Science.gov

Sample records for respiratory iron oxidation

  1. Enzymes of respiratory iron oxidation

    SciTech Connect

    Blake, R. II.

    1991-01-01

    This report focuses on the progress made in three areas of research concerned with enzymes involved in respiratory iron oxidation. The three areas are as follows: development of an improved procedure for the routine large scale culture of iron oxidizing chemolithotrophs based on the in-situ electrolysis of the soluble iron in the growth medium; to perform iron oxidation kinetic studies on whole cells using the oxygen electrode; and to identify, separate, purify, and characterize the individual cellular components.

  2. Enzymes of respiratory iron oxidation

    SciTech Connect

    Blake, R. II.

    1992-01-01

    This report describes experimental progress in characterizing and identifying redox proteins in a number of iron-oxidizing bacteria. Sections of the paper are entitled (1) In Situ electrolysis was explored to achieve enhanced yields of iron-oxidizing bacteria, (2)Structure/function studies were performed on redox-active biomolecules from Thiobacillus ferrooxidans, (3) Novel redox-active biomolecules were demonstrated in other iron autotrophs, and (4) New probes of metalloprotein electron-transfer reactions were synthesized and characterized.

  3. Enzymes of respiratory iron oxidation. Progress report, March 1990--November 1991

    SciTech Connect

    Blake, R. II

    1991-12-31

    This report focuses on the progress made in three areas of research concerned with enzymes involved in respiratory iron oxidation. The three areas are as follows: development of an improved procedure for the routine large scale culture of iron oxidizing chemolithotrophs based on the in-situ electrolysis of the soluble iron in the growth medium; to perform iron oxidation kinetic studies on whole cells using the oxygen electrode; and to identify, separate, purify, and characterize the individual cellular components.

  4. Respiratory interactions of soil bacteria with (semi)conductive iron-oxide minerals.

    PubMed

    Kato, Souichiro; Nakamura, Ryuhei; Kai, Fumiyoshi; Watanabe, Kazuya; Hashimoto, Kazuhito

    2010-12-01

    Pure-culture studies have shown that dissimilatory metal-reducing bacteria are able to utilize iron-oxide nanoparticles as electron conduits for reducing distant terminal acceptors; however, the ecological relevance of such energy metabolism is poorly understood. Here, soil microbial communities were grown in electrochemical cells with acetate as the electron donor and electrodes (poised at 0.2 V versus Ag/AgCl) as the electron acceptors in the presence and absence of iron-oxide nanoparticles, and respiratory current generation and community structures were analysed. Irrespective of the iron-oxide species (hematite, magnetite or ferrihydrite), the supplementation with iron-oxide minerals resulted in large increases (over 30-fold) in current, while only a moderate increase (∼10-fold) was observed in the presence of soluble ferric/ferrous irons. During the current generation, insulative ferrihydrite was transformed into semiconductive goethite. Clone-library analyses of 16S rRNA gene fragments PCR-amplified from the soil microbial communities revealed that iron-oxide supplementation facilitated the occurrence of Geobacter species affiliated with subsurface clades 1 and 2. We suggest that subsurface-clade Geobacter species preferentially thrive in soil by utilizing (semi)conductive iron oxides for their respiration.

  5. Enzymes of respiratory iron oxidation. Progress report, March 1990--June 1992

    SciTech Connect

    Blake, R. II

    1992-12-31

    This report describes experimental progress in characterizing and identifying redox proteins in a number of iron-oxidizing bacteria. Sections of the paper are entitled (1) In Situ electrolysis was explored to achieve enhanced yields of iron-oxidizing bacteria, (2)Structure/function studies were performed on redox-active biomolecules from Thiobacillus ferrooxidans, (3) Novel redox-active biomolecules were demonstrated in other iron autotrophs, and (4) New probes of metalloprotein electron-transfer reactions were synthesized and characterized.

  6. Iron Oxides

    SciTech Connect

    Qafoku, Nikolla; Amonette, James E.

    2016-09-19

    Abstract: Fe oxides are common clay-sized oxide, oxyhydroxide and hydroxide soil minerals. They are compounds of Fe, O, and H that have structures based on close-packed arrays of O. The octahedral and tetrahedral cavities within these arrays are filled with either Fe3+ or Fe2+ to form Fe(O/OH)6, FeO6, or FeO4 structural units. All of the naturally occurring Fe oxide minerals usually undergo some degree of isomorphous substitution of other metal ions for Fe in their structures. Relatively simple techniques may be used to identify Fe oxides in the field based on their typical colors and magnetic properties. In the laboratory, a variety of instrumental techniques can be used to confirm phase identity and to quantify amount. Of these, X-ray diffraction, infrared spectroscopy, electron microscopy, thermal analysis, and Mössbauer spectroscopy are the most commonly used techniques. As oxides, the functional groups on their surfaces may have positive, negative, or no charge depending on pH and on the concentration and nature of other ions in the contact solution. A net positive surface charge usually is observed in soils because Fe oxides have a point-of-zero-charge in the neutral or slightly basic pHs. The functional groups on the surface form complexes with cations and anions from the aqueous phase. Their sorption and electron-buffering properties significantly affect the geochemical cycles of almost all elements having agronomic or environmental significance.

  7. Malfunctioning of the Iron–Sulfur Cluster Assembly Machinery in Saccharomyces cerevisiae Produces Oxidative Stress via an Iron-Dependent Mechanism, Causing Dysfunction in Respiratory Complexes

    PubMed Central

    Gomez, Mauricio; Pérez-Gallardo, Rocío V.; Sánchez, Luis A.; Díaz-Pérez, Alma L.; Cortés-Rojo, Christian; Meza Carmen, Victor; Saavedra-Molina, Alfredo; Lara-Romero, Javier; Jiménez-Sandoval, Sergio; Rodríguez, Francisco; Rodríguez-Zavala, José S.; Campos-García, Jesús

    2014-01-01

    Biogenesis and recycling of iron–sulfur (Fe–S) clusters play important roles in the iron homeostasis mechanisms involved in mitochondrial function. In Saccharomyces cerevisiae, the Fe–S clusters are assembled into apoproteins by the iron–sulfur cluster machinery (ISC). The aim of the present study was to determine the effects of ISC gene deletion and consequent iron release under oxidative stress conditions on mitochondrial functionality in S. cerevisiae. Reactive oxygen species (ROS) generation, caused by H2O2, menadione, or ethanol, was associated with a loss of iron homeostasis and exacerbated by ISC system dysfunction. ISC mutants showed increased free Fe2+ content, exacerbated by ROS-inducers, causing an increase in ROS, which was decreased by the addition of an iron chelator. Our study suggests that the increment in free Fe2+ associated with ROS generation may have originated from mitochondria, probably Fe–S cluster proteins, under both normal and oxidative stress conditions, suggesting that Fe–S cluster anabolism is affected. Raman spectroscopy analysis and immunoblotting indicated that in mitochondria from SSQ1 and ISA1 mutants, the content of [Fe–S] centers was decreased, as was formation of Rieske protein-dependent supercomplex III2IV2, but this was not observed in the iron-deficient ATX1 and MRS4 mutants. In addition, the activity of complexes II and IV from the electron transport chain (ETC) was impaired or totally abolished in SSQ1 and ISA1 mutants. These results confirm that the ISC system plays important roles in iron homeostasis, ROS stress, and in assembly of supercomplexes III2IV2 and III2IV1, thus affecting the functionality of the respiratory chain. PMID:25356756

  8. The iron-oxidizing proteobacteria.

    PubMed

    Hedrich, Sabrina; Schlömann, Michael; Johnson, D Barrie

    2011-06-01

    The 'iron bacteria' are a collection of morphologically and phylogenetically heterogeneous prokaryotes. They include some of the first micro-organisms to be observed and described, and continue to be the subject of a considerable body of fundamental and applied microbiological research. While species of iron-oxidizing bacteria can be found in many different phyla, most are affiliated with the Proteobacteria. The latter can be subdivided into four main physiological groups: (i) acidophilic, aerobic iron oxidizers; (ii) neutrophilic, aerobic iron oxidizers; (iii) neutrophilic, anaerobic (nitrate-dependent) iron oxidizers; and (iv) anaerobic photosynthetic iron oxidizers. Some species (mostly acidophiles) can reduce ferric iron as well as oxidize ferrous iron, depending on prevailing environmental conditions. This review describes what is currently known about the phylogenetic and physiological diversity of the iron-oxidizing proteobacteria, their significance in the environment (on the global and micro scales), and their increasing importance in biotechnology.

  9. Iron oxide surfaces

    NASA Astrophysics Data System (ADS)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  10. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 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...

  11. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 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...

  12. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 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...

  13. Role of iron in the pathogenesis of respiratory disease.

    PubMed

    Ali, Md Khadem; Kim, Richard Y; Karim, Rafia; Mayall, Jemma R; Martin, Kristy L; Shahandeh, Ali; Abbasian, Firouz; Starkey, Malcolm R; Loustaud-Ratti, Veronique; Johnstone, Daniel; Milward, Elizabeth A; Hansbro, Philip M; Horvat, Jay C

    2017-07-01

    Iron is essential for many biological processes, however, too much or too little iron can result in a wide variety of pathological consequences, depending on the organ system, tissue or cell type affected. In order to reduce pathogenesis, iron levels are tightly controlled in throughout the body by regulatory systems that control iron absorption, systemic transport and cellular uptake and storage. Altered iron levels and/or dysregulated homeostasis have been associated with several lung diseases, including chronic obstructive pulmonary disease, lung cancer, cystic fibrosis, idiopathic pulmonary fibrosis and asthma. However, the mechanisms that underpin these associations and whether iron plays a key role in the pathogenesis of lung disease are yet to be fully elucidated. Furthermore, in order to survive and replicate, pathogenic micro-organisms have evolved strategies to source host iron, including freeing iron from cells and proteins that store and transport iron. To counter these microbial strategies, mammals have evolved immune-mediated defence mechanisms that reduce iron availability to pathogens. This interplay between iron, infection and immunity has important ramifications for the pathogenesis and management of human respiratory infections and diseases. An increased understanding of the role that iron plays in the pathogenesis of lung disease and respiratory infections may help inform novel therapeutic strategies. Here we review the clinical and experimental evidence that highlights the potential importance of iron in respiratory diseases and infections. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Water oxidation: High five iron

    NASA Astrophysics Data System (ADS)

    Lloret-Fillol, Julio; Costas, Miquel

    2016-03-01

    The oxidation of water is essential to the sustainable production of fuels using sunlight or electricity, but designing active, stable and earth-abundant catalysts for the reaction is challenging. Now, a complex containing five iron atoms is shown to efficiently oxidize water by mimicking key features of the oxygen-evolving complex in green plants.

  15. 46 CFR 148.275 - Iron oxide, spent; iron sponge, spent.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Iron oxide, spent; iron sponge, spent. 148.275 Section... § 148.275 Iron oxide, spent; iron sponge, spent. (a) Before spent iron oxide or spent iron sponge is... been cooled and weathered for at least eight weeks. (b) Both spent iron oxide and spent iron sponge may...

  16. 46 CFR 148.275 - Iron oxide, spent; iron sponge, spent.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Iron oxide, spent; iron sponge, spent. 148.275 Section... § 148.275 Iron oxide, spent; iron sponge, spent. (a) Before spent iron oxide or spent iron sponge is... been cooled and weathered for at least eight weeks. (b) Both spent iron oxide and spent iron sponge may...

  17. 46 CFR 148.275 - Iron oxide, spent; iron sponge, spent.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Iron oxide, spent; iron sponge, spent. 148.275 Section... § 148.275 Iron oxide, spent; iron sponge, spent. (a) Before spent iron oxide or spent iron sponge is... been cooled and weathered for at least eight weeks. (b) Both spent iron oxide and spent iron sponge may...

  18. 46 CFR 148.275 - Iron oxide, spent; iron sponge, spent.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Iron oxide, spent; iron sponge, spent. 148.275 Section... § 148.275 Iron oxide, spent; iron sponge, spent. (a) Before spent iron oxide or spent iron sponge is... been cooled and weathered for at least eight weeks. (b) Both spent iron oxide and spent iron sponge may...

  19. Mössbauer spectroscopy on respiratory complex I: the iron-sulfur cluster ensemble in the NADH-reduced enzyme is partially oxidized.

    PubMed

    Bridges, Hannah R; Bill, Eckhard; Hirst, Judy

    2012-01-10

    In mitochondria, complex I (NADH:quinone oxidoreductase) couples electron transfer to proton translocation across an energy-transducing membrane. It contains a flavin mononucleotide to oxidize NADH, and an unusually long series of iron-sulfur (FeS) clusters that transfer the electrons to quinone. Understanding electron transfer in complex I requires spectroscopic and structural data to be combined to reveal the properties of individual clusters and of the ensemble. EPR studies on complex I from Bos taurus have established that five clusters (positions 1, 2, 3, 5, and 7 along the seven-cluster chain extending from the flavin) are (at least partially) reduced by NADH. The other three clusters, positions 4 and 6 plus a cluster on the other side of the flavin, are not observed in EPR spectra from the NADH-reduced enzyme: they may remain oxidized, have unusual or coupled spin states, or their EPR signals may be too fast relaxing. Here, we use Mössbauer spectroscopy on (57)Fe-labeled complex I from the mitochondria of Yarrowia lipolytica to show that the cluster ensemble is only partially reduced in the NADH-reduced enzyme. The three EPR-silent clusters are oxidized, and only the terminal 4Fe cluster (position 7) is fully reduced. Together with the EPR analyses, our results reveal an alternating profile of higher and lower potential clusters between the two active sites in complex I; they are not consistent with the consensus picture of a set of isopotential clusters. The implications for intramolecular electron transfer along the extended chain of cofactors in complex I are discussed.

  20. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 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...

  1. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2010 CFR

    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...

  2. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 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...

  3. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 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...

  4. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 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...

  5. Iron oxidation by Thiobacillus ferrooxidans

    SciTech Connect

    Kang, Sunki; Sproull, R.D.

    1991-12-31

    Several investigators have shown that microorganisms are involved in many naturally occurring oxidation processes. At present, microbial leaching, which is the solubilization of metals catalyzed by microorganisms, is widely used commercially to produce copper, and to a lesser extent uranium, from low-grade mining wastes. Microbial leaching can also be used as a pretreatment step in the mining of precious metals, such as gold and silver. In this application, the solubilization of pyrite makes the precious metals more accessible for cyanide leaching. Because ferrous iron oxidation is such an important reaction in microbial leaching operations, this study was undertaken to examine factors affecting the rate of ferrous iron oxidation in the presence of T. ferrooxidans.

  6. High temperature oxidation of iron-iron oxide core-shell nanowires composed of iron nanoparticles.

    PubMed

    Krajewski, M; Brzozka, K; Lin, W S; Lin, H M; Tokarczyk, M; Borysiuk, J; Kowalski, G; Wasik, D

    2016-02-07

    This work describes an oxidation process of iron-iron oxide core-shell nanowires at temperatures between 100 °C and 800 °C. The studied nanomaterial was synthesized through a simple chemical reduction of iron trichloride in an external magnetic field under a constant flow of argon. The electron microscopy investigations allowed determining that the as-prepared nanowires were composed of self-assembled iron nanoparticles which were covered by a 3 nm thick oxide shell and separated from each other by a thin interface layer. Both these layers exhibited an amorphous or highly-disordered character which was traced by means of transmission electron microscopy and Mössbauer spectroscopy. The thermal oxidation was carried out under a constant flow of argon which contained the traces of oxygen. The first stage of process was related to slow transformations of amorphous Fe and amorphous iron oxides into crystalline phases and disappearance of interfaces between iron nanoparticles forming the studied nanomaterial (range: 25-300 °C). After that, the crystalline iron core and iron oxide shell became oxidized and signals for different compositions of iron oxide sheath were observed (range: 300-800 °C) using X-ray diffraction, Raman spectroscopy and Mössbauer spectroscopy. According to the thermal gravimetric analysis, the nanowires heated up to 800 °C under argon atmosphere gained 37% of mass with respect to their initial weight. The structure of the studied nanomaterial oxidized at 800 °C was mainly composed of α-Fe2O3 (∼ 93%). Moreover, iron nanowires treated above 600 °C lost their wire-like shape due to their shrinkage and collapse caused by the void coalescence.

  7. Iron, Oxidative Stress and Gestational Diabetes

    PubMed Central

    Zhuang, Taifeng; Han, Huijun; Yang, Zhenyu

    2014-01-01

    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. PMID:25255832

  8. IRON AND IRON-RELATED PROTEINS IN THE LOWER RESPIRATORY TRACT OF ARDS PATIENTS

    EPA Science Inventory

    OBJECTIVE: An increased oxidative stress in the lower respiratory tract of individuals with acute respiratory distress syndrome is considered to be one mechanism of lung injury in these patients. Cell and tissue damage resulting from an oxidative stress can ultimately be the cons...

  9. IRON AND IRON-RELATED PROTEINS IN THE LOWER RESPIRATORY TRACT OF ARDS PATIENTS

    EPA Science Inventory

    OBJECTIVE: An increased oxidative stress in the lower respiratory tract of individuals with acute respiratory distress syndrome is considered to be one mechanism of lung injury in these patients. Cell and tissue damage resulting from an oxidative stress can ultimately be the cons...

  10. Indium Sorption to Iron Oxides

    NASA Astrophysics Data System (ADS)

    White, S. J.; Sacco, S. A.; Hemond, H.; Hussain, F. A.; Runkel, R. L.; Walton-Day, K. E.; Kimball, B. A.; Shine, J. P.

    2014-12-01

    Indium is an increasingly important metal in semiconductors and electronics, and its use is growing rapidly as a semiconductive coating (as indium tin oxide) for liquid crystal displays (LCDs) and flat panel displays. It also has uses in important energy technologies such as light emitting diodes (LEDs) and photovoltaic cells. Despite its rapid increase in use, very little is known about the environmental behavior of indium, and concerns are being raised over the potential health effects of this emerging metal contaminant. One source of indium to the environment is acid mine drainage from the mining of lead, zinc, and copper sulfides. In our previous studies of a stream in Colorado influenced by acid mine drainage from lead and zinc mining activities, indium concentrations were found to be 10,000 times those found in uncontaminated rivers. However, the speciation and mobility of indium could not be reliably modeled because sorption constants to environmental sorbents have not been determined. In this study, we generate sorption constants for indium to ferrihydrite in the laboratory over a range of pHs, sorbent to sorbate ratios, and ionic strengths. Ferrihydrite is one of the most important sorbents in natural systems, and sorption to amorphous iron oxides such as ferrihydrite is thought to be one of the main removal mechanisms of metals from the dissolved phase in aqueous environments. Because of its relatively low solubility, we also find that indium hydroxide precipitation can dominate indium's partitioning at micromolar concentrations of indium. This precipitation may be important in describing indium's behavior in our study stream in Colorado, where modeling sorption to iron-oxides does not explain the complete removal of indium from the dissolved phase when the pH of the system is artificially raised to above 8. This study contributes much-needed data about indium's aqueous behavior, in order to better understand its fate, transport, and impacts in the

  11. 21 CFR 186.1374 - Iron oxides.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) are undefined mixtures of iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron (III) oxide (CAS Reg. No. 1309-37-1, red-brown to black trigonal crystals). (b) In accordance with § 186.1(b...

  12. 21 CFR 186.1374 - Iron oxides.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) are undefined mixtures of iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron (III) oxide (CAS Reg. No. 1309-37-1, red-brown to black trigonal crystals). (b) In accordance with § 186.1(b...

  13. 21 CFR 186.1374 - Iron oxides.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) are undefined mixtures of iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron (III) oxide (CAS Reg. No. 1309-37-1, red-brown to black trigonal crystals). (b) In accordance with § 186.1(b...

  14. 21 CFR 186.1374 - Iron oxides.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) are undefined mixtures of iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron (III) oxide (CAS Reg. No. 1309-37-1, red-brown to black trigonal crystals). (b) In accordance with § 186.1(b...

  15. 21 CFR 186.1374 - Iron oxides.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron (III) oxide (CAS Reg. No. 1309-37-1, red-brown to black trigonal crystals). (b) In accordance with § 186.1(b)(1), the ingredient is...

  16. Tannin biosynthesis of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Herrera-Becerra, R.; Rius, J. L.; Zorrilla, C.

    2010-08-01

    In this work, iron oxide nanoparticles synthesized with gallic acid and tannic acid are characterized using High-Resolution Transmission Electron Microscopy (HRTEM). Its size, form, and structure are compared with nanoparticles obtained previously using alfalfa biomass in order to find a simpler, consistent, and environmentally friendly method in the production of iron oxide nanoparticles.

  17. Enzymatic iron oxidation by Leptothrix discophora: identification of an iron-oxidizing protein.

    PubMed Central

    Corstjens, P L; de Vrind, J P; Westbroek, P; de Vrind-de Jong, E W

    1992-01-01

    An iron-oxidizing factor was identified in the spent culture medium of the iron- and manganese-oxidizing bacterial strain Leptothrix discophora SS-1. It appeared to be a protein, with an apparent molecular weight of approximately 150,000. Its activity could be demonstrated after fractionation of the spent medium by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A spontaneous mutant of L. discophora SS-1 was isolated which excreted neither manganese- nor iron-oxidizing activity, whereas excretion of other proteins seemed to be unaffected. Although the excretion of both metal-oxidizing factors was probably linked, the difference in other properties suggests that manganese and iron oxidation represent two different pathways. With a dot-blot assay, it was established that different bacterial species have different metal-oxidizing capacities. Whereas L. discophora oxidized both iron and manganese, Sphaerotilus natans oxidized only iron and two Pseudomonas spp. oxidized only manganese. Images PMID:1610168

  18. Facile and Sustainable Synthesis of Shaped Iron Oxide Nanoparticles: Effect of Iron Precursor Salts on the Shapes of Iron Oxides

    PubMed Central

    Sayed, Farheen N.; Polshettiwar, Vivek

    2015-01-01

    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. PMID:25939969

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

    PubMed

    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.

  20. Nanosized Iron Oxide Colloids Strongly Enhance Microbial Iron Reduction▿ †

    PubMed Central

    Bosch, Julian; Heister, Katja; Hofmann, Thilo; Meckenstock, Rainer U.

    2010-01-01

    Microbial iron reduction is considered to be a significant subsurface process. The rate-limiting bioavailability of the insoluble iron oxyhydroxides, however, is a topic for debate. Surface area and mineral structure are recognized as crucial parameters for microbial reduction rates of bulk, macroaggregate iron minerals. However, a significant fraction of iron oxide minerals in the subsurface is supposed to be present as nanosized colloids. We therefore studied the role of colloidal iron oxides in microbial iron reduction. In batch growth experiments with Geobacter sulfurreducens, colloids of ferrihydrite (hydrodynamic diameter, 336 nm), hematite (123 nm), goethite (157 nm), and akaganeite (64 nm) were added as electron acceptors. The colloidal iron oxides were reduced up to 2 orders of magnitude more rapidly (up to 1,255 pmol h−1 cell−1) than bulk macroaggregates of the same iron phases (6 to 70 pmol h−1 cell−1). The increased reactivity was not only due to the large surface areas of the colloidal aggregates but also was due to a higher reactivity per unit surface. We hypothesize that this can be attributed to the high bioavailability of the nanosized aggregates and their colloidal suspension. Furthermore, a strong enhancement of reduction rates of bulk ferrihydrite was observed when nanosized ferrihydrite aggregates were added. PMID:19915036

  1. Platinum Attachments on Iron Oxide Nanoparticle Surfaces

    SciTech Connect

    Palchoudhury, Soubantika; Xu, Yaolin; An, Wei; Turner, C. H.; Bao, Yuping

    2010-04-30

    Platinum nanoparticles supported on metal oxide surfaces have shown great potential as heterogeneous catalysts to accelerate electrochemical processes, such as the oxygen reduction reaction in fuel cells. Recently, the use of magnetic supports has become a promising research topic for easy separation and recovery of catalysts using magnets, such as Pt nanoparticles supported on iron oxide nanoparticles. The attachment of Pt on iron oxide nanoparticles is limited by the wetting ability of the Pt (metal) on ceramic surfaces. A study of Pt nanoparticle attachment on iron oxide nanoparticle surfaces in an organic solvent is reported, which addresses the factors that promote or inhibit such attachment. It was discovered that the Pt attachment strongly depends on the capping molecules of the iron oxide seeds and the reaction temperature. For example, the attachment of Pt nanoparticles on oleic acid coated iron oxide nanoparticles was very challenging, because of the strong binding between the carboxylic groups and iron oxide surfaces. In contrast, when nanoparticles are coated with oleic acid/tri-n-octylphosphine oxide or oleic acid/oleylamine, a significant increase in Pt attachment was observed. Electronic structure calculations were then applied to estimate the binding energies between the capping molecules and iron ions, and the modeling results strongly support the experimental observations.

  2. When Density Functional Approximations Meet Iron Oxides.

    PubMed

    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-Fe2O3, Fe3O4, 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.

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

    PubMed Central

    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

  4. On the formation of iron(III) oxides via oxidation of iron(II)

    SciTech Connect

    Bongiovanni, R.; Pelizzetti, E.; Borgarello, E.; Meisel, D.

    1994-09-01

    Formation of iron oxides in aqueous salt solutions is reviewed. The discussion is focused on the oxidation of iron(II) and the following hydrolysis process that leads to the formation of a solid phase from homogeneous solutions. Results from our own studies on the kinetics of the oxidation reactions and the ensuing growth processes are presented.

  5. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron..., including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing practice...

  6. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron..., including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing practice...

  7. Water soluble dendronized iron oxide nanoparticles.

    PubMed

    Daou, T J; Pourroy, G; Greneche, J M; Bertin, A; Felder-Flesch, D; Begin-Colin, S

    2009-06-21

    The grafting of pegylated dendrons on 9(2) nm and 39(5) nm iron oxide nanoparticles in water, through a phosphonate group as coupling agent has been successfully achieved and its mechanism investigated, with a view to produce biocompatible magnetic nano-objects for biomedical applications. Grafting has been demonstrated to occur by interaction of negatively charged phosphonate groups with positively charged groups and hydroxyl at the iron oxide surface. The isoelectric point of the suspension of dendronized iron oxide nanoparticles is shifted towards lower pH as the amount of dendron increases. It reaches 4.7 for the higher grafting rate and for both particle size. Thus, the grafting of molecules using a phosphonate group allows stabilizing electrostatically the suspensions at physiological pH, a prerequisite for biomedical applications. Moreover the grafting step has been shown to preserve the magnetic properties of iron oxide nanoparticles due to super-super exchange interactions through the phosphonate group.

  8. Ultrasound assisted phytosynthesis of iron oxide nanoparticle.

    PubMed

    Sathya, K; Saravanathamizhan, R; Baskar, G

    2017-11-01

    The present work deals with the ultrasound assisted green synthesis of iron oxide nano particle using Coriandrum sativum leaf extract as a reducing agent. The synthesized iron oxide nanoparticle was confirmed by UV spectra. The characterization was done to know more about morphology and size of the particle by SEM analysis which shows spherical particles with size ranging from 20 to 90nm. The antimicrobial activity of the leaf extract and the synthesized nanoparticles was studied against the pathogens Micrococcus luteus, Staphylococcus aureus and Aspergillus niger. The ultrasound assisted iron oxide nanoparticle shows higher scavenging activity and antimicrobial activity compared with iron oxide nanoparticle synthesized by magnetic stirrer and Coriandrum sativum leaf extract. Copyright © 2017. Published by Elsevier B.V.

  9. [Anemia and iron deficiency in children with chronic respiratory diseases].

    PubMed

    Barja, Salesa; Capo, Eduardo; Briceño, Lilian; Jakubson, Leticia; Méndez, Mireya; Becker, Ana

    2013-01-01

    Children with chronic respiratory disease (CRD) are at increased risk of iron deficiency and anemia, which is under-diagnosed. To describe the iron (Fe) status in children with CRD and to evaluate the effects of its prophylactic indication. Prospective study of children with CRD and adequate Fe intake in the diet. At baseline we measured hemogram, C-reactive protein and Fe profile. Subsequently, those with normal plasma hemoglobin (Hb) were not supplemented with Fe (Group A) and those with iron deficiency anemia or at risk of developing it (group B) were supplemented. We evaluated them 3 months later and, after supplementing all, at 4th month. Of 40 patients, median 30 months old (0.5 to 178), 60% were male, 80% eutrophic. Ventilation or oxygen were required in 45%. Diagnoses: 50% Chronic Lung Damage, 17.5% airway diseases, 10% Bronchopulmonary Dysplasia, 7.5% Cystic Fibrosis and 13.5% other. At baseline 20% were anemic (mostly ferropenic) and 12.5% had an abnormal iron profile. At all, 25 children completed the study: in group A, serum ferritin decreased to 3(th) month (-22.9 ± 30) and incremented to 4(th)month (+12.8 ± 26) μg/L (p = 0.013), without difference in Hb. Group B had a rise in Hb (91 ± 12 to 102 ± 12% of the mean for age, p = 0.04). Anemia and ferropenia are frequent in children with CRD. Decrease of their iron reserves can be prevented if they are supplemented. We suggest monitoring properly and treating early or supplement them prophylactically. Copyright © AULA MEDICA EDICIONES 2013. Published by AULA MEDICA. All rights reserved.

  10. The Irony of Iron - Biogenic Iron Oxides as an Iron Source to the Ocean.

    PubMed

    Emerson, David

    2015-01-01

    Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe) to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidizing bacteria (FeOB) that live by oxidizing iron and producing biogenic iron oxides as waste products. The presence and ubiquity of FeOB both at hydrothermal systems and in sediments is only beginning to be appreciated. The biogenic oxides they produce have unique properties that could contribute significantly to the dynamics of dFe in the ocean. Changes in the physical and chemical characteristics of the ocean due to climate change and ocean acidification will undoubtedly impact the microbial iron cycle. A better understanding of the contemporary role of microbes in the iron cycle will help in predicting how these changes could ultimately influence marine primary productivity.

  11. The Irony of Iron – Biogenic Iron Oxides as an Iron Source to the Ocean

    PubMed Central

    Emerson, David

    2016-01-01

    Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe) to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidizing bacteria (FeOB) that live by oxidizing iron and producing biogenic iron oxides as waste products. The presence and ubiquity of FeOB both at hydrothermal systems and in sediments is only beginning to be appreciated. The biogenic oxides they produce have unique properties that could contribute significantly to the dynamics of dFe in the ocean. Changes in the physical and chemical characteristics of the ocean due to climate change and ocean acidification will undoubtedly impact the microbial iron cycle. A better understanding of the contemporary role of microbes in the iron cycle will help in predicting how these changes could ultimately influence marine primary productivity. PMID:26779157

  12. Exploring Microbial Iron Oxidation in Wetland Soils

    NASA Astrophysics Data System (ADS)

    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

  13. Thermodynamic constraints on microbial iron oxide reduction

    NASA Astrophysics Data System (ADS)

    Bonneville, S.; Behrends, T.; Haese, R.; van Cappellen, P.

    2003-04-01

    Iron oxides are ubiquitous reactive constituents of soils, sediments and aquifers. They exhibit large surface areas which bind trace metals, nutrients and organic molecules. Under suboxic conditions, iron oxides can reductively dissolve via several abiotic and microbial pathways. In particular, they serve as terminal electron acceptors for the oxidation of organic matter by iron reducing bacteria. The aim of our study was to determine the thermodynamic energy yields of dissimilatory iron reduction for different Fe(III) substrates. We used the facultative anaerobic gram-positive bacterium Shewanella putrefaciens as model iron reducing bacterium, with ferrihydrite, hematite, goethite or Fe(III)-salicylate as electron acceptor, and lactate as electron donor. Experiments were conducted in an anaerobic pH-stat batch reactor, equipped with a polarographic electrode to monitor in situ the dissolved ferrous iron activity. The stoichiometry of total Fe(II) production and acid consumption during the experiments indicated that lactate was oxidized to acetate. From the Fe(II) activity and redox potential measurements, free energy yields were calculated for Fe(III) reduction coupled to lactate oxidation. The results showed that the redox potential of the overall reaction was poised by equilibrium between the Fe(III)-substrate and aqueous Fe(II). Hence, the energy yields decreased in the order ferrihydrite > Fe(III)-salicylate > hematite > goethite. Accumulation of Fe(II) in solution only caused small decreases in the energy yields over the course of the experiments. Cessation of iron reduction, which was observed in all experiments, was therefore not due to thermodynamic limitation, but more likely reflected the decline in cell level of activity.

  14. Metal ion binding to iron oxides

    NASA Astrophysics Data System (ADS)

    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.

  15. Iron oxide magnetic nanoparticles: A short review

    NASA Astrophysics Data System (ADS)

    Hasany, S. F.; Rehman, A.; Jose, R.; Ahmed, I.

    2012-11-01

    Magnetic nanoparticles have been enjoying great importance and wide scale applications during the last two decades due to their specific characteristics and applications. Iron oxide magnetic nanoparticles with appropriate surface chemistry have been implied in numerous applications such as biomedicine and cancer therapy, catalysis and in magnetic separation techniques. This review summarizes recent commercial, industrial and bio-engineering applications and brief study of the methods for the preparation of iron oxide magnetic nanoparticles with a control over the size, morphology and the magnetic properties. Some future applications of microwave irradiation for magnetic particle synthesis are also addressed.

  16. Iron oxides in human spleen.

    PubMed

    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. Carbon monoxide promotes respiratory hemoproteins iron reduction using peroxides as electron donors.

    PubMed

    Sher, Elena A; Shaklai, Mati; Shaklai, Nurith

    2012-01-01

    The physiological role of the respiratory hemoproteins (RH), hemoglobin and myoglobin, is to deliver O(2) via its binding to their ferrous (Fe(II)) heme-iron. Under variety of pathological conditions RH proteins leak to blood plasma and oxidized to ferric (Fe(III), met) forms becoming the source of oxidative vascular damage. However, recent studies have indicated that both metRH and peroxides induce Heme Oxygenase (HO) enzyme producing carbon monoxide (CO). The gas has an extremely high affinity for the ferrous heme-iron and is known to reduce ferric hemoproteins in the presence of suitable electron donors. We hypothesized that under in vivo plasma conditions, peroxides at low concentration can assist the reduction of metRH in presence of CO. The effect of CO on interaction of metRH with hydrophilic or hydrophobic peroxides was analyzed by following Soret and visible light absorption changes in reaction mixtures. It was found that under anaerobic conditions and low concentrations of RH and peroxides mimicking plasma conditions, peroxides served as electron donors and RH were reduced to their ferrous carboxy forms. The reaction rates were dependent on CO as well as peroxide concentrations. These results demonstrate that oxidative activity of acellular ferric RH and peroxides may be amended by CO turning on the reducing potential of peroxides and facilitating the formation of redox-inactive carboxyRH. Our data suggest the possible role of HO/CO in protection of vascular system from oxidative damage.

  18. Carbon Monoxide Promotes Respiratory Hemoproteins Iron Reduction Using Peroxides as Electron Donors

    PubMed Central

    Sher, Elena A.; Shaklai, Mati; Shaklai, Nurith

    2012-01-01

    The physiological role of the respiratory hemoproteins (RH), hemoglobin and myoglobin, is to deliver O2 via its binding to their ferrous (FeII) heme-iron. Under variety of pathological conditions RH proteins leak to blood plasma and oxidized to ferric (FeIII, met) forms becoming the source of oxidative vascular damage. However, recent studies have indicated that both metRH and peroxides induce Heme Oxygenase (HO) enzyme producing carbon monoxide (CO). The gas has an extremely high affinity for the ferrous heme-iron and is known to reduce ferric hemoproteins in the presence of suitable electron donors. We hypothesized that under in vivo plasma conditions, peroxides at low concentration can assist the reduction of metRH in presence of CO. The effect of CO on interaction of metRH with hydrophilic or hydrophobic peroxides was analyzed by following Soret and visible light absorption changes in reaction mixtures. It was found that under anaerobic conditions and low concentrations of RH and peroxides mimicking plasma conditions, peroxides served as electron donors and RH were reduced to their ferrous carboxy forms. The reaction rates were dependent on CO as well as peroxide concentrations. These results demonstrate that oxidative activity of acellular ferric RH and peroxides may be amended by CO turning on the reducing potential of peroxides and facilitating the formation of redox-inactive carboxyRH. Our data suggest the possible role of HO/CO in protection of vascular system from oxidative damage. PMID:22427940

  19. Catalytic iron oxide for lime regeneration in carbonaceous fuel combustion

    DOEpatents

    Shen, Ming-Shing; Yang, Ralph T.

    1980-01-01

    Lime utilization for sulfurous oxides absorption in fluidized combustion of carbonaceous fuels is improved by impregnation of porous lime particulates with iron oxide. The impregnation is achieved by spraying an aqueous solution of mixed iron sulfate and sulfite on the limestone before transfer to the fluidized bed combustor, whereby the iron compounds react with the limestone substrate to form iron oxide at the limestone surface. It is found that iron oxide present in the spent limestone acts as a catalyst to regenerate the spent limestone in a reducing environment. With only small quantities of iron oxide the calcium can be recycled at a significantly increased rate.

  20. The Iron-Catalyzed Oxidation of Hydrazine by Nitric Acid

    SciTech Connect

    Karraker, D.G.

    2001-07-17

    To assess the importance of iron to hydrazine stability, the study of hydrazine oxidation by nitric acid has been extended to investigate the iron-catalyzed oxidation. This report describes those results.

  1. Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

    NASA Astrophysics Data System (ADS)

    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

  2. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 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...

  3. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 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...

  4. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 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...

  5. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 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...

  6. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 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...

  7. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 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...

  8. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2010 CFR

    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...

  9. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2010 CFR

    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...

  10. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 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...

  11. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 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...

  12. Chemical design of biocompatible iron oxide nanoparticles for medical applications.

    PubMed

    Ling, Daishun; Hyeon, Taeghwan

    2013-05-27

    Iron oxide nanoparticles are one of the most versatile and safe nanomaterials used in medicine. Recent progress in nanochemistry enables fine control of the size, crystallinity, uniformity, and surface properties of iron oxide nanoparticles. In this review, the synthesis of chemically designed biocompatible iron oxide nanoparticles with improved quality and reduced toxicity is discussed for use in diverse biomedical applications.

  13. Acid monolayer functionalized iron oxide nanoparticle catalysts

    NASA Astrophysics Data System (ADS)

    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

  14. Ferrous iron oxidation by anoxygenic phototrophic bacteria

    NASA Astrophysics Data System (ADS)

    Widdel, Friedrich; Schnell, Sylvia; Heising, Silke; Ehrenreich, Armin; Assmus, Bernhard; Schink, Bernhard

    1993-04-01

    NATURAL oxidation of ferrous to ferric iron by bacteria such as Thiobacillus ferrooxidans or Gallionella ferruginea1, or by chemical oxidation2,3 has previously been thought always to involve molecular oxygen as the electron acceptor. Anoxic photochemical reactions4-6 or a photobiological process involving two photosystems7-9 have also been discussed as mechanisms of ferrous iron oxidation. The knowledge of such processes has implications that bear on our understanding of the origin of Precambrian banded iron formations10-14. The reducing power of ferrous iron increases dramatically at pH values higher than 2-3 owing to the formation of ferric hydroxy and oxyhydroxy compounds1,2,15 (Fig. 1). The standard redox potential of Fe3+/Fe2+ (E0 = +0.77 V) is relevant only under acidic conditions. At pH 7.0, the couples Fe(OH)3/Fe2+ (E'0 = -0.236V) or Fe(OH)3 + HCO-3FeCO3 (E'0 = +0.200 V) prevail, matching redox potentials measured in natural sediments9,16,17. It should thus be possible for Fe(n) around pH 7.0 to function as an electron donor for anoxygenic photosynthesis. The midpoint potential of the reaction centre in purple bacteria is around +0.45 V (ref. 18). Here we describe purple, non-sulphur bacteria that can indeed oxidize colourless Fe(u) to brown Fe(in) and reduce CO2 to cell material, implying that oxygen-independent biological iron oxidation was possible before the evolution of oxygenic photosynthesis.

  15. Review of world literature finds iron oxides noncarcinogenic

    SciTech Connect

    Stokinger, H.E.

    1984-02-01

    Iron oxide appeared in the first list of 154 Threshold Limit Values adopted by the American Conference of Governmental Industrial Hygienists at its April 1949 annual meeting. It was set to control dust and fume at the recommended value of 15 mg/M/sup 3/, at the time, the limit for an inert or ''nuisance'' dust, and was based on studies of welders made earlier by the US Dept. of Labor and by Drinker and Nelson. By 1964, the TLV was tentatively reduced to 10 mg/M/sup 3/ after a considerable body of literature had accumulated not only on the health experience of welders, but of other occupations involving iron oxides as well. As a group, these studies indicated that 15 mg/M/sup 3/ permitted too great accumulations of iron pigmentation in the lung whose chronic retention effects were not known with certainty. Also, an occasional report of cancer of the lungs appeared particulary among British hematite miners, although these findings were immediately questioned on statistical grounds. In seeming confirmation of these early reports of cancer, an alarming number of reports of cancer of the lung and respiratory tract among welders and foundrymen began to appear by 1970, reaching a crescendo by the end of that decade. As past chairman of the TLV Committee, the author decided to examine the bases of these findings. This review is the result of this examination.

  16. Nitric oxide and plant iron homeostasis.

    PubMed

    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.

  17. Formulations for iron oxides dissolution

    DOEpatents

    Horwitz, Earl P.; Chiarizia, Renato

    1992-01-01

    A mixture of a di- or polyphosphonic acid and a reductant wherein each is present in a sufficient amount to provide a synergistic effect with respect to the dissolution of metal oxides and optionally containing corrosion inhibitors and pH adjusting agents.

  18. Planktonic Marine Iron-Oxidizers Drive Iron(III) Mineralization Under Low Oxygen Conditions

    NASA Astrophysics Data System (ADS)

    Luther, G. W., III; Field, E.; Findlay, A.; MacDonald, D. J.; Chan, C. S. Y.; Kato, S.

    2016-02-01

    Observations of modern microbes have led to several hypotheses on how microbes precipitated the extensive banded iron formations in the geologic record, but we have yet to resolve the exact microbial contributions. An initial hypotheses was that cyanobacteria produced oxygen that oxidized iron(II) abiotically; however, in modern environments such as microbial mats, where Fe(II) and O2 coexist, we commonly find microaerophilic chemolithotrophic iron(II)-oxidizing bacteria producing Fe(III) oxyhydroxides. This suggests that such iron-oxidizers could have inhabited niches in ancient coastal oceans where Fe(II) and O2 coexisted, and therefore contributed to iron deposits, but there is currently little evidence for planktonic marine iron-oxidizers in modern analogs. Here, we demonstrate successful cultivation of planktonic microaerophilic iron-oxidizing Zetaproteobacteria from the Chesapeake Bay during seasonal stratification. Iron-oxidizers were associated with low oxygen concentrations and active iron redox cycling in the oxic-anoxic transition zone (<3 µM O2, <0.2 µM H2S). While cyanobacteria were also detected in this transition zone, oxygen concentrations were too low to support significant rates of abiotic iron oxidation. Instead, cyanobacteria may be providing oxygen for microaerophilic iron(II) oxidation through a symbiotic relationship that promotes oxygen consumption rather than build-up. Our results suggest that once oxygenic photosynthesis evolved, microaerophilic chemolithotrophic iron(II)-oxidizers were likely important drivers of iron(III) mineralization in ancient oceans.

  19. Nitric oxide and changes of iron metabolism in exercise.

    PubMed

    Qian, Zhong Ming

    2002-11-01

    Accumulated data imply that exercise itself might not lead to a true iron deficiency or 'sport anaemia' in a healthy athlete who has adequate iron intake. The higher prevalence of iron deficiency anaemia in younger female athletes might be not due to exercise itself, but probably results from dietary choices, inadequate iron intake and menstruation. These factors can also induce iron deficiency or anaemia in the general population. However, exercise does affect iron metabolism, leading to low or sub-optimal iron status. The underlying mechanism is unknown. In this review, recent advances in the study of the effect of exercise on iron metabolism and nitric oxide, and the relationship between nitric oxide and iron status in exercise are discussed. A hypothesis that increased production of nitric oxide might contribute to sub-optimal iron status in exercise is proposed.

  20. Method for preparing hydrous iron oxide gels and spherules

    DOEpatents

    Collins, Jack L.; Lauf, Robert J.; Anderson, Kimberly K.

    2003-07-29

    The present invention is directed to methods for preparing hydrous iron oxide spherules, hydrous iron oxide gels such as gel slabs, films, capillary and electrophoresis gels, iron monohydrogen phosphate spherules, hydrous iron oxide spherules having suspendable particles homogeneously embedded within to form composite sorbents and catalysts, iron monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent, iron oxide spherules having suspendable particles homogeneously embedded within to form a composite of hydrous iron oxide fiber materials, iron oxide fiber materials, hydrous iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, dielectric spherules of barium, strontium, and lead ferrites and mixtures thereof, and composite catalytic spherules of barium or strontium ferrite embedded with oxides of Mg, Zn, Pb, Ce and mixtures thereof. These variations of hydrous iron oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters, dielectrics, and ceramics.

  1. Oxidation Potentials in Iron and Steel Making

    NASA Astrophysics Data System (ADS)

    Matousek, J. W.

    2013-11-01

    The state of oxidation of a pyrometallurgical process given by the partial pressure of oxygen and the temperature (the oxidation potential) is one of the important properties monitored and controlled in the smelting and refining of iron and the nonferrous metals. Solid electrolyte sensors based on ZrO2 and a reference electrode such as Cr/Cr2O3 to measure the oxygen pressure found early application in the steel industry, followed soon after in copper, nickel, lead, and zinc smelting. Similar devices are installed in automobile postcombustion/exhaust trains as part of emission control systems. The current discussion reviews this technology as applied in the primary steps of iron and steel making and refining.

  2. Optical properties of iron oxides

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  5. Lower incidence of respiratory infections among iron-deficient children in Kilimanjaro, Tanzania.

    PubMed

    Wander, Katherine; Shell-Duncan, Bettina; Brindle, Eleanor

    2017-01-01

    Objective: We posited a trade-off in iron nutrition, with iron deficiency decreasing risk for infection by depriving infectious agents of iron while increasing risk for infection by compromising immune protection. We described associations between iron deficiency and prevalent and incident infectious disease episodes and cell-mediated immunity (CMI) among 283 children in Kilimanjaro, Tanzania. Methodology: Whole blood specimens were evaluated for hemoglobin and dried blood spots (DBS) were evaluated for biomarkers of iron deficiency (transferrin receptor) and inflammation (C-reactive protein and α1-acid glycoprotein). Prevalent and incident infectious disease episodes were identified by physician's diagnosis. CMI was evaluated as delayed-type hypersensitivity to Candida albicans (DTH-Candida). Associations between iron status and elevated inflammation, prevalent infectious disease episodes and DTH-Candida were described with logistic regression models; associations between iron status and incident infectious disease episodes were described with Cox proportional hazards models. Results: Elevated inflammation and diagnosed infectious diseases were more common among children with iron-deficiency anemia (IDA, severe iron deficiency), but not significantly so. The incidence of infectious disease was lowest among children with moderate iron deficiency (iron-deficient erythropoiesis, IDE); this pattern was most apparent for respiratory infections (aHR: 0.24; p: 0.030). DTH-Candida was not compromised among children with any degree of iron deficiency. Conclusions and implications: We observed no adverse effect of iron deficiency on CMI, but did observe patterns consistent with the hypothesis that moderate iron deficiency protects against respiratory infections and may represent a nutritional adaptation to infectious disease. This suggests that interventions targeting iron deficiency should be coupled with effective infectious disease control measures.

  6. Water clustering on nanostructured iron oxide films.

    PubMed

    Merte, Lindsay R; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A; Zeuthen, Helene; Knudsen, Jan; Lægsgaard, Erik; Wendt, Stefan; Mavrikakis, Manos; Besenbacher, Flemming

    2014-06-30

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule-molecule and molecule-surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, 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 moiré-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 water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moiré structure.

  7. Water Clustering on Nanostructured Iron Oxide Films

    SciTech Connect

    Merte, L. R.; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A.; Zeuthen, Helene; Knudsen, Jan; Laegsgaard, E.; Wendt, Stefen; Mavrikakis, Manos; Besenbacher, Fleming

    2014-06-30

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule–molecule and molecule–surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, 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 are 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 water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moire´ structure.

  8. Phase Formation Behavior in Ultrathin Iron Oxide.

    PubMed

    Jõgi, Indrek; Jacobsson, T Jesper; Fondell, Mattis; Wätjen, Timo; Carlsson, Jan-Otto; Boman, Mats; Edvinsson, Tomas

    2015-11-17

    Nanostructured iron oxides, and especially hematite, are interesting for a wide range of applications ranging from gas sensors to renewable solar hydrogen production. A promising method for deposition of low-dimensional films is atomic layer deposition (ALD). Although a potent technique, ALD of ultrathin films is critically sensitive to the substrate and temperature conditions where initial formation of islands and crystallites influences the properties of the films. In this work, deposition at the border of the ALD window forming a hybrid ALD/pulsed CVD (pCVD) deposition is utilized to obtain a deposition less sensitive to the substrate. A thorough analysis of iron oxide phases formation on two different substrates, Si(100) and SiO2, was performed. Films between 3 and 50 nm were deposited and analyzed with diffraction techniques, high-resolution Raman spectroscopy, and optical spectroscopy. Below 10 nm nominal film thickness, island formation and phase dependent particle crystallization impose constraints for deposition of phase pure iron oxides on non-lattice-matching substrates. Films between 10 and 20 nm thickness on SiO2 could effectively be recrystallized into hematite whereas for the corresponding films on Si(100), no recrystallization occurred. For films thicker than 20 nm, phase pure hematite can be formed directly with ALD/pCVD with very low influence of the substrate on either Si or SiO2. For more lattice matched substrates such as SnO2:F, Raman spectroscopy indicated formation of the hematite phase already for films with 3 nm nominal thickness and clearly for 6 nm films. Analysis of the optical properties corroborated the analysis and showed a quantum confined blue-shift of the absorption edge for the thinnest films.

  9. Iron Oxide Nanozyme: A Multifunctional Enzyme Mimetic for Biomedical Applications

    PubMed Central

    Gao, Lizeng; Fan, Kelong; Yan, Xiyun

    2017-01-01

    Iron oxide nanoparticles have been widely used in many important fields due to their excellent nanoscale physical properties, such as magnetism/superparamagnetism. They are usually assumed to be biologically inert in biomedical applications. However, iron oxide nanoparticles were recently found to also possess intrinsic enzyme-like activities, and are now regarded as novel enzyme mimetics. A special term, “Nanozyme”, has thus been coined to highlight the intrinsic enzymatic properties of such nanomaterials. Since then, iron oxide nanoparticles have been used as nanozymes to facilitate biomedical applications. In this review, we will introduce the enzymatic features of iron oxide nanozyme (IONzyme), and summarize its novel applications in biomedicine. PMID:28900505

  10. Mineral resource of the month: iron oxide pigments

    USGS Publications Warehouse

    ,

    2008-01-01

    The article discusses iron oxide pigments, which have been used as colorants since human began painting as they resist color change due to sunlight exposure, have good chemical resistance and are stable under normal ambient conditions. Cyprus, Italy and Spain are among the countries that are known for the production of iron oxide pigments. Granular forms of iron oxides and nano-sized materials are cited as developments in the synthetic iron oxide pigment industry which are being used in computer disk drives and nuclear magnetic resonance imaging.

  11. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    SciTech Connect

    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.

  12. Modified iron oxide nanomaterials: Functionalization and application

    NASA Astrophysics Data System (ADS)

    Bagheri, Samira; Julkapli, Nurhidayatullaili Muhd

    2016-10-01

    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.

  13. A Diatom Ferritin Optimized for Iron Oxidation but Not Iron Storage*

    PubMed Central

    Pfaffen, Stephanie; Bradley, Justin M.; Abdulqadir, Raz; Firme, Marlo R.; Moore, Geoffrey R.; Le Brun, Nick E.; Murphy, Michael E. P.

    2015-01-01

    Ferritin from the marine pennate diatom Pseudo-nitzschia multiseries (PmFTN) plays a key role in sustaining growth in iron-limited ocean environments. The di-iron catalytic ferroxidase center of PmFTN (sites A and B) has a nearby third iron site (site C) in an arrangement typically observed in prokaryotic ferritins. Here we demonstrate that Glu-44, a site C ligand, and Glu-130, a residue that bridges iron bound at sites B and C, limit the rate of post-oxidation reorganization of iron coordination and the rate at which Fe3+ exits the ferroxidase center for storage within the mineral core. The latter, in particular, severely limits the overall rate of iron mineralization. Thus, the diatom ferritin is optimized for initial Fe2+ oxidation but not for mineralization, pointing to a role for this protein in buffering iron availability and facilitating iron-sparing rather than only long-term iron storage. PMID:26396187

  14. Effects of coating spherical iron oxide nanoparticles

    SciTech Connect

    Milosevic, Irena; Motte, Laurence; Aoun, Bachir; Li, Tao; Ren, Yang; Sun, Chengjun; Saboungi, Marie-Louise

    2017-01-01

    We investigate the effect of several coatings applied in biomedical applications to iron oxide nanoparticles on the size, structure and composition of the particles. The four structural techniques employed - TEM, DLS, VSM, SAXS and EXAFS - show no significant effects of the coatings on the spherical shape of the bare nanoparticles, the average sizes or the local order around the Fe atoms. The NPs coated with hydroxylmethylene bisphosphonate or catechol have a lower proportion of magnetite than the bare and citrated ones, raising the question whether the former are responsible for increasing the valence state of the oxide on the NP surfaces and lowering the overall proportion of magnetite in the particles. VSM measurements show that these two coatings lead to a slightly higher saturation magnetization than the citrate. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazu and Dr. Federica Migliardo.

  15. Insight into the evolution of the iron oxidation pathways.

    PubMed

    Ilbert, Marianne; Bonnefoy, Violaine

    2013-02-01

    Iron is a ubiquitous element in the universe. Ferrous iron (Fe(II)) was abundant in the primordial ocean until the oxygenation of the Earth's atmosphere led to its widespread oxidation and precipitation. This change of iron bioavailability likely put selective pressure on the evolution of life. This element is essential to most extant life forms and is an important cofactor in many redox-active proteins involved in a number of vital pathways. In addition, iron plays a central role in many environments as an energy source for some microorganisms. This review is focused on Fe(II) oxidation. The fact that the ability to oxidize Fe(II) is widely distributed in Bacteria and Archaea and in a number of quite different biotopes suggests that the dissimilatory Fe(II) oxidation is an ancient energy metabolism. Based on what is known today about Fe(II) oxidation pathways, we propose that they arose independently more than once in evolution and evolved convergently. The iron paleochemistry, the phylogeny, the physiology of the iron oxidizers, and the nature of the cofactors of the redox proteins involved in these pathways suggest a possible scenario for the timescale in which each type of Fe(II) oxidation pathways evolved. The nitrate dependent anoxic iron oxidizers are likely the most ancient iron oxidizers. We suggest that the phototrophic anoxic iron oxidizers arose in surface waters after the Archaea/Bacteria-split but before the Great Oxidation Event. The neutrophilic oxic iron oxidizers possibly appeared in microaerobic marine environments prior to the Great Oxidation Event while the acidophilic ones emerged likely after the advent of atmospheric O(2). This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems.

  16. Superparamagnetic Iron Oxide Nanoparticles with Variable Size and an Iron Oxidation State as Prospective Imaging Agents

    PubMed Central

    Kucheryavy, Pavel; He, Jibao; John, Vijay T.; Maharjan, Pawan; Spinu, Leonard; Goloverda, Galina Z.; Kolesnichenko, Vladimir L.

    2013-01-01

    Magnetite nanoparticles in the size range of 3.2-7.5 nm were synthesized in high yields under variable reaction conditions using high-temperature hydrolysis of the precursor iron(II) and iron(III) alkoxides in diethylene glycol solution. The average sizes of the particles were adjusted by changing the reaction temperature and time and by using a sequential growth technique. To obtain γ-iron(III) oxide particles in the same range of sizes, magnetite particles were oxidized with dry oxygen in diethylene glycol at room temperature. The products were characterized by DLS, TEM, X-ray powder diffractometry, TGA, chemical analysis, and magnetic measurements. NMR r1 and r2 relaxivity measurements in water and diethylene glycol (for OH and CH2 protons) have shown a decrease in the r2/r1 ratio with the particle size reduction, which correlates with the results of magnetic measurements on magnetite nanoparticles. Saturation magnetization of the oxidized particles was found to be 20% lower than that for Fe3O4 with the same particle size, but their r1 relaxivities are similar. Because the oxidation of magnetite is spontaneous under ambient conditions, it was important to learn that the oxidation product has no disadvantages as compared to its precursor and therefore may be a better prospective imaging agent because of its chemical stability. PMID:23249219

  17. Battles with Iron: Manganese in Oxidative Stress Protection*

    PubMed Central

    Aguirre, J. Dafhne; Culotta, Valeria C.

    2012-01-01

    The redox-active metal manganese plays a key role in cellular adaptation to oxidative stress. As a cofactor for manganese superoxide dismutase or through formation of non-proteinaceous manganese antioxidants, this metal can combat oxidative damage without deleterious side effects of Fenton chemistry. In either case, the antioxidant properties of manganese are vulnerable to iron. Cellular pools of iron can outcompete manganese for binding to manganese superoxide dismutase, and through Fenton chemistry, iron may counteract the benefits of non-proteinaceous manganese antioxidants. In this minireview, we highlight ways in which cells maximize the efficacy of manganese as an antioxidant in the midst of pro-oxidant iron. PMID:22247543

  18. Uptake And Intracellular Distribution Of Functionalized Iron Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Panariti, A.; Lettiero, B.; Morjan, I.; Alexandreascu, R.; Wang, D.; Bucci, C.; Miserocchi, G.; Rivolta, I.

    2010-10-01

    Iron oxide Nanoparticles represents promising nanocarrier for magnetic resonance imaging (MRI), targeted drug and gene delivery. In our study we investigated the interaction between lung alveolar epithelial cells and iron oxide NPs coated with L-Dihydroxyphenylalanina (L-Dopa)-TRITC. Our data suggest that particles crossed the plasma membrane with an energy-dependent process.

  19. TRACE ELEMENT BINDING DURING STRUCTURAL TRANSFORMATION IN IRON OXIDES

    EPA Science Inventory

    Iron (hydr)oxides often control the mobility of inorganic contaminants in soils and sediments. A poorly ordered form of ferrihydrite is commonly produced during rapid oxidation of ferrous iron at sharp redox fronts encountered during discharge of anoxic/suboxic waters into terre...

  20. TRACE ELEMENT BINDING DURING STRUCTURAL TRANSFORMATION IN IRON OXIDES

    EPA Science Inventory

    Iron (hydr)oxides often control the mobility of inorganic contaminants in soils and sediments. A poorly ordered form of ferrihydrite is commonly produced during rapid oxidation of ferrous iron at sharp redox fronts encountered during discharge of anoxic/suboxic waters into terre...

  1. Modified Nanoemulsions with Iron Oxide for Magnetic Resonance Imaging

    PubMed Central

    Fan, Yongyi; Guo, Rui; Shi, Xiangyang; Allen, Steven; Cao, Zhengyi; Baker, James R.; Wang, Su He

    2016-01-01

    A nanoemulsion (NE) is a surfactant-based, oil-in-water, nanoscale, high-energy emulsion with a mean droplet diameter of 400–600 nm. When mixed with antigen and applied nasally, a NE acts as a mucosal adjuvant and induces mucosal immune responses. One possible mechanism for the adjuvant effect of this material is that it augments antigen uptake and distribution to lymphoid tissues, where the immune response is generated. Biocompatible iron oxide nanoparticles have been used as a unique imaging approach to study the dynamics of cells or molecular migration. To study the uptake of NEs and track them in vivo, iron oxide nanoparticles were synthesized and dispersed in soybean oil to make iron oxide-modified NEs. Our results show that iron oxide nanoparticles can be stabilized in the oil phase of the nanoemulsion at a concentration of 30 µg/μL and the iron oxide-modified NEs have a mean diameter of 521 nm. In vitro experiments demonstrated that iron oxide-modified NEs can affect uptake by TC-1 cells (a murine epithelial cell line) and reduce the intensity of magnetic resonance (MR) images by shortening the T2 time. Most importantly, in vivo studies demonstrated that iron oxide-modified NE could be detected in mouse nasal septum by both transmission electron microscopy and MR imaging. Altogether these experiments demonstrate that iron oxide-modified NE is a unique tool that can be used to study uptake and distribution of NEs after nasal application. PMID:28335351

  2. Ecological succession among iron-oxidizing bacteria.

    PubMed

    Fleming, Emily J; Cetinić, Ivona; Chan, Clara S; Whitney King, D; Emerson, David

    2014-04-01

    Despite over 125 years of study, the factors that dictate species dominance in neutrophilic iron-oxidizing bacterial (FeOB) communities remain unknown. In a freshwater wetland, we documented a clear ecological succession coupled with niche separation between the helical stalk-forming Gallionellales (for example, Gallionella ferruginea) and tubular sheath-forming Leptothrix ochracea. Changes in the iron-seep community were documented using microscopy and cultivation-independent methods. Quantification of Fe-oxyhydroxide morphotypes by light microscopy was coupled with species-specific fluorescent in situ hybridization (FISH) probes using a protocol that minimized background fluorescence caused by the Fe-oxyhydroxides. Together with scanning electron microscopy, these techniques all indicated that Gallionellales dominated during early spring, with L. ochracea becoming more abundant for the remainder of the year. Analysis of tagged pyrosequencing reads of the small subunit ribosomal RNA gene (SSU rRNA) collected during seasonal progression supported a clear Gallionellales to L. ochracea transition, and community structure grouped according to observed dominant FeOB forms. Axis of redundancy analysis of physicochemical parameters collected from iron mats during the season, plotted with FeOB abundance, corroborated several field and microscopy-based observations and uncovered several unanticipated relationships. On the basis of these relationships, we conclude that the ecological niche of the stalk-forming Gallionellales is in waters with low organic carbon and steep redoxclines, and the sheath-forming L. ochracea is abundant in waters that contain high concentrations of complex organic carbon, high Fe and Mn content and gentle redoxclines. Finally, these findings identify a largely unexplored relationship between FeOB and organic carbon.

  3. Ecological succession among iron-oxidizing bacteria

    PubMed Central

    Fleming, Emily J; Cetinić, Ivona; Chan, Clara S; Whitney King, D; Emerson, David

    2014-01-01

    Despite over 125 years of study, the factors that dictate species dominance in neutrophilic iron-oxidizing bacterial (FeOB) communities remain unknown. In a freshwater wetland, we documented a clear ecological succession coupled with niche separation between the helical stalk-forming Gallionellales (for example, Gallionella ferruginea) and tubular sheath-forming Leptothrix ochracea. Changes in the iron-seep community were documented using microscopy and cultivation-independent methods. Quantification of Fe-oxyhydroxide morphotypes by light microscopy was coupled with species-specific fluorescent in situ hybridization (FISH) probes using a protocol that minimized background fluorescence caused by the Fe-oxyhydroxides. Together with scanning electron microscopy, these techniques all indicated that Gallionellales dominated during early spring, with L. ochracea becoming more abundant for the remainder of the year. Analysis of tagged pyrosequencing reads of the small subunit ribosomal RNA gene (SSU rRNA) collected during seasonal progression supported a clear Gallionellales to L. ochracea transition, and community structure grouped according to observed dominant FeOB forms. Axis of redundancy analysis of physicochemical parameters collected from iron mats during the season, plotted with FeOB abundance, corroborated several field and microscopy-based observations and uncovered several unanticipated relationships. On the basis of these relationships, we conclude that the ecological niche of the stalk-forming Gallionellales is in waters with low organic carbon and steep redoxclines, and the sheath-forming L. ochracea is abundant in waters that contain high concentrations of complex organic carbon, high Fe and Mn content and gentle redoxclines. Finally, these findings identify a largely unexplored relationship between FeOB and organic carbon. PMID:24225888

  4. Bio-inspired Iron Catalysts for Hydrocarbon Oxidations

    SciTech Connect

    Que, Jr., Lawrence

    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.

  5. Microbially Induced Iron Oxidation: What, Where, How

    SciTech Connect

    SCHIERMEYER,ELISA M.; PROVENCIO,PAULA P.; NORTHUP,DIANA E.

    2000-08-15

    From the results of the different bacterial cells seen, it is fairly certain that Gallionella is present because of the bean-shaped cells and twisted stalks found with the TEM. The authors cannot confirm, though, what other iron-oxidizing genera exist in the tubes, since the media was only preferential and not one that isolated a specific genus of bacteria. Based on the environment in which they live and the source of the water, they believe their cultures contain Gallionella, Leptothrix, and possibly Crenothrix and Sphaerotilus. They believe the genus Leptothrix rather than Sphaerotilus exist in the tubes because the water source was fresh, unlike the polluted water in which Sphaerotilus are usually found. The TEM preparations worked well. The cryogenic method rapidly froze the cells in place and allowed them to view their morphology. The FAA method, as stated previously, was the best of the three methods because it gave the best contrast. The gluteraldehyde samples did not come out as well. It is possible that the gluteraldehyde the authors prepared was still too concentrated and did not mix well. Although these bacteria were collected from springs and then cultured in an environment containing a presumably pure iron-bearing metal, it seems the tube already containing Manganese Gradient Medium could be used with a piece of metal containing these bacteria. A small piece of corroding metal could then be inserted into the test tube and cultured to study the bacteria.

  6. Oxidation inhibits iron-induced blood coagulation.

    PubMed

    Pretorius, Etheresia; Bester, Janette; Vermeulen, Natasha; Lipinski, Boguslaw

    2013-01-01

    Blood coagulation under physiological conditions is activated by thrombin, which converts soluble plasma fibrinogen (FBG) into an insoluble clot. The structure of the enzymatically-generated clot is very characteristic being composed of thick fibrin fibers susceptible to the fibrinolytic degradation. However, in chronic degenerative diseases, such as atherosclerosis, diabetes mellitus, cancer, and neurological disorders, fibrin clots are very different forming dense matted deposits (DMD) that are not effectively removed and thus create a condition known as thrombosis. We have recently shown that trivalent iron (ferric ions) generates hydroxyl radicals, which subsequently convert FBG into abnormal fibrin clots in the form of DMDs. A characteristic feature of DMDs is their remarkable and permanent resistance to the enzymatic degradation. Therefore, in order to prevent thrombotic incidences in the degenerative diseases it is essential to inhibit the iron-induced generation of hydroxyl radicals. This can be achieved by the pretreatment with a direct free radical scavenger (e.g. salicylate), and as shown in this paper by the treatment with oxidizing agents such as hydrogen peroxide, methylene blue, and sodium selenite. Although the actual mechanism of this phenomenon is not yet known, it is possible that hydroxyl radicals are neutralized by their conversion to the molecular oxygen and water, thus inhibiting the formation of dense matted fibrin deposits in human blood.

  7. Iron oxide nanoparticle enhancement of radiation cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mazur, Courtney M.; Tate, Jennifer A.; Strawbridge, Rendall R.; Gladstone, David J.; Hoopes, P. Jack

    2013-02-01

    Iron oxide nanoparticles (IONPs) have been investigated as a promising means for inducing tumor cell-specific hyperthermia. Although the ability to generate and use nanoparticles that are biocompatible, tumor specific, and have the ability to produce adequate cytotoxic heat is very promising, significant preclinical and clinical development will be required for clinical efficacy. At this time it appears using IONP-induced hyperthermia as an adjunct to conventional cancer therapeutics, rather than as an independent treatment, will provide the initial IONP clinical treatment. Due to their high-Z characteristics, another option is to use intracellular IONPs to enhance radiation therapy without excitation with AMF (production of heat). To test this concept IONPs were added to cell culture media at a concentration of 0.2 mg Fe/mL and incubated with murine breast adenocarcinoma (MTG-B) cells for either 48 or 72 hours. Extracellular iron was then removed and all cells were irradiated at 4 Gy. Although samples incubated with IONPs for 48 hrs did not demonstrate enhanced post-irradiation cytotoxicity as compared to the non-IONP-containing cells, cells incubated with IONPs for 72 hours, which contained 40% more Fe than 48 hr incubated cells, showed a 25% decrease in clonogenic survival compared to their non-IONP-containing counterparts. These results suggest that a critical concentration of intracellular IONPs is necessary for enhancing radiation cytotoxicity.

  8. Multiple hearth furnace for reducing iron oxide

    DOEpatents

    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).

  9. Multifunctional iron oxide nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Bloemen, M.; Denis, C.; Van Stappen, T.; De Meester, L.; Geukens, N.; Gils, A.; Verbiest, T.

    2015-03-01

    Multifunctional nanoparticles have attracted a lot of attention since they can combine interesting properties like magnetism, fluorescence or plasmonic effects. As a core material, iron oxide nanoparticles have been the subject of intensive research. These cost-effective and non-toxic particles are used nowadays in many applications. We developed a heterobifunctional PEG ligand that can be used to introduce functional groups (carboxylic acids) onto the surface of the NP. Via click chemistry, a siloxane functionality was added to this ligand, for a subsequent covalent ligand exchange reaction. The functionalized nanoparticles have an excellent colloidal stability in complex environments like buffers and serum or plasma. Antibodies were coupled to the introduced carboxylic acids and these NP-antibody bioconjugates were brought into contact with Legionella bacteria for magnetic separation experiments.

  10. Biocompatible multishell architecture for iron oxide nanoparticles.

    PubMed

    Wotschadlo, Jana; Liebert, Tim; Clement, Joachim H; Anspach, Nils; Höppener, Stephanie; Rudolph, Tobias; Müller, Robert; Schacher, Felix H; Schubert, Ulrich S; Heinze, Thomas

    2013-01-01

    The coating of super-paramagnetic iron oxide nanoparticles (SPIONs) with multiple shells is demonstrated by building a layer assembled from carboxymethyldextran and poly(diallydimethylammonium chloride). Three shells are produced stepwise around aggregates of SPIONs by the formation of a polyelectrolyte complex. A growing particle size from 96 to 327 nm and a zeta potential in the range of +39 to -51 mV are measured. Microscopic techniques such as TEM, SEM, and AFM exemplify the core-shell structures. Magnetic force microscopy and vibrating sample magnetometer measurements confirm the architecture of the multishell particles. Cell culture experiments show that even nanoparticles with three shells are still taken up by cells.

  11. Artificial meteor ablation studies - Iron oxides.

    NASA Technical Reports Server (NTRS)

    Blanchard, M. B.

    1972-01-01

    Artificial meteor ablation was performed on natural minerals composed predominantly of magnetite and hematite by using an arc-heated plasma stream of air. Analysis indicates that most of the ablated debris was composed of two or more minerals. Wustite, a metastable mineral, was found to occur as a common product. The 'magnetite' sample, which was 80% magnetite, 14% hematite, 4% apatite, and 2% quartz, yielded ablated products consisting of more than 12 different minerals. Magnetite occurred in 91% of the specimens examined, hematite in 16%, and wustite in 30%. The 'hematite' sample, which was 96% hematite and 3% quartz, yielded ablated products consisting of more than 13 different minerals. Hematite occurred in 47% of the specimens examined, magnetite in 60%, and wustite in 28%. The more volatile elements (Si, P, and Cl) were depleted by about 50%. This study has shown that artificially created ablation products from iron oxides exhibit unique properties that can be used for identification.

  12. Controlling barrier penetration via exothermic iron oxidation.

    PubMed

    Wood, Daniel G; Brown, Marc B; Jones, Stuart A

    2011-02-14

    Exothermic iron oxidation is an elegant means to generate heat, with the potential to modulate barrier penetration if reaction kinetics can be controlled. This aim of this study was to gain a fundamental understanding of how these temperature change kinetics influenced barrier diffusion rate. Lidocaine transport through a hydrophilic carboxymethyl cellulose (CMC) gel was compared using two rapid iron oxidation reactions initiated by water (ExoRap(50), T(max)-47.7 ± 0.6 °C, t(max)-3.3 ± 0.6 min, ExoRap(60), T(max)-60.4 ± 0.3 °C, t(max)-9.3 ± 0.6 min) and a slower reaction initiated by oxygen (ExoSl(45)T(max)-ca. 44 °C, t(max) ca. 240 min). Temperature change induced by the oxygen initiated reaction (ExoSl(45)) was almost double those initiated by water (over 4h), but lidocaine diffusion was approximately 4 times higher for the latter (ExoRap(50), 555.61 ± 22.04 μg/cm(2)/h; ExoRap(60), 663.1 ± 50.95 μg/cm(2)/h; compared to ExoSl(45), 159.36 ± 29.44 μg/cm(2)/h). The large influence of temperature change kinetics on lidocaine diffusion suggested that transport was heavily dependent on temperature induced structural changes of the barrier. CMC, like many polymers adsorbs more water when exposed to moderate increases in temperature and this appeared to be a critical determinant of lidocaine barrier diffusion rate. Copyright © 2010 Elsevier B.V. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Effects of iron chelators, iron salts, and iron oxide nanoparticles on the proliferation and the iron content of oligodendroglial OLN-93 cells.

    PubMed

    Hohnholt, Michaela; Geppert, Mark; Dringen, Ralf

    2010-08-01

    The oligodendroglial cell line OLN-93 was used as model system to investigate the consequences of iron deprivation or iron excess on cell proliferation. Presence of ferric or ferrous iron chelators inhibited the proliferation of OLN-93 cells in a time and concentration dependent manner, while the application of a molar excess of ferric ammonium citrate (FAC) prevented the inhibition of proliferation by the chelator deferoxamine. Proliferation of OLN-93 cells was not affected by incubation with 300 microM iron that was applied in the form of FAC, FeCl(2), ferrous ammonium sulfate or iron oxide nanoparticles, although the cells efficiently accumulated iron during exposure to each of these iron sources. The highest specific iron content was observed for cells that were exposed to the nanoparticles. These data demonstrate that the proliferation of OLN-93 cells depends strongly on the availability of iron and that these cells efficiently accumulate iron from various extracellular iron sources.

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

    PubMed

    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.

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

    PubMed Central

    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

  17. Studies of the kinetics and mechanisms of perfluoroether reactions on iron and oxidized iron surfaces

    NASA Technical Reports Server (NTRS)

    Napier, Mary E.; Stair, Peter C.

    1992-01-01

    Polymeric perfluoroalkylethers are being considered for use as lubricants in high temperature applications, but have been observed to catalytically decompose in the presence of metals. X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) were used to explore the decomposition of three model fluorinated ethers on clean polycrystalline iron surfaces and iron surfaces chemically modified with oxygen. Low temperature adsorption of the model fluorinated ethers on the clean, oxygen modified and oxidized iron surfaces was molecular. Thermally activated defluorination of the three model compounds was observed on the clean iron surface at remarkably low temperatures, 155 K and below, with formation of iron fluoride. Preferential C-F bond scission occurred at the terminal fluoromethoxy, CF3O, of perfluoro-1-methoxy-2-ethoxy ethane and perfluoro-1-methoxy-2-ethoxy propane and at CF3/CF2O of perfluoro-1,3-diethoxy propane. The reactivity of the clean iron toward perfluoroalkylether decomposition when compared to other metals is due to the strength of the iron fluoride bond and the strong electron donating ability of the metallic iron. Chemisorption of an oxygen overlayer lowered the reactivity of the iron surface to the adsorption and decomposition of the three model fluorinated ethers by blocking active sites on the metal surface. Incomplete coverage of the iron surface with chemisorbed oxygen results in a reaction which resembles the defluorination reaction observed on the clean iron surface. Perfluoro-1-methoxy-2-ethoxy ethane reacts on the oxidized iron surface at 138 K, through a Lewis acid assisted cleavage of the carbon oxygen bond, with preferential attack at the terminal fluoromethoxy, CF3O. The oxidized iron surface did not passivate, but became more reactive with time. Perfluoro-1-methoxy-2-ethoxy propane and perfluoro-1,3-diethoxy propane desorbed prior to the observation of decomposition on the oxidized iron surface.

  18. Iron photoreduction and oxidation in an acidic mountain stream

    USGS Publications Warehouse

    McKnight, D.M.; Kimball, B.A.; Bencala, K.E.

    1988-01-01

    In a small mountain stream in Colorado that receives acidic mine drainage, photoreduction of ferric iron results in a well-defined increase in dissolved ferrous iron during the day. To quantify this process, an instream injection of a conservative tracer was used to measure discharge at the time that each sample was collected. Daytime production of ferrous iron by photoreduction was almost four times as great as nighttime oxidation of ferrous iron. The photoreduction process probably involves dissolved or colloidal ferric iron species and limited interaction with organic species because concentrations of organic carbon are low in this stream.

  19. Iron photoreduction and oxidation in an acidic mountain stream.

    PubMed

    McKnight, D M; Kimball, B A; Bencala, K E

    1988-04-29

    In a small mountain stream in Colorado that receives acidic mine drainage, photoreduction of ferric iron results in a well-defined increase in dissolved ferrous iron during the day. To quantify this process, an instream injection of a conservative tracer was used to measure discharge at the time that each sample was collected. Daytime production of ferrous iron by photoreduction was almost four times as great as nighttime oxidation of ferrous iron. The photoreduction process probably involves dissolved or colloidal ferric iron species and limited interaction with organic species because concentrations of organic carbon are low in this stream.

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

    SciTech Connect

    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.

  1. The multitude of iron-sulfur clusters in respiratory complex I.

    PubMed

    Gnandt, Emmanuel; Dörner, Katerina; Strampraad, Marc F J; de Vries, Simon; Friedrich, Thorsten

    2016-08-01

    Respiratory complex I couples the electron transfer from NADH to ubiquinone with the translocation of protons across the membrane. Complex I contains one non-covalently bound flavin mononucleotide and, depending on the species, up to ten iron-sulfur (Fe/S) clusters as cofactors. The reason for the presence of the multitude of Fe/S clusters in complex I remained enigmatic for a long time. The question was partly answered by investigations on the evolution of the complex revealing the stepwise construction of the electron transfer domain from several modules. Extension of the ancestral to the modern electron input domain was associated with the acquisition of several Fe/S-proteins. The X-ray structure of the complex showed that the NADH oxidation-site is connected with the quinone-reduction site by a chain of seven Fe/S-clusters. Fast enzyme kinetics revealed that this chain of Fe/S-clusters is used to regulate electron-tunneling rates within the complex. A possible function of the off-pathway cluster N1a is discussed. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.

  2. Investigation of oxidation process of mechanically activated ultrafine iron powders

    NASA Astrophysics Data System (ADS)

    Lysenko, E. N.; Nikolaev, E. V.; Vlasov, V. A.; Zhuravkov, S. P.

    2016-02-01

    The oxidation of mechanically activated ultrafine iron powders was studied using X- ray powder diffraction and thermogravimetric analyzes. The powders with average particles size of 100 nm were made by the electric explosion of wire, and were subjected to mechanical activation in planetary ball mill for 15 and 40 minutes. It was shown that a certain amount of FeO phase is formed during mechanical activation of ultrafine iron powders. According to thermogravimetric analysis, the oxidation process of non-milled ultrafine iron powders is a complex process and occurs in three stages. The preliminary mechanical activation of powders considerably changes the nature of the iron powders oxidation, leads to increasing in the temperature of oxidation onset and shifts the reaction to higher temperatures. For the milled powders, the oxidation is more simple process and occurs in a single step.

  3. Nitric Oxide Improves Internal Iron Availability in Plants1

    PubMed Central

    Graziano, Magdalena; Beligni, María Verónica; Lamattina, Lorenzo

    2002-01-01

    Iron deficiency impairs chlorophyll biosynthesis and chloroplast development. In leaves, most of the iron must cross several biological membranes to reach the chloroplast. The components involved in the complex internal iron transport are largely unknown. Nitric oxide (NO), a bioactive free radical, can react with transition metals to form metal-nitrosyl complexes. Sodium nitroprusside, an NO donor, completely prevented leaf interveinal chlorosis in maize (Zea mays) plants growing with an iron concentration as low as 10 μm Fe-EDTA in the nutrient solution. S-Nitroso-N-acetylpenicillamine, another NO donor, as well as gaseous NO supply in a translucent chamber were also able to revert the iron deficiency symptoms. A specific NO scavenger, 2-(4-carboxy-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, blocked the effect of the NO donors. The effect of NO treatment on the photosynthetic apparatus of iron-deficient plants was also studied. Electron micrographs of mesophyll cells from iron-deficient maize plants revealed plastids with few photosynthetic lamellae and rudimentary grana. In contrast, in NO-treated maize plants, mesophyll chloroplast appeared completely developed. NO treatment did not increase iron content in plant organs, when expressed in a fresh matter basis, suggesting that root iron uptake was not enhanced. NO scavengers 2-(4-carboxy-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and methylene blue promoted interveinal chlorosis in iron-replete maize plants (growing in 250 μm Fe-EDTA). Even though results support a role for endogenous NO in iron nutrition, experiments did not establish an essential role. NO was also able to revert the chlorotic phenotype of the iron-inefficient maize mutants yellow stripe1 and yellow stripe3, both impaired in the iron uptake mechanisms. All together, these results support a biological action of NO on the availability and/or delivery of metabolically active iron within the plant. PMID:12481068

  4. Application of novel iron core/iron oxide shell nanoparticles to sentinel lymph node identification

    NASA Astrophysics Data System (ADS)

    Cousins, Aidan; Howard, Douglas; Henning, Anna M.; Nelson, Melanie R. M.; Tilley, Richard D.; Thierry, Benjamin

    2015-12-01

    Current `gold standard' staging of breast cancer and melanoma relies on accurate in vivo identification of the sentinel lymph node. By replacing conventional tracers (dyes and radiocolloids) with magnetic nanoparticles and using a handheld magnetometer probe for in vivo identification, it is believed the accuracy of sentinel node identification in nonsuperficial cancers can be improved due to increased spatial resolution of magnetometer probes and additional anatomical information afforded by MRI road-mapping. By using novel iron core/iron oxide shell nanoparticles, the sensitivity of sentinel node mapping via MRI can be increased due to an increased magnetic saturation compared to traditional iron oxide nanoparticles. A series of in vitro magnetic phantoms (iron core vs. iron oxide nanoparticles) were prepared to simulate magnetic particle accumulation in the sentinel lymph node. A novel handheld magnetometer probe was used to measure the relative signals of each phantom, and determine if clinical application of iron core particles can improve in vivo detection of the sentinel node compared to traditional iron oxide nanoparticles. The findings indicate that novel iron core nanoparticles above a certain size possess high magnetic saturation, but can also be produced with low coercivity and high susceptibility. While some modification to the design of handheld magnetometer probes may be required for particles with large coercivity, use of iron core particles could improve MRI and magnetometer probe detection sensitivity by up to 330 %.

  5. Oxidative Stress and the Homeodynamics of Iron Metabolism

    PubMed Central

    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

  6. Oxidation state of iron in plagioclase from lunar basalts.

    NASA Technical Reports Server (NTRS)

    Hafner, S. S.; Virgo, D.; Warburton, D.

    1971-01-01

    Determination of the oxidation state of iron in the plagioclase from the coarse-grained basalts 10044 and 12021, using Mossbauer spectroscopy. The location of iron in the crystal structure was also investigated. The spectra show that iron is in the high-spin ferrous state, and they located at least two distinct positions with different coordination numbers. Some excess resonant absorption is probably due to Fe(3+), although the Fe(3+) doublet could not be positively resolved.

  7. Oxidation state of iron in plagioclase from lunar basalts.

    NASA Technical Reports Server (NTRS)

    Hafner, S. S.; Virgo, D.; Warburton, D.

    1971-01-01

    Determination of the oxidation state of iron in the plagioclase from the coarse-grained basalts 10044 and 12021, using Mossbauer spectroscopy. The location of iron in the crystal structure was also investigated. The spectra show that iron is in the high-spin ferrous state, and they located at least two distinct positions with different coordination numbers. Some excess resonant absorption is probably due to Fe(3+), although the Fe(3+) doublet could not be positively resolved.

  8. Magnetic Characterization of Iron Oxide Cross Linked Hydro gels

    NASA Astrophysics Data System (ADS)

    Senaratne, U.; Powell, N.; Kroll, E.; Tsoi, G.; Naik, R.; Naik, V.; Vaishnava, P. P.; Wenger, L. E.

    2004-03-01

    Magnetic hydro gels have potential applications in drug delivery, cells sorting, sensors, and actuating technologies. Iron oxide alginate nanocomposites were synthesized following the method of Kroll et al^1 by cross linking sodium alginate with Fe^2+ and Fe^3+ in methanol: water. The ion-cross linked alginate hydro gels are oxidized in an alkaline solution. The resulting hydro gel consists of iron oxide cross linked alginate. The alginate hydro gels are inert to the reaction conditions and therefore the reaction sequence can be repeated. The multiple loadings result in an increase in the amount of iron oxide and the size of the iron oxide nanoparticles in the cross linked hydro gels. The third and sixth loaded iron oxide alginate hydro gels were dried and characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), and Superconducting Quantum Interference Device (SQUID) magnetometry. The XRD patterns have characteristic features of γ- Fe_2O3 or Fe_3O4 phases. The average particle size, calculated from the XRD peaks, for third loaded iron oxide alginate was 2 nm. The zero-field-cooled and field-cooled SQUID measurements show the iron oxide nanoparticles are superparamagnetic with blocking temperature (T_B) of approximately 35 K. Above the blocking temperature, the inverse susceptibility versus temperature relationship does not follow the Curie-Weiss law, indicating strong inter-particle interactions. The M vs. H data above the blocking temperature was fitted with a modified Langevin function to obtain additional information about the iron oxide particle size. Details of the relationship between coercive field and temperature as well as the particle size distribution obtained from XRD and TEM measurements will be presented. *Research supported by NSF grant # DGE ˜980720 **Supported by NSF REU grant # EEC-0097736 ^1E. Kroll, F.M. Winnik, and R.F. Ziolo, Chem. Mater, 8, 1594 (1996).

  9. Immobilisation of arsenic by iron(II)-oxidizing bacteria

    NASA Astrophysics Data System (ADS)

    Kappler, A.; Hohmann, C.; Winkler, E.; Muehe, M.; Morin, G.

    2008-12-01

    Arsenic-contaminated groundwater is an environmental problem that affects about 1-2% of the world's population. As arsenic-contaminated water is also used for irrigating rice fields, the uptake of arsenic via rice is in some cases even higher than via drinking water. Arsenic is often of geogenic origin and in many cases bound to iron(III) minerals. Microbial iron(III) reduction leads to dissolution of Fe(III) minerals and thus the arsenic bound to these minerals is released to the environment. In turn, iron(II)-oxidizing bacteria have the potential to co-precipitate or sorb arsenic during iron(II) oxidation followed by iron(III) mineral formation. Here, we present work on arsenic co-precipitation and immobilization by anaerobic and aerobic iron(II)-oxidizing bacteria. Co-precipitation batch experiments with pure cultures of nitrate-dependent, phototrophic, and microaerophilic Fe(II)-oxidizing bacteria are used to quantify the amount of arsenic that can be immobilized during microbial iron mineral precipitation. Iron and arsenic speciation and redox state are determined by X- ray diffraction and synchrotron-based X-ray absorption methods (EXAFS, XANES). Microcosm experiments are set-up either with liquid media or with rice paddy soil amended with arsenic. Rice paddy soil from arsenic contaminated rice fields in China that include a natural population of Fe(II)-oxidizing microorganisms is used as inoculum. Dissolved and solid-phase arsenic and iron are quantified, Arsenic speciation is determined and the iron minerals are identified. Additionally, Arsenic uptake into the rice plant is quantified and a gene expression pattern in rice (Oryza sativa cv Gladia) is determined by microarrays as a response to the presence of Fe(II)-oxidizing bacteria.

  10. Biogenic Fabrication of Iron/Iron Oxide Nanoparticles and Their Application

    NASA Astrophysics Data System (ADS)

    Siddiqi, Khwaja Salahuddin; ur Rahman, Aziz; Tajuddin; Husen, Azamal

    2016-11-01

    Enshrined in this review are the biogenic fabrication and applications of coated and uncoated iron and iron oxide nanoparticles. Depending on their magnetic properties, they have been used in the treatment of cancer, drug delivery system, MRI, and catalysis and removal of pesticides from potable water. The polymer-coated iron and iron oxide nanoparticles are made biocompatible, and their slow release makes them more effective and lasting. Their cytotoxicity against microbes under aerobic/anaerobic conditions has also been discussed. The magnetic moment of superparamagnetic iron oxide nanoparticles changes with their interaction with biomolecules as a consequence of which their size decreases. Their biological efficacy has been found to be dependent on the shape, size, and concentration of these nanoparticles.

  11. Design of Fucoidan Functionalized - Iron Oxide Nanoparticles for Biomedical Applications.

    PubMed

    Tran, Khanh Nghia; Tran, Phuong Ha-Lien; Vo, Toi Van; Tran, Thao Truong-Dinh

    2016-01-01

    This research aims to develop an iron oxide nanoparticle drug delivery system utilizing a recent material discovered from ocean, fucoidan. The material has drawn much interest due to many biomedical functions that have been proven for human health. One interesting point herein is that fucoidan is not only a sulfated polysaccharide, a polymer for stabilization of iron oxide nanoparticles, but plays a role of an anticancer agent also. Various approaches were investigated to optimize the high loading efficiency and explain the mechanism of nanoparticle formations. Fucoidan was functionalized on iron oxide nanoparticles by a direct coating or via amine groups. Also, a hydrophobic part of oleic acid was conjugated to the amine groups for a more favorable loading of poorly water-soluble anticancer drugs. This study proposed a novel system and an efficient method to functionalize fucoidan on iron oxide nanoparticle systems which will lead to a facilitation of a double strength treatment of cancer.

  12. Dissolution of iron oxide nanoparticles inside polymer nanocapsules.

    PubMed

    Möller, Johannes; Cebi, Melek; Schroer, Martin A; Paulus, Michael; Degen, Patrick; Sahle, Christoph J; Wieland, D C Florian; Leick, Sabine; Nyrow, Alexander; Rehage, Heinz; Tolan, Metin

    2011-12-07

    The structure of poly(organosiloxane) nanocapsules partially filled with iron oxide cores of different sizes was revealed by small angle X-ray scattering and X-ray diffraction. The nanocapsules are synthesized by the formation of a poly(organosiloxane) shell around iron oxide nanoparticles and the simultaneous partial dissolution of these cores. Due to the high scattering contrast of the iron oxide cores compared to the polymer shell, the particle size distribution of the cores inside the capsules can be measured by small angle X-ray scattering. Additional information can be revealed by X-ray diffraction, which gives insights into the formation of the polymer network and the structure of the iron oxide cores. The study shows how the crystallinity and size of the nanoparticles as well as the shape and width of the size distribution can be altered by the synthesis parameters.

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

    PubMed Central

    2008-01-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed. PMID:21749733

  14. Respiratory Diseases in Iron Ore Miners and Millers

    PubMed Central

    Edstrom, Harry W.

    1989-01-01

    Workers in iron mines are at risk of developing interstitial lung disease if the dust levels are above the threshold limit value. However, they more commonly develop the usual diseases that affect all workers. Some illnesses, such as chronic bronchitis, bronchial asthma, and the collagen vascular diseases that affect the lung, may be more severe because of the inhalation of dust. The most difficult problem is to differentiate asymptomatic sarcoidosis from pneumoconiosis. The family doctor who also acts as the company doctor must be aware of the potential conflict of interest. PMID:21248910

  15. Iron oxide surface-catalyzed oxidation of ferrous iron by monochloramine: implications of oxide type and carbonate on reactivity.

    PubMed

    Vikesland, Peter J; Valentine, Richard L

    2002-02-01

    The maintenance of monochloramine residuals in drinking water distribution systems is one technique often used to minimize microbial outbreaks and thereby maintain the safety of the water. Reactions between oxidizable species and monochloramine can however lead to undesirable losses in the disinfectant residual. Previous work has illustrated that the Fe(II) present within distribution systems is one type of oxidizable species that can exert a monochloramine demand. This paper extends this prior work by examining the kinetics of the reactions between Fe(II) and monochloramine in the presence of a variety of iron oxide surfaces. The identity of the iron oxide plays a significant role in the rate of these reactions. Surface area-normalized initial rate coefficients (k(init)) obtained in the presence of each oxide at pH approximately 6.9 exhibit the following trend in catalytic activity: magnetite > goethite > hematite approximately = lepidocrocite > ferrihydrite. The differences in the activity of these oxides are hypothesized to result from variations in the amount of Fe(II) sorbed to each of the oxides and to dissimilarities in the surface site densities of the oxides. The implications of carbonate on Fe(II) sorption to iron oxides are also examined. Comparing Fe(II) sorption isotherms for goethite obtained under differential carbonate concentrations, it is apparent that as the carbonate concentration (C(T,CO3)) increased from 0 to 11.7 mM that the Fe(II) sorption edge (50% sorption) shifts from a pH of approximately 5.8 to a pH of 7.8. This shift is hypothesized to be the result of the formation of aqueous and surface carbonate-Fe(II) complexes and to competition between carbonate and Fe(II) for surface sites. The implications of these changes are then discussed in light of the variable oxide studies.

  16. Long term in vivo biotransformation of iron oxide nanoparticles.

    PubMed

    Levy, Michael; Luciani, Nathalie; Alloyeau, Damien; Elgrabli, Dan; Deveaux, Vanessa; Pechoux, Christine; Chat, Sophie; Wang, Guillaume; Vats, Nidhi; Gendron, François; Factor, Cécile; Lotersztajn, Sophie; Luciani, Alain; Wilhelm, Claire; Gazeau, Florence

    2011-06-01

    The long term outcome of nanoparticles in the organism is one of the most important concerns raised by the development of nanotechnology and nanomedicine. Little is known on the way taken by cells to process and degrade nanoparticles over time. In this context, iron oxide superparamagnetic nanoparticles benefit from a privileged status, because they show a very good tolerance profile, allowing their clinical use for MRI diagnosis. It is generally assumed that the specialized metabolism which regulates iron in the organism can also handle iron oxide nanoparticles. However the biotransformation of iron oxide nanoparticles is still not elucidated. Here we propose a multiscale approach to study the fate of nanomagnets in the organism. Ferromagnetic resonance and SQUID magnetization measurements are used to quantify iron oxide nanoparticles and follow the evolution of their magnetic properties. A nanoscale structural analysis by electron microscopy complements the magnetic follow-up of nanoparticles injected to mice. We evidence the biotransformation of superparamagnetic maghemite nanoparticles into poorly-magnetic iron species probably stored into ferritin proteins over a period of three months. A putative mechanism is proposed for the biotransformation of iron-oxide nanoparticles. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Iron Oxide Nanocrystals for Magnetic Hyperthermia Applications

    PubMed Central

    Armijo, Leisha M.; Brandt, Yekaterina I.; Mathew, Dimple; Yadav, Surabhi; Maestas, Salomon; Rivera, Antonio C.; Cook, Nathaniel C.; Withers, Nathan J.; Smolyakov, Gennady A.; Adolphi, Natalie; Monson, Todd C.; Huber, Dale L.; Smyth, Hugh D. C.; Osiński, Marek

    2012-01-01

    Magnetic nanocrystals have been investigated extensively in the past several years for several potential applications, such as information technology, MRI contrast agents, and for drug conjugation and delivery. A specific property of interest in biomedicine is magnetic hyperthermia—an increase in temperature resulting from the thermal energy released by magnetic nanocrystals in an external alternating magnetic field. Iron oxide nanocrystals of various sizes and morphologies were synthesized and tested for specific losses (heating power) using frequencies of 111.1 kHz and 629.2 kHz, and corresponding magnetic field strengths of 9 and 25 mT. Polymorphous nanocrystals as well as spherical nanocrystals and nanowires in paramagnetic to ferromagnetic size range exhibited good heating power. A remarkable 30 °C temperature increase was observed in a nanowire sample at 111 kHz and magnetic field of 25 mT (19.6 kA/m), which is very close to the typical values of 100 kHz and 20 mT used in medical treatments.

  18. Anthropogenic iron oxide aerosols enhance atmospheric heating

    PubMed Central

    Moteki, Nobuhiro; Adachi, Kouji; Ohata, Sho; Yoshida, Atsushi; Harigaya, Tomoo; Koike, Makoto; Kondo, Yutaka

    2017-01-01

    Combustion-induced carbonaceous aerosols, particularly black carbon (BC) and brown carbon (BrC), have been largely considered as the only significant anthropogenic contributors to shortwave atmospheric heating. Natural iron oxide (FeOx) has been recognized as an important contributor, but the potential contribution of anthropogenic FeOx is unknown. In this study, we quantify the abundance of FeOx over East Asia through aircraft measurements using a modified single-particle soot photometer. The majority of airborne FeOx particles in the continental outflows are of anthropogenic origin in the form of aggregated magnetite nanoparticles. The shortwave absorbing powers (Pabs) attributable to FeOx and to BC are calculated on the basis of their size-resolved mass concentrations and the mean Pabs(FeOx)/Pabs(BC) ratio in the continental outflows is estimated to be at least 4–7%. We demonstrate that in addition to carbonaceous aerosols the aggregate of magnetite nanoparticles is a significant anthropogenic contributor to shortwave atmospheric heating. PMID:28508863

  19. Stem cell tracking using iron oxide nanoparticles.

    PubMed

    Bull, Elizabeth; Madani, Seyed Yazdan; Sheth, Roosey; Seifalian, Amelia; Green, Mark; Seifalian, Alexander M

    2014-01-01

    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.

  20. Photocatalytic water oxidation with iron oxide hydroxide (rust) nanoparticles

    NASA Astrophysics Data System (ADS)

    Shelton, Timothy L.; Bensema, Bronwyn L.; Brune, Nicholas K.; Wong, Christopher; Yeh, Max; Osterloh, Frank E.

    2017-01-01

    Hematite has attracted considerable interest as a photoanode material for water oxidation under visible illumination. Here, we explore the limits of photocatalytic water oxidation activity with iron (III) oxide hydroxide nanocrystals and NaIO4 as a sacrificial electron acceptor (E=1.63 V NHE at pH=0.5). The sol was prepared by hydrolysis of FeCl3 in boiling 0.002-M HCl solution and confirmed to mainly consist of ß-FeO(OH) (akaganéite) particles with 5 to 15 nm diameter. From a 0.01 M aqueous NaIO4 solution, the sol evolves between 4.5 and 35.2 μmol O2 h-1, depending on pH, light intensity (>400 nm, 290 to 700 mW cm-2), ß-FeO(OH), and NaIO4 concentration. The activity increases with pH, and depends linearly on light intensity and photocatalyst amount, and it varies with sacrificial electron donor concentration. Under optimized conditions, the apparent quantum efficiency is 0.19% (at 400 nm and 460 mW cm-2), and the turnover number is 2.58 based on total ß-FeO(OH). Overall, the efficiency of the ß-FeO(OH)/NaIO4 photocatalytic system is limited by electron hole recombination and by particle aggregation over longer irradiation times (24 h). Lastly, surface photovoltage measurements on ß-FeO(OH) films on fluorine doped tin oxide substrate confirm a 2.15 eV effective band gap for the material.

  1. Recycling of iron via autophagy is critical for the transition from glycolytic to respiratory growth.

    PubMed

    Horie, Tetsuro; Kawamata, Tomoko; Matsunami, Miou; Ohsumi, Yoshinori

    2017-05-19

    Autophagy is a bulk degradation process conserved from yeast to mammals. To examine the roles of autophagy in cellular metabolism, we generated autophagy-defective (atg) mutants in the X2180-1B strain background. We compared the growth of wild-type (WT) and atg cells in minimal (synthetic dextrose, SD) and rich (yeast extract/peptone/dextrose, YEPD) medium, and we found that mutations in the core autophagy machinery result in defects in the diauxic shift, the transition from fermentation to respiratory growth upon glucose depletion, specifically in SD. Furthermore, we confirmed that autophagy was induced prior to the diauxic shift, implying that it plays a role in this process. In YEPD, atg mutants grew normally, so we assumed that the insufficiency of certain nutrients in SD was responsible for the defects. We ultimately identified iron, which is a necessary cofactor for respiratory activity, as the nutrient required for the diauxic shift in atg mutants. Indeed, atg mutants exhibited defects in respiration, which was rescued by supplementation with iron. Based on these data, we hypothesized that autophagy is involved in iron recycling during the diauxic shift. smf3Δfet5Δ or smf3Δftr1Δ cells, which are unable to export iron from the vacuole, also exhibit defects in the diauxic shift, so iron released from the vacuole is important for the shift in SD medium. Finally, we observed that smf3Δfet5Δ cells accumulated nearly twice as much vacuolar iron as smf3Δfet5Δatg2Δ cells, suggesting that autophagy is involved in iron recycling by the vacuolar transport and degradation of iron-containing cargos. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

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

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

    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 3O 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 3O 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 (MS) of Fe/Fe 3O 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 3O 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. Synthesis and heating effect of iron/iron oxide composite and iron oxide nanoparticles

    PubMed Central

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

    2014-01-01

    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 FeCl3 within a NaBH4 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/Fe3O4 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/Fe3O4 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 (MS) of Fe/Fe3O4 particles (100–190 emu/g) can be twice as high, and the coercivity (HC) can be tunable from several Oe to several hundred Oe. Hence, the SAR of Fe/Fe3O4 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. PMID:25301983

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

    PubMed Central

    Meng Lin, Meng; Kim, Hyung-Hwan; Kim, Hyuck; Muhammed, Mamoun; Kyung Kim, Do

    2010-01-01

    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. PMID:22110854

  5. Iron Oxide Silica Derived from Sol-Gel Synthesis

    PubMed Central

    Darmawan, Adi; Smart, Simon; Julbe, Anne; Diniz da Costa, João Carlos

    2011-01-01

    In this work we investigate the effect of iron oxide embedded in silica matrices as a function of Fe/Si molar ratio and sol pH. To achieve homogeneous dispersion of iron oxide particles, iron nitrate nonahydrate was dissolved in hydrogen peroxide and was mixed with tetraethyl orthosilicate and ethanol in a sol-gel synthesis method. Increasing the calcination temperature led to a reduction in surface area, although the average pore radius remained almost constant at about 10 Å, independent of the Fe/Si molar ratio or sol pH. Hence, the densification of the matrix was accompanied by similar reduction in pore volume. However, calcination at 700 °C resulted in samples with similar surface area though the iron oxide content increased from 5% to 50% Fe/Si molar ratio. As metal oxide particles have lower surface area than polymeric silica structures, these results strongly suggest that the iron oxides opposed the silica structure collapse. The effect of sol pH was found to be less significant than the Fe/Si molar ratio in the formation of molecular sieve structures derived from iron oxide silica. PMID:28879999

  6. Iron oxide nanoparticles in geomicrobiology: from biogeochemistry to bioremediation.

    PubMed

    Braunschweig, Juliane; Bosch, Julian; Meckenstock, Rainer U

    2013-09-25

    Iron oxides are important constituents of soils and sediments and microbial iron reduction is considered to be a significant anaerobic respiration process in the subsurface, however low microbial reduction rates of macroparticulate Fe oxides in laboratory studies led to an underestimation of the role of Fe oxides in the global Fe redox cycle. Recent studies show the high potential of nano-sized Fe oxides in the environment as, for example, electron acceptor for microbial respiration, electron shuttle between different microorganisms, and scavenger for heavy metals. Biotic and abiotic reactivity of iron macroparticles differ significantly from nano-sized Fe oxides, which are usually much more reactive. Factors such as particle size, solubility, ferrous iron, crystal structure, and organic molecules were identified to influence the reactivity. This review discusses factors influencing the microbial reactivity of Fe oxides. It highlights the differences between natural and synthetic Fe oxides especially regarding the presence of organic molecules such as humic acids and natural organic matter. Attention is given to the transport behavior of Fe oxides in laboratory systems and in the environment, because of the high affinity of different contaminants to Fe oxide surfaces and associated co-transport of pollutants. The high reactivity of Fe oxides and their potential as adsorbents for different pollutants are discussed with respect to application and development of remediation technologies. Copyright © 2013. Published by Elsevier B.V.

  7. Iron assimilation and utilization in anaerobic ammonium oxidizing bacteria.

    PubMed

    Ferousi, Christina; Lindhoud, Simon; Baymann, Frauke; Kartal, Boran; Jetten, Mike Sm; Reimann, Joachim

    2017-04-01

    The most abundant transition metal in biological systems is iron. It is incorporated into protein cofactors and serves either catalytic, redox or regulatory purposes. Anaerobic ammonium oxidizing (anammox) bacteria rely heavily on iron-containing proteins - especially cytochromes - for their energy conservation, which occurs within a unique organelle, the anammoxosome. Both their anaerobic lifestyle and the presence of an additional cellular compartment challenge our understanding of iron processing. Here, we combine existing concepts of iron uptake, utilization and metabolism, and cellular fate with genomic and still limited biochemical and physiological data on anammox bacteria to propose pathways these bacteria may employ. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Measurements of nitric oxide on the heme iron and -93 thiol of human hemoglobin during cycles of oxygenation and deoxygenation

    NASA Astrophysics Data System (ADS)

    Xu, Xiuli; Cho, Man; Spencer, Netanya Y.; Patel, Neil; Huang, Zhi; Shields, Howard; King, S. Bruce; Gladwin, Mark T.; Hogg, Neil; Kim-Shapiro, Daniel B.

    2003-09-01

    Nitric oxide has been proposed to be transported by hemoglobin as a third respiratory gas and to elicit vasodilation by an oxygen-linked (allosteric) mechanism. For hemoglobin to transport nitric oxide bioactivity it must capture nitric oxide as iron nitrosyl hemoglobin rather than destroy it by dioxygenation. Once bound to the heme iron, nitric oxide has been reported to migrate reversibly from the heme group of hemoglobin to the -93 cysteinyl residue, in response to an oxygen saturation-dependent conformational change, to form an S-nitrosothiol. However, such a transfer requires redox chemistry with oxidation of the nitric oxide or -93 cysteinyl residue. In this article, we examine the ability of nitric oxide to undergo this intramolecular transfer by cycling human hemoglobin between oxygenated and deoxygenated states. Under various conditions, we found no evidence for intramolecular transfer of nitric oxide from either cysteine to heme or heme to cysteine. In addition, we observed that contaminating nitrite can lead to formation of iron nitrosyl hemoglobin in deoxygenated hemoglobin preparations and a radical in oxygenated hemoglobin preparations. Using 15N-labeled nitrite, we clearly demonstrate that nitrite chemistry could explain previously reported results that suggested apparent nitric oxide cycling from heme to thiol. Consistent with our results from these experiments conducted in vitro, we found no arterial/venous gradient of iron nitrosyl hemoglobin detectable by electron paramagnetic resonance spectroscopy. Our results do not support a role for allosterically controlled intramolecular transfer of nitric oxide in hemoglobin as a function of oxygen saturation.

  9. Iron, oxidative stress, and redox signaling in the cardiovascular system.

    PubMed

    Gudjoncik, Aurélie; Guenancia, Charles; Zeller, Marianne; Cottin, Yves; Vergely, Catherine; Rochette, Luc

    2014-08-01

    The redox state of the cell is predominantly dependent on an iron redox couple and is maintained within strict physiological limits. Iron is an essential metal for hemoglobin synthesis in erythrocytes, for oxidation-reduction reactions, and for cellular proliferation. The maintenance of stable iron concentrations requires the coordinated regulation of iron transport into plasma from dietary sources in the duodenum, from recycled senescent red cells in macrophages, and from storage in hepatocytes. The absorption of dietary iron, which is present in heme or nonheme form, is carried out by mature villus enterocytes of the duodenum and proximal jejunum. Multiple physiological processes are involved in maintaining iron homeostasis. These include its storage at the intracellular and extracellular level. Control of iron balance in the whole organism requires communication between sites of uptake, utilization, and storage. Key protein transporters and the molecules that regulate their activities have been identified. In this field, ferritins and hepcidin are the major regulator proteins. A variety of transcription factors may be activated depending on the level of oxidative stress, leading to the expression of different genes. Major preclinical and clinical trials have shown advances in iron-chelation therapy for the treatment of iron-overload disease as well as cardiovascular and chronic inflammatory diseases. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    PubMed

    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

  11. Synthesis of monodisperse iron oxide and iron/iron oxide core/shell nanoparticles via iron-oleylamine complex.

    PubMed

    Yu, S; Chow, G M

    2006-07-01

    Monodisperse magnetic nanoparticles are of great scientific and technical interests. This paper reports a single-step synthesis of monodisperse magnetite nanoparticles with particle size of 8 nm. Iron/maghaemite core/shell nanoparticles with particle size of 11 nm were obtained by reducing the concentration of oleylamine. TEM and in-situ FTIR results suggested that iron-oleylamine intermediate was generated in-situ and decomposed at higher temperature. Oleylamine was also found on the surface of nanoparticles, indicating its role as capping agent which provided steric protection of as-synthesized nanoparticles from agglomeration. Both magnetite and iron/maghaemite core/shell nanoparticles were superparamagnetic at room temperature with a blocking temperature at 80 K and 67 K, respectively.

  12. Oxidation-Induced Degradable Nanogels for Iron Chelation

    NASA Astrophysics Data System (ADS)

    Liu, Zhi; Wang, Yan; Purro, Max; Xiong, May P.

    2016-02-01

    Iron overload can increase cellular oxidative stress levels due to formation of reactive oxygen species (ROS); untreated, it can be extremely destructive to organs and fatal to patients. Since elevated oxidative stress levels are inherent to the condition in such patients, oxidation-induced degradable nanogels for iron chelation were rationally designed by simultaneously polymerizing oxidation-sensitive host-guest crosslinkers between β-cyclodextrin (β-CD) and ferrocene (Fc) and iron chelating moieties composed of deferoxamine (DFO) into the final gel scaffold in reverse emulsion reaction chambers. UV-Vis absorption and atomic absorption spectroscopy (AAS) was used to verify iron chelating capability of nanogels. These materials can degrade into smaller chelating fragments at rates proportional to the level of oxidative stress present. Conjugating DFO reduces the cytotoxicity of the chelator in the macrophage cells. Importantly, the nanogel can effectively reduce cellular ferritin expression in iron overloaded cells and regulate intracellular iron levels at the same time, which is important for maintaining a homeostatic level of this critical metal in cells.

  13. Oxidation-Induced Degradable Nanogels for Iron Chelation

    PubMed Central

    Liu, Zhi; Wang, Yan; Purro, Max; Xiong, May P.

    2016-01-01

    Iron overload can increase cellular oxidative stress levels due to formation of reactive oxygen species (ROS); untreated, it can be extremely destructive to organs and fatal to patients. Since elevated oxidative stress levels are inherent to the condition in such patients, oxidation-induced degradable nanogels for iron chelation were rationally designed by simultaneously polymerizing oxidation-sensitive host-guest crosslinkers between β-cyclodextrin (β-CD) and ferrocene (Fc) and iron chelating moieties composed of deferoxamine (DFO) into the final gel scaffold in reverse emulsion reaction chambers. UV-Vis absorption and atomic absorption spectroscopy (AAS) was used to verify iron chelating capability of nanogels. These materials can degrade into smaller chelating fragments at rates proportional to the level of oxidative stress present. Conjugating DFO reduces the cytotoxicity of the chelator in the macrophage cells. Importantly, the nanogel can effectively reduce cellular ferritin expression in iron overloaded cells and regulate intracellular iron levels at the same time, which is important for maintaining a homeostatic level of this critical metal in cells. PMID:26868174

  14. Photocatalysis over titania on iron oxide

    NASA Astrophysics Data System (ADS)

    Kim, Kwi Cheol; Han, Chong Soo

    2006-03-01

    Photocatalytic activity of TiO{2} deposited on spherical sub micron-sized Fe{2}O{3} particle was investigated under ultraviolet or visible light. The Fe{2}O{3} particles were prepared using a spray pyrolysis of aqueous Fe(NO{3})3 solution in air flow. TiO{2} was deposited on Fe{2}O{3} particle by irradiation of ultraviolet or visible light to the suspension of Fe{2}O{3} particle and a TiO{2} precursor. When TiO{2} was formed under visible light (TiO{2}/Fe{2}O{3}-VIS), there were reasonable trends in the phase shift of PAS signal and EDX signal of Ti. However, there was no trend for the case of ultra violet irradiation (TiO{2}/Fe{2}O{3}-UV). TiO{2}/Fe{2}O{3}-VIS showed higher rates of decomposition of organic compound, of decrease in contact angle of water drop, and of decrease in the number of E. coli under visible light than TiO{2}/Fe{2}O{3}-UV or TiO{2} film. From the results, it was suggested that TiO{2}/Fe{2}O{3}-VIS had a regular thin layer of TiO{2} compared to TiO{2}/Fe{2}O{3}-UV and the photo-generated carrier(s) in iron oxide migrated to the surface of TiO{2} in the case of TiO{2}/Fe{2}O{3}-VIS.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Comparative proteomic analysis of sulfur-oxidizing Acidithiobacillus ferrooxidans CCM 4253 cultures having lost the ability to couple anaerobic elemental sulfur oxidation with ferric iron reduction.

    PubMed

    Kucera, Jiri; Sedo, Ondrej; Potesil, David; Janiczek, Oldrich; Zdrahal, Zbynek; Mandl, Martin

    2016-09-01

    In extremely acidic environments, ferric iron can be a thermodynamically favorable electron acceptor during elemental sulfur oxidation by some Acidithiobacillus spp. under anoxic conditions. Quantitative 2D-PAGE proteomic analysis of a resting cell suspension of a sulfur-grown Acidithiobacillus ferrooxidans CCM 4253 subculture that had lost its iron-reducing activity revealed 147 protein spots that were downregulated relative to an iron-reducing resting cell suspension of the antecedent sulfur-oxidizing culture and 111 that were upregulated. Tandem mass spectrometric analysis of strongly downregulated spots identified several physiologically important proteins that apparently play roles in ferrous iron oxidation, including the outer membrane cytochrome Cyc2 and rusticyanin. Other strongly repressed proteins were associated with sulfur metabolism, including heterodisulfide reductase, thiosulfate:quinone oxidoreductase and sulfide:quinone reductase. Transcript-level analyses revealed additional downregulation of other respiratory genes. Components of the iron-oxidizing system thus apparently play central roles in anaerobic sulfur oxidation coupled with ferric iron reduction in the studied microbial strain.

  17. ISOLATION AND PROPERTIES OF AN IRON-OXIDIZING THIOBACILLUS

    PubMed Central

    Razzell, W. E.; Trussell, P. C.

    1963-01-01

    Razzell, W. E. (British Columbia Research Council, Vancouver, Canada) and P. C. Trussell. Isolation and properties of an iron-oxidizing Thiobacillus. J. Bacteriol. 85:595–603. 1963. — An organism isolated from acidic copper-leaching waters has been shown to oxidize ferrous ions, sulfur, and metallic sulfides but exhibit peculiar responses to thiosulfate. The name Thiobacillus ferrooxidans has been used to describe it. A pH of 2.5 is optimal for growth on iron, sulfur, and metallic sulfides, but cells free from iron can be obtained from growth at pH 1.6, and sulfur cultures adjusted to pH 5.5 readily attain a pH of 1.8. A stationary cultivation procedure appears superior to percolation techniques for studying the oxidation of finely divided metallic sulfides. Concentrations of soluble copper in excess of 1 g per liter were obtained from chalcopyrite in less than 4 weeks. Chalcocite oxidation proceeded in the absence of iron. Sodium chloride inhibits iron oxidation without preventing oxidation of metallic sulfides by the organism. PMID:14042937

  18. Controlled oxidation of iron nanoparticles in chemical vapour synthesis

    NASA Astrophysics Data System (ADS)

    Ruusunen, Jarno; Ihalainen, Mika; Koponen, Tarmo; Torvela, Tiina; Tenho, Mikko; Salonen, Jarno; Sippula, Olli; Joutsensaari, Jorma; Jokiniemi, Jorma; Lähde, Anna

    2014-02-01

    In the present study, iron oxide nanoparticles (primary particle size of 80-90 nm) with controlled oxidation state were prepared via an atmospheric pressure chemical vapour synthesis (APCVS) method. Iron pentacarbonyl [Fe(CO)5], a precursor material, was thermally decomposed to iron in the APCVS reactor. Subsequently, the iron was oxidized with controlled amount of oxygen in the reactor to produce nearly pure magnetite or haematite particles depending on the oxygen concentration. Size, morphology and crystal structure of the synthesized nanoparticles were studied with scanning mobility particle sizer (SMPS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). In addition, thermodynamic equilibrium calculations and computational fluid dynamics model were used to predict the oxidation state of the iron oxides and the reaction conditions during mixing. Aggregates of crystalline particles were formed, determined as magnetite at the oxygen volumetric fraction of 0.1 % and haematite at volumetric fraction of 0.5 %, according to the XRD. The geometric mean electrical mobility diameter of the aggregates increased from 110 to 155 nm when the volumetric fraction of oxygen increased from 0.1 to 0.5 %, determined using the SMPS. The aggregates were highly sintered based on TEM analyses. As a conclusion, APCVS method can be used to produce nearly pure crystalline magnetite or haematite nanoparticles with controlled oxidation in a continuous one-stage gas-phase process.

  19. Synthesis of phase pure praseodymium barium copper iron oxide.

    PubMed

    Konne, Joshua L; Davis, Sean A; Glatzel, Stefan; Hall, Simon R

    2013-06-18

    The control of crystallization of praseodymium barium copper iron oxide, an intermediate temperature solid oxide fuel cell cathode material, has been demonstrated for the first time using a biotemplated sol-gel synthesis technique. The results obtained showed significant improvement in purity, synthesis time, surface area and simplicity over that previously reported.

  20. The Oxidation Of Iron In A Gel Using Consumer Chemicals

    ERIC Educational Resources Information Center

    Wright, Stephen W.; Folger, Marsha R.; Quinn, Ryan P.; Sauls, Frederick C.; Krone, Diane

    2005-01-01

    An experiment is conducted for the oxidation of iron in a gel using consumer chemicals, which is pertinent to the students' understanding of redox chemistry and of the relative oxidation potentials of various metals. The experiment can be carried out with consumer chemicals that might be purchased at a supermarket and commonly found in the home.

  1. The Oxidation Of Iron In A Gel Using Consumer Chemicals

    ERIC Educational Resources Information Center

    Wright, Stephen W.; Folger, Marsha R.; Quinn, Ryan P.; Sauls, Frederick C.; Krone, Diane

    2005-01-01

    An experiment is conducted for the oxidation of iron in a gel using consumer chemicals, which is pertinent to the students' understanding of redox chemistry and of the relative oxidation potentials of various metals. The experiment can be carried out with consumer chemicals that might be purchased at a supermarket and commonly found in the home.

  2. Heterogeneous Fenton oxidation of ofloxacin drug by iron alginate support.

    PubMed

    Titouhi, Hana; Belgaied, Jamel-Eddine

    2016-08-01

    A new catalytic wet peroxide oxidation of ofloxacin antibiotic is presented in this work. The removal was achieved using a biodegradable sodium alginate-iron material. Several parameters were studied such as iron content, drying duration of the catalytic support, temperature, solid amount and initial drug concentration. The process showed a strong oxidative ability; at optimum conditions, a nearly complete removal of the drug (around 98%) has been reached after three h of treatment. A relatively low decrease of support activity (around 10%) has been observed after three successive oxidation runs and a low iron leaching has been detected (1.2% of the incorporated quantity). The removal of the substrate has been also examined in the absence of hydrogen peroxide in order to discriminate between the contributions of simple adsorption and oxidation processes in the drug disappearance. We also discussed the influence of the studied experimental parameters on the removal kinetic.

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    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 H2O2 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 H2O2 by NP surface generated OH• were investigated. Depending on the ratio of iron and H2O2, 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.

  4. Iron and oxidative stress in cardiomyopathy in thalassemia.

    PubMed

    Berdoukas, Vasilios; Coates, Thomas D; Cabantchik, Zvi Ioav

    2015-11-01

    With repeated blood transfusions, patients with thalassemia major rapidly become loaded with iron, often surpassing hepatic metal accumulation capacity within ferritin shells and infiltrating heart and endocrine organs. That pathological scenario contrasts with the physiological one, which is characterized by an efficient maintenance of all plasma iron bound to circulating transferrin, due to a tight control of iron ingress into plasma by the hormone hepcidin. Within cells, most of the acquired iron becomes protein-associated, as once released from endocytosed transferrin, it is used within mitochondria for the synthesis of protein prosthetic groups or it is incorporated into enzyme active centers or alternatively sequestered within ferritin shells. A few cell types also express the iron extrusion transporter ferroportin, which is under the negative control of circulating hepcidin. However, that system only backs up the major cell regulated iron uptake/storage machinery that is poised to maintain a basal level of labile cellular iron for metabolic purposes without incurring potentially toxic scenarios. In thalassemia and other transfusion iron-loading conditions, once transferrin saturation exceeds about 70%, labile forms of iron enter the circulation and can gain access to various types of cells via resident transporters or channels. Within cells, they can attain levels that exceed their ability to chemically cope with labile iron, which has a propensity for generating reactive oxygen species (ROS), thereby inducing oxidative damage. This scenario occurs in the heart of hypertransfused thalassemia major patients who do not receive adequate iron-chelation therapy. Iron that accumulates in cardiomyocytes forms agglomerates that are detected by T2* MRI. The labile forms of iron infiltrate the mitochondria and damage cells by inducing noxious ROS formation, resulting in heart failure. The very rapid relief of cardiac dysfunction seen after intensive iron

  5. Effect of green tea on iron status and oxidative stress in iron-loaded rats.

    PubMed

    Ounjaijean, S; Thephinlap, C; Khansuwan, U; Phisalapong, C; Fucharoen, S; Porter, J B; Srichairatanakool, S

    2008-07-01

    Plasma non-transferrin bound iron (NTBI) is potentially toxic and contributes to the generation of reactive oxygen species (ROS), consequently leading to tissue damage and organ dysfunction. Iron chelators and antioxidants are used for treatment of thalassemia patients. Green tea (GT) contains catechins derivatives that have many biological activities. The purpose of this study was to investigate the iron-chelating and free-radical scavenging capacities of green tea extract in vivo. Rats were injected ip with ferric citrate together with orally administered GT extract (GTE) for 4 months. Blood was collected monthly for measurement of iron overload and oxidative stress indicators. Plasma iron (PI) and total iron-binding capacity (TIBC) were quantified using bathophenanthroline method. Plasma NTBI was assayed with NTA chelation/HPLC. Plasma malonyldialdehyde (MDA) was determined by using the TBARS method. Erythrocyte oxidative stress was assessed using flow cytometry. Levels of PI, TIBC, NTBI and MDA, and erythrocyte ROS increased in the iron-loaded rats. Intervention with GT extract markedly decreased the PI and TIBC concentrations. It also lowered the transferrin saturation and effectively inhibited formation of NTBI. It also decreased the levels of erythrocyte ROS in week 4, 12 and 16. Therefore, green tea extract can decrease iron in plasma as well as eliminate lipid peroxidation in plasma, and destroy formation of erythrocyte ROS in the rats challenged with iron. The bifunctional effects could be beneficial in alleviating the iron and oxidative stress toxicity. In prospective, these GTE activities should be further examined in thalassemic animals or humans.

  6. A chameleon catalyst for nonheme iron-promoted olefin oxidation.

    PubMed

    Iyer, Shyam R; Javadi, Maedeh Moshref; Feng, Yan; Hyun, Min Young; Oloo, Williamson N; Kim, Cheal; Que, Lawrence

    2014-11-18

    We report the chameleonic reactivity of two nonheme iron catalysts for olefin oxidation with H2O2 that switch from nearly exclusive cis-dihydroxylation of electron-poor olefins to the exclusive epoxidation of electron-rich olefins upon addition of acetic acid. This switching suggests a common precursor to the nucleophilic oxidant proposed to Fe(III)-η(2)-OOH and electrophilic oxidant proposed to Fe(V)(O)(OAc), and reversible coordination of acetic acid as a switching pathway.

  7. Iron oxide and gold nanoparticles in cancer therapy

    NASA Astrophysics Data System (ADS)

    Gotman, Irena; Psakhie, Sergey G.; Lozhkomoev, Aleksandr S.; Gutmanas, Elazar Y.

    2016-08-01

    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.

  8. Iron oxide and gold nanoparticles in cancer therapy

    SciTech Connect

    Gotman, Irena Gutmanas, Elazar Y.; Psakhie, Sergey G.; Lozhkomoev, Aleksandr S.

    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.

  9. Development and use of iron oxide nanoparticles (Part 1): Synthesis of iron oxide nanoparticles for MRI

    PubMed Central

    Lodhia, J; Mandarano, G; Ferris, NJ; Eu, P; Cowell, SF

    2010-01-01

    Contrast agents, such as iron oxide, enhance MR images by altering the relaxation times of tissues in which the agent is present. They can also be used to label targeted molecular imaging probes. Unfortunately, no molecular imaging probe is currently available on the clinical MRI market. A promising platform for MRI contrast agent development is nanotechnology, where superparamagnetic iron oxide nanoparticles (SPIONS) are tailored for MR contrast enhancement, and/or for molecular imaging. SPIONs can be produced using a range of methods and the choice of method will be influenced by the characteristics most important for a particular application. In addition, the ability to attach molecular markers to SPIONS heralds their application in molecular imaging. There are many reviews on SPION synthesis for MRI; however, these tend to be targeted to a chemistry audience. The development of MRI contrast agents attracts experienced researchers from many fields including some researchers with little knowledge of medical imaging or MRI. This situation presents medical radiation practitioners with opportunities for involvement, collaboration or leadership in research depending on their level of commitment and their ability to learn. Medical radiation practitioners already possess a large portion of the understanding, knowledge and skills necessary for involvement in MRI development and molecular imaging. Their expertise in imaging technology, patient care and radiation safety provides them with skills that are directly applicable to research on the development and application of SPIONs and MRI. In this paper we argue that MRI SPIONs, currently limited to major research centres, will have widespread clinical use in the future. We believe that knowledge about this growing area of research provides an opportunity for medical radiation practitioners to enhance their specialised expertise to ensure best practice in a truly multi-disciplinary environment. This review outlines how and

  10. A pentanuclear iron catalyst designed for water oxidation

    NASA Astrophysics Data System (ADS)

    Okamura, Masaya; Kondo, Mio; Kuga, Reiko; Kurashige, Yuki; Yanai, Takeshi; Hayami, Shinya; Praneeth, Vijayendran K. K.; Yoshida, Masaki; Yoneda, Ko; Kawata, Satoshi; Masaoka, Shigeyuki

    2016-02-01

    Although the oxidation of water is efficiently catalysed by the oxygen-evolving complex in photosystem II (refs 1 and 2), it remains one of the main bottlenecks when aiming for synthetic chemical fuel production powered by sunlight or electricity. Consequently, the development of active and stable water oxidation catalysts is crucial, with heterogeneous systems considered more suitable for practical use and their homogeneous counterparts more suitable for targeted, molecular-level design guided by mechanistic understanding. Research into the mechanism of water oxidation has resulted in a range of synthetic molecular catalysts, yet there remains much interest in systems that use abundant, inexpensive and environmentally benign metals such as iron (the most abundant transition metal in the Earth’s crust and found in natural and synthetic oxidation catalysts). Water oxidation catalysts based on mononuclear iron complexes have been explored, but they often deactivate rapidly and exhibit relatively low activities. Here we report a pentanuclear iron complex that efficiently and robustly catalyses water oxidation with a turnover frequency of 1,900 per second, which is about three orders of magnitude larger than that of other iron-based catalysts. Electrochemical analysis confirms the redox flexibility of the system, characterized by six different oxidation states between FeII5 and FeIII5; the FeIII5 state is active for oxidizing water. Quantum chemistry calculations indicate that the presence of adjacent active sites facilitates O-O bond formation with a reaction barrier of less than ten kilocalories per mole. Although the need for a high overpotential and the inability to operate in water-rich solutions limit the practicality of the present system, our findings clearly indicate that efficient water oxidation catalysts based on iron complexes can be created by ensuring that the system has redox flexibility and contains adjacent water-activation sites.

  11. A pentanuclear iron catalyst designed for water oxidation.

    PubMed

    Okamura, Masaya; Kondo, Mio; Kuga, Reiko; Kurashige, Yuki; Yanai, Takeshi; Hayami, Shinya; Praneeth, Vijayendran K K; Yoshida, Masaki; Yoneda, Ko; Kawata, Satoshi; Masaoka, Shigeyuki

    2016-02-25

    Although the oxidation of water is efficiently catalysed by the oxygen-evolving complex in photosystem II (refs 1 and 2), it remains one of the main bottlenecks when aiming for synthetic chemical fuel production powered by sunlight or electricity. Consequently, the development of active and stable water oxidation catalysts is crucial, with heterogeneous systems considered more suitable for practical use and their homogeneous counterparts more suitable for targeted, molecular-level design guided by mechanistic understanding. Research into the mechanism of water oxidation has resulted in a range of synthetic molecular catalysts, yet there remains much interest in systems that use abundant, inexpensive and environmentally benign metals such as iron (the most abundant transition metal in the Earth's crust and found in natural and synthetic oxidation catalysts). Water oxidation catalysts based on mononuclear iron complexes have been explored, but they often deactivate rapidly and exhibit relatively low activities. Here we report a pentanuclear iron complex that efficiently and robustly catalyses water oxidation with a turnover frequency of 1,900 per second, which is about three orders of magnitude larger than that of other iron-based catalysts. Electrochemical analysis confirms the redox flexibility of the system, characterized by six different oxidation states between Fe(II)5 and Fe(III)5; the Fe(III)5 state is active for oxidizing water. Quantum chemistry calculations indicate that the presence of adjacent active sites facilitates O-O bond formation with a reaction barrier of less than ten kilocalories per mole. Although the need for a high overpotential and the inability to operate in water-rich solutions limit the practicality of the present system, our findings clearly indicate that efficient water oxidation catalysts based on iron complexes can be created by ensuring that the system has redox flexibility and contains adjacent water-activation sites.

  12. Modeling of iron oxide deposition by reactive ion beam sputtering

    SciTech Connect

    Puech, Laurent; Dubarry, Christophe; Ravel, Guillaume; Vito, Eric de

    2010-03-15

    An analytic model of deposition is applied on reactive ion beam sputtering to optimize the properties of iron oxide thin films. This model will be able to predict deposition rate and phase contents. Among its hypotheses, we assume oxygen adsorption at the surface of the target to explain variations of deposition rate for oxygen flow. This hypothesis is validated by chemical analyses on iron targets. An ellipsoidal distribution of probability is introduced to model sputtered matter distribution from iron target and to calculate sputtering yield. Comparison between experimental and calculated deposition rates validates previously assumed hypotheses.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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-Fe2O3 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-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 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.

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

    PubMed

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

    2015-05-22

    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-Fe2O3 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-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 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.

  15. Characterization of iron oxide layers using Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Bizjak, Milan; Zalar, Anton; Panjan, Peter; Zorko, Benjamin; Praček, Borut

    2007-02-01

    Metals can form several kinds of oxides. Iron forms wustite (FeO), magnetite (FeO + Fe 2O 3 or Fe 3O 4) and haematite (Fe 2O 3). Iron oxides, especially magnetite, are used for insulation between the lamellas of an electromotor made of electromagnetic sheet. In this work, iron oxide layers were characterized on industrial samples of electromagnetic sheet by AES depth profile analysis, and iron oxides with known chemical composition were used as reference samples, i.e. a magnetite mineral and a standard haematite reference sample. The magnetite mineral was chosen because it can be found in nature in a very pure form. The selection of reference samples was also verified on samples with an oxide layer of known composition, which were prepared by sputter deposition. The composition of the sputtered oxide layers was analysed by the weight-gain method and Rutherford backscattering without the use of standard reference materials (SRM), and the results were then compared with those obtained by AES depth profile analysis.

  16. Manganese- and iron-dependent marine methane oxidation.

    PubMed

    Beal, Emily J; House, Christopher H; Orphan, Victoria J

    2009-07-10

    Anaerobic methanotrophs help regulate Earth's climate and may have been an important part of the microbial ecosystem on the early Earth. The anaerobic oxidation of methane (AOM) is often thought of as a sulfate-dependent process, despite the fact that other electron acceptors are more energetically favorable. Here, we show that microorganisms from marine methane-seep sediment in the Eel River Basin in California are capable of using manganese (birnessite) and iron (ferrihydrite) to oxidize methane, revealing that marine AOM is coupled, either directly or indirectly, to a larger variety of oxidants than previously thought. Large amounts of manganese and iron are provided to oceans from rivers, indicating that manganese- and iron-dependent AOM have the potential to be globally important.

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

    NASA Astrophysics Data System (ADS)

    Radu, T.; Iacovita, C.; Benea, D.; Turcu, R.

    2017-05-01

    We report X-ray photoelectron spectroscopy (XPS) results on iron oxide magnetic nanoparticle (Fe3O4) synthesized using solvothermal reduction in the presence of polyethylene glycol. The magnetite obtained was employed as precursor for the synthesis of γ-Fe2O3 (by oxygen dissociation) which in turn was transformed into α-Fe2O3. 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.

  18. Virus-Templated Near-Amorphous Iron Oxide Nanotubes.

    PubMed

    Shah, Sachin N; Khan, Abid A; Espinosa, Ana; Garcia, Miguel A; Nuansing, Wiwat; Ungureanu, Mariana; Heddle, Jonathan G; Chuvilin, Andrey L; Wege, Christina; Bittner, Alexander M

    2016-06-14

    We present a simple synthesis of iron oxide nanotubes, grown under very mild conditions from a solution containing Fe(II) and Fe(III), on rod-shaped tobacco mosaic virus templates. Their well-defined shape and surface chemistry suggest that these robust bionanoparticles are a versatile platform for synthesis of small, thin mineral tubes, which was achieved efficiently. Various characterization tools were used to explore the iron oxide in detail: Electron microscopy (SEM, TEM), magnetometry (SQUID-VSM), diffraction (XRD, TEM-SAED), electron spectroscopies (EELS, EDX, XPS), and X-ray absorption (XANES with EXAFS analysis). They allowed determination of the structure, crystallinity, magnetic properties, and composition of the tubes. The protein surface of the viral templates was crucial to nucleate iron oxide, exhibiting analogies to biomineralization in natural compartments such as ferritin cages.

  19. Potential Toxicity and Underlying Mechanisms Associated with Pulmonary Exposure to Iron Oxide Nanoparticles: Conflicting Literature and Unclear Risk.

    PubMed

    Kornberg, Tiffany G; Stueckle, Todd A; Antonini, James A; Rojanasakul, Yon; Castranova, Vincent; Yang, Yong; Wang, Liying

    2017-10-06

    Fine/micron-sized iron oxide particulates are incidentally released from a number of industrial processes, including iron ore mining, steel processing, welding, and pyrite production. Some research suggests that occupational exposure to these particulates is linked to an increased risk of adverse respiratory outcomes, whereas other studies suggest that iron oxide is biologically benign. Iron oxide nanoparticles (IONPs), which are less than 100 nm in diameter, have recently surged in use as components of novel drug delivery systems, unique imaging protocols, as environmental catalysts, and for incorporation into thermoplastics. However, the adverse outcomes associated with occupational exposure to IONPs remain relatively unknown. Relevant in vivo studies suggest that pulmonary exposure to IONPs may induce inflammation, pulmonary fibrosis, genotoxicity, and extra-pulmonary effects. This correlates well with in vitro studies that utilize relevant dose, cell type(s), and meaningful end points. A majority of these adverse outcomes are attributed to increased oxidative stress, most likely caused by particle internalization, dissolution, release of free iron ions, and disruption of iron homeostasis. However, because the overall toxicity profile of IONPs is not well understood, it is difficult to set safe exposure limit recommendations that would be adequate for the protection of at-risk workers. This review article will focus on known risks following IONPs exposure supported by human, animal, and cell culture-based studies, the potential challenges intrinsic to IONPs toxicity assessment, and how these may contribute to the poorly characterized IONPs toxicity profile.

  20. Arsenate adsorption onto iron oxide amended rice husk char.

    PubMed

    Cope, Christopher O; Webster, Damon S; Sabatini, David A

    2014-08-01

    In this study, rice husks were charred at 550 °C in a partially sealed ceramic vessel for 30minutes to create a high specific surface area (SSA) rice husk char (RHC). The RHC was then amended with iron oxides using dissolved ferric nitrate, Fe(NO3)3⋅9H2O, to provide a surface chemistry conducive to arsenic adsorption. The 550 °C iron oxide amended rice husk char's (550 IOA-RHC's) SSA was nearly 2.5 orders of magnitude higher and the arsenate adsorptive level was nearly 2 orders of magnitude higher than those reported for iron oxide amended sand, thus indicating a positive relationship between post-amendment SSA and arsenate adsorptive levels. Rice husks were then charred at temperatures ranging from 450 °C to 1050 °C to create an even higher SSA material, which might further increase arsenate adsorptive levels. The 950 °C RHC was chosen for amendment due to its high SSA and feasibility of being produced in the field. Once amended, the 950 °C iron oxide amended rice husk char (950 IOA-RHC) improved the arsenate adsorption capacity by thus confirming a positive relationship, though not a linear relationship, between post-amendment SSA and arsenic adsorptive capacity. Further study demonstrated that post-amendment mesoporous volume and mesoporous surface area appear to be better indicators of arsenic adsorptive capacity than SSA or iron content.

  1. Recovery of iron oxide from coal fly ash

    DOEpatents

    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.

  2. Electrolytic photodissociation of chemical compounds by iron oxide electrodes

    DOEpatents

    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.

  3. Electrolytic photodissociation of chemical compounds by iron oxide photochemical diodes

    DOEpatents

    Somorjai, Gabor A.; Leygraf, Christofer H.

    1985-01-01

    Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor photochemical diode having visible light as its sole source of energy. The photochemical 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.

  4. Structural changes in iron-cobalt oxide nanosystems

    NASA Astrophysics Data System (ADS)

    Nishchev, K. N.; Golub'ev, M. A.; Maksimov, Yu. V.; Beglov, V. I.; Kyashkin, V. M.; Panov, A. A.

    2015-05-01

    The structure of binary iron-cobalt oxide nanosystems—precursors of bimetallic catalysts—is studied by Mössbauer spectroscopy, X-ray diffraction, and small-angle X-ray scattering. The oxide system under study represents a promising material for creating new metallic nanocatalysts for ammonia synthesis. The structural evolution in the composition range 100Fe/0Co-5Fe/95Co is found to correspond to the transition from fine-grained α-Fe2O3 to mixed iron-cobalt spinels of various compositions and degrees of dispersity.

  5. Electrolytic photodissociation of chemical compounds by iron oxide electrodes

    SciTech Connect

    Somorjai, G.A.; Leygraf, C.H.

    1984-07-17

    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.

  6. Multifunctional superparamagnetic iron oxide nanoparticles: promising tools in cancer theranostics.

    PubMed

    Santhosh, Poornima Budime; Ulrih, Nataša Poklar

    2013-08-09

    Iron-oxide nanoparticles of small dimensions that have superparamagnetic properties show immense potential to revolutionize the future of cancer theranostics, the combinatorial diagnosis and therapeutic approach towards cancer. Superparamagnetic iron-oxide nanoparticles (SPIONs) have unique magnetic properties, due to which they show excellent tumor-targeting efficiency, and this paves the way for effective personalized cancer treatment. The aim of this review is to focus on the ability of SPIONs to perform multiple roles in the field of cancer biology, such as in diagnosis, monitoring, targeting and therapy. Also, other topics are discussed, including the synthesis of SPIONs, the challenges and recent advances.

  7. Magnetic fluid hyperthermia: focus on superparamagnetic iron oxide nanoparticles.

    PubMed

    Laurent, Sophie; Dutz, Silvio; Häfeli, Urs O; Mahmoudi, Morteza

    2011-08-10

    Due to their unique magnetic properties, excellent biocompatibility as well as multi-purpose biomedical potential (e.g., applications in cancer therapy and general drug delivery), superparamagnetic iron oxide nanoparticles (SPIONs) are attracting increasing attention in both pharmaceutical and industrial communities. The precise control of the physiochemical properties of these magnetic systems is crucial for hyperthermia applications, as the induced heat is highly dependent on these properties. In this review, the limitations and recent advances in the development of superparamagnetic iron oxide nanoparticles for hyperthermia are presented.

  8. Multifunctional Iron Oxide Nanoparticles for Diagnostics, Therapy and Macromolecule Delivery

    PubMed Central

    Yen, Swee Kuan; Padmanabhan, Parasuraman; Selvan, Subramanian Tamil

    2013-01-01

    In recent years, multifunctional nanoparticles (NPs) consisting of either metal (e.g. Au), or magnetic NP (e.g. iron oxide) with other fluorescent components such as quantum dots (QDs) or organic dyes have been emerging as versatile candidate systems for cancer diagnosis, therapy, and macromolecule delivery such as micro ribonucleic acid (microRNA). This review intends to highlight the recent advances in the synthesis and application of multifunctional NPs (mainly iron oxide) in theranostics, an area used to combine therapeutics and diagnostics. The recent applications of NPs in miRNA delivery are also reviewed. PMID:24396508

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

    EPA Science Inventory

    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...

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

    EPA Science Inventory

    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...

  11. Size-dependent magnetic properties of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Patsula, Vitalii; Moskvin, Maksym; Dutz, Silvio; Horák, Daniel

    2016-01-01

    Uniform iron oxide nanoparticles in the size range from 10 to 24 nm and polydisperse 14 nm iron oxide particles were prepared by thermal decomposition of Fe(III) carboxylates in the presence of oleic acid and co-precipitation of Fe(II) and Fe(III) chlorides by ammonium hydroxide followed by oxidation, respectively. While the first method produced hydrophobic oleic acid coated particles, the second one formed hydrophilic, but uncoated, nanoparticles. To make the iron oxide particles water dispersible and colloidally stable, their surface was modified with poly(ethylene glycol) and sucrose, respectively. Size and size distribution of the nanoparticles was determined by transmission electron microscopy, dynamic light scattering and X-ray diffraction. Surface of the PEG-functionalized and sucrose-modified iron oxide particles was characterized by Fourier transform infrared (FT-IR) and Raman spectroscopy and thermogravimetric analysis (TGA). Magnetic properties were measured by means of vibration sample magnetometry and specific absorption rate in alternating magnetic fields was determined calorimetrically. It was found, that larger ferrimagnetic particles showed higher heating performance than smaller superparamagnetic ones. In the transition range between superparamagnetism and ferrimagnetism, samples with a broader size distribution provided higher heating power than narrow size distributed particles of comparable mean size. Here presented particles showed promising properties for a possible application in magnetic hyperthermia.

  12. Iron oxides, dissolved silica, and regulation of marine phosphate concentration

    NASA Astrophysics Data System (ADS)

    Planavsky, N.; Reinhard, C.; Lyons, T.

    2008-12-01

    Phosphorous concentrations in iron oxide-rich sediments reflect orthophosphate levels in the water column from which iron oxides precipitated. Sediment P/Fe ratios are also strongly influenced by the concentrations of dissolved species that inhibit orthophosphate-to-ferrihydrite sorption, most notably silica. It may, therefore, be possible to use P/Fe ratios in iron oxide-rich sediments to estimate past dissolved P concentrations, if one considers the evolution of the silica cycle. A compilation of Fe and P data in iron oxide-rich sediments through time reveals an increase in P/Fe ratios after the Jurassic. We propose that this trend indicates evolution of the iron-oxide phosphate removal mechanism caused by decreasing levels of sorption inhibition by dissolved silica. The large difference in P/Fe ratios in Cenozoic versus older iron-oxide rich sediments can be linked with Si drawdown caused by the proliferation of siliceous plankton in the Cretaceous. There is also a late Mesozoic or Cenozoic increase in V/Fe ratios, which provides additional evidence for lower ferrihydrite anion sorption efficiency prior to diatom radiation. P/Fe ratios in iron oxide-rich sediments from the early and middle Phanerozoic are comparable to the ratios in iron formations previously presented as evidence for an early Precambrian phosphate crisis (Bjerrum and Canfield, 2002, Nature, 417:159-162). Given the compelling evidence for higher Si concentrations in the Precambrian compared to the Phanerozoic and dissolved P concentrations comparable to modern levels throughout the Phanerozoic, the presented trend of P/Fe ratios suggests dissolved P concentrations were higher in Precambrian than Phanerozoic oceans. High dissolved P levels in the Precambrian may have been linked to inhibited carbonate fluorapatite (CFA) formation as a result of persistently high levels of carbonate supersaturation. Carbonate ion substitution into CFA scales with the ambient carbonate ion activity and increases

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

    EPA Science Inventory

    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...

  14. Nitric oxide ameliorates the damaging effects of oxidative stress induced by iron deficiency in cyanobacterium Anabaena 7120.

    PubMed

    Kaushik, Manish Singh; Srivastava, Meenakshi; Srivastava, Alka; Singh, Anumeha; Mishra, Arun Kumar

    2016-11-01

    In cyanobacterium Anabaena 7120, iron deficiency leads to oxidative stress with unavoidable consequences. Nitric oxide reduces pigment damage and supported the growth of Anabaena 7120 in iron-deficient conditions. Elevation in nitric oxide accumulation and reduced superoxide radical production justified the role of nitric oxide in alleviating oxidative stress in iron deficiency. Increased activities of antioxidative enzymes and higher levels of ROS scavengers (ascorbate, glutathione and thiol) in iron deficiency were also observed in the presence of nitric oxide. Nitric oxide also supported the membrane integrity of Anabaena cells and reduces protein and DNA damage caused by oxidative stress induced by iron deficiency. Results suggested that nitric oxide alleviates the damaging effects of oxidative stress induced by iron deficiency in cyanobacterium Anabaena 7120.

  15. Elevated exhaled nitric oxide in anaphylaxis with respiratory symptoms.

    PubMed

    Nakamura, Yoichi; Hashiba, Yoko; Endo, Jyunji; Furuie, Masashi; Isozaki, Atsushi; Yagi, Kei-ichi

    2015-10-01

    Anaphylaxis is a serious type I allergic reaction that occurs suddenly and can result in death, but it is sometimes difficult to differentiate from other diseases, and physicians must rely on symptoms alone for its diagnosis. Meanwhile, fractional exhaled nitric oxide (FeNO) concentration, used in assessing airway inflammation in bronchial asthma, is known to be affected by atopic disposition. The possible role of FeNO measurements was evaluated in patients with anaphylaxis. FeNO was measured in 52 adult patients (17-78 years old, median age 41.5 years) in whom anaphylaxis occurred. These measurements were made within 24 h after onset and after about one month when the patients were symptom-free. In some of these patients, FeNO was measured a third time, two months or more after onset. The FeNO level in the 52 patients was not significantly different in measurement made within 24 h of onset of anaphylaxis and after one month. However, excluding 9 patients who also had asthma history, the FeNO level in the remaining 43 patients decreased significantly from within 24 h of onset (36.7 ± 27.5 ppb) to one month later (28.8 ± 19.5 ppb). Of these 43 patients, this phenomenon was evident in a group that had respiratory symptoms (31 patients), but it was not seen in a group that did not have respiratory symptoms (12 patients). Elevation of FeNO was related to respiratory symptoms observed in anaphylactic patients without asthma. Although the mechanism of increased FeNO level is unclear, its usefulness for diagnosis of anaphylaxis must be examined in prospective studies. Copyright © 2015 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

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

    PubMed

    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.

  17. Deposition rates of oxidized iron on Mars

    NASA Technical Reports Server (NTRS)

    Burns, R. G.

    1993-01-01

    The reddened oxidized surface of Mars is indicative of temporal interactions between the Martian atmosphere and its surface. During the evolution of the Martian regolith, primary ferromagnesian silicate and sulfide minerals in basaltic rocks apparently have been oxidized to secondary ferric-bearing assemblages. To evaluate how and when such oxidized deposits were formed on Mars, information about the mechanisms and rates of chemical weathering of Fe(2+)-bearing minerals has been determined. In this paper, mechanisms and rates of deposition of ferric oxide phases on the Martian surface are discussed.

  18. Magnetic resonance imaging contrast of iron oxide nanoparticles developed for hyperthermia is dominated by iron content

    PubMed Central

    Wabler, Michele; Zhu, Wenlian; Hedayati, Mohammad; Attaluri, Anilchandra; Zhou, Haoming; Mihalic, Jana; Geyh, Alison; DeWeese, Theodore L.; Ivkov, Robert; Artemov, Dmitri

    2015-01-01

    Purpose Magnetic iron oxide nanoparticles (MNPs) are used as contrast agents for magnetic resonance imaging (MRI) and hyperthermia for cancer treatment. The relationship between MRI signal intensity and cellular iron concentration for many new formulations, particularly MNPs having magnetic properties designed for heating in hyperthermia, is lacking. In this study, we examine the correlation between MRI T2 relaxation time and iron content in cancer cells loaded with various MNP formulations. Materials and methods Human prostate carcinoma DU-145 cells were loaded with starch-coated bionised nanoferrite (BNF), iron oxide (Nanomag® D-SPIO), Feridex™, and dextran-coated Johns Hopkins University (JHU) particles at a target concentration of 50 pg Fe/cell using poly-D-lysine transfection reagent. T2-weighted MRI of serial dilutions of these labelled cells was performed at 9.4 T and iron content quantification was performed using inductively coupled plasma mass spectrometry (ICP-MS). Clonogenic assay was used to characterise cytotoxicity. Results No cytotoxicity was observed at twice the target intracellular iron concentration (~100 pg Fe/cell). ICP-MS revealed highest iron uptake efficiency with BNF and JHU particles, followed by Feridex and Nanomag-D-SPIO, respectively. Imaging data showed a linear correlation between increased intracellular iron concentration and decreased T2 times, with no apparent correlation among MNP magnetic properties. Conclusions This study demonstrates that for the range of nanoparticle concentrations internalised by cancer cells the signal intensity of T2-weighted MRI correlates closely with absolute iron concentration associated with the cells. This correlation may benefit applications for cell-based cancer imaging and therapy including nanoparticle-mediated drug delivery and hyperthermia. PMID:24773041

  19. Iron as a catalyst of human low-density lipoprotein oxidation: Critical factors involved in its oxidant properties.

    PubMed

    Lapenna, Domenico; Ciofani, Giuliano; Obletter, Gabriele

    2017-05-01

    Iron-induced human LDL oxidation, which is relevant to atherosclerosis, has not yet been properly investigated. We addressed such issue using iron(II) and (III) basically in the presence of phosphates, which are present in vivo and influence iron oxidative properties, at pH 4.5 and 7.4, representative, respectively, of the lysosomal and plasma environment. In 10mM phosphate buffered saline (PBS), iron(II) induces substantial LDL oxidation at pH 4.5 at low micromolar concentrations, while at pH 7.4 has low oxidative effects; iron(III) promotes small LDL oxidation only at pH 4.5. In 10mM sodium acetate/NaCl buffer, pH 4.5, iron-induced LDL oxidation is far higher than in PBS, highlighting the relevance of phosphates in the inhibitory modulation of iron-induced LDL oxidation. LDL oxidation is related to iron binding to the protein and lipid moiety of LDL, and requires the presence of iron(II) bound to LDL together with iron(III). Chemical modification of LDL carboxyl groups, which could bind iron especially at pH 4.5, decreases significantly iron binding to LDL and iron-induced LDL oxidation. Hydroxyl radical scavengers are ineffective on iron-induced LDL oxidation, which is inhibited by metal chelation, scavengers of alkoxyl/peroxyl radicals, or removal of LDL lipid hydroperoxides (LOOH). Overall, substantial human LDL oxidation is induced LOOH-dependently by iron(II) at pH 4.5 even in the presence of phosphates, suggesting the occurrence of iron(II)-induced LDL oxidation in vivo within lysosomes, where pH is about 4.5, iron(II) and phosphates coexist, plasma with its antioxidants is absent, and glutathione peroxidase is poorly expressed resulting in LOOH accumulation.

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

    PubMed Central

    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

  1. Distribution Behavior of Phosphorus and Metallization of Iron Oxide in Carbothermic Reduction of High-Phosphorus Iron Ore

    NASA Astrophysics Data System (ADS)

    Cha, Ji-Whoe; Kim, Dong-Yuk; Jung, Sung-Mo

    2015-10-01

    Distribution behavior of phosphorus and metallization of iron ore in the carbothermic reduction of high-phosphorus iron ore were investigated. Reduction degree of the iron oxide was evaluated by quadruple mass spectrometry connected to thermogravimetric analysis. The distribution of some elements including phosphorus was examined by electron probe micro-analyzer mapping analyses. The reduction behavior of high-phosphorus iron ore was evaluated as a function of reduction temperature, C/O molar ratio, and CaO addition. High reduction temperature accelerated the reduction of both iron oxide and hydroxylapatite, and high C/O molar ratio also promotes both of them. Those were contradictory to the targets of higher reduction degree of iron oxide and of lower one of hydroxylapatite. It was confirmed that appropriate amount of CaO addition could enhance the reduction of iron oxide, and regulate the reduction of hydroxylapatite.

  2. Iron Partitioning and Oxidation State in Earth's Lower Mantle

    NASA Astrophysics Data System (ADS)

    Piet, H.; Badro, J.; Nabiei, F.; Dennenwaldt, T.; Shim, S. H. D.; Cantoni, M.; Hébert, C.; Gillet, P.

    2015-12-01

    Valence state and concentrations of iron in lower mantle phases have strong effects on their chemical and physical properties. Experimental studies have reported stark differences in iron partitioning between bridgmanite (Brg) and ferropericlase (Fp) for San Carlos olivine [1] and pyrolite [2] systems. We recently performed experiments at lower mantle conditions for an Al-rich olivine system [3] and observed an iron enrichment of the silicate phase very similar to that in pyrolite. Mössbauer studies [4] have shown that in the presence of aluminum non negligible amounts of Fe3+ could be incorporated in bridgmanite explaining the observed iron enrichment. Non negligible amounts of Fe3+ in the lower mantle could influence transport properties of the phases [5]. The evaluation of ferrous and ferric iron concentrations in lower mantle mineral assemblages is then key to a thorough understanding of geophysical observations and associated mantle dynamics. We used electron energy loss spectroscopy technique to quantify the proportions of Fe2+ and Fe3+ iron in Brg and Fp phases previously synthesized from Al-rich olivine composition [3]. The oxidation state of iron in the lower mantle will be discussed as well as ensuing implications on transport properties for relevant lower mantle compositions. References [1] Sakai et al., 2009 [2] Prescher et al., 2014 [3] Piet et al., submitted [4] McCammon et al., 1996 [5] Xu et al., 1998

  3. Facile Synthesis of Iron Oxide/Graphene Nanocomposites Using Liquid Phase Plasma Method.

    PubMed

    Lee, H; Park, Y K; Kim, S J; Kim, B J; An, K H; Kim, B H; Jung, S C

    2016-05-01

    Liquid phase plasma (LPP) method was applied, for the first time, to the impregnation of iron oxide nanoparticles onto graphene sheet. Iron oxide nanoparticles with the size of 50 nm were precipitated with uniform dispersion on the surface of graphene sheet. The amount of iron oxide nanoparticles precipitated on graphene sheets increased with increasing LPP process times. The XPS, Raman and EDX analyses showed that the iron oxide/graphene composites synthesized by the LPP process.

  4. Uptake and metabolism of iron oxide nanoparticles in brain cells.

    PubMed

    Petters, Charlotte; Irrsack, Ellen; Koch, Michael; Dringen, Ralf

    2014-09-01

    Magnetic iron oxide nanoparticles (IONPs) are used for various applications in biomedicine, for example as contrast agents in magnetic resonance imaging, for cell tracking and for anti-tumor treatment. However, IONPs are also known for their toxic effects on cells and tissues which are at least in part caused by iron-mediated radical formation and oxidative stress. The potential toxicity of IONPs is especially important concerning the use of IONPs for neurobiological applications as alterations in brain iron homeostasis are strongly connected with human neurodegenerative diseases. Since IONPs are able to enter the brain, potential adverse consequences of an exposure of brain cells to IONPs have to be considered. This article describes the pathways that allow IONPs to enter the brain and summarizes the current knowledge on the uptake, the metabolism and the toxicity of IONPs for the different types of brain cells in vitro and in vivo.

  5. From iron coordination compounds to metal oxide nanoparticles.

    PubMed

    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, [Fe2(III)Fe(II)O(CH3COO)6(H2O)3]·2H2O (FeAc1), μ3-oxo trinuclear iron(III) acetate, [Fe3O(CH3COO)6(H2O)3]NO3∙4H2O (FeAc2), iron furoate, [Fe3O(C4H3OCOO)6(CH3OH)3]NO3∙2CH3OH (FeF), iron chromium furoate, FeCr2O(C4H3OCOO)6(CH3OH)3]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.

  6. From iron coordination compounds to metal oxide nanoparticles

    PubMed Central

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

    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, [Fe2 IIIFeIIO(CH3COO)6(H2O)3]·2H2O (FeAc1), μ3-oxo trinuclear iron(III) acetate, [Fe3O(CH3COO)6(H2O)3]NO3∙4H2O (FeAc2), iron furoate, [Fe3O(C4H3OCOO)6(CH3OH)3]NO3∙2CH3OH (FeF), iron chromium furoate, FeCr2O(C4H3OCOO)6(CH3OH)3]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. PMID:28144555

  7. Behavior of iron aluminides in oxidizing and sulfidizing environments

    SciTech Connect

    Tortorelli, P.F.; DeVan, J.H.; DiStefano, J.R.

    1989-01-01

    To date, use of iron aluminides based on Fe/sub 3/Al (less than or equal to30 at. % Al) or FeAl (30--50 at. % Al) for structural applications has been limited by their low ductility and poor fracture toughness at room temperature and inadequate strength above 600/degree/C. However, in recent years, a renewed effort has been devoted to the development of ductile iron aluminides with increased strength, particularly in view of their good potential for use in hostile environments. While it is expected that such aluminides will be able to form oxide scales for corrosion protection in oxidizing high temperature environments, resistance to degradation in oxidizing salt or oxidizing/sulfidizing gas environments has not been adequately addressed as a function of compositional and microstructural changes. This paper reviews and extends results for iron aluminides exposed to an oxidizing/sulfidizing gas and presents the first data for corrosion of this class of materials by an aggressive oxidizing molten nitrate salt of 48.5NaNO/sub 3/--50.5KNO/sub 3/--1Na/sub 2/O/sub 2/. 14 refs., 11 figs.

  8. Oxidation resistant iron and nickel alloys for high temperature use

    NASA Technical Reports Server (NTRS)

    Hill, V. L.; Misra, S. K.; Wheaton, H. L.

    1970-01-01

    Iron-base and nickel-base alloys exhibit good oxidation resistance and improved ductility with addition of small amounts of yttrium, tantalum /or hafnium/, and thorium. They can be used in applications above the operating temperatures of the superalloys, if high strength materials are not required.

  9. New Perspectives on Biomedical Applications of Iron Oxide Nanoparticles.

    PubMed

    Magro, Massimiliano; Baratella, Davide; Bonaiuto, Emanuela; de Almeida Roger, Jessica; Vianello, Fabio

    2017-06-16

    Iron oxide nanomaterials are considered promising tools for improved therapeutic efficacy and diagnostic applications in biomedicine. Accordingly, engineered iron oxide nanomaterials are increasingly proposed in biomedicine, and the interdisciplinary researches involving physics, chemistry, biology (nanotechnology) and medicine have led to exciting developments in the last decades. The progresses of the development of magnetic nanoparticles with tailored physico-chemical and surface properties produced a variety of clinically relevant applications, spanning from magnetic resonance imaging (MRI), drug delivery, magnetic hyperthermia, to in vitro diagnostics. Notwithstanding the well-known conventional synthetic procedures and their wide use, recent advances in the synthetic methods open the door to new generations of naked iron oxide nanoparticles possessing peculiar surface chemistries, suitable for other competitive biomedical applications. New abilities to rationally manipulate iron oxides and their physical, chemical, and biological properties, allow the emersion of additional possibilities for designing novel nanomaterials for theranostic applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  10. 40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cobalt iron manganese oxide... Significant New Uses for Specific Chemical Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid... substance identified generically as cobalt iron manganese oxide, carboxylic acid-modified (PMN P-12-35) is...

  11. Formation of water-soluble iron oxide nanoparticles derived from iron storage protein.

    PubMed

    Tominaga, Masato; Han, Li; Wang, Lingyan; Maye, Mathew M; Luo, Jin; Kariuki, Nancy; Zhong, Chuan-Jian

    2004-09-01

    This paper reports novel findings of an investigation of the formation of water-soluble iron oxide nanoparticles from iron-storage protein ferritin. The strategy couples thermal removal of the protein shell on a planar substrate and subsequent sonication in aqueous solution under controlled temperature. Advantages of using ferritin as a precursor include well-defined core size, core composition, water-solubility and processibility. The formation of the nanoparticles was characterized using TEM, UV-Vis and FTIR techniques. Iron oxide nanoparticles in the size range of 5-20 nm diameters were produced. In addition to thermal treatment conditions, the sonication temperature of the nanoparticles in water was found to play an important role in determining the resulting particle size. This simple and effective route has important implications to the design of composite nanoparticles for potential magnetic, catalytic, biomedical sensing and other nanotechnological applications.

  12. Iron Kinetics and Evolution of Microbial Populations in Low-pH, Ferrous Iron-Oxidizing Bioreactors.

    PubMed

    Jones, Rose M; Johnson, D Barrie

    2016-08-02

    Iron-rich, acidic wastewaters are commonplace pollutants associated with metal and coal mining. Continuous-flow bioreactors were commissioned and tested for their capacities to oxidize ferrous iron in synthetic and actual acid mine drainage waters using (initially) pure cultures of the recently described acidophilic, iron-oxidizing heterotrophic bacterium Acidithrix ferrooxidans grown in the presence of glucose and yeast extract. The bioreactors became rapidly colonized by this bacterium, which formed macroscopic streamer growths in the flowing waters. Over 97% of ferrous iron in pH 2.0-2.2 synthetic mine water was oxidized (at up to 225 mg L(-1) h(-1)) at dilution rates (D) of 0.6 h(-1). Rates of iron oxidation decreased with pH but were still significant, with influent liquors as low as pH 1.37. When fed with actual mine water, >90% of ferrous iron was oxidized at D values of 0.4 h(-1), and microbial communities within the bioreactors changed over time, with Atx. ferrooxidans becoming increasingly displaced by the autotrophic iron-oxidizing acidophiles Ferrovum myxofaciens, Acidithiobacillus ferrivorans, and Leptospirillum ferrooxidans (which were all indigenous to the mine water), although this did not have a negative impact on net ferrous-iron oxidation. The results confirmed the potential of using a heterotrophic acidophile to facilitate the rapid commissioning of iron-oxidizing bioreactors and illustrated how microbial communities within them can evolve without compromising the performances of the bioreactors.

  13. Oxidative stress, HDL functionality and effects of intravenous iron administration in women with iron deficiency anemia.

    PubMed

    Meroño, Tomás; Dauteuille, Carolane; Tetzlaff, Walter; Martín, Maximiliano; Botta, Eliana; Lhomme, Marie; Saez, María Soledad; Sorroche, Patricia; Boero, Laura; Arbelbide, Jorge; Chapman, M John; Kontush, Anatol; Brites, Fernando

    2017-04-01

    Iron deficiency anemia (IDA) affects around 20-30% of adults worldwide. An association between IDA and cardiovascular disease (CVD) has been reported. Oxidative stress, inflammation and low concentration of high-density lipoproteins (HDL) were implicated on endothelial dysfunction and CVD in IDA. We studied the effects of iron deficiency and of an intravenous iron administration on oxidative stress and HDL characteristics in IDA women. Two studies in IDA women are presented: a case-control study, including 18 patients and 18 age-matched healthy women, and a follow-up study 72hr after the administration of intravenous iron (n = 16). Lipids, malondialdehyde, cholesteryl ester transfer protein (CETP), paraoxonase-1 (PON-1) and HDL chemical composition and functionality (cholesterol efflux and antioxidative activity) were measured. Cell cholesterol efflux from iron-deficient macrophages to a reference HDL was also evaluated. IDA patients showed higher triglycerides and CETP activity and lower HDL-C than controls (all p < 0.001). HDL particles from IDA patients showed higher triglyceride content (+30%,p < 0.05) and lower antioxidative capacity (-23%,p < 0.05). Although HDL-mediated cholesterol efflux was similar between the patients and controls, iron deficiency provoked a significant reduction in macrophage cholesterol efflux (-25%,p < 0.05). Arylesterase activity of PON-1 was significantly lower in IDA patients than controls (-16%,p < 0.05). The intravenous administration of iron was associated with a decrease in malondialdehyde levels and an increase in arylesterase activity of PON-1 (-22% and +18%, respectively, p < 0.05). IDA is associated with oxidative stress and functionally deficient HDL particles. It remains to be determined if such alterations suffice to impair endothelial function in IDA. Copyright © 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  14. Simultaneous reductive dissolution of iron oxide and oxidation of iodide in ice.

    NASA Astrophysics Data System (ADS)

    Kim, Kitae; Choi, Wonyong

    2015-04-01

    Iron is an important trace element controlling the metabolism and growth of all kinds of living species. Especially, the bio-availability of iron has been regarded as the limiting factor for primary productivity in HNLC (High Nutrients Low Chlorophyll) regions including Southern ocean. The dissolution of iron oxide provides enhanced the bio-availability of iron for phytoplankton growth. The halogen chemistry in polar regions is related to various important environmental processes such as Antarctic Ozone Depletion Event(ODE), mercury depletion, oxidative processes in atmosphere, and the formation of CCN (Cloud Condensation Nuclei). In this study, we investigated the reductive dissolution of iron oxide particles to produce Fe(II)aq and simultaneous oxidation of I- (iodide) to I3- (tri-iodide) in ice phase under UV irradiation or dark condition. The reductive generation of Fe(II)aq from iron oxides and oxidation of iodide to I3- were negligible in water but significantly accelerated in frozen solution both in the presence and absence of light. The enhanced reductive generation of Fe(II)aq and oxidative formation of I3- in ice were observed regardless of the various types of iron oxides [hematite (α-Fe2O3) maghemite (γ- Fe2O3), goethite (α-FeOOH), lepidocrocite (γ-FeOOH) and, magnetite (Fe3O4)]. We explained that the enhanced redox production of Fe(II)aq and I3- in ice is contributed to the freeze concentration of iodides, protons, and dissolved oxygen in the unfrozen solution. When the concentration of both iodides and protons were raised by 10-fold each, the formation of Fe(II)aq in water under UV irradiation was approached to those in ice. The outdoor experiments were carried out under ambient solar radiation in winter season of mid-latitude (Pohang, Korea: 36°N latitude) and also confirmed that the production of Fe(II)aq via reductive dissolution of iron oxide and I3- generation via I- oxidation were enhanced in frozen solution. These results suggest that iron

  15. Iron oxide nanotubes synthesized via template-based electrodeposition

    NASA Astrophysics Data System (ADS)

    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

  16. Oxidation, carburization and/or sulfidation resistant iron aluminide alloy

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    2003-08-19

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or Zro.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B. .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  17. The Molecular Mechanism of Iron(III) Oxide Nucleation.

    PubMed

    Scheck, Johanna; Wu, Baohu; Drechsler, Markus; Rosenberg, Rose; Van Driessche, Alexander E S; Stawski, Tomasz M; Gebauer, Denis

    2016-08-18

    A molecular understanding of the formation of solid phases from solution would be beneficial for various scientific fields. However, nucleation pathways are still not fully understood, whereby the case of iron (oxyhydr)oxides poses a prime example. We show that in the prenucleation regime, thermodynamically stable solute species up to a few nanometers in size are observed, which meet the definition of prenucleation clusters. Nucleation then is not governed by a critical size, but rather by the dynamics of the clusters that are forming at the distinct nucleation stages, based on the chemistry of the linkages within the clusters. This resolves a longstanding debate in the field of iron oxide nucleation, and the results may generally apply to oxides forming via hydrolysis and condensation. The (molecular) understanding of the chemical basis of phase separation is paramount for, e.g., tailoring size, shape and structure of novel nanocrystalline materials.

  18. Deep reduction behavior of iron oxide and its effect on direct CO oxidation

    NASA Astrophysics Data System (ADS)

    Dong, Changqing; Liu, Xinglei; Qin, Wu; Lu, Qiang; Wang, Xiaoqiang; Shi, Simo; Yang, Yongping

    2012-01-01

    Reduction of metal oxide oxygen carrier has been attractive for direct CO oxidation and CO2 separation. To investigate the reduction behaviors of iron oxide prepared by supporting Fe2O3 on γ-Al2O3 and its effect on CO oxidation, fluidized-bed combustion experiments, thermogravimetric analyzer (TGA) experiments, and density functional theory (DFT) calculations were carried out. Gas yield (γCO2) increases significantly with the increase of temperature from 693 K to 1203 K, while carbon deposition decreases with the increase of temperature from 743 K to 1203 K, where temperature is a very important factor for CO oxidation by iron oxide. Further, it were quantitatively detected that the interaction between CO and Fe2O3, breakage of O-Fe bonds and formation of new C-O bonds, and effect of reduction degree were quantitatively detected. Based on adsorptions under different temperatures and reducing processes from Fe3+ into Fe2+, Fe+ and then into Fe, it was found that Fe2+ → Fe+ was the reaction-controlling step and the high oxidation state of iron is active for CO oxidation, where efficient partial reduction of Fe2O3 into FeO rather than complete reduction into iron may be more energy-saving for CO oxidation.

  19. HMOX1 as a marker of iron excess-induced adipose tissue dysfunction, affecting glucose uptake and respiratory capacity in human adipocytes.

    PubMed

    Moreno-Navarrete, José María; Ortega, Francisco; Rodríguez, Amaia; Latorre, Jèssica; Becerril, Sara; Sabater-Masdeu, Mònica; Ricart, Wifredo; Frühbeck, Gema; Fernández-Real, José Manuel

    2017-05-01

    Iron excess in adipose tissue is known to promote adipose tissue dysfunction. Here, we aimed to investigate the possible role of haem oxygenase 1 (HMOX1) in iron excess-induced adipose tissue dysfunction. Cross-sectionally, HMOX1 gene expression in subcutaneous and visceral adipose tissue was analysed in two independent cohorts (n = 234 and 40) in relation to obesity. We also evaluated the impact of weight loss (n = 21), weight gain (in rats, n = 20) on HMOX1 mRNA; HMOX1 mRNA levels during human adipocyte differentiation; the effects of inflammation and iron on adipocyte HMOX1; and the effects of HMOX1-induced activity on adipocyte mitochondrial respiratory function, glucose uptake and adipogenesis. Adipose tissue HMOX1 was increased in obese participants (p = 0.01) and positively associated with obesity-related metabolic disturbances, and markers of iron accumulation, inflammation and oxidative stress (p < 0.01). HMOX1 was negatively correlated with mRNAs related to mitochondrial biogenesis, the insulin signalling pathway and adipogenesis (p < 0.01). These associations were replicated in an independent cohort. Bariatric surgery-induced weight loss led to reduced HMOX1 (0.024 ± 0.010 vs 0.010 ± 0.004 RU, p < 0.0001), whereas in rats, high-fat diet-induced weight gain resulted in increased Hmox1 mRNA levels (0.22 ± 0.15 vs 0.54 ± 0.22 RU, p = 0.005). These changes were in parallel with changes in BMI and adipose tissue markers of iron excess, adipogenesis and inflammation. In human adipocytes, iron excess and inflammation led to increased HMOX1 mRNA levels. HMOX1 induction (by haem arginate [hemin] administration), resulted in a significant reduction of mitochondrial respiratory capacity (including basal respiration and spare respiratory capacity), glucose uptake and adipogenesis in parallel with increased expression of inflammatory- and iron excess-related genes. HMOX1 is an important marker of iron excess

  20. Oxide Dispersion Strengthened Iron Aluminide by CVD Coated Powders

    SciTech Connect

    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.

  1. Reconstruction of Extracellular Respiratory Pathways for Iron(III) Reduction in Shewanella Oneidensis Strain MR-1

    PubMed Central

    Coursolle, Dan; Gralnick, Jeffrey A.

    2012-01-01

    Shewanella oneidensis strain MR-1 is a facultative anaerobic bacterium capable of respiring a multitude of electron acceptors, many of which require the Mtr respiratory pathway. The core Mtr respiratory pathway includes a periplasmic c-type cytochrome (MtrA), an integral outer-membrane β-barrel protein (MtrB), and an outer-membrane-anchored c-type cytochrome (MtrC). Together, these components facilitate transfer of electrons from the c-type cytochrome CymA in the cytoplasmic membrane to electron acceptors at and beyond the outer-membrane. The genes encoding these core proteins have paralogs in the S. oneidensis genome (mtrB and mtrA each have four while mtrC has three) and some of the paralogs of mtrC and mtrA are able to form functional Mtr complexes. We demonstrate that of the additional three mtrB paralogs found in the S. oneidensis genome, only MtrE can replace MtrB to form a functional respiratory pathway to soluble iron(III) citrate. We also evaluate which mtrC/mtrA paralog pairs (a total of 12 combinations) are able to form functional complexes with endogenous levels of mtrB paralog expression. Finally, we reconstruct all possible functional Mtr complexes and test them in a S. oneidensis mutant strain where all paralogs have been eliminated from the genome. We find that each combination tested with the exception of MtrA/MtrE/OmcA is able to reduce iron(III) citrate at a level significantly above background. The results presented here have implications toward the evolution of anaerobic extracellular respiration in Shewanella and for future studies looking to increase the rates of substrate reduction for water treatment, bioremediation, or electricity production. PMID:22363330

  2. The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part II. The reduction of iron oxide/carbon composites

    SciTech Connect

    Sohn, I.; Fruehan, R.J.

    2006-04-15

    The reduction of iron oxide/carbon composite pellets with hydrogen at 900{sup o}C to 1000{sup o}C was studied. Compared to hydrogen, the reduction by carbon was negligible at 900 degrees C and below. However, significant carbon oxidation of the iron oxide/graphite pellets by H{sub 2O generated from the reduction of Fe{sub 2}O{sub 3} by H-2 was observed. At higher temperatures, reduction by carbon complicates the overall reduction mechanism, with the iron oxide/graphite composite pellet found to be more reactive than the iron oxide/char composite pellet. From the scanning electron micrographs, partially reduced composite pellets showed a typical topochemical interface with an intermediate region between an oxygen-rich unreacted core and an iron-rich outer shell. To determine the possibility of reduction by volatiles, a layer of iron oxide powders was spread on top of a high volatile containing bituminous coal and heated inside a reactor using infra-red radiation. By separating the individual reactions involved for an iron oxide/coal mixture where a complex set of reactions occur simultaneously, it was possible to determine the sole effect of volatile reduction. It was found that the light reducing gases evolve initially and react with the iron oxide, with complex hydrocarbons evolving at the later stages. The volatiles caused about 20 to 50% reduction of the iron oxide.

  3. The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part II. The reduction of iron oxide/carbon composites

    NASA Astrophysics Data System (ADS)

    Sohn, I.; Fruehan, R. J.

    2006-04-01

    The reduction of iron oxide/carbon composite pellets with hydrogen at 900 °C to 1000 °C was studied. Compared to hydrogen, the reduction by carbon was negligible at 900 °C and below. However, significant carbon oxidation of the iron oxide/graphite pellets by H2O generated from the reduction of Fe2O3 by H2 was observed. At higher temperatures, reduction by carbon complicates the overall reduction mechanism, with the iron oxide/graphite composite pellet found to be more reactive than the iron oxide/char composite pellet. From the scanning electron micrographs, partially reduced composite pellets showed a typical topochemical interface with an intermediate region between an oxygen-rich unreacted core and an iron-rich outer shell. To determine the possibility of reduction by volatiles, a layer of iron oxide powders was spread on top of a high volatile containing bituminous coal and heated inside a reactor using infra-red radiation. By separating the individual reactions involved for an iron oxide/coal mixture where a complex set of reactions occur simultaneously, it was possible to determine the sole effect of volatile reduction. It was found that the light reducing gases evolve initially and react with the iron oxide, with complex hydrocarbons evolving at the later stages. The volatiles caused about 20 to 50 pct reduction of the iron oxide.

  4. Nitrative and oxidative modifications of enolase are associated with iron in iron-overload rats and in vitro.

    PubMed

    Lu, Naihao; Li, Xueli; Li, Jinyang; Xu, Wenjing; Li, Hailing; Gao, Zhonghong

    2011-03-01

    Iron overload is one of the most common iron-related toxicities, and liver is the major organ that is injured. Although oxidative stress is well accepted in the pathological mechanism of iron overload, nitrative modification in liver and the role of iron are relatively unknown. In this work, the nitrative and oxidative stress in liver was investigated in an iron-overload rat model. It was found that after 15 weeks of iron dextran administration, consistent with the increase of iron content in rat liver, both protein tyrosine nitration and protein oxidation were clearly elevated. By means of immunoprecipitation analysis, it was found that enolase nitration and oxidation status were significantly increased in iron-overload liver, whereas both α-enolase expression and activity were clearly decreased. The effects of different forms of iron on NaNO(2)-H(2)O(2)- and peroxynitrite (ONOO(-))-dependent enolase nitration and oxidation were further investigated in vitro to elucidate the possible role of iron in enolase dysfunction in vivo. Compared with EDTA-Fe(III), ferric citrate, and ferritin, heme (hemin and hemoglobin) showed higher efficiency in catalyzing protein nitration in both models. Besides the major contribution of free iron (Fe(2+) and Fe(3+)) to catalyze protein oxidation, Fe(2+) also directly acted as a competitive inhibitor and produced a significant decrease in enzyme activity. These results suggest that the existence of various forms of iron is an important contributing factor to the elevated nitrative/oxidative modifications and diminished activity of α-enolase in the development and progress of iron-overload-associated syndromes.

  5. The oxidation behavior of ODS iron aluminides

    SciTech Connect

    Pint, B.A.; Tortorelli, P.F.; Wright, I.G.

    1996-05-01

    Oxide-dispersed Fe-28at.%Al-2%Cr alloys were produced by a powder metallurgy technique followed by hot extrusion. A variety of stable oxides were added to the base alloy to assess the effect of these dopants on the oxidation behavior at 1200{degrees}C in air and O{sub 2}. An Al{sub 2}O{sub 3} dispersion flattened the {alpha}-Al{sub 2}O{sub 3} scale, but produced none of the other reactive element effects and had an adverse influence on the long-term oxidation behavior. A Y{sub 2}O{sub 3} dispersion improved the alumina scale adhesion relative to a Zr alloy addition at 1200{degrees} and 1300{degrees}C. However, the Y{sub 2}O{sub 3} dispersion was not as effective in improving scale adhesion in Fe{sub 3}Al as it is in FeCrAl. This inferior performance is attributed to a larger amount of interfacial void formation on ODS Fe{sub 3}Al.

  6. Iron oxidation kinetics and autotrophic bacteria in acidified environments

    SciTech Connect

    Barry, R.C.

    1993-01-01

    Iron oxidation in the presence of lake sediment collected from an acidic alpine lake was three orders of magnitude faster than in filtered lakewater without sediment. When kinetic rates in the presence of sediment were normalized on a surface area basis, they fell within a narrow range, and the assumption of a first order dependence of rate on surface area was supported. The relative influence on heterogeneous rate of ferrous iron oxidation of the five metal oxides studied can be ranked SiO[sub 2] [approx] Al[sub 2]O[sub 3] [much lt] Fe[sub 2] O[sub 3] [approx] MnO[sub 2] [approx] TiO[sub 2], with a difference of three orders of magnitude separating the aluminum and iron oxides. The rate constants on a surface area basis were, respectively, 1.8 [times] 10[sup 10], 4.6 [times] 10[sup 10], 1.4 [times] 10[sup 13], 2.3 [times] 10[sup 13] and 5.3 [times] 10[sup 13]M[sup [minus]2] atm[sup [minus]1] sec[sup [minus]1]m[sup [minus]2]. Studies at low oxygen concentrations suggested that at low pO[sub 2] oxygenation may not be first order with respect to oxygen concentration. Biological processes were found to enhance oxidation kinetics by two orders of magnitude on a surface area basis in comparison with a gamma irradiated control. Oxidation rate in the presence of irradiated sediment was in turn approximately 130 times greater than for oxidation in deionized water. The importance of biological activity in environments exhibiting photoreduction of iron was further studied by development of a polyclonal antibody test for the detection of the iron oxidizing autotroph Thiobacillus ferrooxidans. T. ferrooxidans was found in the Snake River and its tributaries in the Colorado Rocky mountains. Tests for T. ferrooxidans in samples collected at Lake Cristallina, Canton Ticino, Switzerland and McDonalds Branch, Lebanon State Forest, New Jersey were negative.

  7. Respiratory Effects of Inhaled Single-Walled Carbon Nanotubes: The Role of Particle Morphology and Iron Content

    NASA Astrophysics Data System (ADS)

    Madl, Amy Kathleen

    centriacinus were used to assess immediate and persistent effects. The oxidant and inflammatory capacity of microdissected airways of exposed animals was used to assess the ability to withstand an additional oxidant insult. Comparing the effects observed in the acute versus subacute inhalation studies, the effects of SWCNTs appeared to follow a dose-response pattern, where the effects were further pronounced and, in some cases, more persistent under more severe or prolonged exposure conditions. In addition, results showed different timing and extent of responses resulting from exposure to SWCNTs containing varied amounts of iron. Depending on the endpoint of interest, responses of SWCNTs sometimes followed that of CB while in other circumstances matched that of crocidolite. Notably, FeSWCNTs exposed animals were unable to respond to an additional oxidant challenge and cSWCNTs exposed animals had a delayed and persistent development of mucous cells in the distal airways. In conclusion, while some toxicity endpoints follow patterns comparable to CB or crocidolite, the respiratory effects of inhaled FeSWCNTs and cSWCNTs appear to be unique. Further research is needed to evaluate whether these changes are suggestive of precursor events to pathologic changes that might develop under more severe or prolonged exposure conditions. Systematic toxicity testing and intentional physicochemical modifications will provide further insights as to the mechanisms by which SWCNTs cause these unique effects. It would be of hope that nanomaterials, such as SWCNTs, can be designed in way to maximize their societal benefits through various energy, medical, and technological applications but minimize their potential human health and environmental risks.

  8. Intratumoral Iron Oxide Nanoparticle Hyperthermia and Radiation Cancer Treatment.

    PubMed

    Hoopes, Pj; Strawbridge, Rr; Gibson, Uj; Zeng, Q; Pierce, Ze; Savellano, M; Tate, Ja; Ogden, Ja; Baker, I; Ivkov, R; Foreman, Ar

    2007-02-13

    The potential synergism and benefit of combined hyperthermia and radiation for cancer treatment is well established, but has yet to be optimized clinically. Specifically, the delivery of heat via external arrays /applicators or interstitial antennas has not demonstrated the spatial precision or specificity necessary to achieve appropriate a highly positive therapeutic ratio. Recently, antibody directed and possibly even non-antibody directed iron oxide nanoparticle hyperthermia has shown significant promise as a tumor treatment modality. Our studies are designed to determine the effects (safety and efficacy) of iron oxide nanoparticle hyperthermia and external beam radiation in a murine breast cancer model. MTG-B murine breast cancer cells (1 × 10(6)) were implanted subcutaneous in 7 week-old female C3H/HeJ mice and grown to a treatment size of 150 mm(3) +/- 50 mm(3). Tumors were then injected locally with iron oxide nanoparticles and heated via an alternating magnetic field (AMF) generator operated at approximately 160 kHz and 400 - 550 Oe. Tumor growth was monitored daily using standard 3-D caliper measurement technique and formula. specific Mouse tumors were heated using a cooled, 36 mm diameter square copper tube induction coil which provided optimal heating in a 1 cm wide region in the center of the coil. Double dextran coated 80 nm iron oxide nanoparticles (Triton Biosystems) were used in all studies. Intra-tumor, peri-tumor and rectal (core body) temperatures were continually measured throughout the treatment period. Preliminary in vivo nanoparticle-AMF hyperthermia (167 KHz and 400 or 550 Oe) studies demonstrated dose responsive cytotoxicity which enhanced the effects of external beam radiation. AMF associated eddy currents resulted in nonspecific temperature increases in exposed tissues which did not contain nanoparticles, however these effects were minor and not injurious to the mice. These studies also suggest that iron oxide nanoparticle hyperthermia

  9. Intratumoral iron oxide nanoparticle hyperthermia and radiation cancer treatment

    NASA Astrophysics Data System (ADS)

    Hoopes, P. J.; Strawbridge, R. R.; Gibson, U. J.; Zeng, Q.; Pierce, Z. E.; Savellano, M.; Tate, J. A.; Ogden, J. A.; Baker, I.; Ivkov, R.; Foreman, A. R.

    2007-02-01

    The potential synergism and benefit of combined hyperthermia and radiation for cancer treatment is well established, but has yet to be optimized clinically. Specifically, the delivery of heat via external arrays /applicators or interstitial antennas has not demonstrated the spatial precision or specificity necessary to achieve appropriate a highly positive therapeutic ratio. Recently, antibody directed and possibly even non-antibody directed iron oxide nanoparticle hyperthermia has shown significant promise as a tumor treatment modality. Our studies are designed to determine the effects (safety and efficacy) of iron oxide nanoparticle hyperthermia and external beam radiation in a murine breast cancer model. Methods: MTG-B murine breast cancer cells (1 x 106) were implanted subcutaneous in 7 week-old female C3H/HeJ mice and grown to a treatment size of 150 mm3 +/- 50 mm3. Tumors were then injected locally with iron oxide nanoparticles and heated via an alternating magnetic field (AMF) generator operated at approximately 160 kHz and 400 - 550 Oe. Tumor growth was monitored daily using standard 3-D caliper measurement technique and formula. specific Mouse tumors were heated using a cooled, 36 mm diameter square copper tube induction coil which provided optimal heating in a 1 cm wide region in the center of the coil. Double dextran coated 80 nm iron oxide nanoparticles (Triton Biosystems) were used in all studies. Intra-tumor, peri-tumor and rectal (core body) temperatures were continually measured throughout the treatment period. Results: Preliminary in vivo nanoparticle-AMF hyperthermia (167 KHz and 400 or 550 Oe) studies demonstrated dose responsive cytotoxicity which enhanced the effects of external beam radiation. AMF associated eddy currents resulted in nonspecific temperature increases in exposed tissues which did not contain nanoparticles, however these effects were minor and not injurious to the mice. These studies also suggest that iron oxide nanoparticle

  10. Biogenic nanosized iron oxides obtained from cultivation of iron bacteria from the genus Leptothrix.

    PubMed

    Nedkov, I; Slavov, L; Angelova, R; Blagoev, B; Kovacheva, D; Abrashev, M V; Iliev, M; Groudeva, V

    2016-10-01

    A detailed investigation of nanostructured iron oxides/(oxy)hydroxides gathered after cultivation of bacteria from the genus Leptothrix as iron (II) oxidizers is presented. A specific type of medium is selected for the cultivation of the bacteria. Results for sediment powder and bio-film on glass substrate samples from the same media are discussed. XRD, Raman spectroscopy, SEM, and TEM images and PPMS measurements are used to prove the exact composition of the biogenic products and to interpret the oxidation process. Analysis of the data collected shows that around 80 % of the iron (II) from the growth medium has been transformed into iron (III) in the form of different (oxy)hydroxides, with the rest found to be in a mixed 2,5 valence in magnetite. Our investigation shows that the bio-film sample has a phase content different from that of the powdered biomass and that lepidocrocite (γ-FeOOH) is the predominant and the initial biogenic phase in both samples. Magnetite nanoparticles are a secondary product in the bio-film, part of which possesses a defective quasi-maghemite surface layer. In the powdered biomass, the oxidation steps are not fully completed. The initial products are non-stoichiometric and due to the mixed ferric and ferrous ions present, they develop into: (i) lepidocrocite (γ-FeOOH) as a basic sediment, (ii) magnetite (Fe3O4) and (iii) goethite (α-FeOOH) in small quantities. The average size of all iron-bearing particles is found to be below 30 nm. The magnetic measurements performed show a superparamagnetic behavior of the material at room temperature.

  11. Synthesis of iron oxide/manganese oxide composite particles and their magnetic properties

    NASA Astrophysics Data System (ADS)

    Ullrich, Aladin; Hohenberger, Stefan; Özden, Ayberk; Horn, Siegfried

    2014-08-01

    We have investigated the synthesis and structural as well as magnetic properties of composite nanoparticles, including core-shell particles, consisting of iron and manganese oxides. The synthesis is based on thermal decomposition of suitable metal oleates in a high boiling solvent. Seed particles are used to avoid homogeneous nucleation and to initiate the formation of heterogeneous systems. The as-synthesized particles were characterized by energy filtered transmission electron microscopy (EFTEM) and SQUID magnetometry. The synthesized nanoparticles had diameters between 10 and 20 nm and consisted of manganese oxide and iron oxide.

  12. Oxidative effect of several intravenous iron complexes in the rat.

    PubMed

    Bailie, George R; Schuler, Catherine; Leggett, Robert E; Li, Hsin; Li, Hsin-Dat; Patadia, Hiten; Levin, Robert

    2013-06-01

    The objective of this study was to compare the oxidative stress induced in rat internal organs by the administration of the following clinically used intravenous (IV) iron (Fe) containing compounds: iron sucrose (IS), iron dextran (ID), ferric carboxymaltose and ferumoxytol. Groups of six adult rats received 1 mg/kg of each compound weekly for 5 doses. Seven days following the last dose, animals were euthanized and tissue samples of heart, lung, liver, and kidney were obtained, washed in warmed saline and frozen under liquid nitrogen and stored at -80 °C for analysis for nitrotyrosine (NT) and dinitro phenyl (DNP) as markers of oxidative stress. All tissues showed a similar pattern of oxidative stress. All Fe products stimulated an increase in the tissue concentration of both NT and DNP. In general, DNP was stimulated significantly less than NT except for IS. DNP was stimulated to an equal degree except for ID where NT was significantly higher than the NT concentrations in all other Fe compounds. ID produced over 10-fold the concentration of NT than any other Fe. IV Fe compounds present a risk of oxidative stress to a variety of internal organs. However, we found that IS was the least damaging and ID was the worst.

  13. Iron oxide nanotubes synthesized via template-based electrodeposition.

    PubMed

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

    2014-05-21

    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.

  14. Niobian iron oxides as heterogeneous Fenton catalysts for environmental remediation

    NASA Astrophysics Data System (ADS)

    Oliveira, Diana Q. L.; Oliveira, Luiz C. A.; Murad, Enver; Fabris, José D.; Silva, Adilson C.; de Menezes, Lucas Morais

    2010-01-01

    Heterogeneous Fenton or Fenton-like reagents consist of a mixture of an iron-containing solid matrix and a liquid medium with H2O2. The Fenton system is based on the reaction between Fe2 + and H2O2 to produce highly reactive intermediate hydroxyl radicals ( • OH), which are able to oxidize organic contaminants, whereas the Fenton-like reaction is based on the reaction between Fe3 + and H2O2. These heterogeneous systems offer several advantages over their homogeneous counterparts, such as no sludge formation, operation at near-neutral pH and the possibility of recycling the iron promoter. Some doping transition cations in the iron oxide structure are believed to enhance the catalytic efficiency for the oxidation of organic substrates in water. In this work, goethites synthesized in presence of niobium served as precursors for the preparation of magnetites (niobian magnetites) via chemical reduction with hydrogen at 400°C. These materials were used as Fenton-like catalysts. Both groups of (Nb, Fe)-oxide samples were characterized by 57Fe Mössbauer spectroscopy at 298 K. The results show that increasing niobium contents raise the catalytic potential for decomposition of methylene blue, which was, in this work, used as a model molecule for organic substrates in water.

  15. Synthesis and properties of magnetic iron oxide/platinum nanocomposites

    NASA Astrophysics Data System (ADS)

    Serga, V.; Maiorov, M.; Kulikova, L.; Krumina, A.; Karashanova, D.

    2015-03-01

    Iron oxide/platinum nanocomposites have been synthesized by the extractive-pyrolytic method (EPM) involving gradual decomposition of iron capronate and n-trioctylammonium hexachloroplatinate initially produced by solvent extraction. The content of platinum in the composites was 1.2 wt%, 2.4 wt% and 4.8 wt%. Phase composition, morphology and magnetic properties of the produced materials were investigated. XRD analysis and magnetic measurements show that the magnetic phase (magnetite Fe3O4) dominates in a carrier sample produced by the pyrolysis of iron carboxylate, but hematite α-Fe2O3 exists there as an admixture. Referring to the TEM results, the produced composites contain ultra-disperse platinum particles on the carrier, and the mean size of these varies from 3 nm to 9 nm.

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

    PubMed

    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.

  17. Curcumin Attenuates Iron Accumulation and Oxidative Stress in the Liver and Spleen of Chronic Iron-Overloaded Rats

    PubMed Central

    Badria, Farid A.; Ibrahim, Ahmed S.; Badria, Adel F.; Elmarakby, Ahmed A.

    2015-01-01

    Objectives Iron overload is now recognized as a health problem in industrialized countries, as excessive iron is highly toxic for liver and spleen. The potential use of curcumin as an iron chelator has not been clearly identified experimentally in iron overload condition. Here, we evaluate the efficacy of curcumin to alleviate iron overload-induced hepatic and splenic abnormalities and to gain insight into the underlying mechanisms. Design and Methods Three groups of male adult rats were treated as follows: control rats, rats treated with iron in a drinking water for 2 months followed by either vehicle or curcumin treatment for 2 more months. Thereafter, we studied the effects of curcumin on iron overload-induced lipid peroxidation and anti-oxidant depletion. Results Treatment of iron-overloaded rats with curcumin resulted in marked decreases in iron accumulation within liver and spleen. Iron-overloaded rats had significant increases in malonyldialdehyde (MDA), a marker of lipid peroxidation and nitric oxide (NO) in liver and spleen when compared to control group. The effects of iron overload on lipid peroxidation and NO levels were significantly reduced by the intervention treatment with curcumin (P<0.05). Furthermore, the endogenous anti-oxidant activities/levels in liver and spleen were also significantly decreased in chronic iron overload and administration of curcumin restored the decrease in the hepatic and splenic antioxidant activities/levels. Conclusion Our study suggests that curcumin may represent a new horizon in managing iron overload-induced toxicity as well as in pathological diseases characterized by hepatic iron accumulation such as thalassemia, sickle cell anemia, and myelodysplastic syndromes possibly via iron chelation, reduced oxidative stress derived lipid peroxidation and improving the body endogenous antioxidant defense mechanism. PMID:26230491

  18. Low Temperature CO oxidation over Iron Oxide Nanoparticles Decorating Internal Structures of a Mesoporous Alumina

    NASA Astrophysics Data System (ADS)

    Kim, Il Hee; Seo, Hyun Ook; Park, Eun Ji; Han, Sang Wook; Kim, Young Dok

    2017-01-01

    Using a chemical vapor deposition method with regulated sample temperatures under ambient pressure conditions, we were able to fully decorate the internal structure of a mesoporous Al2O3 bead (~1 mm in particle diameter) with iron oxide nanoparticles (with a mean lateral size of less than 1 nm). The iron oxide-decorated Al2O3 showed a high CO oxidation reactivity, even at room temperature. Very little deactivation of the CO oxidation activity was observed with increasing reaction time at ~100 °C. Additionally, this catalyst showed high CO oxidation activity, even after annealing at ~900 °C under atmospheric conditions (i.e., the structure of the catalysts could be maintained under very harsh treatment conditions). We show that our catalysts have potential for application as oxidation catalysts in industrial processes due to the simplicity of their fabrication process as well as the high and stable catalytic performance.

  19. Low Temperature CO oxidation over Iron Oxide Nanoparticles Decorating Internal Structures of a Mesoporous Alumina

    PubMed Central

    Kim, Il Hee; Seo, Hyun Ook; Park, Eun Ji; Han, Sang Wook; Kim, Young Dok

    2017-01-01

    Using a chemical vapor deposition method with regulated sample temperatures under ambient pressure conditions, we were able to fully decorate the internal structure of a mesoporous Al2O3 bead (~1 mm in particle diameter) with iron oxide nanoparticles (with a mean lateral size of less than 1 nm). The iron oxide-decorated Al2O3 showed a high CO oxidation reactivity, even at room temperature. Very little deactivation of the CO oxidation activity was observed with increasing reaction time at ~100 °C. Additionally, this catalyst showed high CO oxidation activity, even after annealing at ~900 °C under atmospheric conditions (i.e., the structure of the catalysts could be maintained under very harsh treatment conditions). We show that our catalysts have potential for application as oxidation catalysts in industrial processes due to the simplicity of their fabrication process as well as the high and stable catalytic performance. PMID:28091561

  20. Promotion of Iron Oxide Reduction and Extracellular Electron Transfer in Shewanella oneidensis by DMSO

    PubMed Central

    Cheng, Yuan-Yuan; Li, Bing-Bing; Li, Dao-Bo; Chen, Jie-Jie; Li, Wen-Wei; Tong, Zhong-Hua; Wu, Chao; Yu, Han-Qing

    2013-01-01

    The dissimilatory metal reducing bacterium Shewanella oneidensis MR-1, known for its capacity of reducing iron and manganese oxides, has great environmental impacts. The iron oxides reducing process is affected by the coexistence of alternative electron acceptors in the environment, while investigation into it is limited so far. In this work, the impact of dimethyl sulphoxide (DMSO), a ubiquitous chemical in marine environment, on the reduction of hydrous ferric oxide (HFO) by S. oneidensis MR-1 was investigated. Results show that DMSO promoted HFO reduction by both wild type and ΔdmsE, but had no effect on the HFO reduction by ΔdmsB, indicating that such a promotion was dependent on the DMSO respiration. With the DMSO dosing, the levels of extracellular flavins and omcA expression were significantly increased in WT and further increased in ΔdmsE. Bioelectrochemical analysis show that DMSO also promoted the extracellular electron transfer of WT and ΔdmsE. These results demonstrate that DMSO could stimulate the HFO reduction through metabolic and genetic regulation in S. oneidensis MR-1, rather than compete for electrons with HFO. This may provide a potential respiratory pathway to enhance the microbial electron flows for environmental and engineering applications. PMID:24244312

  1. [Mechanisms of the effect of oxidants on the respiratory system].

    PubMed

    Strapkova, A; Nosalova, G; Franova, S; Adamicova, K

    1999-01-01

    It is known that oxidants may evoke changes of respiratory tract functions. The precise mechanisms of these changes are yet unknown. In this study possible participation of eicosanoids, cytochrome P-450 and reactive oxygen species in the changes of airways reactivity evoked by toluene exposure as the source of free radicals was followed up by an indirect method. Used drugs--naproxen (50 mg/kg b.w.), cimetidine (50 mg/kg b.w.) and N-acetylcysteine (300 mg/kg b.w.) were administered in two doses (first 30 minutes before exposure to toluene, second six hours after first dose). After exposure to toluene (2 hours in each of 3 consecutive days) was followed up reactivity of tracheal and lung smooth muscle to histamine in "in vitro" conditions. The studied substances were not administered in the control group of animals. In pretreated animals exposed to toluene the administration of naproxen, cimetidine and N-acetylcysteine does not provoke pronounced changes of tracheal smooth muscle reactivity compared to control group. More pronounced effect of these drugs with decrease contraction amplitude was detected on lung smooth muscle reactivity. According to our results it is not possible to determine the precise mechanisms which participate in changes of airways reactivity. There are probably multifactorial in nature.

  2. Iron oxide and iron carbide particles produced by the polyol method

    NASA Astrophysics Data System (ADS)

    Yamada, Y.; Shimizu, R.; Kobayashi, Y.

    2016-12-01

    Iron oxide ( γ-Fe2O3) and iron carbide (Fe3C) particles were produced by the polyol method. Ferrocene, which was employed as an iron source, was decomposed in a mixture of 1,2-hexadecandiol, oleylamine, and 1-octadecene. Particles were characterized using Mössbauer spectroscopy, X-ray diffraction, and transmission electron microscopy. It was found that oleylamine acted as a capping reagent, leading to uniform-sized (12-16 nm) particles consisting of γ-Fe 2O3. On the other hand, 1-octadecene acted as a non-coordinating solvent and a carbon source, which led to particles consisting of Fe3C and α-Fe with various sizes.

  3. Iron oxide particles as a catalyst in chemical oxidation of organic contaminants

    SciTech Connect

    Gurol, M.D.; Lin, S.S.; Bhat, N.

    1995-12-31

    This research addresses the use of ozone and hydrogen peroxide in the presence of iron oxide particles which provide a catalytic surface for conversion to hydroxyl free radical. N-butylchloride (BuCl) and monochlorobenzene (MCB) were oxidized using goethite as the catalyst. The effect of varying the dosage of hydrogen peroxide or ozone, the mass and the size of the geothite particles, the mixing speed, and the gas flow rate for ozonation was investigated. The effect of water quality in terms of pH, carbonate alkalinity and initial organic concentration on reaction rates was addressed as well. Experimental observations showed that varying the stirring speed in the reactor or the size of the iron oxide particles did not have any significant effect on the oxidation rates, indicating that the rate was controlled by the intrinsic reaction rates on iron oxide surfaces. The presence of hydrogen peroxide significantly increased the removal of BuCl, and higher dosages caused considerably higher removal. Results also demonstrated a strong dependence of BuCl removal on the iron oxide dosage. MCB adsorbed strongly on goethite, but was oxidized effectively by ozone. Hydrogen peroxide decomposed rapidly in the presence of goethite at a rate directly proportional to the rate of BuCl oxidation. These results indicate that the interaction of hydrogen peroxide with goethite particles leads to the formation of hydroxyl free radical, which is responsible for oxidation of BuCl. Similarly, ozone decomposed in the presence of goethite. The oxidation efficiency for hydrogen peroxide/goethite remained unaffected when the pH and the alkalinity were varied. Furthermore, the ozone/goethite system provided mineralization as measured by the removal of the total organic carbon. Hence, both of these oxidation processes promise to be effective in oxidation of organic compounds, and may not suffer from the limitations of other radical processes.

  4. Copper Iron Conversion Coating for Solid Oxide Fuel Cell Interconnects

    NASA Astrophysics Data System (ADS)

    Grolig, Jan Gustav; Alnegren, Patrik; Froitzheim, Jan; Svensson, Jan-Erik

    2015-11-01

    A conversion coating of iron and copper was investigated with the purpose of increasing the performance of Sanergy HT as a potential SOFC interconnect material. Samples were exposed to a simulated cathode atmosphere (air, 3 % H2O) for durations of up to 1000 h at 850 °C. Their performance in terms of corrosion, chromium evaporation and electrical resistance (ASR) was monitored and compared to uncoated and cobalt-coated Sanergy HT samples. The copper iron coating had no negative effects on corrosion protection and decreased chromium evaporation by about 80%. An Area Specific Resistance (ASR) of 10 mΩcm2 was reached after 1000 h of exposure. Scanning Electron Microscopy revealed well adherent oxide layers comprised of an inner chromia layer and an outer spinel oxide layer.

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

    PubMed

    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.

  6. Dendronized iron oxide colloids for imaging the sentinel lymph node

    NASA Astrophysics Data System (ADS)

    Jouhannaud, J.; Garofalo, A.; Felder-Flesch, D.; Pourroy, G.

    2015-03-01

    Various methods have been used in medicine for more than one century to explore the lymphatic system. Radioactive colloids (RuS labelled with 99mTc) or/and Vital Blue dye are injected around the primary tumour and detected by means of nuclear probe or visual colour inspection respectively. The simultaneous clinical use of both markers (dye and radionuclide) improves the sensitivity of detection close to 100%. Superparamagnetic iron oxides (SPIOs) are currently receiving much attention as strong T2 weighted magnetic resonance imaging contrast agents that can be potentially used for preoperative localization of sentinel nodes, but also for peroperative detection of sentinel node using hand-held probes. In that context, we present the elaboration of dendronized iron oxide nanoparticles elaborated at the Institute of Physics and Chemistry of Materials of Strasbourg.

  7. Porous Iron oxide nanorods and their photothermal applications

    NASA Astrophysics Data System (ADS)

    Larsen, George; Huang, Weijie; Zhao, Yiping; Hunyadi Murph, Simona E.

    2016-09-01

    Iron oxide is a unique semiconductor material, either as a single nanoparticle, or as a component of multifunctional nanoparticles. Its desirable properties, abundance, non-toxicity, and excellent magnetic properties make it a valuable for many applications. Porous iron oxide nanorods are able to transduce light into heat through the photothermal effect. Photothermal heating arises from the energy dissipated during light absorption leading to rapid temperature rise in close proximity to the surface of the nanoparticle. The heating effect can be efficiently harnessed to drive/promote different physical phenomena. In this report, we describe the synthesis and properties of porous Fe3O4 for photothermal applications. We then demonstrate their use as photothermally enhanced and recyclable materials for environmental remediation through sorption processes.

  8. Linear-chain assemblies of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Dhak, Prasanta; Kim, Min-Kwan; Lee, Jae Hyeok; Kim, Miyoung; Kim, Sang-Koog

    2017-07-01

    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.

  9. Iron aluminide alloy container for solid oxide fuel cells

    DOEpatents

    Judkins, Roddie Reagan; Singh, Prabhakar; Sikka, Vinod Kumar

    2000-01-01

    A container for fuel cells is made from an iron aluminide alloy. The container alloy preferably includes from about 13 to about 22 weight percent Al, from about 2 to about 8 weight percent Cr, from about 0.1 to about 4 weight percent M selected from Zr and Hf, from about 0.005 to about 0.5 weight percent B or from about 0.001 to about 1 weight percent C, and the balance Fe and incidental impurities. The iron aluminide container alloy is extremely resistant to corrosion and metal loss when exposed to dual reducing and oxidizing atmospheres at elevated temperatures. The alloy is particularly useful for containment vessels for solid oxide fuel cells, as a replacement for stainless steel alloys which are currently used.

  10. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems

    SciTech Connect

    Phan, Manh-Huong; Alonso, Javier; Khurshid, Hafsa; Lampen-Kelley, Paula; Chandra, Sayan; Stojak Repa, Kristen; Nemati, Zohreh; Das, Raja; Iglesias, Óscar; Srikanth, Hariharan

    2016-11-23

    The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for prospective applications in nanospintronics and nanomedicine. However, the physical origin of EB is not fully understood. Recent advances in chemical synthesis provide a unique opportunity to explore EB in a variety of iron oxide-based nanostructures ranging from core/shell to hollow and hybrid composite nanoparticles. Experimental and atomistic Monte Carlo studies have shed light on the roles of interface and surface spins in these nanosystems. This review paper aims to provide a thorough understanding of the EB and related phenomena in iron oxide-based nanoparticle systems, knowledge of which is essential to tune the anisotropic magnetic properties of exchange-coupled nanoparticle systems for potential applications.

  11. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems

    DOE PAGES

    Phan, Manh-Huong; Alonso, Javier; Khurshid, Hafsa; ...

    2016-11-23

    The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for prospective applications in nanospintronics and nanomedicine. However, the physical origin of EB is not fully understood. Recent advances in chemical synthesis provide a unique opportunity to explore EB in a variety of iron oxide-based nanostructures ranging from core/shell to hollow and hybrid composite nanoparticles. Experimental and atomistic Monte Carlo studies have shed light on the roles of interface and surface spins in these nanosystems. This review paper aims to provide a thorough understanding of the EB and relatedmore » phenomena in iron oxide-based nanoparticle systems, knowledge of which is essential to tune the anisotropic magnetic properties of exchange-coupled nanoparticle systems for potential applications.« less

  12. Reflection spectra and magnetochemistry of iron oxides and natural surfaces

    NASA Technical Reports Server (NTRS)

    Wasilewski, P.

    1978-01-01

    The magnetic properties and spectral characteristics of iron oxides are distinctive. Diagnostic features in reflectance spectra (0.5 to 2.4 micron) for alpha Fe2O3, gamma Fe2O3, and FeOOH include location of Fe3(+) absorption features, intensity ratios at various wavelengths, and the curve shape between 1.2 micron and 2.4 micron. The reflection spectrum of natural rock surfaces are seldom those of the bulk rock because of weathering effects. Coatings are found to be dominated by iron oxides and clay. A simple macroscopic model of rock spectra (based on concepts of stains and coatings) is considered adequate for interpretation of LANDSAT data. The magnetic properties of materials associated with specific spectral types and systematic changes in both spectra and magnetic properties are considered.

  13. Potential toxicity of superparamagnetic iron oxide nanoparticles (SPION)

    PubMed Central

    Singh, Neenu; Jenkins, Gareth J.S.; Asadi, Romisa; Doak, Shareen H.

    2010-01-01

    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. PMID:22110864

  14. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems

    PubMed Central

    Phan, Manh-Huong; Alonso, Javier; Khurshid, Hafsa; Lampen-Kelley, Paula; Chandra, Sayan; Stojak Repa, Kristen; Nemati, Zohreh; Das, Raja; Iglesias, Óscar; Srikanth, Hariharan

    2016-01-01

    The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for prospective applications in nanospintronics and nanomedicine. However, the physical origin of EB is not fully understood. Recent advances in chemical synthesis provide a unique opportunity to explore EB in a variety of iron oxide-based nanostructures ranging from core/shell to hollow and hybrid composite nanoparticles. Experimental and atomistic Monte Carlo studies have shed light on the roles of interface and surface spins in these nanosystems. This review paper aims to provide a thorough understanding of the EB and related phenomena in iron oxide-based nanoparticle systems, knowledge of which is essential to tune the anisotropic magnetic properties of exchange-coupled nanoparticle systems for potential applications. PMID:28335349

  15. Nanovectors for anticancer agents based on superparamagnetic iron oxide nanoparticles

    PubMed Central

    Douziech-Eyrolles, Laurence; Marchais, Hervé; Hervé, Katel; Munnier, Emilie; Soucé, Martin; Linassier, Claude; Dubois, Pierre; Chourpa, Igor

    2007-01-01

    During the last decade, the application of nanotechnologies for anticancer drug delivery has been extensively explored, hoping to improve the efficacy and to reduce side effects of chemotherapy. The present review is dedicated to a certain kind of anticancer drug nanovectors developed to target tumors with the help of an external magnetic field. More particularly, this work treats anticancer drug nanoformulations based on superparamagnetic iron oxide nanoparticles coated with biocompatible polymers. The major purpose is to focus on the specific requirements and technological difficulties related to controlled delivery of antitumoral agents. We attempt to state the problem and its possible perspectives by considering the three major constituents of the magnetic therapeutic vectors: iron oxide nanoparticles, polymeric coating and anticancer drug. PMID:18203422

  16. Superparamagnetic iron oxide nanoparticle uptake alters M2 macrophage phenotype, iron metabolism, migration and invasion.

    PubMed

    Rojas, José M; Sanz-Ortega, Laura; Mulens-Arias, Vladimir; Gutiérrez, Lucía; Pérez-Yagüe, Sonia; Barber, Domingo F

    2016-05-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have shown promise as contrast agents and nanocarriers for drug delivery. Their impact on M2-polarised macrophages has nonetheless not been well studied. Here we explored the effects of SPIONs coated with dimercaptosuccinic acid, aminopropyl silane or aminodextran in two M2 macrophage models (murine primary IL-4-activated bone marrow-derived macrophages and human M2-like differentiated THP-1 cells). All SPIONs were internalised and no cell toxicity was observed. SPION treatment produced reactive oxygen species and activated the extracellular signal-regulated kinase and AKT pathways. After 24-h SPION incubation, M2 macrophages switched their iron metabolism towards an iron-replete state. SPION treatment in both M2 macrophage models altered their M2 activation profiles, promoted IL-10 production, and stimulated protease-dependent invasion. These results highlight the need to evaluate the interactions between SPIONs and cells to take full advantage of the intrinsic properties of these nanoparticles in biological systems. Superparamagnetic iron oxide nanoparticles (SPIONs) have been used as an MRI contrast agent in many experimental studies. The authors here investigated the effects of these nanoparticles on M2 macrophages after cellular uptake. The findings of cell activation further enhanced our current knowledge on the interaction of SPIONS with macrophages. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Reducing arsenic accumulation in rice grain through iron oxide amendment.

    PubMed

    Farrow, Eric M; Wang, Jianmin; Burken, Joel G; Shi, Honglan; Yan, Wengui; Yang, John; Hua, Bin; Deng, Baolin

    2015-08-01

    Effects of soil-arsenic (As), phosphorus and iron oxide on As accumulation in rice grain were investigated. Cultivars that have significantly different sensitivity to As, straighthead-resistant Zhe 733 and straighthead-susceptible Cocodrie, were used to represent different cultivar varieties. The grain accumulation of other elements of concern, selenium (Se), molybdenum (Mo), and cadmium (Cd) was also monitored. Results demonstrated that high soil-As not only resulted in high grain-As, but could also result in high grain-Se, and Zhe 733 had significantly less grain-As than Cocodrie did. However, soil-As did not impact grain-Mo and Cd. Among all elements monitored, iron oxide amendment significantly reduced grain-As for both cultivars, while the phosphate application only reduced grain-Se for Zhe 733. Results also indicated that cultivar type significantly impacted grain accumulation of all monitored trace elements. Therefore, applying iron oxide to As-contaminated land, in addition to choosing appropriate rice cultivar, can effectively reduce the grain accumulation of As.

  18. Gentamicin coated iron oxide nanoparticles as novel antibacterial agents

    NASA Astrophysics Data System (ADS)

    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.

  19. Modulated self-reversed magnetic hysteresis in iron oxides

    NASA Astrophysics Data System (ADS)

    Ma, Ji; Chen, Kezheng

    2017-02-01

    The steadfast rule of a ferromagnetic hysteresis loop claims its saturation positioned within the first and third quadrants, whereas its saturation positioned in the second and fourth quadrants (named as self-reversed magnetic hysteresis) is usually taken as an experimental artifact and is always intentionally ignored. In this report, a new insight in this unique hysteresis phenomenon and its modulation were discussed in depth. Different iron oxides (magnetite, maghemite and hematite) with varying dimensions were soaked in FeCl3 aqueous solution and absorbed Fe3+ cations due to their negative enough surface zeta potentials. These iron oxides@Fe3+ core-shell products exhibit well pronounced self-reversed magnetic hysteresis which concurrently have typical diamagnetic characteristics and essential ferromagnetic features. The presence of pre-magnetized Fe3+ shell and its negatively magnetic exchange coupling with post-magnetized iron-oxide core is the root cause for the observed phenomena. More strikingly, this self-reversed magnetic hysteresis can be readily modulated by changing the core size or by simply controlling Fe3+ concentration in aqueous solution. It is anticipated that this work will shed new light on the development of spintronics, magnetic recording and other magnetically-relevant fields.

  20. Modulated self-reversed magnetic hysteresis in iron oxides

    PubMed Central

    Ma, Ji; Chen, Kezheng

    2017-01-01

    The steadfast rule of a ferromagnetic hysteresis loop claims its saturation positioned within the first and third quadrants, whereas its saturation positioned in the second and fourth quadrants (named as self-reversed magnetic hysteresis) is usually taken as an experimental artifact and is always intentionally ignored. In this report, a new insight in this unique hysteresis phenomenon and its modulation were discussed in depth. Different iron oxides (magnetite, maghemite and hematite) with varying dimensions were soaked in FeCl3 aqueous solution and absorbed Fe3+ cations due to their negative enough surface zeta potentials. These iron oxides@Fe3+ core-shell products exhibit well pronounced self-reversed magnetic hysteresis which concurrently have typical diamagnetic characteristics and essential ferromagnetic features. The presence of pre-magnetized Fe3+ shell and its negatively magnetic exchange coupling with post-magnetized iron-oxide core is the root cause for the observed phenomena. More strikingly, this self-reversed magnetic hysteresis can be readily modulated by changing the core size or by simply controlling Fe3+ concentration in aqueous solution. It is anticipated that this work will shed new light on the development of spintronics, magnetic recording and other magnetically-relevant fields. PMID:28220793

  1. Modulated self-reversed magnetic hysteresis in iron oxides.

    PubMed

    Ma, Ji; Chen, Kezheng

    2017-02-21

    The steadfast rule of a ferromagnetic hysteresis loop claims its saturation positioned within the first and third quadrants, whereas its saturation positioned in the second and fourth quadrants (named as self-reversed magnetic hysteresis) is usually taken as an experimental artifact and is always intentionally ignored. In this report, a new insight in this unique hysteresis phenomenon and its modulation were discussed in depth. Different iron oxides (magnetite, maghemite and hematite) with varying dimensions were soaked in FeCl3 aqueous solution and absorbed Fe(3+) cations due to their negative enough surface zeta potentials. These iron oxides@Fe(3+) core-shell products exhibit well pronounced self-reversed magnetic hysteresis which concurrently have typical diamagnetic characteristics and essential ferromagnetic features. The presence of pre-magnetized Fe(3+) shell and its negatively magnetic exchange coupling with post-magnetized iron-oxide core is the root cause for the observed phenomena. More strikingly, this self-reversed magnetic hysteresis can be readily modulated by changing the core size or by simply controlling Fe(3+) concentration in aqueous solution. It is anticipated that this work will shed new light on the development of spintronics, magnetic recording and other magnetically-relevant fields.

  2. Magnetic Signatures of Several Synthetic Iron Oxides Alteration Pathways

    NASA Astrophysics Data System (ADS)

    Guyodo, Y.; Ona-Nguema, G.; Bonville, P.; Lagroix, F.

    2009-05-01

    The alteration of naturally occurring iron oxides and oxyhydroxides, under the influence of varying environmental conditions, including micro-environments and biological activity, is an important research topic because their connection to past climate variations remains to be elucidated. One approach to this subject matter is to perform laboratory experiments using synthetic iron oxides (sensus lato) subjected to specific physical and bio-chemical conditions. In our presentation, we will report on alteration experiments performed on synthetic lepidocrocite (γ-FeOOH) and maghemite (γ-Fe2O3) particles. A first approach consists in using the starting materials as electron acceptors in bio-reduction experiments involving the iron- reducing bacteria Shewanella putrefaciens and leading to the formation of magnetite (Fe3O4) particles. In a parallel approach, the starting materials are converted to magnetite by slow heating in CO/CO2 atmosphere. Further alteration can be done by slow heating in air, this time inducing aging and oxidation of the material. At various stages of our experiments, the samples are characterized using both magnetic (low-temperature, low-field and high-field magnetic measurements, Mossbaüer spectroscopy, etc.) and non-magnetic techniques (XRD, HRTEM, etc.). The various experiments conducted on these samples will allow us to study different pathways of magnetite formation and alteration in the environment, including solid-state conversion, partial or total dissolution/precipitation, and particles aggregation.

  3. Iron oxide magnetic nanoparticles synthesized by atmospheric microplasmas

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Kaur, Parvin; Tan, Augustine Tuck Lee; Singh, Rajveer; Lee, Paul Choon Keat; Springham, Stuart Victor; Ramanujan, Raju V.; Rawat, R. S.

    2014-08-01

    This paper presents the synthesis of iron oxide nanoparticles using the atmospheric microplasma (AMP). The properties of iron oxide nanoparticles synthesized using AMP are compared with particles (i) formed in as-prepared solution and (ii) prepared using thermal decomposition method. Iron oxide nanoparticles prepared by all the 3 treatment methods exhibit quite soft ferromagnetic properties with coercivities less than 10 G. The AMP synthesis technique was found to be more efficient and better than thermal decomposition method due to ultra-shorter experiment time (around 2.5 min) as compared to 90 min required for thermal decomposition method. Moreover, AMP synthesized nanoparticles are better isolated and of smaller size than thermal decomposition ones. The effect of plasma discharge timings on synthesized nanoparticles has also been studied in this work. Coercivity of synthesized nanoparticles decreases with the increasing plasma discharge timings from 3 to 10 min. The nanoparticles synthesized using plasma discharge timing of 10 min exhibit the smallest coercivity of around 3 G. This suggests a high possibility of achieving super-paramagnetic nanoparticles by optimizing the plasma discharge timings of AMP.

  4. Iron Deficiency Anemia in Relation to Respiratory Disease and Social Behaviors In Low-Income Infants in France.

    ERIC Educational Resources Information Center

    Honig, Alice Sterling

    1993-01-01

    Examined a sample of 177 infants (age 9 through 12 months) with iron deficiency anemia (IDA) from low-income French, African, and North African Muslim families in Paris. Found a higher than normal incidence of otitis media and respiratory diseases such as bronchitis among the infants. Also examined the relationship between infant IDA and child…

  5. Iron Deficiency Anemia in Relation to Respiratory Disease and Social Behaviors In Low-Income Infants in France.

    ERIC Educational Resources Information Center

    Honig, Alice Sterling

    1993-01-01

    Examined a sample of 177 infants (age 9 through 12 months) with iron deficiency anemia (IDA) from low-income French, African, and North African Muslim families in Paris. Found a higher than normal incidence of otitis media and respiratory diseases such as bronchitis among the infants. Also examined the relationship between infant IDA and child…

  6. Electron uptake by iron-oxidizing phototrophic bacteria

    SciTech Connect

    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. Electron uptake by iron-oxidizing phototrophic bacteria.

    PubMed

    Bose, A; Gardel, E J; Vidoudez, C; Parra, E A; Girguis, P R

    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.

  8. Evidence for an oxygen evolving iron-oxo-cerium intermediate in iron-catalysed water oxidation.

    PubMed

    Codolà, Zoel; Gómez, Laura; Kleespies, Scott T; Que, Lawrence; Costas, Miquel; Lloret-Fillol, Julio

    2015-01-22

    The non-haem iron complex α-[Fe(II)(CF3SO3)2(mcp)] (mcp=(N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)-1,2-cis-diaminocyclohexane) reacts with Ce(IV) to oxidize water to O2, representing an iron-based functional model for the oxygen evolving complex of photosystem II. Here we trap an intermediate, characterized by cryospray ionization high resolution mass spectrometry and resonance Raman spectroscopy, and formulated as [(mcp)Fe(IV)(O)(μ-O)Ce(IV)(NO3)3](+), the first example of a well-characterized inner-sphere complex to be formed in cerium(IV)-mediated water oxidation. The identification of this reactive Fe(IV)-O-Ce(IV) adduct may open new pathways to validate mechanistic notions of an analogous Mn(V)-O-Ca(II) unit in the oxygen evolving complex that is responsible for carrying out the key O-O bond forming step.

  9. Effects of green tea on iron accumulation and oxidative stress in livers of iron-challenged thalassemic mice.

    PubMed

    Saewong, T; Ounjaijean, S; Mundee, Y; Pattanapanyasat, K; Fucharoen, S; Porter, J B; Srichairatanakool, S

    2010-03-01

    Liver is affected by secondary iron overload in transfusions dependent b-thalassemia patients. The redox iron can generate reactive oxidants that damage biomolecules, leading to liver fibrosis and cirrhosis. Iron chelators are used to treat thalassemias to achieve negative iron balance and relieve oxidant-induced organ dysfunctions. Green tea (GT) (Camellia sinensis) catechins exhibit anti-oxidation, the inhibition of carcinogenesis, the detoxification of CYP2E1-catalyzed HepG2 cells and iron chelation. The purpose of this study was to investigate the effectiveness of GT in iron-challenged thalassemic mice. Heterozygous BKO type-thalassemia (BKO) mice (C57BL/6) experienced induced iron overload by being fed a ferrocene-supplemented diet (Fe diet) for 8 weeks, and by orally being given GT extract (300 mg/kg) and deferiprone (DFP) (50 mg/kg) for a further 8 weeks. Liver iron content (LIC) was analyzed by TPTZ colorimetric and Perl's staining techniques. Concentrations of liver reduced glutathione (GSH), collagen and malondialdehyde (MDA) were also measured. Dosages of the GT extract and DFP lowered LIC in the Fe diet-fed BKO mice effectively. The extract did not change any concentrations of liver glutathione, collagen and MDA in the BKO mice. Histochemical examination showed leukocyte infiltration in the near by hepatic portal vein and high iron accumulation in the livers of the iron-loaded BKO mice, however GT treatment lowered the elevated iron deposition. In conclusion, green tea inhibits or delays the deposition of hepatic iron in regularly iron-loaded thalassemic mice effectively. This will prevent the iron-induced generation of free radicals via Haber-Weiss and Fenton reactions, and consequently liver damage and fibrosis. Combined chelation with green tea would be investigated in beta-thalassemia patients with iron overload.

  10. Redox-dependent open and closed forms of the active site of the bacterial respiratory nitric-oxide reductase revealed by cyanide binding studies.

    PubMed

    Grönberg, Karin L C; Watmough, Nicholas J; Thomson, Andrew J; Richardson, David J; Field, Sarah J

    2004-04-23

    The bacterial respiratory nitric-oxide reductase (NOR) catalyzes the respiratory detoxification of nitric oxide in bacteria and Archaea. It is a member of the well known super-family of heme-copper oxidases but has a [heme Fe-non-heme Fe] active site rather than the [heme Fe-Cu(B)] active site normally associated with oxygen reduction. Paracoccus denitrificans NOR is spectrally characterized by a ligand-to-metal charge transfer absorption band at 595 nm, which arises from the high spin ferric heme iron of a micro-oxo-bridged [heme Fe(III)-O-Fe(III)] active site. On reduction of the nonheme iron, the micro-oxo bridge is broken, and the ferric heme iron is hydroxylated or hydrated, depending on the pH. At present, the catalytic cycle of NOR is a matter of much debate, and it is not known to which redox state(s) of the enzyme nitric oxide can bind. This study has used cyanide to probe the nature of the active site in a number of different redox states. Our observations suggest that the micro-oxo-bridged [heme Fe(III)-O-Fe(III)] active site represents a closed or resting state of NOR that can be opened by reduction of the non-heme iron.

  11. Evaluation of iron oxide nanoparticle biocompatibility.

    PubMed

    Hanini, Amel; Schmitt, Alain; Kacem, Kamel; Chau, François; Ammar, Souad; Gavard, Julie

    2011-01-01

    Nanotechnology is an exciting field of investigation for the development of new treatments for many human diseases. However, it is necessary to assess the biocompatibility of nanoparticles in vitro and in vivo before considering clinical applications. Our characterization of polyol-produced maghemite γ-Fe(2)O(3) nanoparticles showed high structural quality. The particles showed a homogeneous spherical size around 10 nm and could form aggregates depending on the dispersion conditions. Such nanoparticles were efficiently taken up in vitro by human endothelial cells, which represent the first biological barrier to nanoparticles in vivo. However, γ-Fe(2)O(3) can cause cell death within 24 hours of exposure, most likely through oxidative stress. Further in vivo exploration suggests that although γ-Fe(2)O(3) nanoparticles are rapidly cleared through the urine, they can lead to toxicity in the liver, kidneys and lungs, while the brain and heart remain unaffected. In conclusion, γ-Fe(2)O(3) could exhibit harmful properties and therefore surface coating, cellular targeting, and local exposure should be considered before developing clinical applications.

  12. Alleviation of iron induced oxidative stress by the grape fruit flavanone naringin in vitro.

    PubMed

    Jagetia, Ganesh Chandra; Reddy, Tiyagura Koti

    2011-04-25

    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. The protective effect of naringin, a grape fruit flavanone, was studied in iron overloaded isolated mouse liver mitochondria, where the isolated mitochondrial fraction was incubated with various concentrations of naringin before ferric ion loading. Iron overloading of mitochondrial fraction resulted in an increase in lipid peroxidation, protein oxidation, and DNA damage, whereas iron overload reduced the glutathione (GSH) concentration, glutathione-S-transferase (GST), glutathione peroxidase (GSHPx), catalase and superoxide dismutase (SOD) activities. Pretreatment of mitochondrial fraction with naringin inhibited iron-induced lipid peroxidation, protein oxidation, and DNA damage. Conversely, naringin supplementation arrested iron-induced depletion in the GSH contents, GSHPx, GST, SOD and catalase activities significantly. Ferric iron reduction assay revealed that naringin could not reduce ferric iron into ferrous iron indicating that it did not exhibit prooxidant activity. Iron free coordination site assay indicated that naringin was unable to occupy all the active sites of iron indicating that naringin did not completely chelate iron. Our study demonstrates that naringin was able to share the burden of endogenous oxidants by inhibiting the iron-induced depletion of all important antioxidant enzymes as well as GSH and may act as a good antioxidant.

  13. Particle interactions of polyvinylpyrrolidone-coated iron oxide particles as magnetic drug delivery agents

    NASA Astrophysics Data System (ADS)

    İşçi, Sevim; İşçi, Yavuz; Bekaroğlu, Maide Gökçe

    2017-08-01

    Iron oxide particles have been recently researched for the potential applications of targeted drug delivery due to their magnetic properties. The surfaces of the iron oxide particles must be modified to reduce the toxicity and to load the drug to the particles. Biopolymers are good surface modifiers of colloidal particles such as iron oxide particles. The degree of surface coverage of the colloidal iron oxide particles affects the stability, toxicity, magnetic properties and drug loading efficiency. In this study, the interactions of iron oxide (Fe3O4) particles and PVP were determined according to the colloidal properties. The proper concentration of PVP for the whole coverage of the iron oxide particles was found for the possible magnetic drug delivery applications by controlling the colloidal properties of the dispersions. The magnetic properties and toxicity of the fully covered bioiron oxide was also determined for possible applications.

  14. Evaluation of Characterization Techniques for Iron Pipe Corrosion Products and Iron Oxide Thin Films

    SciTech Connect

    Borch, Thomas; Camper, Anne K.; Biederman, Joel A.; Butterfield, Phillip; Gerlach, Robin; Amonette, James E.

    2008-10-01

    A common problem faced by drinking water studies is that of properly characterizing the corrosion products (CP) in iron pipescor synthetic Fe (hydr)oxides used to simulate the iron pipe used in municipal drinking-water systems. The present work compares the relative applicability of a suite of imaging and analytical techniques for the characterization of CPs and synthetic Fe oxide thin films and provide an overview of the type of data that each instrument can provide as well as their limitations to help researchers and consultants choose the best technique for a given task. Crushed CP from a water distribution system and synthetic Fe oxide thin films formed on glass surfaces were chosen as test samples for this evaluation. The CP and synthetic Fe oxide thin films were analyzed by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray powder diffractometry (XRD), grazing incident diffractometry (GID), transmission electron microscopy (TEM), selected area electron diffraction, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared, Mössbauer spectroscopy, Brunauer-Emmett-Teller N2 adsorption and Fe concentration was determined by the ferrozine method. XRD and GID were found to be the most suitable techniques for identification of the mineralogical composition of CP and synthetic Fe oxide thin films, respectively. AFM and a combined ToF-SIMS-AFM approach proved excellent for roughness and depth profiling analysis of synthetic Fe oxide thin films, respectively. Corrosion products were difficult to study by AFM due to their surface roughness, while synthetic Fe oxide thin films resisted most spectroscopic methods due to their limited thickness (118 nm). XPS analysis is not recommended for mixtures of Fe (hydr)oxides due to their spectral similarities. SEM and TEM provided great detail on mineralogical morphology.

  15. Accumulation of iron oxide nanoparticles by cultured primary neurons.

    PubMed

    Petters, Charlotte; Dringen, Ralf

    2015-02-01

    Magnetic iron oxide nanoparticles (IONPs) are frequently used for biomedical applications. Although nanoparticles can enter the brain, little is known so far on the uptake of IONPs in neurons and on their neurotoxic potential. Hence, we applied dimercaptosuccinate (DMSA)-coated IONPs to cultured primary rat cerebellar granule neurons. These IONPs had average hydrodynamic diameters of around 80 nm and 120 nm when dispersed in incubation medium in the absence and the presence of 10% fetal calf serum, respectively. Acute exposure of neurons with IONPs for up to 6 h did neither alter the cell morphology nor compromise cell viability, although neurons accumulated large amounts of IONPs in a time- and concentration-dependent manner which caused delayed toxicity. For the first 30 min of incubation of neurons at 37 °C with IONPs the cellular iron content increased proportionally to the concentration of IONPs applied irrespective of the absence and the presence of serum. IONP-exposure in the absence of serum generated maximal cellular iron contents of around 3000 nmol iron/mg protein after 4 h of incubation, while the accumulation in the presence of 10% serum was slower and reached already within 1 h maximal values of around 450 nmol iron/mg protein. For both incubation conditions was the increase in cellular iron contents significantly lowered by reducing the incubation temperature to 4 °C. Application of inhibitors of endocytotic pathways did not affect neuronal IONP accumulation in the absence of serum, while inhibitors of clathrin-mediated endocytosis lowered significantly the IONP accumulation in the presence of serum. These data demonstrate that DMSA-coated IONPs are not acutely toxic to cultured neurons and that a protein corona around the particles strongly affects their interaction with neurons. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Iron isotope fractionation during photo-oxidation of aqueous ferrous iron

    NASA Astrophysics Data System (ADS)

    Staton, S.; Amskold, L.; Gordon, G.; Anbar, A.; Konhauser, K.

    2006-05-01

    The classic interpretation of banded iron formations (BIFs) presumes the presence of dissolved O2 in the surface ocean to oxidize ferrous Fe. However, at least two alternative oxidation mechanisms are possible: UV photo-oxidation; and the activity of anaerobic Fe(II)-oxidizing photosynthetic bacteria. We are investigating Fe isotope fractionation as a means of differentiating amongst these mechanisms. Photo-oxidation has been examined at pH ~ 3 and 41°C in the absence of ligands other than H2O, OH-, and Cl- using UVA (316-400 nm) and UVC (200-280 nm) light sources. In these experiments, ferrous Fe was oxidized and precipitated as ferric oxyhydroxide. We find that isotopically heavy Fe was preferentially removed from solution. The fractionation factor (α) for the overall reaction is ~ 1.0025. This value is comparable to the α between Fe2+ and Fe3+ hexaquo complexes, but larger than the effect seen during the overall process of ferrous Fe oxidation and precipitation at near-neutral pH. The magnitude of isotope fractionation is likely to change at higher pH for two reasons. First, ferric oxyhydroxide precipitation, which may impart a kinetic isotope effect, is faster at higher pH. Second, the major UV-absorbing ferrous species in the ocean is the ferrous hydroxide ion [Fe(OH)+], the concentration of which is strongly pH dependent. Photo-oxidation experiments at realistic seawater pH are under current investigation.

  17. New Insight into Microbial Iron Oxidation as Revealed by the Proteomic Profile of an Obligate Iron-Oxidizing Chemolithoautotroph

    PubMed Central

    Emerson, David; Sylvan, Jason B.; Orcutt, Beth N.; Jacobson Meyers, Myrna E.; Ramírez, Gustavo A.; Zhong, John D.; Edwards, Katrina J.

    2015-01-01

    Microaerophilic, neutrophilic, iron-oxidizing bacteria (FeOB) grow via the oxidation of reduced Fe(II) at or near neutral pH, in the presence of oxygen, making them relevant in numerous environments with elevated Fe(II) concentrations. However, the biochemical mechanisms for Fe(II) oxidation by these neutrophilic FeOB are unknown, and genetic markers for this process are unavailable. In the ocean, microaerophilic microorganisms in the genus Mariprofundus of the class Zetaproteobacteria are the only organisms known to chemolithoautotrophically oxidize Fe and concurrently biomineralize it in the form of twisted stalks of iron oxyhydroxides. The aim of this study was to identify highly expressed proteins associated with the electron transport chain of microaerophilic, neutrophilic FeOB. To this end, Mariprofundus ferrooxydans PV-1 was cultivated, and its proteins were extracted, assayed for redox activity, and analyzed via liquid chromatography-tandem mass spectrometry for identification of peptides. The results indicate that a cytochrome c4, cbb3-type cytochrome oxidase subunits, and an outer membrane cytochrome c were among the most highly expressed proteins and suggest an involvement in the process of aerobic, neutrophilic bacterial Fe oxidation. Proteins associated with alternative complex III, phosphate transport, carbon fixation, and biofilm formation were abundant, consistent with the lifestyle of Mariprofundus. PMID:26092463

  18. New Insight into Microbial Iron Oxidation as Revealed by the Proteomic Profile of an Obligate Iron-Oxidizing Chemolithoautotroph.

    PubMed

    Barco, Roman A; Emerson, David; Sylvan, Jason B; Orcutt, Beth N; Jacobson Meyers, Myrna E; Ramírez, Gustavo A; Zhong, John D; Edwards, Katrina J

    2015-09-01

    Microaerophilic, neutrophilic, iron-oxidizing bacteria (FeOB) grow via the oxidation of reduced Fe(II) at or near neutral pH, in the presence of oxygen, making them relevant in numerous environments with elevated Fe(II) concentrations. However, the biochemical mechanisms for Fe(II) oxidation by these neutrophilic FeOB are unknown, and genetic markers for this process are unavailable. In the ocean, microaerophilic microorganisms in the genus Mariprofundus of the class Zetaproteobacteria are the only organisms known to chemolithoautotrophically oxidize Fe and concurrently biomineralize it in the form of twisted stalks of iron oxyhydroxides. The aim of this study was to identify highly expressed proteins associated with the electron transport chain of microaerophilic, neutrophilic FeOB. To this end, Mariprofundus ferrooxydans PV-1 was cultivated, and its proteins were extracted, assayed for redox activity, and analyzed via liquid chromatography-tandem mass spectrometry for identification of peptides. The results indicate that a cytochrome c4, cbb3-type cytochrome oxidase subunits, and an outer membrane cytochrome c were among the most highly expressed proteins and suggest an involvement in the process of aerobic, neutrophilic bacterial Fe oxidation. Proteins associated with alternative complex III, phosphate transport, carbon fixation, and biofilm formation were abundant, consistent with the lifestyle of Mariprofundus.

  19. Comparison of the Effects of Iron Oxide, as a New Form of Iron Supplement, and Ferrous Sulfate on the Blood Levels of Iron and Total Iron-Binding Globulin in the Rabbit.

    PubMed

    Kheiri, Reyhaneh; Koohi, Mohammad Kazem; Sadeghi-Hashjin, Goudarz; Nouri, Hadiseh; Khezli, Noushin; Hassan, Mohsen Aghamohammad; Hoomani, Fatemeh; Shams, Gholamreza; Rasouli, Ali; Motaghinejad, Majid

    2017-01-01

    Iron oxide is an important biological agent that has a key role in medical processes; however, the mechanism whereby it provides iron for human and animal cells and its biological uses remains unclear. We aimed to evaluate the effects of oral iron oxide on serum iron status and compare the results with those of iron sulfate as a reference salt. Fifteen adult rabbits were divided into 3 groups of 5 each: control group, iron sulfate group, and iron oxide group. The groups received doses of 3.3, 10, and 33 mg/kg in 3 experiments. Venous blood samples were obtained just before the oral administration of iron sulfate and iron oxide (3.3 mg/kg). More blood samples were taken 3 times at the time points of 1, 6, and 12 hours after the administration of the solutions. Serum was separated for the measurement of iron (Fe) and total iron-binding globulin (TIBG) with routine methods. One week later, the same experiment was repeated with 10 mg/kg of iron sulfate and iron oxide; and 1 week later after the second experiment, again the same experiment was repeated with 33 mg/kg of iron sulfate and iron oxide. The results showed that 33 mg/kg of iron sulfate 1 hour after treatment caused a significant difference in the Fe and TIBG levels between all the groups (P=0.014 for Fe and P=0.027 for TIBG). Our data showed that the absorption of iron oxide was similar to that of ferrous sulfate and in high doses was as useful as iron supplement.

  20. Comparison of the Effects of Iron Oxide, as a New Form of Iron Supplement, and Ferrous Sulfate on the Blood Levels of Iron and Total Iron-Binding Globulin in the Rabbit

    PubMed Central

    Kheiri, Reyhaneh; Koohi, Mohammad Kazem; Sadeghi-Hashjin, Goudarz; Nouri, Hadiseh; Khezli, Noushin; Hassan, Mohsen Aghamohammad; Hoomani, Fatemeh; Shams, Gholamreza; Rasouli, Ali; Motaghinejad, Majid

    2017-01-01

    Iron oxide is an important biological agent that has a key role in medical processes; however, the mechanism whereby it provides iron for human and animal cells and its biological uses remains unclear. We aimed to evaluate the effects of oral iron oxide on serum iron status and compare the results with those of iron sulfate as a reference salt. Fifteen adult rabbits were divided into 3 groups of 5 each: control group, iron sulfate group, and iron oxide group. The groups received doses of 3.3, 10, and 33 mg/kg in 3 experiments. Venous blood samples were obtained just before the oral administration of iron sulfate and iron oxide (3.3 mg/kg). More blood samples were taken 3 times at the time points of 1, 6, and 12 hours after the administration of the solutions. Serum was separated for the measurement of iron (Fe) and total iron-binding globulin (TIBG) with routine methods. One week later, the same experiment was repeated with 10 mg/kg of iron sulfate and iron oxide; and 1 week later after the second experiment, again the same experiment was repeated with 33 mg/kg of iron sulfate and iron oxide. The results showed that 33 mg/kg of iron sulfate 1 hour after treatment caused a significant difference in the Fe and TIBG levels between all the groups (P=0.014 for Fe and P=0.027 for TIBG). Our data showed that the absorption of iron oxide was similar to that of ferrous sulfate and in high doses was as useful as iron supplement. PMID:28293054

  1. Ceruloplasmin protects injured spinal cord from iron-mediated oxidative damage.

    PubMed

    Rathore, Khizr I; Kerr, Bradley J; Redensek, Adriana; López-Vales, Rubèn; Jeong, Suh Young; Ponka, Prem; David, Samuel

    2008-11-26

    CNS injury-induced hemorrhage and tissue damage leads to excess iron, which can cause secondary degeneration. The mechanisms that handle this excess iron are not fully understood. We report that spinal cord contusion injury (SCI) in mice induces an "iron homeostatic response" that partially limits iron-catalyzed oxidative damage. We show that ceruloplasmin (Cp), a ferroxidase that oxidizes toxic ferrous iron, is important for this process. SCI in Cp-deficient mice demonstrates that Cp detoxifies and mobilizes iron and reduces secondary tissue degeneration and functional loss. Our results provide new insights into how astrocytes and macrophages handle iron after SCI. Importantly, we show that iron chelator treatment has a delayed effect in improving locomotor recovery between 3 and 6 weeks after SCI. These data reveal important aspects of the molecular control of CNS iron homeostasis after SCI and suggest that iron chelator therapy may improve functional recovery after CNS trauma and hemorrhagic stroke.

  2. Iron deficiency suppresses ileal nitric oxide synthase activity.

    PubMed

    Goldblatt, M I; Choi, S H; Swartz-Basile, D A; Nakeeb, A; Sarna, S K; Pitt, H A

    2001-01-01

    Intestinal motility disorders are more common in women of childbearing age who are prone to iron deficiency anemia. The neurotransmitters nitric oxide (NO) and acetylcholine (ACh) play a key role in ileal smooth muscle relaxation and contraction, respectively. Iron-containing heme is known to be a cofactor for nitric oxide synthase (NOS), the enzyme responsible for NO production. Therefore we tested the hypothesis that iron deficiency would downregulate ileal NOS activity without affecting the ileum's response to ACh. Twelve adult female prairie dogs were fed either an iron-supplemented (Fe+) (200 ppm) (n = 6) or an iron-deficient (Fe-) (8 ppm) (n = 6) diet for 8 weeks. Ileal circular muscle strips were harvested to measure responses to ACh and electrical field stimulation. Under nonadrenergic noncholinergic (NANC) conditions, Nomega-nitro-L-arginine (L-NNA), an NOS inhibitor, and VIP(10-28), a vasoactive intestinal peptide (VIP) inhibitor, were added prior to electrical field stimulation. NANC inhibitory responses are expressed as a percentage of optimal relaxation from EDTA. The excitatory response to ACh was similar in both groups (1.1 +/- 0.3 N/cm(2) vs. 1.5 +/- 0.3 N/cm(2), P = 0.45). The inhibitory response to electrical field stimulation under NANC conditions was greater in the Fe+ group (34.7 +/- 2.9%) compared to the Fe- group (23.9 +/- 3.2%; P<0.01). L-NNA eliminated the inhibitory response in the Fe+ group (0.02 +/- 0.02%) but not in the Fe- group (8.38 +/- 2.15%; P <0.01). VIP(10-28) led to greater relaxation in the Fe+ animals (45.8 +/- 6.6%) than in the Fe- animals (23.4 +/- 5.8%; P <0.05). Both L-NNA and VIP(10-28) had no inhibitory response (0.02 +/- 0.02%) in the Fe+ animals, whereas the Fe- animals had some residual inhibition (2.54 +/- 1.04%; P <0.05). These data suggest that ileal NANC relaxation is due to NOS and that iron deficiency results in (1) decreased NANC relaxation, (2) a compensatory relaxation due to a non-NOS, non-VIP mechanism, and

  3. Crystal structure of iron-oxide nanoparticles synthesized from ferritin

    NASA Astrophysics Data System (ADS)

    Krispin, Michael; Ullrich, Aladin; Horn, Siegfried

    2012-02-01

    We have investigated the crystal structure of nanosized iron-oxide by X-ray diffraction (XRD), extended X-ray absorption fine structure measurements at the iron K-edge as well as by transmission electron microscopy (TEM). Iron-oxide nanoparticles were produced by thermal treatment of horse spleen ferritin molecules. The structure of these particles was compared to α-Fe2O3 and γ-Fe2O3 nanopowder references. The thermal treatment of a submonolayer film of ferritin molecules results in pure γ-Fe2O3 nanoparticles, while for films above a certain thickness α-Fe2O3 and γ-Fe2O3 coexist, exhibiting two different crystallite sizes. TEM shows a characteristic particle diameter of 7 nm for γ-Fe2O3 resulting from thermal treatment of monolayers, consistent with the crystallite size of the γ-phase as obtained from XRD measurements on multi-layered samples. XRD shows the α-Fe2O3 phase to be characterized by a crystallite size of 34 nm.

  4. Mercury removal in wastewater by iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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, Fe3O4 and γ-Fe2O3 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 λmax∼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.

  5. Reductive dechlorination of chlorinated solvents by zero-valent iron, iron oxide and iron sulfide minerals

    SciTech Connect

    Sivavec, T.M.; Horney, D.P.

    1996-10-01

    The degradation of chlorinated solvents by reduction at the surface of zero-valent metals and bimetallic systems has emerged as an important approach to the in-situ remediation of ground water. Reduction by iron metal was studied in batch and column systems to develop a mechanistic understanding of the reaction chemistry and to determine the factors that affect dechlorination rate and long term performance in field applications.

  6. Synthesis and Reactive Properties of Iron Oxide-Coated Nanoaluminum

    NASA Astrophysics Data System (ADS)

    Kaplowitz, Daniel A.; Jian, Guoqiang; Gaskell, Karen; Jacob, Rohit; Zachariah, Michael R.

    2014-04-01

    A homogeneous coating of Fe3O4 on in situ-generated nanoaluminum was accomplished by thermal decomposition of Fe(CO)5 in an aluminum aerosol stream and subsequent oxidation of iron by air bleed. X-ray photoelectron spectroscopy (XPS) investigation revealed that oxygen penetrated through this coating, and Fe3O4 facilitated the formation of an expanded aluminum oxide layer compared to an uncoated aluminum case. Closed cell combustion tests displayed a minor decrease in pressure response for the coated product, which was attributed to the increased aluminum oxide layer. The critical ignition temperature was reduced for the coated product in T-jump fine-wire combustion tests.

  7. Low-temperature formation of magnetic iron oxides

    NASA Technical Reports Server (NTRS)

    Koch, Chr. Bender; Madsen, M. B.

    1992-01-01

    Elemental analysis and magnetic measurements of the surface of Mars have indicated the presence of an iron oxide with a considerable magnetic moment. Identification of the oxide phase(s) is an important subject as this may be used to identify the process of weathering on the martian surface as well as the composition of the Mars regolith itself. Consequently, interest was in evidence of new formation of strongly magnetic phases (e.g., magnetite, maghemite, feroxyhyte) in terrestrially derived Mars sample analogs. Within the group of Mars sample analogs derived from low-temperature weathering of basalts in Arctic regions, evidence of magnetic oxides formed at the outermost weathering rind was never observed. However, in one instance where the weathering products accumulating in a crack of a basaltic stone were investigated, evidence of magnetite was found. The experimental details are presented.

  8. Low-temperature formation of magnetic iron oxides

    NASA Technical Reports Server (NTRS)

    Koch, Chr. Bender; Madsen, M. B.

    1992-01-01

    Elemental analysis and magnetic measurements of the surface of Mars have indicated the presence of an iron oxide with a considerable magnetic moment. Identification of the oxide phase(s) is an important subject as this may be used to identify the process of weathering on the martian surface as well as the composition of the Mars regolith itself. Consequently, interest was in evidence of new formation of strongly magnetic phases (e.g., magnetite, maghemite, feroxyhyte) in terrestrially derived Mars sample analogs. Within the group of Mars sample analogs derived from low-temperature weathering of basalts in Arctic regions, evidence of magnetic oxides formed at the outermost weathering rind was never observed. However, in one instance where the weathering products accumulating in a crack of a basaltic stone were investigated, evidence of magnetite was found. The experimental details are presented.

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

    NASA Astrophysics Data System (ADS)

    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

  10. Pulsed-laser deposition of nanostructured iron oxide catalysts for efficient water oxidation.

    PubMed

    Orlandi, Michele; Caramori, Stefano; Ronconi, Federico; Bignozzi, Carlo A; El Koura, Zakaria; Bazzanella, Nicola; Meda, Laura; Miotello, Antonio

    2014-05-14

    Amorphous iron oxide nanoparticles were synthesized by pulsed-laser deposition (PLD) for functionalization of indium-tin oxide surfaces, resulting in electrodes capable of efficient catalysis in water oxidation. These electrodes, based on earth-abundant and nonhazardous iron metal, are able to sustain high current densities (up to 20 mA/cm2) at reasonably low applied potential (1.64 V at pH 11.8 vs reversible hydrogen electrode) for more than 1 h when employed as anodes for electrochemical water oxidation. The good catalytic performance proves the validity of PLD as a method to prepare nanostructured solid-state materials for catalysis, enabling control over critical properties such as surface coverage and morphology.

  11. GAS-PHASE FLAME SYNTHESIS AND PROPERTIES OF MAGNETIC IRON OXIDE NANOPARTICLES WITH REDUCED OXIDATION STATE

    PubMed Central

    Kumfer, Benjamin M; Shinoda, Kozo; Jeyadevan, Balachandran; Kennedy, Ian M

    2010-01-01

    Iron oxide nanoparticles of reduced oxidation state, mainly in the form of magnetite, have been synthesized utilizing a new continuous, gas-phase, nonpremixed flame method using hydrocarbon fuels. This method takes advantage of the characteristics of the inverse flame, which is produced by injection of oxidizer into a surrounding flow of fuel. Unlike traditional flame methods, this configuration allows for the iron particle formation to be maintained in a more reducing environment. The effects of flame temperature, oxygen-enrichment and fuel dilution (i.e. the stoichiometric mixture fraction), and fuel composition on particle size, Fe oxidation state, and magnetic properties are evaluated and discussed. The crystallite size, Fe(II) fraction, and saturation magnetization were all found to increase with flame temperature. Flames of methane and ethylene were used, and the use of ethylene resulted in particles containing metallic Fe(0), in addition to magnetite, while no Fe(0) was present in samples synthesized using methane. PMID:20228941

  12. Anoxic photochemical oxidation of siderite generates molecular hydrogen and iron oxides

    PubMed Central

    Kim, J. Dongun; Yee, Nathan; Nanda, Vikas; Falkowski, Paul G.

    2013-01-01

    Photochemical reactions of minerals are underappreciated processes that can make or break chemical bonds. We report the photooxidation of siderite (FeCO3) by UV radiation to produce hydrogen gas and iron oxides via a two-photon reaction. The calculated quantum yield for the reaction suggests photooxidation of siderite would have been a significant source of molecular hydrogen for the first half of Earth’s history. Further, experimental results indicate this abiotic, photochemical process may have led to the formation of iron oxides under anoxic conditions. The reaction would have continued through the Archean to at least the early phases of the Great Oxidation Event, and provided a mechanism for oxidizing the atmosphere through the loss of hydrogen to space, while simultaneously providing a key reductant for microbial metabolism. We propose that the photochemistry of Earth-abundant minerals with wide band gaps would have potentially played a critical role in shaping the biogeochemical evolution of early Earth. PMID:23733945

  13. Selective Inhibition of the Oxidation of Ferrous Iron or Sulfur in Thiobacillus ferrooxidans

    PubMed Central

    Harahuc, Lesia; Lizama, Hector M.; Suzuki, Isamu

    2000-01-01

    The oxidation of either ferrous iron or sulfur by Thiobacillus ferrooxidans was selectively inhibited or controlled by various anions, inhibitors, and osmotic pressure. Iron oxidation was more sensitive than sulfur oxidation to inhibition by chloride, phosphate, and nitrate at low concentrations (below 0.1 M) and also to inhibition by azide and cyanide. Sulfur oxidation was more sensitive than iron oxidation to the inhibitory effect of high osmotic pressure. These differences were evident not only between iron oxidation by iron-grown cells and sulfur oxidation by sulfur-grown cells but also between the iron and sulfur oxidation activities of the same iron-grown cells. Growth experiments with ferrous iron or sulfur as an oxidizable substrate confirmed the higher sensitivity of iron oxidation to inhibition by phosphate, chloride, azide, and cyanide. Sulfur oxidation was actually stimulated by 50 mM phosphate or chloride. Leaching of Fe and Zn from pyrite (FeS2) and sphalerite (ZnS) by T. ferrooxidans was differentially affected by phosphate and chloride, which inhibited the solubilization of Fe without significantly affecting the solubilization of Zn. PMID:10698768

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

    PubMed

    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.

  15. The effect of cationic polymer treatment on adhesion of iron oxide to eyelashes.

    PubMed

    Ko, S; Roh, Y H; Choo, J H; Jang, S H; Han, S H; Jang, H G

    2009-01-01

    The aim of this study was to investigate the effect of iron oxide application on improving the volume of eyelashes. Iron oxide, having a negative surface charge in its natural form, was coated with commercial cationic polymers to increase its adhesion. The iron oxides coated with different types and concentrations of these polymers were incorporated into a basic mascara formula to test their volume effects by means of the weight difference of eyelashes.The results indicated that the type and concentration of coating materials affect the surface zeta potential and particle cluster size of iron oxides. The type of cationic polymer, especially, was shown to modify both factors of iron oxide. The obtained results also suggested that the volume effect of mascara increases with a higher positive surface zeta potential and a smaller particle cluster size of the coated iron oxides.

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

    PubMed

    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.

  17. Magnetic characteristics of iron-modified oxide layers on titanium

    NASA Astrophysics Data System (ADS)

    Rudnev, V. S.; Adigamova, M. V.; Lukiyanchuk, I. V.; Tkachenko, I. A.; Morozova, V. P.; Ustinov, A. Yu.; Kharitonskii, P. V.; Frolov, A. M.

    2014-12-01

    Iron-modified TiO2 coatings on titanium exhibiting ferromagnetic properties are formed by combining plasma electrolytic oxidation (PEO) and impregnation with subsequent annealing. It is found that iron is contained in the composition of dispersed particles with sizes of 1-10 μm distributed over the surface of the coatings. It is shown that the coercive force of the coating on titanium samples is 20-70 Oe. The composition, structure, and magnetic properties of the samples with coatings prepared via direct PEO and by combining PEO and impregnation are compared. It is concluded that impregnation and annealing procedures can be used to impart ferromagnetic properties to PEO coatings with different compositions, e.g., protective coatings and coatings applied in catalysis or medicine.

  18. In Vivo Clearance and Toxicity of Monodisperse Iron Oxide Nanocrystals

    PubMed Central

    Gu, Luo; Fang, Ronnie H.; Sailor, Michael J.; Park, Ji-Ho

    2012-01-01

    Thermal decomposition of organometallic precursors have been found to generate highly crystalline iron oxide (IO) nanocrystals that display superior MR contrast and lower polydispersity than IO nanocrystals synthesized by aqueous precipitation. In the present study, the in vivo characteristics of IO nanocrystals prepared by the thermal decomposition route and then coated with a phospholipid containing a pendant poly(ethylene glycol) chain are examined. The size and surface chemistry of the IO nanocrystal influences the biodistibution, the rate of biodegradation and bioclearance, and the biodegradation products. We conclude that the in vivo fate of PEGylated monodisperse IO nanocrystals and the iron, phospholipid, and oleic acid biodegradation products may influence the cellular environments in the organs and blood that can determine their safety in the body. PMID:22646927

  19. Hydrophilic Packaging of Iron Oxide Nanoclusters for Highly Sensitive Imaging

    PubMed Central

    Smith, Cartney E.; Ernenwein, Dawn; Shkumatov, Artem; Clay, Nicholas; Lee, JuYeon; Melhem, Molly; Misra, Sanjay; Zimmerman, Steven C.; Kong, Hyunjoon

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are used as imaging probes to provide contrast in magnetic resonance images. Successful use of SPIONs in targeted applications greatly depends on their ability to generate contrast, even at low levels of accumulation, in the tissue of interest. In the present study, we report that SPION nanoclusters packaged to a controlled size by a hyperbranched polyglycerol (HPG) can target tissue defects and have a high relaxivity of 719 mM−1s−1, which was close to their theoretical maximal limit. The resulting nanoclusters were able to identify regions of defective vasculature in an ischemic murine hindlimb using MRI with iron doses that were 5–10 fold lower than those typically used in preclinical studies. Such high relaxivity was attributed to the molecular architecture of HPG, which mimics that of the water retentive polysaccharide, glycogen. The results of this study will be broadly useful in sensitive imaging applications. PMID:26291408

  20. Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps.

    PubMed

    Sivan, Orit; Antler, Gilad; Turchyn, Alexandra V; Marlow, Jeffrey J; Orphan, Victoria J

    2014-10-07

    Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with (13)C-labeled methane showed co-occurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organic carbon oxidation or in diffusive sedimentary sulfate-methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. These results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling.

  1. Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps

    PubMed Central

    Sivan, Orit; Antler, Gilad; Turchyn, Alexandra V.; Marlow, Jeffrey J.; Orphan, Victoria J.

    2014-01-01

    Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with 13C-labeled methane showed co-occurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organic carbon oxidation or in diffusive sedimentary sulfate–methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. These results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling. PMID:25246590

  2. Nitric oxide, nitrosyl iron complexes, ferritin and frataxin: a well equipped team to preserve plant iron homeostasis.

    PubMed

    Ramirez, Leonor; Simontacchi, Marcela; Murgia, Irene; Zabaleta, Eduardo; Lamattina, Lorenzo

    2011-11-01

    Iron is a key element in plant nutrition. Iron deficiency as well as iron overload results in serious metabolic disorders that affect photosynthesis, respiration and general plant fitness with direct consequences on crop production. More than 25% of the cultivable land possesses low iron availability due to high pH (calcareous soils). Plant biologists are challenged by this concern and aimed to find new avenues to ameliorate plant responses and keep iron homeostasis under control even at wide range of iron availability in various soils. For this purpose, detailed knowledge of iron uptake, transport, storage and interactions with cellular compounds will help to construct a more complete picture of its role as essential nutrient. In this review, we summarize and describe the recent findings involving four central players involved in keeping cellular iron homeostasis in plants: nitric oxide, ferritin, frataxin and nitrosyl iron complexes. We attempt to highlight the interactions among these actors in different scenarios occurring under iron deficiency or iron overload, and discuss their counteracting and/or coordinating actions leading to the control of iron homeostasis.

  3. Chitosan-Iron Oxide Coated Graphene Oxide Nanocomposite Hydrogel: A Robust and Soft Antimicrobial Biofilm.

    PubMed

    Konwar, Achyut; Kalita, Sanjeeb; Kotoky, Jibon; Chowdhury, Devasish

    2016-08-17

    We report a robust biofilm with antimicrobial properties fabricated from chitosan-iron oxide coated graphene oxide nanocomposite hydrogel. For the first time, the coprecipitation method was used for the successful synthesis of iron oxide coated graphene oxide (GIO) nanomaterial. After this, films were fabricated by the gel-casting technique aided by the self-healing ability of the chitosan hydrogel network system. Both the nanomaterial and the nanocomposite films were characterized by techniques such as scanning electron microscopy, FT-IR spectroscopy, X-ray diffraction, and vibrating sample magnetometry. Measurements of the thermodynamic stability and mechanical properties of the films indictaed a significant improvement in their thermal and mechanical properties. Moreover, the stress-strain profile indicated the tough nature of the nanocomposite hydrogel films. These improvements, therefore, indicated an effective interaction and good compatibility of the GIO nanomaterial with the chitosan hydrogel matrix. In addition, it was also possible to fabricate films with tunable surface properties such as hydrophobicity simply by varying the loading percentage of GIO nanomaterial in the hydrogel matrix. Fascinatingly, the chitosan-iron oxide coated graphene oxide nanocomposite hydrogel films displayed significant antimicrobial activities against both Gram-positive and Gram-negative bacterial strains, such as methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, and Escherichia coli, and also against the opportunistic dermatophyte Candida albicans. The antimicrobial activities of the films were tested by agar diffusion assay and antimicrobial testing based on direct contact. A comparison of the antimicrobial activity of the chitosan-GIO nanocomposite hydrogel films with those of individual chitosan-graphene oxide and chitosan-iron oxide nanocomposite films demonstrated a higher antimicrobial activity for the former in both types of tests. In vitro hemolysis

  4. VEGF-Iron Oxide Conjugate for Dual MR and PET Imaging of Breast Cancer Angiogenesis

    DTIC Science & Technology

    2007-09-01

    iron oxide nanoparticles conjugated with macrocyclic chelating agent DOTA for 64Cu-labeling and cyclic RGD peptide for integrin alpha (v)beta(3...Nanoparticles We have developed two types of novel superparamagentic iron oxide nanoparticles (USPIO), namely, PVP -IO and PASP-IO...Polyvinylpyrrolidone ( PVP )-coated iron oxide ( PVP -IO) nanoparticles were synthesized by a one-step thermal decomposition method (Fig. 3). The overall size of the

  5. Greenlighting Photoelectrochemical Oxidation of Water by Iron Oxide

    SciTech Connect

    Kim, Dong Wook; Riha, Shannon C.; DeMarco, Erica J.; Martinson, Alex B. F.; Farha, Omar K.; Hupp, Joseph T.

    2014-12-23

    Hematite (alpha-Fe2O3) is one of just a few candidate electrode materials that possess all of the following photocatalyst-essential properties for scalable application to water oxidation: excellent stability, earth-abundance, suitability positive valence-band-edge energy, and significant visible light absorptivity. Despite these merits, hematites modest oxygen evolution reaction kinetics and its poor efficiency in delivering photogenerated holes, especially holes generated by green photons, to the electrode/solution interface, render it ineffective as a practical water-splitting catalyst. Here we show that hole delivery and catalytic utilization can be substantially improved through Ti alloying, provided that the alloyed material is present in ultrathin-thin-film form. Notably, the effects are most pronounced for charges photogenerated by photons with energy comparable to the band gap for excitation of Fe(3d) -> Fe(3d) transitions (i.e., green photons). Additionally, at the optimum Ti substitution level the lifetimes of surface-localized holes, competent for water oxidation, are extended. Together these changes explain an overall improvement in photoelectrochemical performance, especially enhanced internal quantum efficiencies, observed upon Ti(IV) incorporation.

  6. Greenlighting photoelectrochemical oxidation of water by iron oxide.

    PubMed

    Kim, Dong Wook; Riha, Shannon C; DeMarco, Erica J; Martinson, Alex B F; Farha, Omar K; Hupp, Joseph T

    2014-12-23

    Hematite (α-Fe2O3) is one of just a few candidate electrode materials that possess all of the following photocatalyst-essential properties for scalable application to water oxidation: excellent stability, earth-abundance, suitability positive valence-band-edge energy, and significant visible light absorptivity. Despite these merits, hematite's modest oxygen evolution reaction kinetics and its poor efficiency in delivering photogenerated holes, especially holes generated by green photons, to the electrode/solution interface, render it ineffective as a practical water-splitting catalyst. Here we show that hole delivery and catalytic utilization can be substantially improved through Ti alloying, provided that the alloyed material is present in ultrathin-thin-film form. Notably, the effects are most pronounced for charges photogenerated by photons with energy comparable to the band gap for excitation of Fe(3d)→Fe(3d) transitions (i.e., green photons). Additionally, at the optimum Ti substitution level the lifetimes of surface-localized holes, competent for water oxidation, are extended. Together these changes explain an overall improvement in photoelectrochemical performance, especially enhanced internal quantum efficiencies, observed upon Ti(IV) incorporation.

  7. Neurobehavioural Toxicity of Iron Oxide Nanoparticles in Mice.

    PubMed

    Dhakshinamoorthy, Vasanth; Manickam, Vijayprakash; Perumal, Ekambaram

    2017-08-01

    Iron oxide nanoparticles (Fe2O3-NPs) are widely used in various biomedical applications, extremely in neurotheranostics. Simultaneously, Fe2O3-NP usage is of alarming concern, as its exposure to living systems causes deleterious effects due to its redox potential. However, study on the neurobehavioural impacts of Fe2O3-NPs is very limited. In this regard, adult male mice were intraperitoneally administered with Fe2O3-NPs (25 and 50 mg/kg body weight) once a week for 4 weeks. A significant change in locomotor behaviour and spatial memory was observed in Fe2O3-NP-treated animals. Damages to blood-brain barrier permeability by Fe2O3-NPs and their accumulation in brain regions were evidenced by Evan's blue staining, iron estimation and Prussian blue staining. Elevated nitric oxide, acetylcholinesterase, lactate dehydrogenase leakage and demyelination were observed in the Fe2O3-NP-exposed brain tissues. Imbalanced levels of ROS generation and antioxidant defence mechanism (superoxide dismutase and catalase) cause damages to lipids, proteins and DNA. PARP and cleaved caspase 3 expression levels were found to be increased in the Fe2O3-NP-exposed brain regions which confirms DNA damage and apoptosis. Thus, repeated Fe2O3-NP exposure causes neurobehavioural impairments by nanoparticle accumulation, oxidative stress and apoptosis in the mouse brain.

  8. From iron oxide nanoparticles towards advanced iron-based inorganic materials designed for biomedical applications.

    PubMed

    Figuerola, Albert; Di Corato, Riccardo; Manna, Liberato; Pellegrino, Teresa

    2010-08-01

    In the last decade the progress achieved on the synthesis of inorganic nanostructures has been accompanied by the parallel exploitation of these systems in various fields, among them are biology and medicine. We provide here an overview of the iron-based inorganic nanostructured materials that have been developed and tested in these fields. We will highlight the major concepts on the preparation, physical properties and applications of such nanostructures, starting from the most investigated iron oxide nanoparticles. We will describe then the new generation of inorganic hybrid nanostructures, which are structures that integrate in each nano-object multiple inorganic nanocrystals of different materials. In our discussion we will focus on those works that have provided a sound proof of concept on the potential of the various systems as diagnostic and therapeutic agents. Copyright 2010 Elsevier Ltd. All rights reserved.

  9. Exhaled nitric oxide in acute respiratory syncytial virus bronchiolitis.

    PubMed

    Gadish, Tal; Soferman, Ruth; Merimovitch, Tamar; Fireman, Elizabeth; Sivan, Yakov

    2010-08-01

    To investigate fractional exhaled nitric oxide (FeNO) levels in infants during acute respiratory syncytial virus (RSV) bronchiolitis and during convalescence. Prospective cohort study. Comparison of FeNO levels between infants with laboratory-confirmed acute RSV bronchiolitis and 2 control groups: healthy infants and infants with recurrent wheezing. The Department of Pediatric Emergency Medicine and the Pediatric Pulmonary Clinic of the Tel Aviv Medical Center from November 2008 to July 2009. The FeNO levels were measured at referral and at 2 visits over 4 months after convalescence. The FeNO level was measured using the multiple-breath exhalation technique. Forty-four infants with acute RSV bronchiolitis (mean [SD] age, 6.8 [7.3] months), 21 infants with recurrent wheezing (mean [SD] age, 10.8 [7.59] months), and 32 age-matched healthy controls (mean [SD] age, 6.8 [9.1] months). Follow-up data were available for 22 children (55%) for the first follow-up visit and for 11 children (25%) for the second follow-up visit. Acute RSV bronchiolitis. The FeNO levels during acute RSV bronchiolitis vs controls and FeNO levels during follow-up vs acute-stage disease. Mean FeNO levels for RSV-positive infants were significantly lower compared with healthy controls and infants with recurrent wheezing: mean (SD), 1.89 (1.76) parts per billion (ppb), 7.28 (4.96) ppb, and 4.86 (7.49) ppb, respectively (P<.001). The FeNO levels at the 2- and 4-month follow-up visits increased to 7.74 (5.13) ppb and 11.37 (6.29) ppb, respectively (P=.001). The FeNO levels are temporarily reduced during acute RSV bronchiolitis and increase during convalescence to normal levels and higher. The mechanisms for this suppression and its relation to future wheezing and asthma need to be studied.

  10. Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers

    PubMed Central

    Wahajuddin; Arora, Sumit

    2012-01-01

    A targeted drug delivery system is the need of the hour. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the principle behind the development of superparamagnetic iron oxide nanoparticles (SPIONs) as novel drug delivery vehicles. SPIONs are small synthetic γ-Fe2O3 (maghemite) or Fe3O4 (magnetite) particles with a core ranging between 10 nm and 100 nm in diameter. These magnetic particles are coated with certain biocompatible polymers, such as dextran or polyethylene glycol, which provide chemical handles for the conjugation of therapeutic agents and also improve their blood distribution profile. The current research on SPIONs is opening up wide horizons for their use as diagnostic agents in magnetic resonance imaging as well as for drug delivery vehicles. Delivery of anticancer drugs by coupling with functionalized SPIONs to their targeted site is one of the most pursued areas of research in the development of cancer treatment strategies. SPIONs have also demonstrated their efficiency as nonviral gene vectors that facilitate the introduction of plasmids into the nucleus at rates multifold those of routinely available standard technologies. SPION-induced hyperthermia has also been utilized for localized killing of cancerous cells. Despite their potential biomedical application, alteration in gene expression profiles, disturbance in iron homeostasis, oxidative stress, and altered cellular responses are some SPION-related toxicological aspects which require due consideration. This review provides a comprehensive understanding of SPIONs with regard to their method of preparation, their utility as drug delivery vehicles, and some concerns which need to be resolved before they can be moved from bench top to bedside. PMID:22848170

  11. Arsenic Bioremediation by Biogenic Iron Oxides and Sulfides

    PubMed Central

    Couture, Raoul-Marie; Van Cappellen, Philippe; Corkhill, Claire L.; Charnock, John M.; Polya, David A.; Vaughan, David; Vanbroekhoven, Karolien; Lloyd, Jonathan R.

    2013-01-01

    Microcosms containing sediment from an aquifer in Cambodia with naturally elevated levels of arsenic in the associated groundwater were used to evaluate the effectiveness of microbially mediated production of iron minerals for in situ As remediation. The microcosms were first incubated without amendments for 28 days, and the release of As and other geogenic chemicals from the sediments into the aqueous phase was monitored. Nitrate or a mixture of sulfate and lactate was then added to stimulate biological Fe(II) oxidation or sulfate reduction, respectively. Without treatment, soluble As concentrations reached 3.9 ± 0.9 μM at the end of the 143-day experiment. However, in the nitrate- and sulfate-plus-lactate-amended microcosms, soluble As levels decreased to 0.01 and 0.41 ± 0.13 μM, respectively, by the end of the experiment. Analyses using a range of biogeochemical and mineralogical tools indicated that sorption onto freshly formed hydrous ferric oxide (HFO) and iron sulfide mineral phases are the likely mechanisms for As removal in the respective treatments. Incorporation of the experimental results into a one-dimensional transport-reaction model suggests that, under conditions representative of the Cambodian aquifer, the in situ precipitation of HFO would be effective in bringing groundwater into compliance with the World Health Organization (WHO) provisional guideline value for As (10 ppb or 0.13 μM), although soluble Mn release accompanying microbial Fe(II) oxidation presents a potential health concern. In contrast, production of biogenic iron sulfide minerals would not remediate the groundwater As concentration below the recommended WHO limit. PMID:23666325

  12. Nanocrystalline iron oxide aerogels as mesoporous magnetic architectures.

    PubMed

    Long, Jeffrey W; Logan, Michael S; Rhodes, Christopher P; Carpenter, Everett E; Stroud, Rhonda M; Rolison, Debra R

    2004-12-29

    We have developed crystalline nanoarchitectures of iron oxide that exhibit superparamagnetic behavior while still retaining the desirable bicontinuous pore-solid networks and monolithic nature of an aerogel. Iron oxide aerogels are initially produced in an X-ray-amorphous, high-surface-area form, by adapting recently established sol-gel methods using Fe(III) salts and epoxide-based proton scavengers. Controlled temperature/atmosphere treatments convert the as-prepared iron oxide aerogels into nanocrystalline forms with the inverse spinel structure. As a function of the bathing gas, treatment temperature, and treatment history, these nanocrystalline forms can be reversibly tuned to predominantly exhibit either Fe(3)O(4) (magnetite) or gamma-Fe(2)O(3) (maghemite) phases, as verified by electron microscopy, X-ray and electron diffraction, microprobe Raman spectroscopy, and magnetic analysis. Peak deconvolution of the Raman-active Fe-O bands yields valuable information on the local structure and vacancy content of the various aerogel forms, and facilitates the differentiation of Fe(3)O(4) and gamma-Fe(2)O(3) components, which are difficult to assign using only diffraction methods. These nanocrystalline, magnetic forms retain the inherent characteristics of aerogels, including high surface area (>140 m(2) g(-1)), through-connected porosity concentrated in the mesopore size range (2-50 nm), and nanoscale particle sizes (7-18 nm). On the basis of this synthetic and processing protocol, we produce multifunctional nanostructured materials with effective control of the pore-solid architecture, the nanocrystalline phase, and subsequent magnetic properties.

  13. Conquering the Dark Side: Colloidal Iron Oxide Nanoparticles

    PubMed Central

    Senpan, Angana; Caruthers, Shelton D.; Rhee, Ilsu; Mauro, Nicholas A.; Pan, Dipanjan; Hu, Grace; Scott, Michael J.; Fuhrhop, Ralph W.; Gaffney, Patrick J.; Wickline, Samuel A.; Lanza, Gregory M.

    2009-01-01

    Nanomedicine approaches to atherosclerotic disease will have significant impact on the practice and outcomes of cardiovascular medicine. Iron oxide nanoparticles have been extensively used for nontargeted and targeted imaging applications based upon highly sensitive T2* imaging properties, which typically result in negative contrast effects that can only be imaged 24 or more hours after systemic administration due to persistent blood pool interference. Although recent advances involving MR pulse sequences have converted these dark contrast voxels into bright ones, the marked delays in imaging from persistent magnetic background interference and prominent dipole blooming effects of the magnetic susceptibility remain barriers to overcome. We report a T1-weighted (T1w) theranostic colloidal iron oxide nanoparticle platform, CION, which is achieved by entrapping oleate-coated magnetite particles within a cross-linked phospholipid nanoemulsion. Contrary to expectations, this formulation decreased T2 effects thus allowing positive T1w contrast detection down to low nanomolar concentrations. CION, a vascular constrained nanoplatform administered in vivo permitted T1w molecular imaging 1 hour after treatment without blood pool interference, although some T2 shortening effects on blood, induced by the superparamagnetic particles persisted. Moreover, CION was shown to encapsulate antiangiogenic drugs, like fumagillin, and retained them under prolonged dissolution, suggesting significant theranostic functionality. Overall, CION is a platform technology, developed with generally recognized as safe components, that overcomes the temporal and spatial imaging challenges associated with current iron oxide nanoparticle T2 imaging agents, and which has theranostic potential in vascular diseases for detecting unstable ruptured plaque or treating atherosclerotic angiogenesis. PMID:19908850

  14. AN EFFICIENT AND ECOFRIENDLY OXIDATION OF ALKENES USING IRON NITRATE AND MOLECULAR OXYGEN

    EPA Science Inventory

    An environmentally friendly solventless oxidation of alkenes is accomplished efficiently using relatively benign iron nitrate as catalyst in the pressence of molecular oxygen under pressurized conditions.

  15. Tailoring the magnetic and pharmacokinetic properties of iron oxide magnetic particle imaging tracers

    PubMed Central

    Ferguson, Richard Mathew; Khandhar, Amit P; Arami, Hamed; Hua, Loc; Hovorka, Ondrej; Krishnan, Kannan M.

    2014-01-01

    Magnetic particle imaging (MPI) is an attractive new modality for imaging distributions of iron oxide nanoparticle tracers in vivo. With exceptional contrast, high sensitivity, and good spatial resolution, MPI shows promise for clinical imaging in angiography and oncology. Critically, MPI requires high-quality iron oxide nanoparticle tracers with tailored magnetic and surface properties to achieve its full potential. In this review, we discuss optimizing iron oxide nanoparticles’ physical, magnetic, and pharmacokinetic properties for MPI, highlighting results from our recent work in which we demonstrated tailored, biocompatible iron oxide nanoparticle tracers that provided two times better linear spatial resolution and five times better signal-to-noise ratio than Resovist. PMID:23787461

  16. Impact of Superparamagnetic Iron Oxide Nanoparticles on Vocal Fold Fibroblasts: Cell Behavior and Cellular Iron Kinetics.

    PubMed

    Pöttler, Marina; Fliedner, Anna; Schreiber, Eveline; Janko, Christina; Friedrich, Ralf Philipp; Bohr, Christopher; Döllinger, Michael; Alexiou, Christoph; Dürr, Stephan

    2017-12-01

    The voice is the most important instrument of communication. Tissue defects in the vocal fold (VF) area lead to serious reduction in quality of life, but thus far, no satisfactory VF implant exists. Therefore, we aim to establish a functional VF implant in a rabbit model by magnetic tissue engineering (MTE) using superparamagnetic iron oxide nanoparticles (SPION). Hence, iron quantification over time as well as cell behavior studies upon SPION treatment are of great importance. Rabbit VF fibroblasts (VFF) were treated with different concentrations of SPIONs (20, 40, and 80 μg/cm(2)), and iron content was examined for up to 40 days using microwave plasma-atom emission spectroscopy. The effects of SPION treatment on VFF (adhesion, spreading, and migration), which are important for the formation of 3D structures, were tested. Cellular SPION quantification revealed that there was no residual iron remaining in VFFs after 40 days. SPIONs had a dose-dependent effect on cell adhesion, with good tolerability observed up to 20 μg/cm(2). Migration and spreading were not significantly influenced by SPION treatment up to 80 μg/cm(2). To develop 3D structures, cell behavior should not be affected by SPION uptake. After 40 days, cells were free of iron as a result of metabolism or rarefication during cell division. Cell functions including adhesion, spreading, and migration were proven to be intact in a dose-dependent manner after SPION treatment, suggesting a safe usage of MTE for voice rehabilitation. Our results thus constitute a solid basis for a successful transfer of this technique into 3D constructs, in order to provide an individual and personalized human VF implant in the future.

  17. Enriched Iron(III)-Reducing Bacterial Communities are Shaped by Carbon Substrate and Iron Oxide Mineralogy.

    PubMed

    Lentini, Christopher J; Wankel, Scott D; Hansel, Colleen M

    2012-01-01

    Iron (Fe) oxides exist in a spectrum of structures in the environment, with ferrihydrite widely considered the most bioavailable phase. Yet, ferrihydrite is unstable and rapidly transforms to more crystalline Fe(III) oxides (e.g., goethite, hematite), which are poorly reduced by model dissimilatory Fe(III)-reducing microorganisms. This begs the question, what processes and microbial groups are responsible for reduction of crystalline Fe(III) oxides within sedimentary environments? Further, how do changes in Fe mineralogy shape oxide-hosted microbial populations? To address these questions, we conducted a large-scale cultivation effort using various Fe(III) oxides (ferrihydrite, goethite, hematite) and carbon substrates (glucose, lactate, acetate) along a dilution gradient to enrich for microbial populations capable of reducing Fe oxides spanning a wide range of crystallinities and reduction potentials. While carbon source was the most important variable shaping community composition within Fe(III)-reducing enrichments, both Fe oxide type and sediment dilution also had a substantial influence. For instance, with acetate as the carbon source, only ferrihydrite enrichments displayed a significant amount of Fe(III) reduction and the well-known dissimilatory metal reducer Geobacter sp. was the dominant organism enriched. In contrast, when glucose and lactate were provided, all three Fe oxides were reduced and reduction coincided with the presence of fermentative (e.g., Enterobacter spp.) and sulfate-reducing bacteria (e.g., Desulfovibrio spp.). Thus, changes in Fe oxide structure and resource availability may shift Fe(III)-reducing communities between dominantly metal-respiring to fermenting and/or sulfate-reducing organisms which are capable of reducing more recalcitrant Fe phases. These findings highlight the need for further targeted investigations into the composition and activity of speciation-directed metal-reducing populations within natural environments.

  18. Enriched Iron(III)-Reducing Bacterial Communities are Shaped by Carbon Substrate and Iron Oxide Mineralogy

    PubMed Central

    Lentini, Christopher J.; Wankel, Scott D.; Hansel, Colleen M.

    2012-01-01

    Iron (Fe) oxides exist in a spectrum of structures in the environment, with ferrihydrite widely considered the most bioavailable phase. Yet, ferrihydrite is unstable and rapidly transforms to more crystalline Fe(III) oxides (e.g., goethite, hematite), which are poorly reduced by model dissimilatory Fe(III)-reducing microorganisms. This begs the question, what processes and microbial groups are responsible for reduction of crystalline Fe(III) oxides within sedimentary environments? Further, how do changes in Fe mineralogy shape oxide-hosted microbial populations? To address these questions, we conducted a large-scale cultivation effort using various Fe(III) oxides (ferrihydrite, goethite, hematite) and carbon substrates (glucose, lactate, acetate) along a dilution gradient to enrich for microbial populations capable of reducing Fe oxides spanning a wide range of crystallinities and reduction potentials. While carbon source was the most important variable shaping community composition within Fe(III)-reducing enrichments, both Fe oxide type and sediment dilution also had a substantial influence. For instance, with acetate as the carbon source, only ferrihydrite enrichments displayed a significant amount of Fe(III) reduction and the well-known dissimilatory metal reducer Geobacter sp. was the dominant organism enriched. In contrast, when glucose and lactate were provided, all three Fe oxides were reduced and reduction coincided with the presence of fermentative (e.g., Enterobacter spp.) and sulfate-reducing bacteria (e.g., Desulfovibrio spp.). Thus, changes in Fe oxide structure and resource availability may shift Fe(III)-reducing communities between dominantly metal-respiring to fermenting and/or sulfate-reducing organisms which are capable of reducing more recalcitrant Fe phases. These findings highlight the need for further targeted investigations into the composition and activity of speciation-directed metal-reducing populations within natural environments. PMID

  19. Resistive switching in iron-oxide-filled carbon nanotubes.

    PubMed

    Cava, Carlos E; Persson, Clas; Zarbin, Aldo J G; Roman, Lucimara S

    2014-01-07

    Iron-oxide-filled carbon nanotubes exhibit an intriguing charge bipolarization behavior which allows the material to be applied in resistive memory devices. Raman analysis conducted with an electric field applied in situ shows the Kohn anomalies and a strong modification of the electronic properties related to the applied voltage intensity. In addition, the I(D)/I(G) ratio indicated the reversibility of this process. The electrical characterization indicated an electronic transport governed by two main kinds of charge hopping, one between the filling and the nanotube and the other between the nanotube shells.

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

    SciTech Connect

    Raul, Prasanta Kumar; Devi, Rashmi Rekha; Umlong, Iohborlang M.; Thakur, Ashim Jyoti; Banerjee, Saumen; Veer, Vijay

    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

  1. Catalytic effect of free iron ions and heme-iron on chromophore oxidation of a polyene antibiotic amphotericin B

    NASA Astrophysics Data System (ADS)

    Czernel, Grzegorz; Typek, Rafał; Klimek, Katarzyna; Czuryło, Aleksandra; Dawidowicz, Andrzej L.; Gagoś, Mariusz

    2016-05-01

    Owing to the presence of a chromophore in the amphotericin B (AmB) structure, the molecule can undergo the oxidation process. In this research, AmB chromophore oxidation was catalysed by iron ions (iron(III) chloride (FeCl3), pH 2.5) and by heme-iron (methemoglobin (HbFe(III)), and hemin (heme-Fe(III)) at pH 7.0). Additionally, we compared oxidation processes induced by the aforementioned oxidizing agents with autoxidation by dioxygen (O2) naturally occurring in a sample. The effects of the interaction of the oxidizing agents with AmB were analysed using molecular spectroscopies (electronic absorption (UV-Vis), fluorescence) and LC-MS. The use of a 1,10-phenanthroline (phen) chelator facilitated unambiguous determination of the oxidative effect of free iron(III) ions (FeIII) in an acidic solution on the AmB molecules. Also, the changes in the spectra of fluorescence emission centred at ∼470 nm indicate iron-catalysed processes of AmB chromophore oxidation. Unexpectedly, we found a similar spectroscopic effect for AmB induced by methemoglobin and hemin at pH 7.0. Methemoglobin and hemin at a concentration of 8 × 10-7 M (physiological) significantly increases the rate of the processes of AmB chromophore oxidation relative to the process of autoxidation.

  2. Role of humic substances in promoting autotrophic growth in nitrate-dependent iron-oxidizing bacteria.

    PubMed

    Kanaparthi, Dheeraj; Conrad, Ralf

    2015-05-01

    Nitrate-dependent iron oxidation was discovered in 1996 and has been reported from various environments ever since. To date, despite the widespread nature of this process, all attempts to cultivate chemolithoautotrophic nitrate-dependent iron oxidizers have been unsuccessful. The present study was focused on understanding the influence of natural chelating agents of iron, like humic substances, on the culturability, activity, and enumeration, of these microorganisms. Pure culture studies conducted with Thiobacillus denitrificans showed a constant increase in cell mass with a corresponding nitrate-dependent iron oxidation activity only when Fe(II) was provided together with humic substances, compared to no growth in control incubations without humic substances. The presence of a relatively strong chelating agent, such as EDTA, inhibited the growth of Thiobacillus denitrificans. It was concluded that complex formation between humic substances and iron was required for chemolithoautotrophic nitrate-dependent iron oxidation. Most probable number enumerations showed that numbers of chemolithoautotrophic nitrate-dependent iron-oxidizing bacteria were one to three orders of magnitude higher in the presence of humic substances compared to media without. Similar results were obtained when potential nitrate-dependent iron oxidation activity was determined in soil samples. In summary, this study showed that humic substances significantly enhanced the growth and activity of autotrophic nitrate-dependent iron-oxidizing microorganisms, probably by chelation of iron. Copyright © 2015 Elsevier GmbH. All rights reserved.

  3. Evidence for equilibrium iron isotope fractionation by nitrate-reducing iron(II)-oxidizing bacteria

    PubMed Central

    Kappler, A.; Johnson, C.M.; Crosby, H.A.; Beard, B.L.; Newman, D.K.

    2010-01-01

    Iron isotope fractionations produced during chemical and biological Fe(II) oxidation are sensitive to the proportions and nature of dissolved and solid-phase Fe species present, as well as the extent of isotopic exchange between precipitates and aqueous Fe. Iron isotopes therefore potentially constrain the mechanisms and pathways of Fe redox transformations in modern and ancient environments. In the present study, we followed in batch experiments Fe isotope fractionations between Fe(II)aq and Fe(III) oxide/hydroxide precipitates produced by the Fe(III) mineral encrusting, nitrate-reducing, Fe(II)-oxidizing Acidovorax sp. strain BoFeN1. Isotopic fractionation in 56Fe/54Fe approached that expected for equilibrium conditions, assuming an equilibrium Δ56FeFe(OH)3 – Fe(II)aq fractionation factor of +3.0 ‰. Previous studies have shown that Fe(II) oxidation by this Acidovorax strain occurs in the periplasm, and we propose that Fe isotope equilibrium is maintained through redox cycling via coupled electron and atom exchange between Fe(II)aq and Fe(III) precipitates in the contained environment of the periplasm. In addition to the apparent equilibrium isotopic fractionation, these experiments also record the kinetic effects of initial rapid oxidation, and possible phase transformations of the Fe(III) precipitates. Attainment of Fe isotope equilibrium between Fe(III) oxide/hydroxide precipitates and Fe(II)aq by neutrophilic, Fe(II)-oxidizing bacteria or through abiologic Fe(II)aq oxidation is generally not expected or observed, because the poor solubility of their metabolic product, i.e. Fe(III), usually leads to rapid precipitation of Fe(III) minerals, and hence expression of a kinetic fractionation upon precipitation; in the absence of redox cycling between Fe(II)aq and precipitate, kinetic isotope fractionations are likely to be retained. These results highlight the distinct Fe isotope fractionations that are produced by different pathways of biological and

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

    USGS Publications Warehouse

    Hem, J.D.

    1977-01-01

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

  5. Morphology and phase control of iron oxide polymorph nanoparticles

    NASA Astrophysics Data System (ADS)

    Cui, Hongtao; Wang, Li; Shi, Min; Li, Yanhong

    2017-04-01

    In this work, lepidocrocite (γ-FeOOH) nanobundles were prepared by a facile NH4F assisted epoxide precipitation route. The reactions between epoxide and [Fe(H2O)6]2+ promoted the hydrolysis and condensation of [Fe(H2O)6]2+, resulting in the formation of iron oxyhydroxide. After calcination of γ-FeOOH nanobundles at 400 °C, the produced α-Fe2O3 still kept the bundle morphology. Due to the unique chemistry of epoxide, the morphology and phase of iron oxide polymorph nanoparticles (goethite, akaganeite, lepidocrocite, magnetite) were well-controlled through controlling reaction conditions such as Fe2+ concentration, NH4F additive and reaction temperature. It is particularly interesting that NH4F working as phase controlling agent is able to control the phase development of iron oxyhydroxides. This phase control effect of NH4F is attributed to the promoted reaction rate of epoxide originating from the higher electronegativity of fluoride ions than chloride ions. Based on the results in this work and our other preliminary works, it is considered that this route can be used as a general strategy for controlling the morphology and phase of transition element compounds.

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

    NASA Astrophysics Data System (ADS)

    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. Engineered Iron/Iron Oxide Functionalized Membranes for Selenium and Other Toxic Metal Removal from Power Plant Scrubber Water.

    PubMed

    Gui, Minghui; Papp, Joseph K; Colburn, Andrew S; Meeks, Noah D; Weaver, Benjamin; Wilf, Ilan; Bhattacharyya, Dibakar

    2015-08-15

    The remediation of toxic metals from water with high concentrations of salt has been an emerging area for membrane separation. Cost-effective nanomaterials such as iron and iron oxide nanoparticles have been widely used in reductive and oxidative degradation of toxic organics. Similar procedures can be used for redox transformations of metal species (e.g. metal oxyanions to elemental metal), and/or adsorption of species on iron oxide surface. In this study, iron-functionalized membranes were developed for reduction and adsorption of selenium from coal-fired power plant scrubber water. Iron-functionalized membranes have advantages over iron suspension as the membrane prevents particle aggregation and dissolution. Both lab-scale and full-scale membranes were prepared first by coating polyvinylidene fluoride (PVDF) membranes with polyacrylic acid (PAA), followed by ion exchange of ferrous ions and subsequent reduction to zero-valent iron nanoparticles. Water permeability of membrane decreased as the percent PAA functionalization increased, and the highest ion exchange capacity (IEC) was obtained at 20% PAA with highly pH responsive pores. Although high concentrations of sulfate and chloride in scrubber water decreased the reaction rate of selenium reduction, this was shown to be overcome by integration of nanofiltration (NF) and iron-functionalized membranes, and selenium concentration below 10 μg/L was achieved.

  8. Intracellular degradation of functionalized carbon nanotube/iron oxide hybrids is modulated by iron via Nrf2 pathway

    PubMed Central

    Elgrabli, Dan; Dachraoui, Walid; Marmier, Hélène de; Ménard-Moyon, Cécilia; Bégin, Dominique; Bégin-Colin, Sylvie; Bianco, Alberto; Alloyeau, Damien; Gazeau, Florence

    2017-01-01

    The in vivo fate and biodegradability of carbon nanotubes is still a matter of debate despite tremendous applications. In this paper we describe a molecular pathway by which macrophages degrade functionalized multi-walled carbon nanotubes (CNTs) designed for biomedical applications and containing, or not, iron oxide nanoparticles in their inner cavity. Electron microscopy and Raman spectroscopy show that intracellularly-induced structural damages appear more rapidly for iron-free CNTs in comparison to iron-loaded ones, suggesting a role of iron in the degradation mechanism. By comparing the molecular responses of macrophages derived from THP1 monocytes to both types of CNTs, we highlight a molecular mechanism regulated by Nrf2/Bach1 signaling pathways to induce CNT degradation via NOX2 complex activation and O2•−, H2O2 and OH• production. CNT exposure activates an oxidative stress-dependent production of iron via Nrf2 nuclear translocation, Ferritin H and Heme oxygenase 1 translation. Conversely, Bach1 was translocated to the nucleus of cells exposed to iron-loaded CNTs to recycle embedded iron. Our results provide new information on the role of oxidative stress, iron metabolism and Nrf2-mediated host defence for regulating CNT fate in macrophages. PMID:28120861

  9. A 'degradable' poly(vinyl alcohol) iron oxide nanoparticle hydrogel.

    PubMed

    Bannerman, A Dawn; Li, Xinyi; Wan, Wankei

    2017-08-01

    Polymeric materials that contain magnetic nanoparticles are extremely useful in many applications including as multifunctional drug carriers, imaging contrast agents, or scaffold material. There is a need for biomaterials with appropriate chemical, mechanical, and magnetic properties that also have the ability to degrade or dissolve over time so they can be eliminated from the body following use. In this work, we explore the use of iron oxide nanoparticle (IONP) formation in poly(vinyl alcohol) (PVA) as a crosslinking method in conjunction with physical crosslinking achieved using low temperature thermal cycling (LTTC). PVA-IONP hydrogels were fabricated and characterized. IONPs contribute to the crosslinking of the PVA-IONP material, and their subsequent removal reduces crosslinking, and therefore stability, of the material, allowing dissolution to occur. Dissolution studies were performed on PVA-IONP hydrogels and dissolution was compared for films in solutions of varying pH, in the presence of iron chelating agents, and in simulated physiological and tumor conditions in cell culture media. Iron release, mass loss, and mechanical testing data was collected. This work demonstrates the ability of this biomaterial to 'degrade' over time, which may be very advantageous for applications such as drug delivery. This importance of this work extends to other areas such as the use of stimuli-responsive hydrogels. This manuscript explores the stability of an iron oxide nanoparticle (IONP)-containing, physically crosslinked poly(vinyl alcohol) (PVA) hydrogel. The PVA-IONP hydrogel's stability is imparted through crosslinks created through a low temperature thermal cycling process and through the IONPs. Subsequent IONP removal reduces crosslinks so material dissolution can occur, resulting in a 'degradable' and multifunctional biomaterial. PVA-IONP films were fabricated, characterized and evaluated in terms of dissolution in solutions of varying pH and in the presence of

  10. Severe Respiratory Distress in a Child with Pulmonary Idiopathic Hemosiderosis Initially Presenting with Iron-Deficiency Anemia

    PubMed Central

    Potalivo, A.; Finessi, L.; Facondini, F.; Lupo, A.; Andreoni, C.; Giuliani, G.; Cavicchi, C.

    2015-01-01

    Idiopathic pulmonary hemosiderosis (IPH) is a rare cause of alveolar hemorrhage in children but should be considered in children with anemia of unknown origin who develop respiratory complications. It is commonly characterized by the triad of recurrent hemoptysis, diffuse parenchymal infiltrates, and iron-deficiency anemia. Pathogenesis is unclear and diagnosis may be difficult along with a variable clinical course. A 6-year-old boy was admitted to the hospital with a severe iron-deficiency anemia, but he later developed severe acute respiratory failure and hemoptysis requiring intubation and mechanical ventilation. The suspicion of IPH led to the use of immunosuppressive therapy with high dose of corticosteroids with rapid improvement in clinical condition and discharge from hospital. PMID:26634166

  11. Enhancing the Performance of the Rechargeable Iron Electrode in Alkaline Batteries with Bismuth Oxide and Iron Sulfide Additives

    SciTech Connect

    Manohar, AK; Yang, CG; Malkhandi, S; Prakash, GKS; Narayanan, SR

    2013-09-07

    Iron-based alkaline rechargeable batteries have the potential of meeting the needs of large-scale electrical energy storage because of their low-cost, robustness and eco-friendliness. However, the widespread commercial deployment of iron-based batteries has been limited by the low charging efficiency and the poor discharge rate capability of the iron electrode. In this study, we have demonstrated iron electrodes containing bismuth oxide and iron sulfide with a charging efficiency of 92% and capable of being discharged at the 3C rate. Such a high value of charging efficiency combined with the ability to discharge at high rates is being reported for the first time. The bismuth oxide additive led to the in situ formation of elemental bismuth and a consequent increase in the overpotential for the hydrogen evolution reaction leading to an increase in the charging efficiency. We observed that the sulfide ions added to the electrolyte and iron sulfide added to the electrode mitigated-electrode passivation and allowed for continuous discharge at high rates. At the 3C discharge rate, a utilization of 0.2 Ah/g was achieved. The performance level of the rechargeable iron electrode demonstrated here is attractive for designing economically-viable large-scale energy storage systems based on alkaline nickel-iron and iron-air batteries. (C) 2013 The Electrochemical Society. All rights reserved.

  12. Effects of iron oxide mineralogy on methanogenesis transpiring in soils and sediments

    NASA Astrophysics Data System (ADS)

    Gadol, H. J.; Kocar, B. D.

    2016-12-01

    Methane is an important greenhouse gas, possessing a global warming potential 30 times greater than carbon dioxide over a 100 year period. Soils and sediments, particularly within wetland environments, are dominant sources of methane to the Earth's atmosphere; however, the extent and magnitude of soil-sediment methane emissions are difficult to constrain owing to complex biogeochemical-physical controls on methanogenic activity. Methanogenesis may be inhibited in the presence of terminal electron acceptors that provide a greater free energy yield, including sulfate and iron(III)-bearing solids. Of these, Fe(III) solids (dominantly iron (hydr)oxides such as ferrihydrite, goethite, and hematite), possess a range of thermodynamic properties that impart different inhibitory effects on methanogenesis. Also, a recently proposed mechanism that predicts coupled iron reduction-methanogenesis—direct interspecies electron transfer (DIET)—may further convolute predictions of methane evolution in systems containing iron hydr(oxides). It is possible that, under energetically favorable conditions, iron reducers contribute an electron to a (semi)conductive iron oxide; this electron can then be conducted through the mineral and subsequently used by another microbe to produce methane. This research aims to explore the effect of iron chemistry and mineralogy on electron transfer between iron-reducing microbes and methanogens. A number of iron oxide minerals with varying crystallinities and conductivities were inoculated with wetland sediment. Iron and methane were monitored throughout the course of the experiments. Iron in solution was measured using inductively coupled plasma - optical emission spectroscopy (ICP-OES), while HCl-extractable iron was measured using spectrophotometric methods. Headspace methane was measured using a residual gas analyzer (RGA). According to thermodynamic predictions, enhanced methanogenic activity is observed in the presence of crystalline iron

  13. Iron and oxygen isotope fractionation during iron UV photo-oxidation: Implications for early Earth and Mars

    NASA Astrophysics Data System (ADS)

    Nie, Nicole X.; Dauphas, Nicolas; Greenwood, Richard C.

    2017-01-01

    Banded iron formations (BIFs) contain appreciable amounts of ferric iron (Fe3+). The mechanism by which ferrous iron (Fe2+) was oxidized into Fe3+ in an atmosphere that was globally anoxic is highly debated. Of the three scenarios that have been proposed to explain BIF formation, photo-oxidation by UV photons is the only one that does not involve life (the other two are oxidation by O2 produced by photosynthesis, and anoxygenic photosynthesis whereby Fe2+ is directly used as electron donor in place of water). We experimentally investigated iron and oxygen isotope fractionation imparted by iron photo-oxidation at a pH of 7.3. The iron isotope fractionation between precipitated Fe3+-bearing lepidocrocite and dissolved Fe2+ follows a Rayleigh distillation with an instantaneous 56Fe/54Fe fractionation factor of + 1.2 ‰. Such enrichment in the heavy isotopes of iron is consistent with the values measured in BIFs. We also investigated the nature of the mass-fractionation law that governs iron isotope fractionation in the photo-oxidation experiments (i.e., the slope of the δ56Fe-δ57Fe relationship). The experimental run products follow a mass-dependent law corresponding to the high-T equilibrium limit. The fact that a ∼3.8 Gyr old BIF sample (IF-G) from Isua (Greenland) falls on the same fractionation line confirms that iron photo-oxidation in the surface layers of the oceans was a viable pathway to BIF formation in the Archean, when the atmosphere was largely transparent to UV photons. Our experiments allow us to estimate the quantum yield of the photo-oxidation process (∼0.07 iron atom oxidized per photon absorbed). This yield is used to model iron oxidation on early Mars. As the photo-oxidation proceeds, the aqueous medium becomes more acidic, which slows down the reaction by changing the speciation of iron to species that are less efficient at absorbing UV-photons. Iron photo-oxidation in centimeter to meter-deep water ponds would take months to years to

  14. Morphology of biogenic iron oxides records microbial physiology and environmental conditions: toward interpreting iron microfossils.

    PubMed

    Krepski, S T; Emerson, D; Hredzak-Showalter, P L; Luther, G W; Chan, C S

    2013-09-01

    Despite the abundance of Fe and its significance in Earth history, there are no established robust biosignatures for Fe(II)-oxidizing micro-organisms. This limits our ability to piece together the history of Fe biogeochemical cycling and, in particular, to determine whether Fe(II)-oxidizers played a role in depositing ancient iron formations. A promising candidate for Fe(II)-oxidizer biosignatures is the distinctive morphology and texture of extracellular Fe(III)-oxyhydroxide stalks produced by mat-forming microaerophilic Fe(II)-oxidizing micro-organisms. To establish the stalk morphology as a biosignature, morphologic parameters must be quantified and linked to the microaerophilic Fe(II)-oxidizing metabolism and environmental conditions. Toward this end, we studied an extant model organism, the marine stalk-forming Fe(II)-oxidizing bacterium, Mariprofundus ferrooxydans PV-1. We grew cultures in flat glass microslide chambers, with FeS substrate, creating opposing oxygen/Fe(II) concentration gradients. We used solid-state voltammetric microelectrodes to measure chemical gradients in situ while using light microscopy to image microbial growth, motility, and mineral formation. In low-oxygen (2.7-28 μm) zones of redox gradients, the bacteria converge into a narrow (100 μm-1 mm) growth band. As cells oxidize Fe(II), they deposit Fe(III)-oxyhydroxide stalks in this band; the stalks orient directionally, elongating toward higher oxygen concentrations. M. ferrooxydans stalks display a narrow range of widths and uniquely biogenic branching patterns, which result from cell division. Together with filament composition, these features (width, branching, and directional orientation) form a physical record unique to microaerophilic Fe(II)-oxidizer physiology; therefore, stalk morphology is a biosignature, as well as an indicator of local oxygen concentration at the time of formation. Observations of filamentous Fe(III)-oxyhydroxide microfossils from a ~170 Ma marine Fe

  15. Iron and manganese oxide mineralization in the Pacific

    USGS Publications Warehouse

    Hein, J.R.; Koschinsky, A.; Halbach, P.; Manheim, F. T.; Bau, M.; Kang, J.-K.; 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. Iron and manganese deposits occur in five forms: nodules, crusts, cements, mounds and sediment-hosted stratabound layers. Seafloor oxides show a wide range of compositions from nearly pure iron to nearly pure manganese end members. Fe/Mn ratios vary from about 24 000 (up to 58% elemental Fe) for hydrothermal seamount ironstones to about 0.001 (up to 52% Mn) for hydrothermal stratabound manganese oxides from active volcanic arcs. Hydrogenetic Fe-Mn crusts that occur on most seamounts in the ocean basins have a mean Fe/Mn ratio of 0.7 for open-ocean seamount crusts and 1.2 for continental margin seamount crusts. Fe-Mn nodules of potential economic interest from the Clarion-Clipperton Zone have a mean Fe/Mn ratio of 0.3, whereas the mean ratio for nodules from elsewhere in the Pacific is about 0.7. Crusts are enriched in Co, Ni and Pt and nodules in Cu and Ni, and both have significant concentrations of Pb, Zn, Ba, Mo, V and other elements. In contrast, hydrothermal deposits commonly contain only minor trace metal contents, although there are many exceptions, for example, with Ni contents up to 0.66%, Cr to 1.2%, and Zn to 1.4%. Chondrite-normalized REE patterns generally show a positive Ce anomaly and abundant ΣREEs for hydrogenetic and mixed hydrogenetic-diagenetic deposits, whereas the Ce anomaly is negative for hydrothermal deposits and ΣREE contents are low. However, the Ce anomaly in crusts may vary from strongly positive in East Pacific crusts to slightly negative in West Pacific crusts, which may reflect

  16. Iron release and membrane damage in erythrocytes exposed to oxidizing agents, phenylhydrazine, divicine and isouramil.

    PubMed Central

    Ferrali, M; Signorini, C; Ciccoli, L; Comporti, M

    1992-01-01

    Mouse erythrocytes were incubated with oxidizing agents, phenylhydrazine, divicine and isouramil. With all the oxidants a rapid release of iron in a desferrioxamine (DFO)-chelatable form was seen and it was accompanied by methaemoglobin formation. If the erythrocytes were depleted of GSH by a short preincubation with diethyl maleate, the release of iron was accompanied by lipid peroxidation and, subsequently, haemolysis. GSH depletion by itself did not induce iron release, methaemoglobin formation, lipid peroxidation or haemolysis. Rather, the fate of the cell in which iron is released depended on the intracellular availability of GSH. In addition, iron release was higher in depleted cells than in native ones, suggesting a role for GSH in preventing iron release when oxidative stress is imposed by the oxidants. Iron release preceded lipid peroxidation. The latter was prevented when the erythrocytes were preloaded with DFO in such a way (preincubation with 10 mM-DFO) that the intracellular concentration was equivalent to that of the released iron, but not when the intracellular DFO was lower (preincubation with 0.1 mM-DFO). Extracellular DFO did not affect lipid peroxidation and haemolysis, suggesting again that the observed events occur intracellularly (intracellular chelation of released iron). The relevance of iron release from iron complexes in the mechanisms of cellular damage induced by oxidative stress is discussed. PMID:1637315

  17. Tuning the structure and habit of iron oxide mesocrystals

    DOE PAGES

    Wetterskog, Erik; Klapper, Alice; Disch, Sabrina; ...

    2016-07-11

    A precise control over the meso- and microstructure of ordered and aligned nanoparticle assemblies, i.e., mesocrystals, is essential in the quest for exploiting the collective material properties for potential applications. In this work, we produced evaporation-induced self-assembled mesocrystals with different mesostructures and crystal habits based on iron oxide nanocubes by varying the nanocube size and shape and by applying magnetic fields. A full 3D characterization of the mesocrystals was performed using image analysis, high-resolution scanning electron microscopy and Grazing Incidence Small Angle X-ray Scattering (GISAXS). This enabled the structural determination of e.g. multi-domain mesocrystals with complex crystal habits and themore » quantification of interparticle distances with sub-nm precision. Mesocrystals of small nanocubes (l = 8.6 12.6 nm) are isostructural with a body centred tetragonal (bct ) lattice whereas assemblies of the largest nanocubes in this study (l = 13.6 nm) additionally form a simple cubic (sc) lattice. The mesocrystal habit can be tuned from a square, hexagonal to star-like and pillar shapes depending on the particle size and shape and the strength of the applied magnetic field. Finally, we outline a qualitative phase diagram of the evaporation-induced self-assembled superparamagnetic iron oxide nanocube mesocrystals based on nanocube edge length and magnetic field strength.« less

  18. Noble Metal-Iron Oxide Hybrid Nanomaterials: Emerging Applications.

    PubMed

    Leung, Ken Cham-Fai; Xuan, Shouhu

    2016-02-01

    This account provides an overview of current research activities that focus on the synthesis and applications of nanomaterials from noble metal (e.g., Au, Ag, Pd) and iron oxide (Fe3O4) hybrids. An introduction to the synthetic strategies that have been developed for generating M-Fe3O4 nanomaterials with different novel structures is presented. Surface functionalization and bioconjugation of these hybrid nanoparticles and nanocomposites are also reviewed. The utilization of the advantageous properties of both noble metals and iron oxide for a variety of applications, such as theranostics, gene delivery, biosensing, cell sorting, bioseparation, and catalysis, is discussed and highlighted. Finally, future trends and perspectives of these sophisticated nanocomposites are outlined. The fundamental requirements underpinning the effective preparation of M-Fex Oy hybrid nanomaterials shed light on the future development of heterogeneous catalysts, nanotheranostics, nanomedicines, and other chemical technologies. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Cerebral Blood Volume MRI with Intravascular Superparamagentic Iron Oxide Nanoparticles

    PubMed Central

    Kim, Seong-Gi; Harel, Noam; Jin, Tao; Kim, Tae; Lee, Phil; Zhao, Fuqiang

    2013-01-01

    Cerebral blood volume (CBV) is a crucial physiological indicator of tissue viability and vascular reactivity. Thus, non-invasive CBV mapping has been of great interest. For this, ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) including monocrystalline iron oxide nanoparticles (MION) can be used as long half-life, intravascular susceptibility agents of CBV MRI measurements. Also, CBV-weighted fMRI with USPIO provides enhanced sensitivity, reduced large vessel contribution, and improved spatial specificity compared to conventional blood oxygenation-level dependent (BOLD) fMRI, and measures a single physiological parameter that is easily interpretable. We review physiochemical and magnetic properties as well as pharmacokinetics of USPIO in brief. We then extensively discuss quantifications of baseline CBV, vessel size index, and functional CBV change. We also provide reviews of dose-dependent sensitivity, vascular filter function, specificity, characteristics, and impulse response function of CBV fMRI. Examples of CBV fMRI specificity at the laminar and columnar resolution are provided. Finally, we briefly review application of CBV measurements to functional and pharmacological studies in animals. Overall, the use of USPIO can determine baseline CBV and its changes induced by functional activity and pharmacological interventions. PMID:23208650

  20. Evaluation of Nanodispersion of Iron Oxides Using Various Polymers

    PubMed Central

    Tanaka, Y.; Ueyama, H.; Ogata, M.; Daikoku, T.; Morimoto, M.; Kitagawa, A.; Imajo, Y.; Tahara, T.; Inkyo, M.; Yamaguchi, N.; Nagata, S.

    2014-01-01

    In order to create Fe2O3 and Fe2O3·H2O nanoparticles, various polymers were used as dispersing agents, and the resulting effects on the dispersibility and nanoparticulation of the iron oxides were evaluated. It was revealed that not only the solution viscosity but also the molecular length of the polymers and the surface tension of the particles affected the dispersibility of Fe2O3 and Fe2O3·H2O particles. Using the dispersing agents 7.5% hydroxypropylcellulose-SSL, 6.0% Pharmacoat 603, 5.0% and 6.5% Pharmacoat 904 and 7.0% Metolose SM-4, Fe2O3 nanoparticles were successfully fabricated by wet milling using Ultra Apex Mill. Fe2O3·H2O nanoparticles could also be produced using 5.0% hydroxypropylcellulose-SSL and 4.0 and 7.0% Pharmacoat 904. The index for dispersibility developed in this study appears to be an effective indicator of success in fabricating nanoparticles of iron oxides by wet milling using Ultra Apex Mill. PMID:24799739

  1. Tuning the structure and habit of iron oxide mesocrystals

    SciTech Connect

    Wetterskog, Erik; Klapper, Alice; Disch, Sabrina; Josten, Elisabeth; Hermann, Raphaël P.; Rücker, Ulrich; Brückel, Thomas; Bergström, Lennart; Salazar-Alvarez, German

    2016-07-11

    A precise control over the meso- and microstructure of ordered and aligned nanoparticle assemblies, i.e., mesocrystals, is essential in the quest for exploiting the collective material properties for potential applications. In this work, we produced evaporation-induced self-assembled mesocrystals with different mesostructures and crystal habits based on iron oxide nanocubes by varying the nanocube size and shape and by applying magnetic fields. A full 3D characterization of the mesocrystals was performed using image analysis, high-resolution scanning electron microscopy and Grazing Incidence Small Angle X-ray Scattering (GISAXS). This enabled the structural determination of e.g. multi-domain mesocrystals with complex crystal habits and the quantification of interparticle distances with sub-nm precision. Mesocrystals of small nanocubes (l = 8.6 12.6 nm) are isostructural with a body centred tetragonal (bct ) lattice whereas assemblies of the largest nanocubes in this study (l = 13.6 nm) additionally form a simple cubic (sc) lattice. The mesocrystal habit can be tuned from a square, hexagonal to star-like and pillar shapes depending on the particle size and shape and the strength of the applied magnetic field. Finally, we outline a qualitative phase diagram of the evaporation-induced self-assembled superparamagnetic iron oxide nanocube mesocrystals based on nanocube edge length and magnetic field strength.

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

    PubMed

    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.

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

    PubMed

    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.

  4. Nickel aluminides and nickel-iron aluminides for use in oxidizing environments

    DOEpatents

    Liu, Chain T.

    1988-03-15

    Nickel aluminides and nickel-iron aluminides treated with hafnium or zirconium, boron and cerium to which have been added chromium to significantly improve high temperature ductility, creep resistance and oxidation properties in oxidizing environments.

  5. Effect of radiation energy and intracellular iron dose on iron oxide nanoparticle enhancement of radiation cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mazur, Courtney M.; Strawbridge, Rendall R.; Thompson, Ella S.; Petryk, Alicia A.; Gladstone, David J.; Hoopes, P. Jack

    2015-03-01

    Iron oxide nanoparticles (IONPs) are one of several high-Z materials currently being investigated for their ability to enhance the cytotoxic effects of therapeutic ionizing radiation. Studies with iron oxide, silver, gold, and hafnium oxide suggest radiation dose, radiation energy, cell type, and the type and level of metallic nanoparticle are all critical factors in achieving radiation enhancement in tumor cells. Using a single 4 Gy radiation dose, we compared the level of tumor cell cytotoxicity at two different intracellular iron concentrations and two different radiation energies in vitro. IONPs were added to cell culture media at concentrations of 0.25 mg Fe/mL and 1.0 mg Fe/mL and incubated with murine breast adenocarcinoma (MTG-B) cells for 72 hours. Extracellular iron was then removed and cells were irradiated at either 662 keV or 10 MV. At the 0.25 mg Fe/mL dose (4 pg Fe/cell), radiation energy did not affect the level of cytotoxicity. However with 1.0 mg Fe/mL (9 pg Fe/cell), the higher 10 MV radiation energy resulted in 50% greater cytotoxicity as compared to cells without IONPs irradiated at this energy. These results suggest IONPs may be able to significantly enhance the cytotoxic effects of radiation and improve therapeutic ratio if they can be selectively associated with cancer cells and/or tumors. Ongoing in vivo studies of IONP radiation enhancement in a murine tumor model are too immature to draw conclusions from at this time, however preliminary data suggests similar effectiveness of IONP radiation enhancement at 6 MV and 18 MV energy levels. In addition to the IONP-based radiation enhancement demonstrated here, the use of tumor-localized IONP with an externally delivered, non-toxic alternating magnetic field affords the opportunity to selectively heat and kill tumor cells. Combining IONP-based radiation sensitization and heat-based cytotoxicity provides a unique and potentially highly effective opportunity for therapeutic ratio enhancement.

  6. Mapping the Iron Oxidation State in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Martin, A. M.; Treimann, A. H.; Righter, K.

    2017-01-01

    Several types of Martian igneous meteorites have been identified: clinopyroxenites (nakhlites), basaltic shergottites, peridotitic shergottites, dunites (chassignites) and orthopyroxenites [1,2]. In order to constrain the heterogeneity of the Martian mantle and crust, and their evolution through time, numerous studies have been performed on the iron oxidation state of these meteorites [3,4,5,6,7,8,9]. The calculated fO2 values all lie within the FMQ-5 to FMQ+0.5 range (FMQ representing the Fayalite = Magnetite + Quartz buffer); however, discrepancies appear between the various studies, which are either attributed to the choice of the minerals/melts used, or to the precision of the analytical/calculation method. The redox record in volcanic samples is primarily related to the oxidation state in the mantle source(s). However, it is also influenced by several deep processes: melting, crystallization, magma mixing [10], assimilation and degassing [11]. In addition, the oxidation state in Martian meteorites is potentially affected by several surface processes: assimilation of sediment/ crust during lava flowing at Mars' surface, low temperature micro-crystallization [10], weathering at the surface of Mars and low temperature reequilibration, impact processes (i.e. high pressure phase transitions, mechanical mixing, shock degassing and melting), space weathering, and weathering on Earth (at atmospheric conditions different from Mars). Decoding the redox record of Martian meteorites, therefore, requires large-scale quantitative analysis methods, as well as a perfect understanding of oxidation processes.

  7. Atomistic simulations of uranium incorporation into iron (hydr)oxides.

    PubMed

    Kerisit, Sebastien; Felmy, Andrew R; Ilton, Eugene S

    2011-04-01

    Atomistic simulations were carried out to characterize the coordination environments of U incorporated in three Fe-(hydr)oxide minerals: goethite, magnetite, and hematite. The simulations provided information on U-O and U-Fe distances, coordination numbers, and lattice distortion for U incorporated in different sites (e.g., unoccupied versus occupied sites, octahedral versus tetrahedral) as a function of the oxidation state of U and charge compensation mechanisms (i.e., deprotonation, vacancy formation, or reduction of Fe(III) to Fe(II)). For goethite, deprotonation of first shell hydroxyls enables substitution of U for Fe(III) with a minimal amount of lattice distortion, whereas substitution in unoccupied octahedral sites induced appreciable distortion to 7-fold coordination regardless of U oxidation states and charge compensation mechanisms. Importantly, U-Fe distances of ∼3.6 Å were associated with structural incorporation of U and cannot be considered diagnostic of simple adsorption to goethite surfaces. For magnetite, the octahedral site accommodates U(V) or U(VI) with little lattice distortion. U substituted for Fe(III) in hematite maintained octahedral coordination in most cases. In general, comparison of the simulations with available experimental data provides further evidence for the structural incorporation of U in iron (hydr)oxide minerals.

  8. Atomistic Simulations of Uranium Incorporation into Iron (Hydr)Oxides

    SciTech Connect

    Kerisit, Sebastien N.; Felmy, Andrew R.; Ilton, Eugene S.

    2011-04-29

    Atomistic simulations were carried out to characterize the coordination environments of U incorporated in three Fe-(hydr)oxide minerals: goethite, magnetite, and hematite. The simulations provided information on U-O and U-Fe distances, coordination numbers, and lattice distortion for U incorporated in different sites (e.g., unoccupied versus occupied sites, octahedral versus tetrahedral) as a function of the oxidation state of U and charge compensation mechanisms (i.e., deprotonation, vacancy formation, or reduction of Fe(III) to Fe(II)). For goethite, deprotonation of first shell hydroxyls enables substitution of U for Fe(III) with a minimal amount of lattice distortion, whereas substitution in unoccupied octahedral sites induced appreciable distortion to 7-fold coordination regardless of U oxidation states and charge compensation mechanisms. Importantly, U-Fe distances of ~3.6 Å were associated with structural incorporation of U and cannot be considered diagnostic of simple adsorption to goethite surfaces. For magnetite, the octahedral site accommodates U(V) or U(VI) with little lattice distortion. U substituted for Fe(III) in hematite maintained octahedral coordination in most cases. In general, comparison of the simulations with available experimental data provides further evidence for the structural incorporation of U in iron (hydr)oxide minerals.

  9. Effect of dietary iron and copper on performance and oxidative stability in broiler leg meat.

    PubMed

    Ruiz, J A; Pérez-Vendrell, A M; Esteve-Garcia, E

    2000-05-01

    1. An experiment was carried out to determine the effect of removal of supplemental iron and copper from broiler diets during the last 3 weeks before slaughter on broiler performance, tissue vitamin E concentrations and oxidation values in raw; cooked and stored broiler leg meat. 2. Removal of supplemental iron and copper from the diet slightly decreased food efficiency; the differences were significant only when both minerals were removed simultaneously 3. Effect of iron withdrawal on iron concentration in tissue was low. However, total copper concentration in tissue was reduced in animals deprived of iron or both minerals simultaneously. 4. Removal of dietary iron and copper did not affect vitamin E concentration in raw and cooked meat, while stored meat showed lower concentrations in animals deprived of iron and copper simultaneously. 5. The removal of iron and copper from the diet reduced oxidation values in cooked broiler leg meat as measured by the thiobarbituric acid-reacting substances method (TBARS).

  10. Clinical efficacy of two forms of intravenous iron--saccharated ferric oxide and cideferron--for iron deficiency anemia.

    PubMed

    Araki, T; Takaai, M; Miyazaki, A; Ohshima, S; Shibamiya, T; Nakamura, T; Yamamoto, K

    2012-12-01

    Over 90% of iron deficiency anemia cases are due to iron deficiency associated with depletion of stored iron or inadequate intake. Parenteral iron supplementation is an important part of the management of anemia, and some kinds of intravenous iron are used. However, few studies have evaluated the clinical efficacy of these drugs. The purpose of this study was to compare and assess the clinical efficacy of two types of intravenous iron injection, saccharated ferric oxide (SFO) and cideferron (CF). Medical records were obtained for 91 unrelated Japanese anemia patients treated with SFO (n = 37) or CF (n = 54) from May 2005 to May 2010 at Gunma University Hospital. Patients treated with blood transfusion, erythropoietin or oral iron were excluded. Hemoglobin (Hb) values measured on day 0, 7 and 14 were used to assess the efficacy of intravenous irons. A significant increase was observed in the mean Hb value by day 14 of administration in both the CF group and SFO group, and the mean Hb increase due to administration of CF for 7 days was comparable to that of SFO for 14 days. Age and sex did not affect improvement of Hb value. CF is fast acting and highly effective compared with SFO for the treatment of iron deficiency anemia. The use of CF may shorten a therapeutic period for iron deficiency anemia, and CF may be feasible for reducing the hospitalization period.

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

    PubMed

    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

  12. Iron isotope fractionation during microbial dissimilatory iron oxide reduction in simulated Archaean seawater.

    PubMed

    Percak-Dennett, E M; Beard, B L; Xu, H; Konishi, H; Johnson, C M; Roden, E E

    2011-05-01

    The largest Fe isotope excursion yet measured in marine sedimentary rocks occurs in shales, carbonates, and banded iron formations of Neoarchaean and Paleoproterozoic age. The results of field and laboratory studies suggest a potential role for microbial dissimilatory iron reduction (DIR) in producing this excursion. However, most experimental studies of Fe isotope fractionation during DIR have been conducted in simple geochemical systems, using pure Fe(III) oxide substrates that are not direct analogues to phases likely to have been present in Precambrian marine environments. In this study, Fe isotope fractionation was investigated during microbial reduction of an amorphous Fe(III) oxide-silica coprecipitate in anoxic, high-silica, low-sulphate artificial Archaean seawater at 30 °C to determine if such conditions alter the extent of reduction or isotopic fractionations relative to those observed in simple systems. The Fe(III)-Si coprecipitate was highly reducible (c. 80% reduction) in the presence of excess acetate. The coprecipitate did not undergo phase conversion (e.g. to green rust, magnetite or siderite) during reduction. Iron isotope fractionations suggest that rapid and near-complete isotope exchange took place among all Fe(II) and Fe(III) components, in contrast to previous work on goethite and hematite, where exchange was limited to the outer few atom layers of the substrate. Large quantities of low-δ(56)Fe Fe(II) (aqueous and solid phase) were produced during reduction of the Fe(III)-Si coprecipitate. These findings shed new light on DIR as a mechanism for producing Fe isotope variations observed in Neoarchaean and Paleoproterozoic marine sedimentary rocks. © 2011 Blackwell Publishing Ltd.

  13. Iron oxide reduction in deep Baltic Sea sediments: the potential role of anaerobic oxidation of methane

    NASA Astrophysics Data System (ADS)

    Egger, Matthias; Slomp, Caroline P.; Dijkstra, Nikki; Sapart, Célia J.; Risgaard-Petersen, Nils; Kasten, Sabine; Riedinger, Natascha; Barker Jørgensen, Bo

    2015-04-01

    Methane is a powerful greenhouse gas and its emission from marine sediments to the atmosphere is largely controlled by anaerobic oxidation of methane (AOM). Traditionally, sulfate is considered to be the most important electron acceptor for AOM in marine sediments. However, recent studies have shown that AOM may also be coupled to the reduction of iron (Fe) oxides (Beal et al., 2009; Riedinger et al., 2014; Egger et al., 2014). In the Baltic Sea, the transition from the Ancylus freshwater phase to the Littorina brackish/marine phase (A/L-transition) ca. 9-7 ka ago (Zillén et al., 2008) resulted in the accumulation of methanogenic brackish/marine sediments overlying Fe-oxide rich lacustrine deposits. The downward diffusion of methane from the brackish/marine sediments into the lake sediments leads to an ideal diagenetic system to study a potential coupling between Fe oxide reduction and methane oxidation. Here, we use porewater and sediment geochemical data obtained at sites M0063 and M0065 during the IODP Baltic Sea Paleoenvironment Expedition 347 in 2013 to identify the potential mechanisms responsible for the apparent Fe oxide reduction in the non-sulfidic limnic sediments below the A/L transition. In this presentation, we will review the various explanations for the elevated ferrous Fe in the porewater in the lake sediments and we will specifically address the potential role of the reaction of methane with Fe-oxides. References: Beal E. J., House C. H. and Orphan V. J. (2009) Manganese- and iron-dependent marine methane oxidation. Science 325, 184-187. Egger M., Rasigraf O., Sapart C. J., Jilbert T., Jetten M. S. M., Röckmann T., van der Veen C., Banda N., Kartal B., Ettwig K. F. and Slomp C. P. (2014) Iron-mediated anaerobic oxidation of methane in brackish coastal sediments. Environ. Sci. Technol. 49, 277-283. Riedinger N., Formolo M. J., Lyons T. W., Henkel S., Beck A. and Kasten S. (2014) An inorganic geochemical argument for coupled anaerobic oxidation of

  14. Chemical characterization of iron oxide precipitates from wetlands constructed to treat polluted mine drainage

    SciTech Connect

    Fish, C.L.; Partezana, J.M.; Hedin, R.S.

    1996-12-31

    The passive treatment of abandoned mine drainage using wetlands will produce a significant amount of iron rich sludge which will require costly removal and disposal. An alternative to disposal may be the use of this iron oxide material as pigments which could defray some of these costs. In this research, iron deposits from five alkaline mine drainage wetlands were collected and a series of standard tests were run. The tests included loss on ignition, moisture, pH, acid soluble metals, oil absorption, and water soluble matter. The results of these tests were compared to those achieved using commercially available natural and synthetic iron oxides. The results indicate that iron oxides from constructed wetlands have chemical properties that are intermediate to those of natural and synthetic iron oxide products.

  15. Absorption of inorganic halides produced from Freon 12 by calcium carbonate containing iron(III) oxide

    SciTech Connect

    Imamura, Seiichiro; Matsuba, Yoichi; Yamada, Etsu; Takai, Kenji; Utani, Kazunori

    1997-09-01

    Inorganic halides produced by the catalytic decomposition of Freon 12 were fixed by calcium carbonate, which is the main component of limestone. Iron(III) oxide, which is present as a contaminant in limestone, promoted the absorption of the halides by calcium carbonate at low temperatures. The supposed action of iron(III) oxide was to first react with inorganic halides, forming iron halides, and, then, transfer them to calcium carbonate to replace carbonate ion in a catalytic way. Thus, calcium carbonate containing iron oxides (limestone) can be used as an effective absorbent for the inorganic halogens produced during the decomposition of Freons.

  16. Oxygen vacancy promoted methane partial oxidation over iron oxide oxygen carriers in the chemical looping process.

    PubMed

    Cheng, Zhuo; Qin, Lang; Guo, Mengqing; Xu, Mingyuan; Fan, Jonathan A; Fan, Liang-Shih

    2016-11-30

    We perform ab initio DFT+U calculations and experimental studies of the partial oxidation of methane to syngas on iron oxide oxygen carriers to elucidate the role of oxygen vacancies in oxygen carrier reactivity. In particular, we explore the effect of oxygen vacancy concentration on sequential processes of methane dehydrogenation, and oxidation with lattice oxygen. We find that when CH4 adsorbs onto Fe atop sites without neighboring oxygen vacancies, it dehydrogenates with CHx radicals remaining on the same site and evolves into CO2via the complete oxidation pathway. In the presence of oxygen vacancies, on the other hand, the formed methyl (CH3) prefers to migrate onto the vacancy site while the H from CH4 dehydrogenation remains on the original Fe atop site, and evolves into CO via the partial oxidation pathway. The oxygen vacancies created in the oxidation process can be healed by lattice oxygen diffusion from the subsurface to the surface vacancy sites, and it is found that the outward diffusion of lattice oxygen atoms is more favorable than the horizontal diffusion on the same layer. Based on the proposed mechanism and energy profile, we identify the rate-limiting steps of the partial oxidation and complete oxidation pathways. Also, we find that increasing the oxygen vacancy concentration not only lowers the barriers of CH4 dehydrogenation but also the cleavage energy of Fe-C bonds. However, the barrier of the rate-limiting step cannot further decrease when the oxygen vacancy concentration reaches 2.5%. The fundamental insight into the oxygen vacancy effect on CH4 oxidation with iron oxide oxygen carriers can help guide the design and development of more efficient oxygen carriers and CLPO processes.

  17. TNF-α-stimulated macrophages protect A549 lung cells against iron and oxidation.

    PubMed

    Persson, H Lennart; Vainikka, Linda K; Eriksson, Ida; Wennerström, Urban

    2013-01-01

    Previously, we have shown that TNF-α protects iron-exposed J774 macrophages against iron-catalyzed oxidative lysosomal disruption and cell death by increasing reduced glutathione and H-ferritin in cells. Because J774 cells are able to harbor large amounts of iron, which is potentially harmful in a redox-active state, we hypothesized that TNF-α-stimulated J774 macrophages will prevent iron-driven oxidative killing of alveolar epithelial A549 cells in co-culture. In the present study, iron trichloride (which is endocytosed by cells as hydrated iron-phosphate complexes) was mainly deposited inside the lysosomes of J774 macrophages, while A549 cells, equally iron exposed, accumulated much less iron. When challenged by oxidants, however, reactive lysosomal iron in A549 cells promoted lysosomal disruption and cell death, particularly in the presence of TNF-α. This effect resulted from an elevation in ROS generation by TNF-α, while a compensatory upregulation of protective molecules (H-ferritin and/or reduced glutathione) by TNF-α was absent. A549 cell death was particularly pronounced when iron and TNF-α were present in the conditioned medium during oxidant challenge; thus, iron-driven oxidative reactions in the culture medium were a much greater hazard to A549 cells than those taking place inside their lysosomes. Consequently, the iron chelator, deferoxamine, efficiently prevented A549 cell death when added to the culture medium during an oxidant challenge. In co-cultures of TNF-α-stimulated lung cells, J774 macrophages sequestered iron inside their lysosomes and protected A549 cells from oxidative reactions and cell death. Thus, the collective effect of TNF-α on co-cultured lung cells was mainly cytoprotective. Copyright © 2011 Elsevier GmbH. All rights reserved.

  18. 40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., carboxylic acid-modified (generic). 721.10529 Section 721.10529 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid... substance identified generically as cobalt iron manganese oxide, carboxylic acid-modified (PMN P-12-35) is...

  19. Kinetic Studies of Iron Oxidation by Whole Cells of Ferrobacillus ferrooxidans

    PubMed Central

    Schnaitman, C. A.; Korczynski, M. S.; Lundgren, D. G.

    1969-01-01

    A colorimetric assay was developed for studying the kinetics of iron oxidation with whole cells of the chemoautotroph, Ferrobacillus ferrooxidans. The assay was more advantageous than the conventional method of Warburg manometry because of its simplicity, rapidity, and the small amount of cells required. The assay measured Fe3+ as a chloride complex which absorbs at 410 nm. Kinetic analysis showed the apparent Km for iron oxidation to be 5.4 × 10−3m in an unbuffered system and 2.2 × 10−3m in the presence of β-alanine-SO42− buffer. Glycine and β-alanine buffers were used in the measurement of the pH optimum for iron oxidation; the optimum ranged from 2.5 to 3.8. The effect of pH was primarily on the Vmax while the Km remained constant. Added SO42− was found to stimulate iron oxidation by increasing the Vmax of iron oxidation by whole cells, but it did not affect the Km. Results of assays of iron oxidation in systems containing various mole percentages of SO42− and Cl− indicated that Cl− did not inhibit iron oxidation but that SO42− was required. Sulfate could be partially replaced by HPO42− and HAsO42− but not by BO3−, MoO42−, NO3−, or Cl−; formate and MoO42− inhibited iron oxidation. PMID:5808080

  20. Iron-Oxide Minerals Affect Extracellular Electron-Transfer Paths of Geobacter spp

    PubMed Central

    Kato, Souichiro; Hashimoto, Kazuhito; Watanabe, Kazuya

    2013-01-01

    Some bacteria utilize (semi)conductive iron-oxide minerals as conduits for extracellular electron transfer (EET) to distant, insoluble electron acceptors. A previous study demonstrated that microbe/mineral conductive networks are constructed in soil ecosystems, in which Geobacter spp. share dominant populations. In order to examine how (semi)conductive iron-oxide minerals affect EET paths of Geobacter spp., the present study grew five representative Geobacter strains on electrodes as the sole electron acceptors in the absence or presence of (semi)conductive iron oxides. It was found that iron-oxide minerals enhanced current generation by three Geobacter strains, while no effect was observed in another strain. Geobacter sulfurreducens was the only strain that generated substantial amounts of currents both in the presence and absence of the iron oxides. Microscopic, electrochemical and transcriptomic analyses of G. sulfurreducens disclosed that this strain constructed two distinct types of EET path; in the absence of iron-oxide minerals, bacterial biofilms rich in extracellular polymeric substances were constructed, while composite networks made of mineral particles and microbial cells (without polymeric substances) were developed in the presence of iron oxides. It was also found that uncharacterized c-type cytochromes were up-regulated in the presence of iron oxides that were different from those found in conductive biofilms. These results suggest the possibility that natural (semi)conductive minerals confer energetic and ecological advantages on Geobacter, facilitating their growth and survival in the natural environment. PMID:23363619

  1. Dietary Iron Oxide Nanoparticles Delay Aging and Ameliorate Neurodegeneration in Drosophila.

    PubMed

    Zhang, Yi; Wang, Zhuyao; Li, Xiaojiao; Wang, Lu; Yin, Min; Wang, Lihua; Chen, Nan; Fan, Chunhai; Song, Haiyun

    2016-02-17

    Dietary iron oxide nanoparticles are shown to ameliorate neurodegeneration in a Drosophelia Alzheimer's disease model. Iron oxide nanoparticles can mimic catalase and can decompose reactive oxygen species (ROS). This has potential therapeutic uses for aging, metabolic disorders, and neurodegenerative diseases, in which increased production of ROS is closely implicated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Dopamine Serves as a Stable Surface Modifier for Iron Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chi, Xiaoqin; Wang, Xiaomin; Hu, Juan; Wang, Lirong; Gao, Jinhao; Zhang, Bei; Zhang, Xixiang

    2013-03-01

    Iron oxide nanoparticles are an important class of nanomaterials in a broad range of biomedical applications because of their superparamagnetism and biocompatibility. The success of biomedical applications of iron oxide nanoparticles relies on the particles' surface functionalization, which requires robust and versatile surface anchors. Here, we report on a detailed examination of the dopamine-based surface modification of iron oxide nanoparticles. We used dopamine (2-(3,4-dihydroxyphenyl)ethylamine) and L-dopa (3,4-dihydroxy-L-phenylalanine) as two surface modifiers and chose Fe2O3 hollow nanoparticles and Fe3O4 nanoparticles as two representative substrates. Optical and TEM images showed that iron oxide nanoparticles dispersed very well in water after surface modification. The analysis of the UV-Vis spectra indicated that dopamine and L-dopa are stable after being immobilized on the surface of iron oxide nanoparticles when the pH value of the environment is about 7. The magnetic properties analysis further showed that the blocking temperature of the dopamine- or L-dopa-decorated iron oxide nanoparticles hardly changed over 20 days, confirming long-term stability of these surface modified nanoparticles. Cell assay indicated that these dopamine- or L-dopa-modified iron oxide nanoparticles were biocompatible. These results confirm that dopamine serves as a stable modifier and a robust anchor to functionalize iron oxide nanoparticles in biomedical applications.

  3. Genome Sequence of the Acidophilic Iron Oxidizer Ferrimicrobium acidiphilum Strain T23T.

    PubMed

    Eisen, Sebastian; Poehlein, Anja; Johnson, D Barrie; Daniel, Rolf; Schlömann, Michael; Mühling, Martin

    2015-04-30

    Extremely acidophilic iron-oxidizing bacteria have largely been characterized for the phyla Proteobacteria and Nitrospira. Here, we report the draft genome of an iron-oxidizing and -reducing heterotrophic mesophile of the Actinobacteria, Ferrimicrobium acidiphilum, which was isolated from an abandoned pyrite mine. The genome sequence comprises 3.08 Mb.

  4. Catalytic oxidation of alkanes by iron bispidine complexes and dioxygen: oxygen activation versus autoxidation.

    PubMed

    Comba, Peter; Lee, Yong-Min; Nam, Wonwoo; Waleska, Arkadius

    2014-01-14

    Organic substrates (specifically cis-1,2-dimethylcyclohexane, DMCH) are oxidized by O2 in the presence of iron(II)-bispidine complexes. It is shown that this oxidation reaction is not based on O2 activation by the nonheme iron catalysts as in Nature but due to a radical-based initiation, followed by a radical- and ferryl-based catalytic reaction.

  5. Iron-oxide minerals affect extracellular electron-transfer paths of Geobacter spp.

    PubMed

    Kato, Souichiro; Hashimoto, Kazuhito; Watanabe, Kazuya

    2013-01-01

    Some bacteria utilize (semi)conductive iron-oxide minerals as conduits for extracellular electron transfer (EET) to distant, insoluble electron acceptors. A previous study demonstrated that microbe/mineral conductive networks are constructed in soil ecosystems, in which Geobacter spp. share dominant populations. In order to examine how (semi)conductive iron-oxide minerals affect EET paths of Geobacter spp., the present study grew five representative Geobacter strains on electrodes as the sole electron acceptors in the absence or presence of (semi)conductive iron oxides. It was found that iron-oxide minerals enhanced current generation by three Geobacter strains, while no effect was observed in another strain. Geobacter sulfurreducens was the only strain that generated substantial amounts of currents both in the presence and absence of the iron oxides. Microscopic, electrochemical and transcriptomic analyses of G. sulfurreducens disclosed that this strain constructed two distinct types of EET path; in the absence of iron-oxide minerals, bacterial biofilms rich in extracellular polymeric substances were constructed, while composite networks made of mineral particles and microbial cells (without polymeric substances) were developed in the presence of iron oxides. It was also found that uncharacterized c-type cytochromes were up-regulated in the presence of iron oxides that were different from those found in conductive biofilms. These results suggest the possibility that natural (semi)conductive minerals confer energetic and ecological advantages on Geobacter, facilitating their growth and survival in the natural environment.

  6. Nitric oxide and respiratory rhythm in mammals: a new modulator of phase transition?

    PubMed

    Pierrefiche, O; Abdala, A P L; Paton, J F R

    2007-11-01

    NO (nitric oxide) modulates several central pattern generators, but its role in respiratory rhythmogenesis and its mode of action on medullary respiratory neurons during normoxia are unknown. We analysed the actions of NO on the mammalian respiratory network at the system and cellular levels. Given systemically, the NO donor diethylamine NONOate increased post-inspiratory duration in vagus, phrenic and hypoglossal nerves, whereas blockade of NO generation with L-NAME (N(G)-nitro-L-arginine methyl ester) produced the opposite response. At the cellular level, we pressure-ejected the NO donor on to respiratory neurons. NO had both inhibitory and excitatory effects on all types of respiratory neurons. Inhibitory effects involved soluble guanylate cyclase, as they were blocked with ODQ (1H-[1,2,4]oxadiazolo[4,3a]quinoxalin-1-one), whereas excitations were antagonized by uric acid and possibly mediated via peroxynitrite. Importantly, NO facilitated both GABA (gamma-aminobutyric acid)- and NMDA (N-methyl-D-aspartate)-induced neuronal responses, but this was restricted to post-inspiratory and pre-inspiratory neurons; other neuron types showed additive effects only. Our results support NO as modulator of centrally generated respiratory activity and specifically of ligand-mediated responses in respiratory neuron types involved in respiratory phase transition.

  7. Iron Binding at Specific Sites within the Octameric HbpS Protects Streptomycetes from Iron-Mediated Oxidative Stress

    PubMed Central

    Wedderhoff, Ina; Kursula, Inari; Groves, Matthew R.; Ortiz de Orué Lucana, Darío

    2013-01-01

    The soil bacterium Streptomyces reticuli secretes the octameric protein HbpS that acts as a sensory component of the redox-signalling pathway HbpS-SenS-SenR. This system modulates a genetic response on iron- and haem-mediated oxidative stress. Moreover, HbpS alone provides this bacterium with a defence mechanism to the presence of high concentrations of iron ions and haem. While the protection against haem has been related to its haem-binding and haem-degrading activity, the interaction with iron has not been studied in detail. In this work, we biochemically analyzed the iron-binding activity of a set of generated HbpS mutant proteins and present evidence showing the involvement of one internal and two exposed D/EXXE motifs in binding of high quantities of ferrous iron, with the internal E78XXE81 displaying the tightest binding. We additionally show that HbpS is able to oxidize ferrous to ferric iron ions. Based on the crystal structure of both the wild-type and the mutant HbpS-D78XXD81, we conclude that the local arrangement of the side chains from the glutamates in E78XXE81 within the octameric assembly is a pre-requisite for interaction with iron. The data obtained led us to propose that the exposed and the internal motif build a highly specific route that is involved in the transport of high quantities of iron ions into the core of the HbpS octamer. Furthermore, physiological studies using Streptomyces transformants secreting either wild-type or HbpS mutant proteins and different redox-cycling compounds led us to conclude that the iron-sequestering activity of HbpS protects these soil bacteria from the hazardous side effects of peroxide- and iron-based oxidative stress. PMID:24013686

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

    PubMed

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

    2016-12-01

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

  9. Porous Iron Oxide Ribbons Grown on Graphene for High-Performance Lithium Storage

    PubMed Central

    Yang, Shubin; Sun, Yi; Chen, Long; Hernandez, Yenny; Feng, Xinliang; Müllen, Klaus

    2012-01-01

    A well-designed nanostructure of transition metal oxides has been regarded as a key to solve their problems of large volume changes during lithium insertion-desertion processes which are associated with pulverization of the electrodes and rapid capacity decay. Here we report an effective approach for the fabrication of porous iron oxide ribbons by controlling the nucleation and growth of iron precursor onto the graphene surface and followed by an annealing treatment. The resultant iron oxide ribbons possess large aspect ratio, porous structure, thin feature and enhanced open-edges. These characteristics are favorable for the fast diffusion of lithium ions and electrons, and meanwhile can effectively accommodate the volume change of iron oxides during the cycling processes. As a consequence, the graphene-induced porous iron oxide ribbons exhibit a high reversible capacity and excellent cycle stability for lithium storage. PMID:22645643

  10. The concept of delayed nucleation in nanocrystal growthdemonstrated for the case of iron oxide nanodisks

    SciTech Connect

    Casula, Maria F.; Jun, Young-wook; Zaziski, David J.; Chan, EmoryM.; Corrias, Anna; Alivisatos, Paul A.

    2005-09-09

    A comprehensive study of iron oxide nanocrystal growth through non-hydrolitic, surfactant-mediated thermal reaction of iron pentacarbonyl and an oxidizer has been conducted, which includes size control, anisotropic shape evolution, and crystallographic phase transition of monodisperse iron oxide colloidal nanocrystals. The reaction was monitored by in situ UV-Vis spectroscopy taking advantage of the color change accompanying the iron oxide colloid formation allowing measurement of the induction time for nucleation. Features of the synthesis such as the size control and reproducibility are related to the occurrence of the observed delayed nucleation process. As a separate source of iron and oxygen is adopted, phase control could also be achieved by sequential injections of oxidizer.

  11. Iron(3) oxide-based nanoparticles as catalysts in advanced organic aqueous oxidation.

    PubMed

    Zelmanov, Grigory; Semiat, Raphael

    2008-01-01

    Water contaminated with dissolved organic matter is an important issue to resolve for all-purpose uses. The catalytic behavior of iron-based nanocatalysts was investigated for the treatment of contaminated water in the advanced chemical oxidation process. In this study, typical organic contaminants, such as ethylene glycol and phenol, were chosen to simulate common contaminants. It was shown that the two substances are efficiently destroyed by the Fenton-like reaction using iron(3) oxide-based nanocatalysts in the presence of hydrogen peroxide without the need for UV or visible radiation sources at room temperature. A strong effect of nanocatalyst concentration on reaction rate was shown. The kinetic reaction was found and the reaction rate coefficient k was calculated.

  12. Cadmium complexation by bacteriogenic iron oxides from a subterranean environment.

    PubMed

    Martinez, Raul E; Pedersen, Karsten; Ferris, F Grant

    2004-07-01

    This study quantifies the metal sorption characteristics of subterranean bacteriogenic iron oxides (BIOS) and their organic phases (intermixed intact and fragmented bacteria). A Cd2+ ion-selective electrode was used to generate high-resolution metal sorption data as a function of increasing pH. A multisite Langmuir model, along with a linear programming regression method (LPM), was applied to fit experimental data. This approach found two discrete Cd2+ binding sites for the BIOS with average -log10 equilibrium constants (pK(S,j)) of 1.06 +/- 0.19 and 2.24 +/- 0.28. Three discrete sites were obtained for the bacterial fraction, with pK(S,j) values of -0.05 +/- 0.12, 1.18 +/- 0.02, and 3.81 +/- 0.16. This indicated that the BIOS surface had a lower affinity for Cd2+ than that of the bacteria. pK(S,j) values for the BIOS were similar to those reported for pure iron oxide phases, while the organic fraction pK(S,j) spectrum was consistent with previous spectra for intact bacteria. Individual binding site densities of 0.04 +/- 0.01 and 0.05 +/- 0.02 and 0.29 +/- 0.05, 0.11 +/- 0.01, and 0.09 +/- 0.02 micromol/mg of BIOS corresponded to the iron oxide mixture and bacteria fraction, respectively. These values indicated high concentrations of strong affinity Cd2+ complexing groups on the bacterial surface. Comparison of total site densities of 0.08 +/- 0.02 and 0.48 +/- 0.06 micromol/mg of BIOS for the mixture and the bacterial phase, respectively, suggested a nonadditive character for the BIOS surface reactivity. This was emphasized by a higher affinity for Cd2+, as well as an increase in total site concentration observed for the bacterial phase. LPM was able to distinguish between the BIOS mixture and its organic fraction Cd2+ complexation characteristics. This approach is therefore a useful tool for the study of natural sorbent materials controlling metal partitioning in contaminated and pristine environments.

  13. Iron oxidation in Mops buffer. Effect of EDTA, hydrogen peroxide and FeCl3.

    PubMed

    Tadolini, B

    1987-01-01

    The effect of EDTA and H2O2 on iron autoxidation in Mops buffer depends on the pH of the solution. At acidic pH, EDTA caused the oxidation of a stoichiometric amount of iron. At neutral and alkaline pH, EDTA and H2O2 not only oxidizes a stoichiometric amount of iron but also causes the oxidation of the Fe2+ exceeding the concentration of these compounds. In the presence of EDTA, oxidation of Fe2+ in exceeding the concentration of these compounds has a shorter lag phase and an increased rate compared with that in the absence. The solution develops a yellow colour whose intensity is proportional to the amount of Fe2+ exceeding the concentration of these compounds in solution. When the reaction is conducted in the presence of NBT, formazan formation is greatly reduced compared to the control without EDTA and H2O2. The Fe3+-EDTA complex and Fe3+ affected iron oxidation, development of the yellow colour and NBT reduction in a similar fashion. In all these experimental conditions, iron oxidation is greatly reduced in the presence of mannitol, sorbitol and catalase. In phosphate buffer, EDTA oxidized a stoichiometric amount of iron without affecting free Fe2+ oxidation. Fe3+ has no effect on iron oxidation in this buffer.

  14. Iron oxide nanoparticles for magnetically assisted patterned coatings

    NASA Astrophysics Data System (ADS)

    Dodi, Gianina; Hritcu, Doina; Draganescu, Dan; Popa, Marcel I.

    2015-08-01

    Iron oxide nanoparticles able to magnetically assemble during the curing stage of a polymeric support to create micro-scale surface protuberances in a controlled manner were prepared and characterized. The bare Fe3O4 particles were obtained by two methods: co-precipitation from an aqueous solution containing Fe3+/Fe2+ ions with a molar ratio of 2:1 and partial oxidation of ferrous ions in alkaline conditions. The products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetization measurement. They were subsequently functionalized using oleic acid, sodium oleate, or non-ionic surfactant mixtures with various hydrophilic to lipophilic balance (HLB) values. Composite nanoparticle-polymer films prepared by spraying were deposited and cured by drying on glass slides under a static magnetic field in the range of 1.5-5.5 mT. Magnetic field generated surface roughness was evidenced by optical and scanning electron microscopy. The optimum hierarchical patterning was obtained with the nanoparticles produced by partial oxidation and functionalized with hydrophobic surfactants. Possible applications may include ice-phobic composite coatings.

  15. Solution voltammetry of 4 nm magnetite iron oxide nanoparticles.

    PubMed

    Roberts, Joseph J P; Westgard, John A; Cooper, Laura M; Murray, Royce W

    2014-07-30

    The voltammetry of solution-dispersed magnetite iron oxide Fe3O4 nanoparticles is described. Their currents are controlled by nanoparticle transport rates, as shown with potential step chronoamperometry and rotated disk voltammetry. In pH 2 citrate buffer with added NaClO4 electrolyte, solution cyclic voltammetry of these nanoparticles (average diameter 4.4 ± 0.9 nm, each containing ca. 30 Fe sites) displays an electrochemically irreversible oxidation with E(PEAK) at ca. +0.52 V and an irreversible reduction with E(PEAK) at ca. +0.2 V vs Ag/AgCl reference electrode. These processes are presumed to correspond to the formal potentials for one-electron oxidation of Fe(II) and reduction of Fe(III) at their different sites in the magnetite nanoparticle structure. The heterogeneous electrode reaction rates of the nanoparticles are very slow, in the 10(-5) cm/s range. The nanoparticles are additionally characterized by a variety of tools, e.g., TEM, UV/vis, and XPS spectroscopies.

  16. Processing, Microstructure, and Oxidation Behavior of Iron Foams

    NASA Astrophysics Data System (ADS)

    Park, Hyeji; Noh, Yoonsook; Choi, Hyelim; Hong, Kicheol; Kwon, Kyungjung; Choe, Heeman

    2016-09-01

    With its historically long popularity in major structural applications, the use of iron (Fe) has also recently begun to be explored as an advanced functional material. For this purpose, it is more advantageous to use Fe as a porous structure, simply because it can provide a greater surface area and a higher reaction rate. This study uses a freeze-casting method, which consists of simple and low-cost processing steps, to produce Fe foam with a mean pore size of 10 μm. We examine the influences of various parameters ( i.e., mold bottom temperature, powder content, and sintering time) on the processing of Fe foam, along with its oxidation kinetics at 823 K (550 °C) with various heat-treatment times. We confirm that Fe2O3 and Fe3O4 oxide layers are successfully formed on the surface of Fe foam. With the Fe oxide layers as an active anode material, the Fe foam can potentially be used as a three-dimensional anode current collector for an advanced lithium-ion battery.

  17. Iron and carbon metabolism by a mineral-oxidizing Alicyclobacillus-like bacterium.

    PubMed

    Yahya, Adibah; Hallberg, Kevin B; Johnson, D Barrie

    2008-04-01

    A novel iron-oxidizing, moderately thermophilic, acidophilic bacterium (strain "GSM") was isolated from mineral spoil taken from a gold mine in Montana. Biomolecular analysis showed that it was most closely related to Alicyclobacillus tolerans, although the two bacteria differed in some key respects, including the absence (in strain GSM) of varpi-alicyclic fatty acids and in their chromosomal base compositions. Isolate GSM was able to grow in oxygen-free media using ferric iron as terminal electron acceptor confirming that it was a facultative anaerobe, a trait not previously described in Alicyclobacillus spp.. The acidophile used both organic and inorganic sources of energy and carbon, although growth and iron oxidation by isolate GSM was uncoupled in media that contained both fructose and ferrous iron. Fructose utilization suppressed iron oxidation, and oxidation of ferrous iron occurred only when fructose was depleted. In contrast, fructose catabolism was suppressed when bacteria were harvested while actively oxidizing iron, suggesting that both ferrous iron- and fructose-oxidation are inducible in this acidophile. Isolate GSM accelerated the oxidative dissolution of pyrite in liquid media either free of, or amended with, organic carbon, although redox potentials were significantly different in these media. The potential of this isolate for commercial mineral processing is discussed.

  18. Identification of a membrane cytochrome c from neutrophilic, iron-oxidizing Mariprofundus ferrooxydans, strain PV-1

    NASA Astrophysics Data System (ADS)

    Barco, R. A.; Zhong, J.; Ramirez, G. A.; Reese, B. K.; Edwards, K. J.

    2012-12-01

    Neutrophilic-iron oxidizing bacteria (FeOB) are a group of bacteria that can oxidize iron at -or near neutral pH, making them relevant in habitats with naturally high levels of reduced iron (i.e. Fe2+) such as hydrothermal vents. In the ocean, microorganisms in the Mariprofundus genus (zeta- Proteobacteria) are the only known organisms to chemolithoautotrophically oxidize iron. In order to identify the active bacterial oxidation of iron in the environment (i.e. in the deep biosphere), biomarkers for this functionality are needed. The aim of this study is to confirm the expression of potential functional biomarkers that are diagnostic of neutrophilic bacterial iron-oxidation. To this end, Mariprofundus ferrooxydans, strain PV-1 was cultivated in large batches and its proteins extracted via a methodology to circumvent protein binding to filamentous material. Proteins were assayed for redox-activity and for iron-oxidation activity. The bands of the gel that showed activity were analyzed via LC-MS/MS for identification of peptides and subsequently protein-matched to the M. ferrooxydans proteome database. The results indicate that a membrane cytochrome c with homology to the iron-oxidizing Cyt572 from Leptospirillum Group II is expressed in M. ferrooxydans when it is active. Other proteins associated with the electron transport chain of M. ferroxydans such as cbb3-type cytochrome oxidase subunits were identified and validated separately through reverse transcription followed by PCR amplification.

  19. Mitochondrial ferritin limits oxidative damage regulating mitochondrial iron availability: hypothesis for a protective role in Friedreich ataxia

    PubMed Central

    Campanella, Alessandro; Rovelli, Elisabetta; Santambrogio, Paolo; Cozzi, Anna; Taroni, Franco; Levi, Sonia

    2009-01-01

    Mitochondrial ferritin (FtMt) is a nuclear-encoded iron-sequestering protein that specifically localizes in mitochondria. In mice it is highly expressed in cells characterized by high-energy consumption, while is undetectable in iron storage tissues like liver and spleen. FtMt expression in mammalian cells was shown to cause a shift of iron from cytosol to mitochondria, and in yeast it rescued the defects associated with frataxin deficiency. To study the role of FtMt in oxidative damage, we analyzed the effect of its expression in HeLa cells after incubation with H2O2 and Antimycin A, and after a long-term growth in glucose-free media that enhances mitochondrial respiratory activity. FtMt reduced the level of reactive oxygen species (ROS), increased the level of adenosine 5'triphosphate and the activity of mitochondrial Fe-S enzymes, and had a positive effect on cell viability. Furthermore, FtMt expression reduces the size of cytosolic and mitochondrial labile iron pools. In cells grown in glucose-free media, FtMt level was reduced owing to faster degradation rate, however it still protected the activity of mitochondrial Fe-S enzymes without affecting the cytosolic iron status. In addition, FtMt expression in fibroblasts from Friedreich ataxia (FRDA) patients prevented the formation of ROS and partially rescued the impaired activity of mitochondrial Fe-S enzymes, caused by frataxin deficiency. These results indicate that the primary function of FtMt involves the control of ROS formation through the regulation of mitochondrial iron availability. They are consistent with the expression pattern of FtMt observed in mouse tissues, suggesting a FtMt protective role in cells characterized by defective iron homeostasis and respiration, such as in FRDA. PMID:18815198

  20. Effect of oxidative stress on respiratory epithelium from children with Down syndrome.

    PubMed

    Bruijn, Martijn; Lutter, René; Eldering, Eric; Bos, Albert P; van Woensel, Job B M

    2013-10-01

    Children with Down syndrome are at high risk for acute respiratory distress syndrome. In Down syndrome, both regulation of inflammation and apoptosis, important in acute respiratory distress syndrome pathophysiology, are abnormal. This has been linked to an imbalance in free radical scavengers. We investigated the expression of free radical scavengers and the effect of oxidative stress in terms of apoptosis and inflammation in respiratory epithelium from children with Down syndrome compared with control subjects. We cultured primary nasal epithelial cells from Down syndrome children (n=12) and controls (n=17) and exposed them to oxidative stress by supplementing superoxide. First we showed that the expression of the free radical scavengers CuZn-superoxide dismutase was 28% higher (p=0.06), catalase was 36% lower (p=0.04) and glutathione peroxidase was 73% lower (p=0.004) in Down syndrome children compared with controls. We found no significant difference in apoptosis, between Down syndrome and control subjects after exposure to oxidative stress. We also found no significant difference in levels of interleukin (IL)-1β, IL-6, IL-8, vascular endothelial growth factor and granulocyte colony-stimulating factor in primary nasal epithelial cell supernatant after exposure to oxidative stress between Down syndrome and control subjects. We found an imbalance in free radical scavengers in respiratory epithelial cells from children with Down syndrome, but this did not result in increased levels of either apoptosis or inflammation upon exposure to oxidative stress.

  1. Arsenic removal from water using flame-synthesized iron oxide nanoparticles with variable oxidation states

    PubMed Central

    Abid, Aamir D.; Kanematsu, Masakazu; Young, Thomas M.; Kennedy, Ian M.

    2013-01-01

    We utilized gas-phase diffusion flame synthesis, which has potential for large-scale production of metal oxide nanoparticles, to produce iron oxide nanoparticles (IONPs) with variable oxidation states. The efficacy of these materials in removal of arsenate (As(V) ) from water was assessed. Two different flame configurations, a diffusion flame (DF) and an inverse diffusion flame (IDF), were employed to synthesize six different IONPs by controlling flame conditions. The IONPs produced in the IDF configuration (IDF-IONPs) had smaller particle diameters (4.8 – 8.2 nm) and larger surface areas (141–213 m2/g) than the IONPs produced in the DF configuration (29 nm, 36 m2/g), which resulted in their higher adsorption capacities. As(V) adsorption capacities of the IDF-IONPs increased when the IONPs were synthesized in more oxidizing conditions. The fully oxidized IDF-IONPs, maghemite (γ-Fe2O3), showed the highest As(V) adsorption capacity, comparable to that of magnetite nanocrystals synthesized by thermal decomposition of iron pentacarbonyl and equivalent to three to four times higher capacity than that of a commonly used goethite-based adsorbent. All IONPs were magnetically responsive, which is of great importance for solid−liquid separation. This study demonstrates that the IONPs synthesized in gas-phase flame, particularly IDF-IONPs, are excellent adsorbents because of their high As(V) sorption capacity, potential for large-scale production, and useful magnetic property. PMID:23645964

  2. Arsenic removal from water using flame-synthesized iron oxide nanoparticles with variable oxidation states.

    PubMed

    Abid, Aamir D; Kanematsu, Masakazu; Young, Thomas M; Kennedy, Ian M

    2013-02-01

    We utilized gas-phase diffusion flame synthesis, which has potential for large-scale production of metal oxide nanoparticles, to produce iron oxide nanoparticles (IONPs) with variable oxidation states. The efficacy of these materials in removal of arsenate (As(V) ) from water was assessed. Two different flame configurations, a diffusion flame (DF) and an inverse diffusion flame (IDF), were employed to synthesize six different IONPs by controlling flame conditions. The IONPs produced in the IDF configuration (IDF-IONPs) had smaller particle diameters (4.8 - 8.2 nm) and larger surface areas (141-213 m(2)/g) than the IONPs produced in the DF configuration (29 nm, 36 m(2)/g), which resulted in their higher adsorption capacities. As(V) adsorption capacities of the IDF-IONPs increased when the IONPs were synthesized in more oxidizing conditions. The fully oxidized IDF-IONPs, maghemite (γ-Fe2O3), showed the highest As(V) adsorption capacity, comparable to that of magnetite nanocrystals synthesized by thermal decomposition of iron pentacarbonyl and equivalent to three to four times higher capacity than that of a commonly used goethite-based adsorbent. All IONPs were magnetically responsive, which is of great importance for solid-liquid separation. This study demonstrates that the IONPs synthesized in gas-phase flame, particularly IDF-IONPs, are excellent adsorbents because of their high As(V) sorption capacity, potential for large-scale production, and useful magnetic property.

  3. Anthelmintic effects of zinc oxide and iron oxide nanoparticles against Toxocara vitulorum

    NASA Astrophysics Data System (ADS)

    Dorostkar, Ruhollah; Ghalavand, Majdedin; Nazarizadeh, Ali; Tat, Mahdi; Hashemzadeh, Mohammad Sadegh

    2017-04-01

    In the present study, zinc oxide (ZnO) and iron oxide (FeO) nanoparticles were examined for their possible, in vitro anthelmintic effects against Toxocara vitulorum. The worms were incubated for 24 h with different concentrations (0.004, 0.008 and 0.012% w/v) of the nanoparticles. The parasite mobility, mortality, superoxide dismutase (SOD) activity, malondialdehyde (MDA) and nitric oxide (NO) level were recorded at different time intervals. The results showed that both of the nanoparticles could significantly decrease worm's mobility, increase mortality rate as well as elevate MDA and NO content as compared to control group in a time- and concentration-dependent manner. SOD activity was elevated with the low concentration of the nanoparticles but it was decreased in higher ones. It can be concluded that ZnO and FeO nanoparticles exert their anthelmintic effects via induction of oxidative/nitrosative stress.

  4. Physical properties of new iron arsenide oxide with thick perovskite-type oxide layer

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Naoto; Ogino, Hiraku; Kishio, Koji; Shimoyama, Junichi

    2010-03-01

    Since the discovery of high-Tc superconductivity in LaFeAsO, a large number of layered compounds having anti-fluorite type Fe- or Ni-pnictide layer have been discovered. Among them, a series of pnictide oxides having perovskite-type oxide layersfootnotetextH. Ogino et al., Supercond. Sci. Technol. 22 (2009) 075008 are attractive because of their chemical flexibility particularly at the perovskite-type oxide layer, which may results in new compounds. In the present study, various physical properties have been investigated for the new iron pnictide oxides with thick perovskite-type blocking layers, i.e., large interlayer distance between Fe-layers more than 1.7 nm. These samples showed metallic and paramagnetic behaviors in resistivity and magnetization measurements, respectively, down to 2 K without any signs of superconductivity and other anomalies. Relationship among crystal structure, constituent elements and physical properties will be discussed for the newly discovered system.

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

    PubMed

    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

  6. Pilot scale application of nanosized iron oxides as electron acceptors for bioremediation

    NASA Astrophysics Data System (ADS)

    Bosch, Julian; Fritzsche, Andreas; Frank-Fahle, Beatrice; Lüders, Tilmann; Höss, Sebastian; Eisenmann, Heinrich; Held, Thomas; Totsche, Kai U.; Meckenstock, Rainer U.

    2014-05-01

    Microbial reduction of ferric iron is a major biogeochemical process in groundwater aquifer ecosystems and often associated with the degradation of organic contaminants, as bacteria couple iron reduction to the oxidation reduced carbon like e.g. BTEX. Yet in general the low bioavailability of natural iron oxides limits microbial reduction rates. However, nanosized iron oxides have an unequally enhanced bioavailability and reactivity compared to their respective bulk, macro-sized, and more crystalline materials. At the same time, nanosized iron oxides can be produced in stable colloidal suspensions, permitting efficient injections into contaminated aquifers. We examined the reactivity of nanosized synthetic colloidal iron oxides in microbial iron reduction. Application of colloidal nanoparticles led to a strong and sustainable enhancement of microbial reaction rates in batch experiments and sediment columns. Toluene oxidation was increased five-fold as compared to bulk, non-colloidal ferrihydrite as electron acceptor. Furthermore, we developed a unique approach for custom-tailoring the subsurface mobility of these particles after being injected into a contaminant plume. In a field pilot application, we injected 18 m3 of an iron oxide nanoparticle solution into a BTEX contaminated aquifer with a maximum excess pressure as low as 0.2 bar. The applied suspension showed a superior subsurface mobility, creating a reactive zone of 4 m height (corresponding to the height of the confined aquifer) and 6 m in diameter. Subsequent monitoring of BTEX, microbial BTEX degradation metabolites, ferrous iron generation, stable isotopes fractionation, microbial populations, and methanogenesis demonstrated the strong impact of our approach. Mathematic processed X-ray diffractograms and FTIR spectra provided a semi-quantitatively estimate of the long-term fate of the iron oxide colloids in the aquifer. Potential environmental risks of the injection itself were monitored with

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

    PubMed

    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

  8. Iron (Oxyhydr)Oxide Biosignatures in the Brushy Basin Member of the Jurassic Morrison Formation, Colorado Plateau, USA: Analog for Martian Diagenetic Iron

    NASA Astrophysics Data System (ADS)

    Potter-McIntyre, S. L.; Chan, M. A.; McPherson, B. J.

    2012-03-01

    Iron precipitates in modern microbial mats compared with iron cements in Jurassic alkaline saline lake sediments show that morphological and chemical biosignatures are present and preserved in oxidized, evaporative environments analogous to Mars.

  9. Effect of mineral particles containing iron on primary cultures of rabbit tracheal epithelial cells: possible implication of oxidative stress.

    PubMed Central

    Guilianelli, C; Baeza-Squiban, A; Boisvieux-Ulrich, E; Houcine, O; Zalma, R; Guennou, C; Pezerat, H; Marano, F

    1993-01-01

    Environmental mineral particles such as asbestos are responsible for numerous respiratory diseases. In addition to effects related to their geometry, particles are now assumed to act by triggering an oxidative stress process. Iron-containing particles, in particular, can produce oxygen-activated species by oxidizing their iron. To evaluate the involvement of iron-containing particles in respiratory diseases, three mineral particles (chrysotile, nemalite, and hematite) were tested in primary cultures of tracheal epithelium. Because of the ciliary beat, the three mineral particles were quickly concentrated at the periphery of the mucociliary epithelium, reconstituted in vitro where they induced cellular lesions. Endocytosis of the three types of particles was observed. Cytotoxicity studies have indicated that among the tested particles, the most cytostatic after 24 hr of treatment was the one that contained more Fe2+ available on the surface, nemalite. Moreover, the effect of nemalite was reduced by pretreatment with desferrioxamine. As mineral particles, especially asbestos, are suspected to induce squamous metaplasia, we chose to study two specific transformations of the epithelium: the expression of cytokeratin-13 and the formation of cross-linked envelopes. Under our culture conditions, nemalite and chrysotile increased the expression of the cytokeratin-13, a specific marker of squamous metaplasia, whereas nemalite was the only particle able to strongly induce the formation of cross-linked envelopes. Nemalite was the most cytostatic particle and the most efficient at inducing squamous metaplasia. Measures of oxidizing power by electron-spin resonance revealed that nemalite produced the most oxygen-activated species.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1. Figure 2. a Figure 2. b Figure 2. c Figure 2. d Figure 2. e Figure 2. f Figure 3. a Figure 3. b Figure 3. c Figure 3. d Figure 4. Figure 5. a Figure 5. b Figure 5. c Figure 5. d Figure 6. PMID:8119255

  10. Iron Oxide Nanoparticles: An Insight into their Biomedical Applications

    PubMed

    Couto, Diana; Freitas, Marisa; Carvalho, Félix; Fernandes, Eduarda

    2015-05-15

    Iron oxide nanoparticles (IONs) are among the most common types of nanoparticles (NPs) used in biomedical applications. IONs can be presented in different forms [e.g. magnetite (Fe3O4), hematite (α-Fe2O3) and maghemite (γ- Fe2O3)], and are usually coated with substances and/or polymers according to the purpose for which they are intended to be used. In recent years, IONs use has been increasing exponentially in many fields of biomedicine, namely in magnetic resonance imaging, cell sorting, tissue repair, induction of hyperthermia and drug delivery, among others. This review aims to provide an update on the different IONs and the substances and/or polymers that can be used to coat the IONs core as well as their applications and biological properties, namely their biodistribution in the human body and their cellular internalization pathways.

  11. Photocatalytic Iron Oxide Coatings Produced by Thermal Spraying Process

    NASA Astrophysics Data System (ADS)

    Navidpour, A. H.; Salehi, M.; Amirnasr, M.; Salimijazi, H. R.; Azarpour Siahkali, M.; Kalantari, Y.; Mohammadnezhad, M.

    2015-12-01

    Recently, hematite coatings with semiconductor properties have received attention for photocatalytic applications. In this study, plasma and flame spraying techniques were used for hematite deposition on 316 stainless steel plates. X-ray diffraction was used for phase composition analysis, and methylene blue was used as an organic pollutant to evaluate the photocatalytic activity of thermally sprayed coatings. The results showed that all these coatings could act under visible-light irradiation but the one deposited by flame spraying at 20 cm stand-off distance showed the highest photocatalytic activity. The results showed that wavelength of the light source and pH of the solution affected the photocatalytic activity significantly. It was also shown that thermally sprayed iron oxide coatings could have a high photo-absorption ability, which could positively affect the photocatalytic activity.

  12. Transformation of iron oxides on PI electrospun membranes

    NASA Astrophysics Data System (ADS)

    Li, Penggang; Lv, Fengzhu; Liu, Leipeng; Ding, Ling; Zhang, Yihe

    2016-09-01

    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-Fe2O3 loaded PI composite fibers were prepared by electrospinning of poly(amic acid) PAA solution followed by loading Fe3+ on the PAA membrane by ion-exchange and then imidization. Then the α-Fe2O3 on PI membrane were reduced by H2 to give magnetic PI membranes. The content of α-Fe2O3 and Fe3O4 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.

  13. Super paramagnetic iron oxide nanoparticle modified mancozeb imprinted polymer

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Madhuri, Rashmi; Sharma, Prashant K.

    2017-05-01

    An electrochemical sensor for detection of mancozeb from soil and vegetable sample using molecularly imprinted star polymer modified with iron oxide nanoparticles (SPIONs) is described in this work. We have prepared SPIONS by hydrothermal method and modified with vinyl silane to introduce double bond at their surface. The vinyl group modified SPIONs were used to form mancozeb imprinted star polymer (ISP). The ISPs have specific recognition ability high adsorption capacity towards their template molecule and could be easily extracted from complex matrices using a simple magnet. The prepared polymer was well characterized by field emissive scanning electron microscopy (FE-SEM). Under the optimum condition, the prepared sensor shows good response for mancozeb in the range of 5.96 to 222.39 µg L-1 (detection limit=0.98 µg L-1). The proposed sensors have highly selective for detection of mancozeb in soil and vegetable samples also.

  14. Genotoxicity of Superparamagnetic Iron Oxide Nanoparticles in Granulosa Cells

    PubMed Central

    Pöttler, Marina; Staicu, Andreas; Zaloga, Jan; Unterweger, Harald; Weigel, Bianca; Schreiber, Eveline; Hofmann, Simone; Wiest, Irmi; Jeschke, Udo; Alexiou, Christoph; Janko, Christina

    2015-01-01

    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. PMID:26540051

  15. System for recycling char in iron oxide reducing kilns

    SciTech Connect

    Baker, A.C.; Keran, V.P.

    1983-03-08

    A method and means for improving the efficiency of the process for directly reducing ore containing iron oxide in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the ore feed and discharge ends of the kiln, as both fuel and reductant, is disclosed wherein the charred coal or char found in the discharge product is recycled into the process at the discharge end of the kiln rather than the feed end as in the prior art. In particular, the recovered char, both coarse and finer particles, are transported to a recycle bin from which they are returned at a preselected rate to the kiln process by being injected along with the coal blown into the discharge end of the kiln. Alternatively, the recycle char alone may be fed without any coal at the discharge end of the kiln.

  16. Iron oxide nanoparticles stabilized inside highly ordered mesoporous silica

    NASA Astrophysics Data System (ADS)

    Bhaumik, A.; Samanta, S.; Mal, N. K.

    2005-11-01

    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 powder XRD, TEM, SEM/EDS, N_{2} adsorption, FT-IR and UV-visible spectroscopies. Characterization data indicated well-dispersed isolated nanoclusters of (Fe_{2}O_{3})_{n}, within the internal surface of 2D-hexagonal mesoporous silica structure. No occluded Fe/Fe_{2}O_{3} crystallites were observed at the external surface of the mesoporous silica nanocomposites. Inorganic mesoporous host, such as hydrophilic silica in the pore walls, directs a physical constraint necessary to prevent the creation of large Fe_{2}O_{3} agglomerates and enables the formation of nanosized Fe_{2}O_{3} particles inside the mesopore.

  17. On the Simultaneous Iron Oxide Reduction and Carburization Kinetics

    NASA Astrophysics Data System (ADS)

    D'Abreu, Jose Carlos; Kohler, Helio Marques; Falero, Edelink Efrain Tinoco; Otaviano, Mauricio Marcos

    Nowadays the most important Direct Reduction — DR processes in shaft furnaces has to deal with carbon fines precipitation and DRI carburization issues. Based in a cooperative research program joining Catholic University (PUC-Rio) and SAMARCO Mining Co, a project dealing with pellets reduction and those two phenomena was established. This work analyzes kinetically the three reactions mentioned before, considering typical values for the operational variables temperature, flowrate, pressure and gas composition, parameters commonly used to control the DRI formation in the Reduction Zone — RZ of the shaft furnaces. From laboratories experimental results, the kinetic equations for those reactions were established and, using the superposition principle, generated a specific global kinetic model for the iron oxide reduction and the soot formation. Finally, using those experimental results and applying a planned statistical factorial analysis for the experiments, the numerical coefficients for each equation were calculated and the correlation factor determined for the proposed global kinetic equation.

  18. Iron oxide nanoparticles in different modifications for antimicrobial phototherapy

    NASA Astrophysics Data System (ADS)

    Tuchina, Elena S.; Kozina, Kristina V.; Shelest, Nikita A.; Kochubey, Vyacheslav I.; Tuchin, Valery V.

    2014-03-01

    The main goal of this study was to investigate the sensitivity of microorganisms to combined action of blue light and iron oxide nanoparticles. Two strains of Staphylococcus aureus - methicillin-sensitive and meticillin-resistant were used. As a blue light source LED with spectral maximum at 405 nm was taken. The light exposure was ranged from 5 to 30 min. The Fe2O3 (diameter ˜27 nm), Fe3O4 nanoparticles (diameter ˜19 nm), and composite Fe2O3/TiO2 nanoparticles (diameter ˜100 nm) were synthesized. It was shown that irradiation by blue light caused from 20% to 88% decrease in the number of microorganisms treated with nanoparticles. Morphological changes in bacterial cells after phototreatment were analyzed using scanning electron microscope.

  19. Magnetic iron oxide nanoclusters with tunable optical response

    NASA Astrophysics Data System (ADS)

    Kostopoulou, Athanasia; Tsiaoussis, Ioannis; Lappas, Alexandros

    2011-04-01

    We have developed a modified synthetic protocol for the growth of monodispersed, superparamagnetic, flower-like colloidal nanoclusters (CNCs), which are consisted of smaller iron oxide nanocrystals with adjustable size. We show that their optical properties can be tuned by applying an external magnetic field. The latter controls the subtle balance of the CNCs’ mutual interactions (magnetic versus electrostatic) and drives their assembly in aqueous media. Spectrophotometric measurements reveal that a diffuse reflectance maximum, in the visible range, is related to the CNCs organization. As the strength of the external magnetic field increases, in the range 160-600 G, the spectral weight of this feature shifts towards the blue region of the spectrum. The induced photonic crystal-like response entails a remarkable magneto-optical behavior, closely associated with the size-dependent characteristics of the CNCs ensemble. Such materials pave the way for promising technological implementations in photonics.

  20. Magneto-optical Properties of Iron Oxide Nanoclusters

    NASA Astrophysics Data System (ADS)

    Kostopoulou, Athanasia; Tsiaoussis, Ioannis; Lappas, Alexandros

    2010-11-01

    We have developed a modified synthetic protocol for the growth of monodispersed, superparamagnetic, flower-like colloidal nanoclusters (CNCs) with 40-120 nm average diameters. Importantly, these are consisted of smaller iron oxide nanocrystals, also with adjustable size (12.2-7.7 nm). We show that their optical properties can be tuned by applying an external magnetic field. Spectrophotometric measurements under these conditions reveal a diffuse reflectance maximum in the visible range, which is related to the CNCs assembly in ordered structures. The increasing field strength leads to a blue shift in the spectral weight when the size of the CNCs is above a critical diameter. The size-dependent characteristics of the CNCs determine their magneto-optical behavior and their potential in photonic crystal based technologies.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Iron Oxide Nanoparticle Based Contrast Agents for Magnetic Resonance Imaging.

    PubMed

    Shen, Zheyu; Wu, Aiguo; Chen, Xiaoyuan

    2017-05-01

    Magnetic iron oxide nanoparticles (MIONs) have attracted enormous attention due to their wide applications, including for magnetic separation, for magnetic hyperthermia, and as contrast agents for magnetic resonance imaging (MRI). This review article introduces the methods of synthesizing MIONs, and their application as MRI contrast agents. Currently, many methods have been reported for the synthesis of MIONs. Herein, we only focus on the liquid-based synthesis methods including aqueous phase methods and organic phase methods. In addition, the MIONs larger than 10 nm can be used as negative contrast agents and the recently emerged extremely small MIONs (ES-MIONs) smaller than 5 nm are potential positive contrast agents. In this review, we focus on the ES-MIONs because ES-MIONs avoid the disadvantages of MION-based T2- and gadolinium chelate-based T1-weighted contrast agents.

  3. Water oxidation catalysis by birnessite@iron oxide core-shell nanocomposites.

    PubMed

    Elmaci, Gökhan; Frey, Carolin E; Kurz, Philipp; Zümreoğlu-Karan, Birgül

    2015-03-16

    In this work, magnetic nanocomposite particles were prepared for water oxidation reactions. The studied catalysts consist of maghemite (γ-Fe2O3), magnetite (Fe3O4), and manganese ferrite (MnFe2O4) nanoparticles as cores coated in situ with birnessite-type manganese oxide shells and were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, thermal, chemical, and surface analyses, and magnetic measurements. The particles were found to be of nearly spherical core-shell architectures with average diameter of 150 nm. Water oxidation catalysis was examined using Ce(4+) as the sacrificial oxidant. All core-shell particles were found to be active water oxidation catalysts. However, the activity was found to depend on a variety of factors like the type of iron oxide core, the structure and composition of the shell, the coating characteristics, and the surface properties. Catalysts containing magnetite and manganese ferrite as core materials displayed higher catalytic activities per manganese ion (2650 or 3150 mmolO2 molMn(-1) h(-1)) or per mass than nanoiron oxides (no activity) or birnessite alone (1850 mmolO2 molMn(-1) h(-1)). This indicates synergistic effects between the MnOx shell and the FeOx core of the composites and proves the potential of the presented core-shell approach for further catalyst optimization. Additionally, the FeOx cores of the particles allow magnetic recovery of the catalyst and might also be beneficial for applications in water-oxidizing anodes because the incorporation of iron might enhance the overall conductivity of the material.

  4. Mutagenic Effects of Iron Oxide Nanoparticles on Biological Cells.

    PubMed

    Dissanayake, Niluka M; Current, Kelley M; Obare, Sherine O

    2015-09-30

    In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism's ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the OPEN ACCESS Int. J. Mol. Sci. 2015, 16 23483 transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells.

  5. Mutagenic Effects of Iron Oxide Nanoparticles on Biological Cells

    PubMed Central

    Dissanayake, Niluka M.; Current, Kelley M.; Obare, Sherine O.

    2015-01-01

    In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism’s ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells. PMID:26437397

  6. Detoxification of H(2)S by differentiated colonic epithelial cells: implication of the sulfide oxidizing unit and of the cell respiratory capacity.

    PubMed

    Mimoun, Sabria; Andriamihaja, Mireille; Chaumontet, Catherine; Atanasiu, Calina; Benamouzig, Robert; Blouin, Jean Marc; Tomé, Daniel; Bouillaud, Frédéric; Blachier, François

    2012-07-01

    Sulfide is released in the large intestine lumen by the microbiota and is an inhibitor of mitochondrial respiration and a genotoxic agent in colonocytes when present in excess. Deciphering how colonocytes metabolize sulfide is an important issue. In this study, using the human colonic epithelial HT-29 Glc(-/+) cells, we found that 50 μM sodium hydrogen sulfide represents the threshold of concentration above which respiration is decreased. The capacity of HT-29 Glc(-/+) cells to oxidize lower concentration of sulfide was associated with the expression of transcripts corresponding to the enzymes of the sulfide oxidizing unit (SOU), that is, sulfide quinone reductase (SQR), dioxygenase ethylmalonic encephalopathy, and thiosulfate sulfur transferase (TST). Inhibition of cell O(2) consumption by sulfide was reverted by zinc but not by calcium and iron. When the cells undergo either spontaneous or butyrate-induced differentiation, their capacity to oxidize sulfide was significantly increased. The expression levels of the genes corresponding to the enzymes of the SOU were not increased, whereas increased cellular maximal respiratory capacity and oxygen consumption by the dioxygenase were both measured. In human biopsies recovered from various parts of the large intestine, the three enzymes of the SOU were expressed. SOU and cell respiratory capacity are crucial for sulfide detoxification in colonocytes. Sulfide oxidative capacity in the colonic mucosa is higher in differentiated than in proliferative epithelial cells. The cell respiratory capacity and SOU activity appear to represent major determinants allowing sulfide detoxification in colonic epithelial cells.

  7. The role of antioxidants and iron chelators in the treatment of oxidative stress in thalassemia.

    PubMed

    Fibach, Eitan; Rachmilewitz, Eliezer A

    2010-08-01

    On the basis of all the presented data, one can conclude that oxidative stress plays a major role in the pathophysiology of thalassemia and other congenital and acquired hemolytic anemias. Free extracellular (labile plasma iron, LPI) and intracellular (labile iron pool, LIP) iron species that have been identified in thalassemic blood cells are responsible for generation of oxidative stress by catalyzing formation of oxygen radicals over the antioxidant capacity of the cell. Consequently, there is a rationale for iron chelation to eliminate the free-iron species, which in this respect, act like antioxidants. In addition, antioxidants such as vitamin E and polyphenols are also capable of ameliorating increased oxidative stress parameters and, given together with iron chelators, may provide a substantial improvement in the pathophysiology of hemolytic anemias and particularly in thalassemia.

  8. Concurrent Dual Contrast for Cellular Magnetic Resonance Imaging Using Gadolinium Oxide and Iron Oxide Nanoparticles

    PubMed Central

    Loai, Yasir; Ganesh, Tameshwar; Margaret Cheng, Hai-Ling

    2012-01-01

    Rationale and Objectives. Concurrent visualization of differential targets in cellular and molecular imaging is valuable for resolving processes spatially and temporally, as in monitoring different cell subtypes. The purpose of this study was to demonstrate concurrent, dual (positive and negative) contrast visualization on magnetic resonance imaging (MRI) of two colocalized cell populations labeled with Gadolinium “Gd” oxide and iron “Fe” oxide nanoparticles. Materials and Methods. Human aortic endothelial cells (EC) and smooth muscle cells (SMC) were labeled with various concentrations of Gd oxide and Fe oxide, respectively. MRI on single- or mixed-cell samples was performed at 7 tesla. Proper cell phenotype expressions, cell uptake of contrast agents, and the effect of labeling on cell viability and proliferation were also determined. Results. Both contrast agents were efficiently taken up by cells, with viability and proliferation largely unaffected. On MRI, the positive contrast associated with Gd oxide-labeled EC and negative contrast associated with Fe oxide-labeled SMC discriminated the presence of each cell type, whether it existed alone or colocalized in a mixed-cell sample. Conclusion. It is feasible to use Gd oxide and Fe oxide for dual contrast and concurrent discrimination of two colocalized cell populations on MRI at 7 tesla. PMID:22919479

  9. Ferrous iron oxidation by Thiobacillus ferrooxidans: inhibition with benzoic acid, sorbic acid and sodium lauryl sulfate

    SciTech Connect

    Onysko, S.J.

    1984-07-01

    Acid mine drainage is formed by the weathering or oxidation of pyritic material exposed during coal mining. The rate of pyritic material oxidation can be greatly accelerated by certain acidophilic bacteria such as Thiobacillus ferrooxidans which catalyse the oxidation of ferrous to ferric iron. A number of organic compounds, under laboratory conditions, can apparently inhibit both the oxidation of ferrous to ferric iron by T. ferrooxidans and the weathering of pyritic material by mixed cultures of acid mine drainage micro-organisms. Sodium lauryl sulphate (SLS), an anionic surfactant has proved effective in this respect. Benzoic acid, sorbic acid and SLS at low concentrations, each effectively inhibited bacterial oxidation of ferrous iron in batch cultures of T. ferrooxidans. The rate of chemical oxidation of ferrous iron in low pH, sterile, batch reactors was not substantially affected at the tested concentrations of any of the compounds.

  10. Gold and iron oxide associations under supergene conditions: An experimental approach

    NASA Astrophysics Data System (ADS)

    Greffié, Catherine; Benedetti, Marc F.; Parron, Claude; Amouric, Marc

    1996-05-01

    Abstract-The interaction of gold hydroxo-chloro complexes with iron oxides (ferrihydrites, goethites) during coprecipitation experiments is investigated. Chemical analyses of solids and solutions are coupled with a detailed characterization of the iron oxides with various methods, including X-ray diffraction, High Resolution Transmission Electron Microscopy (HRTEM), and Mössbauer spectroscopy. HCl solutions containing varying amounts of AuCl 4- and ferric nitrate were titrated to neutral or alkaline pH, resulting in the coprecipitation of gold and iron oxide phases (ferrihydrite or goethite). Reference titrations were performed in the absence of iron. Most of the gold was removed from solution in the presence of iron oxides whereas gold remained dissolved in the reference samples. In association with iron oxides two forms of gold have been identified by HRTEM and 197Au Mössbauer spectroscopy: metallic gold as well as chloro and/or hydroxo combined gold. This combined gold is in a trivalent state as the primary product which means that a reduction process is not a necessary step for the adsorption of gold species on iron oxides. Metallic gold characterized in these products by means of HRTEM consists mainly of colloids ranging from 3-60 nm in diameter embedded in the ferrihydrite matrix, as isolated particles or as particles associated with goethite laths. The smallest metallic gold particles detected would be almost invisible to classical observation techniques used for solid phases. In our experiments, oxidation-reduction reactions between Fe 2+ and Au 3+ are responsible for the presence of metallic gold observed on the iron phases. Photochemical reactions may also take part in the reduction process. Colloidal gold and gold complexes could be associated to the iron oxides by strong electrostatic interactions. Our results suggest that poorly ordered iron oxides are highly efficient in trapping gold from solutions thanks to their high surface area, and favor gold

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

    NASA Astrophysics Data System (ADS)

    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

  12. Environmental Factors Affecting Ammonium Oxidation Under Iron Reducing Conditions

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed Central

    Naqvi, Saba; Samim, Mohammad; Abdin, MZ; Ahmed, Farhan Jalees; Maitra, AN; Prashant, CK; Dinda, Amit K

    2010-01-01

    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 induced by nanoparticles studied using the lactate dehydrogenase assay, showed both concentration- and time-dependent damage. Thus, this study concluded that use of a low optimum concentration of superparamagnetic iron oxide nanoparticles is important for avoidance of oxidative stress-induced cell injury and death. PMID:21187917

  14. Iron Oxide Nanoparticles as a Potential Iron Fertilizer for Peanut (Arachis hypogaea).

    PubMed

    Rui, Mengmeng; Ma, Chuanxin; Hao, Yi; Guo, Jing; Rui, Yukui; Tang, Xinlian; Zhao, Qi; Fan, Xing; Zhang, Zetian; Hou, Tianqi; Zhu, Siyuan

    2016-01-01

    Nanomaterials are used in practically every aspect of modern life, including agriculture. The aim of this study was to evaluate the effectiveness of iron oxide nanoparticles (Fe2O3 NPs) as a fertilizer to replace traditional Fe fertilizers, which have various shortcomings. The effects of the Fe2O3 NPs and a chelated-Fe fertilizer (ethylenediaminetetraacetic acid-Fe; EDTA-Fe) fertilizer on the growth and development of peanut (Arachis hypogaea), a crop that is very sensitive to Fe deficiency, were studied in a pot experiment. The results showed that Fe2O3 NPs increased root length, plant height, biomass, and SPAD values of peanut plants. The Fe2O3 NPs promoted the growth of peanut by regulating phytohormone contents and antioxidant enzyme activity. The Fe contents in peanut plants with Fe2O3 NPs and EDTA-Fe treatments were higher than the control group. We used energy dispersive X-ray spectroscopy (EDS) to quantitatively analyze Fe in the soil. Peanut is usually cultivated in sandy soil, which is readily leached of fertilizers. However, the Fe2O3 NPs adsorbed onto sandy soil and improved the availability of Fe to the plants. Together, these results show that Fe2O3 NPs can replace traditional Fe fertilizers in the cultivation of peanut plants. To the best of our knowledge, this is the first research on the Fe2O3 NPs as the iron fertilizer.

  15. Iron Oxide Nanoparticles as a Potential Iron Fertilizer for Peanut (Arachis hypogaea)

    PubMed Central

    Rui, Mengmeng; Ma, Chuanxin; Hao, Yi; Guo, Jing; Rui, Yukui; Tang, Xinlian; Zhao, Qi; Fan, Xing; Zhang, Zetian; Hou, Tianqi; Zhu, Siyuan

    2016-01-01

    Nanomaterials are used in practically every aspect of modern life, including agriculture. The aim of this study was to evaluate the effectiveness of iron oxide nanoparticles (Fe2O3 NPs) as a fertilizer to replace traditional Fe fertilizers, which have various shortcomings. The effects of the Fe2O3 NPs and a chelated-Fe fertilizer (ethylenediaminetetraacetic acid-Fe; EDTA-Fe) fertilizer on the growth and development of peanut (Arachis hypogaea), a crop that is very sensitive to Fe deficiency, were studied in a pot experiment. The results showed that Fe2O3 NPs increased root length, plant height, biomass, and SPAD values of peanut plants. The Fe2O3 NPs promoted the growth of peanut by regulating phytohormone contents and antioxidant enzyme activity. The Fe contents in peanut plants with Fe2O3 NPs and EDTA-Fe treatments were higher than the control group. We used energy dispersive X-ray spectroscopy (EDS) to quantitatively analyze Fe in the soil. Peanut is usually cultivated in sandy soil, which is readily leached of fertilizers. However, the Fe2O3 NPs adsorbed onto sandy soil and improved the availability of Fe to the plants. Together, these results show that Fe2O3 NPs can replace traditional Fe fertilizers in the cultivation of peanut plants. To the best of our knowledge, this is the first research on the Fe2O3 NPs as the iron fertilizer. PMID:27375665

  16. CARBON MONOXIDE REVERSIBLY DISRUPTS IRON HOMEOSTATIS AND RESPIRATORY EPITHELIAL CELLS FUNCTION

    EPA Science Inventory

    Iron dissociation from heme is a major factor in iron metabolism and cellular concentrations of the metal correlate inversely with the expression of heme oxygenase (HO). We tested the hypothesis that 1) exposure to a product of HO, carbon monoxide (CO), disturbs iron homeostas...

  17. CARBON MONOXIDE REVERSIBLY DISRUPTS IRON HOMEOSTATIS AND RESPIRATORY EPITHELIAL CELLS FUNCTION

    EPA Science Inventory

    Iron dissociation from heme is a major factor in iron metabolism and cellular concentrations of the metal correlate inversely with the expression of heme oxygenase (HO). We tested the hypothesis that 1) exposure to a product of HO, carbon monoxide (CO), disturbs iron homeostas...

  18. Iron and iron oxide nanoparticles obtained by ultra-short laser ablation in liquid

    NASA Astrophysics Data System (ADS)

    De Bonis, A.; Lovaglio, T.; Galasso, A.; Santagata, A.; Teghil, R.

    2015-10-01

    Laser ablation of an iron target in water and acetone has been carried out using a frequency doubled Nd:glass laser source (pulse duration of 250 fs and frequency repetition rate of 10 Hz). The observation of the nanostructures formed in the laser irradiated region of the metallic target and fast shadowgraphic analysis of the laser induced cavitation bubble have been performed in order to correlate the size distribution of the obtained nanoparticles to the dynamics of the ablation process. The composition, morphology and oxidation state of the synthesized nanoproducts have been investigated by XPS (X-ray Photoelectron Spectroscopy), TEM (Transmission Electron Microscopy) and microRaman spectroscopy. The experimental data support a relationship between the nanoparticles size distribution and the femtosecond laser ablation mechanism, while the chemical and structural characteristics of the nanoparticles can be tuned by varying the liquid medium.

  19. The Global Redox Responding RegB/RegA Signal Transduction System Regulates the Genes Involved in Ferrous Iron and Inorganic Sulfur Compound Oxidation of the Acidophilic Acidithiobacillus ferrooxidans.

    PubMed

    Moinier, Danielle; Byrne, Deborah; Amouric, Agnès; Bonnefoy, Violaine

    2017-01-01

    The chemical attack of ore by ferric iron and/or sulfuric acid releases valuable metals. The products of these reactions are recycled by iron and sulfur oxidizing microorganisms. These acidophilic chemolithotrophic prokaryotes, among which Acidithiobacillus ferrooxidans, grow at the expense of the energy released from the oxidation of ferrous iron and/or inorganic sulfur compounds (ISCs). In At. ferrooxidans, it has been shown that the expression of the genes encoding the proteins involved in these respiratory pathways is dependent on the electron donor and that the genes involved in iron oxidation are expressed before those responsible for ISCs oxidation when both iron and sulfur are present. Since the redox potential increases during iron oxidation but remains stable during sulfur oxidation, we have put forward the hypothesis that the global redox responding two components system RegB/RegA is involved in this regulation. To understand the mechanism of this system and its role in the regulation of the aerobic respiratory pathways in At. ferrooxidans, the binding of different forms of RegA (DNA binding domain, wild-type, unphosphorylated and phosphorylated-like forms of RegA) on the regulatory region of different genes/operons involved in ferrous iron and ISC oxidation has been analyzed. We have shown that the four RegA forms are able to bind specifically the upstream region of these genes. Interestingly, the phosphorylation of RegA did not change its affinity for its cognate DNA. The transcriptional start site of these genes/operons has been determined. In most cases, the RegA binding site(s) was (were) located upstream from the -35 (or -24) box suggesting that RegA does not interfere with the RNA polymerase binding. Based on the results presented in this report, the role of the RegB/RegA system in the regulation of the ferrous iron and ISC oxidation pathways in At. ferrooxidans is discussed.

  20. Respiratory cancer and air pollution from iron foundries in a Scottish town: an epidemiological and environmental study.

    PubMed Central

    Smith, G H; Williams, F L; Lloyd, O L

    1987-01-01

    A geographical association between respiratory cancer and air pollution from steel foundries has been shown previously in Scotland and elsewhere. In the present study the iron-founding town of Kirkintilloch was found to have standardised mortality ratios (SMRs) for respiratory cancer in 1959-63, 1964-8, and 1969-73 that were unexceptional in comparison with Scotland. Nevertheless, when SMRs were calculated for respiratory cancer for the period 1966-76 in five zones of the town arranged, a priori, according to probable exposure to fumes from two iron foundries, and in the individual enumeration districts of the 1971 census, higher SMRs were found in the residential areas most exposed to pollution from the foundries. The gradient of the zones' SMRs--high close to the foundries to low at some distance from them--persisted despite standardisation of the SMRs for social class. A survey of the concentrations of several metals in soil cores sampled at 51 sites throughout the town showed a pattern of pollution that probably illustrated the effects of prevailing winds and topography on the pollution plumes from the foundries. The value of sampling soil cores in investigations where historical sources of metallic air pollution are of epidemiological interest was emphasised by the detection of high concentrations of Ni in an area where a nickel refinery had been located many decades previously. PMID:3689714

  1. Polyubiquitin gene expression contributes to oxidative stress resistance in respiratory yeast (Saccharomyces cerevisiae).

    PubMed

    Cheng, L; Watt, R; Piper, P W

    1994-05-10

    UBI4, the polyubiquitin gene of Saccharomyces cerevisiae, is expressed at a low level in vegetative cells, yet induced strongly in response to starvation, cadmium, DNA-damaging agents and heat shock. UBI4 is also expressed at a higher basal level in cells growing by respiration as compared to glucose-repressed cells growing by fermentation. This higher UBI4 expression of respiratory cultures probably helps to counteract the greater oxidative stress of respiratory growth. The effects of inactivating UBI4 on high temperature viability are more marked with respiratory cultures. Also loss of UBI4 leads to a considerably increased rate of killing of respiring cells by hydrogen peroxide, whereas the same gene inactivation has relatively little effect on the peroxide sensitivity of cells in which mitochondrial functions are repressed. This is the first study to reveal that ubiquitin levels in cells can influence their ability to withstand oxidative stress.

  2. Advanced oxidation of natural organic matter using hydrogen peroxide and iron-coated pumice particles.

    PubMed

    Kitis, M; Kaplan, S S

    2007-08-01

    The oxidative removal of natural organic matter (NOM) from waters using hydrogen peroxide and iron-coated pumice particles as heterogeneous catalysts was investigated. Two NOM sources were tested: humic acid solution and a natural source water. Iron coated pumice removed about half of the dissolved organic carbon (DOC) concentration at a dose of 3000 mg l(-1) in 24 h by adsorption only. Original pumice and peroxide dosed together provided UV absorbance reductions as high as 49%, mainly due to the presence of metal oxides including Al(2)O(3), Fe(2)O(3) and TiO(2) in the natural pumice, which are known to catalyze the decomposition of peroxide forming strong oxidants. Coating the original pumice particles with iron oxides significantly enhanced the removal of NOM with peroxide. A strong linear correlation was found between iron contents of coated pumices and UV absorbance reductions. Peroxide consumption also correlated with UV absorbance reduction. Control experiments proved the effective coating and the stability of iron oxide species bound on pumice surfaces. Results overall indicated that in addition to adsorptive removal of NOM by metal oxides on pumice surfaces, surface reactions between iron oxides and peroxide result in the formation of strong oxidants, probably like hydroxyl radicals, which further oxidize both adsorbed NOM and remaining NOM in solution, similar to those in Fenton-like reactions.

  3. INCORPORATION OF LABELED NITRIC OXIDE INTO RESPIRATORY TRACT LINING FLUIDS AND BLOOD PLASMA DURING LUNG INFLAMMATION

    EPA Science Inventory

    Incorporation of labeled nitric oxide (N18O) into respiratory tract lining fluids and blood plasma during lung inflammation. Slade, R., Norwood, J., Crissman, K., McKee, J., Hatch, G. PTB, ETD, NHEERL, ORD, USEPA, Res. Tri. Pk., NC

    Our earlier studies have demonstrated t...

  4. INCORPORATION OF LABELED NITRIC OXIDE INTO RESPIRATORY TRACT LINING FLUIDS AND BLOOD PLASMA DURING LUNG INFLAMMATION

    EPA Science Inventory

    Incorporation of labeled nitric oxide (N18O) into respiratory tract lining fluids and blood plasma during lung inflammation. Slade, R., Norwood, J., Crissman, K., McKee, J., Hatch, G. PTB, ETD, NHEERL, ORD, USEPA, Res. Tri. Pk., NC

    Our earlier studies have demonstrated t...

  5. Rescuing hepatocytes from iron-catalyzed oxidative stress using vitamins B1 and B6.

    PubMed

    Mehta, Rhea; Dedina, Liana; O'Brien, Peter J

    2011-08-01

    In the following rescue experiments, iron-mediated hepatocyte oxidative stress cytotoxicity was found to be prevented if vitamin B1 or B6 was added 1h after treatment with iron. The role of iron in catalyzing Fenton-mediated oxidative damage has been implicated in iron overload genetic diseases, carcinogenesis (colon cancer), Alzheimer's disease and complications associated with the metabolic syndrome through the generation of reactive oxygen species (ROS). The objectives of this study were to interpret the cytotoxic mechanisms and intracellular targets of oxidative stress using "accelerated cytotoxicity mechanism screening" techniques (ACMS) and to evaluate the rescue strategies of vitamins B1 and B6. Significant cytoprotection by antioxidants or ROS scavengers indicated that iron-mediated cytotoxicity could be attributed to reactive oxygen species. Of the B6 vitamers, pyridoxal was best at rescuing hepatocytes from iron-catalyzed lipid peroxidation (LPO), protein oxidation, and DNA damage, while pyridoxamine manifested greatest protection against ROS-mediated damage. Thiamin (B1) decreased LPO, mitochondrial and protein damage and DNA oxidation. Together, these results indicate that added B1 and B6 vitamins protect against the multiple targets of iron-catalyzed oxidative damage in hepatocytes. This study provides insight into the search for multi-targeted natural therapies to slow or retard the progression of diseases associated with Fenton-mediated oxidative damage.

  6. Synthesis and characterization of hybrid materials containing iron oxide for removal of sulfides from water.

    PubMed

    Jacukowicz-Sobala, Irena; Wilk, Łukasz J; Drabent, Krzysztof; Kociołek-Balawejder, Elżbieta

    2015-12-15

    Hybrid materials containing iron oxides based on macroporous and gel-type sulfonic and carboxylic cation exchangers as supporting materials were obtained. Multiple factors, including the kind of functional groups, ion exchange capacity, and polymer matrix type (chemical constitution and porous structure), affected the amount of iron oxides introduced into their matrix (7.8-35.2% Fe). Products containing the highest iron content were obtained using carboxylic cation exchangers, with their inorganic deposit being mostly a mixture of iron(III) oxides, including maghemite. Obtained hybrid polymers were used for removal of sulfides from anoxic aqueous solutions (50-200mgS(2-)/dm(3)). The research showed that the form (Na(+) or H(+)) of ionic groups of hybrid materials had a crucial impact on the sulfide removal process. Due to high iron oxide content (35% Fe), advantageous chemical constitution and porous structure, the highest removal efficiency (60mgS(2-)/g) was exhibited by a hybrid polymer obtained using a macroporous carboxylic cation exchanger as the host material. The process of sulfide removal was very complex and proceeded with heterogeneous oxidation, iron(III) oxide reductive dissolution and formation of sulfide oxidation and precipitation products such as iron(II) sulfides, thiosulfates and polysulfides. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Application of Iron Oxide as a pH-dependent Indicator for Improving the Nutritional Quality

    PubMed Central

    2016-01-01

    Acid food indicators can be used as pH indicators for evaluating the quality and freshness of fermented products during the full course of distribution. Iron oxide particles are hardly suspended in water, but partially or completely agglomerated. The agglomeration degree of the iron oxide particles depends on the pH. The pH-dependent particle agglomeration or dispersion can be useful for monitoring the acidity of food. The zeta potential of iron oxide showed a decreasing trend as the pH increased from 2 to 8, while the point of zero charge (PZC) was observed around at pH 6.0-7.0. These results suggested that the size of the iron oxide particles was affected by the change in pH levels. As a result, the particle sizes of iron oxide were smaller at lower pH than at neutral pH. In addition, agglomeration of the iron oxide particles increased as the pH increased from 2 to 7. In the time-dependent aggregation test, the average particle size was 730.4 nm and 1,340.3 nm at pH 2 and 7, respectively. These properties of iron oxide particles can be used to develop an ideal acid indicator for food pH and to monitor food quality, besides a colorant or nutrient for nutrition enhancement and sensory promotion in food industry. PMID:27482521

  8. Observational evidence of crystalline iron oxides on Mars

    SciTech Connect

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

    1990-08-30

    Visible to near-IR (0.4-1.0 {mu}m) 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 = {lambda}/{Delta}{lambda} {approx} 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 {mu}m and 0.81-0.94 {mu}m both seen here clearly for the first time. These absorption features are interpreted as Fe{sup 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 {mu}m 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.

  9. Biocompatible capped iron oxide nanoparticles for Vibrio cholerae detection.

    PubMed

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

    2015-05-01

    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.

  10. Biocompatible capped iron oxide nanoparticles for Vibrio cholerae detection

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    We report the studies relating to fabrication of an efficient immunosensor for Vibrio cholerae detection. Magnetite (iron oxide (Fe3O4)) 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 Fe3O4 and CA-Fe3O4/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 Fe3O4, CA-Fe3O4 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 (Fe3O4) and 189.51 nm (CA-Fe3O4) by DLS measurement. The results of electrochemical response studies of the fabricated BSA/Ab/CA-Fe2O3/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.

  11. Modeling the kinetics of ferrous iron oxidation by monochloramine.

    PubMed

    Vikesland, Peter J; Valentine, Richard L

    2002-02-15

    The maintenance of disinfectants in distribution systems is necessary to ensure drinking water safety. Reactions with oxidizable species can however lead to undesirable disinfectant losses. Previous work has shown that the presence of Fe(II) can cause monochloramine loss in distribution system waters. This paper further examines these reactions and presents a reaction mechanism and kinetic model. The mechanism includes both aqueous-phase reactions and surface-catalyzed reactions involving the iron oxide product. In addition, it considers competitive reactions involving the amidogen radical that lead to a nonelementary stoichiometry. Using the method of initial rates, the aqueous-phase reactions were found to have first-order dependencies on Fe(II), NH2Cl, and OH- and a rate coefficient (kNH2Cl,soln) of 3.10 (+/-0.560) x 10(9) M(-2) min(-1). The surface-mediated reactions were modeled by assuming the formation of two surface species: >FeOFe+ and >FeOFeOH. Using numerical techniques, combined rate coefficients for the surface-mediated processes were determined to be 0.56 M(-3) min(-1) and 3.5 x 10(-18) M(-4) min(-1), respectively. The model was then used to examine monochloramine and Fe(II) stability under conditions similar to those observed in distribution systems. Our findings suggest the potential utility of monochloramine as an oxidant for Fe(III) removal in drinking water treatment.

  12. [Exhale nitric oxide (NO) and respiratory function measured with body plethysmography in children].

    PubMed

    Storme, L; Riou, Y; Leclerc, F; Dubois, A; Deschildre, A; Pierre, M H; Logier, R; Robin, H; Lequien, P

    1998-04-01

    Exhaled nitric oxide (NO) may be a marker of airway inflammation. Previous studies in adults have shown that the level of NO in exhaled air is influenced by several factors (breath holding, exercise, etc), or by several disease (asthma, congestive heart failure, diseases of the upper respiratory tract, cystic fibrosis, etc). However, few studies have been performed in children less than 3 years of age. The aim of this study was to determine endogenous NO levels in children with various diseases during lung volume measurements. Fifty-two children aged 18.3 +/- 9.5 months were studied. The population was divided in two groups, according to the underlying disease: a group of 39 children with cystic fibrosis (n = 7), bronchopulmonary dysplasia (n = 17), asthma (n = 7) or recurrent respiratory tract infections (n = 8) and a second group of 13 children without respiratory disease. Lung function was measured by whole body plethysmography and several respiratory parameters were calculated (functional residual capacity [FRC], compliance and resistances of the respiratory system, trapped volume). NO production was measured on a chemiluminescence analyzer from mixed exhaled air collected into a bag, over a period of 5 minutes. NO production was related to disease: exhaled NO levels were three times higher in bronchopulmonary dysplasia and cystic fibrosis, compared to NO levels in children without respiratory disease. They were higher in asthma. They were not altered in recurrent respiratory tract infections. No correlation was found between respiratory parameters and NO production. However, exhaled NO levels were correlated to trapped volume, which defined dynamic part of pulmonary hyperinflation. Levels of endogenous NO in infants were similar to those measured in adults with and without inflammatory respiratory disease. Lung distention influenced exhaled NO production.

  13. The complex interplay of iron metabolism, reactive oxygen species, and reactive nitrogen species: insights into the potential of various iron therapies to induce oxidative and nitrosative stress.

    PubMed

    Koskenkorva-Frank, Taija S; Weiss, Günter; Koppenol, Willem H; Burckhardt, Susanna

    2013-12-01

    Production of minute concentrations of superoxide (O2(*-)) and nitrogen monoxide (nitric oxide, NO*) plays important roles in several aspects of cellular signaling and metabolic regulation. However, in an inflammatory environment, the concentrations of these radicals can drastically increase and the antioxidant defenses may become overwhelmed. Thus, biological damage may occur owing to redox imbalance-a condition called oxidative and/or nitrosative stress. A complex interplay exists between iron metabolism, O2(*-), hydrogen peroxide (H2O2), and NO*. Iron is involved in both the formation and the scavenging of these species. Iron deficiency (anemia) (ID(A)) is associated with oxidative stress, but its role in the induction of nitrosative stress is largely unclear. Moreover, oral as well as intravenous (iv) iron preparations used for the treatment of ID(A) may also induce oxidative and/or nitrosative stress. Oral administration of ferrous salts may lead to high transferrin saturation levels and, thus, formation of non-transferrin-bound iron, a potentially toxic form of iron with a propensity to induce oxidative stress. One of the factors that determine the likelihood of oxidative and nitrosative stress induced upon administration of an iv iron complex is the amount of labile (or weakly-bound) iron present in the complex. Stable dextran-based iron complexes used for iv therapy, although they contain only negligible amounts of labile iron, can induce oxidative and/or nitrosative stress through so far unknown mechanisms. In this review, after summarizing the main features of iron metabolism and its complex interplay with O2(*-), H2O2, NO*, and other more reactive compounds derived from these species, the potential of various iron therapies to induce oxidative and nitrosative stress is discussed and possible underlying mechanisms are proposed. Understanding the mechanisms, by which various iron formulations may induce oxidative and nitrosative stress, will help us

  14. Effect of iron supplementation during lactation on maternal iron status and oxidative stress: A randomized controlled trial.

    PubMed

    Jorgensen, Josh M; Yang, Zhenyu; Lönnerdal, Bo; Chantry, Caroline J; Dewey, Kathryn G

    2017-10-01

    We examined the effect of iron-containing prenatal vitamin-mineral supplements taken postpartum on biomarkers of iron status and oxidative stress. Lactating women (n = 114) were randomly assigned to consume daily one iron-free prenatal vitamin-mineral supplement plus either 27 mg of iron or placebo for approximately 3.5 months. The placebo group took the tablets between meals, while those given iron took the tablets either with (Fe-W) or between meals (Fe-B). Blood and urine samples were collected before and after the supplementation period to analyze hemoglobin (Hb), ferritin, hepcidin, transferrin saturation (TfSat), total plasma iron, and biomarkers of oxidative stress (isoprostane and 8-hydroxy-2-deoxyguanosine (8-OHdG)) and inflammation (C-reactive protein (CRP) and alpha-1-acid glycoprotein (AGP)). There was a trend toward a greater change in Hb among women in the Fe-B group compared to placebo (+2.5 vs. -3.7 g/L, respectively, p = 0.063). When the iron groups were combined, there was a greater change in Hb (+1.4 g/L) compared to placebo (p = 0.010). There were trends toward greater changes in TfSat (p = 0.087) and total plasma iron (p = 0.065) in the iron groups compared to placebo, yet no significant differences between the three groups in change in hepcidin (p = 0.291), isoprostane (p = 0.319), or 8-OHdG (p = 0.659), nor in change in ferritin among those with elevated CRP at baseline (60% of women; p = 0.946); among those without elevated CRP (40% of women), ferritin increased more in the iron groups compared to placebo (p = 0.001). Iron consumption during lactation moderately increased iron status, particularly among women without elevated CRP, and increased Hb, but did not significantly increase oxidative stress. © 2016 John Wiley & Sons Ltd.

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

    PubMed Central

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

    2015-01-01

    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. PMID:25871933

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

    PubMed

    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 (<3 d, phase I) and 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.

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

    SciTech Connect

    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

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

    PubMed

    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.

  19. Synthesis of phase-pure and monodisperse iron oxide nanoparticles by thermal decomposition

    SciTech Connect

    Hufschmid, Ryan D.; Arami, Hamed; Ferguson, R. Matthew; Gonzales, Marcela; Teeman, Eric M.; Brush, Lucien N.; Browning, Nigel D.; Krishnan, Kannan M.

    2015-06-03

    We present a comprehensive template for the design and synthesis of iron oxide nanoparticles with control over size, size distribution, phase, and resulting properties. Monodisperse superparamagnetic iron oxide nanoparticles were synthesized by thermal decomposition of three different iron containing precursors (iron oleate, iron pentacarbonyl, and iron oxyhydroxide) in organic solvents under a variety of synthetic conditions. We compare the suitability of these three kinetically controlled synthesis protocols, which have in common the use of iron oleate as a starting precursor or reaction intermediate, for producing nanoparticles with specific size and magnetic properties. Monodisperse particles were produced over a tunable range of sizes from approximately 2-30 nm. Reaction parameters such as precursor concentration, addition of surfactant, temperature, ramp rate, and time were adjusted to kinetically control size and size-distribution. In particular, large quantities of excess surfactant (up to 25:1 molar ratio) alter reaction kinetics and result in larger particles with uniform size; however, there is often a trade-off between large particles and a narrow size distribution. Iron oxide phase is also critical for establishing magnetic properties. As an example, we show the importance of obtaining the required iron oxide phase for application to Magnetic Particle Imaging (MPI), and describe how phase purity can be controlled.

  20. Zinc inhibits oxidative stress-induced iron signaling and apoptosis in Caco-2 cells.

    PubMed

    Kilari, Sreenivasulu; Pullakhandam, Raghu; Nair, K Madhavan

    2010-04-01

    Studies in humans and animals have suggested negative interactions of iron and zinc during their intestinal absorption. Further, zinc seems to prevent iron-induced oxidative damage in rats, which was hypothesized to be through the modulation of the intracellular iron signaling pathway. The aim of this study was, therefore, to understand the effects of zinc on oxidant-induced iron signaling and cell death in human enterocyte-like Caco-2 cells. We demonstrate that zinc decreases glucose/glucose oxidase (H(2)O(2)-generating system)-induced iron uptake and inhibits iron-regulatory protein 1 activation and divalent metal ion transporter 1 expression. There was also a concomitant decrease in oxidant-induced intracellular labile iron and restoration of ferritin and metallothionein expression. Further, zinc enhanced the Bcl-2/Bax ratio and reduced caspase-3 activity, leading to inhibition of apoptosis. Interestingly, bathophenanthroline disulfonic acid, an extracellular iron chelator, emulated the effects of zinc except for the reduced ferritin levels. These results suggest that zinc inhibits apoptosis by reducing oxidant-induced iron signaling in Caco-2 cells.

  1. Biosynthesis of stable iron oxide nanoparticles in aqueous extracts of Hordeum vulgare and Rumex acetosa plants.

    PubMed

    Makarov, Valentin V; Makarova, Svetlana S; Love, Andrew J; Sinitsyna, Olga V; Dudnik, Anna O; Yaminsky, Igor V; Taliansky, Michael E; Kalinina, Natalia O

    2014-05-27

    We report the synthesis and characterization of amorphous iron oxide nanoparticles from iron salts in aqueous extracts of monocotyledonous (Hordeum vulgare) and dicotyledonous (Rumex acetosa) plants. The nanoparticles were characterized by TEM, absorbance spectroscopy, SAED, EELS, XPS, and DLS methods and were shown to contain mainly iron oxide and iron oxohydroxide. H. vulgare extracts produced amorphous iron oxide nanoparticles with diameters of up to 30 nm. These iron nanoparticles are intrinsically unstable and prone to aggregation; however, we rendered them stable in the long term by addition of 40 mM citrate buffer pH 3.0. In contrast, amorphous iron oxide nanoparticles (diameters of 10-40 nm) produced using R. acetosa extracts are highly stable. The total protein content and antioxidant capacity are similar for both extracts, but pH values differ (H. vulgare pH 5.8 vs R. acetosa pH 3.7). We suggest that the presence of organic acids (such oxalic or citric acids) plays an important role in the stabilization of iron nanoparticles, and that plants containing such constituents may be more efficacious for the green synthesis of iron nanoparticles.

  2. Calcium-Iron Oxide as Energy Storage Medium in Rechargeable Oxide Batteries

    DOE PAGES

    Berger, Cornelius M.; Mahmoud, Abdelfattah; Hermann, Raphaël P.; ...

    2016-08-08

    Rechargeable oxide batteries (ROB) comprise a regenerative solid oxide cell (rSOC) and a storage medium for oxygen ions. A sealed ROB avoids pumping loss, heat loss, and gas purity expenses in comparison with conventional rSOC. However, the iron oxide base storage medium degrades during charging–discharging cycles. In comparison, CaFe3O5 has improved cyclability and a high reversible oxygen storage capacity of 22.3 mol%. In this paper, we analyzed the redox mechanism of this compound. After a solid-state synthesis of CaFe3O5, we verified the phase composition and studied the redox reaction by means of X-ray diffraction, Mössbauer spectrometry, and scanning electron microscopy.more » Finally, results show a great potential to operate the battery with this storage material during multiple charging–discharging cycles.« less

  3. Calcium-Iron Oxide as Energy Storage Medium in Rechargeable Oxide Batteries

    SciTech Connect

    Berger, Cornelius M.; Mahmoud, Abdelfattah; Braun, Waldemar; Yazhenskikh, Elena; Sohn, Yoo Jung; Menzler, Norbert H.; Guillon, Olivier; Bram, Martin

    2016-08-08

    Rechargeable oxide batteries (ROB) comprise a regenerative solid oxide cell (rSOC) and a storage medium for oxygen ions. A sealed ROB avoids pumping loss, heat loss, and gas purity expenses in comparison with conventional rSOC. However, the iron oxide base storage medium degrades during charging–discharging cycles. In comparison, CaFe3O5 has improved cyclability and a high reversible oxygen storage capacity of 22.3 mol%. In this paper, we analyzed the redox mechanism of this compound. After a solid-state synthesis of CaFe3O5, we verified the phase composition and studied the redox reaction by means of X-ray diffraction, Mössbauer spectrometry, and scanning electron microscopy. Finally, results show a great potential to operate the battery with this storage material during multiple charging–discharging cycles.

  4. Calcium-Iron Oxide as Energy Storage Medium in Rechargeable Oxide Batteries

    SciTech Connect

    Berger, Cornelius M.; Mahmoud, Abdelfattah; Braun, Waldemar; Yazhenskikh, Elena; Sohn, Yoo Jung; Menzler, Norbert H.; Guillon, Olivier; Bram, Martin

    2016-08-08

    Rechargeable oxide batteries (ROB) comprise a regenerative solid oxide cell (rSOC) and a storage medium for oxygen ions. A sealed ROB avoids pumping loss, heat loss, and gas purity expenses in comparison with conventional rSOC. However, the iron oxide base storage medium degrades during charging–discharging cycles. In comparison, CaFe3O5 has improved cyclability and a high reversible oxygen storage capacity of 22.3 mol%. In this paper, we analyzed the redox mechanism of this compound. After a solid-state synthesis of CaFe3O5, we verified the phase composition and studied the redox reaction by means of X-ray diffraction, Mössbauer spectrometry, and scanning electron microscopy. Finally, results show a great potential to operate the battery with this storage material during multiple charging–discharging cycles.

  5. Mechanism of ferrous iron binding and oxidation by ferritin from a pennate diatom.

    PubMed

    Pfaffen, Stephanie; Abdulqadir, Raz; Le Brun, Nick E; Murphy, Michael E P

    2013-05-24

    A novel ferritin was recently found in Pseudo-nitzschia multiseries (PmFTN), a marine pennate diatom that plays a major role in global primary production and carbon sequestration into the deep ocean. Crystals of recombinant PmFTN were soaked in iron and zinc solutions, and the structures were solved to 1.65-2.2-Å resolution. Three distinct iron binding sites were identified as determined from anomalous dispersion data from aerobically grown ferrous soaked crystals. Sites A and B comprise the conserved ferroxidase active site, and site C forms a pathway leading toward the central cavity where iron storage occurs. In contrast, crystal structures derived from anaerobically grown and ferrous soaked crystals revealed only one ferrous iron in the active site occupying site A. In the presence of dioxygen, zinc is observed bound to all three sites. Iron oxidation experiments using stopped-flow absorbance spectroscopy revealed an extremely rapid phase corresponding to Fe(II) oxidation at the ferroxidase site, which is saturated after adding 48 ferrous iron to apo-PmFTN (two ferrous iron per subunit), and a much slower phase due to iron core formation. These results suggest an ordered stepwise binding of ferrous iron and dioxygen to the ferroxidase site in preparation for catalysis and a partial mobilization of iron from the site following oxidation.

  6. Influence of Fe(2+)-catalysed iron oxide recrystallization on metal cycling.

    PubMed

    Latta, Drew E; Gorski, Christopher A; Scherer, Michelle M

    2012-12-01

    Recent work has indicated that iron (oxyhydr-)oxides are capable of structurally incorporating and releasing metals and nutrients as a result of Fe2+-induced iron oxide recrystallization. In the present paper, we briefly review the current literature examining the mechanisms by which iron oxides recrystallize and summarize how recrystallization affects metal incorporation and release. We also provide new experimental evidence for the Fe2+-induced release of structural manganese from manganese-doped goethite. Currently, the exact mechanism(s) for Fe2+-induced recrystallization remain elusive, although they are likely to be both oxide-and metal-dependent. We conclude by discussing some future research directions for Fe2+-catalysed iron oxide recrystallization.

  7. Recent progress in magnetic iron oxide-semiconductor composite nanomaterials as promising photocatalysts

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Changzhong Jiang, Affc; Roy, Vellaisamy A. L.

    2014-11-01

    Photocatalytic degradation of toxic organic pollutants is a challenging tasks in ecological and environmental protection. Recent research shows that the magnetic iron oxide-semiconductor composite photocatalytic system can effectively break through the bottleneck of single-component semiconductor oxides with low activity under visible light and the challenging recycling of the photocatalyst from the final products. With high reactivity in visible light, magnetic iron oxide-semiconductors can be exploited as an important magnetic recovery photocatalyst (MRP) with a bright future. On this regard, various composite structures, the charge-transfer mechanism and outstanding properties of magnetic iron oxide-semiconductor composite nanomaterials are sketched. The latest synthesis methods and recent progress in the photocatalytic applications of magnetic iron oxide-semiconductor composite nanomaterials are reviewed. The problems and challenges still need to be resolved and development strategies are discussed.

  8. Recent progress in magnetic iron oxide-semiconductor composite nanomaterials as promising photocatalysts.

    PubMed

    Wu, Wei; Changzhong Jiang; Roy, Vellaisamy A L

    2015-01-07

    Photocatalytic degradation of toxic organic pollutants is a challenging tasks in ecological and environmental protection. Recent research shows that the magnetic iron oxide-semiconductor composite photocatalytic system can effectively break through the bottleneck of single-component semiconductor oxides with low activity under visible light and the challenging recycling of the photocatalyst from the final products. With high reactivity in visible light, magnetic iron oxide-semiconductors can be exploited as an important magnetic recovery photocatalyst (MRP) with a bright future. On this regard, various composite structures, the charge-transfer mechanism and outstanding properties of magnetic iron oxide-semiconductor composite nanomaterials are sketched. The latest synthesis methods and recent progress in the photocatalytic applications of magnetic iron oxide-semiconductor composite nanomaterials are reviewed. The problems and challenges still need to be resolved and development strategies are discussed.

  9. Gold catalysts supported on nanosized iron oxide for low-temperature oxidation of carbon monoxide and formaldehyde

    NASA Astrophysics Data System (ADS)

    Tang, Zheng; Zhang, Weidong; Li, Yi; Huang, Zuming; Guo, Huishan; Wu, Feng; Li, Jinjun

    2016-02-01

    This study aimed to optimize synthesis of gold catalyst supported on nanosized iron oxide and to evaluate the activity in oxidation of carbon monoxide and formaldehyde. Nanosized iron oxide was prepared from a colloidal dispersion of hydrous iron oxide through a dispersion-precipitation method. Gold was adsorbed onto nanosized iron oxide under self-generated basic conditions. Characterization results indicate that the iron oxide consisted of hematite/maghemite composite with primary particle sizes of 6-8 nm. Gold was highly dispersed on the surface of the support. The catalysts showed good activity in the oxidation of airborne carbon monoxide and formaldehyde. The optimal pH for their synthesis was ∼7. The catalytic performance could be enhanced by extending the adsorption time of gold species on the support within 21 h. The optimized catalyst was capable of achieving complete oxidation of 1% carbon monoxide at -20 °C and 33% conversion of 450 ppm formaldehyde at ambient temperature. The catalyst may be applicable to indoor air purification.

  10. The electrokinetic properties of colloidal magnetic iron oxides.

    PubMed

    Metcalfe, I M; Healy, T W

    2012-05-22

    A novel electrokinetic streaming potential technique has been used to determine the ζ potential behavior of three magnetic iron oxides, (Fe(3)O(4), γ-Fe(2)O(3), and CoFe(2)O(4)) as a function of pH and salt concentration. These colloidal materials, (nanosize in one dimension), are held in the form of a plug by means of external magnets. The streaming potential (E) is measured as a function of fluid flow induced by a pressure drop (ΔP) across the plug. The magnetically held plug is found to obey the requirements of the streaming potential technique; in each case an iso-electric point, (iep) independent of salt concentration is observed. However, if one uses the appropriate quantities in the standard formula, the calculated ζ potentials are very much lower than for oxides such as silica, alumina or goethite and other colloidal oxide, latex, etc. particulates in aqueous salt solutions. Furthermore, at a given pH, the measured ζ potentials anomalously increase in magnitude rather than decrease as observed conventionally as the salt concentration is increased. This apparent anomalous behavior could not be eliminated by incorporating surface conductance effects. However by including a conductance pathway, independent of pH or salt concentration, through the magnetic particle network itself, the anomaly was removed. Confirmation of the role of a conductance pathway through the magnetic particle network was obtained by using silica coated magnetic particles which displayed normal electrokinetic behavior. Finally, we have redesigned the plug-electrode assembly to allow measurement of streaming current, a technique know to eliminate contributions from plug network conductances of any kind. The resulting ζ potentials, derived from this streaming current technique are normal.

  11. Iron(II) Initiation of Lipid and Protein Oxidation in Pork: The Role of Oxymyoglobin.

    PubMed

    Zhou, Feibai; Jongberg, Sisse; Zhao, Mouming; Sun, Weizheng; Skibsted, Leif H

    2016-06-08

    Iron(II), added as FeSO4·7H2O, was found to increase the rate of oxygen depletion as detected electrochemically in a pork homogenate from Longissimus dorsi through an initial increase in metmyoglobin formation from oxymyoglobin and followed by formation of primary and secondary lipid oxidation products and protein oxidation as detected as thiol depletion in myofibrillar proteins. Without added iron(II), under the same conditions at 37 °C, oxygen consumption corresponded solely to the slow oxymyoglobin autoxidation. Long-lived myofibrillar protein radicals as detected by ESR spectroscopy in the presence of iron(II) were formed subsequently to oxymyoglobin oxidation, and their level was increased by lipid oxidation when oxygen was completely depleted. Similarly, the time profile for formation of lipid peroxide indicated that oxymyoglobin oxidation initiates both protein oxidation and lipid oxidation.

  12. Decaking of coal or oil shale during pyrolysis in the presence of iron oxides

    DOEpatents

    Rashid Khan, M.

    1988-05-05

    A method for producing a fuel from the pyrolysis of coal or oil shale in the presence of iron oxide in an inert gas atmosphere is described. The method includes the steps of pulverizing feed coal or oil shale, pulverizing iron oxide, mixing the pulverized feed and iron oxide, and heating the mixture in a gas atmosphere which is substantially inert to the mixture so as to form a product fuel, which may be gaseous, liquid and/or solid. The method of the invention reduces the swelling of coals, such as bituminous coal and the like, which are otherwise known to swell during pyrolysis. 4 figs., 8 tabs.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Decaking of coal or oil shale during pyrolysis in the presence of iron oxides

    DOEpatents

    Khan, M. Rashid

    1989-01-01

    A method for producing a fuel from the pyrolysis of coal or oil shale in the presence of iron oxide in an inert gas atmosphere. The method includes the steps of pulverizing feed coal or oil shale, pulverizing iron oxide, mixing the pulverized feed and iron oxide, and heating the mixture in a gas atmosphere which is substantially inert to the mixture so as to form a product fuel, which may be gaseous, liquid and/or solid. The method of the invention reduces the swelling of coals, such as bituminous coal and the like, which are otherwise known to swell during pyrolysis.

  15. Mitochondrial respiratory chain dysfunction variably increases oxidant stress in Caenorhabditis elegans.

    PubMed

    Dingley, Stephen; Polyak, Erzsebet; Lightfoot, Richard; Ostrovsky, Julian; Rao, Meera; Greco, Todd; Ischiropoulos, Harry; Falk, Marni J

    2010-03-01

    Mitochondrial dysfunction and associated oxidant stress have been linked with numerous complex diseases and aging largely by in vitro determination of mitochondria oxidant production and scavenging. We applied targeted in vivo fluorescence analyses of mitochondria-dense pharyngeal tissue in Caenorhabditis elegans to better understand relative mitochondrial effects, particularly on matrix oxidant burden, of respiratory chain complex, MnSOD, and insulin receptor mutants displaying variable longevity. The data demonstrate significantly elevated in vivo matrix oxidant burden in the short-lived complex I mutant, gas-1(fc21), which was associated with limited superoxide scavenging capacity despite robust MnSOD induction, as well as decreased mitochondria content and membrane potential. Significantly increased MnSOD activity was associated with in vivo matrix oxidant levels similar to wild-type in the long-lived respiratory chain complex III mutant, isp-1(qm150). Yet, despite greater superoxide scavenging capacity in the complex III mutant than in the significantly longer-lived insulin receptor mutant, daf-2(e1368), only the former showed modest oxidative stress sensitivity. Furthermore, increased longevity was seen in MnSOD knockout mutants (sod-2(ok1030) and sod-2(gk257)) that had decreased MnSOD scavenging capacity and increased in vivo matrix oxidant burden. Thus, factors beside oxidant stress must underlie RC mutant longevity in C. elegans. This work highlights the utility of the C. elegans model as a tractable means to non-invasively monitor multi-dimensional in vivo consequences of primary mitochondrial dysfunction.

  16. Physiochemical, mineralogical, and isotopic characterization of magnetite-rich iron oxides formed by thermophilic iron-reducing bacteria

    SciTech Connect

    Zhang, Chuanlun; Liu, Shi; Phelps, T.J.; Elless, M.

    1997-11-01

    Thermophilic (45-75{degrees}C) iron-reducing bacteria obtained from two sedimentary basins in Virginia and Colorado, USA, reduced amorphous Fe(III) oxyhydroxide to form magnetite-rich (>60% in most samples) iron oxides in acetate- or H{sub 2}/CO{sub 2}-enriched cultures. The mineralogical compositions of the iron oxides were determined by X-ray diffraction and oxidation state analyses. Significantly lower Eh values (< -300 mV) occurred in the enrichment cultures than in the abiotic controls (Eh > -100 mV). The pH values in acetate-enriched cultures did not change significantly from the starting value siderite was formed in addition to magnetite. The microbial production of magnetic and siderite was consistent, on a thermodynamic basis, with Eh-pH conditions determined for these experiments. Examination of the magnetite-rich iron oxides by scanning electron microscopy showed extracellular aggregates of <200 nm and no distinguishable increase in particle size over a period of 20 days. Average values of oxygen isotope fractionation between the magnetite-rich iron oxides (io) and water (wt), expressed as 10{sup 3} ln {alpha}{sub io-wt}, ranged from -0.09% at 50{degrees}C to -1.08{per_thousand} at 70{degrees}C. These values did not differ significantly among various cultures of different growth rates, suggesting that a kinetic isotopic effect is either unimportant or reproducible during microbial magnetic formation. Results of this research indicate that studies combining microbial activity, solution chemistry, mineralogy, and oxygen isotopes can provide insight into the environmental conditions and mechanisms for biogenic iron mineral formation in natural systems. 62 refs., 6 figs., 3 tabs.

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    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.

  19. [Inflammation and oxidative stress in respiratory and limb muscles of patients with severe sepsis].

    PubMed

    Pascual-Guardia, Sergio; Árbol, Francisca; Sánchez, Esther; Casadevall, Carme; Merlo, Victoria; Gea, Joaquim; Barreiro, Esther

    2013-09-07

    Oxidative stress and inflammation contribute to the diaphragm contractile dysfunction observed in animal models of sepsis and endotoxemia. In septic patients, molecular events have never been explored in their respiratory muscles. Levels of oxidative stress and inflammation were evaluated in a respiratory muscle, the external intercostal, and a limb muscle, the vastus lateralis, of patients with sepsis. Levels of oxidized and nitrated proteins, protein adducts of malondialdehyde and hydroxinonenal, antioxidant enzymes catalase and Mn-superoxide dismutase, tumor necrosis factor (TNF)-α, TNF-α receptors i and ii, interleukin (IL)-1 and IL-6, the panleukocyte marker CD18, and fiber type composition were explored using immunoblotting, real time-polymerase chain reaction, and immunohistochemistry in the external intercostal and vastus lateralis of patients with severe sepsis and/or septic shock. Compared to the controls, in septic patients, levels of oxidized and nitrated proteins were increased in the vastus lateralis, but not in the external intercostal, while those of the antioxidant enzymes did not differ, and the proportions and sizes of the muscle fibers were not significantly different in any muscle between patients and controls. Differences in activity between the respiratory and limb muscles may account for the differential pattern of oxidative stress and inflammation observed among patients with severe sepsis. These findings may have relevant implications for the clinical and therapeutic management of these patients. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  20. The 24-h carbohydrate oxidation rate in a human respiratory chamber predicts ad libitum food intake.

    PubMed

    Pannacciulli, Nicola; Salbe, Arline D; Ortega, Emilio; Venti, Colleen A; Bogardus, Clifton; Krakoff, Jonathan

    2007-09-01

    The 24-h respiratory quotient (24-h RQ) and 24-h carbohydrate balance (24-h CHO-Bal) are predictors of weight change. Whether these relations are mediated by the effects of substrate oxidation and balance on food intake is not known. We tested whether substrate oxidation and balance predict future ad libitum food intake. Substrate oxidation and balance were measured in a respiratory chamber in 112 normoglycemic subjects (83 Pima Indians and 29 whites; 67 men and 45 women) in energy balance for 3 d before tests were performed. The subjects then self-selected their food ad libitum for the following 3 d. The 24-h RQ, 24-h carbohydrate oxidation (24-h CHO-Ox), and 24-h CHO-Bal in the respiratory chamber predicted subsequent ad libitum food intake over 3 d (as a percentage of weight maintenance energy needs; %EN-WM). The 24-h CHO-Ox explained 15% of the variance in %EN-WM. The weight change over the 3-d ad libitum period was associated positively with 24-h CHO-Ox and negatively with 24-h CHO-Bal in the chamber; these associations were no longer significant after adjustment for %EN-WM. Carbohydrate oxidation and balance predict subsequent ad libitum food intake and can influence short-term weight changes, which indicates that carbohydrate balance is a contributing metabolic factor affecting food intake.

  1. Rare earth element partitioning between hydrous ferric oxides and acid mine water during iron oxidation

    USGS Publications Warehouse

    Verplanck, P.L.; Nordstrom, D.K.; Taylor, H.E.; Kimball, B.A.

    2004-01-01

    Ferrous iron rapidly oxidizes to Fe (III) and precipitates as hydrous Fe (III) oxides in acid mine waters. This study examines the effect of Fe precipitation on the rare earth element (REE) geochemistry of acid mine waters to determine the pH range over which REEs behave conservatively and the range over which attenuation and fractionation occur. Two field studies were designed to investigate REE attenuation during Fe oxidation in acidic, alpine surface waters. To complement these field studies, a suite of six acid mine waters with a pH range from 1.6 to 6.1 were collected and allowed to oxidize in the laboratory at ambient conditions to determine the partitioning of REEs during Fe oxidation and precipitation. Results from field experiments document that even with substantial Fe oxidation, the REEs remain dissolved in acid, sulfate waters with pH below 5.1. Between pH 5.1 and 6.6 the REEs partitioned to the solid phases in the water column, and heavy REEs were preferentially removed compared to light REEs. Laboratory experiments corroborated field data with the most solid-phase partitioning occurring in the waters with the highest pH. ?? 2004 Elsevier Ltd. All rights reserved.

  2. Sorption of two aromatic acids onto iron oxides: experimental study and modeling.

    PubMed

    Hanna, K

    2007-05-15

    The transport of aromatic carboxylate compounds in the environment can be strongly influenced by adsorption onto certain minerals, such as iron oxides and hydroxides, found in ground water and soils. Batch experiments with five iron oxides were conducted to quantify the contributions to adsorption from different iron mineral surfaces and compare adsorption characteristics of selected organic acids (gentisic acid (GA) and 1-hydroxy-2-naphthoic acid (HNA)). Because of their widespread abundance in soils and sediments, goethite, lepidocrocite, ferrihydrite, hematite, and magnetite were investigated. Sorption of two organic acids onto iron oxides was examined over a wide range of conditions (pH, ionic strength, and sorbate concentration). Specific surface area and mineral surface charge proved be important for the adsorption of these compounds. The sorption isotherm was described well by the Tempkin equation for both organic acids, with the adsorption constant higher for HNA than GA. For modeling the sorption edges of ferrihydrite and hematite, surface reactions involving the formation of mononuclear (1:1) surface species were proposed. These results indicate that the generalized two-layer model, with the assumption of homogeneous surface sites, could predict sorption on iron oxides over a range of pH conditions. The results of this study suggest that the mineralogy of the iron oxides and the pH value should be considered when predicting sorption of aromatic acids onto iron oxides and their fate in the soil and the environment.

  3. Oxidation and competitive retention of arsenic between iron- and manganese oxides

    NASA Astrophysics Data System (ADS)

    Ying, Samantha C.; Kocar, Benjamin D.; Fendorf, Scott

    2012-11-01

    Manganese (Mn) and iron (Fe) oxides are ubiquitous solids in terrestrial systems that have high sorptive capacities for many trace metals, including arsenic (As). Although numerous studies have characterized the effects of As adsorption onto Fe and Mn oxides individually, the fate of arsenic within mixed systems representative of natural environments has not been completely resolved. Here, we examine oxidation and competitive retention of As on goethite and birnessite using a Donnan reactor, where each oxide is isolated by a semi-permeable membrane through which arsenic can migrate. To initiate the Donnan reactor experiments, As(III) was simultaneously added to both chambers. Arsenic(III) injected into the birnessite chamber is rapidly oxidized to As(V) and then slowly redistributes across both chambers, while that added to the goethite chamber undergoes rapid adsorption; the adsorbed As(III) on goethite subsequently undergoes desorption and diffusion into the birnessite chamber followed by oxidation to As(V). With increased reaction time, As(V) is generated and preferentially partitioned onto goethite due to higher adsorption affinity compared to birnessite. Furthermore, the dissolved concentration of As(V) is controlled by the adsorption capacity of the goethite surface, which when saturated, leads to increased aqueous As concentrations; despite an increase in As(V) loading on birnessite with increasing initial As(III) concentration, the resulting aqueous As(V) concentration increase appreciably once the goethite surface is saturated. Our findings show that Mn oxides in soils act as a temporary sorbent of As, but operate primarily as strong oxidants responsible for transformation of As(III) to As(V), which can then strongly adsorb on the surrounding Fe oxide matrix.

  4. TRP Channels in Respiratory Pathophysiology: The Role of Oxidative, Chemical Irritant and Temperature Stimuli

    PubMed Central

    Zholos, Alexander V.

    2015-01-01

    There is rapidly growing evidence indicating multiple and important roles of Ca2+-permeable cation TRP channels in the airways, both under normal and disease conditions. The aim of this review was to summarize the current knowledge of TRP channels in sensing oxidative, chemical irritant and temperature stimuli by discussing expression and function of several TRP channels in relevant cell types within the respiratory tract, ranging from sensory neurons to airway smooth muscle and epithelial cells. Several of these channels, such as TRPM2, TRPM8, TRPA1 and TRPV1, are discussed in much detail to show that they perform diverse, and often overlapping or contributory, roles in airway hyperreactivity, inflammation, asthma, chronic obstructive pulmonary disease and other respiratory disorders. These include TRPM2 involvement in the disruption of the bronchial epithelial tight junctions during oxidative stress, important roles of TRPA1 and TRPV1 channels in airway inflammation, hyperresponsiveness, chronic cough, and hyperplasia of airway smooth muscles, as well as TRPM8 role in COPD and mucus hypersecretion. Thus, there is increasing evidence that TRP channels not only function as an integral part of the important endogenous protective mechanisms of the respiratory tract capable of detecting and ensuring proper physiological responses to various oxidative, chemical irritant and temperature stimuli, but that altered expression, activation and regulation of these channels may also contribute to the pathogenesis of respiratory diseases. PMID:26411771

  5. Hawaiian submarine manganese-iron oxide crusts - A dating tool?

    USGS Publications Warehouse

    Moore, J.G.; Clague, D.A.

    2004-01-01

    Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from post-depositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest-i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae

  6. Nitric oxide: a greenhouse gas is used in the treatment of respiratory failure.

    PubMed

    Supkis, D E; Graber, M

    2000-09-01

    Medical science has long made the improbable probable, saving lives and improving quality of life. Upon the introduction of medical devices that can deliver safe quantities of the poisonous gas nitric oxide to help patients with respiratory and other illnesses, the FDA requested ASTM Committee F29 on Anesthetic and Respiratory Equipment to provide standards for these devices. Dr. Daniel Supkis and Mark Graber explain the delicate process of delivering NO to patients and how ASTM standards now in development will increase the safety of this procedure.

  7. For Better or Worse, Iron Overload by Superparamagnetic Iron Oxide Nanoparticles as a MRI Contrast Agent for Chronic Liver Diseases.

    PubMed

    Zhou, Qibing; Wei, Yushuang

    2017-01-17

    Superparamagnetic iron oxide nanoparticles (SPIONs) have recently been used as an effective magnetic resonance imaging (MRI) contrast agent for the noninvasive diagnosis of chronic liver diseases including nonalcohol fatty liver diseases, nonalcohol steatohepatitis, and cirrhosis as well as liver tumors. However, the potential risk of the iron overload by SPIONs has been highly underestimated in chronic liver diseases. While most of SPIONs have been shown safe in the healthy group, significant toxicity potential by the iron overload has been revealed through immunotoxicity, lipid peroxidation, and fatty acid and cholesterol metabolism in cirrhosis as a high risk factor. As a result, the systems toxicology assessments of SPIONs are crucial in both healthy ones and chronic liver disease models to determine the margin of safety. In addition, the challenge of the iron overload by SPIONs requires better designed SPIONs as MRI contrast agents for chronic liver diseases such as the biodegradable nanocluster assembly with urine clearance.

  8. METABOLIC CAPACITY REGULATES IRON HOMEOSTATIS IN ENDOTHELIAL CELLS

    EPA Science Inventory

    The sensitivity of endothelial cells to oxidative stress and the high concentrations of iron in mitochondria led us to test the hypotheses that (1) changes in respiratory capacity alter iron homeostasis, and (2) lack of aerobic metabolism decreases labile iron stores and attenuat...

  9. METABOLIC CAPACITY REGULATES IRON HOMEOSTATIS IN ENDOTHELIAL CELLS

    EPA Science Inventory

    The sensitivity of endothelial cells to oxidative stress and the high concentrations of iron in mitochondria led us to test the hypotheses that (1) changes in respiratory capacity alter iron homeostasis, and (2) lack of aerobic metabolism decreases labile iron stores and attenuat...

  10. Effect of diquat-induced oxidative stress on iron metabolism in male Fischer-344 rats.

    PubMed

    Higuchi, Masashi; Yoshikawa, Yasunaga; Orino, Koichi; Watanabe, Kiyotaka

    2011-12-01

    Diquat toxicity causes iron-mediated oxidative stress; however, it remains unclear how diquat affects iron metabolism. Here, we examined the effect of diquat-induced oxidative stress on iron metabolism in male Fischer-344 rats, with particular focus on gene expression. Hepatic nonheme iron content was unchanged until 20 h after diquat treatment. Hepatic free iron levels increased markedly in the early stages following treatment and remained elevated for at least 6 h, resulting in severe hepatotoxicity, until returning to control levels at 20 h. The level of hepatic ferritin, especially the H-subunit, increased 20 h after diquat treatment due to elevated hepatic ferritin-H mRNA expression. These results indicate that early elevated levels of free iron in the liver of diquat-treated rats cause hepatotoxicity, and that this free iron is subsequently sequestered by ferritin synthesized under conditions of oxidative stress, thus limiting the pro-oxidant challenge of iron. The plasma iron concentration decreased at 6 and 20 h after diquat treatment, whereas the level of plasma interleukin-6 increased markedly at 3 h and remained high until 20 h. In the liver of diquat-treated rats, expression of hepcidin mRNA was markedly upregulated at 3 and 6 h, whereas ferroportin mRNA expression was downregulated slightly at 20 h. Transferrin receptor 1 mRNA expression was significantly upregulated at 3, 6, and 20 h. These results indicate that inhibition of iron release from iron-storage tissues, through stimulation of the interleukin-6-hepcidin-ferroportin axis, and enhanced iron uptake into hepatocytes, mediated by transferrin receptor 1, cause hypoferremia.

  11. Ligand-Enhanced Abiotic Iron Oxidation and the Effects of Chemical versus Biological Iron Cycling in Anoxic Environments

    PubMed Central

    2013-01-01

    This study introduces a newly isolated, genetically tractable bacterium (Pseudogulbenkiania sp. strain MAI-1) and explores the extent to which its nitrate-dependent iron-oxidation activity is directly biologically catalyzed. Specifically, we focused on the role of iron chelating ligands in promoting chemical oxidation of Fe(II) by nitrite under anoxic conditions. Strong organic ligands such as nitrilotriacetate and citrate can substantially enhance chemical oxidation of Fe(II) by nitrite at circumneutral pH. We show that strain MAI-1 exhibits unambiguous biological Fe(II) oxidation despite a significant contribution (∼30–35%) from ligand-enhanced chemical oxidation. Our work with the model denitrifying strain Paracoccus denitrificans further shows that ligand-enhanced chemical oxidation of Fe(II) by microbially produced nitrite can be an important general side effect of biological denitrification. Our assessment of reaction rates derived from literature reports of anaerobic Fe(II) oxidation, both chemical and biological, highlights the potential competition and likely co-occurrence of chemical Fe(II) oxidation (mediated by microbial production of nitrite) and truly biological Fe(II) oxidation. PMID:23402562

  12. Biomedical properties and preparation of iron oxide-dextran nanostructures by MAPLE technique

    PubMed Central

    2012-01-01

    Background In this work the chemical structure of dextran-iron oxide thin films was reported. The films were obtained by MAPLE technique from composite targets containing 10 wt. % dextran with 1 and 5 wt.% iron oxide nanoparticles (IONPs). The IONPs were synthesized by co-precipitation method. A KrF* excimer laser source (λ = 248 nm, τFWHM≅25 ns, ν = 10 Hz) was used for the growth of the hybrid, iron oxide NPs-dextran thin films. Results Dextran coated iron oxide nanoparticles thin films were indexed into the spinel cubic lattice with a lattice parameter of 8.36 Å. The particle sized calculated was estimated at around 7.7 nm. The XPS shows that the binding energy of the Fe 2p3/2 of two thin films of dextran coated iron oxide is consistent with Fe3+ oxides. The atomic percentage of the C, O and Fe are 66.71, 32.76 and 0.53 for the films deposited from composite targets containing 1 wt.% maghemite and 64.36, 33.92 and 1.72 respectively for the films deposited from composite targets containing 5 wt.% maghemite. In the case of cells cultivated on dextran coated 5% maghemite γ-Fe2O3, the number of cells and the level of F-actin were lower compared to the other two types of thin films and control. Conclusions The dextran-iron oxide continuous thin films obtained by MAPLE technique from composite targets containing 10 wt.% dextran as well as 1 and 5 wt.% iron oxide nanoparticles synthesized by co-precipitation method presented granular surface morphology. Our data proved a good viability of Hep G2 cells grown on dextran coated maghemite thin films. Also, no changes in cells morphology were noticed under phase contrast microscopy. The data strongly suggest the potential use of iron oxide-dextran nanocomposites as a potential marker for biomedical applications. PMID:22410001

  13. Cysteine-mediated reductive dissolution of poorly crystalline iron(III) oxides by Geobacter sulfurreducens.

    PubMed

    Doong, Ruey-An; Schink, Bernhard

    2002-07-01

    The reductive dissolution of poorly crystalline ferric oxides in the presence of cysteine was investigated to evaluate the potential of cysteine as a possible electron carrier to stimulate the reduction of iron(III) oxides by Geobacter sulfurreducens. The extent and rate of biotic and abiotic reduction of iron(III) oxides in the presence of cysteine at various concentrations were compared. Iron(III) oxides were reduced abiotically by cysteine. The initial rate and extent of iron(III) oxide reduction were correlated linearly with the cysteine concentration ranging from 0 to 6 mM. Also, addition of 0.5-2 mM cysteine significantly stimulated the rate and the extent of iron(III) oxide reduction in cultures of G. sulfurreducens. The cysteine concentration decreased in accordance with the increase of Fe(II) concentration and reached a nearly constant residual concentration. Cysteine depletion followed first-order kinetics and increased linearly with the cysteine concentration. An 8- to 11-fold increase in the extent of iron(III) oxide reduction relative to the abiotic system was observed. Comparison of sorbed and dissolved Fe(II) concentrations between cultures amended with cysteine and with other organic chelators showed that solubilization is not the main factor in cysteine-stimulated Fe(III) reduction. Addition of cystine could enhanced the extent of iron(III) oxide reduction, concomitant with the increase of the regenerated cysteine concentration and support the hypothesis that cysteine could serve as an electron carrier to transfer electrons from G. sulfurreducens to poorly crystalline iron(III) oxides.

  14. Spectroscopic investigation and direct comparison of the reactivities of iron pyridyl oxidation catalysts

    NASA Astrophysics Data System (ADS)

    Song, Yang; Mayes, Howard G.; Queensen, Matthew J.; Bauer, Eike B.; Dupureur, Cynthia M.

    2017-03-01

    The growing interest in green chemistry has fueled attention to the development and characterization of effective iron complex oxidation catalysts. A number of iron complexes are known to catalyze the oxidation of organic substrates utilizing peroxides as the oxidant. Their development is complicated by a lack of direct comparison of the reactivities of the iron complexes. To begin to correlate reactivity with structural elements, we compare the reactivities of a series of iron pyridyl complexes toward a single dye substrate, malachite green (MG), for which colorless oxidation products are established. Complexes with tetradentate, nitrogen-based ligands with cis open coordination sites were found to be the most reactive. While some complexes reflect sensitivity to different peroxides, others are similarly reactive with either H2O2 or tBuOOH, which suggests some mechanistic distinctions. [Fe(S,S-PDP)(CH3CN)2](SbF6)2 and [Fe(OTf)2(tpa)] transition under the oxidative reaction conditions to a single intermediate at a rate that exceeds dye degradation (PDP = bis(pyridin-2-ylmethyl) bipyrrolidine; tpa = tris(2-pyridylmethyl)amine). For the less reactive [Fe(OTf)2(dpa)] (dpa = dipicolylamine), this reaction occurs on a timescale similar to that of MG oxidation. Thus, the spectroscopic method presented herein provides information about the efficiency and mechanism of iron catalyzed oxidation reactions as well as about potential oxidative catalyst decomposition and chemical changes of the catalyst before or during the oxidation reaction.

  15. Spectroscopic investigation and direct comparison of the reactivities of iron pyridyl oxidation catalysts.

    PubMed

    Song, Yang; Mayes, Howard G; Queensen, Matthew J; Bauer, Eike B; Dupureur, Cynthia M

    2017-03-05

    The growing interest in green chemistry has fueled attention to the development and characterization of effective iron complex oxidation catalysts. A number of iron complexes are known to catalyze the oxidation of organic substrates utilizing peroxides as the oxidant. Their development is complicated by a lack of direct comparison of the reactivities of the iron complexes. To begin to correlate reactivity with structural elements, we compare the reactivities of a series of iron pyridyl complexes toward a single dye substrate, malachite green (MG), for which