 490Ma and microbial iron oxidation may be an ancient metabolic pathway. In order to investigate the usefulness of mineralized iron oxidizing bacteria as a biosignature, we have examined mineral samples collected from relict hydrothermal systems along Explorer Ridge, NE Pacific Ocean. In addition, microaerophilic, neutrophilic iron oxidizing bacteria, isolated from Pacific hydrothermal vents, were grown in a Fe-enriched seawater medium at constant pH (6.5) and oxygen concentration (5 percent) in a controlled bioreactor system. Both natural samples and experimental products were examined with a combination of variable pressure scanning electron microscopy (SEM), field emission gun SEM, and in some cases by preparing samples with a focused ion beam (FIB) milling system. Natural seafloor samples display abundant filamentous forms often resembling, in both size and shape, the twisted stalks of Gallionella and the elongated filaments of Leptothrix. Generally, these filamentous features are 1-5 microns in diameter and up to several microns in length. Some samples consist entirely of low- density, porous masses of silica encrusted filamentous forms. Presumably, these masses were formed by a rapid precipitation by the influx of silica-rich fluids into a microbial mat dominated by bacteria with filamentous morphologies. The presence of rare, amorphous (unmineralized) filamentous matter rich in C and Fe suggests that these bacteria were iron oxidizers. There is no evidence that sulfur oxidizers were present. Filamentous features sectioned by FIB milling show internal material within semi-hollow tubular-like features. Silica encrustations also show pseudo

  5. Oxidative stability of a heme iron-fortified bakery product: Effectiveness of ascorbyl palmitate and co-spray-drying of heme iron with calcium caseinate.

    Science.gov (United States)

    Alemán, Mercedes; Bou, Ricard; Tres, Alba; Polo, Javier; Codony, Rafael; Guardiola, Francesc

    2016-04-01

    Fortification of food products with iron is a common strategy to prevent or overcome iron deficiency. However, any form of iron is a pro-oxidant and its addition will cause off-flavours and reduce a product's shelf life. A highly bioavailable heme iron ingredient was selected to fortify a chocolate cream used to fill sandwich-type cookies. Two different strategies were assessed for avoiding the heme iron catalytic effect on lipid oxidation: ascorbyl palmitate addition and co-spray-drying of heme iron with calcium caseinate. Oxidation development and sensory acceptability were monitored in the cookies over one-year of storage at room temperature in the dark. The addition of ascorbyl palmitate provided protection against oxidation and loss of tocopherols and tocotrienols during the preparation of cookies. In general, ascorbyl palmitate, either alone or in combination with the co-spray-dried heme iron, prevented primary oxidation and hexanal formation during storage. The combination of both strategies resulted in cookies that were acceptable from a sensory point of view after 1year of storage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Lymphocyte DNA damage and oxidative stress in patients with iron deficiency anemia.

    Science.gov (United States)

    Aslan, Mehmet; Horoz, Mehmet; Kocyigit, Abdurrahim; Ozgonül, Saadet; Celik, Hakim; Celik, Metin; Erel, Ozcan

    2006-10-10

    Oxidant stress has been shown to play an important role in the pathogenesis of iron deficiency anemia. The aim of this study was to investigate the association between lymphocyte DNA damage, total antioxidant capacity and the degree of anemia in patients with iron deficiency anemia. Twenty-two female with iron deficiency anemia and 22 healthy females were enrolled in the study. Peripheral DNA damage was assessed using alkaline comet assay and plasma total antioxidant capacity was determined using an automated measurement method. Lymphocyte DNA damage of patients with iron deficiency anemia was significantly higher than controls (ptotal antioxidant capacity was significantly lower (ptotal antioxidant capacity and hemoglobin levels (r=0.706, ptotal antioxidant capacity and hemoglobin levels were negatively correlated with DNA damage (r=-0.330, p<0.05 and r=-0.323, p<0.05, respectively). In conclusion, both oxidative stress and DNA damage are increased in IDA patients. Increased oxidative stress seems as an important factor that inducing DNA damage in those IDA patients. The relationships of oxidative stress and DNA damage with the severity of anemia suggest that both oxidative stress and DNA damage may, in part, have a role in the pathogenesis of IDA.

  7. Thermodynamic Characterization of Iron Oxide-Aqueous Fe(2+) Redox Couples.

    Science.gov (United States)

    Gorski, Christopher A; Edwards, Rebecca; Sander, Michael; Hofstetter, Thomas B; Stewart, Sydney M

    2016-08-16

    Iron is present in virtually all terrestrial and aquatic environments, where it participates in redox reactions with surrounding metals, organic compounds, contaminants, and microorganisms. The rates and extent of these redox reactions strongly depend on the speciation of the Fe2+ and Fe3+ phases, although the underlying reasons remain unclear. In particular, numerous studies have observed that Fe2+ associated with iron oxide surfaces (i.e., oxide-associated Fe2+) often reduces oxidized contaminants much faster than aqueous Fe2+ alone. Here, we tested two hypotheses related to this observation by determining if solutions containing two commonly studied iron oxides—hematite and goethite—and aqueous Fe2+ reached thermodynamic equilibrium over the course of a day. We measured reduction potential (EH) values in solutions containing these oxides at different pH values and aqueous Fe2+ concentrations using mediated potentiometry. This analysis yielded standard reduction potential (EH0) values of 768 ± 1 mV for the aqueous Fe2+–goethite redox couple and 769 ± 2 mV for the aqueous Fe2+–hematite redox couple. These values were in excellent agreement with those calculated from existing thermodynamic data, and the data could be explained by the presence of an iron oxide lowering EH values of aqueous Fe3+/Fe2+ redox couples.

  8. Destructive behavior of iron oxide in projectile impact

    Science.gov (United States)

    Shang, Wang; Xiaochen, Wang; Quan, Yang; Zhongde, Shan

    2017-12-01

    The damage strain values of Q235-A surface oxide scale were obtained by scanning electron microscopy (SEM/EDS) and universal tensile testing machine. The finite element simulation was carried out to study the destruction effects of oxidation at different impact rates. The results show that the damage value of the oxide strain is 0.08%. With the increase of the projectile velocity, the damage area of the oxide scale is increased, and the damage area is composed of the direct destruction area and the indirect failure area. The indirect damage area is caused by the stress/strain to the surrounding expansion after the impact of the steel body.

  9. Electronic properties of thermally formed thin iron oxide films

    International Nuclear Information System (INIS)

    Wielant, J.; Goossens, V.; Hausbrand, R.; Terryn, H.

    2007-01-01

    The oxide layer, present between an organic coating and the substrate, guarantees adhesion of the coating and plays a determinating role in the delamination rate of the organic coating. The purpose of this study is to compare the resistive and semiconducting properties of thermal oxides formed on steel in two different atmospheres at 250 deg. C: an oxygen rich atmosphere, air, and an oxygen deficient atmosphere, N 2 . In N 2 , a magnetite layer grows while in air a duplex oxide film forms composed by an inner magnetite layer and a thin outer hematite scale. The heat treatment for different amounts of time at high temperature was used as method to sample the thickness variation and change in electronic and semiconducting properties of the thermal oxide layers. Firstly, linear voltammetric measurements were performed to have a first insight in the electrochemical behavior of the thermal oxides in a borate buffer solution. Electrochemical impedance spectroscopy in the same buffer combined with the Mott-Schottky analysis were used to determine the semiconducting properties of the thermal oxides. By spectroscopic ellipsometry (SE) and atomic force microscopy (AFM), respectively, the thickness and roughness of the oxide layers were determined supporting the physical interpretation of the voltammetric and EIS data. These measurements clearly showed that oxide layers with different constitution, oxide resistance, flatband potential and doping concentration can be grown by changing the atmosphere

  10. Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Wael Ahmed Abou Taleb Sayed

    2011-01-13

    This work presents the experimental results of the synthesis of unsupported and supported SiC iron oxide nanoparticles and their catalytic activity towards ethanol partial oxidation. For comparison, further unsupported iron oxide phases were investigated towards the ethanol partial oxidation. These {gamma}-Fe{sub 2}O{sub 3} and {alpha}/{gamma}-Fe{sub 2}O{sub 3} phase catalysts were prepared by the CVS method using Fe(CO){sub 5} as precursor, supplied by another author. The {alpha}-Fe{sub 2}O{sub 3} and SiC nanoparticles were prepared by the CVS method using a home made hot wall reactor technique at atmospheric pressure. Ferrocene and tetramethylsilane were used as precursor for the production process. Process parameters of precursor evaporation temperature, precursor concentration, gas mixture velocity and gas mixture dilution were investigated and optimised to produce particle sizes in a range of 10 nm. For Fe{sub 2}O{sub 3}/SiC catalyst series production, a new hot wall reactor setup was used. The particles were produced by simultaneous thermal decomposition of ferrocene and tetramethylsilane in one reactor from both sides. The production parameters of inlet tube distance inside the reactor, precursor evaporation temperature and carrier gas flow were investigated to produce a series of samples with different iron oxide content. The prepared catalysts composition, physical and chemical properties were characterized by XRD, EDX, SEM, BET surface area, FTIR, XPS and dynamic light scattering (DLS) techniques. The catalytic activity for the ethanol gas-phase oxidation was investigated in a temperature range from 260 C to 290 C. The product distributions obtained over all catalysts were analysed with mass spectrometry analysis tool. The activity of bulk Fe{sub 2}O{sub 3} and SiC nanoparticles was compared with prepared nano-iron oxide phase catalysts. The reaction parameters, such as reaction temperature and O{sub 2}/ethanol ratio were investigated. The catalysts

  11. Kinetic studies on the oxidation of oxyhemoglobin by biologically active iron thiosemicarbazone complexes: relevance to iron-chelator-induced methemoglobinemia.

    Science.gov (United States)

    Basha, Maram T; Rodríguez, Carlos; Richardson, Des R; Martínez, Manuel; Bernhardt, Paul V

    2014-03-01

    The oxidation of oxyhemoglobin to methemoglobin has been found to be facilitated by low molecular weight iron(III) thiosemicarbazone complexes. This deleterious reaction, which produces hemoglobin protein units unable to bind dioxygen and occurs during the administration of iron chelators such as the well-known 3-aminopyridine-2-pyridinecarbaldehyde thiosemicarbazone (3-AP; Triapine), has been observed in the reaction with Fe(III) complexes of some members of the 3-AP structurally-related thiosemicarbazone ligands derived from di-2-pyridyl ketone (HDpxxT series). We have studied the kinetics of this oxidation reaction in vitro using human hemoglobin and found that the reaction proceeds with two distinct time-resolved steps. These have been associated with sequential oxidation of the two different oxyheme cofactors in the α and β protein chains. Unexpected steric and hydrogen-bonding effects on the Fe(III) complexes appear to be the responsible for the observed differences in the reaction rate across the series of HDpxxT ligand complexes used in this study.

  12. Bacterial Oxidation and Reduction of Iron in the Processes of Creation and Treatment of Acid Mining Waters

    Directory of Open Access Journals (Sweden)

    Daniel Kupka

    2004-12-01

    Full Text Available Acid mine drainages (AMDs arise at the weathering of sulphidic minerals. The occurrence of acidic streams is commonly associated with the human mining activities. Due to the disruption and excavation of sulphide deposits, the oxidation processes have initiated. Acidic products of sulphide oxidation accelerate the degradation of accompanying minerals. AMDs typically contain high concentrations of sulfuric acid and soluble metals and cause serious ecological problems due to the water pollution and the devastation of adjacent country. Microbial life in these extremely acidic environments may be considerably diverse. AMDs are abundant in bacteria capable to oxidize and/or to reduce iron. The rate of bacterial oxidation of ferrous iron released from pyrite surfaces is up to one million times faster than the chemical oxidation rate at low pH. Bacterial regeneration of ferric iron maintains the continuity of pyrite oxidation and the production of AMDs. Another group of microorganisms living in these environments are acidophilic ferric iron reducing bacteria. This group of microorganisms has been discovered only relatively recently. Acidophilic heterotrophic bacteria reduce ferric iron in either soluble or solid forms to ferrous iron. The reductive dissolution of ferric iron minerals brings about a mobilization of iron as well as associated heavy metals. The Bacterial oxidation and reduction of iron play an important role in the transformation of either crystalline or amorphous iron-containing minerals, including sulphides, oxides, hydroxysulfates, carbonates and silicates. This work discusses the role of acidophilic bacteria in the natural iron cycling and the genesis of acidic effluents. The possibilities of application of iron bacteria in the remediation of AMDs are also considered.

  13. Iron Overload Is Associated With Oxidative Stress and Nutritional Immunity During Viral Infection in Fish.

    Science.gov (United States)

    Tarifeño-Saldivia, Estefanía; Aguilar, Andrea; Contreras, David; Mercado, Luis; Morales-Lange, Byron; Márquez, Katherine; Henríquez, Adolfo; Riquelme-Vidal, Camila; Boltana, Sebastian

    2018-01-01

    Iron is a trace element, essential to support life due to its inherent ability to exchange electrons with a variety of molecules. The use of iron as a cofactor in basic metabolic pathways is essential to both pathogenic microorganisms and their hosts. During evolution, the shared requirement of micro- and macro-organisms for this important nutrient has shaped the pathogen-host relationship. Infectious pancreatic necrosis virus (IPNv) affects salmonids constituting a sanitary problem for this industry as it has an important impact on post-smolt survival. While immune modulation induced by IPNv infection has been widely characterized on Salmo salar , viral impact on iron host metabolism has not yet been elucidated. In the present work, we evaluate short-term effect of IPNv on several infected tissues from Salmo salar . We observed that IPNv displayed high tropism to headkidney, which directly correlates with a rise in oxidative stress and antiviral responses. Transcriptional profiling on headkidney showed a massive modulation of gene expression, from which biological pathways involved with iron metabolism were remarkable. Our findings suggest that IPNv infection increase oxidative stress on headkidney as a consequence of iron overload induced by a massive upregulation of genes involved in iron metabolism.

  14. Sulfate Adsorption on Iron Nanocomposites on Graphene Oxide and Activated Carbon Beds

    Directory of Open Access Journals (Sweden)

    Rezvan Birooni

    2017-01-01

    Full Text Available This study is an experimental investigation of sulfate removal efficiency using iron nanocomposites on graphene oxide and activated carbon beds. The graphene oxide used was synthesized according to the Hummer method during which process graphene oxide and activated carbon were added. The effects of various parameters including adsorbent content, pH, and contact time on adsorption were investigated. Furthermore, the data were subjected to kinetic studies. Results revealed that the highest absorption rates of 84% and 62% were achieved for iron on the graphene oxide and activated carbon beds, respectively, when 0.06 g of the adsorbent was used at pH =11 over a contact time of 9 hours. It was also found that the kinetic pseudo-second-order model best fit the data. Finally, the results indicated that the two environmentally-friendly adsorbents have a good potential for removing sulfate from aqueous solutions.

  15. Iron carbide on titania surface modified with group VA oxides as Fischer-Tropsch catalysts

    International Nuclear Information System (INIS)

    Wachs, I.E.; Fiato, R.A.; Chersich, C.C.

    1986-01-01

    A catalyst is described comprising iron carbide supported on a surface modified titania wherein the support comprises an oxide of a metal selected form the group consisting of niobium, vanadium, tantalum or mixture thereof supported on the titania wherein at least a portion of the supported oxide of niobium, vanandium, tantalum or mixture is in a non-crystalline form. The amount of the supported oxide ranges from about 0.5 to 25 weight percent metal oxide on the titania support based on the total support composition and the catalyst contains at least about 2 milligrams of iron, calculated as Fe/sub 2/O/sub 3/, per square meter of support surface

  16. Highly efficient Cu-decorated iron oxide nanocatalyst for low pressure CO 2 conversion

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Avik; Kilianová, Martina; Yang, Bing; Tyo, Eric C.; Seifert, Soenke; Prucek, Robert; Panáček, Aleš; Suchomel, Petr; Tomanec, Ondřej; Gosztola, David J.; Milde, David; Wang, Hsien-Hau; Kvítek, Libor; Zbořil, Radek; Vajda, Stefan

    2018-06-01

    We report a nanoparticulate iron oxide based catalyst for CO2 conversion with high efficiency at low pressures and on the effect of the presence of copper on the catalyst's restructuring and its catalytic performance. In situ X-ray scattering reveals the restructuring of the catalyst at the nanometer scale. In situ X-ray absorption near edge structure (XANES) shows the evolution of the composition and oxidation state of the iron and copper components under reaction conditions along with the promotional effect of copper on the chemical transformation of the iron component. X-ray diffraction (XRD), XANES and Raman spectroscopy proved that the starting nano catalyst is composed of iron oxides differing in chemical nature (alpha-Fe2O3, Fe3O4, FeO(OH)) and dimensionality, while the catalyst after CO2 conversion was identified as a mixture of alpha-Fe, Fe3C, and traces of Fe5C2. The significant increase of the rate CO2 is turned over in the presence of copper nanoparticles indicates that Cu nanoparticles activate hydrogen, which after spilling over to the neighbouring iron sites, facilitate a more efficient conversion of carbon dioxide.

  17. Reaction modelling of Iron Oxide Bromination in the UT-3 thermochemical cycle for Hydrogen production from water

    International Nuclear Information System (INIS)

    Amir-Rusli

    1996-01-01

    Analysis modelling of the iron oxide bromination had been carried out using experiment data from the iron oxide bromination in the UT-3 thermochemical cycle. Iron oxide in the form of pellets were made of the calcination of the mixture of iron oxide, silica, graphite and cellulose at 1473 K. Thermobalance reactor was used to study the kinetic reactions of the iron oxide bromination at a temperature of 473 K for 2 - 6 hours. The data collected from the experiments were used as input for the common models. However, none of these models could not explain the result of the experiments. A new model, a combination of two kinetic reactions : exposed particle and coated particle was created and worked successfully

  18. Mechanical properties of bio self-healing concrete containing immobilized bacteria with iron oxide nanoparticles.

    Science.gov (United States)

    Seifan, Mostafa; Sarmah, Ajit K; Samani, Ali Khajeh; Ebrahiminezhad, Alireza; Ghasemi, Younes; Berenjian, Aydin

    2018-05-01

    Concrete is arguably one of the most important and widely used materials in the world, responsible for the majority of the industrial revolution due to its unique properties. However, it is susceptible to cracking under internal and external stresses. The generated cracks result in a significant reduction in the concrete lifespan and an increase in maintenance and repair costs. In recent years, the implementation of bacterial-based healing agent in the concrete matrix has emerged as one of the most promising approaches to address the concrete cracking issue. However, the bacterial cells need to be protected from the high pH content of concrete as well as the exerted shear forces during preparation and hardening stages. To address these issues, we propose the magnetic immobilization of bacteria with iron oxide nanoparticles (IONs). In the present study, the effect of the designed bio-agent on mechanical properties of concrete (compressive strength and drying shrinkage) is investigated. The results indicate that the addition of immobilized Bacillus species with IONs in concrete matrix contributes to increasing the compressive strength. Moreover, the precipitates in the bio-concrete specimen were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The characterization studies confirm that the precipitated crystals in bio-concrete specimen were CaCO 3 , while no precipitation was observed in the control sample.

  19. Oxidation behavior of austenitic iron-base ODS alloy in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Behnamian, Y.; Dong, Z.; Zahiri, R.; Kohandehghan, A.; Mitlin, D., E-mail: behnamia@ualberta.ca, E-mail: zdong@ualberta.ca, E-mail: kohandeh@ualberta.ca, E-mail: rzahiris@ualberta.ca, E-mail: dave.mitlin@ualberta.ca [Univ. of Alberta, Edmondon, AB (Canada); Zhou, Z., E-mail: zhouzhj@mater.ustb.edu.cn [Univ. of Science and Tech. Beijing, Beijing (China); Chen, W.; Luo, J., E-mail: weixing.chen@ualberta.ca, E-mail: Jingli.luo@ualberta.ca [Univ. of Alberta, Edmonton, AB (Canada); Zheng, W., E-mail: wenyue@nrcan.gc.ca [Natural Resources Canada, Canmet MATERIALS, Hamilton, ON (Canada); Guzonas, D. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

    2014-07-01

    In this study, the effect of exposure time on the corrosion of the 304 stainless steel based oxide dispersion strengthened alloy, SS304ODS, in supercritical water was investigated at 650 {sup o}C with constant dissolved oxygen concentration. The results show that the oxidation of SS304ODS in supercritical water followed a parabolic law at 650 {sup o}C. Discontinuous oxide scale with two distinct layers has formed after 550 hours. The inner layer was chromium-rich while the outer layer was iron-rich (Magnetite). The oxide islands grow with increasing the exposure time. With increasing exposure time, the quantity of oxide islands increased in which major preferential growth along oxide-substrate interface was observed. The possible mechanism of SS304ODS oxidation in supercritical water was also discussed. (author)

  20. Iron(II) porphyrins induced conversion of nitrite into nitric oxide: A computational study.

    Science.gov (United States)

    Zhang, Ting Ting; Liu, Yong Dong; Zhong, Ru Gang

    2015-09-01

    Nitrite reduction to nitric oxide by heme proteins was reported as a protective mechanism to hypoxic injury in mammalian physiology. In this study, the pathways of nitrite reduction to nitric oxide mediated by iron(II) porphyrin (P) complexes, which were generally recognized as models for heme proteins, were investigated by using density functional theory (DFT). In view of two type isomers of combination of nitrite and Fe(II)(P), N-nitro- and O-nitrito-Fe(II)-porphyrin complexes, and two binding sites of proton to the different O atoms of nitrite moiety, four main pathways for the conversion of nitrite into nitric oxide mediated by iron(II) porphyrins were proposed. The results indicate that the pathway of N-bound Fe(II)(P)(NO2) isomer into Fe(III)(P)(NO) and water is similar to that of O-bound isomer into nitric oxide and Fe(III)(P)(OH) in both thermodynamical and dynamical aspects. Based on the initial computational studies of five-coordinate nitrite complexes, the conversion of nitrite into NO mediated by Fe(II)(P)(L) complexes with 14 kinds of proximal ligands was also investigated. Generally, the same conclusion that the pathways of N-bound isomers are similar to those of O-bound isomer was obtained for iron(II) porphyrin with ligands. Different effects of ligands on the reduction reactions were also found. It is notable that the negative proximal ligands can improve reactive abilities of N-nitro-iron(II) porphyrins in the conversion of nitrite into nitric oxide compared to neutral ligands. The findings will be helpful to expand our understanding of the mechanism of nitrite reduction to nitric oxide by iron(II) porphyrins. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Structural characterization of hog iron oxide content glasses obtained from zinc hydrometallurgy wastes

    International Nuclear Information System (INIS)

    Romero, M.; Rincon, J.M.; Musik, S.; Kozhujharov, W.

    1997-01-01

    It has been carried out the structural characterization of high oxide content glasses obtained by melting of a goethite industrial waste from the zinc hydrometallurgy with other raw materials as dolomite and glass cullet. The structural characterization has been carried out by X-ray Diffraction (XRD), X-Ray Diffraction by Amorphous Dispersion (RDF) and Mossbauer spectroscopy. It has been determined the interatomic distance, the oxidation state and the coordination of iron atoms in these glasses. (Author) 16 refs

  2. Nitric oxide maintains cell survival of Trichomonas vaginalis upon iron depletion.

    Science.gov (United States)

    Cheng, Wei-Hung; Huang, Kuo-Yang; Huang, Po-Jung; Hsu, Jo-Hsuan; Fang, Yi-Kai; Chiu, Cheng-Hsun; Tang, Petrus

    2015-07-25

    Iron plays a pivotal role in the pathogenesis of Trichomonas vaginalis, the causative agent of highly prevalent human trichomoniasis. T. vaginalis resides in the vaginal region, where the iron concentration is constantly changing. Hence, T. vaginalis must adapt to variations in iron availability to establish and maintain an infection. The free radical signaling molecules reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been proven to participate in iron deficiency in eukaryotes. However, little is known about the roles of these molecules in iron-deficient T. vaginalis. T. vaginalis cultured in iron-rich and -deficient conditions were collected for all experiments in this study. Next generation RNA sequencing was conducted to investigate the impact of iron on transcriptome of T. vaginalis. The cell viabilities were monitored after the trophozoites treated with the inhibitors of nitric oxide (NO) synthase (L-NG-monomethyl arginine, L-NMMA) and proteasome (MG132). Hydrogenosomal membrane potential was measured using JC-1 staining. We demonstrated that NO rather than ROS accumulates in iron-deficient T. vaginalis. The level of NO was blocked by MG132 and L-NMMA, indicating that NO production is through a proteasome and arginine dependent pathway. We found that the inhibition of proteasome activity shortened the survival of iron-deficient cells compared with untreated iron-deficient cells. Surprisingly, the addition of arginine restored both NO level and the survival of proteasome-inhibited cells, suggesting that proteasome-derived NO is crucial for cell survival under iron-limited conditions. Additionally, NO maintains the hydrogenosomal membrane potential, a determinant for cell survival, emphasizing the cytoprotective effect of NO on iron-deficient T. vaginalis. Collectively, we determined that NO produced by the proteasome prolonged the survival of iron-deficient T. vaginalis via maintenance of the hydrogenosomal functions. The findings in this

  3. Tin oxide quantum dots embedded iron oxide composite as efficient lead sensor

    Science.gov (United States)

    Dutta, Dipa; Bahadur, Dhirendra

    2018-04-01

    SnO2 quantum dots (QDs) embedded iron oxide (IO) nanocomposite is fabricated and explored as a capable sensor for lead detection. Square wave anodic stripping voltammetry (SWASV) and amperometry have been used to explore the proposed sensor's response towards lead detection. The modified electrode shows linear current response for concentration of lead ranging from 99 nM to 6.6 µM with limit of detection 0.42 µM (34 ppb). Amperometry shows a detection limit as low as 0.18 nM (0.015 ppb); which is far below the permissible limit of lead in drinking water by World Health Organization. This proposed sensor shows linear current response (R2 = 0.98) for the lead concentration ranging from 133 × 10-9 to 4.4 × 10-6M. It also exhibits rapid response time of 12 sec with an ultra high sensitivity of 5.5 µA/nM. These detection properties promise the use of SnO2 QDs -IO composite for detection of lead in environmental sample with great ease.

  4. Oxidative stress response in neural stem cells exposed to different superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Pongrac, Igor M; Pavičić, Ivan; Milić, Mirta; Brkić Ahmed, Lada; Babič, Michal; Horák, Daniel; Vinković Vrček, Ivana; Gajović, Srećko

    2016-01-01

    Biocompatibility, safety, and risk assessments of superparamagnetic iron oxide nanoparticles (SPIONs) are of the highest priority in researching their application in biomedicine. One improvement in the biological properties of SPIONs may be achieved by different functionalization and surface modifications. This study aims to investigate how a different surface functionalization of SPIONs - uncoated, coated with d-mannose, or coated with poly-l-lysine - affects biocompatibility. We sought to investigate murine neural stem cells (NSCs) as important model system for regenerative medicine. To reveal the possible mechanism of toxicity of SPIONs on NSCs, levels of reactive oxygen species, intracellular glutathione, mitochondrial membrane potential, cell-membrane potential, DNA damage, and activities of SOD and GPx were examined. Even in cases where reactive oxygen species levels were significantly lowered in NSCs exposed to SPIONs, we found depleted intracellular glutathione levels, altered activities of SOD and GPx, hyperpolarization of the mitochondrial membrane, dissipated cell-membrane potential, and increased DNA damage, irrespective of the surface coating applied for SPION stabilization. Although surface coating should prevent the toxic effects of SPIONs, our results showed that all of the tested SPION types affected the NSCs similarly, indicating that mitochondrial homeostasis is their major cellular target. Despite the claimed biomedical benefits of SPIONs, the refined determination of their effects on various cellular functions presented in this work highlights the need for further safety evaluations. This investigation helps to fill the knowledge gaps on the criteria that should be considered in evaluating the biocompatibility and safety of novel nanoparticles.

  5. In situ reduction of as-prepared γ-Iron Oxide Nanoparticles

    DEFF Research Database (Denmark)

    Garbus, Pelle Gorm; Ahlburg, Jakob; Christensen, Mogens

    -ray diffraction measurement. The as-prepared maghemite nanoparticles were synthesized by the continuous decomposition of solutes in supercritical hydrothermal flow synthesis [3, 4]. The reagent used was ferric ammonium citrate (C6H8O7•xFe(III)•yNH3) that under hydrothermal flow synthesis decomposes into the γ......-iron oxide Fe2O3. The reduction of maghemite to body centered cubic (BCC) iron does not go through a detectable intermediate state.1.Jensen, K.M., et al., Mechanisms for iron oxide formation under hydrothermal conditions: an in situ total scattering study. ACS nano, 2014. 8(10): p. 10704-10714.2.Andersen, H...

  6. Current status of superparamagnetic iron oxide contrast agents for liver magnetic resonance imaging.

    Science.gov (United States)

    Wang, Yi-Xiang J

    2015-12-21

    Five types of superparamagnetic iron oxide (SPIO), i.e. Ferumoxides (Feridex(®) IV, Berlex Laboratories), Ferucarbotran (Resovist(®), Bayer Healthcare), Ferumoxtran-10 (AMI-227 or Code-7227, Combidex(®), AMAG Pharma; Sinerem(®), Guerbet), NC100150 (Clariscan(®), Nycomed,) and (VSOP C184, Ferropharm) have been designed and clinically tested as magnetic resonance contrast agents. However, until now Resovist(®) is current available in only a few countries. The other four agents have been stopped for further development or withdrawn from the market. Another SPIO agent Ferumoxytol (Feraheme(®)) is approved for the treatment of iron deficiency in adult chronic kidney disease patients. Ferumoxytol is comprised of iron oxide particles surrounded by a carbohydrate coat, and it is being explored as a potential imaging approach for evaluating lymph nodes and certain liver tumors.

  7. A novel thermal decomposition approach for the synthesis of silica-iron oxide core–shell nanoparticles

    International Nuclear Information System (INIS)

    Kishore, P.N.R.; Jeevanandam, P.

    2012-01-01

    Highlights: ► Silica-iron oxide core–shell nanoparticles have been synthesized by a novel thermal decomposition approach. ► The silica-iron oxide core–shell nanoparticles are superparamagnetic at room temperature. ► The silica-iron oxide core–shell nanoparticles serve as good photocatalyst for the degradation of Rhodamine B. - Abstract: A simple thermal decomposition approach for the synthesis of magnetic nanoparticles consisting of silica as core and iron oxide nanoparticles as shell has been reported. The iron oxide nanoparticles were deposited on the silica spheres (mean diameter = 244 ± 13 nm) by the thermal decomposition of iron (III) acetylacetonate, in diphenyl ether, in the presence of SiO 2 . The core–shell nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, field emission-scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy, diffuse reflectance spectroscopy, and magnetic measurements. The results confirm the presence of iron oxide nanoparticles on the silica core. The core–shell nanoparticles are superparamagnetic at room temperature indicating the presence of iron oxide nanoparticles on silica. The core–shell nanoparticles have been demonstrated as good photocatalyst for the degradation of Rhodamine B.

  8. Oxidation of adsorbed ferrous iron: kinetics and influence of process conditions.

    Science.gov (United States)

    Buamah, R; Petrusevski, B; Schippers, J C

    2009-01-01

    For the removal of iron from groundwater, aeration followed with rapid (sand) filtration is frequently applied. Iron removal in this process is achieved through oxidation of Fe(2 + ) in aqueous solution followed by floc formation as well as adsorption of Fe(2 + ) onto the filter media. The rate of oxidation of the adsorbed Fe(2 + ) on the filter media plays an important role in this removal process. This study focuses on investigating the effect of pH on the rate of oxidation of adsorbed Fe(2 + ). Fe(2 + ) has been adsorbed, under anoxic conditions, on iron oxide coated sand (IOCS) in a short filter column and subsequently oxidized by feeding the column with aerated water. Ferrous ions adsorbed at pH 5, 6, 7 and 8 demonstrated consumption of oxygen, when aerated water was fed into the column. The oxygen uptake at pH 7 and 8 was faster than at pH 5 and 6. However the difference was less pronounced than expected. The difference is attributed to the pH buffering effect of the IOCS. At feedwater pH 5, 6 and 7 the pH in the effluent was higher than in the influent, while a pH drop should occur because of oxidation of adsorbed Fe(2 + ). At pH 8, the pH dropped. These phenomena are attributed to the presence of calcium and /or ferrous carbonate in IOCS.

  9. Magnetically-modified natural biogenic iron oxides for organic xenobiotics removal

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Filip, J.; Horská, Kateřina; Nowakova, M.; Tuček, J.; Šafaříková, Miroslava; Hashimoto, H.; Takada, J.; Zbořil, R.

    2015-01-01

    Roč. 12, č. 2 (2015), s. 673-682 ISSN 1735-1472 R&D Projects: GA MŠk(CZ) LH11111; GA MŠk LH12190 Institutional support: RVO:67179843 Keywords : Biogenic iron oxides * Leptothrix ochracea * Magnetic fluid * Magnetic adsorbents * Xenobiotics Subject RIV: EI - Biotechnology ; Bionics Impact factor: 2.344, year: 2015

  10. Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

    Czech Academy of Sciences Publication Activity Database

    Henych, Jiří; Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš; Janoš, P.; Kuráň, P.; Šťastný, M.

    2015-01-01

    Roč. 344, JUL (2015), s. 9-16 ISSN 0169-4332 R&D Projects: GA ČR(CZ) GAP106/12/1116 Institutional support: RVO:61388980 Keywords : Titania-iron oxides * Homogeneous hydrolysis * Degradation of organophosphates * Parathion methyl Subject RIV: CA - Inorganic Chemistry Impact factor: 3.150, year: 2015

  11. Size distribution of magnetic iron oxide nanoparticles using Warren-Averbach XRD analysis

    Science.gov (United States)

    Mahadevan, S.; Behera, S. P.; Gnanaprakash, G.; Jayakumar, T.; Philip, J.; Rao, B. P. C.

    2012-07-01

    We use the Fourier transform based Warren-Averbach (WA) analysis to separate the contributions of X-ray diffraction (XRD) profile broadening due to crystallite size and microstrain for magnetic iron oxide nanoparticles. The profile shape of the column length distribution, obtained from WA analysis, is used to analyze the shape of the magnetic iron oxide nanoparticles. From the column length distribution, the crystallite size and its distribution are estimated for these nanoparticles which are compared with size distribution obtained from dynamic light scattering measurements. The crystallite size and size distribution of crystallites obtained from WA analysis are explained based on the experimental parameters employed in preparation of these magnetic iron oxide nanoparticles. The variation of volume weighted diameter (Dv, from WA analysis) with saturation magnetization (Ms) fits well to a core shell model wherein it is known that Ms=Mbulk(1-6g/Dv) with Mbulk as bulk magnetization of iron oxide and g as magnetic shell disorder thickness.

  12. Leptothrix sp sheaths modified with iron oxide particles: Magnetically responsive, high aspect ratio functional material

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Angelova, R.; Baldíková, E.; Pospíšková, K.; Šafaříková, Miroslava

    2017-01-01

    Roč. 71, February (2017), s. 1342-1346 ISSN 0928-4931 Institutional support: RVO:60077344 Keywords : Leptothrix * magnetic modification * iron oxide * high aspect ratio material Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Materials engineering Impact factor: 4.164, year: 2016

  13. Alternating magnetic field energy absorption in the dispersion of iron oxide nanoparticles in a viscous medium

    Czech Academy of Sciences Publication Activity Database

    Smolkova, I.S.; Kazantseva, N.E.; Babayan, V.; Smolka, P.; Parmar, H.; Vilcakova, J.; Schneeweiss, Oldřich; Pizúrová, Naděžda

    2015-01-01

    Roč. 374, JAN (2015), s. 508-515 ISSN 0304-8853 Institutional support: RVO:68081723 Keywords : Iron oxide nanoparticles * Coprecipitation * Magnetic interactions * Specific loss power * Hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.357, year: 2015

  14. Phosphorus binding by poorly crystalline iron oxides in North Sea sediments

    NARCIS (Netherlands)

    Slomp, C.P.; Gaast, S. J. van der; Raaphorst, W. van

    1996-01-01

    Differential X-ray powder diffraction (DXRD) and extraction procedures were used to characterize the iron oxides present in four sediments from contrasting environments in the North Sea. Stations were located in depositional areas on the southern shelf (German Bight) and on the north-eastern

  15. Hysteresis losses in iron oxide nanoparticles prepared by glass crystallization or wet chemical precipitation

    International Nuclear Information System (INIS)

    Mueller, Robert; Dutz, Silvio; Hergt, Rudolf; Schmidt, Christopher; Steinmetz, Hanna; Zeisberger, Matthias; Gawalek, Wolfgang

    2007-01-01

    Ferrofluids were prepared from glass crystallized as well as wet precipitated iron oxide particles. Comparing hysteresis losses versus applied field amplitude from particles in immobilized state (powder) and in fluid state (ferrofluid) shows in some cases anomalous large losses at low magnetic fields. The influence of texture on the losses was investigated

  16. Multifunctional Silver Coated E-33/Iron Oxide Water Filters: Inhibition of Biofilm Growth and Arsenic Removal

    Science.gov (United States)

    Bayoxide® E33 (E-33, Goethite) is a widely used commercial material for arsenic adsorption. It is a mixture of iron oxyhydroxide and oxides. E-33 is primarily used to remove arsenic from water and to a lesser extent, other anions, but generally lacks multifunctuality. It is a non...

  17. In-Situ Regeneration of Saturated Granular Activated Carbon by an Iron Oxide Nanocatalyst

    Science.gov (United States)

    Granular activated carbon (GAC) can remove trace organic pollutants and natural organic matter (NOM) from industrial and municipal waters. This paper evaluates an iron nanocatalyst approach, based on Fenton-like oxidation reactions, to regenerate spent GAC within a packed bed con...

  18. The electrochemical transfer reactions and the structure of the iron|oxide layer|electrolyte interface

    International Nuclear Information System (INIS)

    Petrović, Željka; Metikoš-Huković, Mirjana; Babić, Ranko

    2012-01-01

    The thickness, barrier (protecting) and semiconducting properties of the potentiostatically formed oxide films on the pure iron electrode in an aqueous borate buffer solution were investigated by electrochemical quartz crystal nanobalance (EQCN), electrochemical impedance spectroscopy (EIS), and Mott–Schottky (MS) analysis. The thicknesses of the prepassive Fe(II)hydroxide layer (up to monolayer) nucleated on the bare iron surface and the passive Fe(II)/Fe(III) layer (up to 2 nm), deposited on the top of the first one, were determined using in situ gravimetry. Electronic properties of iron prepassive and passive films as well as ionic and electronic transfer reactions at the film|solution interface were discussed on the basis of a band structure model of the surface oxide film and the potential distribution at the interface. The anodic oxide film formation and cathodic decomposition are coupled processes and their reversible inter-conversion is mediated by the availability of free charge carriers on the electrode|solution interface. The structure of the reversible double layer at the iron oxide|solution interface was discussed based on the concept of the specific adsorption of the imidazolium cation on the negatively charged electrode surface at pH > pH pzc .

  19. Internalization of annexin A5-functionalized iron oxide particles by apoptotic Jurkat cells

    NARCIS (Netherlands)

    van Tilborg, Geralda A. F.; Geelen, Tessa; Duimel, Hans; Bomans, Paul H. H.; Frederik, Peter M.; Sanders, Honorius M. H. F.; Deckers, Niko M.; Deckers, Roel; Reutelingsperger, Chris P. M.; Strijkers, Gustav J.; Nicolay, Klaas

    2009-01-01

    Apoptosis plays an important role in the etiology of various diseases. Several studies have reported on the use of annexin A5-functionalized iron oxide particles for the detection of apoptosis with MRI, both in vitro and in vivo. The protein annexin A5 binds with high affinity to the phospholipid

  20. Integrated iron(II) oxidation and limestone neutralisation of acid mine water

    CSIR Research Space (South Africa)

    Maree, JP

    1999-01-01

    Full Text Available dependent on the surface area exposed to the liquid (RSA) and the OH-, oxygen, CaCO3, suspended solids and iron (II) concentrations, and less dependent on specific surface area (SSA) and pressure in the pH range 5 to 6, The chemical oxidation rate (p...

  1. Au/iron oxide catalysts: temperature programmed reduction and X-ray diffraction characterization

    International Nuclear Information System (INIS)

    Neri, G.; Visco, A.M.; Galvagno, S.; Donato, A.; Panzalorto, M.

    1999-01-01

    Gold on iron oxides catalysts have been characterized by temperature programmed reduction (TPR) and X-ray diffraction spectroscopy (XRD). The influence of preparation method, gold loading and pretreatment conditions on the reducibility of iron oxides have been investigated. On the impregnated Au/iron oxide catalysts as well as on the support alone the partial reduction of Fe(III) oxy(hydroxides) to Fe 3 O 4 starts in the 550 and 700 K temperature range. On the coprecipitated samples, the temperature of formation of Fe 3 O 4 is strongly dependent on the presence of gold. The reduction temperature is lowered as the gold loading is increased. The reduction of Fe 3 O 4 to FeO occurs at about 900 K and is not dependent on the presence of gold and the preparation method. It is suggested that the effect of gold on the reducibility of the iron oxides is related to an increase of the structural defects and/or of the surface hydroxyl groups. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  2. Iron oxide impregnated filter paper (Pi test): a review of its development and methodological research

    NARCIS (Netherlands)

    Chardon, W.J.; Menon, R.G.; Chien, S.H.

    1996-01-01

    Iron oxide impregnated filter paper (FeO paper) has been used to study the availability of phosphorus (P) to plants and algae, P desorption kinetics and P dynamics in the field. Since its initial development a number of differences in the method of preparation of the paper and its application have

  3. Iron Oxide Nanoparticle-Based Magnetic Ink Development for Fully Printed Tunable Radio-Frequency Devices

    KAUST Repository

    Vaseem, Mohammad

    2018-01-30

    The field of printed electronics is still in its infancy and most of the reported work is based on commercially available nanoparticle-based metallic inks. Although fully printed devices that employ dielectric/semiconductor inks have recently been reported, there is a dearth of functional inks that can demonstrate controllable devices. The lack of availability of functional inks is a barrier to the widespread use of fully printed devices. For radio-frequency electronics, magnetic materials have many uses in reconfigurable components but rely on expensive and rigid ferrite materials. A suitable magnetic ink can facilitate the realization of fully printed, magnetically controlled, tunable devices. This report presents the development of an iron oxide nanoparticle-based magnetic ink. First, a tunable inductor is fully printed using iron oxide nanoparticle-based magnetic ink. Furthermore, iron oxide nanoparticles are functionalized with oleic acid to make them compatible with a UV-curable SU8 solution. Functionalized iron oxide nanoparticles are successfully embedded in the SU8 matrix to make a magnetic substrate. The as-fabricated substrate is characterized for its magnetostatic and microwave properties. A frequency tunable printed patch antenna is demonstrated using the magnetic and in-house silver-organo-complex inks. This is a step toward low-cost, fully printed, controllable electronic components.

  4. Rapid determination of iron oxide content in magnetically modified particulate materials

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Nýdlová, L.; Pospíšková, K.; Baldíková, E.; Maděrová, Z.; Šafaříková, Miroslava

    2016-01-01

    Roč. 26, June (2016), s. 114-117 ISSN 1674-2001 Institutional support: RVO:60077344 Keywords : magnetic iron oxide s * magnetic permeability meter * magnetically modified materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.621, year: 2016

  5. Photosensitizer conjugated iron oxide nanoparticles for simultaneous in vitro magneto-fluorescent imaging guided photodynamic therapy.

    Science.gov (United States)

    Nafiujjaman, Md; Revuri, Vishnu; Nurunnabi, Md; Cho, Kwang Jae; Lee, Yong-Kyu

    2015-04-04

    In this study, photosensitizer conjugated iron oxide nanoparticles were strategically designed and prepared for simultaneous PDT and dual-mode fluorescence/MR imaging. The MRI contrast agent Fe3O4 was modified by APTES to functionalize the surface and further to link with heparin-pheophorbide-A conjugates.

  6. Evaluation of iron oxide nanoparticle micelles for Magnetic Particle Imaging (MPI) of thrombosis

    NARCIS (Netherlands)

    Starmans, L.W.E.; Moonen, R.P.M.; Aussems-Custers, E.; Daemen, M.J.A.P.; Strijkers, G. J.; Nicolay, K.; Grüll, H.

    2015-01-01

    Magnetic particle imaging (MPI) is an emerging medical imaging modality that directly visualizes magnetic particles in a hot-spot like fashion. We recently developed an iron oxide nanoparticle-micelle (ION-Micelle) platform that allows highly sensitive MPI. The goal of this study was to assess the

  7. Some aspects concerning the characterization of iron oxides and hydroxides in soils and clays

    International Nuclear Information System (INIS)

    Vandenberghe, R.E.; Grave, E. de; Landuydt, C.; Bowen, L.H.

    1990-01-01

    A review of the systematic Moessbauer studies on the most encountered iron oxides and hydroxides is given in which the qualitative and quantitative aspects, helpful in the characterization of natural samples, are emphasized. The present possibilities of Moessbauer spectroscopy in soil characterization are further illustrated from some examples of natural soils. (orig.)

  8. Integrity of 111In-radiolabeled superparamagnetic iron oxide nanoparticles in the mouse

    International Nuclear Information System (INIS)

    Wang, Haotian; Kumar, Rajiv; Nagesha, Dattatri; Duclos, Richard I.; Sridhar, Srinivas; Gatley, Samuel J.

    2015-01-01

    Introduction: Iron-oxide nanoparticles can act as contrast agents in magnetic resonance imaging (MRI), while radiolabeling the same platform with nuclear medicine isotopes allows imaging with positron emission tomography (PET) or single-photon emission computed tomography (SPECT), modalities that offer better quantification. For successful translation of these multifunctional imaging platforms to clinical use, it is imperative to evaluate the degree to which the association between radioactive label and iron oxide core remains intact in vivo. Methods: We prepared iron oxide nanoparticles stabilized by oleic acid and phospholipids which were further radiolabeled with 59 Fe, 14 C-oleic acid, and 111 In. Results: Mouse biodistributions showed 111 In preferentially localized in reticuloendothelial organs, liver, spleen and bone. However, there were greater levels of 59 Fe than 111 In in liver and spleen, but lower levels of 14 C. Conclusions: While there is some degree of dissociation between the 111 In labeled component of the nanoparticle and the iron oxide core, there is extensive dissociation of the oleic acid component

  9. Pluriformity of inflammation in multiple sclerosis shown by ultra-small iron oxide particle enhancement

    NARCIS (Netherlands)

    Vellinga, M.M.; Oude Engberink, R.D.; Seewann, A.; Pouwels, P.J.W.; Wattjes, M.P.; van der Pol, S.M.A.; Pering, C.; Polman, C.H.; de Vries, H.E.; Geurts, J.J.G.; Barkhof, F.

    2008-01-01

    Gadolinium-DTPA (Gd-DTPA) is routinely used as a marker for inflammation in MRI to visualize breakdown of the blood-brain barrier (BBB) in multiple sclerosis. Recent data suggest that ultra-small superparamagnetic particles of iron oxide (USPIO) can be used to visualize cellular infiltration,

  10. Iron Amendment and Fenton Oxidation of MTBE-Spent Granular Activated Carbon

    Science.gov (United States)

    Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves Fe amendment to the GAC to catalyze H2O2 reactions and to enhance the rate of MTBE oxidation and GAC regeneration. Four forms of iron (ferric sulfate, ferric chloride, fer...

  11. Attenuation of iron-binding proteins in ARPE-19 cells reduces their resistance to oxidative stress.

    Science.gov (United States)

    Karlsson, Markus; Kurz, Tino

    2016-09-01

    Oxidative stress-related damage to retinal pigment epithelial (RPE) cells is an important feature in the development of age-related macular degeneration. Iron-catalysed intralysosomal production of hydroxyl radicals is considered a major pathogenic factor, leading to lipofuscin formation with ensuing depressed cellular autophagic capacity, lysosomal membrane permeabilization and apoptosis. Previously, we have shown that cultured immortalized human RPE (ARPE-19) cells are extremely resistant to exposure to bolus doses of hydrogen peroxide and contain considerable amounts of the iron-binding proteins metallothionein (MT), heat-shock protein 70 (HSP70) and ferritin (FT). According to previous findings, autophagy of these proteins depresses lysosomal redox-active iron. The aim of this study was to investigate whether up- or downregulation of these proteins would affect the resistance of ARPE-19 cells to oxidative stress. The sensitivity of ARPE-19 cells to H2 O2 exposure was tested following upregulation of MT, HSP70 and/or FT by pretreatment with ZnSO4 , heat shock or FeCl3 , as well as siRNA-mediated downregulation of the same proteins. Upregulation of MT, HSP70 and FT did not improve survival following exposure to H2 O2 . This was interpreted as existence of an already maximal protection. Combined siRNA-mediated attenuation of both FT chains (H and L), or simultaneous downregulation of all three proteins, made the cells significantly more susceptible to oxidative stress confirming the importance of iron-binding proteins. The findings support our hypothesis that the oxidative stress resistance exhibited by RPE cells may be explained by a high autophagic influx of iron-binding proteins that would keep levels of redox-active lysosomal iron low. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  12. Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui, E-mail: sgzhou@soil.gd.cn

    2015-08-15

    Highlights: • Paddy soil contaminated with benzoate incubated with hematite and magnetite. • Iron oxides addition enhanced methanogenic benzoate degradation by 25–53%. • The facilitated syntrophy might involve direct interspecies electron transfer. • Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved. - Abstract: Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89–94% of the electrons released from benzoate oxidation were recovered in CH{sub 4} production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.

  13. Controlling lipid oxidation via a biomimetic iron chelating active packaging material.

    Science.gov (United States)

    Tian, Fang; Decker, Eric A; Goddard, Julie M

    2013-12-18

    Previously, a siderophore-mimetic metal chelating active packaging film was developed by grafting poly(hydroxamic acid) (PHA) from the surface of polypropylene (PP) films. The objective of the current work was to demonstrate the potential applicability of this PP-g-PHA film to control iron-promoted lipid oxidation in food emulsions. The iron chelating activity of this film was investigated, and the surface chemistry and color intensity of films were also analyzed after iron chelation. In comparison to the iron chelating activity in the free Fe(3+) solution, the PP-g-PHA film retained approximately 50 and 30% of its activity in nitrilotriacetic acid (NTA)/Fe(3+) and citric acid/Fe(3+) solutions, respectively (pH 5.0), indicating a strong chelating strength for iron. The ability of PP-g-PHA films to control lipid oxidation was demonstrated in a model emulsion system (pH 3.0). PP-g-PHA films performed even better than ethylenediaminetetraacetic acid (EDTA) in preventing the formation of volatile oxidation products. The particle size and ζ potential results of emulsions indicated that PP-g-PHA films had no adverse effects on the stability of the emulsion system. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis suggested a non-migratory nature of the PP-g-PHA film surface. These results suggest that such biomimetic, non-migratory metal chelating active packaging films have commercial potential in protecting foods against iron-promoted lipid oxidation.

  14. Iron-Mediated Oxidation of Methoxyhydroquinone under Dark Conditions: Kinetic and Mechanistic Insights.

    Science.gov (United States)

    Yuan, Xiu; Davis, James A; Nico, Peter S

    2016-02-16

    Despite the biogeochemical significance of the interactions between natural organic matter (NOM) and iron species, considerable uncertainty still remains as to the exact processes contributing to the rates and extents of complexation and redox reactions between these important and complex environmental components. Investigations on the reactivity of low-molecular-weight quinones, which are believed to be key redox active compounds within NOM, toward iron species, could provide considerable insight into the kinetics and mechanisms of reactions involving NOM and iron. In this study, the oxidation of 2-methoxyhydroquinone (MH2Q) by ferric iron (Fe(III)) under dark conditions in the absence and presence of oxygen was investigated within a pH range of 4-6. Although Fe(III) was capable of stoichiometrically oxidizing MH2Q under anaerobic conditions, catalytic oxidation of MH2Q was observed in the presence of O2 due to further cycling between oxygen, semiquinone radicals, and iron species. A detailed kinetic model was developed to describe the predominant mechanisms, which indicated that both the undissociated and monodissociated anions of MH2Q were kinetically active species toward Fe(III) reduction, with the monodissociated anion being the key species accounting for the pH dependence of the oxidation. The generated radical intermediates, namely semiquinone and superoxide, are of great importance in reaction-chain propagation. The kinetic model may provide critical insight into the underlying mechanisms of the thermodynamic and kinetic characteristics of metal-organic interactions and assist in understanding and predicting the factors controlling iron and organic matter transformation and bioavailability in aquatic systems.

  15. Iron and iron oxide nanoparticles are highly toxic to Culex quinquefasciatus with little non-target effects on larvivorous fishes.

    Science.gov (United States)

    Murugan, Kadarkarai; Dinesh, Devakumar; Nataraj, Devaraj; Subramaniam, Jayapal; Amuthavalli, Pandiyan; Madhavan, Jagannathan; Rajasekar, Aruliah; Rajan, Mariappan; Thiruppathi, Kulandhaivel Palani; Kumar, Suresh; Higuchi, Akon; Nicoletti, Marcello; Benelli, Giovanni

    2018-04-01

    The control of filariasis vectors has been enhanced in several areas, but there are main challenges, including increasing resistance to insecticides and lack of cheap and eco-friendly products. The toxicity of iron (Fe 0 ) and iron oxide (Fe 2 O 3 ) nanoparticles has been scarcely investigated yet. We studied the larvicidal and pupicidal activity of Fe 0 and Fe 2 O 3 nanoparticles against Culex quinquefasciatus. Fe 0 and Fe 2 O 3 nanoparticles produced by green (using a Ficus natalensis aqueous extract) and chemical nanosynthesis, respectively, were analyzed by UV-Vis spectrophotometry, FT-IR spectroscopy, XRD analysis, SEM, and EDX assays. In larvicidal and pupicidal experiments on Cx. quinquefasciatus, LC 50 of Fe 0 nanoparticles ranged from 20.9 (I instar larvae) to 43.7 ppm (pupae) and from 4.5 (I) to 22.1 ppm (pupae) for Fe 2 O 3 nanoparticles synthesized chemically. Furthermore, the predation efficiency of the guppy fish, Poecilia reticulata, after a single treatment with sub-lethal doses of Fe 0 and Fe 2 O 3 nanoparticles was magnified. Overall, this work provides new insights about the toxicity of Fe 0 and Fe 2 O 3 nanoparticles against mosquito vectors; we suggested that green and chemical fabricated nano-iron may be considered to develop novel and effective pesticides.

  16. Strain induced anomalous red shift in mesoscopic iron oxide

    Indian Academy of Sciences (India)

    Nano magnetic oxides; red shift; magnetic storage. ... size and strain induced modifications of various physical properties viz. optical, magnetic and structural. ... ∼2, are synthesized by employing starch and ethylene glycol and starch and ...

  17. Immunological effects of iron oxide nanoparticles and iron-based complex drug formulations: Therapeutic benefits, toxicity, mechanistic insights, and translational considerations.

    Science.gov (United States)

    Shah, Ankit; Dobrovolskaia, Marina A

    2018-04-01

    Nanotechnology offers several advantages for drug delivery. However, there is the need for addressing potential safety concerns regarding the adverse health effects of these unique materials. Some such effects may occur due to undesirable interactions between nanoparticles and the immune system, and they may include hypersensitivity reactions, immunosuppression, and immunostimulation. While strategies, models, and approaches for studying the immunological safety of various engineered nanoparticles, including metal oxides, have been covered in the current literature, little attention has been given to the interactions between iron oxide-based nanomaterials and various components of the immune system. Here we provide a comprehensive review of studies investigating the effects of iron oxides and iron-based nanoparticles on various types of immune cells, highlight current gaps in the understanding of the structure-activity relationships of these materials, and propose a framework for capturing their immunotoxicity to streamline comparative studies between various types of iron-based formulations. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. Iron-rich Oxides at the Core-mantle Boundary

    Science.gov (United States)

    Wicks, J. K.; Jackson, J. M.; Sturhahn, W.; Bower, D. J.; Zhuravlev, K. K.; Prakapenka, V.

    2013-12-01

    Seismic observations near the base of the core-mantle boundary (CMB) have detected 5-20 km thick patches in which the seismic wave velocities are reduced by up to 30%. These ultra-low velocity zones (ULVZs) have been interpreted as aggregates of partially molten material (e.g. Williams and Garnero 1996, Hernlund and Jellinek, 2010) or as solid, iron-enriched residues (e.g. Knittle and Jeanloz, 1991; Mao et al., 2006; Wicks et al., 2010), typically based on proposed sources of velocity reduction. The stabilities of these structure types have been explored through dynamic models that have assembled a relationship between ULVZ stability and density (Hernlund and Tackley, 2007; Bower et al., 2010). Now, to constrain the chemistry and mineralogy of ULVZs, more information is needed on the relationship between density and sound velocity of candidate phases. We present the pressure-volume-temperature equation of state of (Mg0.06 57Fe0.94)O determined up to pressures of 120 GPa and temperatures of 2000 K. Volume was measured with X-ray diffraction at beamline 13-ID-D of the Advanced Photon Source (APS), where high pressures and temperatures are achieved in a diamond anvil cell with in-situ laser heating. Sample assemblies were prepared using dehydrated NaCl as an insulator and neon as a pressure transmitting medium. We present results with and without iron as a buffer and thermal pressure gauge. We have also determined the room temperature Debye velocity (VD) of (Mg0.06 57Fe0.94)O using nuclear resonant inelastic x-ray scattering and in-situ X-ray diffraction, up to 80 GPa at 3-ID-B of the APS. The effect of the electronic environment of the iron sites on the velocities was tracked in-situ using synchrotron Moessbauer spectroscopy. Using our measured equation of state, the seismically relevant compressional (VP) and shear (VS) wave velocities were calculated from the Debye velocities. We combine these studies with a simple mixing model to predict the properties of a solid

  19. Cell tagging with clinically approved iron oxides: feasibility and effect of lipofection, particle size, and surface coating on labeling efficiency.

    Science.gov (United States)

    Matuszewski, Lars; Persigehl, Thorsten; Wall, Alexander; Schwindt, Wolfram; Tombach, Bernd; Fobker, Manfred; Poremba, Christopher; Ebert, Wolfgang; Heindel, Walter; Bremer, Christoph

    2005-04-01

    To evaluate the effect of lipofection, particle size, and surface coating on labeling efficiency of mammalian cells with superparamagnetic iron oxides (SPIOs). Institutional Review Board approval was not required. Different human cell lines (lung and breast cancer, fibrosarcoma, leukocytes) were tagged by using carboxydextran-coated SPIOs of various hydrodynamic diameters (17-65 nm) and a dextran-coated iron oxide (150 nm). Cells were incubated with increasing concentrations of iron (0.01-1.00 mg of iron [Fe] per milliliter), including or excluding a transfection medium (TM). Cellular iron uptake was analyzed qualitatively at light and electron microscopy and was quantified at atomic emission spectroscopy. Cell visibility was assessed with gradient- and spin-echo magnetic resonance (MR) imaging. Effects of iron concentration in the medium and of lipofection on cellular SPIO uptake were analyzed with analysis of variance and two-tailed Student t test, respectively. Iron oxide uptake increased in a dose-dependent manner with higher iron concentrations in the medium. The TM significantly increased the iron load of cells (up to 2.6-fold, P .05). As few as 10 000 cells could be detected with clinically available MR techniques by using this approach. Lipofection-based cell tagging is a simple method for efficient cell labeling with clinically approved iron oxide-based contrast agents. Large particle size and carboxydextran coating are preferable for cell tagging with endocytosis- and lipofection-based methods. (c) RSNA, 2005.

  20. Photodegradation of orange I in the heterogeneous iron oxide-oxalate complex system under UVA irradiation

    International Nuclear Information System (INIS)

    Lei, Jing; Liu Chengshuai; Li Fangbai; Li Xiaomin; Zhou Shungui; Liu Tongxu; Gu Minghua; Wu Qitang

    2006-01-01

    To understand the photodegradation of azo dyes in natural aquatic environment, a novel photo-Fenton-like system, the heterogeneous iron oxide-oxalate complex system was set up with the existence of iron oxides and oxalate. Five iron oxides, including γ-FeOOH, IO-250, IO-320, IO-420 and IO-520, were prepared and their adsorption capacity was investigated in the dark. The results showed that the saturated adsorption amount (Γ max ) was ranked the order of IO-250>IO-320>γ-FeOOH>IO-420>IO-520 and the adsorption equilibrium constant (K a ) followed the order of IO-250>IO-520>γ-FeOOH>IO-420>IO-320. The effect of initial pH value, the initial concentrations of oxalate and orange I on the photodegradation of orange I were also investigated in different iron oxide-oxalate systems. The results showed that the photodegradation of orange I under UVA irradiation could be enhanced greatly in the presence of oxalate. And the optimal oxalate concentrations (C ox 0 ) for γ-FeOOH, IO-250, IO-320, IO-420 and IO-520 were 1.8, 1.6, 3.5, 3.0 and 0.8mM, respectively. The photodegradation of orange I in the presence of optimal C ox 0 was ranked as the order of γ-FeOOH>IO-250>IO-320>IO-420>IO-520. The optimal range of initial pH was at about 3-4. The first-order kinetic constant for the degradation of orange I decreased with the increase in the initial concentration of orange I. Furthermore, the variation of pH, the concentrations of Fe 3+ and Fe 2+ during the photoreaction were also strongly dependent on the C ox 0 and iron oxides

  1. Solid-stabilized emulsion formation using stearoyl lactylate coated iron oxide nanoparticles

    Science.gov (United States)

    Vengsarkar, Pranav S.; Roberts, Christopher B.

    2014-10-01

    Iron oxide nanoparticles can exhibit highly tunable physicochemical properties that are extremely important in applications such as catalysis, biomedicine and environmental remediation. The small size of iron oxide nanoparticles can be used to stabilize oil-in-water Pickering emulsions due to their high energy of adsorption at the interface of oil droplets in water. The objective of this work is to investigate the effect of the primary particle characteristics and stabilizing agent chemistry on the stability of oil-in-water Pickering emulsions. Iron oxide nanoparticles were synthesized by the co-precipitation method using stoichiometric amounts of Fe2+ and Fe3+ salts. Sodium stearoyl lactylate (SSL), a Food and Drug Administration approved food additive, was used to functionalize the iron oxide nanoparticles. SSL is useful in the generation of fat-in-water emulsions due to its high hydrophilic-lipophilic balance and its bilayer-forming capacity. Generation of a monolayer or a bilayer coating on the nanoparticles was controlled through systematic changes in reagent concentrations. The coated particles were then characterized using various analytical techniques to determine their size, their crystal structure and surface functionalization. The capacity of these bilayer coated nanoparticles to stabilize oil-in-water emulsions under various salt concentrations and pH values was also systematically determined using various characterization techniques. This study successfully demonstrated the ability to synthesize iron oxide nanoparticles (20-40 nm) coated with SSL in order to generate stable Pickering emulsions that were pH-responsive and resistant to significant destabilization in a saline environment, thereby lending themselves to applications in advanced oil spill recovery and remediation.

  2. Biocompatibility of chitosan-coated iron oxide nanoparticles with osteoblast cells

    Directory of Open Access Journals (Sweden)

    Shi S

    2012-10-01

    Full Text Available Si-Feng Shi,1 Jing-Fu Jia,2 Xiao-Kui Guo,3 Ya-Ping Zhao,2 De-Sheng Chen,1 Yong-Yuan Guo,1 Tao Cheng,1 Xian-Long Zhang11Department of Orthopedic Surgery, Shanghai Sixth People’s Hospital, School of Medicine, 2School of Chemistry and Chemical Technology, 3Department of Medical Microbiology and Parasitology, School of Medicine, Shanghai Jiao Tong University Shanghai, ChinaBackground: Bone disorders (including osteoporosis, loosening of a prosthesis, and bone infections are of great concern to the medical community and are difficult to cure. Therapies are available to treat such diseases, but all have drawbacks and are not specifically targeted to the site of disease. Chitosan is widely used in the biomedical community, including for orthopedic applications. The aim of the present study was to coat chitosan onto iron oxide nanoparticles and to determine its effect on the proliferation and differentiation of osteoblasts.Methods: Nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, x-ray diffraction, zeta potential, and vibrating sample magnetometry. Uptake of nanoparticles by osteoblasts was studied by transmission electron microscopy and Prussian blue staining. Viability and proliferation of osteoblasts were measured in the presence of uncoated iron oxide magnetic nanoparticles or those coated with chitosan. Lactate dehydrogenase, alkaline phosphatase, total protein synthesis, and extracellular calcium deposition was studied in the presence of the nanoparticles.Results: Chitosan-coated iron oxide nanoparticles enhanced osteoblast proliferation, decreased cell membrane damage, and promoted cell differentiation, as indicated by an increase in alkaline phosphatase and extracellular calcium deposition. Chitosan-coated iron oxide nanoparticles showed good compatibility with osteoblasts.Conclusion: Further research is necessary to optimize magnetic nanoparticles for the treatment of bone disease

  3. Iron oxide nanotube layer fabricated with electrostatic anodization for heterogeneous Fenton like reaction

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jun-Won; Park, Jae-Woo, E-mail: jaewoopark@hanyang.ac.kr

    2014-05-01

    Highlights: • Iron oxide nanotube was newly fabricated with potentiostatic anodization of Fe{sup 0} foil. • Cyanide was oxidized more effectively with the iron oxide nanotube and H{sub 2}O{sub 2}, resulting in fast oxidation of cyanide and cyanate. • This nanotube of Fe{sub 2}O{sub 3} on Fe{sup 0} metal can replace conventional particulate iron catalysts in Fenton-like processes. - Abstract: Iron oxide nanotubes (INT) were fabricated with potentiostatic anodization of zero valent iron foil in 1 M Na{sub 2}SO{sub 4} containing 0.5 wt% NH{sub 4}F electrolyte, holding the potential at 20, 40, and 60 V for 20 min, respectively. Field emission scanning electron microscopy and X-ray diffractometry were used to evaluate the morphology and crystalline structure of the INT film. The potential of 40 V for 20 min was observed to be optimal to produce an optimal catalytic film. Cyanide dissolved in water was degraded through the Fenton-like reaction using the INT film with hydrogen peroxide (H{sub 2}O{sub 2}). In case of INT-40 V in the presence of H{sub 2}O{sub 2} 3%, the first-order rate constant was found to be 1.7 × 10{sup −2} min{sup −1}, and 1.2 × 10{sup −2} min{sup −1} with commercial hematite powder. Degradation of cyanide was much less with only H{sub 2}O{sub 2}. Therefore, this process proposed in this work can be an excellent alternative to traditional catalysts for Fenton-like reaction.

  4. Superparamagnetic iron oxide nanoparticles (SPIONs)-loaded Trojan microparticles for targeted aerosol delivery to the lung.

    Science.gov (United States)

    Tewes, Frederic; Ehrhardt, Carsten; Healy, Anne Marie

    2014-01-01

    Targeted aerosol delivery to specific regions of the lung may improve therapeutic efficiency and minimise unwanted side effects. Targeted delivery could potentially be achieved with porous microparticles loaded with superparamagnetic iron oxide nanoparticles (SPIONs)-in combination with a target-directed magnetic gradient field. The aim of this study was to formulate and evaluate the aerodynamic properties of SPIONs-loaded Trojan microparticles after delivery from a dry powder inhaler. Microparticles made of SPIONs, PEG and hydroxypropyl-β-cyclodextrin (HPβCD) were formulated by spray drying and characterised by various physicochemical methods. Aerodynamic properties were evaluated using a next generation cascade impactor (NGI), with or without a magnet positioned at stage 2. Mixing appropriate proportions of SPIONs, PEG and HPβCD allowed Trojan microparticle to be formulated. These particles had a median geometric diameter of 2.8±0.3μm and were shown to be sensitive to the magnetic field induced by a magnet having a maximum energy product of 413.8kJ/m(3). However, these particles, characterised by a mass median aerodynamic diameter (MMAD) of 10.2±2.0μm, were considered to be not inhalable. The poor aerodynamic properties resulted from aggregation of the particles. The addition of (NH4)2CO3 and magnesium stearate (MgST) to the formulation improved the aerodynamic properties of the Trojan particles and resulted in a MMAD of 2.2±0.8μm. In the presence of a magnetic field on stage 2 of the NGI, the amount of particles deposited at this stage increased 4-fold from 4.8±0.7% to 19.5±3.3%. These Trojan particles appeared highly sensitive to the magnetic field and their deposition on most of the stages of the NGI was changed in the presence compared to the absence of the magnet. If loaded with a pharmaceutical active ingredient, these particles may be useful for treating localised lung disease such as cancer nodules or bacterial infectious foci. Copyright

  5. Oligomerization of glycine and alanine catalyzed by iron oxides: implications for prebiotic chemistry.

    Science.gov (United States)

    Shanker, Uma; Bhushan, Brij; Bhattacharjee, G; Kamaluddin

    2012-02-01

    Iron oxide minerals are probable constituents of the sediments present in geothermal regions of the primitive earth. They might have adsorbed different organic monomers (amino acids, nucleotides etc.) and catalyzed polymerization processes leading to the formation of the first living cell. In the present work we tested the catalytic activity of three forms of iron oxides (Goethite, Akaganeite and Hematite) in the intermolecular condensation of each of the amino acids glycine and L-alanine. The effect of zinc oxide and titanium dioxide on the oligomerization has also been studied. Oligomerization studies were performed for 35 days at three different temperatures 50, 90 and 120°C without applying drying/wetting cycling. The products formed were characterized by HPLC and ESI-MS techniques. All three forms of iron oxides catalyzed peptide bond formation (23.2% of gly2 and 10.65% of ala2). The reaction was monitored every 7 days. Formation of peptides was observed to start after 7 days at 50°C. Maximum yield of peptides was found after 35 days at 90°C. Reaction at 120°C favors formation of diketopiperazine derivatives. It is also important to note that after 35 days of reaction, goethite produced dimer and trimer with the highest yield among the oxides tested. We suggest that the activity of goethite could probably be due to its high surface area and surface acidity.

  6. Effects of iron-aluminium oxides and organic carbon on aggregate stability of bauxite residues.

    Science.gov (United States)

    Zhu, Feng; Li, Yubing; Xue, Shengguo; Hartley, William; Wu, Hao

    2016-05-01

    In order to successfully establish vegetation on bauxite residue, properties such as aggregate structure and stability require improvement. Spontaneous plant colonization on the deposits in Central China over the last 20 years has revealed that natural processes may improve the physical condition of bauxite residues. Samples from three different stacking ages were selected to determine aggregate formation and stability and its relationship with iron-aluminium oxides and organic carbon. The residue aggregate particles became coarser in both dry and wet sieving processes. The mean weight diameter (MWD) and geometry mean diameter (GMD) increased significantly, and the proportion of aggregate destruction (PAD) decreased. Natural stacking processes could increase aggregate stability and erosion resistant of bauxite residues. Free iron oxides and amorphous aluminium oxides were the major forms in bauxite residues, but there was no significant correlation between the iron-aluminium oxides and aggregate stability. Aromatic-C, alkanes-C, aliphatic-C and alkenes-C were the major functional groups present in the residues. With increasing stacking age, total organic carbon content and aggregate-associated organic carbon both increased. Alkanes-C, aliphatic-C and alkenes-C increased and were mainly distributed in macro-aggregates, whereas aromatic-C was mainly distributed in aluminium oxides maybe more important for stability of micro-aggregates.

  7. Large-Scale Synthesis of Single-Crystalline Iron Oxide Magnetic Nanorings

    DEFF Research Database (Denmark)

    Jia, Chun-Jiang; Sun, Ling-Dong; Luo, Feng

    2008-01-01

    We present an innovative approach to the production of single-crystal iron oxide nanorings employing a solution-based route. Single-crystal hematite (alpha-Fe2O3) nanorings were synthesized using a double anion-assisted hydrothermal method (involving phosphate and sulfate ions), which can...... an intriguing three-dimensional magnetic configuration. This work provides an easily scaled-up method for preparing tailor-made iron oxide nanorings that could meet the demands of a variety of applications ranging from medicine to magnetoelectronics....... able to control the size, morphology, and surface architecture to produce a variety of three-dimensional hollow nanostructures. These can then be converted to magnetite (Fe3O4) and maghemite (gamma-Fe2O3) by a reduction or reduction-oxidation process while preserving the same morphology. The structures...

  8. Effect of magnesium ions on the initial oxidation stages of carbon steel

    International Nuclear Information System (INIS)

    Subramanian, H.; Subramanian, Veena; Rangarajan, S.; Narasimhan, S.V.; Velmurugan, S.

    2012-09-01

    corrosion of pearlite phase containing alternate band of α-Fe and carbide phases. For the film formed on pearlite phase in presence of Mg, the cross sectional profile showed more corrugations. The corrugations were a combined result of differential iron removal due to corrosion from the α-Fe phase in comparison to the cementite phase in pearlite and its subsequent coverage by oxide formation. In the absence of Mg, the corrosion was observed to be more in α-Fe phase of pearlite and the resultant oxide formed covered the corroded surface resulting in lesser corrugations. The roughness histograms obtained for both pearlite and ferrite regions indicated that the surface was rougher when magnesium was not added during the film formation. This study suggested that Mg influences/ modifies the oxidation of carbon steel right from its initial stages of corrosion and these factors in turn may influence the overall protectiveness of the oxide film with aging. (authors)

  9. Iron

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...... of transcription factors, activation of the mitochondrial apoptotic machinery or of other cell death mechanisms. The pro-inflammatory cytokine IL-1β facilitates divalent metal transporter 1 (DMT1)-induced β-cell iron uptake and consequently ROS formation and apoptosis, and we propose that this mechanism provides...

  10. Clearance of iron oxide particles in rat liver: effect of hydrated particle size and coating material on liver metabolism.

    Science.gov (United States)

    Briley-Saebo, Karen C; Johansson, Lars O; Hustvedt, Svein Olaf; Haldorsen, Anita G; Bjørnerud, Atle; Fayad, Zahi A; Ahlstrom, Haakan K

    2006-07-01

    We sought to evaluate the effect of the particle size and coating material of various iron oxide preparations on the rate of rat liver clearance. The following iron oxide formulations were used in this study: dextran-coated ferumoxide (size = 97 nm) and ferumoxtran-10 (size = 21 nm), carboxydextran-coated SHU555A (size = 69 nm) and fractionated SHU555A (size = 12 nm), and oxidized-starch coated materials either unformulated NC100150 (size = 15 nm) or formulated NC100150 injection (size = 12 nm). All formulations were administered to 165 rats at 2 dose levels. Quantitative liver R2* values were obtained during a 63-day time period. The concentration of iron oxide particles in the liver was determined by relaxometry, and these values were used to calculate the particle half-lives in the liver. After the administration of a high dose of iron oxide, the half-life of iron oxide particles in rat liver was 8 days for dextran-coated materials, 10 days for carboxydextran materials, 14 days for unformulated oxidized-starch, and 29 days for formulated oxidized-starch. The results of the study indicate that materials with similar coating but different sizes exhibited similar rates of liver clearance. It was, therefore, concluded that the coating material significantly influences the rate of iron oxide clearance in rat liver.

  11. Efficient MRI labeling of endothelial progenitor cells: design of thiolated surface stabilized superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Shahnaz, Gul; Kremser, Christian; Reinisch, Andreas; Vetter, Anja; Laffleur, Flavia; Rahmat, Deni; Iqbal, Javed; Dünnhaupt, Sarah; Salvenmoser, Willi; Tessadri, Richard; Griesser, Ulrich; Bernkop-Schnürch, Andreas

    2013-11-01

    The aim of this study was to design thiolated surface stabilized superparamagnetic iron oxide nanoparticles (TSS-SPIONs) for efficient internalization with high MRI sensitivity. TSS-SPIONs were developed by chelation between thiolated chitosan-thioglycolic acid (chitosan-TGA) hydrogel and iron ions (Fe(2+)/Fe(3+)). Likely, unmodified chitosan hydrogel SPIONs (UC-SPIONs) and uncoated SPIONs were used as control. Moreover, TSS-SPIONs were investigated regarding to their iron core size, hydrodynamic diameter, zeta potential, iron contents, molar relaxivities (r1 and r2), and cellular internalization. TSS-SPIONs demonstrated an iron oxide core diameter (crystallite size by XRD) of 3.1 ± 0.02 nm, a hydrodynamic diameter of 94 ± 20 nm, a zeta potential of +21 ± 5 mV, and an iron content of 3.6 ± 0.9 mg/mL. In addition, internalization of TSS-SPIONs into human endothelial progenitor cells (EPC) from umbilical cord blood was more than threefold and 17-fold higher in contrast to UC-SPIONs and SPIONs, respectively. With twofold lower incubation iron concentration of TSS-SPIONs, more than threefold higher internalization was achieved as compared to Resovist®. Also, cell viability of more than 90% was observed in the presence of TSS-SPIONs after 24h. The molar MR relaxivities (r2) value at 1.5 T was threefold higher than that of Resovist® and demonstrated that TSS-SPIONs have the potential as very effective T2 contrast-enhancement agent. According to these findings, TSS-SPIONs with efficient internalization, lower cytotoxicity, and high MRI sensitivity seem to be promising for cell tracking. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature.

    Science.gov (United States)

    Zhang, Lili; Yu, Xinxin; Hu, Hongrui; Li, Yang; Wu, Mingzai; Wang, Zhongzhu; Li, Guang; Sun, Zhaoqi; Chen, Changle

    2015-03-19

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4 · 7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures.

  13. Antibacterial activity of magnetic iron oxide nanoparticles synthesized by laser ablation in liquid

    International Nuclear Information System (INIS)

    Ismail, Raid A.; Sulaiman, Ghassan M.; Abdulrahman, Safa A.; Marzoog, Thorria R.

    2015-01-01

    In this study, (50–110 nm) magnetic iron oxide (α-Fe 2 O 3 ) nanoparticles were synthesized by pulsed laser ablation of iron target in dimethylformamide (DMF) and sodium dodecyl sulfate (SDS) solutions. The structural properties of the synthesized nanoparticles were investigated by using Fourier Transform Infrared (FT-IR) spectroscopy, UV–VIS absorption, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The effect of laser fluence on the characteristics of these nanoparticles was studied. Antibacterial activities of iron oxide nanoparticles were tested against Gram-positive; Staphylococcus aureus and Gram-negative; Escherichia coli, Pseudomonas aeruginosa and Serratia marcescens. The results showed a noteworthy inhibition on both bacterial strains. The preparation conditions were found to affect significantly the antibacterial activity of these nanoparticles. The synthesized magnetic nanoparticles were used to capture rapidly S. aureus bacteria under the magnetic field effect. - Highlights: • Synthesis magnetic iron oxide nanoparticles by pulsed laser ablation • Antibacterial activity against Gram-positive and Gram-negative bacteria • Captured magnetic nanoparticles by S. aureus bacteria under effect of magnetic field

  14. Antibacterial activity of magnetic iron oxide nanoparticles synthesized by laser ablation in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Raid A., E-mail: raidismail@yahoo.com [Laser Physics Division, Applied Science Department, University of Technology, Baghdad (Iraq); Sulaiman, Ghassan M. [Biotechnology Division, Applied Science Department, University of Technology, Baghdad (Iraq); Abdulrahman, Safa A. [Laser Physics Division, Applied Science Department, University of Technology, Baghdad (Iraq); Marzoog, Thorria R. [Biotechnology Division, Applied Science Department, University of Technology, Baghdad (Iraq)

    2015-08-01

    In this study, (50–110 nm) magnetic iron oxide (α-Fe{sub 2}O{sub 3}) nanoparticles were synthesized by pulsed laser ablation of iron target in dimethylformamide (DMF) and sodium dodecyl sulfate (SDS) solutions. The structural properties of the synthesized nanoparticles were investigated by using Fourier Transform Infrared (FT-IR) spectroscopy, UV–VIS absorption, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The effect of laser fluence on the characteristics of these nanoparticles was studied. Antibacterial activities of