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

Science.gov (United States)

Sayed, Farheen N; Polshettiwar, Vivek

2015-05-05

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

Structural characterization of hog iron oxide content glasses obtained from zinc hydrometallurgy wastes

International Nuclear Information System (INIS)

Romero, M.; Rincon, J.M.; Musik, S.; Kozhujharov, W.

1997-01-01

It has been carried out the structural characterization of high oxide content glasses obtained by melting of a goethite industrial waste from the zinc hydrometallurgy with other raw materials as dolomite and glass cullet. The structural characterization has been carried out by X-ray Diffraction (XRD), X-Ray Diffraction by Amorphous Dispersion (RDF) and Mossbauer spectroscopy. It has been determined the interatomic distance, the oxidation state and the coordination of iron atoms in these glasses. (Author) 16 refs

Superparamagnetic iron oxides for MRI

International Nuclear Information System (INIS)

Weissleder, R.; Reimer, P.

1993-01-01

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

Superparamagnetic iron oxides for MRI

Energy Technology Data Exchange (ETDEWEB)

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

1993-06-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-03-15

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

Accelerated dissolution of iron oxides in ice

Directory of Open Access Journals (Sweden)

D. Jeong

2012-11-01

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

Iron Abundances in Lunar Impact Basin Melt Sheets From Orbital Magnetic Field Data

Science.gov (United States)

Oliveira, Joana S.; Wieczorek, Mark A.; Kletetschka, Gunther

2017-12-01

Magnetic field data acquired from orbit shows that the Moon possesses many magnetic anomalies. Though most of these are not associated with known geologic structures, some are found within large impact basins within the interior peak ring. The primary magnetic carrier in lunar rocks is metallic iron, but indigenous lunar rocks are metal poor and cannot account easily for the observed field strengths. The projectiles that formed the largest impact basins must have contained a significant quantity of metallic iron, and a portion of this iron would have been retained on the Moon's surface within the impact melt sheet. Here we use orbital magnetic field data to invert for the magnetization within large impact basins using the assumption that the crust is unidirectionally magnetized. We develop a technique based on laboratory thermoremanent magnetization acquisition to quantify the relationship between the strength of the magnetic field at the time the rock cooled and the abundance of metal in the rock. If we assume that the magnetized portion of the impact melt sheet is 1 km thick, we find average abundances of metallic iron ranging from 0.11% to 0.45 wt %, with an uncertainty of a factor of about 3. This abundance is consistent with the metallic iron abundances in sampled lunar impact melts and the abundance of projectile contamination in terrestrial impact melts. These results help constrain the composition of the projectile, the impact process, and the time evolution of the lunar dynamo.

Melting of Grey Cast Iron Based on Steel Scrap Using Silicon Carbide

Directory of Open Access Journals (Sweden)

Stojczew A.

2014-08-01

Full Text Available The paper presents the issue of synthetic cast iron production in the electric induction furnace exclusively on the steel scrap base. Silicon carbide and synthetic graphite were used as carburizers. The carburizers were introduced with solid charge or added on the liquid metal surface. The chemical analysis of the produced cast iron, the carburization efficiency and microstructure features were presented in the paper. It was stated that ferrosilicon can be replaced by silicon carbide during the synthetic cast iron melting process. However, due to its chemical composition (30% C and 70% Si which causes significant silicon content in iron increase, the carbon deficit can be partly compensated by the carburizer introduction. Moreover it was shown that the best carbon and silicon assimilation rate is obtained where the silicon carbide is being introduced together with solid charge. When it is thrown onto liquid alloy surface the efficiency of the process is almost two times less and the melting process lasts dozen minutes long. The microstructure of the cast iron produced with the silicon carbide shows more bulky graphite flakes than inside the microstructure of cast iron produced on the pig iron base.

Oxidation effects during corium melt in-vessel retention

Energy Technology Data Exchange (ETDEWEB)

Almyashev, V.I.; Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Sulatsky, A.A.; Vitol, S.A. [Alexandrov Scientific-Research Institute of Technology (NITI), Sosnovy Bor (Russian Federation); Gusarov, V.V. [Ioffe Institute, St. Petersburg (Russian Federation); Bechta, S. [Royal Institute of Technology (KHT), Stockholm (Sweden); Barrachin, M.; Fichot, F. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), St Paul lez Durance (France); Bottomley, P.D., E-mail: paul.bottomley@ec.europa.eu [Joint Research Centre, Institut für Transurane (ITU), Karlsruhe (Germany); Fischer, M. [AREVA GmbH, Erlangen (Germany); Piluso, P. [CEA Cadarache-DEN/DTN/STRI (France)

2016-08-15

Highlights: • Corium–steel interaction tests were re-examined particularly for transient processes. • Oxidation of corium melt was sensitive to oxidant supply and surface characteristics. • Consequences for vessel steel corrosion rates in severe accidents were discussed. - Abstract: In the in-vessel corium retention studies conducted on the Rasplav-3 test facility within the ISTC METCOR-P project and OECD MASCA program, experiments were made to investigate transient processes taking place during the oxidation of prototypic molten corium. Qualitative and quantitative data have been produced on the sensitivity of melt oxidation rate to the type of oxidant, melt composition, molten pool surface characteristics. The oxidation rate is a governing factor for additional heat generation and hydrogen release; also for the time of secondary inversion of oxidic and metallic layers of corium molten pool.

Iron, Oxidative Stress and Gestational Diabetes

Directory of Open Access Journals (Sweden)

Taifeng Zhuang

2014-09-01

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

Glasses Containing Iron (II, III) Oxides For Immobilization Of Radioactive Technetium

International Nuclear Information System (INIS)

Kruger, A.A.; Heo, J.; Xu, K.; Choi, J.K.; Hrma, P.R.; Um, W.

2011-01-01

Technetium-99 (Tc-99) has posed serious environmental threats as US Department of Energy's high-level waste. This work reports the vitrification of Re, as surrogate for Tc-99, by iron-borosilicate and iron-phosphate glasses, respectively. Iron-phosphate glasses can dissolve Re as high as ∼ 1.2 wt. %, which can become candidate waste forms for Tc-99 disposal, while borosilicate glasses can retain less than 0.1 wt. % of Re due to high melting temperature and long melting duration. Vitrification of Re as Tc-99's mimic was investigated using iron-borosilicate and iron-phosphate glasses. The retention of Re in borosilicate glasses was less than 0.1 wt. % and more than 99 wt. % of Re were volatilized due to high melting temperature and long melting duration. Because the retention of Re in iron-phosphate glasses is as high as 1.2 wt. % and the volatilization is reduced down to ∼50 wt. %, iron-phosphate glasses can be one of the glass waste form candidates for Tc (or Re) disposal. The investigations of chemical durability and leaching test of iron-phosphate glasses containing Re are now underway to test the performance of the waste form.

Ferroxidase-Mediated Iron Oxide Biomineralization

DEFF Research Database (Denmark)

Zeth, Kornelius; Hoiczyk, Egbert; Okuda, Mitsuhiro

2016-01-01

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

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

International Nuclear Information System (INIS)

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

1978-01-01

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

21 CFR 73.3125 - Iron oxides.

Science.gov (United States)

2010-04-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-07-29

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

Carbon-Supported Iron Oxide Particles

DEFF Research Database (Denmark)

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

1996-01-01

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

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

International Nuclear Information System (INIS)

Mozaffari, M.; Amighian

2002-01-01

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

Mechanical properties of melt-derived erbium oxide

International Nuclear Information System (INIS)

Neuman, A.D.; Blacic, M.J.; Platero, M.; Romero, R.S.; McClellan, K.J.; Petrovic, J.J.

1998-01-01

Erbium oxide (Er 2 O 3 ) is a rare earth oxide that is chemically and thermally stable and has a melting point of 2,430 C. There is relatively little information available regarding single crystal growth of erbia or the properties of erbia. In this study, erbia single crystals have been grown in a Xenon Optical Floating Zone Unit (XeOFZ) capable of melting materials at temperatures up to 3,000 C. Erbia was melt synthesized in the XeOFZ unit in a container less fashion, proving for little chance of contamination. Crystals were grown in compressed air and in reducing atmospheres. A recurring problem with melt synthesis of erbia is the appearance of flakes at the edges of the melt zone during growth; these flakes disrupt the growth process. The processing details and an initial survey of the physical properties of erbia single crystals is discussed

Core-shell iron-iron oxide nanoparticles

DEFF Research Database (Denmark)

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

2004-01-01

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

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

Science.gov (United States)

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

2016-11-01

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

IRON REDOX EQUILIBRIUM AND DIFFUSIVITY IN MIXED ALKALI-ALKALINE EARTH-SILICA GLASS MELTS

Directory of Open Access Journals (Sweden)

KI-DONG KIM

2011-03-01

Full Text Available Dependence of redox behavior and diffusivity of iron on temperature and composition was studied in mixed alkali-alkaline earth-silica glass melts by means of square wave voltammetry (SWV. The voltammograms showed that irrespective of K2O/(Na2O+K2O the peak potential due to Fe3+/Fe2+ moved toward negative direction with temperature decrease and the peak current showed a strong dependence on frequency at constant temperature. Iron diffusion coefficient versus melt viscosity showed a good linearity. The compositional dependence showed that the peak potential shifted to the positive direction with increase of K2O but a typical mixed alkali effect occurred in iron diffusion either at constant temperature or at constant viscosity.

When Density Functional Approximations Meet Iron Oxides.

Science.gov (United States)

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

2016-10-11

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

Iron oxide surfaces

Science.gov (United States)

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

21 CFR 73.1200 - Synthetic iron oxide.

Science.gov (United States)

2010-04-01

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

21 CFR 73.200 - Synthetic iron oxide.

Science.gov (United States)

2010-04-01

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

The melting curve of iron to 250 gigapascals - A constraint on the temperature at earth's center

Science.gov (United States)

Williams, Quentin; Jeanloz, Raymond; Bass, Jay; Svendsen, Bob; Ahrens, Thomas J.

1987-01-01

The melting curve of iron, the primary constituent of earth's core, has been measured to pressures of 250 gigapascals with a combination of static and dynamic techniques. The melting temperature of iron at the pressure of the core-mantle boundary (136 GPa) is 4800 + or - 200 K, whereas at the inner core-outer core boundary (330 GPa), it is 7600 + or - 500 K. A melting temperature for iron-rich alloy of 6600 K at the inner core-outer core boundary and a maximum temperature of 6900 K at earth's center are inferred. This latter value is the first experimental upper bound on the temperature at earth's center, and these results imply that the temperature of the lower mantle is significantly less than that of the outer core.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-10-15

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

A deposit model for magmatic iron-titanium-oxide deposits related to Proterozoic massif anorthosite plutonic suites

Science.gov (United States)

Woodruff, Laurel G.; Nicholson, Suzanne W.; Fey, David L.

2013-01-01

This descriptive model for magmatic iron-titanium-oxide (Fe-Ti-oxide) deposits hosted by Proterozoic age massif-type anorthosite and related rock types presents their geological, mineralogical, geochemical, and geoenvironmental attributes. Although these Proterozoic rocks are found worldwide, the majority of known deposits are found within exposed rocks of the Grenville Province, stretching from southwestern United States through eastern Canada; its extension into Norway is termed the Rogaland Anorthosite Province. This type of Fe-Ti-oxide deposit dominated by ilmenite rarely contains more than 300 million tons of ore, with between 10- to 45-percent titanium dioxide (TiO2), 32- to 45-percent iron oxide (FeO), and less than 0.2-percent vanadium (V). The origin of these typically discordant ore deposits remains as enigmatic as the magmatic evolution of their host rocks. The deposits clearly have a magmatic origin, hosted by an age-constrained unique suite of rocks that likely are the consequence of a particular combination of tectonic circumstances, rather than any a priori temporal control. Principal ore minerals are ilmenite and hemo-ilmenite (ilmenite with extensive hematite exsolution lamellae); occurrences of titanomagnetite, magnetite, and apatite that are related to this deposit type are currently of less economic importance. Ore-mineral paragenesis is somewhat obscured by complicated solid solution and oxidation behavior within the Fe-Ti-oxide system. Anorthosite suites hosting these deposits require an extensive history of voluminous plagioclase crystallization to develop plagioclase-melt diapirs with entrained Fe-Ti-rich melt rising from the base of the lithosphere to mid- and upper-crustal levels. Timing and style of oxide mineralization are related to magmatic and dynamic evolution of these diapiric systems and to development and movement of oxide cumulates and related melts. Active mines have developed large open pits with extensive waste-rock piles, but

The structural role and homogeneous redox equilibria of iron in peraluminous, metaluminous and peralkaline silicate melts

Science.gov (United States)

Dickenson, M. P.; Hess, P. C.

1986-02-01

The compositional dependence of the redox ratio (FeO/FeO1.5) has been experimentally determined in K2O-Al2O3-SiO2-Fe2O3-FeO (KASFF) and K2O-CaO-Al2O3-SiO2-Fe2O3-FeO (KCASFF) silicate melts. Compositions were equilibrated at 1,450° C in air, with 78 mol % SiO2. KASFF melts have from 1 to 5 mol % Fe2O3 and include both peraluminous (K2OAl2O3) compositions. KCASFF melts have 1 mol % Fe2O3 encompassing peraluminous, metaluminous (CaO+K2O>Al2O3) and peralkaline compositions. Peralkaline KASFF melts with 1 mol % Fe2O3 have low and constant values for the redox ratio, whereas in peraluminous melts the redox ratio increases with increasing (K2O/Al2O3). Increasing total iron concentration increases the redox ratio in peraluminous melts and slightly decreases the redox ratio in peralkaline melts. Substituting CaO for K2O at fixed total iron (1 mol %) increases the redox ratio in both peraluminous and metaluminous KCASFF melts; however, the redox ratio in peralkaline KCASFF melts is not affected by this exchange. These data indicate that Fe3+ is in four-fold coordination, with K+ or Ca2+ providing local charge balance. The tetrahedral ferric species is most stable in peralkaline melts and least stable in peraluminous melts, due to the competition between Al3+ and Fe3+ for charge balancing cations in the latter melt. Tetrahedral Fe3+ is also less stable when Ca2+ provides local charge balance. The data are consistent with a network modifying role for Fe2+ in the melt. The data are interpreted to reflect the effects of melt composition on the partitioning of K+ and Ca2+ and Fe3+ and Al3+ between various species in the melt. These relationships are discussed in terms of homogeneous equilibria between various iron-bearing and iron-free melt species. The results also reflect the effect of liquid composition on the exchange potentials μFe3+ Al-1 and μCa0.5K-1. The exchange potentials are relatively constant in peralkaline melts, but decrease in metaluminous and peraluminous

Exploring Microbial Iron Oxidation in Wetland Soils

Science.gov (United States)

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

2009-04-01

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

Bio-inspired Iron Catalysts for Hydrocarbon Oxidations

Energy Technology Data Exchange (ETDEWEB)

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

2016-03-22

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

Prereduction and melting of domestic titaniferous materials

Science.gov (United States)

Nafziger, R. H.; Jordan, R. R.

1983-03-01

Two domestic ilmenites and one titaniferous magnetite were prereduced by the United States Department of the Interior, Bureau of Mines, in a batch rotary kiln with coal char to assess the feasibility of this technique in improving melting operations and subsequent electric furnace processing. All three prereduced titaniferous materials were melted satisfactorily in an electric arc furnace to produce iron as a metal suitable for further refining to steel; metallizations ranging from 63 to 83 pct of the iron oxides were achieved. The ilmenites yielded titanium enriched slags that were amenable to further processing by conventional methods. Prereduction decreased electrode consumption during furnace operation and also conserved expensive electrical energy that otherwise must be used to reduce and melt totally the entire titaniferous materials charge.

Amorphous structure of iron oxide of bacterial origin

Energy Technology Data Exchange (ETDEWEB)

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

2012-12-14

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

Application of the iron-enriched basalt waste form for immobilizing commercial transuranic waste

International Nuclear Information System (INIS)

Owen, D.E.

1981-08-01

The principal sources of commercial transuranic (TRU) waste in the United States are identified. The physical and chemical nature of the wastes from these sources are discussed. The fabrication technique and properties of iron-enriched basalt, a rock-like waste form developed for immobilizing defense TRU wastes, are discussed. The application of iron-enriched basalt to commercial TRU wastes is discussed. Review of commercial TRU wastes from mixed-oxide fuel fabrication, light water reactor fuel reprocessing, and miscellaneous medical, research, and industrial sources, indicates that iron-enriched basalt is suitable for most types of commercial TRU wastes. Noncombustible TRU wastes are dissolved in the high temperature, oxidizing iron-enriched basalt melt. Combustible TRU wastes are immobilized in iron-enriched basalt by incinerating the wastes and adding the TRU-bearing ash to the melt. Casting and controlled cooling of the melt produces a devitrified, rock-like iron-enriched basalt monolith. Recommendations are given for testing the applicability of iron-enriched basalt to commercial TRU wastes

Diffusion of hydrogen in iron oxides

International Nuclear Information System (INIS)

Bruzzoni, P.

1993-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1980-02-21

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

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

Science.gov (United States)

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

2015-01-06

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

Kinetics of iron redox reaction in silicate melts: A high temperature Xanes study on an alkali basalt

Energy Technology Data Exchange (ETDEWEB)

Cochain, B; Neuville, D R; Roux, J; Strukelj, E; Richet, P [Physique des Mineraux et Magmas, Geochimie-Cosmochimie, CNRS-IPGP, 4 place Jussieu, 75005 Paris (France); Ligny, D de [Universite Claude Bernard Lyon 1, LPCML, F-69622 Villeurbanne (France); Baudelet, F, E-mail: cochain@ipgp.jussieu.f [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin (France)

2009-11-15

In Earth and Materials sciences, iron is the most important transition element. Glass and melt properties are strongly affected by iron content and redox state with the consequence that some properties (i.e. viscosity, heat capacity, crystallization...) depend not only on the amounts of Fe{sup 2+} and Fe{sup 3+}, but also on the coordination state of these ions. In this work we investigate iron redox reactions through XANES experiments at the K-edge of iron. Using a high-temperature heating device, pre-edge of XANES spectra exhibits definite advantages to make in-situ measurements and to determine the evolution of redox state with time, temperature and composition of synthetic silicate melts. In this study, new kinetics measurements are presented for a basalt melt from the 31,000-BC eruption of the Puy de Lemptegy Volcano in France. These measurements have been made between 773 K and at superliquidus temperatures up to 1923 K.

Kinetics of iron redox reaction in silicate melts: A high temperature Xanes study on an alkali basalt

International Nuclear Information System (INIS)

Cochain, B; Neuville, D R; Roux, J; Strukelj, E; Richet, P; Ligny, D de; Baudelet, F

2009-01-01

In Earth and Materials sciences, iron is the most important transition element. Glass and melt properties are strongly affected by iron content and redox state with the consequence that some properties (i.e. viscosity, heat capacity, crystallization...) depend not only on the amounts of Fe 2+ and Fe 3+ , but also on the coordination state of these ions. In this work we investigate iron redox reactions through XANES experiments at the K-edge of iron. Using a high-temperature heating device, pre-edge of XANES spectra exhibits definite advantages to make in-situ measurements and to determine the evolution of redox state with time, temperature and composition of synthetic silicate melts. In this study, new kinetics measurements are presented for a basalt melt from the 31,000-BC eruption of the Puy de Lemptegy Volcano in France. These measurements have been made between 773 K and at superliquidus temperatures up to 1923 K.

Calculation of melting points of oxides

International Nuclear Information System (INIS)

Bobkova, O.S.; Voskobojnikov, V.G.; Kozin, A.I.

1975-01-01

The correlation between the melting point and thermodynamic parameters characterizing the strength of oxides and compounds is given. Such thermodynamic paramters include the energy and antropy of atomization

Steam explosions of molten iron oxide drops: easier initiation at small pressurizations

International Nuclear Information System (INIS)

Nelson, L.S.; Duda, P.M.

1982-01-01

Steam explosions caused by hot molten materials contacting liquid water following a possible light water nuclear reactor core overheat have been investigated by releasing single drops of a core melt simulant, molten iron oxide, into liquid water. Small steam explosions were triggered shortly afterwards by applying a pressure pulse to the water. The threshold peak pulse level above which an explosion always occurs was studied at ambient pressures between 0.083 and 1.12 MPa. It was found that the threshold decreased to a minimum in the range 0.2 - 0.8 MPa and then increased again. The effect of easier initiation as ambient pressure increases may have an important role in the triggering and propagation of a large scale steam explosion through a coarsely premixed dispersion of melt in water. (U.K.)

Metal ion binding to iron oxides

Science.gov (United States)

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

2006-06-01

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

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

DEFF Research Database (Denmark)

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

2002-01-01

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

Kinetics and mechanisms of iron redox reactions in silicate melts: The effects of temperature and alkali cations

Energy Technology Data Exchange (ETDEWEB)

Magnien, V.; Pinet, O. [CEA VALRHO, SCDV/LEBV, F-30207 Bagnols Sur Ceze, (France); Magnien, V.; Neuville, D. R.; Roux, J.; Richet, P. [IPGP, CNRS, Physique des Mineraux et Magmas, F-75252 Paris 05, (France); Cormier, L. [Univ Paris 06, IMPMC, F-75015 Paris, (France); Hazemann, J. L. [CNRS, Inst Neel, F-38043 Grenoble, (France); De Ligny, D. [Univ Lyon 1, LMLC, CNRS, UMR 5620, F-69622 Villeurbanne, (France); Pascarelli, S. [European Synchrotron Radiat Facil, F-38043 Grenoble, (France); Vickridge, I. [Univ Paris 06, INSP, F-75015 Paris, (France)

2008-07-01

The kinetics and the mechanisms of iron redox reactions in molten Fe-bearing pyroxene compositions have been investigated by Raman spectroscopy and X-ray absorption Near Edge Structure (XANES) experiments at the iron K-edge. The former experiments have been made only near the glass transition whereas the latter have also been performed from about 1300 to 2100 K. The same kinetics are observed with both techniques. They are described by characteristic times that depend primarily on temperature and not on the initial redox state. At high temperatures, where both kinds of reactions could be investigated, these times are similar for oxidation and reduction. From these characteristic times we have calculated as a function of temperature and composition a parameter termed effective redox diffusivity. For a given melt, the diffusivities follow two distinct Arrhenius laws, which indicate that the mechanisms of the redox reaction are not the same near the glass transition and at high temperatures. As is now well established, diffusion of divalent cations is the dominant mechanism at low temperatures but the enhanced kinetics observed for alkali-bearing melts indicate that Li{sup +} and Na{sup +} also participate in ionic transport. At super-liquidus temperatures, in contrast, diffusion of oxygen represents the dominant mechanism. (authors)

Iron oxides characterization by Moessbauer spectroscopy

International Nuclear Information System (INIS)

Basurto Sanchez, R.

1993-01-01

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

Fabrication and characterization of iron oxide dextran composite layers

Science.gov (United States)

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

2018-02-01

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

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

NARCIS (Netherlands)

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

2009-01-01

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

Solubility of Hydrogen and Nitrogen in liquid cast iron during melting and mold filling

OpenAIRE

Diószegi, Attila; Elfsberg, Jessica; Diószegi, Zoltán

2016-01-01

Defect formation like gas- and shrinkage porosity at cast iron component production is related to the content of gaseous elements in the liquid metal. The present work investigate the solubility of hydrogen and nitrogen in liquid iron aimed for production of lamellar and compacted graphite cast iron. The used methods and instruments are a combination of commercial measuring devices and novel experimental assemblies for measuring solubility of hydrogen and nitrogen during melting and mold fill...

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

Science.gov (United States)

Knipping, Jaayke L.; Bilenker, Laura D.; Simon, Adam C.; Reich, Martin; Barra, Fernando; Deditius, Artur P.; Wälle, Markus; Heinrich, Christoph A.; Holtz, François; Munizaga, Rodrigo

2015-12-01

Iron oxide-apatite (IOA) deposits are an important source of iron and other elements (e.g., REE, P, U, Ag and Co) vital to modern society. However, their formation, including the namesake Kiruna-type IOA deposit (Sweden), remains controversial. Working hypotheses include a purely magmatic origin involving separation of an Fe-, P-rich, volatile-rich oxide melt from a Si-rich silicate melt, and precipitation of magnetite from an aqueous ore fluid, which is either of magmatic-hydrothermal or non-magmatic surface or metamorphic origin. In this study, we focus on the geochemistry of magnetite from the Cretaceous Kiruna-type Los Colorados IOA deposit (∼350 Mt Fe) located in the northern Chilean Iron Belt. Los Colorados has experienced minimal hydrothermal alteration that commonly obscures primary features in IOA deposits. Laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) transects and electron probe micro-analyzer (EPMA) wavelength-dispersive X-ray (WDX) spectrometry mapping demonstrate distinct chemical zoning in magnetite grains, wherein cores are enriched in Ti, Al, Mn and Mg. The concentrations of these trace elements in magnetite cores are consistent with igneous magnetite crystallized from a silicate melt, whereas magnetite rims show a pronounced depletion in these elements, consistent with magnetite grown from an Fe-rich magmatic-hydrothermal aqueous fluid. Further, magnetite grains contain polycrystalline inclusions that re-homogenize at magmatic temperatures (>850 °C). Smaller inclusions (500 ppm) concentrations.

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

International Nuclear Information System (INIS)

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

1993-01-01

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

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

Science.gov (United States)

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

2014-03-01

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

Simulation experiment on the flooding behaviour of core melts: KATS-9

International Nuclear Information System (INIS)

Fieg, G.; Massier, H.; Schuetz, W.; Stegmaier, U.; Stern, G.

2000-11-01

For future Light Water Reactors special devices (core catchers) are being developed to prevent containment failure by basement erosion after reactor pressure vessel meltthrough during a core meltdown accident. Quick freezing of the molten core masses is desirable to reduce release of radioactivity. Several concepts of core catcher devices have been proposed based on the spreading of corium melt onto flat surfaces with subsequent water cooling. A KATS-experiment has been performed to investigate the flooding behaviour of high temperature melts using alumina-iron thermite melts as a simulant. The oxidic thermite melt is conditioned by adding other oxides to simulate a realistic corium melt as close as possible in terms of liquidus and solidus temperatures. Before flooding with water, spreading of the separate oxidic and metallic melts has been done in one-dimensional channels with a silicate concrete as the substrate. The flooding rate was, in relation to the melt surface, identical to the flooding rate in EPR. (orig.) [de

The Nucleation Potency of In Situ-Formed Oxides in Liquid Iron

Science.gov (United States)

Xu, Mingqin; Wang, Lu; Lu, Wenquan; Zeng, Long; Nadendla, Hari-Babu; Wang, Yun; Li, Jun; Hu, Qiaodan; Xia, Mingxu; Li, Jianguo

2018-03-01

The nucleation potency of iron oxides was verified experimentally through nucleation undercooling of liquid iron using aerodynamic levitation technology for minimized container contaminations. Steady undercooling values were subsequently obtained from multiple melting and freezing thermal cycles, with the average undercooling values of 223 K ± 3 K and 75 K ± 6 K (223 °C ± 3 °C and 75 °C ± 6 °C) for FeO-contained liquid and Fe3O4-contained liquid, respectively. The statistical results showed a negligible difference in the sizes and numbers of particles between FeO and Fe3O4 particles, indicating that the nucleation potency difference is attributed to the nature of nucleants rather than particle size or numbers. Furthermore, high-resolution transmission electron microscopy analysis showed that the potential nucleation interfaces can be assumed as { 1 1 0}_{{δ {{-Fe}}}} //( 0 0\\bar{2})_{FeO} and { 1 1 2}_{{δ {{-Fe}}}} //(\\bar{2} 0 2 )_{{{Fe}3 {O}4 }} , based on the detected exposed crystal planes of the oxide particles. Both the interfaces have relatively large values of lattice misfit, consistent with the experimentally measured undercooling based on Turnbull's lattice matching theory.

Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

Science.gov (United States)

Evans, K.; Ferris, F.

2009-05-01

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

Atomistic simulation of the premelting of iron and aluminum : Implications for high-pressure melting-curve measurements

NARCIS (Netherlands)

Starikov, Sergey V.; Stegailov, Vladimir V.

2009-01-01

Using atomistic simulations we show the importance of the surface premelting phenomenon for the melting-curve measurements at high pressures. The model under consideration mimics the experimental conditions deployed for melting studies with diamond-anvil cells. The iron is considered in this work

Reduction Behaviors of Carbon Composite Iron Oxide Briquette Under Oxidation Atmosphere

Energy Technology Data Exchange (ETDEWEB)

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

2017-01-15

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

Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

Energy Technology Data Exchange (ETDEWEB)

Dr. Subodh K. Das; Shridas Ningileri

2006-03-17

This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was

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

Science.gov (United States)

Bonnefoy, Violaine; Holmes, David S

2012-07-01

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

Synthesis and characterization of dextran-coated iron oxide nanoparticles

Science.gov (United States)

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

2018-03-01

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

One step paired electrochemical synthesis of iron and iron oxide nanoparticles

Directory of Open Access Journals (Sweden)

Ordoukhanian Juliet

2016-09-01

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

Preparation and characterization of polyindole - iron oxide nanocomposite electrolyte

International Nuclear Information System (INIS)

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

2009-01-01

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

Iron migration from the anode surface in alumina electrolysis

Energy Technology Data Exchange (ETDEWEB)

Zhuravleva, Elena N.; Drozdova, Tatiana N.; Ponomareva, Svetlana V. [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Kirik, Sergei D., E-mail: kiriksd@yandex.ru [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Institute of Chemistry and Chemical Technology SB RAS, Krasnoyarsk, 660036 (Russian Federation)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Corrosion destruction of two-component iron-based alloys in high-temperature aluminum electrolysis in the cryolite alumina melt has been studied. Black-Right-Pointing-Pointer It was found that at the first stage oxidative polarization of iron atoms on the anode surface into Fe{sup 2+} takes place. Black-Right-Pointing-Pointer Fe{sup 2+} interacts with cryolite melt producing FeF{sub 2}. Black-Right-Pointing-Pointer FeF{sub 2} gives oxides FeAl{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}. Black-Right-Pointing-Pointer The participation of oxygen in the corrosion has not been observed. - Abstract: Corrosion destruction of two-component iron-based alloys used as an anode in high-temperature alumina electrolysis in the melt of NaF/KF/AlF{sub 3} electrolyte has been considered. Ni, Si, Cu, Cr, Mn, Al, Ti in the amount of up to 10% have been tested as the dopants to an anode alloys. The composition of the corrosion products has been studied using X-ray diffraction, scanning electron microscopy and electron microprobe analysis. It has been established that the anode corrosion is induced by a surface electrochemical polarization and iron atom oxidation. Iron ions come into an exchange interaction with the fluoride components of the melted electrolyte, producing FeF{sub 2}. The last interacts with oxyfluoride species transforming into the oxide forms: FeAl{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}. Due to the low solubility, the iron oxides are accumulated in the near-electrode sheath. The only small part of iron from anode migrates to cathode that makes an production of high purity aluminum of a real task. The alloy dopants are also subjected to corrosion in accordance with electromotive series resulting corrosion tunnels on the anode surface. The oxides are final compounds which collect in the same area. The corrosion products form an anode shell which is electronic conductor at electrolysis temperature. The

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

International Nuclear Information System (INIS)

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

2007-01-01

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

Hydrothermal oxidation in the Biwabik Iron Formation, MN, USA

Science.gov (United States)

Losh, Steven; Rague, Ryan

2018-02-01

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

Oxidative Stress and the Homeodynamics of Iron Metabolism

Science.gov (United States)

Bresgen, Nikolaus; Eckl, Peter M.

2015-01-01

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

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

NARCIS (Netherlands)

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

1990-01-01

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

Iron Oxide Deposition from Aqueous Solution and Iron Formations on Mars

Science.gov (United States)

Catling, David; Moore, Jeff

2000-01-01

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

Phosphorus Retention (32P) by synthetic iron oxides

International Nuclear Information System (INIS)

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

1975-02-01

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

Experimental and thermodynamic evaluation of the melting behavior of irradiated oxide fuels

International Nuclear Information System (INIS)

Adamson, M.G.; Aitken, E.A.; Caputi, R.W.

1985-01-01

Onset of melting is an important performance limit for irradiated UO 2 and UO 2 -based nuclear reactor fuels. Melting (solidus) temperatures are reasonably well known for starting fuel materials such as UO 2 and (U,PU)O 2 , however the influence of burnup on oxide fuel melting behavior continues to represent an area of considerable uncertainty. In this paper we report the results of a variety of melting temperature measurements on pseudo-binary fuel-fissia mixtures such as UO 2 -PUO 2 , UO 2 -CeO 2 , UO 2 -BaO, UO 2 -SrO, UO 2 -BaZrO 3 and UO 2 -SrZrO 3 . These measurements were performed using the thermal arrest technique on tungsten-encapsulated specimens. Several low melting eutectics, the existence of which had previously been inferred from post-irradiation examinations of high burnup mixed oxide fuels, were characterized in the course of the investigation. Also, an assessment of melting temperature changes in irradiated oxide fuels due to the production and incorporation of soluble oxidic fission products was performed by application of solution theory to the available pseudo-binary phase diagram data. The results of this assessment suggest that depression of oxide fuel solidus temperatures by dissolved fission products is substantially less than that indicated by earlier experimental studies. (orig.)

Iron oxides as a cause of GPR reflections

NARCIS (Netherlands)

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

2002-01-01

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

Labeling Efficacy of Superparamagnetic Iron Oxide Nanoparticles to Human Neural Stem Cells: Comparison of Ferumoxides, Monocrystalline Iron Oxide, Cross-linked Iron Oxide (CLIO)-NH2 and tat-CLIO

International Nuclear Information System (INIS)

Song, Mi Yeoun; Moon, Woo Kyung; Kim, Yun Hee; Song, In Chan; Yoon, Byung Woo; Lim, Dong Yeol

2007-01-01

We wanted to compare the human neural stem cell (hNSC) labeling efficacy of different superparamagnetic iron oxide nanoparticles (SPIONs), namely, ferumoxides, monocrystalline iron oxide (MION), cross-linked iron oxide (CLIO)-NH 2 and tat-CLIO. The hNSCs (5x10 5 HB1F3 cells/ml) were incubated for 24 hr in cell culture media that contained 25 μg/ml of ferumoxides, MION or CLIO-NH 2 , and with or without poly-L-lysine (PLL) and tat-CLIO. The cellular iron uptake was analyzed qualitatively with using a light microscope and this was quantified via atomic absorption spectrophotometry. The visibility of the labeled cells was assessed with MR imaging. The incorporation of SPIONs into the hNSCs did not affect the cellular proliferations and viabilities. The hNSCs labeled with tat-CLIO showed the longest retention, up to 72 hr, and they contained 2.15± 0.3 pg iron/cell, which are 59 fold, 430 fold and six fold more incorporated iron than that of the hNSCs labeled with ferumoxides, MION or CLIO-NH 2 , respectively. However, when PLL was added, the incorporation of ferumoxides, MION or CLIO-NH 2 into the hNSCs was comparable to that of tat-CLIO. For MR imaging, hNSCs can be efficiently labeled with tat-CLIO alone or with a combination of ferumoxides, MION, CLIO-NH 2 and the transfection agent PLL

Labeling Efficacy of Superparamagnetic Iron Oxide Nanoparticles to Human Neural Stem Cells: Comparison of Ferumoxides, Monocrystalline Iron Oxide, Cross-linked Iron Oxide (CLIO)-NH2 and tat-CLIO

Science.gov (United States)

Song, Miyeoun; Kim, Yunhee; Lim, Dongyeol; Song, In-Chan; Yoon, Byung-Woo

2007-01-01

Objective We wanted to compare the human neural stem cell (hNSC) labeling efficacy of different superparamagnetic iron oxide nanoparticles (SPIONs), namely, ferumoxides, monocrystalline iron oxide (MION), cross-linked iron oxide (CLIO)-NH2 and tat-CLIO. Materials and Methods The hNSCs (5 × 105 HB1F3 cells/ml) were incubated for 24 hr in cell culture media that contained 25 µg/ml of ferumoxides, MION or CLIO-NH2, and with or without poly-L-lysine (PLL) and tat-CLIO. The cellular iron uptake was analyzed qualitatively with using a light microscope and this was quantified via atomic absorption spectrophotometry. The visibility of the labeled cells was assessed with MR imaging. Results The incorporation of SPIONs into the hNSCs did not affect the cellular proliferations and viabilities. The hNSCs labeled with tat-CLIO showed the longest retention, up to 72 hr, and they contained 2.15 ± 0.3 pg iron/cell, which are 59 fold, 430 fold and six fold more incorporated iron than that of the hNSCs labeled with ferumoxides, MION or CLIO-NH2, respectively. However, when PLL was added, the incorporation of ferumoxides, MION or CLIO-NH2 into the hNSCs was comparable to that of tat-CLIO. Conclusion For MR imaging, hNSCs can be efficiently labeled with tat-CLIO alone or with a combination of ferumoxides, MION, CLIO-NH2 and the transfection agent PLL. PMID:17923778

High pressure Moessbauer spectroscopy of perovskite iron oxide

International Nuclear Information System (INIS)

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

2003-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-05-15

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

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Structural transformations of heat-treated bacterial iron oxide

Energy Technology Data Exchange (ETDEWEB)

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

2015-04-01

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

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

Science.gov (United States)

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

2016-05-01

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

On barium oxide solubility in barium-containing chloride melts

International Nuclear Information System (INIS)

Nikolaeva, Elena V.; Zakiryanova, Irina D.; Bovet, Andrey L.; Korzun, Iraida V.

2016-01-01

Oxide solubility in chloride melts depends on temperature and composition of molten solvent. The solubility of barium oxide in the solvents with barium chloride content is essentially higher than that in molten alkali chlorides. Spectral data demonstrate the existence of oxychloride ionic groupings in such melts. This work presents the results of the BaO solubility in two molten BaCl 2 -NaCl systems with different barium chloride content. The received data together with earlier published results revealed the main regularities of BaO solubility in molten BaO-BaCl 2 -MCl systems.

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

Science.gov (United States)

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

2018-02-28

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

Stabilization and functionalization of iron oxide nanoparticles for biomedical applications

Science.gov (United States)

Amstad, Esther; Textor, Marcus; Reimhult, Erik

2011-07-01

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

Iron accumulation with age, oxidative stress and functional decline.

Directory of Open Access Journals (Sweden)

Jinze Xu

2008-08-01

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

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

Science.gov (United States)

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

1972-01-01

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

Electrical resistivity discontinuity of iron along the melting curve

Science.gov (United States)

Wagle, Fabian; Steinle-Neumann, Gerd

2018-04-01

Discontinuous changes of electrical resistivity ρel (increase), density ϱ and isothermal compressibility βT (decrease) occur across the melting temperature of metals and can be directly related by Ziman's theory in the long-wavelength approximation. By evaluating experimental data at ambient pressure, we show that Ziman's approximation holds for iron and other simple and transition metals. Using a thermodynamic model to determine βT for γ-, ɛ- and liquid Fe and a previously published model for ρel of liquid Fe, we apply Ziman's approximation to calculate ρel of solid Fe along the melting curve. For pure Fe, we find the discontinuity in ρel to decrease with pressure and to be negligibly small at inner core boundary conditions. However, if we account for light element enrichment in the liquid outer core, the electrical resistivity decrease across the inner core boundary is predicted to be as large as 36 per cent.

Manganese and iron oxidation by fungi isolated from building stone.

Science.gov (United States)

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

1994-01-01

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

Moessbauer effect study of oxidation and coordination states of iron in some sodium borate glasse:;

International Nuclear Information System (INIS)

Eissa, N.A.; Sanad, A.M.; Youssef, S.M.; El-Henawii, S.A.; Gomaa, S.Sh.; Mostafa, A.G.

1980-01-01

A structural study of some sodium borate glasses containing iron was carried out applying ME spectroscopy. Both oxidation and coordination states of iron were investigated under the effect of gradual replacing of sodium carbonate by sodium nitrate in the glass batches. The glasses were melted in porcelain crucibles using an electrically heated furnace at 1000+-10 deg C, then were quenched on a steel plate at room temperature (R.T.). The ME source was 20 mCi radioactive Co-57 in chromium. The obtained ME spectra indicated that at lower sodium nitrate content both Fe 2+ and Fe 3+ are present in these glasses. At moderate concentrations some Fe 3+ ions were separated in a crystalline phase and the rest of the iron ions appeared as ferric ions in glassy state. At high sodium nitrate content only Fe 3+ ions in glassy state were detected. The values of the ME parameters for all iron ions indicated that all of them are in the octahedral coordination state. The density measurements confirm the separation of a crystalline phase at moderate sodium nitrate content. (author)

Mechanistic Study of Monodisperse Iron Oxide Nanocrystals ...

African Journals Online (AJOL)

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

Synthesis and magnetic characterizations of uniform iron oxide nanoparticles

International Nuclear Information System (INIS)

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

2014-01-01

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

Mechanism of anodic oxidation of molybdenum and tungsten in nitrate-nitrite melts

International Nuclear Information System (INIS)

Yurkinskij, V.P.; Firsova, E.G.; Morachevskij, A.G.

1987-01-01

The mechanism of anode oxidation of tungsten and molybdenum in NaNO 3 -KNO 3 (50 mass %) nitrate-nitrite melts with NaNO 2 -KNO 2 (0.5-50 mass %) addition and in NaNO 2 -KNO 2 (35 mole %) nitrite melt in the 516-580 K temperature range is studied. It is supposed that the process of anode dissloving of the mentioned metals in nitrite melt and nitrate-nitrite mixtures is two-electron. Formation of oxide passivating film is possible under electrolysis on the anode surface, the film is then dissolved in nitrate-nitrite melt with formation of molybdates or tungstates

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

International Nuclear Information System (INIS)

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

1996-01-01

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

Magnetic and gravity gradiometry framework for Mesoproterozoic iron oxide-apatite and iron oxide-copper-gold deposits, southeast Missouri, USA

Science.gov (United States)

McCafferty, Anne E.; Phillips, Jeffrey; Driscoll, Rhonda L.

2016-01-01

High-resolution airborne magnetic and gravity gradiometry data provide the geophysical framework for evaluating the exploration potential of hidden iron oxide deposits in Mesoproterozoic basement rocks of southeast Missouri. The data are used to calculate mineral prospectivity for iron oxide-apatite (IOA) ± rare earth element (REE) and iron oxide-copper-gold (IOCG) deposits. Results delineate the geophysical footprints of all known iron oxide deposits and reveal several previously unrecognized prospective areas. The airborne data are also inverted to three-dimensional density and magnetic susceptibility models over four concealed deposits at Pea Ridge (IOA ± REE), Boss (IOCG), Kratz Spring (IOA), and Bourbon (IOCG). The Pea Ridge susceptibility model shows a magnetic source that is vertically extensive and traceable to a depth of greater than 2 km. A smaller density source, located within the shallow Precambrian basement, is partly coincident with the magnetic source at Pea Ridge. In contrast, the Boss models show a large (625-m-wide), vertically extensive, and coincident dense and magnetic stock with shallower adjacent lobes that extend more than 2,600 m across the shallow Precambrian paleosurface. The Kratz Spring deposit appears to be a smaller volume of iron oxides and is characterized by lower density and less magnetic rock compared to the other iron deposits. A prospective area identified south of the Kratz Spring deposit shows the largest volume of coincident dense and nonmagnetic rock in the subsurface, and is interpreted as prospective for a hematite-dominant lithology that extends from the top of the Precambrian to depths exceeding 2 km. The Bourbon deposit displays a large bowl-shaped volume of coincident high density and high-magnetic susceptibility rock, and a geometry that suggests the iron mineralization is vertically restricted to the upper parts of the Precambrian basement. In order to underpin the evaluation of the prospectivity and three

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

International Nuclear Information System (INIS)

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

2010-01-01

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

IRON AND FREE RADICAL OXIDATIONS IN CELL MEMBRANES

Science.gov (United States)

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

2013-01-01

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

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

Directory of Open Access Journals (Sweden)

Eleonora Mussatti

2013-02-01

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

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

Directory of Open Access Journals (Sweden)

Eleonora Mussatti

2012-01-01

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

Iron-oxidation processes in an electroflocculation (electrocoagulation) cell

Energy Technology Data Exchange (ETDEWEB)

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

2009-11-15

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

Iron-oxidation processes in an electroflocculation (electrocoagulation) cell

International Nuclear Information System (INIS)

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

2009-01-01

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

High pressure Moessbauer spectroscopy of perovskite iron oxide

CERN Document Server

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

2003-01-01

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

X-Ray Photoelectron Spectroscopic Characterization of Iron Oxide Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

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

2017-05-31

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

Iron oxide redox chemistry and nuclear fuel disposal

International Nuclear Information System (INIS)

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

1997-04-01

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

Ferrite grade iron oxides from ore rejects

Indian Academy of Sciences (India)

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-12-02

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-09-01

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

Iron oxide and gold nanoparticles in cancer therapy

Energy Technology Data Exchange (ETDEWEB)

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

2016-08-02

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

High-temperature oxidation of tungsten covered by layer of glass-enamel melt

International Nuclear Information System (INIS)

Vasnetsova, V.B.; Shardakov, N.T.; Kudyakov, V.Ya.; Deryabin, V.A.

1997-01-01

Corrosion losses of tungsten covered by the layer of glass-enamel melt were determined at 800, 850, 900, 950 deg C. It is shown that the rate of high-temperature oxidation of tungsten decreases after application of glass-enamel melt on its surface. This is probably conditioned by reduction of area of metal interaction with oxidizing atmosphere

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

Science.gov (United States)

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

2010-06-01

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

Acid monolayer functionalized iron oxide nanoparticle catalysts

Science.gov (United States)

Ikenberry, Myles

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

Synthesis and applications of nano-structured iron oxides/hydroxides

African Journals Online (AJOL)

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

Progress in electrochemical synthesis of magnetic iron oxide nanoparticles

International Nuclear Information System (INIS)

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

2014-01-01

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

Selectivity and Activity of Iron Molybdate Catalysts in Oxidation of Methanol

Directory of Open Access Journals (Sweden)

Khalid Khazzal Hummadi

2009-06-01

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

Magnetic behavior of iron oxide nanoparticle-biomolecule assembly

International Nuclear Information System (INIS)

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

2005-01-01

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

Iron oxide nanotubes synthesized via template-based electrodeposition

Science.gov (United States)

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

2014-04-01

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

Premixing and steam explosion phenomena in the tests with stratified melt-coolant configuration and binary oxidic melt simulant materials

Energy Technology Data Exchange (ETDEWEB)

Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se; Grishchenko, Dmitry, E-mail: dmitry@safety.sci.kth.se; Konovalenko, Alexander, E-mail: kono@kth.se; Karbojian, Aram, E-mail: karbojan@kth.se

2017-04-01

Highlights: • Steam explosion in stratified melt-coolant configuration is studied experimentally. • Different binary oxidic melt simulant materials were used. • Five spontaneous steam explosions were observed. • Instability of melt-coolant interface and formation of premixing layer was observed. • Explosion strength is influenced by melt superheat and water subcooling. - Abstract: Steam explosion phenomena in stratified melt-coolant configuration are considered in this paper. Liquid corium layer covered by water on top can be formed in severe accident scenarios with (i) vessel failure and release of corium melt into a relatively shallow water pool; (ii) with top flooding of corium melt layer. In previous assessments of potential energetics in stratified melt-coolant configuration, it was assumed that melt and coolant are separated by a stable vapor film and there is no premixing prior to the shock wave propagation. This assumption was instrumental for concluding that the amount of energy that can be released in such configuration is not of safety importance. However, several recent experiments carried out in Pouring and Under-water Liquid Melt Spreading (PULiMS) facility with up to 78 kg of binary oxidic corium simulants mixtures have resulted in spontaneous explosions with relatively high conversion ratios (order of one percent). The instability of the melt-coolant interface, melt splashes and formation of premixing layer were observed in the tests. In this work, we present results of experiments carried out more recently in steam explosion in stratified melt-coolant configuration (SES) facility in order to shed some light on the premixing phenomena and assess the influence of the test conditions on the steam explosion energetics.

High rate flame synthesis of highly crystalline iron oxide nanorods

International Nuclear Information System (INIS)

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

2008-01-01

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

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

Science.gov (United States)

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

2011-12-06

The adsorption of poly(vinyl formamide) (PVFA) and the statistic copolymers poly(vinyl formamide-co-vinyl amine) (PVFA-co-PVAm) onto zinc and iron metal particles as well as their oxides was investigated. The adsorbates were characterized by means of XPS, DRIFT spectroscopy, wet chemical analysis, and solvatochromic probes. Dicyano-bis-(1,10-phenanthroline)-iron(II) (1), 3-(4-amino-3-methylphenyl)-7-phenyl-benzo-[1,2-b:4,5-b']difuran-2,6-dione (2), and 4-tert-butyl-2-(dicyano-methylene)-5-[4-(diethylamino)-benzylidene]-Δ(3)-thiazoline (3) as solvatochromic probes were coadsorbed onto zinc oxide to measure various effects of surface polarity. The experimental findings showed that the adsorption mechanism of PVFA and PVFA-co-PVAm strongly depends on the degree of hydrolysis of PVFA and pH values and also on the kind of metal or metal oxide surfaces that were employed as adsorbents. The adsorption mechanism of PVFA/PVFA-co-PVAm onto zinc oxide and iron oxide surfaces is mainly affected by electrostatic interactions. Particularly in the region of pH 5, the adsorption of PVFA/PVFA-co-PVAm onto zinc and iron metal particles is additionally influenced by redox processes, dissolution, and complexation reactions. © 2011 American Chemical Society

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

Science.gov (United States)

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

2014-01-01

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

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

International Nuclear Information System (INIS)

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

2011-01-01

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

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

DEFF Research Database (Denmark)

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

2015-01-01

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

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

DEFF Research Database (Denmark)

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

2013-01-01

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

Partitioning ratio of depleted uranium during a melt decontamination by arc melting

International Nuclear Information System (INIS)

Min, Byeong Yeon; Choi, Wang Kyu; Oh, Won Zin; Jung, Chong Hun

2008-01-01

In a study of the optimum operational condition for a melting decontamination, the effects of the basicity, slag type and slag composition on the distribution of depleted uranium were investigated for radioactively contaminated metallic wastes of iron-based metals such as stainless steel (SUS 304L) in a direct current graphite arc furnace. Most of the depleted uranium was easily moved into the slag from the radioactive metal waste. The partitioning ratio of the depleted uranium was influenced by the amount of added slag former and the slag basicity. The composition of the slag former used to capture contaminants such as depleted uranium during the melt decontamination process generally consists of silica (SiO 2 ), calcium oxide (CaO) and aluminum oxide (Al 2 O 3 ). Furthermore, calcium fluoride (CaF 2 ), magnesium oxide (MgO), and ferric oxide (Fe 2 O 3 ) were added to increase the slag fluidity and oxidative potential. The partitioning ratio of the depleted uranium was increased as the amount of slag former was increased. Up to 97% of the depleted uranium was captured between the ingot phase and the slag phase. The partitioning ratio of the uranium was considerably dependent on the basicity and composition of the slag. The optimum condition for the removal of the depleted uranium was a basicity level of about 1.5. The partitioning ratio of uranium was high, exceeding 5.5x10 3 . The slag formers containing calcium fluoride (CaF 2 ) and a high amount of silica proved to be more effective for a melt decontamination of stainless steel wastes contaminated with depleted uranium

Melting temperature of uranium - plutonium mixed oxide fuel

Energy Technology Data Exchange (ETDEWEB)

Ishii, Tetsuya; Hirosawa, Takashi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

1997-08-01

Fuel melting temperature is one of the major thermodynamical properties that is used for determining the design criteria on fuel temperature during irradiation in FBR. In general, it is necessary to evaluate the correlation of fuel melting temperature to confirm that the fuel temperature must be kept below the fuel melting temperature during irradiation at any conditions. The correlations of the melting temperature of uranium-plutonium mixed oxide (MOX) fuel, typical FBR fuel, used to be estimated and formulized based on the measured values reported in 1960`s and has been applied to the design. At present, some experiments have been accumulated with improved experimental techniques. And it reveals that the recent measured melting temperatures does not agree well to the data reported in 1960`s and that some of the 1960`s data should be modified by taking into account of the recent measurements. In this study, the experience of melting temperature up to now are summarized and evaluated in order to make the fuel pin design more reliable. The effect of plutonium content, oxygen to metal ratio and burnup on MOX fuel melting was examined based on the recent data under the UO{sub 2} - PuO{sub 2} - PuO{sub 1.61} ideal solution model, and then formulized. (J.P.N.)

Melting temperature of uranium - plutonium mixed oxide fuel

International Nuclear Information System (INIS)

Ishii, Tetsuya; Hirosawa, Takashi

1997-08-01

Fuel melting temperature is one of the major thermodynamical properties that is used for determining the design criteria on fuel temperature during irradiation in FBR. In general, it is necessary to evaluate the correlation of fuel melting temperature to confirm that the fuel temperature must be kept below the fuel melting temperature during irradiation at any conditions. The correlations of the melting temperature of uranium-plutonium mixed oxide (MOX) fuel, typical FBR fuel, used to be estimated and formulized based on the measured values reported in 1960's and has been applied to the design. At present, some experiments have been accumulated with improved experimental techniques. And it reveals that the recent measured melting temperatures does not agree well to the data reported in 1960's and that some of the 1960's data should be modified by taking into account of the recent measurements. In this study, the experience of melting temperature up to now are summarized and evaluated in order to make the fuel pin design more reliable. The effect of plutonium content, oxygen to metal ratio and burnup on MOX fuel melting was examined based on the recent data under the UO 2 - PuO 2 - PuO 1.61 ideal solution model, and then formulized. (J.P.N.)

Iron single crystal growth from a lithium-rich melt

Science.gov (United States)

Fix, M.; Schumann, H.; Jantz, S. G.; Breitner, F. A.; Leineweber, A.; Jesche, A.

2018-03-01

α -Fe single crystals of rhombic dodecahedral habit were grown from a Li84N12Fe∼3 melt. Crystals of several millimeter along a side form at temperatures around T ≈ 800 ° C. Upon further cooling the growth competes with the formation of Fe-doped Li3N. The b.c.c. structure and good sample quality of α -Fe single crystals were confirmed by X-ray and electron diffraction as well as magnetization measurements and chemical analysis. A nitrogen concentration of 90 ppm was detected by means of carrier gas hot extraction. Scanning electron microscopy did not reveal any sign of iron nitride precipitates.

Synthesis of iron oxide nanoparticles via sonochemical method and their characterization

Institute of Scientific and Technical Information of China (English)

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

2011-01-01

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

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

DEFF Research Database (Denmark)

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

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

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

Indian Academy of Sciences (India)

WINTEC

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

Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Wael Ahmed Abou Taleb Sayed

2011-01-13

This work presents the experimental results of the synthesis of unsupported and supported SiC iron oxide nanoparticles and their catalytic activity towards ethanol partial oxidation. For comparison, further unsupported iron oxide phases were investigated towards the ethanol partial oxidation. These {gamma}-Fe{sub 2}O{sub 3} and {alpha}/{gamma}-Fe{sub 2}O{sub 3} phase catalysts were prepared by the CVS method using Fe(CO){sub 5} as precursor, supplied by another author. The {alpha}-Fe{sub 2}O{sub 3} and SiC nanoparticles were prepared by the CVS method using a home made hot wall reactor technique at atmospheric pressure. Ferrocene and tetramethylsilane were used as precursor for the production process. Process parameters of precursor evaporation temperature, precursor concentration, gas mixture velocity and gas mixture dilution were investigated and optimised to produce particle sizes in a range of 10 nm. For Fe{sub 2}O{sub 3}/SiC catalyst series production, a new hot wall reactor setup was used. The particles were produced by simultaneous thermal decomposition of ferrocene and tetramethylsilane in one reactor from both sides. The production parameters of inlet tube distance inside the reactor, precursor evaporation temperature and carrier gas flow were investigated to produce a series of samples with different iron oxide content. The prepared catalysts composition, physical and chemical properties were characterized by XRD, EDX, SEM, BET surface area, FTIR, XPS and dynamic light scattering (DLS) techniques. The catalytic activity for the ethanol gas-phase oxidation was investigated in a temperature range from 260 C to 290 C. The product distributions obtained over all catalysts were analysed with mass spectrometry analysis tool. The activity of bulk Fe{sub 2}O{sub 3} and SiC nanoparticles was compared with prepared nano-iron oxide phase catalysts. The reaction parameters, such as reaction temperature and O{sub 2}/ethanol ratio were investigated. The catalysts

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

International Nuclear Information System (INIS)

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

1979-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1979-01-01

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

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

Science.gov (United States)

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

2017-04-01

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

Magnetic iron oxide for contrast-enhanced MR imaging

International Nuclear Information System (INIS)

Fahlvik, A.K.

1991-05-01

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

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

Science.gov (United States)

Wu, Peng

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

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

Science.gov (United States)

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

1993-01-01

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

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Thermochemically active iron titanium oxide materials

Energy Technology Data Exchange (ETDEWEB)

Coker, Eric Nicholas; Miller, James E.

2018-01-16

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

Solid-state Water-mediated Transport Reduction of Nanostructured Iron Oxides

International Nuclear Information System (INIS)

Smirnov, Vladimir M.; Povarov, Vladimir G.; Voronkov, Gennadii P.; Semenov, Valentin G.; Murin, Igor' V.; Gittsovich, Viktor N.; Sinel'nikov, Boris M.

2001-01-01

The Fe 2+ /Fe 3+ ratio in two-dimensional iron oxide nanosructures (nanolayers with a thickness of 0.3-1.5 nm on silica surface) may be precisely controlled using the transport reduction (TR) technique. The species ≡-O-Fe(OH) 2 and (≡Si-O-) 2 -FeOH forming the surface monolayer are not reduced at 400-600 deg. C because of their covalent bonding to the silica surface, as demonstrated by Moessbauer spectroscopy. Iron oxide microparticles (microstructures) obtained by the impregnation technique, being chemically unbound to silica, are subjected to reduction at T ≥ 500 deg. C with formation of metallic iron in the form of α-Fe. Transport reduction of supported nanostructures (consisting of 1 or 4 monolayers) at T ≥ 600 deg. C produces bulk iron(II) silicate and metallic iron phases. The structural-chemical transformations occurring in transport reduction of supported iron oxide nanolayers are proved to be governed by specific phase processes in the nanostructures themselves

Molecular and parametric imaging with iron oxides

International Nuclear Information System (INIS)

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

2007-01-01

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

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

Science.gov (United States)

Yin, Yongyuan; Guo, Xuetao; Peng, Dan

2018-08-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-02-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1989-09-01

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

Effect of Ca-Fe oxides additives on NOx reduction in iron ore sintering

Institute of Scientific and Technical Information of China (English)

Zhi-yuan Yu; Xiao-hui Fan; Min Gan; Xu-ling Chen

2017-01-01

As the emission control regulations get stricter, the NOx reduction in the sintering process becomes an important environmental concern owing to its role in the formation of photochemical smog and acid rain. The NOx emissions from the sintering machine account for 48% of total amount from the iron and steel industry.Thus, it is essential to reduce NOx emissions from the sintering machine, for the achievement of clean production of sinter.Ca-Fe oxides, serving as the main binding phase in the sinter, are therefore used as additives into the sintering mixture to reduce NOx emissions.The results show that the NOx re-duction ratio achieves 27.76% with 8% Ca-Fe oxides additives since the Ca-Fe oxides can advance the ig-nition and inhibit the nitrogen oxidation compared with the conventional condition.Meanwhile, the exist-ence of Ca-Fe oxides was beneficial to the sinter quality since they were typical low melting point com-pounds.The optimal mass fraction of Ca-Fe oxides additives should be less than 8% since the permeability of sintering bed was significantly decreased with a further increase of the Ca-Fe oxides fines, inhibiting the mineralization reaction of sintering mixture.Additionally, the appropriate particle size can be obtained when mixing an equal amount of Ca-Fe oxides additives of -0.5 mm and 0.5-3.0 mm in size.

Iron oxides photochemical dissolution

International Nuclear Information System (INIS)

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

1987-01-01

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

Methodology of Fault Diagnosis in Ductile Iron Melting Process

Directory of Open Access Journals (Sweden)

Perzyk M.

2016-12-01

Full Text Available Statistical Process Control (SPC based on the Shewhart’s type control charts, is widely used in contemporary manufacturing industry, including many foundries. The main steps include process monitoring, detection the out-of-control signals, identification and removal of their causes. Finding the root causes of the process faults is often a difficult task and can be supported by various tools, including data-driven mathematical models. In the present paper a novel approach to statistical control of ductile iron melting process is proposed. It is aimed at development of methodologies suitable for effective finding the causes of the out-of-control signals in the process outputs, defined as ultimate tensile strength (Rm and elongation (A5, based mainly on chemical composition of the alloy. The methodologies are tested and presented using several real foundry data sets. First, correlations between standard abnormal output patterns (i.e. out-of-control signals and corresponding inputs patterns are found, basing on the detection of similar patterns and similar shapes of the run charts of the chemical elements contents. It was found that in a significant number of cases there was no clear indication of the correlation, which can be attributed either to the complex, simultaneous action of several chemical elements or to the causes related to other process variables, including melting, inoculation, spheroidization and pouring parameters as well as the human errors. A conception of the methodology based on simulation of the process using advanced input - output regression modelling is presented. The preliminary tests have showed that it can be a useful tool in the process control and is worth further development. The results obtained in the present study may not only be applied to the ductile iron process but they can be also utilized in statistical quality control of a wide range of different discrete processes.

Magnetic and Mössbauer spectroscopy studies of nanocrystalline iron oxide aerogels

DEFF Research Database (Denmark)

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

2006-01-01

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

Aqueous dispersion of monodisperse magnetic iron oxide nanocrystals through phase transfer

International Nuclear Information System (INIS)

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

2006-01-01

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

Electron uptake by iron-oxidizing phototrophic bacteria

Energy Technology Data Exchange (ETDEWEB)

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

2014-02-26

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

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

Science.gov (United States)

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

2016-01-01

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

From iron coordination compounds to metal oxide nanoparticles.

Science.gov (United States)

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

2016-01-01

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

From iron coordination compounds to metal oxide nanoparticles

Directory of Open Access Journals (Sweden)

Mihail Iacob

2016-12-01

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

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

Directory of Open Access Journals (Sweden)

Heon Lee

2014-01-01

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

Underestimation of phosphorus fraction change in the supernatant after phosphorus adsorption onto iron oxides and iron oxide-natural organic matter complexes.

Science.gov (United States)

Yan, Jinlong; Jiang, Tao; Yao, Ying; Wang, Jun; Cai, Yuanli; Green, Nelson W; Wei, Shiqiang

2017-05-01

The phosphorus (P) fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid (HA) complexes were analyzed using the ultrafiltration method in this study. With an initial P concentration of 20mg/L (I=0.01mol/L and pH=7), it was shown that the colloid (1kDa-0.45μm) component of P accounted for 10.6%, 11.6%, 6.5%, and 4.0% of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite (FH), goethite (GE), ferrihydrite-humic acid complex (FH-HA), goethite-humic acid complex (GE-HA), respectively. The oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant. And colloidal adsorbent particles co-existing in the supernatant were another important reason for it. Additionally, dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant. Ultimately, we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P, even when considering other contaminants such as organic pollutants, heavy metal ions, and arsenate at the sediment/soil-water interface in the real environment. Copyright © 2016. Published by Elsevier B.V.

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

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Ruifang Huang

2017-11-01

Full Text Available Serpentinization produces molecular hydrogen (H2 that can support communities of microorganisms in hydrothermal fields; H2 results from the oxidation of ferrous iron in olivine and pyroxene into ferric iron, and consequently iron oxide (magnetite or hematite forms. However, the mechanisms that control H2 and iron oxide formation are poorly constrained. In this study, we performed serpentinization experiments at 311 °C and 3.0 kbar on olivine (with <5% pyroxene, orthopyroxene, and peridotite. The results show that serpentine and iron oxide formed when olivine and orthopyroxene individually reacted with a saline starting solution. Olivine-derived serpentine had a significantly lower FeO content (6.57 ± 1.30 wt.% than primary olivine (9.86 wt.%, whereas orthopyroxene-derived serpentine had a comparable FeO content (6.26 ± 0.58 wt.% to that of primary orthopyroxene (6.24 wt.%. In experiments on peridotite, olivine was replaced by serpentine and iron oxide. However, pyroxene transformed solely to serpentine. After 20 days, olivine-derived serpentine had a FeO content of 8.18 ± 1.56 wt.%, which was significantly higher than that of serpentine produced in olivine-only experiments. By contrast, serpentine after orthopyroxene had a slightly higher FeO content (6.53 ± 1.01 wt.% than primary orthopyroxene. Clinopyroxene-derived serpentine contained a significantly higher FeO content than its parent mineral. After 120 days, the FeO content of olivine-derived serpentine decreased significantly (5.71 ± 0.35 wt.%, whereas the FeO content of orthopyroxene-derived serpentine increased (6.85 ± 0.63 wt.% over the same period. This suggests that iron oxide preferentially formed after olivine serpentinization. Pyroxene in peridotite gained some Fe from olivine during the serpentinization process, which may have led to a decrease in iron oxide production. The correlation between FeO content and SiO2 or Al2O3 content in olivine- and

Dextran-modified iron oxide nanoparticles

Czech Academy of Sciences Publication Activity Database

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

2007-01-01

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

Adsorption of trace elements of radionuclides on hydrous iron oxides

International Nuclear Information System (INIS)

Music, S.; Ristic, M.

1988-01-01

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

Linear-chain assemblies of iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

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

2017-07-01

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

Microbial iron mats at the Mid-Atlantic Ridge and evidence that Zetaproteobacteria may be restricted to iron-oxidizing marine systems.

Directory of Open Access Journals (Sweden)

Jarrod J Scott

Full Text Available Chemolithoautotrophic iron-oxidizing bacteria play an essential role in the global iron cycle. Thus far, the majority of marine iron-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine iron-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of iron-oxidizing communities at hydrothermal systems along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent systems on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit using the ROV Jason II. The goal of these efforts was to determine if iron-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high iron(II concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial iron mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of iron-oxyhydroxide structures, indicating that active iron-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these iron mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other iron-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an iron source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests

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

Science.gov (United States)

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

2016-10-01

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

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

Science.gov (United States)

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

2015-11-01

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

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

International Nuclear Information System (INIS)

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

2005-01-01

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

Water clustering on nanostructured iron oxide films

DEFF Research Database (Denmark)

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

2014-01-01

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

Safety assessment of chronic oral exposure to iron oxide nanoparticles

International Nuclear Information System (INIS)

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

2015-01-01

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

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

International Nuclear Information System (INIS)

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

2008-01-01

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

Effect of bicarbonate on iron-mediated oxidation of low-density lipoprotein

Science.gov (United States)

Arai, Hirofumi; Berlett, Barbara S.; Chock, P. Boon; Stadtman, Earl R.

2005-07-01

Oxidation of low-density lipoprotein (LDL) may play an important role in atherosclerosis. We studied the effects of bicarbonate/CO2 and phosphate buffer systems on metal ion-catalyzed oxidation of LDL to malondialdehyde (MDA) and to protein carbonyl and MetO derivatives. Our results revealed that LDL oxidation in mixtures containing free iron or heme derivatives was much greater in bicarbonate/CO2 compared with phosphate buffer. However, when copper was substituted for iron in these mixtures, the rate of LDL oxidation in both buffers was similar. Iron-catalyzed oxidation of LDL was highly sensitive to inhibition by phosphate. Presence of 0.3-0.5 mM phosphate, characteristic of human serum, led to 30-40% inhibition of LDL oxidation in bicarbonate/CO2 buffer. Iron-catalyzed oxidation of LDL to MDA in phosphate buffer was inhibited by increasing concentrations of albumin (10-200 μM), whereas MDA formation in bicarbonate/CO2 buffer was stimulated by 10-50 μM albumin but inhibited by higher concentrations. However, albumin stimulated the oxidation of LDL proteins to carbonyl derivatives at all concentrations examined in both buffers. Conversion of LDL to MDA in bicarbonate/CO2 buffer was greatly stimulated by ADP, ATP, and EDTA but only when EDTA was added at a concentration equal to that of iron. At higher than stoichiometric concentrations, EDTA prevented oxidation of LDL. Results of these studies suggest that interactions between bicarbonate and iron or heme derivatives leads to complexes with redox potentials that favor the generation of reactive oxygen species and/or to the generation of highly reactive CO2 anion or bicarbonate radical that facilitates LDL oxidation. Freely available online through the PNAS open access option.Abbreviations: LDL, low-density lipoprotein; MDA, malondialdehyde; MetO, methionine sulfoxide.

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

International Nuclear Information System (INIS)

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

2010-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-05-15

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

Immiscible iron- and silica-rich melt in basalt petrogenesis documented in the Skaergaard intrusion

DEFF Research Database (Denmark)

Jakobsen, Jakob Kløve; Veksler, Ilya; Tegner, Christian

2005-01-01

colored type contains 30.9 6 4.2 wt% FeOt and 40.7 6 3.6 wt% SiO2, whereas the light colored type contains 8.6 6 5.9 wt% FeOt and 65.6 6 7.3 wt% SiO2. Similar light colored melt inclusions in olivine and fine grained dark and light colored interstitial pockets also give evidence of crystallization from......Silicate liquid immiscibility in basalt petrogenesis is a contentious issue. Immiscible iron and silica-rich liquids were reported in melt inclusions of lunar basalt and in groundmass glasses of terrestrial volcanics. In fully crystallized plutonic rocks, however, silicate liquid immiscibility has...

Sodium aluminum-iron phosphate glass-ceramics for immobilization of lanthanide oxide wastes from pyrochemical reprocessing of spent nuclear fuel

Science.gov (United States)

Stefanovsky, S. V.; Stefanovsky, O. I.; Kadyko, M. I.; Nikonov, B. S.

2018-03-01

Sodium aluminum (iron) phosphate glass ceramics containing of up to 20 wt.% rare earth (RE) oxides simulating pyroprocessing waste were produced by melting at 1250 °C followed by either quenching or slow cooling to room temperature. The iron-free glass-ceramics were composed of major glass and minor phosphotridymite and monazite. The iron-bearing glass-ceramics were composed of major glass and minor monazite and Na-Al-Fe orthophosphate at low waste loadings (5-10 wt.%) and major orthophosphate and minor monazite as well as interstitial glass at high waste loadings (15-20 wt.%). Slowly cooled samples contained higher amount of crystalline phases than quenched ones. Monazite is major phase for REs. Leach rates from the materials of major elements (Na, Al, Fe, P) are 10-5-10-7 g cm-2 d-1, RE elements - lower than 10-5 g cm-2 d-1.

Study of interaction of uranium, plutonium and rare earth fluorides with some metal oxides in fluoric salt melts

International Nuclear Information System (INIS)

Gorbunov, V.F.; Novoselov, G.P.; Ulanov, S.A.

1976-01-01

Interaction of plutonium, uranium, and rare-earth elements (REE) fluorides with aluminium and calcium oxides in melts of eutectic mixture LiF-NaF has been studied at 800 deg C by X-ray diffraction method. It has been shown that tetravalent uranium and plutonium are coprecipitated by oxides as a solid solution UO 2 -PuO 2 . Trivalent plutonium in fluorides melts in not precipitated in the presence of tetravalent uranium which can be used for their separation. REE are precipitated from a salt melt by calcium oxide and are not precipitated by aluminium oxide. Thus, aluminium oxide in a selective precipitator for uranium and plutonium in presence of REE. Addition of aluminium fluoride retains trivalent plutonium and REE in a salt melt in presence of Ca and Al oxides. The mechanism of interacting plutonium and REE trifluorides with metal oxides in fluoride melts has been considered

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

Science.gov (United States)

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

2011-11-01

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

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

Science.gov (United States)

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

2015-03-06

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

Composition of MBE-grown iron oxide films

NARCIS (Netherlands)

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

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

Body iron is a contributor to oxidative damage of DNA

DEFF Research Database (Denmark)

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

2007-01-01

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

Iron Oxide as an MRI Contrast Agent for Cell Tracking

Science.gov (United States)

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

2015-01-01

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

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

OpenAIRE

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

2012-01-01

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

Application of metal oxide refractories for melting and casting reactive metals

International Nuclear Information System (INIS)

Jessen, N.C. Jr.; Holcombe, C.E. Jr.; Townsend, A.B.

1979-01-01

Extensive investigations have been conducted to develop metal oxide refractories for containment of molten uranium and uranium alloys. Since uranium and uranium alloys are readily susceptable to the formation of complex oxides, carbides, nitrides, intermetallic compounds, and suboxide reactions, severe problems exist for the production of quality castings. These contamination reactions are dependent on temperature, pressure, and molten metal interfacial reactions. The need for high purity metals to meet specification repeatedly has resulted in the development of improved metal oxide refractories and sophisticated furnace controls. Applications of Y 2 O 3 for use as a crucible and mold coating, precision molds and cores, and high temperature castable ceramics are discussed. Experimental results on melt impurity levels, thermal controls during melting, surface interactions and casting quality are presented

DLVO and XDLVO calculations for bacteriophage MS2 adhesion to iron oxide particles.

Science.gov (United States)

Park, Jeong-Ann; Kim, Song-Bae

2015-10-01

In this study, batch experiments were performed to examine the adhesion of bacteriophage MS2 to three iron oxide particles (IOP1, IOP2 and IOP3) with different particle properties. The characteristics of MS2 and iron oxides were analyzed using various techniques to construct the classical DLVO and XDLVO potential energy profiles between MS2 and iron oxides. X-ray diffractometry peaks indicated that IOP1 was mainly composed of maghemite (γ-Fe2O3), but also contained some goethite (α-FeOOH). IOP2 was composed of hematite (α-Fe2O3) and IOP3 was composed of iron (Fe), magnetite (Fe3O4) and iron oxide (FeO). Transmission electron microscope images showed that the primary particle size of IOP1 (γ-Fe2O3) was 12.3±4.1nm. IOP2 and IOP3 had primary particle sizes of 167±35nm and 484±192nm, respectively. A surface angle analyzer demonstrated that water contact angles of IOP1, IOP2, IOP3 and MS2 were 44.83, 64.00, 34.33 and 33.00°, respectively. A vibrating sample magnetometer showed that the magnetic saturations of IOP1, IOP2 and IOP3 were 176.87, 17.02 and 946.85kA/m, respectively. Surface potentials measured in artificial ground water (AGW; 0.075mM CaCl2, 0.082mM MgCl2, 0.051mM KCl, and 1.5mM NaHCO3; pH7.6) indicated that iron oxides and MS2 were negatively charged in AGW (IOP1=-0.0185V; IOP2=-0.0194V; IOP3=-0.0301V; MS2=-0.0245V). Batch experiments demonstrated that MS2 adhesion to iron oxides was favorable in the order of IOP1>IOP2>IOP3. This tendency was well predicted by the classical DLVO model. In the DLVO calculations, both the sphere-plate and sphere-sphere geometries predicted the same trend of MS2 adhesion to iron oxides. Additionally, noticeable differences were not found between the DLVO and XDLVO interaction energy profiles, indicating that hydrophobic interactions did not play a major role; electrostatic interactions, however, did influence MS2 adhesion to iron oxides. Furthermore, the aggregation of iron oxides was investigated with a modified XDLVO

Chitosan-iron oxide nanocomposite based electrochemical aptasensor for determination of malathion

Energy Technology Data Exchange (ETDEWEB)

Prabhakar, Nirmal, E-mail: nirmalprabhakar@gmail.com; Thakur, Himkusha; Bharti, Anu; Kaur, Navpreet

2016-10-05

An electrochemical aptasensor based on chitosan-iron oxide nanocomposite (CHIT-IO) film deposited on fluorine tin Oxide (FTO) was developed for the detection of malathion. Iron oxide nanoparticles were prepared by co-precipitation method and characterized by Transmission electron microscopy and UV–Visible spectroscopy. The biotinylated DNA aptamer sequence specific to the malathion was immobilized onto the iron oxide doped-chitosan/FTO electrode by using streptavidin as linking molecule. Various characterization studies like Field Emission-Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Electrochemical studies were performed to attest the successful fabrication of bioelectrodes. Experimental parameters like aptamer concentration, response time, stability of electrode and reusability studies were optimized. Aptamer immobilized chitosan-iron oxide nanocomposite (APT/SA/CHIT-IO/FTO) bioelectrodes exhibited LOD of about 0.001 ng/mL within 15 min and spike-in studies revealed about 80–92% recovery of malathion from the lettuce leaves and soil sample. - Highlights: • An electrochemical aptasensor for the detection of Malathion has been developed. • Chitosan-iron oxide NP deposited FTO sheets provides platform for aptamer immobilization. • Aptasensor has efficiency to detect malathion upto 0.001 ng/mL within 15 min.

Doxorubicin loaded PVA coated iron oxide nanoparticles for targeted drug delivery

International Nuclear Information System (INIS)

Kayal, S.; Ramanujan, R.V.

2010-01-01

Magnetic drug targeting is a drug delivery system that can be used in locoregional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by coprecipitation of iron oxide followed by coating with polyvinyl alcohol (PVA). Characterization was carried out using X-ray diffraction, TEM, TGA, FTIR and VSM techniques. The magnetic core of the carriers was magnetite (Fe 3 O 4 ), with average size of 10 nm. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. The amount of PVA bound to the iron oxide nanoparticles were estimated by thermogravimetric analysis (TGA) and the attachment of PVA to the iron oxide nanoparticles was confirmed by FTIR analysis. Doxorubicin (DOX) drug loading and release profiles of PVA coated iron oxide nanoparticles showed that up to 45% of adsorbed drug was released in 80 h, the drug release followed the Fickian diffusion-controlled process. The binding of DOX to the PVA was confirmed by FTIR analysis. The present findings show that DOX loaded PVA coated iron oxide nanoparticles are promising for magnetically targeted drug delivery.

Iron/iron oxide core-shell nanoclusters for biomedical applications

International Nuclear Information System (INIS)

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

2006-01-01

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

Chemically durable iron phosphate glasses for vitrifying sodium bearing waste (SBW) using conventional and cold crucible induction melting (CCIM) techniques

Energy Technology Data Exchange (ETDEWEB)

Kim, C.W. E-mail: cheol@umr.edu; Ray, C.S.; Zhu, D.; Day, D.E.; Gombert, D.; Aloy, A.; Mogus-Milankovic, A.; Karabulut, M

2003-11-01

A simulated sodium bearing waste (SBW) was successfully vitrified in iron phosphate glasses (IPG) at a maximum waste loading of 40 wt% using conventional and cold crucible induction melting (CCIM) techniques. No sulfate segregation or crystalline phases were detectable in the IPG when examined by SEM and XRD. The IPG wasteforms containing 40 wt% SBW satisfy current DOE requirements for aqueous chemical durability as evaluated from their bulk dissolution rate (D{sub R}), product consistency test, and vapor hydration test. The fluid IPG wasteforms can be melted at a relatively low temperature (1000 deg. C) and for short times (<6 h). These properties combined with a significantly higher waste loading, and the feasibility of CCIM melting offer considerable savings in time, energy, and cost for vitrifying the SBW stored at the Idaho National Engineering and Environmental Laboratory in iron phosphate glasses.

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

Science.gov (United States)

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

2016-01-01

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

Body iron is a contributor to oxidative damage of DNA

DEFF Research Database (Denmark)

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

2007-01-01

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

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

African Journals Online (AJOL)

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

Melting in super-earths.

Science.gov (United States)

Stixrude, Lars

2014-04-28

We examine the possible extent of melting in rock-iron super-earths, focusing on those in the habitable zone. We consider the energetics of accretion and core formation, the timescale of cooling and its dependence on viscosity and partial melting, thermal regulation via the temperature dependence of viscosity, and the melting curves of rock and iron components at the ultra-high pressures characteristic of super-earths. We find that the efficiency of kinetic energy deposition during accretion increases with planetary mass; considering the likely role of giant impacts and core formation, we find that super-earths probably complete their accretionary phase in an entirely molten state. Considerations of thermal regulation lead us to propose model temperature profiles of super-earths that are controlled by silicate melting. We estimate melting curves of iron and rock components up to the extreme pressures characteristic of super-earth interiors based on existing experimental and ab initio results and scaling laws. We construct super-earth thermal models by solving the equations of mass conservation and hydrostatic equilibrium, together with equations of state of rock and iron components. We set the potential temperature at the core-mantle boundary and at the surface to the local silicate melting temperature. We find that ancient (∼4 Gyr) super-earths may be partially molten at the top and bottom of their mantles, and that mantle convection is sufficiently vigorous to sustain dynamo action over the whole range of super-earth masses.

Iron oxides and their applications in catalytic processes: a review

OpenAIRE

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

2013-01-01

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

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

Science.gov (United States)

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

2009-06-01

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

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

Czech Academy of Sciences Publication Activity Database

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

2011-01-01

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

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

Science.gov (United States)

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

2014-03-01

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

Mapping of mechanical properties of cast iron melts using non-destructive structuroscopy

Directory of Open Access Journals (Sweden)

J. Dočekal

2008-07-01

Full Text Available The contribution is focused on mapping of mechanical properties using methods of non-destructive structuroscopy of cast irons, which are a result of research at TU of Liberec and Institute of Physics of ASCR. Investigated samples become from melts of FOCAM s.r.o Olomouc Foundry shop. It compares data of mechanical properties obtained using ultrasound method with data from magnetic spot method and MAT. These are interpreted by mathematic models applicable in practice. In the following it concerns to derivation of loading tensile curve method, which can be used to obtain yield and fatigue strength limits even for cast irons with flake graphite. In spite of promising results reported by literature the experiments are bothered with error. This method can be applied to structure checking both before casting and at vendor inspection of castings.

Red Dawn: Characterizing Iron Oxide Minerals in Atmospheric Dust

Science.gov (United States)

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

2012-12-01

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

Spent oxide fuel regeneration by crystallization in molybdate melts

International Nuclear Information System (INIS)

Ustinov, O.A.; Sukhanov, L.P.; Yakunin, S.A.

2006-01-01

Paper describes a procedure to regenerate spent oxide fuel by its crystallization in molybdate melts. Paper presents the process procedures to regenerate spent fuel of both fast and thermal neutron reactors. One analyzes the advantages of the elaborated procedure [ru

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

Directory of Open Access Journals (Sweden)

S Mazaherinia

2011-02-01

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

Chromium Elimination from Water by use of Iron Oxide Nanoparticles Absorbents

Directory of Open Access Journals (Sweden)

S Shokraei

2014-09-01

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

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

International Nuclear Information System (INIS)

Li Dengxin; Gao Guolong; Meng Fanling; Ji Chong

2008-01-01

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

Trapped Melt in IIIAB Irons: Solid/Liquid Elemental Partitioning During the Fractionation of the IIIAB Magma

Science.gov (United States)

Wasson, John T.

1999-01-01

Group IIIAB, the largest iron-meteorite group, shows compositional trends (including a three-order-of-magnitude It concentration range) indicating that it formed by fractional crystallization of a metallic magma. Because about 200 irons are available, and all degrees of crystallization are well represented, IIIAB offers an excellent set of samples for the study of crystallization at all depths of the asteroidal core. On log-log Ir-Au, and Ir-As diagrams IIIAB forms a broad band; the breadth represents real meteorite-to-meteorite variations, far outside experimental or sampling uncertainties. A successful model must explain the width of this band; I suggest that it mainly resulted from the trapping of parental magma within the crystallizing solid. Because S is essentially insoluble in metal, the abundance of FeS is a measure of the fraction of trapped liquid. The trapped-melt model is supported by the observation that irons having higher S contents plot closer to the inferred composition of the magmatic parental liquid. The lowest S values are found in the irons occupying the left envelope of the IIIAB Ir-Au or Ir-As compositional fields, thus it is this set of irons that should be interpreted as the solid products of a fractionating magma. This simplifies the modeling of the crystallization process and allows inferences regarding the distribution ratios for other elements in the evolved IIIAB system. The large (multiton) Cape York irons show wide variations in their trapped-melt fractions; their compositions seem best understood in terms of a low initial S content of the IIIAB magma, about 20 mg/g. The inferred initial IIIAB distribution coefficient for Ir, 4.6, is much higher than published values based on laboratory studies of low-S systems; I suggest that low-S (and low-P) partition-ratio measurements tend to err in the direction of unity. In IIIAB distribution coefficients for Au, As, and Ni were still < 1 when the most evolved IIIAB irons formed, another

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

Science.gov (United States)

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

2017-01-23

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

Electrochemical reduction of nitroaromatic compounds by single sheet iron oxide coated electrodes

Energy Technology Data Exchange (ETDEWEB)

Huang, Li-Zhi, E-mail: lizhi@plen.ku.dk [Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK–1871 Frederiksberg C (Denmark); Hansen, Hans Christian B. [Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK–1871 Frederiksberg C (Denmark); Bjerrum, Morten Jannik [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK–2100 København Ø (Denmark)

2016-04-05

Highlights: • Composite layers of single sheet iron oxides were coated on indium tin oxide electrodes. • Single sheet iron oxide is an electro-catalyst for reduction of nitroaromatic compounds in aqueous solution. • The reduction is well explained by a diffusion layer model. • The charge properties of the nitrophenols have an important influence on reduction. • Low-cost iron oxide based materials are promising electro-catalyst for water treatment. - Abstract: Nitroaromatic compounds are substantial hazard to the environment and to the supply of clean drinking water. We report here the successful reduction of nitroaromatic compounds by use of iron oxide coated electrodes, and demonstrate that single sheet iron oxides formed from layered iron(II)-iron(III) hydroxides have unusual electrocatalytic reactivity. Electrodes were produced by coating of single sheet iron oxides on indium tin oxide electrodes. A reduction current density of 10 to 30 μA cm{sup −2} was observed in stirred aqueous solution at pH 7 with concentrations of 25 to 400 μM of the nitroaromatic compound at a potential of −0.7 V vs. SHE. Fast mass transfer favors the initial reduction of the nitroaromatic compound which is well explained by a diffusion layer model. Reduction was found to comprise two consecutive reactions: a fast four-electron first-order reduction of the nitro-group to the hydroxylamine-intermediate (rate constant = 0.28 h{sup −1}) followed by a slower two-electron zero-order reduction resulting in the final amino product (rate constant = 6.9 μM h{sup −1}). The zero-order of the latter reduction was attributed to saturation of the electrode surface with hydroxylamine-intermediates which have a more negative half-wave potential than the parent compound. For reduction of nitroaromatic compounds, the SSI electrode is found superior to metal electrodes due to low cost and high stability, and superior to carbon-based electrodes in terms of high coulombic efficiency and

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

Science.gov (United States)

Shanker, Uma; Singh, Gurinder; Kamaluddin

2013-06-01

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

Microwave-Assisted Combustion Synthesis of Nano Iron Oxide/Iron-Coated Activated Carbon, Anthracite, Cellulose Fiber, and Silica, with Arsenic Adsorption Studies

Directory of Open Access Journals (Sweden)

Mallikarjuna N. Nadagouda

2011-01-01

Full Text Available Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber, and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was completed within a few minutes. The method used no additional fuel and nitrate, which is present in the precursor itself, to drive the reaction. The obtained samples were then characterized with X-ray mapping, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDS, selected area diffraction pattern (SAED, transmission electron microscopy (TEM, X-ray diffraction (XRD, and inductively coupled plasma (ICP spectroscopy. The size of the iron oxide/iron nanoparticle-coated activated carbon, anthracite, cellulose fiber, and silica samples were found to be in the nano range (50–400 nm. The iron oxide/iron nanoparticles mostly crystallized into cubic symmetry which was confirmed by SAED. The XRD pattern indicated that iron oxide/iron nano particles existed in four major phases. That is, γ-Fe2O3, α-Fe2O3, Fe3O4, and Fe. These iron-coated activated carbon, anthracite, cellulose fiber, and silica samples were tested for arsenic adsorption through batch experiments, revealing that few samples had significant arsenic adsorption.

Cast irons

CERN Document Server

1996-01-01

Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

Viscosity and electrical conductivity of glass melts as a function of waste composition

International Nuclear Information System (INIS)

Plodinec, M.J.; Wiley, J.R.

1979-01-01

Radioactive waste at the Savannah River Plant contains high concentrations of nonradioactive compounds of iron and aluminum. Simulated waste compositions containing varying ratios of iron to aluminum were added to glass melts to determine the effect on the melt properties. Waste containing high-aluminum increased the melt viscosity, but waste containing high-iron reduced the melt viscosity. Aluminum and iron both reduced the melt conductivity

A novel thermal decomposition approach for the synthesis of silica-iron oxide core–shell nanoparticles

International Nuclear Information System (INIS)

Kishore, P.N.R.; Jeevanandam, P.

2012-01-01

Highlights: ► Silica-iron oxide core–shell nanoparticles have been synthesized by a novel thermal decomposition approach. ► The silica-iron oxide core–shell nanoparticles are superparamagnetic at room temperature. ► The silica-iron oxide core–shell nanoparticles serve as good photocatalyst for the degradation of Rhodamine B. - Abstract: A simple thermal decomposition approach for the synthesis of magnetic nanoparticles consisting of silica as core and iron oxide nanoparticles as shell has been reported. The iron oxide nanoparticles were deposited on the silica spheres (mean diameter = 244 ± 13 nm) by the thermal decomposition of iron (III) acetylacetonate, in diphenyl ether, in the presence of SiO 2 . The core–shell nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, field emission-scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy, diffuse reflectance spectroscopy, and magnetic measurements. The results confirm the presence of iron oxide nanoparticles on the silica core. The core–shell nanoparticles are superparamagnetic at room temperature indicating the presence of iron oxide nanoparticles on silica. The core–shell nanoparticles have been demonstrated as good photocatalyst for the degradation of Rhodamine B.

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

Science.gov (United States)

Gharehaghaji, Nahideh; Divband, Baharak; Zareei, Loghman

2018-06-01

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

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

Directory of Open Access Journals (Sweden)

C. L. Popa

2015-01-01

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

Iron Oxide Minerals in Atmospheric Dust and Source Sediments-Studies of Types and Properties to Assess Environmental Effects

Science.gov (United States)

Reynolds, R. L.; Goldstein, H. L.; Moskowitz, B. M.; Till, J. L.; Flagg, C.; Kokaly, R. F.; Munson, S.; Landry, C.; Lawrence, C. R.; Hiza, M. M.; D'Odorico, P.; Painter, T. H.

2011-12-01

Ferric oxide minerals in atmospheric dust can influence atmospheric temperatures, accelerate melting of snow and ice, stimulate marine phytoplankton productivity, and impact human health. Such effects vary depending on iron mineral type, size, surface area, and solubility. Generally, the presence of ferric oxides in dust is seen in the red, orange, or yellow hues of plumes that originate in North Africa, central and southwest Asia, South America, western North America, and Australia. Despite their global importance, these minerals in source sediments, atmospheric dust, and downwind aeolian deposits remain poorly described with respect to specific mineralogy, particle size and surface area, or presence in far-traveled aerosol compounds. The types and properties of iron minerals in atmospheric dust can be better understood using techniques of rock magnetism (measurements at 5-300 K), Mössbauer and high-resolution visible and near-infrared reflectance spectroscopy; chemical reactivity of iron oxide phases; and electron microscopy for observing directly the ferric oxide coatings and particles. These studies can elucidate the diverse environmental effects of iron oxides in dust and can help to identify dust-source areas. Dust-source sediments from the North American Great Basin and Colorado Plateau deserts and the Kalahari Desert, southern Africa, were used to compare average reflectance values with a magnetic parameter (hard isothermal remanent magnetization, HIRM) for ferric oxide abundance. Lower reflectance values correspond strongly with higher HIRM values, indicating that ferric oxides (hematite or goethite, or both) contribute to absorption of solar radiation in these sediments. Dust deposited to snow cover of the San Juan Mountains (Colorado) and Wasatch Mountains (Utah) was used to characterize dust composition compared with properties of sediments exposed in source-areas identified from satellite retrievals. Results from multiple methods indicate that

Thermosensitive liposomes entrapping iron oxide nanoparticles for controllable drug release

International Nuclear Information System (INIS)

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

2009-01-01

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

Microbial Oxidation of Iron Sulfides in Anaerobic Environments

DEFF Research Database (Denmark)

Vaclavkova, Sarka

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

Recovery of iron oxide from coal fly ash

Science.gov (United States)

Dobbins, Michael S.; Murtha, Marlyn J.

1983-05-31

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

Oxide Dispersion Strengthened Iron Aluminide by CVD Coated Powders

Energy Technology Data Exchange (ETDEWEB)

Asit Biswas Andrew J. Sherman

2006-09-25

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

Heterogeneous biomimetic catalysis using iron porphyrin for cyclohexane oxidation promoted by chitosan

Energy Technology Data Exchange (ETDEWEB)

Huang, Guan, E-mail: huangg66@126.com; Liu, Yao; Cai, Jing Li; Chen, Xiang Feng; Zhao, Shu Kai; Guo, Yong An; Wei, Su Juan; Li, Xu

2017-04-30

Graphical abstract: A biomimetic catalyst of iron-tetrakis(4-sulfonatophenyl)porphyrin immobilized on powdered chitosan achieves efficient cyclohexane oxidation with high ketone and alcohol yields. - Highlights: • Fe (TPPS)/pd-CTS is an excellent catalyst for cyclohexane oxidation. • Amino ligation alters the electron cloud density around the iron cation. • Amino coordination likely reduces the activation energy of Fe (TPPS). • The catalyst achieved 22.9 mol% yields of cyclohexanone and cyclohexanol. - Abstract: This study investigates how ligands modulate metalloporphyrin activity with the goal of producing a practical biomimetic catalyst for use in the chemical industry. We immobilized iron porphyrinate [iron-tetrakis-(4-sulfonatophenyl)-porphyrin; Fe(III) (TPPS)] on powdered chitosan (pd-CTS) to form an immobilized catalyst Fe(III) (TPPS)/pd-CTS, which was characterized using modern spectroscopic techniques and used for catalytic oxidation of cyclohexane with O{sub 2}. Amino coordination to iron porphyrin in Fe(III) (TPPS)/pd-CTS altered the electron cloud density around the iron cation, probably by reducing the activation energy of Fe(III) (TPPS) and raising the reactivity of the iron ion catalytic center, thereby improving the catalytic efficiency. One milligram of Fe(III) (TPPS) catalyst can be reused three times for the oxidation reaction to yield an average of 22.9 mol% of cyclohexanone and cyclohexanol.

Reaction of metal oxides with molten mixtures NaPO3+NaCl

International Nuclear Information System (INIS)

Kovarskaya, E.N.; Mityakhina, V.S.; Rodionov, Yu.I.; Silin, M.Yu.

1988-01-01

By methods of solubility determination and paper chromatography it is shown, that Fe 2 O 3 solution in NaPO 3 +NaCl melts in the air relizes due to its chemical interaction with solvent resulting in formation of iron and sodium binary di- and monophosphates depending on melt-solvent initial composition, its attainment of equilibrium state and experiment temperature. It is established, that oxides increased solubility in melts with NaCl initial content ∼30 mol.% is specified by sodium tri- and tricyclophosphates presence in the melts. On this basis of NGR-spectroscopy data the presence of iron, europium, tin and sodium binary di- and monophosphates in some chloride-polyphosphate melts is confirmed

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

International Nuclear Information System (INIS)

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

2012-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-10-15

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

Oxidative stability of a heme iron-fortified bakery product: Effectiveness of ascorbyl palmitate and co-spray-drying of heme iron with calcium caseinate.

Science.gov (United States)

Alemán, Mercedes; Bou, Ricard; Tres, Alba; Polo, Javier; Codony, Rafael; Guardiola, Francesc

2016-04-01

Fortification of food products with iron is a common strategy to prevent or overcome iron deficiency. However, any form of iron is a pro-oxidant and its addition will cause off-flavours and reduce a product's shelf life. A highly bioavailable heme iron ingredient was selected to fortify a chocolate cream used to fill sandwich-type cookies. Two different strategies were assessed for avoiding the heme iron catalytic effect on lipid oxidation: ascorbyl palmitate addition and co-spray-drying of heme iron with calcium caseinate. Oxidation development and sensory acceptability were monitored in the cookies over one-year of storage at room temperature in the dark. The addition of ascorbyl palmitate provided protection against oxidation and loss of tocopherols and tocotrienols during the preparation of cookies. In general, ascorbyl palmitate, either alone or in combination with the co-spray-dried heme iron, prevented primary oxidation and hexanal formation during storage. The combination of both strategies resulted in cookies that were acceptable from a sensory point of view after 1year of storage. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

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

1989-01-20

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

Adsorption of arsenic(V) by iron-oxide-coated diatomite (IOCD).

Science.gov (United States)

Pan, Yi-Fong; Chiou, Cary T; Lin, Tsair-Fuh

2010-09-01

PURPOSES AND AIMS: Economically efficient methods for removing arsenic from the drinking water supply are urgently needed in many parts of the world. Iron oxides are known to have a strong affinity for arsenic in water. However, they are commonly present in the forms of fine powder or floc, which limits their utility in water treatment. In this study, a novel granular adsorbent, iron-oxide-coated diatomite (IOCD), was developed and examined for its adsorption of arsenic from water. An industrial-grade diatomite was used as the iron oxide support. The diatomite was first acidified and dried and then coated with iron oxide up to five times. The prepared IOCD samples were characterized for their morphology, composition, elemental content, and crystal properties by various instruments. Experiments of equilibrium and kinetic adsorption of As(V) on IOCD were conducted using 0.1- and 2-L polyethylene bottles, respectively, at different pH and temperatures. Iron oxide (alpha-Fe(2)O(3) hematite) coated onto diatomite greatly improves (by about 30 times) the adsorption of As(V) from water by IOCD as compared to using raw diatomite. This improvement was attributed to increases in both surface affinity and surface area of the IOCD. The surface area of IOCD increased to an optimal value. However, as the IOCD surface area (93 m(2)/g) was only 45% higher than that of raw diatomite (51 m(2)/g), the enhanced As(V) adsorption resulted primarily from the enhanced association of negatively charged As(V) ions with the partial positive surface charge of the iron oxide. The As(V) adsorption decreased when the solution pH was increased from 3.5 to 9.5, as expected from the partial charge interaction between As(V) and IOCD. The adsorption data at pH 5.5 and 7.5 could be well fitted to the Freundlich equation. A moderately high exothermic heat was observed for the As(V) adsorption, with the calculated molar isosteric heat ranging from -4 to -9 kcal/mol. The observed heats fall between those

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

NARCIS (Netherlands)

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

2011-01-01

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

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

International Nuclear Information System (INIS)

Olivier, Francoise

1972-01-01

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

Thermodynamic Characterization of Iron Oxide-Aqueous Fe(2+) Redox Couples.

Science.gov (United States)

Gorski, Christopher A; Edwards, Rebecca; Sander, Michael; Hofstetter, Thomas B; Stewart, Sydney M

2016-08-16

Iron is present in virtually all terrestrial and aquatic environments, where it participates in redox reactions with surrounding metals, organic compounds, contaminants, and microorganisms. The rates and extent of these redox reactions strongly depend on the speciation of the Fe2+ and Fe3+ phases, although the underlying reasons remain unclear. In particular, numerous studies have observed that Fe2+ associated with iron oxide surfaces (i.e., oxide-associated Fe2+) often reduces oxidized contaminants much faster than aqueous Fe2+ alone. Here, we tested two hypotheses related to this observation by determining if solutions containing two commonly studied iron oxides—hematite and goethite—and aqueous Fe2+ reached thermodynamic equilibrium over the course of a day. We measured reduction potential (EH) values in solutions containing these oxides at different pH values and aqueous Fe2+ concentrations using mediated potentiometry. This analysis yielded standard reduction potential (EH0) values of 768 ± 1 mV for the aqueous Fe2+–goethite redox couple and 769 ± 2 mV for the aqueous Fe2+–hematite redox couple. These values were in excellent agreement with those calculated from existing thermodynamic data, and the data could be explained by the presence of an iron oxide lowering EH values of aqueous Fe3+/Fe2+ redox couples.

Synthesis engineering of iron oxide raspberry-shaped nanostructures.

Science.gov (United States)

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

2017-01-07

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

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

Science.gov (United States)

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

2015-01-01

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

Iron from melting glaciers fuels phytoplankton blooms in the Amundsen Sea (Southern Ocean): Phytoplankton characteristics and productivity

NARCIS (Netherlands)

Alderkamp, A.C.; Mills, M.M.; van Dijken, G.L.; Laan, P.; Thuróczy, C.-E.; Gerringa, L.J.A.; de Baar, H.J.W.; Payne, C.D.; Visser, R.J.W.; Buma, A.G.J.; Arrigo, K.R.

2012-01-01

The phytoplankton community composition and productivity in waters of the Amundsen Sea and surrounding sea ice zone were characterized with respect to iron (Fe) input from melting glaciers. High Fe input from glaciers such as the Pine Island Glacier, and the Dotson and Crosson ice shelves resulted

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

Science.gov (United States)

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

2015-11-03

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

REACTION PRODUCTS AND CORROSION OF MOLYBDENUM ELECTRODE IN GLASS MELT CONTAINING ANTIMONY OXIDES AND SODIUM SULFATE

Directory of Open Access Journals (Sweden)

JIŘÍ MATĚJ

2012-09-01

Full Text Available The products on the interface of a molybdenum electrode and glass melt were investigated primarily at 1400°C in three model glass melts without ingredients, with 1 % Sb2O3 and with 1 % Sb2O3 and 0.5 % SO3 (wt. %, both under and without load by alternating current. Corrosion of the molybdenum electrode in glass melt without AC load is higher by one order of magnitude if antimony oxides are present. The corrosion continues to increase if sulfate is present in addition to antimony oxides. Isolated antimony droplets largely occur on the electrode-glass melt interface, and numerous droplets are also dissipated in the surrounding glass if only antimony oxides are present in the glass melt. A comparatively continuous layer of antimony occurs on the interface if SO3 is also present, antimony being always in contact with molybdenum sulfide. Almost no antimony droplets are dissipated in the glass melt. The total amount of precipitated antimony also increases. The presence of sulfide on the interface likely facilitates antimony precipitation. The reaction of molybdenum with antimony oxides is inhibited in sites covered by an antimony layer. The composition of sulfide layers formed at 1400°C approximates that of Mo2S3. At 1100°C, the sulfide composition approximates that of MoS4. Corrosion multiplies in the glass melt without additions through the effect of AC current, most molybdenum being separated in the form of metallic particles. Corrosion also increases in the glass melt containing antimony oxides. This is due to increased corrosion in the neighborhood of the separated antimony droplets. This mechanism also results in the loosening of molybdenum particles. The amount of precipitated antimony also increases through the effect of the AC current. AC exerts no appreciable effect on either corrosion, the character of the electrode-glass interface, or antimony precipitation in the glass melt containing SO3.

Iron oxide nanoparticles stabilized inside highly ordered ...

Indian Academy of Sciences (India)

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

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

Directory of Open Access Journals (Sweden)

Saba Naqvi

2010-11-01

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

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

Directory of Open Access Journals (Sweden)

Alberto Vasconcellos Inda

2013-02-01

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

Iron metal production in silicate melts through the direct reduction of Fe/II/ by Ti/III/, Cr/II/, and Eu/II/. [in lunar basalts

Science.gov (United States)

Schreiber, H. D.; Balazs, G. B.; Shaffer, A. P.; Jamison, P. L.

1982-01-01

The production of metallic iron in silicate melts by chemical reactions of Ti(3+), Cr(2+), and Eu(2+) with Fe(2+) is demonstrated under experimental conditions in a simplified basaltic liquid. These reactions form a basis for interpreting the role of isochemical valency exchange models in explanations for the reduced nature of lunar basalts. The redox couples are individually investigated in the silicate melt to ascertain reference redox ratios that are independent of mutual interactions. These studies also provide calibrations of spectral absorptions of the Fe(2+) and Ti(2+) species in these glasses. Subsequent spectrophotometric analyses of Fe(2+) and Ti(2+) in glasses doped with both iron and titanium and of Fe(2+) in glasses doped with either iron and chromium or iron and europium ascertain the degree of mutual interactions in these dual-doped glasses.

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

Science.gov (United States)

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

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

DEFF Research Database (Denmark)

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

2018-01-01

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

In situ reduction of as-prepared γ-Iron Oxide Nanoparticles

DEFF Research Database (Denmark)

Garbus, Pelle Gorm; Ahlburg, Jakob; Christensen, Mogens

-ray diffraction measurement. The as-prepared maghemite nanoparticles were synthesized by the continuous decomposition of solutes in supercritical hydrothermal flow synthesis [3, 4]. The reagent used was ferric ammonium citrate (C6H8O7•xFe(III)•yNH3) that under hydrothermal flow synthesis decomposes into the γ......-iron oxide Fe2O3. The reduction of maghemite to body centered cubic (BCC) iron does not go through a detectable intermediate state.1.Jensen, K.M., et al., Mechanisms for iron oxide formation under hydrothermal conditions: an in situ total scattering study. ACS nano, 2014. 8(10): p. 10704-10714.2.Andersen, H...

Review of the Evidence from Epidemiology, Toxicology, and Lung Bioavailability on the Carcinogenicity of Inhaled Iron Oxide Particulates.

Science.gov (United States)

Pease, Camilla; Rücker, Thomas; Birk, Thomas

2016-03-21

Since the iron-age and throughout the industrial age, humans have been exposed to iron oxides. Here, we review the evidence from epidemiology, toxicology, and lung bioavailability as to whether iron oxides are likely to act as human lung carcinogens. Current evidence suggests that observed lung tumors in rats result from a generic particle overload effect and local inflammation that is rat-specific under the dosing conditions of intratracheal instillation. This mode of action therefore, is not relevant to human exposure. However, there are emerging differences seen in vitro, in cell uptake and cell bioavailability between "bulk" iron oxides and "nano" iron oxides. "Bulk" particulates, as defined here, are those where greater than 70% are >100 nm in diameter. Similarly, "nano" iron oxides are defined in this context as particulates where the majority, usually >95% for pure engineered forms of primary particulates (not agglomerates), fall in the range 1-100 nm in diameter. From the weight of scientific evidence, "bulk" iron oxides are not genotoxic/mutagenic. Recent evidence for "nano" iron oxide is conflicting regarding genotoxic potential, albeit genotoxicity was not observed in an in vivo acute oral dose study, and "nano" iron oxides are considered safe and are being investigated for biomedical uses; there is no specific in vivo genotoxicity study on "nano" iron oxides via inhalation. Some evidence is available that suggests, hypothetically due to the larger surface area of "nano" iron oxide particulates, that toxicity could be exerted via the generation of reactive oxygen species (ROS) in the cell. However, the potential for ROS generation as a basis for explaining rodent tumorigenicity is only apparent if free iron from intracellular "nano" scale iron oxide becomes bioavailable at significant levels inside the cell. This would not be expected from "bulk" iron oxide particulates. Furthermore, human epidemiological evidence from a number of studies suggests that

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

Science.gov (United States)

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

Controlling lipid oxidation via a biomimetic iron chelating active packaging material.

Science.gov (United States)

Tian, Fang; Decker, Eric A; Goddard, Julie M

2013-12-18

Previously, a siderophore-mimetic metal chelating active packaging film was developed by grafting poly(hydroxamic acid) (PHA) from the surface of polypropylene (PP) films. The objective of the current work was to demonstrate the potential applicability of this PP-g-PHA film to control iron-promoted lipid oxidation in food emulsions. The iron chelating activity of this film was investigated, and the surface chemistry and color intensity of films were also analyzed after iron chelation. In comparison to the iron chelating activity in the free Fe(3+) solution, the PP-g-PHA film retained approximately 50 and 30% of its activity in nitrilotriacetic acid (NTA)/Fe(3+) and citric acid/Fe(3+) solutions, respectively (pH 5.0), indicating a strong chelating strength for iron. The ability of PP-g-PHA films to control lipid oxidation was demonstrated in a model emulsion system (pH 3.0). PP-g-PHA films performed even better than ethylenediaminetetraacetic acid (EDTA) in preventing the formation of volatile oxidation products. The particle size and ζ potential results of emulsions indicated that PP-g-PHA films had no adverse effects on the stability of the emulsion system. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis suggested a non-migratory nature of the PP-g-PHA film surface. These results suggest that such biomimetic, non-migratory metal chelating active packaging films have commercial potential in protecting foods against iron-promoted lipid oxidation.

Electrolytic photodissociation of chemical compounds by iron oxide electrodes

Science.gov (United States)

Somorjai, Gabor A.; Leygraf, Christofer H.

1984-01-01

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

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

International Nuclear Information System (INIS)

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

1979-01-01

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

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

DEFF Research Database (Denmark)

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

2013-01-01

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

Size distribution of magnetic iron oxide nanoparticles using Warren-Averbach XRD analysis

Science.gov (United States)

Mahadevan, S.; Behera, S. P.; Gnanaprakash, G.; Jayakumar, T.; Philip, J.; Rao, B. P. C.

2012-07-01

We use the Fourier transform based Warren-Averbach (WA) analysis to separate the contributions of X-ray diffraction (XRD) profile broadening due to crystallite size and microstrain for magnetic iron oxide nanoparticles. The profile shape of the column length distribution, obtained from WA analysis, is used to analyze the shape of the magnetic iron oxide nanoparticles. From the column length distribution, the crystallite size and its distribution are estimated for these nanoparticles which are compared with size distribution obtained from dynamic light scattering measurements. The crystallite size and size distribution of crystallites obtained from WA analysis are explained based on the experimental parameters employed in preparation of these magnetic iron oxide nanoparticles. The variation of volume weighted diameter (Dv, from WA analysis) with saturation magnetization (Ms) fits well to a core shell model wherein it is known that Ms=Mbulk(1-6g/Dv) with Mbulk as bulk magnetization of iron oxide and g as magnetic shell disorder thickness.

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

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Yong-Sang Kim

2017-05-01

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

Criteria for the spreading of oxide melts: Test series miniKATS-1 to -5

International Nuclear Information System (INIS)

Eppinger, B.; Fieg, G.; Massier, H.; Schuetz, W.; Stegmaier, U.; Stern, G.

2001-09-01

In a long series of larger spreading tests with high temperature oxide melts (KATS tests) many parameters have been varied which are influencing the spreading behaviour (viscosity, pouring rate, substratum of spreading surface, presence of water). In spite of an extensive instrumentation using different thermocouples, an infrared camera and several video cameras, only in very few cases the behaviour of the melt front at the very moment of immobilization could be detected in detail. Therefore in the additional miniKATS series five small scale (5 kg) spreading tests with oxide melts have been conducted to investigate the mechanical properties of the spreading front in the moment of immobilization. It turned out that in all cases the bulk of the melt at this moment was still liquid at a temperature close to the initial one. Depending on the initial melt properties two distinct phenomena have been observed which control the immobilization of the melt: the first phenomena is the crust formation at the surface, the crusts at the bottom combined with the crust at the surface of the melt. In the other case the whole melt front was still above the liquid temperature at the moment of immobilization. Here the surface tension was controlling the spreading, it was in balance with the driving gravitational force. In none of the test bulk freezing has been detected. (orig.)

Adsorption of Cadmium Ions from Water on Double-walled Carbon Nanotubes/Iron Oxide Composite

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Karima Seffah

2017-12-01

Full Text Available A new material (DWCNT/iron oxide for heavy metals removal was developed by combining the adsorption features of double-walled carbon nanotubes with the magnetic properties of iron oxides. Batch experiments were applied in order to evaluate adsorption capacity of the DWCNT/iron oxide composite for cadmium ions. The influence of operating parameters such as pH value, amount of adsorbent, initial adsorbate concentration and agitation speed was studied. The adsorption capacity of the DWCNT/iron oxide adsorbent for Cd2+ ions was 20.8 mg g-1, which is at the state of the art. The obtained results revealed that DWCNT/iron oxide composite is a very promising adsorbent for removal of Cd2+ ions from water under natural conditions. The advantage of the magnetic composite is that it can be used as adsorbent for contaminants in water and can be subsequently controlled and removed from the medium by a simple magnetic process.

Experimental research on the characteristics of softening and melting of iron ores as significant factor of influence on gas permeability of blast furnace charge

International Nuclear Information System (INIS)

Branescu, E; Blajan, A O; Constantin, N

2015-01-01

It is widely accepted as a cohesive zone is directly influenced by softening and melting properties of iron ores, preparations (crowded, pellets, which represents about 90%, of the loads with metal furnace intake), or uncooked (raw ores ranked). Important results can be obtained through the study of behavior of ferrous materials at temperatures above 1000 ° C. Starting from research methods presented in the literature, this paper presents itself in carrying out their own laboratory experiments, conducted with the aim of analysing the softening and melting properties of sinter iron cores. (paper)

In situ iron-57 Moessbauer spectroscopic investigations of the effect of titania surface area on the reducibility of titania-supported iron oxide

International Nuclear Information System (INIS)

Berry, F.J.; Du Hongzhang

1990-01-01

Iron-57 Moessbauer spectroscopy has been used to monitor the reducibility in hydrogen of iron oxides supported on titania of differing surface areas. The results show that although Fe 3+ in the iron oxide supported on low surface area titania (11 m 2 g -1 ) is not amenable to facile reduction at low temperatures, complete reduction to metallic iron is achieved by treatment at 600deg C. The data also show that the extent of reduction at elevated temperatures exceeds that which is obtained on similar silica- and alumina-supported systems. Fe 3+ in iron oxide supported on higher surface area titania (50 m 2 g -1 and 240 m 2 g -1 ) is partially reduced in hydrogen at 235deg C to Fe 2+ but fails to attain complete reduction to the metallic state following treatment at 600deg C. The results are related to the different dispersions of iron oxide which can be attained on titania of differing surface area and the consequent interactions between the support and the supported phases. (orig.)

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

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Stephanie Puukila

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

Redox?Reversible Iron Orthovanadate Cathode for Solid Oxide Steam Electrolyzer

OpenAIRE

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

2015-01-01

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

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

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Daniel J. Korchinski

2015-01-01

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

Biocompatibility of chitosan-coated iron oxide nanoparticles with osteoblast cells

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Shi S

2012-10-01

Full Text Available Si-Feng Shi,1 Jing-Fu Jia,2 Xiao-Kui Guo,3 Ya-Ping Zhao,2 De-Sheng Chen,1 Yong-Yuan Guo,1 Tao Cheng,1 Xian-Long Zhang11Department of Orthopedic Surgery, Shanghai Sixth People’s Hospital, School of Medicine, 2School of Chemistry and Chemical Technology, 3Department of Medical Microbiology and Parasitology, School of Medicine, Shanghai Jiao Tong University Shanghai, ChinaBackground: Bone disorders (including osteoporosis, loosening of a prosthesis, and bone infections are of great concern to the medical community and are difficult to cure. Therapies are available to treat such diseases, but all have drawbacks and are not specifically targeted to the site of disease. Chitosan is widely used in the biomedical community, including for orthopedic applications. The aim of the present study was to coat chitosan onto iron oxide nanoparticles and to determine its effect on the proliferation and differentiation of osteoblasts.Methods: Nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, x-ray diffraction, zeta potential, and vibrating sample magnetometry. Uptake of nanoparticles by osteoblasts was studied by transmission electron microscopy and Prussian blue staining. Viability and proliferation of osteoblasts were measured in the presence of uncoated iron oxide magnetic nanoparticles or those coated with chitosan. Lactate dehydrogenase, alkaline phosphatase, total protein synthesis, and extracellular calcium deposition was studied in the presence of the nanoparticles.Results: Chitosan-coated iron oxide nanoparticles enhanced osteoblast proliferation, decreased cell membrane damage, and promoted cell differentiation, as indicated by an increase in alkaline phosphatase and extracellular calcium deposition. Chitosan-coated iron oxide nanoparticles showed good compatibility with osteoblasts.Conclusion: Further research is necessary to optimize magnetic nanoparticles for the treatment of bone disease

High-temperature oxidation of iron, Fe-0.5 wt. % Al and Fe-1 wt% Al alloys in CO2 at atmospheric pressure

International Nuclear Information System (INIS)

Hoogewys, Marcel; Paideassi, Jean.

1978-12-01

The oxidation of several grades of iron (on being a zone-melting grade) in the poly- and monocrystalline forms between 570 and 1150 0 C proceeds along a linear, then a transitory and a parabolic law in correspondence with the growth of wustite possibly covered with magnetite, whereas in the 400-570 0 C range where the parabolic law is rapidly establishing, the scale is entirely formed of magnetite. The oxidation of the two Fe-A1 alloys follows similarly a quasi linear law after a very short linear period. Their weight gains differ only at 10% at most while remaining close to that of iron (except above 570 0 C where they are much lower). The activation energies correspponding to the parabolic process -and in some cases to the linear one- have been determined for each material. They are in the range 11 to 43 Kcal.mole -1 , such values being rather low. The characteristics of the oxide layers: mode and facies of nucleation and crystal growth -particularly of the ridges at grain boundaries- the evolution of interfaces, precipitation of magnetite within wustite, etc... have been thoroughly investigated. Finally mechanisms concerning the linear, transitory and parabolic oxidation processes have been proposed after a careful discussion of the results [fr

Photocatalytic Iron Oxide Micro-Swimmers for Environmental Remediation

Science.gov (United States)

Richard, Cynthia; Simmchen, Juliane; Eychmüller, Alexander

2018-05-01

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

A study on structural analysis of highly corrosive melts at high temperature

CERN Document Server

Ohtori, N

2002-01-01

When sodium is burned at high temperature in the atmosphere, it reacts simultaneously with H sub 2 O in the atmosphere so that it can produce high temperature melt of sodium hydroxide as a solvent. If this melt includes peroxide ion (O sub 2 sup 2 sup -), it will be a considerably active and corrosive for iron so that several sodium iron double oxides will be produced as corrosion products after the reaction with steel structures. The present study was carried out in order to investigate the ability of presence of peroxide ion in sodium hydroxide solvent at high temperature and that of identification of the several corrosion products using laser Raman spectroscopy. The measurement system with ultraviolet laser was developed simultaneously in the present work to improve the ability of the measurement at high temperature. As results from the measurements, the possibility of the presence of peroxide ion was shown up to 823K in sodium peroxide and 823K in the melt of sodium hydroxide mixed with sodium peroxide. A...

Water oxidation catalysis with nonheme iron complexes under acidic and basic conditions: homogeneous or heterogeneous?

Science.gov (United States)

Hong, Dachao; Mandal, Sukanta; Yamada, Yusuke; Lee, Yong-Min; Nam, Wonwoo; Llobet, Antoni; Fukuzumi, Shunichi

2013-08-19

Thermal water oxidation by cerium(IV) ammonium nitrate (CAN) was catalyzed by nonheme iron complexes, such as Fe(BQEN)(OTf)2 (1) and Fe(BQCN)(OTf)2 (2) (BQEN = N,N'-dimethyl-N,N'-bis(8-quinolyl)ethane-1,2-diamine, BQCN = N,N'-dimethyl-N,N'-bis(8-quinolyl)cyclohexanediamine, OTf = CF3SO3(-)) in a nonbuffered aqueous solution; turnover numbers of 80 ± 10 and 20 ± 5 were obtained in the O2 evolution reaction by 1 and 2, respectively. The ligand dissociation of the iron complexes was observed under acidic conditions, and the dissociated ligands were oxidized by CAN to yield CO2. We also observed that 1 was converted to an iron(IV)-oxo complex during the water oxidation in competition with the ligand oxidation. In addition, oxygen exchange between the iron(IV)-oxo complex and H2(18)O was found to occur at a much faster rate than the oxygen evolution. These results indicate that the iron complexes act as the true homogeneous catalyst for water oxidation by CAN at low pHs. In contrast, light-driven water oxidation using [Ru(bpy)3](2+) (bpy = 2,2'-bipyridine) as a photosensitizer and S2O8(2-) as a sacrificial electron acceptor was catalyzed by iron hydroxide nanoparticles derived from the iron complexes under basic conditions as the result of the ligand dissociation. In a buffer solution (initial pH 9.0) formation of the iron hydroxide nanoparticles with a size of around 100 nm at the end of the reaction was monitored by dynamic light scattering (DLS) in situ and characterized by X-ray photoelectron spectra (XPS) and transmission electron microscope (TEM) measurements. We thus conclude that the water oxidation by CAN was catalyzed by short-lived homogeneous iron complexes under acidic conditions, whereas iron hydroxide nanoparticles derived from iron complexes act as a heterogeneous catalyst in the light-driven water oxidation reaction under basic conditions.

Solid-stabilized emulsion formation using stearoyl lactylate coated iron oxide nanoparticles

Science.gov (United States)

Vengsarkar, Pranav S.; Roberts, Christopher B.

2014-10-01

Iron oxide nanoparticles can exhibit highly tunable physicochemical properties that are extremely important in applications such as catalysis, biomedicine and environmental remediation. The small size of iron oxide nanoparticles can be used to stabilize oil-in-water Pickering emulsions due to their high energy of adsorption at the interface of oil droplets in water. The objective of this work is to investigate the effect of the primary particle characteristics and stabilizing agent chemistry on the stability of oil-in-water Pickering emulsions. Iron oxide nanoparticles were synthesized by the co-precipitation method using stoichiometric amounts of Fe2+ and Fe3+ salts. Sodium stearoyl lactylate (SSL), a Food and Drug Administration approved food additive, was used to functionalize the iron oxide nanoparticles. SSL is useful in the generation of fat-in-water emulsions due to its high hydrophilic-lipophilic balance and its bilayer-forming capacity. Generation of a monolayer or a bilayer coating on the nanoparticles was controlled through systematic changes in reagent concentrations. The coated particles were then characterized using various analytical techniques to determine their size, their crystal structure and surface functionalization. The capacity of these bilayer coated nanoparticles to stabilize oil-in-water emulsions under various salt concentrations and pH values was also systematically determined using various characterization techniques. This study successfully demonstrated the ability to synthesize iron oxide nanoparticles (20-40 nm) coated with SSL in order to generate stable Pickering emulsions that were pH-responsive and resistant to significant destabilization in a saline environment, thereby lending themselves to applications in advanced oil spill recovery and remediation.

Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation

Energy Technology Data Exchange (ETDEWEB)

Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui, E-mail: sgzhou@soil.gd.cn

2015-08-15

Highlights: • Paddy soil contaminated with benzoate incubated with hematite and magnetite. • Iron oxides addition enhanced methanogenic benzoate degradation by 25–53%. • The facilitated syntrophy might involve direct interspecies electron transfer. • Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved. - Abstract: Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89–94% of the electrons released from benzoate oxidation were recovered in CH{sub 4} production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.

Laboratory Investigation of Complex Conductivity and Magnetic Susceptibility on Natural Iron Oxide Coated Sand

Science.gov (United States)

Wang, C.; Slater, L. D.; Day-Lewis, F. D.; Briggs, M. A.

2017-12-01

Redox reactions occurring at the oxic/anoxic interface where groundwater discharges to surface water commonly result in iron oxide deposition that coats sediment grains. With relatively large total surface area, these iron oxide coated sediments serve as a sink for sorption of dissolved contaminants, although this sink may be temporary if redox conditions fluctuate with varied flow conditions. Characterization of the distribution of iron oxides in streambed sediments could provide valuable understanding of biogeochemical reactions and the ability of a natural system to sorb contaminants. Towards developing a field methodology, we conducted laboratory spectral induced polarization (SIP) and magnetic susceptibility (MS) measurements on natural iron oxide coated sand (Fe-sand) with grain sizes ranging from 0.3 to 2.0 mm in order to assess the sensitivity of these measurements to iron oxides in sediments. The Fe-sand was also sorted by sieving into various grain sizes to study the impact of grain size on the polarization mechanisms. The unsorted Fe-sand saturated with 0.01 S/m NaCl solution exhibited a distinct phase response ( > 4 mrad) in the frequency range from 0.001 to 100 Hz whereas regular silica sand was characterized by a phase response less than 1 mrad under the same conditions. The presence of iron oxide substantially increased MS (3.08×10-3 SI) over that of regular sand ( Laboratory results demonstrated that SIP and MS may be well suited to mapping the distribution of iron oxides in streambed sediments associated with anoxic groundwater discharge.

Iron oxidation in different types of groundwater of Western Siberia

Energy Technology Data Exchange (ETDEWEB)

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

2009-04-15

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

[Utilization of a transferred arc-plasma rotating furnace to melt and found oxide mixtures at around 2000 degrees C (presentation of the film VULCANO)].

Science.gov (United States)

Cognet, G; Laffont, G; Jegou, C; Pierre, J; Journeau, C; Sudreau, F; Roubaud, A

1999-03-01

Unless security measures are taken, a hypothetical accident resulting from the loss of the cooling circuit in a pressurized water nuclear reactor could cause the heart of the reactor to melt forming a bath, called the corium, mainly composed of uranium, zirconium and iron oxides as well as the structural steel. This type of situation would be similar to the Three Mile Island accident in 1979. In order to limit the consequences of such an accident, the Atomic Energy Commission has implemented a large study program [1] to improve our understanding of corium behavior and determine solutions to stabilize it and avoid its propagation outside the unit. The VULCANO installation was designed in order to perform the trials using real materials which are indispensable to study all the phenomena involved. A film on the VULCANO trials was presented at the Henri Moissan commemorative session organized by the French National Academy of Pharmacy. The rotating furnace used to melt and found the mixture simulating the corium is a direct descendant of the pioneer work by Henri Moissan. An electrical arc is directed at the center of the load to melt which is maintained against the walls by centrifugal force. After six high-temperature trials performed with compositions without uranium oxide, the first trial with real corium showed that the magma spread rather well, a result which is quite favorable for cooling.

The Effect of Pressure on Iron Speciation in Silicate Melts at a Fixed Oxygen Fugacity: The Possibility of a Redox Profile Through a Terrestrial Magma Ocean

Science.gov (United States)

Armstrong, K.; Frost, D. J.; McCammon, C. A.; Rubie, D. C.; Boffa Ballaran, T.

2017-12-01

As terrestrial planets accreted, mantle silicates equilibrated with core-forming metallic iron, which would have imposed a mantle oxygen fugacity below the iron-wüstite oxygen buffer. Throughout Earth's history, however, the oxygen fugacity of at least the accessible portions of the upper mantle has been 4-5 orders of magnitude higher. The process that caused the rapid increase in the redox state of the mantle soon after core formation is unclear. Here we test the possibility that pressure stabilises ferric iron in silicate melts, as has been observed in silicate minerals. A deep magma ocean, which would have likely existed towards the end of accretion, could then develop a gradient in oxygen fugacity for a fixed ferric-ferrous ratio as a result of pressure. We have equilibrated an andesitic melt with a Ru-RuO2 buffer in a multianvil press between 5 and 24 GPa. Further experiments were performed on the same melt in equilibrium with iron metal. The recovered melts were then analysed using Mössbauer spectroscopy to determine the ferric/ferrous ratio. The results show that for the Ru-RuO2 buffer at lower pressures, the ferric iron content decreases with pressure, due to a positive volume change of the reaction FeO + 1/4O2 = FeO1.5. Ferric iron content also appears to be sensitive to water content at lower pressures. However, above 15 GPa this trend apparently reverses and the ferric iron content increases with pressure. This reversal in pressure dependence would drive the oxygen fugacity of a deep magma ocean with a fixed ferric/ferrous ratio down with increasing depth. This would create a redox gradient, where the magma ocean could potentially be in equilibrium with metallic iron at its base but more oxidised in its shallower regions. Crystallisation of this magma ocean could render an upper mantle oxygen fugacity similar to that in the Earth's accessible mantle today.

Lymphocyte DNA damage and oxidative stress in patients with iron deficiency anemia.

Science.gov (United States)

Aslan, Mehmet; Horoz, Mehmet; Kocyigit, Abdurrahim; Ozgonül, Saadet; Celik, Hakim; Celik, Metin; Erel, Ozcan

2006-10-10

Oxidant stress has been shown to play an important role in the pathogenesis of iron deficiency anemia. The aim of this study was to investigate the association between lymphocyte DNA damage, total antioxidant capacity and the degree of anemia in patients with iron deficiency anemia. Twenty-two female with iron deficiency anemia and 22 healthy females were enrolled in the study. Peripheral DNA damage was assessed using alkaline comet assay and plasma total antioxidant capacity was determined using an automated measurement method. Lymphocyte DNA damage of patients with iron deficiency anemia was significantly higher than controls (ptotal antioxidant capacity was significantly lower (ptotal antioxidant capacity and hemoglobin levels (r=0.706, ptotal antioxidant capacity and hemoglobin levels were negatively correlated with DNA damage (r=-0.330, p<0.05 and r=-0.323, p<0.05, respectively). In conclusion, both oxidative stress and DNA damage are increased in IDA patients. Increased oxidative stress seems as an important factor that inducing DNA damage in those IDA patients. The relationships of oxidative stress and DNA damage with the severity of anemia suggest that both oxidative stress and DNA damage may, in part, have a role in the pathogenesis of IDA.

Microbial Iron Oxidation in the Arctic Tundra and Its Implications for Biogeochemical Cycling

Science.gov (United States)

Scott, Jarrod J.; Benes, Joshua; Bowden, William B.

2015-01-01

The role that neutrophilic iron-oxidizing bacteria play in the Arctic tundra is unknown. This study surveyed chemosynthetic iron-oxidizing communities at the North Slope of Alaska near Toolik Field Station (TFS) at Toolik Lake (lat 68.63, long −149.60). Microbial iron mats were common in submerged habitats with stationary or slowly flowing water, and their greatest areal extent is in coating plant stems and sediments in wet sedge meadows. Some Fe-oxidizing bacteria (FeOB) produce easily recognized sheath or stalk morphotypes that were present and dominant in all the mats we observed. The cool water temperatures (9 to 11°C) and reduced pH (5.0 to 6.6) at all sites kinetically favor microbial iron oxidation. A microbial survey of five sites based on 16S rRNA genes found a predominance of Proteobacteria, with Betaproteobacteria and members of the family Comamonadaceae being the most prevalent operational taxonomic units (OTUs). In relative abundance, clades of lithotrophic FeOB composed 5 to 10% of the communities. OTUs related to cyanobacteria and chloroplasts accounted for 3 to 25% of the communities. Oxygen profiles showed evidence for oxygenic photosynthesis at the surface of some mats, indicating the coexistence of photosynthetic and FeOB populations. The relative abundance of OTUs belonging to putative Fe-reducing bacteria (FeRB) averaged around 11% in the sampled iron mats. Mats incubated anaerobically with 10 mM acetate rapidly initiated Fe reduction, indicating that active iron cycling is likely. The prevalence of iron mats on the tundra might impact the carbon cycle through lithoautotrophic chemosynthesis, anaerobic respiration of organic carbon coupled to iron reduction, and the suppression of methanogenesis, and it potentially influences phosphorus dynamics through the adsorption of phosphorus to iron oxides. PMID:26386054

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

NARCIS (Netherlands)

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

2015-01-01

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

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

NARCIS (Netherlands)

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

2015-01-01

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

Development of the inductive ring susceptor technique for sustaining oxide melts

International Nuclear Information System (INIS)

Copus, E.R.

1983-09-01

A method for melting and sustaining large volumes of UO 2 has been developed at Sandia. This capability will greatly enhance reactor safety studies in the areas of ex-vessel interactions and degraded core retention by providing out-of-pile simulation for the decay heat process that is inherent to reactor core debris. The method, referred to as the Inductive Ring Susceptor Technique, melts UO 2 powder via inductively heated susceptor rings fashioned from highly conductive refractory metal. These rings are embedded in the non-conductive charge material. Placement of the rings is designed for optimum heat transfer and a controlled pool-type geometry. The technique has been demonstrated by a series of sustained oxide melt experiments

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

Science.gov (United States)

Kim, Sangwon; Ponka, Prem

2002-01-01

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

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

KAUST Repository

Pan, Yue

2010-03-16

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

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

Energy Technology Data Exchange (ETDEWEB)

Taylor, P

1995-08-01

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

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

International Nuclear Information System (INIS)

Taylor, P.

1995-08-01

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

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

Directory of Open Access Journals (Sweden)

Bryan M. Hunter

2018-04-01

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

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

African Journals Online (AJOL)

JTEkanem

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

Fossilization of Iron-Oxidizing Bacteria at Hydrothermal Vents: a Useful Biosignature on Mars?

Science.gov (United States)

Leveille, R. J.; Lui, S.

2009-05-01

Iron oxidizing bacteria are ubiquitous in marine and terrestrial environments on Earth, where they often display distinctive cell morphologies and are commonly encrusted by minerals, especially bacteriogenic iron oxides and silica. Putative microfossils of iron oxidizing bacteria have been found in jaspers as old as 490Ma and microbial iron oxidation may be an ancient metabolic pathway. In order to investigate the usefulness of mineralized iron oxidizing bacteria as a biosignature, we have examined mineral samples collected from relict hydrothermal systems along Explorer Ridge, NE Pacific Ocean. In addition, microaerophilic, neutrophilic iron oxidizing bacteria, isolated from Pacific hydrothermal vents, were grown in a Fe-enriched seawater medium at constant pH (6.5) and oxygen concentration (5 percent) in a controlled bioreactor system. Both natural samples and experimental products were examined with a combination of variable pressure scanning electron microscopy (SEM), field emission gun SEM, and in some cases by preparing samples with a focused ion beam (FIB) milling system. Natural seafloor samples display abundant filamentous forms often resembling, in both size and shape, the twisted stalks of Gallionella and the elongated filaments of Leptothrix. Generally, these filamentous features are 1-5 microns in diameter and up to several microns in length. Some samples consist entirely of low- density, porous masses of silica encrusted filamentous forms. Presumably, these masses were formed by a rapid precipitation by the influx of silica-rich fluids into a microbial mat dominated by bacteria with filamentous morphologies. The presence of rare, amorphous (unmineralized) filamentous matter rich in C and Fe suggests that these bacteria were iron oxidizers. There is no evidence that sulfur oxidizers were present. Filamentous features sectioned by FIB milling show internal material within semi-hollow tubular-like features. Silica encrustations also show pseudo

Au/iron oxide catalysts: temperature programmed reduction and X-ray diffraction characterization

International Nuclear Information System (INIS)

Neri, G.; Visco, A.M.; Galvagno, S.; Donato, A.; Panzalorto, M.

1999-01-01

Gold on iron oxides catalysts have been characterized by temperature programmed reduction (TPR) and X-ray diffraction spectroscopy (XRD). The influence of preparation method, gold loading and pretreatment conditions on the reducibility of iron oxides have been investigated. On the impregnated Au/iron oxide catalysts as well as on the support alone the partial reduction of Fe(III) oxy(hydroxides) to Fe 3 O 4 starts in the 550 and 700 K temperature range. On the coprecipitated samples, the temperature of formation of Fe 3 O 4 is strongly dependent on the presence of gold. The reduction temperature is lowered as the gold loading is increased. The reduction of Fe 3 O 4 to FeO occurs at about 900 K and is not dependent on the presence of gold and the preparation method. It is suggested that the effect of gold on the reducibility of the iron oxides is related to an increase of the structural defects and/or of the surface hydroxyl groups. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Integrity of 111In-radiolabeled superparamagnetic iron oxide nanoparticles in the mouse

International Nuclear Information System (INIS)

Wang, Haotian; Kumar, Rajiv; Nagesha, Dattatri; Duclos, Richard I.; Sridhar, Srinivas; Gatley, Samuel J.

2015-01-01

Introduction: Iron-oxide nanoparticles can act as contrast agents in magnetic resonance imaging (MRI), while radiolabeling the same platform with nuclear medicine isotopes allows imaging with positron emission tomography (PET) or single-photon emission computed tomography (SPECT), modalities that offer better quantification. For successful translation of these multifunctional imaging platforms to clinical use, it is imperative to evaluate the degree to which the association between radioactive label and iron oxide core remains intact in vivo. Methods: We prepared iron oxide nanoparticles stabilized by oleic acid and phospholipids which were further radiolabeled with 59 Fe, 14 C-oleic acid, and 111 In. Results: Mouse biodistributions showed 111 In preferentially localized in reticuloendothelial organs, liver, spleen and bone. However, there were greater levels of 59 Fe than 111 In in liver and spleen, but lower levels of 14 C. Conclusions: While there is some degree of dissociation between the 111 In labeled component of the nanoparticle and the iron oxide core, there is extensive dissociation of the oleic acid component

Role of nitric oxide in cellular iron metabolism.

Science.gov (United States)

Kim, Sangwon; Ponka, Prem

2003-03-01

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

Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

Energy Technology Data Exchange (ETDEWEB)

Henych, Jiří, E-mail: henych@iic.cas.cz [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Janoš, Pavel; Kuráň, Pavel; Štastný, Martin [Faculty of the Environment, J.E. Purkyně University, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

2015-07-30

Highlights: • Ti–Fe mixed oxides were synthesized via low-temperature one-pot method. • Mixed oxides were used for degradation of parathion methyl. • Pure reference oxide samples showed no degradation ability. • Mixed oxides reached 70% degree of conversion of parathion methyl. - Abstract: Titania-iron mixed oxides with various Ti:Fe ratio were prepared by homogeneous hydrolysis of aqueous solutions of titanium(IV) oxysulphate and iron(III) sulphate with urea as a precipitating agent. The synthesized samples were characterized by X-ray diffraction, Raman and infrared spectroscopy, scanning and transmission electron microscopy, XRF analysis, specific surface area (BET) and porosity determination (BJH). These oxides were used for degradation of organophosporus pesticide parathion methyl. The highest degradation efficiency approaching <70% was found for the samples with Ti:Fe ratio 0.25:1 and 1:0.25. Contrary, parathion methyl was not degraded on the surfaces of pure oxides. In general, the highest degradation rate exhibited samples consisted of the iron or titanium oxide containing a moderate amount of the admixture. However, distinct correlations between the degradation rate and the sorbent composition were not identified.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Bacterial Oxidation and Reduction of Iron in the Processes of Creation and Treatment of Acid Mining Waters

Directory of Open Access Journals (Sweden)

Daniel Kupka

2004-12-01

Full Text Available Acid mine drainages (AMDs arise at the weathering of sulphidic minerals. The occurrence of acidic streams is commonly associated with the human mining activities. Due to the disruption and excavation of sulphide deposits, the oxidation processes have initiated. Acidic products of sulphide oxidation accelerate the degradation of accompanying minerals. AMDs typically contain high concentrations of sulfuric acid and soluble metals and cause serious ecological problems due to the water pollution and the devastation of adjacent country. Microbial life in these extremely acidic environments may be considerably diverse. AMDs are abundant in bacteria capable to oxidize and/or to reduce iron. The rate of bacterial oxidation of ferrous iron released from pyrite surfaces is up to one million times faster than the chemical oxidation rate at low pH. Bacterial regeneration of ferric iron maintains the continuity of pyrite oxidation and the production of AMDs. Another group of microorganisms living in these environments are acidophilic ferric iron reducing bacteria. This group of microorganisms has been discovered only relatively recently. Acidophilic heterotrophic bacteria reduce ferric iron in either soluble or solid forms to ferrous iron. The reductive dissolution of ferric iron minerals brings about a mobilization of iron as well as associated heavy metals. The Bacterial oxidation and reduction of iron play an important role in the transformation of either crystalline or amorphous iron-containing minerals, including sulphides, oxides, hydroxysulfates, carbonates and silicates. This work discusses the role of acidophilic bacteria in the natural iron cycling and the genesis of acidic effluents. The possibilities of application of iron bacteria in the remediation of AMDs are also considered.

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

Directory of Open Access Journals (Sweden)

Homa Mohseni Kouchesfehani

2016-07-01

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

Iron oxide nanoparticles stabilized inside highly ordered ...

Indian Academy of Sciences (India)

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

Thermal and magnetic properties of iron oxide colloids: influence of surfactants

International Nuclear Information System (INIS)

I P Soares, Paula; Lochte, Frederik; Echeverria, Coro; M M Ferreira, Isabel; P M R Borges, João; C J Pereira, Laura; T Coutinho, Joana; M M Novo, Carlos

2015-01-01

Iron oxide nanoparticles (NPs) have been extensively studied in the last few decades for several biomedical applications such as magnetic resonance imaging, magnetic drug delivery and hyperthermia. Hyperthermia is a technique used for cancer treatment which consists in inducing a temperature of about 41–45 °C in cancerous cells through magnetic NPs and an external magnetic field. Chemical precipitation was used to produce iron oxide NPs 9 nm in size coated with oleic acid and trisodium citrate. The influence of both stabilizers on the heating ability and in vitro cytotoxicity of the produced iron oxide NPs was assessed. Physicochemical characterization of the samples confirmed that the used surfactants do not change the particles’ average size and that the presence of the surfactants has a strong effect on both the magnetic properties and the heating ability. The heating ability of Fe_3O_4 NPs shows a proportional increase with the increase of iron concentration, although when coated with trisodium citrate or oleic acid the heating ability decreases. Cytotoxicity assays demonstrated that both pristine and trisodium citrate Fe_3O_4 samples do not reduce cell viability. However, oleic acid Fe_3O_4 strongly reduces cell viability, more drastically in the SaOs-2 cell line. The produced iron oxide NPs are suitable for cancer hyperthermia treatment and the use of a surfactant brings great advantages concerning the dispersion of NPs, also allowing better control of the hyperthermia temperature. (paper)

Comparative study of crystallized melt-spun iron-boron alloys by Moessbauer effect and resistivity measurements

International Nuclear Information System (INIS)

Arshad, M.; Siddique, M.; Anwar-ul-Islam, M.; Butt, N.M.; Ashfaq, A.; Shamim, A.

1993-01-01

Moessbauer study of two as-quenched, melt-spun iron-boron completely crystallized alloys, Fe/sub 72/01/B/sub 28/ and Fe/sub 88/01/B/sub 12/, indicates the presence of alpha-Fe, Fe/sub 2/B and Fe/sub 3/B. The percentage of these phases is different in the two alloys. Resistivity measurements show to phase transformation of Fe/sub 3/B and Fe/sub 2/B, respectively. (author)

Mercury removal in wastewater by iron oxide nanoparticles

International Nuclear Information System (INIS)

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

2016-01-01

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

Suppression of cavitation in melted tungsten by doping with lanthanum oxide

International Nuclear Information System (INIS)

Yuan, Y.; Lu, G.H.; Xu, B.; Fu, B.Q.; Xu, H.Y.; Li, C.; Jia, Y.Z.; Qu, S.L.; Liu, W.; Greuner, H.; Böswirth, B.; Luo, G.-N.

2014-01-01

Melting and boiling behaviour of pure tungsten and 1 wt% lanthanum-oxide-doped tungsten (WL10) are investigated, focusing on the material selection with respect to material loss induced by cavitation. Melting experiments under high heat loads are carried out in the high heat flux facility GLADIS. Pulsed hydrogen neutral beams with heat flux of 10 and 23 MW m −2 are applied onto the adiabatically loaded samples for intense surface melting. Melt layer of the two tungsten grades exhibit different microstructure characteristics. Substantive voids owing to cavitation in the liquid phase are observed in pure W and lead to porous resolidified material. However, little cavitation bubbles can be found in the dense resolidified layer of WL10. In order to find out the gaseous sources, vapour collection is performed and the components are subsequently detected. Based on the observations and analyses, the microstructure evolutions corresponding to melting and vapourization behaviour of the two tungsten grades are tentatively described, and furthermore, the underlying mechanisms of cavitation in pure W and its suppression in WL10 are discussed. (paper)

Method of melting decontamination of radioactive contaminated metals

International Nuclear Information System (INIS)

Uda, Tatsuhiko; Miura, Noboru; Tsuchiya, Hiroyuki.

1984-01-01

Purpose: To improve the transfer efficiency of radioactive materials into slags. Method: Contaminated metals are melt with adding slagging agent in order to transfer the radioactive materials into the slag, where the slagging agent holds less free energy than that of metal oxides contaminated with radioactive materials in order to promote the transfer of the contaminated materials into the slag layer. This effect can also be attained on metals or alloys other than iron contaminated with radioactive materials. In the case of alloy, the slagging agent is to containing such metal oxide that free energy is less than that of the oxide of metal being the main ingredient element of the alloy. The decontamination effect can further be improved by containing halogenide such as calcium fluoride together with the metal oxide into the slagging agent. (Ikeda, J.)

Scalable high-affinity stabilization of magnetic iron oxide nanostructures by a biocompatible antifouling homopolymer

KAUST Repository

Luongo, Giovanni; Campagnolo, Paola; Perez, Jose E.; Kosel, Jü rgen; Georgiou, Theoni K.; Regoutz, Anna; Payne, David J; Stevens, Molly M.; Ryan, Mary P.; Porter, Alexandra E; Dunlop, Iain E

2017-01-01

Iron oxide nanostructures have been widely developed for biomedical applications, due to their magnetic properties and biocompatibility. In clinical application, the stabilization of these nanostructures against aggregation and non-specific interactions is typically achieved using weakly anchored polysaccharides, with better-defined and more strongly anchored synthetic polymers not commercially adopted due to complexity of synthesis and use. Here, we show for the first time stabilization and biocompatibilization of iron oxide nanoparticles by a synthetic homopolymer with strong surface anchoring and a history of clinical use in other applications, poly(2-methacryloyloxyethy phosphorylcholine) (poly(MPC)). For the commercially important case of spherical particles, binding of poly(MPC) to iron oxide surfaces and highly effective individualization of magnetite nanoparticles (20 nm) are demonstrated. Next-generation high-aspect ratio nanowires (both magnetite/maghemite and core-shell iron/iron oxide) are furthermore stabilized by poly(MPC)-coating, with nanowire cytotoxicity at large concentrations significantly reduced. The synthesis approach is exploited to incorporate functionality into the poly(MPC) chain is demonstrated by random copolymerization with an alkyne-containing monomer for click-chemistry. Taking these results together, poly(MPC) homopolymers and random copolymers offer a significant improvement over current iron oxide nanoformulations, combining straightforward synthesis, strong surface-anchoring and well-defined molecular weight.

Scalable high-affinity stabilization of magnetic iron oxide nanostructures by a biocompatible antifouling homopolymer

KAUST Repository

Luongo, Giovanni

2017-10-12

Iron oxide nanostructures have been widely developed for biomedical applications, due to their magnetic properties and biocompatibility. In clinical application, the stabilization of these nanostructures against aggregation and non-specific interactions is typically achieved using weakly anchored polysaccharides, with better-defined and more strongly anchored synthetic polymers not commercially adopted due to complexity of synthesis and use. Here, we show for the first time stabilization and biocompatibilization of iron oxide nanoparticles by a synthetic homopolymer with strong surface anchoring and a history of clinical use in other applications, poly(2-methacryloyloxyethy phosphorylcholine) (poly(MPC)). For the commercially important case of spherical particles, binding of poly(MPC) to iron oxide surfaces and highly effective individualization of magnetite nanoparticles (20 nm) are demonstrated. Next-generation high-aspect ratio nanowires (both magnetite/maghemite and core-shell iron/iron oxide) are furthermore stabilized by poly(MPC)-coating, with nanowire cytotoxicity at large concentrations significantly reduced. The synthesis approach is exploited to incorporate functionality into the poly(MPC) chain is demonstrated by random copolymerization with an alkyne-containing monomer for click-chemistry. Taking these results together, poly(MPC) homopolymers and random copolymers offer a significant improvement over current iron oxide nanoformulations, combining straightforward synthesis, strong surface-anchoring and well-defined molecular weight.

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

Czech Academy of Sciences Publication Activity Database

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

2016-01-01

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

Enhancement of aspirin capsulation by porous particles including iron hydrous oxide

International Nuclear Information System (INIS)

Saito, Kenji; Koishi, Masumi; Hosoi, Fumio; Makuuchi, Keizo.

1986-01-01

Polymer-coated porous particles containing aspirin as a drug were prepared and the release of rate of aspirin was studied. The impregnation of aspirin was carried out by post-graft polymerization, where methyl methacrylate containing aspirin was treated with porous particles including iron oxide, pre-irradiated with γ-ray form Co-60. Release of aspirin from modified particles was examined with 50 % methanol solution. The amount of aspirin absorbed in porous particles increased by grafting of methyl methacrylate. The particles treated with iron hydrous oxide sols before irradiation led to the increment of aspirin absorption. Diffusion of aspirin through the polymer matrix and the gelled layer was the limiting process in the aspirin release from particles. The rate of aspirin released from modified particles including iron hydrous oxide wasn't affected by the grafting of methyl methacrylate. (author)

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

International Nuclear Information System (INIS)

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

2006-01-01

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

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

Directory of Open Access Journals (Sweden)

Mfon Udo

2018-05-01

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

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

CSIR Research Space (South Africa)

Maree

1998-01-01

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

Solubility of rare earth-iron borates in the Bi2O3-B2O3 melt and their crystallization

International Nuclear Information System (INIS)

Al'shinskaya, L.I.; Leonyuk, N.I.; Nadezhnaya, T.B.; Timchenko, T.I.

1979-01-01

The temperature dependence of solubility of RFe 3 (BO 3 ) 4 (R=Y, Gd, Nd, Er) double borates in the Bi 2 O 3 -B 2 O 3 solution-melt is studied. The solubility curves in the range from 25 to 52 mol% are plotted. The character of curves is almost similar. At equal temperatures YFe 3 (BO 3 ) 4 and ErFe 3 (BO 3 ) 4 have the highest solubility and GaFe 3 (BO 3 ) 4 - the lowest one. It is shown that in the Bi 2 O 3 -B 2 O 3 base solution-melt the wide temperature range of monophase crystallization of rare earth - iron borates exists and the stratification is not observed. Thus, for the first time obtained are the crystals of rare earth-iron borates suitable for the investigation of their physical properties

Intraplate mantle oxidation by volatile-rich silicic magmas

Energy Technology Data Exchange (ETDEWEB)

Martin, Audrey M.; Médard, Etienne; Righter, Kevin; Lanzirotti, Antonio

2017-11-01

The upper subcontinental lithospheric mantle below the French Massif Central is more oxidized than the average continental lithosphere, although the origin of this anomaly remains unknown. Using iron oxidation analysis in clinopyroxene, oxybarometry, and melt inclusions in mantle xenoliths, we show that widespread infiltration of volatile (HCSO)-rich silicic melts played a major role in this oxidation. We propose the first comprehensive model of magmatism and mantle oxidation at an intraplate setting. Two oxidizing events occurred: (1) a 365–286 Ma old magmatic episode that produced alkaline vaugnerites, potassic lamprophyres, and K-rich calc-alkaline granitoids, related to the N–S Rhenohercynian subduction, and (2) < 30 Ma old magmatism related to W–E extension, producing carbonatites and hydrous potassic trachytes. These melts were capable of locally increasing the subcontinental lithospheric mantle fO2 to FMQ + 2.4. Both events originate from the melting of a metasomatized lithosphere containing carbonate + phlogopite ± amphibole. The persistence of this volatile-rich lithospheric source implies the potential for new episodes of volatile-rich magmatism. Similarities with worldwide magmatism also show that the importance of volatiles and the oxidation of the mantle in intraplate regions is underestimated.

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

International Nuclear Information System (INIS)

Hobert, H.; Arnold, D.

1975-01-01

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

Iron oxide nanoparticles for use in contrast agents in magnetic resonance imaging

International Nuclear Information System (INIS)

Oliveira, Elisa M.N. de; Rocha, Maximiliano S. da; Caimi, Priscila de A.; Basso, Nara R. de S.; Zanini, Mara L.; Papaleo, Ricardo M.

2015-01-01

In this work were carried out synthesis of iron oxide nanoparticles coated with dextran, comparing the results of using different concentrations of dextran, iron salts, temperature and reaction time. The compounds were analyzed by DLS, XRD, TGA, TEM, FTIR, Zeta Potential and relaxivity. Nanoparticles with dispersion around 10-15 nm and average hydrodynamic diameters of 16-50 nm, with superparamagnetic behavior were obtained. The ratio of the relaxivities (r2/r1) in aqueous solutions was 5.30, close to value of the commercially available iron oxide contrast agents. (author)

Nitric oxide and plant iron homeostasis.

Science.gov (United States)

Buet, Agustina; Simontacchi, Marcela

2015-03-01

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

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

KAUST Repository

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

2010-01-01

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

Elucidation of the electrochromic mechanism of nanostructured iron oxides films

Energy Technology Data Exchange (ETDEWEB)

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

2011-02-15

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

Scalable fractionation of iron oxide nanoparticles using a CO2 gas-expanded liquid system

International Nuclear Information System (INIS)

Vengsarkar, Pranav S.; Xu, Rui; Roberts, Christopher B.

2015-01-01

Iron oxide nanoparticles exhibit highly size-dependent physicochemical properties that are important in applications such as catalysis and environmental remediation. In order for these size-dependent properties to be effectively harnessed for industrial applications scalable and cost-effective techniques for size-controlled synthesis or size separation must be developed. The synthesis of monodisperse iron oxide nanoparticles can be a prohibitively expensive process on a large scale. An alternative involves the use of inexpensive synthesis procedures followed by a size-selective processing technique. While there are many techniques available to fractionate nanoparticles, many of the techniques are unable to efficiently fractionate iron oxide nanoparticles in a scalable and inexpensive manner. A scalable apparatus capable of fractionating large quantities of iron oxide nanoparticles into distinct fractions of different sizes and size distributions has been developed. Polydisperse iron oxide nanoparticles (2–20 nm) coated with oleic acid used in this study were synthesized using a simple and inexpensive version of the popular coprecipitation technique. This apparatus uses hexane as a CO 2 gas-expanded liquid to controllably precipitate nanoparticles inside a 1L high-pressure reactor. This paper demonstrates the operation of this new apparatus and for the first time shows the successful fractionation results on a system of metal oxide nanoparticles, with initial nanoparticle concentrations in the gram-scale. The analysis of the obtained fractions was performed using transmission electron microscopy and dynamic light scattering. The use of this simple apparatus provides a pathway to separate large quantities of iron oxide nanoparticles based upon their size for use in various industrial applications.

A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

International Nuclear Information System (INIS)

Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang

2016-01-01

Highlights: • A general melt-injection-decomposition (MID) route is proposed for the fabrication of oriented metal oxide nanowire arrays. • Four kinds of metal oxide (CuO, Mn_2O_3, Co_3O_4 and Cr_2O_3) nanowire arrays have been realized as examples through the developed MID route. • The mechanism of the developed MID route is discussed using Thermogravimetry and Differential Thermal Analysis technique. • The MID route is a versatile, simple, facile and effective way to prepare different kinds of oriented metal oxide nanowire arrays in the future. - Abstract: In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn_2O_3, Co_3O_4 and Cr_2O_3) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

Effect of calcium oxide on the efficiency of ferrous ion oxidation and total iron precipitation during ferrous ion oxidation in simulated acid mine drainage treatment with inoculation of Acidithiobacillus ferrooxidans.

Science.gov (United States)

Liu, Fenwu; Zhou, Jun; Jin, Tongjun; Zhang, Shasha; Liu, Lanlan

2016-01-01

Calcium oxide was added into ferrous ion oxidation system in the presence of Acidithiobacillus ferrooxidans at concentrations of 0-4.00 g/L. The pH, ferrous ion oxidation efficiency, total iron precipitation efficiency, and phase of the solid minerals harvested from different treatments were investigated during the ferrous ion oxidation process. In control check (CK) system, pH of the solution decreased from 2.81 to 2.25 when ferrous ions achieved complete oxidation after 72 h of Acidithiobacillus ferrooxidans incubation without the addition of calcium oxide, and total iron precipitation efficiency reached 20.2%. Efficiency of ferrous ion oxidation and total iron precipitation was significantly improved when the amount of calcium oxide added was ≤1.33 g/L, and the minerals harvested from systems were mainly a mixture of jarosite and schwertmannite. For example, the ferrous ion oxidation efficiency reached 100% at 60 h and total iron precipitation efficiency was increased to 32.1% at 72 h when 1.33 g/L of calcium oxide was added. However, ferrous ion oxidation and total iron precipitation for jarosite and schwertmannite formation were inhibited if the amount of calcium oxide added was above 2.67 g/L, and large amounts of calcium sulfate dihydrate were generated in systems.

Characterization of ash melting behaviour at high temperatures under conditions simulating combustible solid waste gasification.

Science.gov (United States)

Niu, Miaomiao; Dong, Qing; Huang, Yaji; Jin, Baosheng; Wang, Hongyan; Gu, Haiming

2018-05-01

To achieve high-temperature gasification-melting of combustible solid waste, ash melting behaviour under conditions simulating high-temperature gasification were studied. Raw ash (RA) and gasified ash (GA) were prepared respectively by waste ashing and fluidized bed gasification. Results of microstructure and composition of the two-ash indicated that GA showed a more porous structure and higher content of alkali and alkali earth metals among metallic elements. Higher temperature promoted GA melting and could reach a complete flowing state at about 1250°C. The order of melting rate of GA under different atmospheres was reducing condition > inert condition > oxidizing condition, which might be related to different existing forms of iron during melting and different flux content with atmosphere. Compared to RA, GA showed lower melting activity at the same condition due to the existence of an unconverted carbon and hollow structure. The melting temperature for sufficient melting and separation of GA should be at least 1250°C in this work.

Recovery of iron oxides from acid mine drainage and their application as adsorbent or catalyst.

Science.gov (United States)

Flores, Rubia Gomes; Andersen, Silvia Layara Floriani; Maia, Leonardo Kenji Komay; José, Humberto Jorge; Moreira, Regina de Fatima Peralta Muniz

2012-11-30

Iron oxide particles recovered from acid mine drainage represent a potential low-cost feedstock to replace reagent-grade chemicals in the production of goethite, ferrihydrite or magnetite with relatively high purity. Also, the properties of iron oxides recovered from acid mine drainage mean that they can be exploited as catalysts and/or adsorbents to remove azo dyes from aqueous solutions. The main aim of this study was to recover iron oxides with relatively high purity from acid mine drainage to act as a catalyst in the oxidation of dye through a Fenton-like mechanism or as an adsorbent to remove dyes from an aqueous solution. Iron oxides (goethite) were recovered from acid mine drainage through a sequential precipitation method. Thermal treatment at temperatures higher than 300 °C produces hematite through a decrease in the BET area and an increase in the point of zero charge. In the absence of hydrogen peroxide, the solids adsorbed the textile dye Procion Red H-E7B according to the Langmuir model, and the maximum amount adsorbed decreased as the temperature of the thermal treatment increased. The decomposition kinetics of hydrogen peroxide is dependent on the H(2)O(2) concentration and iron oxides dosage, but the second-order rate constant normalized to the BET surface area is similar to that for different iron oxides tested in this and others studies. These results indicate that acid mine drainage could be used as a source material for the production of iron oxide catalysts/adsorbents, with comparable quality to those produced using analytical-grade reagents. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of surface oxide on the melting behavior of lead-free solder nanowires and nanorods

International Nuclear Information System (INIS)

Gao Fan; Rajathurai, Karunaharan; Cui, Qingzhou; Zhou, Guangwen; NkengforAcha, Irene; Gu Zhiyong

2012-01-01

Lead-free nanosolders have shown promise in nanowire and nanoelectronics assembly. Among various important parameters, melting is the most fundamental property affecting the assembly process. Here we report that the melting behavior of tin and tin/silver nanowires and nanorods can be significantly affected by the surface oxide of nanosolders. By controlling the nanosolder reflow atmosphere using a flux, the surface oxide of the nanowires/nanorods can be effectively removed and complete nanosolder melting can be achieved. The complete melting of the nanosolders leads to the formation of nanoscale to microscale spherical solder balls, followed by Ostwald ripening phenomenon. The contact angle of the microscale solder balls formed on Si substrate was measured by direct electron microscopic imaging. These results provide new insights into micro- and nanoscale phase transition and liquid droplet coalescence from nanowires/nanorods to spheroids, and are relevant to nanoscale assembly and smaller ball grid array formation.

Immunological effects of iron oxide nanoparticles and iron-based complex drug formulations: Therapeutic benefits, toxicity, mechanistic insights, and translational considerations.

Science.gov (United States)

Shah, Ankit; Dobrovolskaia, Marina A

2018-04-01

Nanotechnology offers several advantages for drug delivery. However, there is the need for addressing potential safety concerns regarding the adverse health effects of these unique materials. Some such effects may occur due to undesirable interactions between nanoparticles and the immune system, and they may include hypersensitivity reactions, immunosuppression, and immunostimulation. While strategies, models, and approaches for studying the immunological safety of various engineered nanoparticles, including metal oxides, have been covered in the current literature, little attention has been given to the interactions between iron oxide-based nanomaterials and various components of the immune system. Here we provide a comprehensive review of studies investigating the effects of iron oxides and iron-based nanoparticles on various types of immune cells, highlight current gaps in the understanding of the structure-activity relationships of these materials, and propose a framework for capturing their immunotoxicity to streamline comparative studies between various types of iron-based formulations. Copyright © 2018 Elsevier Inc. All rights reserved.

Synthesis, Characterization, and Cytotoxicity of Iron Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

S. Kanagesan

2013-01-01

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

Novel magnetically separable AgCl/iron oxide composites with enhanced photocatalytic activity driven by visible light

International Nuclear Information System (INIS)

Zhang, Ying; Zhang, Yanrong; Tan, Jue

2013-01-01

Highlights: •The AgCl/iron oxide composites were prepared by a chemical precipitation method. •The composites exhibited improved performances in the photodegradation of pollutants. •The visible light photocatalysts could be recycled easily by a magnet. -- Abstract: In this work, AgCl/iron oxide composites were synthesized by a simple chemical precipitation method and calcining process. The composition of the material and magnetic and optical properties of the composites were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating specimen magnetometer (VSM) techniques, which confirms the high crystalline and magnetic behavior of the composites. UV-vis diffuse reflectance spectral (DRS) studies showed that the AgCl/iron oxide composites were of much higher absorption in longer wavelength region compared to bare iron oxide. The AgCl/iron oxide composites showed better performance in the photodegradation of organic dyes Rhodamin B (RhB) under the fluorescent lamp irradiation, which is remarkably superior to the N-TiO 2 . The degradation of microcystin-LR (MC-LR) and phenol was also found to be good owing to its effective electron-hole separation at AgCl/iron oxide interface. The separation of AgCl/iron oxide composites from the treated water was achieved by an external magnetic field as γ-Fe 2 O 3 exhibits enough magnetic power to facilitate the separation

DNA-length-dependent quenching of fluorescently labeled iron oxide nanoparticles with gold, graphene oxide and MoS2 nanostructures.

Science.gov (United States)

Balcioglu, Mustafa; Rana, Muhit; Robertson, Neil; Yigit, Mehmet V

2014-08-13

We controlled the fluorescence emission of a fluorescently labeled iron oxide nanoparticle using three different nanomaterials with ultraefficient quenching capabilities. The control over the fluorescence emission was investigated via spacing introduced by the surface-functionalized single-stranded DNA molecules. DNA molecules were conjugated on different templates, either on the surface of the fluorescently labeled iron oxide nanoparticles or gold and nanographene oxide. The efficiency of the quenching was determined and compared with various fluorescently labeled iron oxide nanoparticle and nanoquencher combinations using DNA molecules with three different lengths. We have found that the template for DNA conjugation plays significant role on quenching the fluorescence emission of the fluorescently labeled iron oxide nanoparticles. We have observed that the size of the DNA controls the quenching efficiency when conjugated only on the fluorescently labeled iron oxide nanoparticles by setting a spacer between the surfaces and resulting change in the hydrodynamic size. The quenching efficiency with 12mer, 23mer and 36mer oligonucleotides decreased to 56%, 54% and 53% with gold nanoparticles, 58%, 38% and 32% with nanographene oxide, 46%, 38% and 35% with MoS2, respectively. On the other hand, the presence, not the size, of the DNA molecules on the other surfaces quenched the fluorescence significantly with different degrees. To understand the effect of the mobility of the DNA molecules on the nanoparticle surface, DNA molecules were attached to the surface with two different approaches. Covalently immobilized oligonucleotides decreased the quenching efficiency of nanographene oxide and gold nanoparticles to ∼22% and ∼21%, respectively, whereas noncovalently adsorbed oligonucleotides decreased it to ∼25% and ∼55%, respectively. As a result, we have found that each nanoquencher has a powerful quenching capability against a fluorescent nanoparticle, which can be

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

Science.gov (United States)

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

2016-11-01

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

'NC100150', a preparation of iron oxide nanoparticles ideal for positive-contrast MR angiography.

Science.gov (United States)

Kellar, K E; Fujii, D K; Gunther, W H; Briley-Saebø, K; Spiller, M; Koenig, S H

1999-08-01

A laboratory-scale synthesis of NC100150 (iron oxide particles with an oxidized starch coating) was characterized by magnetization measurements (vibrating sample magnetometry, VSM), relaxometry (1/T1 NMRD profiles and 1/T2 at 10 and 20 MHz), and dynamic light scattering (photon correlation spectroscopy, PCS). The results were related to give a self-consistent physical description of the particles: a water-impenetrable part making up 12% of the total particle volume, 82% of this volume consisting of an iron oxide core and the remaining 18% consisting of an oxidized starch rind; and, a water-penetrable part making up 88% of the total particle volume, consisting of oxidized starch polymers and entrained water molecules. Relating the magnetization to the relaxometry results required that the oxidized starch coating slows the diffusivity of solvent water molecules in the vicinity of the iron oxide cores. The effect of the organic coating on water diffusivity, not previously considered in the application of relaxation theory to iron oxide nanoparticles, is supported by the much greater (factor of about 2) diameter obtained from the dynamic light scattering measurements in comparison to that obtained from the magnetization measurements. The present work shows that three physical techniques--VSM, relaxometry, and PCS--are needed for properly assessing iron oxide nanoparticles for use as contrast agents for magnetic resonance angiography (MRA). It is also shown that NC100150 has a narrow range of diameters and the smallest value of r2/r1 reported to date, an asset for MRA.

Heterogeneous biomimetic catalysis using iron porphyrin for cyclohexane oxidation promoted by chitosan

Science.gov (United States)

Huang, Guan; Liu, Yao; Cai, Jing Li; Chen, Xiang Feng; Zhao, Shu Kai; Guo, Yong An; Wei, Su Juan; Li, Xu

2017-04-01

This study investigates how ligands modulate metalloporphyrin activity with the goal of producing a practical biomimetic catalyst for use in the chemical industry. We immobilized iron porphyrinate [iron-tetrakis-(4-sulfonatophenyl)-porphyrin; Fe(III) (TPPS)] on powdered chitosan (pd-CTS) to form an immobilized catalyst Fe(III) (TPPS)/pd-CTS, which was characterized using modern spectroscopic techniques and used for catalytic oxidation of cyclohexane with O2. Amino coordination to iron porphyrin in Fe(III) (TPPS)/pd-CTS altered the electron cloud density around the iron cation, probably by reducing the activation energy of Fe(III) (TPPS) and raising the reactivity of the iron ion catalytic center, thereby improving the catalytic efficiency. One milligram of Fe(III) (TPPS) catalyst can be reused three times for the oxidation reaction to yield an average of 22.9 mol% of cyclohexanone and cyclohexanol.

Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI) Role

KAUST Repository

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

2017-01-01

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

Multiferroic iron oxide thin films at room temperature

Czech Academy of Sciences Publication Activity Database

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

2014-01-01

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

Reaction modelling of Iron Oxide Bromination in the UT-3 thermochemical cycle for Hydrogen production from water

International Nuclear Information System (INIS)

Amir-Rusli

1996-01-01

Analysis modelling of the iron oxide bromination had been carried out using experiment data from the iron oxide bromination in the UT-3 thermochemical cycle. Iron oxide in the form of pellets were made of the calcination of the mixture of iron oxide, silica, graphite and cellulose at 1473 K. Thermobalance reactor was used to study the kinetic reactions of the iron oxide bromination at a temperature of 473 K for 2 - 6 hours. The data collected from the experiments were used as input for the common models. However, none of these models could not explain the result of the experiments. A new model, a combination of two kinetic reactions : exposed particle and coated particle was created and worked successfully

Methods of preparing deposits containing iron oxides for recycling

Directory of Open Access Journals (Sweden)

T. Lis

2013-04-01

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

Iron-Mediated Oxidation of Methoxyhydroquinone under Dark Conditions: Kinetic and Mechanistic Insights.

Science.gov (United States)

Yuan, Xiu; Davis, James A; Nico, Peter S

2016-02-16

Despite the biogeochemical significance of the interactions between natural organic matter (NOM) and iron species, considerable uncertainty still remains as to the exact processes contributing to the rates and extents of complexation and redox reactions between these important and complex environmental components. Investigations on the reactivity of low-molecular-weight quinones, which are believed to be key redox active compounds within NOM, toward iron species, could provide considerable insight into the kinetics and mechanisms of reactions involving NOM and iron. In this study, the oxidation of 2-methoxyhydroquinone (MH2Q) by ferric iron (Fe(III)) under dark conditions in the absence and presence of oxygen was investigated within a pH range of 4-6. Although Fe(III) was capable of stoichiometrically oxidizing MH2Q under anaerobic conditions, catalytic oxidation of MH2Q was observed in the presence of O2 due to further cycling between oxygen, semiquinone radicals, and iron species. A detailed kinetic model was developed to describe the predominant mechanisms, which indicated that both the undissociated and monodissociated anions of MH2Q were kinetically active species toward Fe(III) reduction, with the monodissociated anion being the key species accounting for the pH dependence of the oxidation. The generated radical intermediates, namely semiquinone and superoxide, are of great importance in reaction-chain propagation. The kinetic model may provide critical insight into the underlying mechanisms of the thermodynamic and kinetic characteristics of metal-organic interactions and assist in understanding and predicting the factors controlling iron and organic matter transformation and bioavailability in aquatic systems.

Biogeochemistry of pyrite and iron sulfide oxidation in marine sediments

DEFF Research Database (Denmark)

Schippers, A.; Jørgensen, BB

2002-01-01

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

N-butylamine functionalized graphene oxide for detection of iron(III) by photoluminescence quenching.

Science.gov (United States)

Gholami, Javad; Manteghian, Mehrdad; Badiei, Alireza; Ueda, Hiroshi; Javanbakht, Mehran

2016-02-01

An N-butylamine functionalized graphene oxide nanolayer was synthesized and characterized by ultraviolet (UV)-visible spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Detection of iron(III) based on photoluminescence spectroscopy was investigated. The N-butylamine functionalized graphene oxide was shown to specifically interact with iron (III), compared with other cationic trace elements including potassium (I), sodium (I), calcium (II), chromium (III), zinc (II), cobalt (II), copper (II), magnesium (II), manganese (II), and molybdenum (VI). The quenching effect of iron (III) on the luminescence emission of N-butylamine functionalized graphene oxide layer was used to detect iron (III). The limit of detection (2.8 × 10(-6)  M) and limit of quantitation (2.9 × 10(-5)  M) were obtained under optimal conditions. Copyright © 2015 John Wiley & Sons, Ltd.

Towards a Mechanistic Understanding of Anaerobic Nitrate Dependent Iron Oxidation: Balancing Electron Uptake and Detoxification

Directory of Open Access Journals (Sweden)

Hans Karl Carlson

2012-02-01

Full Text Available The anaerobic oxidation of Fe(II by subsurface microorganisms is an important part of biogeochemical cycling in the environment, but the biochemical mechanisms used to couple iron oxidation to nitrate respiration are not well understood. Based on our own work and the evidence available in the literature, we propose a mechanistic model for anaerobic nitrate dependent iron oxidation. We suggest that anaerobic iron oxidizing microorganisms likely exist along a continuum including: 1 bacteria that inadvertently oxidize Fe(II by abiotic or biotic reactions with enzymes or chemical intermediates in their metabolic pathways (e.g. denitrification and suffer from toxicity or energetic penalty, 2 Fe(II tolerant bacteria that gain little or no growth benefit from iron oxidation but can manage the toxic reactions, and 3 bacteria that efficiently accept electrons from Fe(II to gain a growth advantage while preventing or mitigating the toxic reactions. Predictions of the proposed model are highlighted and experimental approaches are discussed.

Integrated System of Thermal/Dimensional Analysis for Quality Control of Metallic Melt and Ductile Iron Casting Solidification

Science.gov (United States)

Stan, Stelian; Chisamera, Mihai; Riposan, Iulian; Neacsu, Loredana; Cojocaru, Ana Maria; Stan, Iuliana

2018-03-01

The main objective of the present work is to introduce a specific experimental instrument and technique for simultaneously evaluating cooling curves and expansion or contraction of cast metals during solidification. Contraction/expansion analysis illustrates the solidification parameters progression, according to the molten cast iron characteristics, which are dependent on the melting procedure and applied metallurgical treatments, mold media rigidity and thermal behavior [heat transfer parameters]. The first part of the paper summarizes the performance of this two-mold device. Its function is illustrated by representative shrinkage tendency results in ductile cast iron as affected by mold rigidity (green sand and furan resin sand molds) and inoculant type (FeSi-based alloys), published in part previously. The second part of the paper illustrates an application of this equipment adapted for commercial foundry use. It conducts thermal analysis and volume change measurements in a single ceramic cup so that mold media as well as solidification conditions are constants, with cast iron quality as the variable. Experiments compared gray and ductile cast iron solidification patterns. Gray iron castings are characterized by higher undercooling at the beginning and at the end of solidification and lower graphitic expansion. Typically, ductile cast iron exhibits higher graphitic, initial expansion, conducive for shrinkage formation in soft molds.

Promising iron oxide-based magnetic nanoparticles in biomedical engineering.

Science.gov (United States)

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

2012-12-01

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

Mechanism of iron catalyzed oxidation of SO/sub 2/ in oxygenated solutions

Energy Technology Data Exchange (ETDEWEB)

Freiberg, J

1975-01-01

Previous experimental work concerning the iron catalyzed oxidation of SO/sub 2/ in oxygenated acid solutions failed to provide a consistent reaction mechanism and rate expression. As iron is one of the main constituents of urban atmospheric aerosols, the rate studies of heterogeneous sulphate formation in polluted city air were hampered. The present study develops a new theory for the iron catalyzed oxidation of SO/sub 2/. The resulting new rate expression is general enough to account for the results of previous experimental investigations that were performed in different ranges of SO/sub 2/ and catalyst concentrations.

Iron and stony-iron meteorites

DEFF Research Database (Denmark)

Ruzicka, Alex M.; Haack, Henning; Chabot, Nancy L.

2017-01-01

By far most of the melted and differentiated planetesimals that have been sampled as meteorites are metal-rich iron meteorites or stony iron meteorites. The parent asteroids of these meteorites accreted early and differentiated shortly after the solar system formed, producing some of the oldest...... and interpretations for iron and stony iron meteorites (Plate 13.1). Such meteorites provide important constraints on the nature of metal-silicate separation and mixing in planetesimals undergoing partial to complete differentiation. They include iron meteorites that formed by the solidification of cores...... (fractionally crystallized irons), irons in which partly molten metal and silicates of diverse types were mixed together (silicate-bearing irons), stony irons in which partly molten metal and olivine from cores and mantles were mixed together (pallasites), and stony irons in which partly molten metal...

Tuning the oxidative power of free iron-sulfur clusters.

Science.gov (United States)

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

2017-03-15

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

Electron small polarons and their mobility in iron (oxyhydr)oxide nanoparticles

DEFF Research Database (Denmark)

Katz, Jordan E; Zhang, Xiaoyi; Attenkofer, Klaus

2012-01-01

Electron mobility within iron (oxyhydr)oxides enables charge transfer between widely separated surface sites. There is increasing evidence that this internal conduction influences the rates of interfacial reactions and the outcomes of redox-driven phase transformations of environmental interest....... To determine the links between crystal structure and charge-transport efficiency, we used pump-probe spectroscopy to study the dynamics of electrons introduced into iron(III) (oxyhydr)oxide nanoparticles via ultrafast interfacial electron transfer. Using time-resolved x-ray spectroscopy and ab initio...

Effect of surfactant for magnetic properties of iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

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

2015-12-01

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

Beta-Thalassemia Major and Female Fertility: The Role of Iron and Iron-Induced Oxidative Stress

Science.gov (United States)

Roussou, Paraskevi; Tsagarakis, Nikolaos J.; Diamanti-Kandarakis, Evanthia

2013-01-01

Endocrine complications due to haemosiderosis are present in a significant number of patients with beta-thalassemia major (BTM) worldwide and often become barriers in their desire for parenthood. Thus, although spontaneous fertility can occur, the majority of females with BTM is infertile due to hypogonadotropic hypogonadism (HH) and need assisted reproductive techniques. Infertility in these women seems to be attributed to iron deposition and iron-induced oxidative stress (OS) in various endocrine organs, such as hypothalamus, pituitary, and female reproductive system, but also through the iron effect on other organs, such as liver and pancreas, contributing to the impaired metabolism of hormones and serum antioxidants. Nevertheless, the gonadal function of these patients is usually intact and fertility is usually retrievable. Meanwhile, a significant prooxidants/antioxidants imbalance with subsequent increased (OS) exists in patients with BTM, which is mainly caused by tissue injury due to overproduction of free radicals by secondary iron overload, but also due to alteration in serum trace elements and antioxidant enzymes. Not only using the appropriate antioxidants, essential trace elements, and minerals, but also regulating the advanced glycation end products, could probably reduce the extent of oxidative damage and related complications and retrieve BTM women's infertility. PMID:24396593

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

Science.gov (United States)

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

2017-02-08

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

Interactions of benzoic acid and phosphates with iron oxide colloids using chemical force titration.

Science.gov (United States)

Liang, Jana; Horton, J Hugh

2005-11-08

Colloidal iron oxides are an important component in soil systems and in water treatment processes. Humic-based organic compounds, containing both phenol and benzoate functional groups, are often present in these systems and compete strongly with phosphate species for binding sites on the iron oxide surfaces. Here, we examine the interaction of benzoate and phenolic groups with various iron oxide colloids using atomic force microscopy (AFM) chemical force titration measurements. Self-assembled monolayers (SAMs) of 4-(12-mercaptododecyloxy)benzoic acid and 4-(12-mercaptododecyloxy)phenol were used to prepare chemically modified Au-coated AFM tips, and these were used to probe the surface chemistry of a series of iron oxide colloids. The SAMs formed were also characterized using scanning tunneling microscopy, reflection-absorption infrared spectroscopy, and X-ray photoelectron spectroscopy. The surface pK(a) of 4-(12- mercaptododecyloxy)benzoic acid has been determined to be 4.0 +/- 0.5, and the interaction between the tip and the sample coated with a SAM of this species is dominated by hydrogen bonding. The chemical force titraton profile for an AFM probe coated with 4-(12- mercaptododecyloxy)benzoic acid and a bare iron oxide colloid demonstrates that the benzoic acid function group interacts with all three types of iron oxide sites present on the colloid surface over a wide pH range. Similar experiments were carried out on colloids precipitated in the presence of phosphoric, gallic, and tannic acids. The results are discussed in the context of the competitive binding interactions of solution species present in soils or in water treatment processes.

A general melt-injection-decomposition route to oriented metal oxide nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Han, Dongqiang; Zhang, Xinwei; Hua, Zhenghe; Yang, Shaoguang, E-mail: sgyang@nju.edu.cn

2016-12-30

Highlights: • A general melt-injection-decomposition (MID) route is proposed for the fabrication of oriented metal oxide nanowire arrays. • Four kinds of metal oxide (CuO, Mn{sub 2}O{sub 3}, Co{sub 3}O{sub 4} and Cr{sub 2}O{sub 3}) nanowire arrays have been realized as examples through the developed MID route. • The mechanism of the developed MID route is discussed using Thermogravimetry and Differential Thermal Analysis technique. • The MID route is a versatile, simple, facile and effective way to prepare different kinds of oriented metal oxide nanowire arrays in the future. - Abstract: In this manuscript, a general melt-injection-decomposition (MID) route has been proposed and realized for the fabrication of oriented metal oxide nanowire arrays. Nitrate was used as the starting materials, which was injected into the nanopores of the anodic aluminum oxide (AAO) membrane through the capillarity action in its liquid state. At higher temperature, the nitrate decomposed into corresponding metal oxide within the nanopores of the AAO membrane. Oriented metal oxide nanowire arrays were formed within the AAO membrane as a result of the confinement of the nanopores. Four kinds of metal oxide (CuO, Mn{sub 2}O{sub 3}, Co{sub 3}O{sub 4} and Cr{sub 2}O{sub 3}) nanowire arrays are presented here as examples fabricated by this newly developed process. X-ray diffraction, scanning electron microscopy and transmission electron microscopy studies showed clear evidence of the formations of the oriented metal oxide nanowire arrays. Formation mechanism of the metal oxide nanowire arrays is discussed based on the Thermogravimetry and Differential Thermal Analysis measurement results.

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

Indian Academy of Sciences (India)

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

Removal of oxides from alkali metal melts by reductive titration to electrical resistance-change end points

Science.gov (United States)

Tsang, Floris Y.

1980-01-01

Alkali metal oxides dissolved in alkali metal melts are reduced with soluble metals which are converted to insoluble oxides. The end points of the reduction is detected as an increase in electrical resistance across an alkali metal ion-conductive membrane interposed between the oxide-containing melt and a material capable of accepting the alkali metal ions from the membrane when a difference in electrical potential, of the appropriate polarity, is established across it. The resistance increase results from blocking of the membrane face by ions of the excess reductant metal, to which the membrane is essentially non-conductive.

Functionality of the iron oxides

International Nuclear Information System (INIS)

Castano, J.G.; Arroyave, C.

1998-01-01

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

Pentachlorophenol dechlorination with zero valent iron: a Raman and GCMS study of the complex role of surficial iron oxides.

Science.gov (United States)

Gunawardana, Buddhika; Swedlund, Peter J; Singhal, Naresh; Nieuwoudt, Michel K

2018-04-20

The dechlorination of chlorinated organic pollutants by zero valent iron (ZVI) is an important water treatment process with a complex dependence on many variables. This complexity means that there are reported inconsistencies in terms of dechlorination with ZVI and the effect of ZVI acid treatment, which are significant and are as yet unexplained. This study aims to decipher some of this complexity by combining Raman spectroscopy with gas chromatography-mass spectrometry (GC-MS) to investigate the influence of the mineralogy of the iron oxide phases on the surface of ZVI on the reductive dechlorination of pentachlorophenol (PCP). Two electrolytic iron samples (ZVI-T and ZVI-H) were found to have quite different PCP dechlorination reactivity in batch reactors under anoxic conditions. Raman analysis of the "as-received" ZVI-T indicated the iron was mainly covered with the ferrous oxide (FeO) wustite, which is non-conducting and led to a low rate of PCP dechlorination. In contrast, the dominant oxide on the "as-received" ZVI-H was magnetite which is conducting and, compared to ZVI-T, the ZVI-H rate of PCP dechlorination was four times faster. Treating the ZVI-H sample with 1 N H 2 SO 4 made small change to the composition of the oxide layers and also minute change to the rate of PCP dechlorination. However, treating the ZVI-T sample with H 2 SO 4 led to the loss of wustite so that magnetite became the dominant oxide and the rate of PCP dechlorination increased to that of the ZVI-H material. In conclusion, this study clearly shows that iron oxide mineralogy can be a contributing factor to apparent inconsistencies in the literature related to ZVI performance towards dechlorination and the effect of acid treatment on ZVI reactivity.

Lead-iron phosophate glass

International Nuclear Information System (INIS)

Sales, B.C.; Boatner, L.A.

1988-01-01

The lead-iron phosphate nuclear waste glasses (LIPNWG) are the subject of the present chapter. They were discovered in 1984 while the authors were attempting to find a sintering aid for certain types of crystalline monazite ceramic high-level nuclear waste forms. In the present chapter, the term waste glass is synonymous with nuclear waste glass (NWG), and the acronym LIP is often used for lead-iron phosphate. Lead-iron phosphate glasses, like many of the previously studied phosphate glasses, are corrosion resistant in aqueous solutions at temperatures below 100 degrees C, and they can be melted and poured at temperatures that are relatively low in comparison with the processing temperatures required for current silicate glass compositions. Unlike the phosphate glasses investigated previously, however, LIPNWGs do not suffer from alteration due to devitrification during realistic and readily, achievable cooling periods. Additionally, lead-iron phosphate glass melts are not nearly as corrosive as the sodium phosphate melts investigated during the 1960s; and, therefore, they can be melted and processed using crucibles made from a variety of materials

Oxidative degradation stability and hydrogen sulfide removal performance of dual-ligand iron chelate of Fe-EDTA/CA.

Science.gov (United States)

Miao, Xinmei; Ma, Yiwen; Chen, Zezhi; Gong, Huijuan

2017-09-05

Catalytic oxidation desulfurization using chelated iron catalyst is an effective method to remove H 2 S from various gas streams including biogas. However, the ligand of ethylenediaminetetraacetic acid (EDTA), which is usually adopted to prepare chelated iron catalyst, is liable to be oxidative degraded, and leads to the loss of desulfurization performance. In order to improve the degradation stability of the iron chelate, a series of iron chelates composed of two ligands including citric acid (CA) and EDTA were prepared and the oxidative degradation stability as well as desulfurization performance of these chelated iron catalysts were studied. Results show that the iron chelate of Fe-CA is more stable than Fe-EDTA, while for the desulfurization performance, the situation is converse. For the dual-ligand iron chelates of Fe-EDTA/CA, with the increase of mol ratio of CA to EDTA in the iron chelate solution, the oxidative degradation stability increased while the desulfurization performance decreased. The results of this work showed that Fe-EDTA/CA with a mol ratio of CA:EDTA = 1:1 presents a relative high oxidative degradation stability and an acceptable desulfurization performance with over 90% of H 2 S removal efficiency.

Behavior of concrete in contact with molten corium in the case of a hypothetical core melt accident

International Nuclear Information System (INIS)

Peehs, M.; Skokan, A.; Reimann, M.

1979-01-01

The temperature-dependent properties of basaltic and limestone concrete as needed for predicting Corium melt propagation in concrete (elongation behavior, specific heat and degradation enthalpy, thermal diffusivity, and conductivity) are determined experimentally together with the chemical and physical reactions occurring in heated concrete. The determined oxidation potential of -335 kJ/mole for molten Corium interacting with the concrete is in accordance with the observed H 2 generation due to the melt internal oxidation of zirconium, chromium, and iron. The liquefaction temperatures of the different concretes investigated are approx. 1300 to 1400 0 C. The relatively high degradation enthalpy of basaltic and limestone concrete is the reason for the barrier effect of concrete against propagating molten Corium

Films of double oxides of zirconium and iron

International Nuclear Information System (INIS)

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

2000-01-01

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

Role of iron oxide impurities in electrocatalysis by multiwall carbon

Indian Academy of Sciences (India)

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

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

Czech Academy of Sciences Publication Activity Database

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

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

Large-Scale Synthesis of Single-Crystalline Iron Oxide Magnetic Nanorings

DEFF Research Database (Denmark)

Jia, Chun-Jiang; Sun, Ling-Dong; Luo, Feng

2008-01-01

We present an innovative approach to the production of single-crystal iron oxide nanorings employing a solution-based route. Single-crystal hematite (alpha-Fe2O3) nanorings were synthesized using a double anion-assisted hydrothermal method (involving phosphate and sulfate ions), which can...... an intriguing three-dimensional magnetic configuration. This work provides an easily scaled-up method for preparing tailor-made iron oxide nanorings that could meet the demands of a variety of applications ranging from medicine to magnetoelectronics....... able to control the size, morphology, and surface architecture to produce a variety of three-dimensional hollow nanostructures. These can then be converted to magnetite (Fe3O4) and maghemite (gamma-Fe2O3) by a reduction or reduction-oxidation process while preserving the same morphology. The structures...

Selectivity and Activity of Iron Molybdate Catalysts in Oxidation of Methanol

OpenAIRE

Khalid Khazzal Hummadi; Karim H. Hassan; Phillip C.H. Mitchell

2009-01-01

The selectivity and activity of iron molybdate catalysts prepared by different methods are compared with those of a commercial catalyst in the oxidation of methanol to formaldehyde in a continuous tubular bed reactor at 200-350 oC (473-623 oK), 10 atm (1013 kPa), with a methanol-oxygen mixture fixed at 5.5% by volume methanol: air ratio. The iron(III) molybdate catalyst prepared by co-precipitation and filtration had a selectivity towards formaldehyde in methanol oxidation comparable with a c...

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-01-01

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Magnetic characteristics of ultrafine Fe particles reduced from uniform iron oxide particles

Science.gov (United States)

Bridger, K.; Watts, J.; Tadros, M.; Xiao, Gang; Liou, S. H.; Chien, C. L.

1987-04-01

Uniform, cubic 0.05-μm iron oxide particles were formed by forced hydrolysis of ferric perchlorate. These particles were reduced to α-Fe by heating in hydrogen at temperatures between 300 and 500 °C. The effect of reduction temperature and various prereduction treatments on the microstructure of the iron particles will be discussed. Complete reduction to α-Fe was established by 57Fe Mössbauer spectroscopy and x-ray diffraction. Magnetic measurements on epoxy and polyurethane films containing these particles with various mass fractions gave coercivities as high as 1000 Oe. The relationship between the magnetic measurements and the microstructure will be discussed. Na2SiO3 is found to be the best coating material for the process of reducing iron oxide particles to iron.

Nanocomposites of cellulose/iron oxide: influence of synthesis conditions on their morphological behavior and thermal stability