Sample records for nanophase ferric oxide

  1. High Resolution Transmission Electron Microscopy (HRTEM) of nanophase ferric oxides

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Iron oxide minerals are the prime candidates for Fe(III) signatures in remotely sensed Martian surface spectra. Magnetic, Mossbauer, and reflectance spectroscopy have been carried out in the laboratory in order to understand the mineralogical nature of Martian analog ferric oxide minerals of submicron or nanometer size range. Out of the iron oxide minerals studied, nanometer sized ferric oxides are promising candidates for possible Martian spectral analogs. 'Nanophase ferric oxide (np-Ox)' is a generic term for ferric oxide/oxihydroxide particles having nanoscale (less than 10 nm) particle dimensions. Ferrihydrite, superparamagnetic particles of hematite, maghemite and goethite, and nanometer sized particles of inherently paramagnetic lepidocrocite are all examples of nanophase ferric oxides. np-Ox particles in general do not give X-ray diffraction (XRD) patterns with well defined peaks and would often be classified as X-ray amorphous. Therefore, different np-Oxs preparations should be characterized using a more sensitive technique e.g., high resolution transmission electron microscopy (HRTEM). The purpose of this study is to report the particle size, morphology and crystalline order, of five np-Ox samples by HRTEM imaging and electron diffraction (ED).

  2. Mid-infrared transmission spectra of crystalline and nanophase iron oxides/oxyhydroxides and implications for remote sensing of Mars

    NASA Technical Reports Server (NTRS)

    Bell, James F., III; Roush, Ted L.; Morris, Richard V.

    1995-01-01

    Ferric-iron-bearing materials play an important role in the interpretation of visible to near-IR Mars spectra, and they may play a similarly important role in the analysis of new mid-IR spacecraft spectral observations to be obtained over the next decade. We review existing data on mid-IR transmission spectra of ferric oxides/oxyhydroxides and present new transmission spectra for ferric-bearing materials spanning a wide range of mineralogy and crystallinity. These materials include 11 samples of well-crystallized ferric oxides (hematite, maghemite, and magnetite) and ferric oxyhydroxides (goethite, lepidocrocite). We also report the first transmission spectra for purely nanophase ferric oxide samples that have been shown to exhibit spectral similarities to Mars in the visible to near-IR and we compare these data to previous and new transmission spectra of terrestrial palagonites. Most of these samples show numerous, diagnostic absorption features in the mid-IR due to Fe(3+)-O(2-) vibrational transitions, structural and/or bound OH, and/or silicates. These data indicate that high spatial resolution, moderate spectral resolution mid-IR ground-based and spacecraft observations of Mars may be able to detect and uniquely discriminate among different ferric-iron-bearing phases on the Martian surface or in the airborne dust.

  3. Mid-infrared transmission spectra of crystalline and nanophase iron oxides/oxyhydroxides and implications for remote sensing of Mars

    NASA Technical Reports Server (NTRS)

    Bell, James F., III; Roush, Ted L.; Morris, Richard V.

    1995-01-01

    Ferric-iron-bearing materials play an important role in the interpretation of visible to near-IR Mars spectra, and they may play a similarly important role in the analysis of new mid-IR spacecraft spectral observations to be obtained over the next decade. We review exisiting data on mid-IR transmission spectra of ferric oxides/oxyhydroxides and present new transmission spectra for ferric-bearing materials spanning a wide range of mineralogy and crystallinity. These materials include 11 samples of well-crystallized ferric oxides (hematite, maghemite, and magnetite) and ferric oxyhydroxides (goethite, lepidocrocite). We also report the first transmission spectra for purely nanophase ferric oxide samples that have been shown to exhibit spectral similarities to Mars in the visible to near-IR and we compare these data to previous and new transmission spectra of terrestial palagonites. Most of these samples show numerous, diagnostic absorption features in the mid-IR due to Fe(3+) - 0(2-) vibrational transitions, structural and/or bound OH, and/or silicates. These data indicate that high spatial resolution, moderate spectral resolution mid-IR ground-based and spacecraft observations of Mars may be able to detect and uniquely discriminate among different ferric-iron-bearing phases on the Martian surface or in the airborne dust.

  4. Nanophase Iron Oxides as an Ultraviolet Sunscreen for Ancient Photosynthetic Microbes: A Possible Link Between Early Organisms, Banded-Iron Formations, and the Oxygenation of the Atmosphere

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Rothschild, Lynn J.; Rothschild, Lynn J.; Rogoff, Dana A.

    2006-01-01

    We propose that nanophase iron oxide-bearing materials provided important niches for ancient photosynthetic microbes on the early Earth that ultimately led to the oxygenation of the Earth s atmosphere and the formation of iron oxide deposits. Atmospheric oxygen and ozone attenuate UV radiation on the Earth today providing substantial protection for photosynthetic organisms. With ultraviolet radiation fluxes likely to have been even higher on the early Earth than today, accessing solar radiation was particularly risky for early organisms. Yet, we know that photosynthesis arose then and played a critical role in subsequent evolution. Of primary importance was protection at approx.250-290 nm, where peak nucleic acid (approx.260 nm) and protein (approx.280 nm) absorptions occur. Nanophase ferric oxide/oxyhydroxide minerals absorb, and thus block, the lethal UV radiation, while transmitting light through much of the visible and near-infrared regions of interest to photosynthesis (400 to 1100 nm). Further, they were available in early environments, and are synthesized by many organisms. Based on ferric oxide/oxyhydroxide spectral properties, likely geologic processes, and the results of experiments with the photosynthetic organisms, Euglena sp. and Chlumydomonus reinhardtii, we propose a scenario where photosynthesis, and ultimately the oxygenation of the atmosphere, depended on the protection of early microbes by nanophase ferric oxides/oxyhydroxides. The results of this study are also applicable to other potentially habitable iron-bearing planetary bodies because of the evolutionary pressure to utilize solar radiation when available as an energy source.

  5. Optical determination of the oxygen stoichiometry of nanophase metal-oxide materials

    SciTech Connect

    Parker, J.C. (Nanophase Technologies Corp., Evanston, IL (USA)); Siegel, R.W. (Argonne National Lab., IL (USA))

    1990-10-01

    In this paper we present an overview and assessment of the use optical techniques, primarily Raman scattering, for analyzing the composition and stoichiometry of nanophase metal-oxide ceramics. Raman scattering has been shown to be a useful technique for evaluating the oxygen stoichiometry of some metal oxide materials. However, it is essential for nanophase materials that grain size effects are considered since their ultrafine grain sizes can produce large shifting and broadening of the Raman spectrum. 18 refs., 4 figs.

  6. Pigmenting agents in Martian soils: inferences from spectral, Mossbauer, and magnetic properties of nanophase and other iron oxides in Hawaiian palagonitic soil PN-9

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Golden, D. C.; Lauer, H. V. Jr; Adams, J. B.

    1993-01-01

    We have examined a Hawaiian palagonitic tephra sample (PN-9) that has spectroscopic similarities to Martian bright regions using a number of analytical techniques, including Mossbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge observed in Mossbauer and reflectivity spectra, respectively, for this and other spectrally similar palagonitic samples. The np-Ox particles appear to be imbedded in a hydrated aluminosilicate matrix material; no evidence was found for phyllosilicates. Other iron-bearing phases observed are titanomagnetite, which accounts for the magnetic nature of the sample; olivine; pyroxene; and glass. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.

  7. Transmission measurements (4000-400 cm(exp -1), 2.5-25 microns) of crystalline ferric oxides and ferric oxyhydroxides: Implications for Mars

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Bell, James F., III; Morris, Richard V.

    1994-01-01

    Transmission spectra of three ferric oxides (two alpha-Fe2O3 samples and one gamma-Fe2O3 sample) and two ferric oxyhydroxides (alpha-FeOOH and gamma-FeOOH) were measured. This preliminary study has demonstrated that crystalline ferric oxides and ferric oxyhydroxides exhibit complex spectral features at thermal wavelengths. Some of these features suggest that thermal infrared observations of Mars can provide significant insight into the ferric mineralogy of that planet. The results of this study suggest that emissivity spectra of crystalline ferric oxides and ferric oxyhydroxides may prove quite important for the interpretation of thermal infrared spectral observations of Mars.

  8. Lunar dust simulant containing nanophase iron and method for making the same

    NASA Technical Reports Server (NTRS)

    Hung, Chin-cheh (Inventor); McNatt, Jeremiah (Inventor)

    2012-01-01

    A lunar dust simulant containing nanophase iron and a method for making the same. Process (1) comprises a mixture of ferric chloride, fluorinated carbon powder, and glass beads, treating the mixture to produce nanophase iron, wherein the resulting lunar dust simulant contains .alpha.-iron nanoparticles, Fe.sub.2O.sub.3, and Fe.sub.3O.sub.4. Process (2) comprises a mixture of a material of mixed-metal oxides that contain iron and carbon black, treating the mixture to produce nanophase iron, wherein the resulting lunar dust simulant contains .alpha.-iron nanoparticles and Fe.sub.3O.sub.4.

  9. Ferric oxide quantum dots in stable phosphate glass system and their magneto-optical study

    SciTech Connect

    Garaje, Sunil N.; Apte, Sanjay K. [Nanocomposite Group, Centre for Materials for Electronics Technology (C-MET), Department of Electronics and Information Technology (DeitY), Government of India, Panchawati, Off Pashan Road, Pune 411008 (India)] [Nanocomposite Group, Centre for Materials for Electronics Technology (C-MET), Department of Electronics and Information Technology (DeitY), Government of India, Panchawati, Off Pashan Road, Pune 411008 (India); Kumar, Ganpathy [Department of Electrical and Computer Engineering, Tennessee Technological University, 1 William L. Jones Drive, Cookeville, TN 38505 (United States)] [Department of Electrical and Computer Engineering, Tennessee Technological University, 1 William L. Jones Drive, Cookeville, TN 38505 (United States); Panmand, Rajendra P.; Naik, Sonali D. [Nanocomposite Group, Centre for Materials for Electronics Technology (C-MET), Department of Electronics and Information Technology (DeitY), Government of India, Panchawati, Off Pashan Road, Pune 411008 (India)] [Nanocomposite Group, Centre for Materials for Electronics Technology (C-MET), Department of Electronics and Information Technology (DeitY), Government of India, Panchawati, Off Pashan Road, Pune 411008 (India); Mahajan, Satish M., E-mail: smahajan@tntech.edu [Department of Electrical and Computer Engineering, Tennessee Technological University, 1 William L. Jones Drive, Cookeville, TN 38505 (United States); Chand, Ramesh [Ministry of Communications and Information Technology, Department of Electronics and Information Technology (DeitY), Electronics Niketan, 6, CGO Complex, New Delhi 110003 (India)] [Ministry of Communications and Information Technology, Department of Electronics and Information Technology (DeitY), Electronics Niketan, 6, CGO Complex, New Delhi 110003 (India); Kale, Bharat B., E-mail: bbkale@cmet.gov.in [Nanocomposite Group, Centre for Materials for Electronics Technology (C-MET), Department of Electronics and Information Technology (DeitY), Government of India, Panchawati, Off Pashan Road, Pune 411008 (India)

    2013-02-15

    Graphical abstract: We report synthesis of ferric oxide embedded low melting phosphate glass nanocomposite and also the effect of ferric oxide nanoparticles (NCs) content on the optical and magneto-optical properties of the glasses. Faraday rotation of the glass nanocomposites was measured and showed variation in Verdet constant with concentration of ferric oxide. Interestingly, the host glass itself showed fairly good Verdet constant (11.5°/T cm) and there is a threefold enhancement in the Verdet constant of ferric oxide quantum dot-glass nanocomposite. Highlights: ? We synthesize ferric oxide embedded low melting stable phosphate glass nanocomposite. ? Glasses doped with 0.25 and 2% ferric oxide show particle size in the range of 4–12 nm. ? The host phosphate glass itself shows fairly good Verdet constant (11.5°/T cm). ? Glasses doped with 0.25% ferric oxide show high Verdet constant (30.525°/T cm). ? The as synthesis glasses may have potential application in magneto optical devices. -- Abstract: Herein, we report the synthesis of ferric oxide embedded low melting phosphate glass nanocomposite and also the effect of ferric oxide nanoparticles content on the optical and magneto-optical properties of the glasses. The optical study clearly showed red shift in optical cut off with increasing ferric oxide concentration. The band gap of the host glass was observed to be 3.48 eV and it shifted to 3.14 eV after doping with ferric oxide. The glasses doped with 0.25 and 2% ferric oxide showed particle size of 4–6 nm and 8–12 nm, respectively. Faraday rotation of the glass nanocomposites was measured and showed variation in the Verdet constant as per increasing concentration of ferric oxide. Interestingly, the host glass itself showed fairly good Verdet constant (11.5°/T cm) and threefold enhancement was observed in the Verdet constant of ferric oxide quantum dot-glass nanocomposite.

  10. 21 CFR 186.1300 - Ferric oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...hematite. It may be prepared synthetically by heating brown iron hydroxide oxide. The product is red-brown to black trigonal crystals. (b) In accordance with § 186.1(b)(1), the ingredient is used as an indirect human food ingredient...

  11. 21 CFR 186.1300 - Ferric oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...hematite. It may be prepared synthetically by heating brown iron hydroxide oxide. The product is red-brown to black trigonal crystals. (b) In accordance with § 186.1(b)(1), the ingredient is used as an indirect human food ingredient...

  12. Acoustical investigations of borate glasses containing oxides of some transition elements and ferric oxide dopants

    Microsoft Academic Search

    Surjit Singh Bhatti; Kanwar Jit Singh

    2003-01-01

    Glass samples of manganese oxide borate and zinc oxide borate (with and without ferric oxide doping) have been prepared to study their acoustical, mechanical, and thermal behavior as function of composition. Sound velocities and attenuation measurements in these glass systems at 1,2, and 5 MHz give elastic moduli, Poissons ratio, micro-hardness, acoustic impedance, internal friction, thermal expansion coefficient and Debye

  13. Rapidly reversible redox transformation in nanophase manganese oxides at room temperature triggered by changes in hydration

    PubMed Central

    Birkner, Nancy; Navrotsky, Alexandra

    2014-01-01

    Chemisorption of water onto anhydrous nanophase manganese oxide surfaces promotes rapidly reversible redox phase changes as confirmed by calorimetry, X-ray diffraction, and titration for manganese average oxidation state. Surface reduction of bixbyite (Mn2O3) to hausmannite (Mn3O4) occurs in nanoparticles under conditions where no such reactions are seen or expected on grounds of bulk thermodynamics in coarse-grained materials. Additionally, transformation does not occur on nanosurfaces passivated by at least 2% coverage of what is likely an amorphous manganese oxide layer. The transformation is due to thermodynamic control arising from differences in surface energies of the two phases (Mn2O3 and Mn3O4) under wet and dry conditions. Such reversible and rapid transformation near room temperature may affect the behavior of manganese oxides in technological applications and in geologic and environmental settings. PMID:24733903

  14. High pressure structural studies on nanophase praseodymium oxide

    NASA Astrophysics Data System (ADS)

    Saranya, L.; Chandra Shekar, N. V.; Amirthapandian, S.; Hussain, Shamima; Arulraj, A.; Sahu, P. Ch.

    2014-09-01

    The phase stability of nanocrystalline Pr2O3 has been investigated under pressure by in-situ high pressure X-ray diffraction using Mao-Bell type diamond anvil cell. The ambient structure and phase of the praseodymium oxide have been resolved unambiguously using x-ray diffraction, SEM and TEM techniques. Under the action of pressure the cubic phase of the system is retained up to 15 GPa. This is unusual as other isostructural rare earth oxides show structural transformations even at lower pressures. From the best fit to the P-V data with the Murnaghan equation of state yields a bulk modulus of 171 GPa.

  15. Magnetotactic bacteria form magnetite from a phosphate-rich ferric hydroxide via nanometric ferric (oxyhydr)oxide intermediates.

    PubMed

    Baumgartner, Jens; Morin, Guillaume; Menguy, Nicolas; Perez Gonzalez, Teresa; Widdrat, Marc; Cosmidis, Julie; Faivre, Damien

    2013-09-10

    The iron oxide mineral magnetite (Fe3O4) is produced by various organisms to exploit magnetic and mechanical properties. Magnetotactic bacteria have become one of the best model organisms for studying magnetite biomineralization, as their genomes are sequenced and tools are available for their genetic manipulation. However, the chemical route by which magnetite is formed intracellularly within the so-called magnetosomes has remained a matter of debate. Here we used X-ray absorption spectroscopy at cryogenic temperatures and transmission electron microscopic imaging techniques to chemically characterize and spatially resolve the mechanism of biomineralization in those microorganisms. We show that magnetite forms through phase transformation from a highly disordered phosphate-rich ferric hydroxide phase, consistent with prokaryotic ferritins, via transient nanometric ferric (oxyhydr)oxide intermediates within the magnetosome organelle. This pathway remarkably resembles recent results on synthetic magnetite formation and bears a high similarity to suggested mineralization mechanisms in higher organisms. PMID:23980143

  16. Magnetotactic bacteria form magnetite from a phosphate-rich ferric hydroxide via nanometric ferric (oxyhydr)oxide intermediates

    PubMed Central

    Baumgartner, Jens; Morin, Guillaume; Menguy, Nicolas; Perez Gonzalez, Teresa; Widdrat, Marc; Cosmidis, Julie; Faivre, Damien

    2013-01-01

    The iron oxide mineral magnetite (Fe3O4) is produced by various organisms to exploit magnetic and mechanical properties. Magnetotactic bacteria have become one of the best model organisms for studying magnetite biomineralization, as their genomes are sequenced and tools are available for their genetic manipulation. However, the chemical route by which magnetite is formed intracellularly within the so-called magnetosomes has remained a matter of debate. Here we used X-ray absorption spectroscopy at cryogenic temperatures and transmission electron microscopic imaging techniques to chemically characterize and spatially resolve the mechanism of biomineralization in those microorganisms. We show that magnetite forms through phase transformation from a highly disordered phosphate-rich ferric hydroxide phase, consistent with prokaryotic ferritins, via transient nanometric ferric (oxyhydr)oxide intermediates within the magnetosome organelle. This pathway remarkably resembles recent results on synthetic magnetite formation and bears a high similarity to suggested mineralization mechanisms in higher organisms. PMID:23980143

  17. Dietary bioavailability of Cu adsorbed to colloidal hydrous ferric oxide

    USGS Publications Warehouse

    Cain, Daniel J.; Croteau, Marie-Noële; Fuller, Christopher C.

    2013-01-01

    The dietary bioavailability of copper (Cu) adsorbed to synthetic colloidal hydrous ferric oxide (HFO) was evaluated from the assimilation of 65Cu by two benthic grazers, a gastropod and a larval mayfly. HFO was synthesized, labeled with 65Cu to achieve a Cu/Fe ratio comparable to that determined in naturally formed HFO, and then aged. The labeled colloids were mixed with a food source (the diatom Nitzschia palea) to yield dietary 65Cu concentrations ranging from 211 to 2204 nmol/g (dry weight). Animals were pulse fed the contaminated diet and assimilation of 65Cu from HFO was determined following 1–3 days of depuration. Mass transfer of 65Cu from HFO to the diatom was less than 1%, indicating that HFO was the source of 65Cu to the grazers. Estimates of assimilation efficiency indicated that the majority of Cu ingested as HFO was assimilated (values >70%), implying that colloidal HFO potentially represents a source of dietary Cu to benthic grazers, especially where there is active formation and infiltration of these particles into benthic substrates.

  18. RATES OF HYDROUS FERRIC OXIDE CRYSTALLIZATION AND THE INFLUENCE ON COPRECIPITATED ARSENATE: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-ADA-02101 Ford*, R. Rates of Hydrous Ferric Oxide Crystallization and the Influence on Coprecipitated Arsenate. Environmental Science & Technology 36 (11):2459-2463 (2002). EPA/600/J-02/240. Arsenate coprecipitated with hydrous fer...

  19. Iron oxidation and precipitation of ferric hydroxysulfates by resting Thiobacillus ferrooxidans cells

    Microsoft Academic Search

    N. Lazaroff; W. Sigal; A. Wasserman

    1982-01-01

    The oxidation of ferrous ions, in acid solution, by resting suspensions of Thiobacillus ferrooxidans produced sediments consisting of crystalline jarosites, amorphous ferric hydroxysulfates, or both. These products differed conspicuously in chemical composition and infrared spectra from precipitates formed by abiotic oxidation under similar conditions. The amorphous sediments, produced by bacterial oxidation, exhibited a distinctive fibroporous microstructure when examined by scanning

  20. Structural and optical studies of nickel-cobalt-ferric oxides nanocomposite

    NASA Astrophysics Data System (ADS)

    Devadathan, Dedhila; Raveendran, R.

    2015-02-01

    In this study single salts of nickel oxide, cobalt oxide, ferric oxide and the nanocomposite of nickel-cobalt-ferric oxide was prepared by the well-known co-precipitation method. The samples were annealed at different temperatures and were characterized using SEM, EDAX, TGA, FTIR, XRD, UV and Photo luminescence (PL). UV analysis showed that the nanocomposite can be suitably tuned to a wide band gap material. The Photo Luminescence analysis showed that the nanocomposite can be used as light emitters in visible region.

  1. Interaction of nanoparticles of ferric oxide with brain nerve terminals and blood platelets

    NASA Astrophysics Data System (ADS)

    Borisova, Tatiana; Krisanova, Natalia; Sivko, Roman; Borisov, Arseniy

    2012-07-01

    Nanoparticles of ferric oxide are the components of Lunar and Martian soil simulants. The observations suggest that exposure to Lunar soli simulant can be deleterious to human physiology and the components of lunar soil may be internalized by lung epithelium and may overcome the blood-brain barrier. The study focused on the effects of nanoparticles of ferric oxide on the functional state of rat brain nerve terminals (synaptosomes) and rabbit blood platelets. Using photon correlation spectroscopy, we demonstrated the binding of nanoparticles of ferric oxide with nerve terminals and platelets. Nanoparticles did not depolarize the plasma membrane of nerve terminals and platelets that was shown by fluorimetry with potential-sensitive fluorescent dye rhodamine 6G. Using pH-sensitive fluorescent dye acridine orange, we revealed that the acidification of synaptic vesicles of nerve terminals and secretory granules of platelets did not change in the presence of nanoparticles. The initial velocity of uptake of excitatory neurotransmitter glutamate was not influenced by nanoparticles of ferric oxide, whereas glutamate binding to nerve terminals was altered. Thus, it was suggested that nanoparticles of ferric oxide might disturb glutamate transport in the mammalian CNS.

  2. RATES OF HYDROUS FERRIC OXIDE CRYSTALLIZATION AND THE INFLUENCE ON COPRECIPITATED ARSENATE

    EPA Science Inventory

    Arsenate coprecipitated with hydrous ferric oxide (HFO) was stabilized against dissolution during transformation of HFO to more crystalline iron (hydr)oxides. The rate of arsenate stabilization approximately coincided with the rate of HFO transformation at pH 6 and 40 ?C. Compa...

  3. Complexation of ferric oxide particles with pectins of ordered and random distribution of charged units

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Complexation between ferric oxide particles and pectins with degree of methylation 50%, but having blockwise (ordered) or random arrangement of free carboxyl groups, are investigated by electric light scattering and electrophoresis. The influence of charge distribution in pectin chain on the electri...

  4. Aqueous pyrite oxidation by dissolved oxygen and by ferric iron

    Microsoft Academic Search

    C. O. Moses; D. K. Nordstrom; J. S. Herman; A. L. Mills

    1987-01-01

    Rates of aqueous, abiotic pyrite oxidation were measured in oxygen-saturated and anaerobic Fe(III)-saturated solutions with initial pH from 2 to 9. These studies included analyses of sulfite, thiosulfate, polythionates, and sulfate, and procedures for cleaning oxidation products from pyrite surfaces were evaluated. Pyrite oxidation in oxygen-saturated solutions produced (1) rates that were only slightly dependent on initial pH, (2) linear

  5. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation

    PubMed Central

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H.; Navrotsky, Alexandra

    2013-01-01

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

  6. Sulfates, Ferric Oxides and Al-OH Bearing Minerals in Aram Chaos

    NASA Astrophysics Data System (ADS)

    Masse, M.; Bourgeois, O.; Le Mouelic, S.; Le Deit, L.; Verpoorter, C.; Combe, J.; Sotin, C.; Bibring, J.; Gondet, B.; Langevin, Y.

    2008-12-01

    Aram Chaos is a 280 km wide Martian crater centered at 2.5N, 338.5E. This crater is filled by chaotic terrains, overlain by a presently dome-shaped layered, 900 m thick formation, displaying spectral signatures of ferric oxides and sulfates on TES and OMEGA data (Glotch et al. 2005, JGR 110, E09006). In a previous study (Masse et al. 2008, JGR in press), using OMEGA, MOLA, MOC, TES, THEMIS and CTX data, we proposed that the presently dome-shaped formation is composed of a bright material that contains both monohydrated sulfates and ferric oxides. After its emplacement, this formation has been grooved down to various depths by large aeolian erosion corridors. The borders of the corridors are steep linear cliffs where the bright, layered, sulfate-rich material crops out. These cliffs are also partially covered by dark debris fans, which originate from the bright formation itself and which feed dark sand sheets covering the lowest stratigraphic levels of the bright formation. We therefore infer that the dark ferric oxide sand sheets and debris fans are erosional products of the bright formation. We therefore infer that the dark ferric oxide sand sheets and debris fans are erosional products of the bright formation. Due to the relatively low spatial resolution of OMEGA, it is not possible to analyse the exact composition of the cliffs. The aim of the present work is to refine these results and to compare them with newly acquired, high resolution, hyperspectral data from the Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). CRISM data confirm the mineralogical conclusions made with OMEGA data. Moreover, CRISM data allow the detection of a new layer, containing an Al-OH bearing mineral, at the bottom of this dome-shaped formation.

  7. Nanonails structured ferric oxide thick film as room temperature liquefied petroleum gas (LPG) sensor

    NASA Astrophysics Data System (ADS)

    Yadav, B. C.; Singh, Satyendra; Yadav, Anuradha

    2011-01-01

    In the present work, ferric oxide nanonails were prepared by screen printing method on borosilicate glass substrate and their electrical and LPG sensing properties were investigated. The structural and morphological characterizations of the material were analyzed by means of X-ray diffraction (XRD) and Scanning electron microscopy (SEM). XRD pattern revealed crystalline ?-phase and rhombohedral crystal structure. SEM images show nanonails type of morphology throughout the surface. Optical characterization of the film was carried out by UV-visible spectrophotometer. By Tauc plot the estimated value of band gap of film was found 3.85 eV. The LPG sensing properties of the ferric oxide film were investigated at room temperature for different vol.% of LPG. The variations in electrical resistance of the film were measured with the exposure of LPG as a function of time. The maximum values of sensitivity and sensor response factors were found 51 and 50 respectively for 2 vol.% of LPG. The activation energy calculated from Arrhenius plot was found 0.95 eV. The response and recovery time of sensing film were found ˜120 s and 150 s respectively. These experimental results show that nanonails structured ferric oxide is a promising material as LPG sensor.

  8. Iron Oxidation and Precipitation of Ferric Hydroxysulfates by Resting Thiobacillus ferrooxidans Cells.

    PubMed

    Lazaroff, N; Sigal, W; Wasserman, A

    1982-04-01

    The oxidation of ferrous ions, in acid solution, by resting suspensions of Thiobacillus ferrooxidans produced sediments consisting of crystalline jarosites, amorphous ferric hydroxysulfates, or both. These products differed conspicuously in chemical composition and infrared spectra from precipitates formed by abiotic oxidation under similar conditions. The amorphous sediments, produced by bacterial oxidation, exhibited a distinctive fibroporous microstructure when examined by scanning electron microscopy. Infrared spectra indicated outer-sphere coordination of Fe(III) by sulfate ions, as well as inner-sphere coordination by water molecules and bridging hydroxo groups. In the presence of excess sulfate and appropriate monovalent cations, jarosites, instead of amorphous ferric hydroxysulfates, precipitated from bacterially oxidized iron solutions. It is proposed that the jarositic precipitates result from the conversion of outer-sphere (T(d)) sulfate, present in a soluble polymeric Fe(III) complex, to inner-sphere (C(3v)) bridging sulfate. The amorphous precipitates result from the further polymerization of hydroxo-linked iron octahedra and charge stabilized aggregation of the resulting iron complexes in solution. This view was supported by observations that bacterially oxidized iron solutions gave rise to either amorphous or jarositic sediments in response to ionic environments imposed after oxidation had been completed and the bacteria had been removed by filtration. PMID:16345996

  9. Iron oxidation and precipitation of ferric hydroxysulfates by resting Thiobacillus ferrooxidans cells

    SciTech Connect

    Lazaroff, N.; Sigal, W.; Wasserman, A.

    1982-04-01

    The oxidation of ferrous ions, in acid solution, by resting suspensions of Thiobacillus ferrooxidans produced sediments consisting of crystalline jarosites, amorphous ferric hydroxysulfates, or both. These products differed conspicuously in chemical composition and infrared spectra from precipitates formed by abiotic oxidation under similar conditions. The amorphous sediments, produced by bacterial oxidation, exhibited a distinctive fibroporous microstructure when examined by scanning electron microscopy. Infrared spectra indicated outersphere coordination of Fe(III) by sulfate ions, as well as inner-sphere coordination by water molecules and bridging hydroxo groups. In the presence of excess sulfate and appropriate monovalent cations, jarosites, instead of amorphous ferric hydroxysulfates, precipitated from bacterially oxidized iron solutions. It is proposed that the jarositic precipitates result from the conversion of outer-sphere (T/sub d/) sulfate, present in a soluble polymeric Fe(III) complex, to inner-sphere (C/sub 3//sub v/) bridging sulfate. The amorphous precipitates result from the further polymerization of hydroxo-linked iron octahedra and charge stabilized aggregation of the resulting iron complexes in solution. This view was supported by observations that bacterially oxidized iron solutions gave rise to either amorphous or jarositic sediments in response to ionic environments imposed after oxidation had been completed and the bacteria had been removed by filtration.

  10. Iron Oxidation and Precipitation of Ferric Hydroxysulfates by Resting Thiobacillus ferrooxidans Cells

    PubMed Central

    Lazaroff, Norman; Sigal, Warren; Wasserman, Andrew

    1982-01-01

    The oxidation of ferrous ions, in acid solution, by resting suspensions of Thiobacillus ferrooxidans produced sediments consisting of crystalline jarosites, amorphous ferric hydroxysulfates, or both. These products differed conspicuously in chemical composition and infrared spectra from precipitates formed by abiotic oxidation under similar conditions. The amorphous sediments, produced by bacterial oxidation, exhibited a distinctive fibroporous microstructure when examined by scanning electron microscopy. Infrared spectra indicated outer-sphere coordination of Fe(III) by sulfate ions, as well as inner-sphere coordination by water molecules and bridging hydroxo groups. In the presence of excess sulfate and appropriate monovalent cations, jarosites, instead of amorphous ferric hydroxysulfates, precipitated from bacterially oxidized iron solutions. It is proposed that the jarositic precipitates result from the conversion of outer-sphere (Td) sulfate, present in a soluble polymeric Fe(III) complex, to inner-sphere (C3v) bridging sulfate. The amorphous precipitates result from the further polymerization of hydroxo-linked iron octahedra and charge stabilized aggregation of the resulting iron complexes in solution. This view was supported by observations that bacterially oxidized iron solutions gave rise to either amorphous or jarositic sediments in response to ionic environments imposed after oxidation had been completed and the bacteria had been removed by filtration. Images PMID:16345996

  11. Room temperature electrodeposition and characterization of bismuth ferric oxide (BFO) thin films from aqueous nitrate bath

    NASA Astrophysics Data System (ADS)

    Gujar, T. P.; Shinde, V. R.; Kulkarni, S. S.; Pathan, H. M.; Lokhande, C. D.

    2006-03-01

    Bismuth ferric oxide (BFO) thin films were prepared on fluorine doped tin oxide (FTO) coated glass substrates using electrodeposition method from aqueous nitrate bath at room temperature. The various preparative parameters, such as bath composition, current density, deposition time, etc were optimized to get good quality BFO thin films. The structural, surface morphological, optical and dielectrical properties of the films were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), optical absorption and dielectric measurement techniques. The results show that electrodeposition method allows to synthesis BFO films. The films are free from pinholes and cracks. The magnitudes of dielectric constant and loss tangent showed inverse frequency dependence.

  12. Arsenate sorption by hydrous ferric oxide incorporated onto granular activated carbon with phenol formaldehyde resins coating.

    PubMed

    Zhuang, J M; Hobenshield, E; Walsh, T

    2008-04-01

    A simple and effective method was developed using phenol formaldehyde (PF) resins to immobilize hydrous ferric oxide (HFO) onto granular activated carbon (GAC). The resulting sorbent possesses advantages for both the ferric oxide and the GAC, such as a great As-affinity of ferric oxide, large surface area of GAC, and enhanced physical strength. The studies showed that within one hour this sorbent was able to remove 85% of As(V) from water containing an initial As(V) concentration of 1.74 mg l(-1). The As(V) adsorption onto the sorbent was found to follow a pseudo-second order kinetics model. The adsorption isotherms were interpreted in terms of the Langmuir and Freundlich models. The equilibrium data fitted very well to both models. Column tests showed that this sorbent was able to achieve residual concentrations of As(V) in a range of 0.1-2.0 microg l(-1) while continuously treating about 180 bed volume (BV, 130 ml-BV) of arsenate water with an initial As(V) concentration of 1886 microg l(-1) at a filtration rate of 13.5 ml min(-1), i.e., an empty bed contact time (EBCT) of 9.6 min and a gram sorbent contact time (GSCT) of 0.15 min. After passing 635 BV of arsenate water, the exhausted sorbent was then tested by the Toxicity Characteristic Leaching Procedure (TCLP, US EPA Method 1311) test, and classified as non-hazardous for disposal. Hence, this HFO-PF-coated GAC has the capability to remove As(V) from industrial wastewater containing As(V) levels of about 2 mg l(-1). PMID:18619145

  13. Arsenic and antimony removal from drinking water by adsorption on granular ferric oxide.

    PubMed

    Sazakli, Eleni; Zouvelou, Stavroula V; Kalavrouziotis, Ioannis; Leotsinidis, Michalis

    2015-01-01

    Arsenic and antimony occur in drinking water due to natural weathering or anthropogenic activities. There has been growing concern about their impact on health. The aim of this study was to assess the efficiency of a granular ferric oxide adsorbent medium to remove arsenic and antimony from drinking water via rapid small-scale column tests (RSSCTs). Three different water matrices - deionized, raw water treated with a reverse osmosis domestic device and raw water - were spiked with arsenic and/or antimony to a concentration of 100 ?g L(-1). Both elements were successfully adsorbed onto the medium. The loadings until the guideline value was exceeded in the effluent were found to be 0.35-1.63 mg g(-1) for arsenic and 0.12-2.11 mg g(-1) for antimony, depending on the water matrix. Adsorption of one element was not substantially affected by the presence of the other. Aeration did not affect significantly the adsorption capacity. Granular ferric oxide could be employed for the simultaneous removal of arsenic and antimony from drinking water, whereas full-scale systems should be assessed via laboratory tests before their implementation. PMID:25746656

  14. A Beverage Containing Fermented Black Soybean Ameliorates Ferric Nitrilotriacetate-Induced Renal Oxidative Damage in Rats

    PubMed Central

    Okazaki, Yasumasa; Iqbal, Mohammad; Kawakami, Norito; Yamamoto, Yorihiro; Toyokuni, Shinya; Okada, Shigeru

    2010-01-01

    It is beneficial to seek scientific basis for the effects of functional foods. Natural pigments derived from plants are widely known as possible antioxidants. Black soybean contains a larger amount of anthocyanins than regular soybean. Here we studied the antioxidative effect of a beverage obtained via citric acid fermentation of black soybean (BBS), using a rat model of renal oxidative injury induced by a renal carcinogen, ferric nitrilotriacetate. BBS (10 ml/kg) was orally administered 30 min before ferric nitrilotriacetate treatment. Renal lipid peroxidation was significantly suppressed in the BBS-pretreated animals concomitant with decrease in 4-hydroxy-2-nonenal-modified proteins and 8-hydroxy-2'-deoxyguanosine. Maintenance of renal activities of antioxidative enzymes including catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, glucose-6-phosphate dehydrogenase and quinone reductase was significantly better in the BBS-pretreated rats. Elevation of serum creatinine and urea nitrogen was significantly suppressed in the BBS-pretreated rats. These data suggest that dietary intake of BBS is useful for the prevention of renal tubular oxidative damage mediate by iron, and warrant further investigation. PMID:21103028

  15. Moessbauer search for ferric oxide phases in lunar materials and simulated lunar materials

    NASA Technical Reports Server (NTRS)

    Forester, D. W.

    1973-01-01

    Moessbauer studies were carried out on lunar fines and on simulated lunar glasses containing magnetic-like precipitates with the primary objective of determining how much, if any, ferric oxide is present in the lunar soils. Although unambiguous evidence of lunar Fe(3+) phases was not obtained, an upper limit was estimated from different portions of the Moessbauer spectra to be between 0.1 and 0.4 wt.% (as Fe3O4). A smaller than 62 microns fraction of 15021,118 showed 0.5 wt.% ferromagnetic iron at 300 K in as-returned condition. After heating to 650 C in an evacuated, sealed quartz tube for 1400 hours, the same sample exhibited 1 wt.% ferromagnetic iron at room temperature. An accompanying decrease in excess absorption area near zero velocity was noted. Thus, the result of the vacuum heat treatment was to convert fine grained iron to larger particles, apparently without the oxidation effects commonly reported.

  16. ELSEVIER Earth and PlanetaryScienceLetters 123(1994)205-220 Ferric iron in peridotites and mantle oxidation states

    E-print Network

    Rudnick, Roberta L.

    ELSEVIER Earth and PlanetaryScienceLetters 123(1994)205-220 EPSL Ferric iron in peridotites characterized pyroxenite and peridotite xenoliths from central France, southeastern Australia, northern Tanzania in peridotites. For this reason, the oxidation states of upper mantle peridotites should not generally

  17. Abstract No. pan0505 Sorption of Heavy Metal Contaminants onto Hydrated Ferric Oxides: Mechanistic Modeling using X-ray

    E-print Network

    Sparks, Donald L.

    Abstract No. pan0505 Sorption of Heavy Metal Contaminants onto Hydrated Ferric Oxides: Mechanistic the fate of heavy metal contaminants, such as lead, zinc, and nickel in soils and aquatic environments. Hence, to understand the mobility and bioavailability of these metal contaminants, these sorption

  18. Carcinogenicity of Benzo(a)Pyrene and Dusts in the Hamster Lung (Instilled Intratracheally with Titanium Oxide, Aluminum Oxide, Carbon and Ferric Oxide)

    Microsoft Academic Search

    F. Stenbäck; J. Rowland; A. Sellakumar

    1976-01-01

    The possible carcinogenic or fibrogenic effects of intratracheal instillation of a polycyclic hydrocarbon, benzo(a) pyrene (B(a)P), alone or in combination with several dusts – titanium dioxide (TiO2), aluminum oxide (AI2O3), carbon (C) and ferric oxide (Fe2O3) – were investigated in hamsters. When administered alone, the dusts induced interstitial cell proliferation, bronchial epithelial alterations and a few granulomatous changes in the

  19. Biogenic iron mineralization accompanying the dissimilatory reduction of hydrous ferric oxide by a groundwater bacterium

    SciTech Connect

    Fredrickson, J.K.; Zachara, J.M.; Kennedy, D.W.; Li, S.M. [Pacific Northwest National Lab., Richland, WA (United States)] [Pacific Northwest National Lab., Richland, WA (United States); Dong, H.; Onstott, T.C. [Princeton Univ., NJ (United States). Dept. of Geosciences] [Princeton Univ., NJ (United States). Dept. of Geosciences; Hinman, N.W. [Univ. of Montana, Missoula, MT (United States). Dept. of Geology] [Univ. of Montana, Missoula, MT (United States). Dept. of Geology

    1998-10-01

    The purpose of this research was to investigate the bacterial reduction of hydrous ferric oxide (HFO) by Shewanella putrefaciens and the nature of biogenic secondary phase formation in the presence of different inorganic ligands (PO{sub 4} and HCO{sub 3}) under conditions that may promote or suppress the organism/oxide association (i.e., with and without an electron shuttle). The electron shuttle used, anthraquinone-2,6-disulfonate (AQDS), is both a humic acid analog and a soluble redox indicator. The goal was to provide insights on biogeochemical factors governing dissimilatory biogenic mineralization in sediment or groundwater systems. The authors have investigated the influence of AQDS on the rate and extent of HFO reduction in different buffered systems and utilized X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to evaluate the crystallographic and morphologic features of the biogenic precipitates. The biogenic phase association is interpreted in light of aqueous solution conditions, pe, solid phase thermodynamic stability, and microbiological considerations including metabolic status and growth with the intent of identifying unique microbiological contributions to secondary mineralization.

  20. Effect of oxidative stress on the pharmacokinetics of clomipramine in rats treated with ferric-nitrilotriacetate.

    PubMed

    Kobuchi, Shinji; Fukushima, Keizo; Aoyama, Hiroaki; Matsuda, Tatsuma; Ito, Yukako; Sugioka, Nobuyuki; Takada, Kanji

    2011-12-01

    The effect of oxidative stress (OS) on the pharmacokinetics of clomipramine (CPM), particularly addressing the change of CPM distribution to plasma components, was studied in ferric-nitrilotriacetate-induced oxidative-stress model rats (OS rats). First, CPM pharmacokinetic studies in OS rats were performed using CPM continuous infusion (17.5 ?g/min/kg). Plasma concentration of CPM at a steady state in OS rats (0.20 ± 0.02 ?g/mL) was significantly lower than that in control rats (0.30 ± 0.02 ?g/mL). However, no difference was found in the amounts of CPM in the brains of control rats (1.67 ± 0.13 ?g/g) and OS rats (1.63 ± 0.09 ?g/g). Both of plasma unbound fraction and distribution to erythrocytes in OS rats were significantly higher than those of control rats. These results suggest that the lower CPM concentration in plasma in OS condition does not induce an inferior pharmacological effect. PMID:22022866

  1. Hydrous ferric oxide doped alginate beads for fluoride removal: Adsorption kinetics and equilibrium studies

    NASA Astrophysics Data System (ADS)

    Sujana, M. G.; Mishra, A.; Acharya, B. C.

    2013-04-01

    A new biopolymer beads, composite of hydrous ferric oxide (HFO) and alginate were synthesised, characterised and studied for its fluoride efficiency from water. The beads were characterised by chemical analysis, BET surface area, pHPZC and X-ray diffraction (XRD) analysis. The optimum conditions for fluoride removal were determined by studying operational variables viz. pH, contact time, initial F- concentration, bead dose and temperature. Presence of other anions like SO42-, PO43-, NO3-, Cl- and HCO3- effect on fluoride removal efficiency of prepared beads was also tested. The beads were 0.8-0.9 mm in size and contain 32-33% Fe (III) and showed specific surface area of 25.80 m2 g-1 and pHPZC of 5.15. Modified beads demonstrated Langmuir F- adsorption capacity of 8.90 mg g-1 at pH 7.0. The adsorption kinetics were best described by the pseudo-second order kinetic model followed by intra-particle diffusion as the rate determining step. It was found that about 80% of the adsorbed fluoride could be desorbed by using 0.05 M HCl. The FTIR, Raman and SEM-EDAX analysis were used to study the fluoride adsorption mechanisms on beads. Studies were also conducted to test the potential application of beads for F- removal from drinking water and the treated water quality.

  2. Estimation of equilibrium surface precipitation constants for trivalent metal sorption onto hydrous ferric oxide and calcite

    NASA Astrophysics Data System (ADS)

    Ragavan, Anpalaki J.; Adams, Dean V.

    2009-06-01

    Equilibrium constants for modeling surface precipitation of trivalent metal cations ( M) onto hydrous ferric oxide and calcite were estimated from linear correlations of standard state Gibbs free energies of formation, ( ?Gf,MvX(ss)0) of the surface precipitates. The surface precipitation reactions were derived from Farley et. al. [K.J. Farley, D.A. Dzombak, F.M.M. Morel, J. Colloid Interface Sci. 106 (1985) 226] surface precipitation model, which are based on surface complexation model coupled with solid solution representation for surface precipitation on the solid surface. The ?Gf,MvX(ss)0 values were correlated through the following linear free energy relations ?Gf,M(OH)3(ss)0-791.70r=0.1587?Gn,M0-1273.07 and ?Gf,M2(CO3)3(ss)0-197.241r=0.278?Gn,M0-1431.27 where 'ss' stands for the end-member solid component of surface precipitate, ?Gf,MvX(ss)0 is in kJ/mol, r is the Shannon-Prewitt radius of M in a given coordination state (nm), and ?Gn,M0 is the non-solvation contribution to the Gibbs free energy of formation of the aqueous M ion. Results indicate that the above surface precipitation correlations are useful tools where experimental data are not available.

  3. Adsorption of arsenic onto hydrous ferric oxide: effects of adsorbate\\/adsorbent ratios and co-occurring solutes

    Microsoft Academic Search

    Jennifer A Wilkie; Janet G Hering

    1996-01-01

    The adsorption of arsenic onto hydrous ferric oxide (HFO) was examined for both As(III) and As(V). The effects of adsorbate\\/adsorbent ratios and of the presence of sulfate and calcium as co-occurring solutes were examined. The observed results were compared with the results of calculations obtained using the generalized two-layer model (a surface complexation model in which the coulombic term is

  4. Ferrous iron oxidation under acidic conditions - The effect of ferric oxide surfaces

    NASA Astrophysics Data System (ADS)

    Jones, Adele M.; Griffin, Phillipa J.; Collins, Richard N.; Waite, T. David

    2014-11-01

    In this study, the kinetics of Fe(II) oxidation in the presence of the iron oxyhydroxides ferrihydrite, Si-ferrihydrite, schwertmannite, lepidocrocite and goethite are investigated over the pH range 4-5.5. Despite limited sorption of Fe(II), the rate of Fe(II) oxidation is up to 70-fold faster than in the absence of any Fe oxyhydroxide phase over pH 4.5-5.5. Enhanced Fe(II) oxidation was minor or negligible at pH 4 with undetectable amounts of Fe(II) adsorbed to the iron oxyhydroxides at this pH. Heterogeneous rate constants derived from kinetic modeling were normalized to the concentration of adsorbed Fe(II) and deviated by no more than 13.8% at pH 4.5, 5 and 5.5, indicating that oxidation is proportional to the concentration of adsorbed Fe(II). Average rate constants were found to be: 2.12 ± 0.20, 1.30 ± 0.09, 1.69 ± 0.22, 1.20 ± 0.08 and 0.68 ± 0.09 M-1 s-1 for ferrihydrite, goethite, lepidocrocite, schwertmannite and Si-ferrihydrite, respectively. The role of reactive oxygen species, such as hydrogen peroxide, the hydroxyl radical and superoxide, towards the overall oxidation of Fe(II) was examined but found to have only a minor impact on Fe(II) oxidation when compared to the effect of heterogeneous oxidation.

  5. EXAFS Analyses of Innersphere Surface Complexations of Arsenate and Silicate on Natural Hydrous Ferric Oxides

    NASA Astrophysics Data System (ADS)

    Tommaseo, C. E.; Kersten, M.

    2002-12-01

    X-ray absorption spectroscopy (EXAFS) was used to determine the near range order of three elements (Fe, As, Si) on the surface of hydrous ferric oxide (HFO) from thermal water scales. Fe K-edge EXAFS analyses of the 2nd shell show a better fit including Si as backscattering neighbor. Validation of the Si-Fe bond was obtained by Si K-edge EXAFS spectra, where the light absorber element is surrounded favourably by much heavier second-shell elements. Least-squares fitting of the second-shell Fourier-filtered EXAFS spectrum in the k-range of 5-11 Å-1 yields in a Si-Fe distance of 3.10-3.13Å, and a Si-Si distance of 3.00Å. Both these interatomic distances and the coordination number N = 2 obtained for the Si-Fe shell are consistent with the formation of a corner-bridging bidentate binuclear (2C) surface complex on the HFO surface. The Si-Si bonds and existance of a vibrational band at 964 cm-1 in the infrared spectrum indicate polymerisation of the silicate on the HFO surface (Tommaseo and Kersten). As K-edge XANES analyses showed the As present in form of arsenate scavenged by the HFO phase. As and Si K-edge EXAFS analyses revealed both elements to compete for 2C surface complexation sites. A mean As-Fe distance of 3.03Å indicate an approx. equal distribution of arsenate between 2C (3.24Å) and another 1E (bidentate mononuclear surface complexation) sites (2.84Å). The average Fe-(O,OH) bond length of 2.09Å is compatible with a high proportion of distorted surficial FeIII(O,OH)6 octahedra in the colloidal HFO precipitates of the scale deposits. The slight distortion of the FeIII(O,OH)6 octahedra is consistent with the apparent strong binding of the 1E arsenate surface complexes (Manceau, 1995). The adverse effect of silicate would therefore be overpredicted without surface complexation models constructed to account for both surface functional groups. The Si K-edge EXAFS data provide also a basis for explaining at the molecular level the poisoning of HFO particle growth and the slowing down of the transformation of HFO to crystalline goethite. The inhibition of crystal growth by both oxoanions form a kind of passivation layer which protects HFO from recrystallization and concomitant release of part of the arsenic upon otherwise rapid ageing in the thermal waters. LITERATURE Manceau, A., The mechanism of anion adsorption on iron oxides: Evidence for the bonding of arsenate tetrahedral on free Fe(O,OH)6 edges. Geochim. Cosmochim Acta, Vol. 59, No 17, 3647-3653 (1995). Tommaseo, C.E. and Kersten, M., EXAFS analysis of competitive adsorption of arsenate and silicate on natural hydrous ferric oxides in thermal water scales. Environ. Sci. Technol. (submitted).

  6. Rare earth element partitioning between hydrous ferric oxides and acid mine water during iron oxidation

    USGS Publications Warehouse

    Verplanck, P.L.; Nordstrom, D.K.; Taylor, H.E.; Kimball, B.A.

    2004-01-01

    Ferrous iron rapidly oxidizes to Fe (III) and precipitates as hydrous Fe (III) oxides in acid mine waters. This study examines the effect of Fe precipitation on the rare earth element (REE) geochemistry of acid mine waters to determine the pH range over which REEs behave conservatively and the range over which attenuation and fractionation occur. Two field studies were designed to investigate REE attenuation during Fe oxidation in acidic, alpine surface waters. To complement these field studies, a suite of six acid mine waters with a pH range from 1.6 to 6.1 were collected and allowed to oxidize in the laboratory at ambient conditions to determine the partitioning of REEs during Fe oxidation and precipitation. Results from field experiments document that even with substantial Fe oxidation, the REEs remain dissolved in acid, sulfate waters with pH below 5.1. Between pH 5.1 and 6.6 the REEs partitioned to the solid phases in the water column, and heavy REEs were preferentially removed compared to light REEs. Laboratory experiments corroborated field data with the most solid-phase partitioning occurring in the waters with the highest pH. ?? 2004 Elsevier Ltd. All rights reserved.

  7. Removal of arsenate with hydrous ferric oxide coprecipitation: effect of humic acid.

    PubMed

    Du, Jingjing; Jing, Chuanyong; Duan, Jinming; Zhang, Yongli; Hu, Shan

    2014-02-01

    Insights from the adverse effect of humic acid (HA) on arsenate removal with hydrous ferric oxide (HFO) coprecipitation can further our understanding of the fate of As(V) in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As(V) on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering (SERS), extended X-ray absorption fine structure (EXAFS) spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared (ATR-FTIR) measurement, and charge distribution multisite complexation (CD-MUSIC) modeling. The As(V) removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As(V) mass concentration. The SERS analysis excluded the HA-As(V) complex formation. The EXAFS results indicate that As(V) formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26-3.31 angstroms. The in situ ATR-FTIR measurements show that As(V) replaces surface hydroxyl groups and forms innersphere complex. High concentrations of HA may physically block the surface sites and inhibit the As(V) access. The adsorption of As(V) and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As(V) and HA reasonably well. PMID:25076514

  8. The kinetics of the oxidation of pyrite by ferric ions and dissolved oxygen: an electrochemical study

    Microsoft Academic Search

    Paul R. Holmes; Frank K. Crundwell

    2000-01-01

    The dissolution of pyrite is important in the geochemical cycling of iron and sulphur, in the formation of acid mine drainage, and in the extraction of metals by bacterial leaching. Many researchers have studied the kinetics of dissolution, and the rate of dissolution has often been found to be half-order in ferric ions or oxygen. Previous work has not adequately

  9. Mafic Silicate and Ferric Oxide Mineralogy of Gale Crater and the Mars Science Laboratory Rover Field Site

    NASA Astrophysics Data System (ADS)

    Bell, J. F.; Anderson, R. B.; Milliken, R.; Hamilton, V. E.; Edgett, K. S.

    2011-12-01

    Gale, a 155 km diameter impact crater on the boundary of the Martian southern highlands near 5S, 222W, has been selected as the field site for NASA's Mars Science Laboratory (MSL) rover, Curiosity. Several published studies have focused on the discovery, mapping, and analysis of hydrated or hydroxylated minerals (e.g., sulfates, phyllosilicates) in Gale as exciting potential targets for in situ exploration. Less attention has generally been paid to the anhydrous mafic (ferrous) silicates and ferric oxides which have also been detected in Gale from orbital remote sensing studies and which may be the precursor parent materials that weathered into the observed aqueous phases. Here we review previous and new observations regarding the presence and spatial distribution of anhydrous ferrous silicates and ferric oxides in Gale and discuss the scientific implications for the close-up study of these materials with the MSL payload. Despite a common misconception that Gale is a "dusty" site, visible to near-IR observations from the Mars Express OMEGA and Mars Reconnaissance Orbiter CRISM and thermal infrared observations from Mars Global Surveyor TES and Mars Odyssey THEMIS provide evidence for olivine and pyroxene and the anhydrous ferric oxide, hematite, associated with distinct geologic materials in Gale. Olivine-bearing mafic (likely basaltic) materials have been interpreted to occur in low albedo aeolian dunes near and around the base of the 5 km high mound of sedimentary rock in the crater. Both low and high calcium pyroxene (LCP, HCP) have been identified in and around the crater, with CRISM data showing HCP-bearing material occurring primarily within a "cap rock" on the relatively flat crater floor and within the relatively dust-free units of the lower few km of the sedimentary rock mound. Potentially more mobile (via wind) LCP-bearing material occurs throughout the crater and the lower few km of the mound and into the low albedo wind streak that extends ~200 km to the south. Models of TES spectral data are consistent with the presence of LCP+HCP, high silica phases, feldspar, olivine, and possibly sulfate in the low albedo surfaces exposed in the crater, central mound, and southern wind streak. VNIR data reveal that a ferric oxide phase, potentially fine-grained (red) hematite, occurs in association with both HCP and LCP units in a so-called "mound skirting unit" within the Curiosity field site. THEMIS and CRISM imaging both display compositional layering within mound materials that will be accessible to the rover.

  10. Visible Wavelength Spectroscopy of Ferric Minerals: A Key Tool for Identification of Ancient Martian Aqueous Environments

    NASA Technical Reports Server (NTRS)

    Murchie, Scott L.; Bell, J. F., III; Morris, Richard V.

    2000-01-01

    The mineralogic signatures of past aqueous alteration of a basaltic Martian crust may include iron oxides and oxyhydroxides, zeolites, carbonates, phyllosilicates, and silica. The identities, relative abundances, and crystallinities of the phases formed in a particular environment depend on physicochemical conditions. At one extreme, hot spring environments may be characterized by smectite-chlorite to talc-kaolinite silicate assemblages, plus crystalline ferric oxides dominated by hematite. However, most environments, including cold springs, pedogenic layers, and ponded surface water, are expected to deposit iron oxides and oxyhydroxides, carbonates, and smectite-dominated phyllosilicates. A substantial fraction of the ferric iron is expected to occur in nanophase form, with the exact mineralogy strongly influenced by Eh-pH conditions. Detection of these phases has been an objective of a large body of terrestrial telescopic, Mars orbital, and landed spectral investigations and in situ compositional measurements. However, clear identifications of many of these phases is lacking. Neither carbonate nor silica has been unequivocally detected by any method. Although phyllosilicates may occur near the limit of detection by remote sensing, in general they appear to occur in only poorly crystalline form. In contrast, compelling evidence for ferric iron minerals has been gathered by recent telescopic investigations, the Imager for Mars Pathfinder (IMP), and the Thermal Emission Spectrometer (TES) on the Mars Global Surveyor (MGS). These data yield two crucial findings: (1) In the global, high spatial resolution TES data set, highly crystalline ferric iron (as coarse-grained 'gray' hematite) has been recognized but with only very limited spatial occurrence and (2) Low-resolution telescopic reflectance spectroscopy, very limited orbital reflectance spectroscopy, and landed multispectral imaging provide strong indications that at least two broad classes of ferric iron minerals are commonplace in non-dust covered regions.

  11. Fayalite Oxidation Processes: Experimental Evidence for the Stability of Pure Ferric Fayalite?

    NASA Technical Reports Server (NTRS)

    Martin, A. M.; Righter, K.; Keller, L. P.; Medard, E.; Devouard, B.; Rahman, Z.

    2011-01-01

    Olivine is one of the most important minerals in Earth and planetary sciences. Fayalite Fe2(2+)SiO4, the ferrous end-member of olivine, is present in some terrestrial rocks and primitive meteorites (CV3 chondrites). A ferric fayalite (or ferri-fayalite), Fe(2+) Fe2(3+)(SiO4)2 laihunite, has been reported in Earth samples (magnetite ore, metamorphic and volcanic rocks...) and in Martian meteorites (nakhlites). Laihunite was also synthesized at 1 atmosphere between 400 and 700 C. We show evidence for the stability of a pure ferrifayalite end-member and for potential minerals with XFe(3+) between 2/3 and 1.

  12. Detecting Adsorbed Sulfate and Phosphate on Nanophase Weathering Products on Mars

    NASA Astrophysics Data System (ADS)

    Rampe, E. B.; Morris, R. V.

    2012-12-01

    Characterizing the mineralogy and chemistry of aqueous alteration phases on the martian surface is essential for understanding past aqueous processes because the types of secondary phases present and their chemical compositions tell us about the environments in which they formed. Orbital mid-infrared data and in-situ mineralogical and chemical data from the martian surface indicate that Si/Al- and Fe-bearing nanophase weathering products are widespread, including allophane and nanophase ferric oxide (npOx), which includes any combination of superparamagnetic hematite and goethite, ferrihydrite, schwertmannite, akaganeite, iddingsite, and palagonite (altered basaltic glass) [Morris et al., 2006; Michalski et al., 2006; Rampe et al., in press]. These weathering products have larger surface areas and variable surface charge and can adsorb anions and cations onto their surfaces. Some anions, such as sulfate and phosphate, specifically chemically adsorb onto mineral/mineraloid surfaces so that these complexes are covalently bonded and form ligands. Nanophase weathering products on Earth can specifically adsorb up to a few weight percent to a few tens of weight percent phosphate and sulfate, respectively [Parfitt and Smart, 1978; Jara et al., 2006]. Phosphate and sulfate have been identified in martian rocks and soils in abundances of up to ~5 wt.% and ~30 wt.%, respectively [Gellert et al., 2006; Ming et al., 2006], and it has been suggested that phosphate and sulfate ions may be adsorbed on nanophase weathering products on the martian surface [Greenwood and Blake, 2006; Morris et al., 2006]. What is relatively unknown is how to use in-situ and orbital instruments on Mars to determine if these ions are present as discrete minerals or adsorbed onto the surfaces of weathering products. We adsorbed phosphate and sulfate onto allophane surfaces in the laboratory. Here, we present laboratory measurements of phosphate- and sulfate-adsorbed allophane to compare to in-situ observations from CheMin and SAM on Mars Science Laboratory and remote observations from OMEGA, CRISM, and TES. CheMin- and OMEGA/CRISM-relevant laboratory measurements reveal minor differences between ion-free and ion-adsorbed allophane that would not be detectable by those instruments. However, SAM-relevant evolved gas analyses of sulfate-adsorbed allophane show a high-temperature (>950 C) release related to SO2 gas. The release at high temperatures suggests that sulfate was strongly bonded to the allophane surface. TES-relevant thermal-infrared emission spectra of phosphate- and sulfate-adsorbed allophane display broad absorptions near 1000 cm-1 from P-O and S-O vibrations. Our laboratory measurements suggest that ions adsorbed onto weathering product surfaces may be recognized on Mars with in-situ measurements by SAM on MSL and with orbital measurements from TES. Future experiments will include similar laboratory measurements of phosphate- and sulfate-adsorbed nanophase ferric oxides.

  13. Ferric Oxide Mediated Formation of PCDD/Fs from 2-Monochlorophenol

    PubMed Central

    Nganai, Shadrack; Lomnicki, Slawo; Dellinger, Barry

    2012-01-01

    The copper oxide, surface-mediated formation of polychlorinated dibenzop-dioxins and dibenzofurans (PCDD/F) from precursors such as chlorinated phenols is considered to be a major source of PCDD/F emissions from combustion sources. In spite of being present at 2–50x higher concentrations than copper oxide, virtually no studies of the iron oxide-mediated formation of PCDD/F have been reported in the literature. We have performed packed bed, flow reactor studies of the reaction of 50 ppm gas phase 2-monochlorophenol (2-MCP) over a surface of 5% iron oxide on silica over a temperature range of 200–500 °C. Dibenzo-p-dioxin (DD), 1-monochlorodibenzo-p-dioxin (1-MCDD), 4,6-dichlorodibenzofuran (4,6-DCDF), and dibenzofuran (DF) were formed in maximum yields of 0.1, 0.2, 0.3, and 0.4 %, respectively. The yield of PCDD/F over iron oxide peaked at temperatures 50–100 °C higher in temperature than over copper oxide. The maximum yields of DD, 1-MCDD and 4,6-DCDF were 2x and 5x higher over iron oxide, respectively, than over copper oxide, while DF was not observed at all for copper oxide. The resulting PCDD/PCDF ratio was 0.39 versus 1.2 observed for iron oxide and copper oxide, respectively, which is in agreement with PCDD to PCDF ratios in full-scale combustors that are typically ?1. The combination of 2–50x higher concentrations of iron oxide than copper oxide in most full-scale combustors and 2.5x higher yields of PCDD/F observed in the laboratory, suggest that iron oxide may contribute as much as 5–125x more than copper oxide to the emissions of PCDD/F from full-scale combustors. PMID:19238966

  14. Biodiesel synthesis catalyzed by transition metal oxides: ferric-manganese doped tungstated/molybdena nanoparticle catalyst.

    PubMed

    Alhassan, Fatah Hamid; Rashid, Umer; Taufiq-Yap, Yun Hin

    2015-01-01

    The solid acid Ferric-manganese doped tungstated/molybdena nananoparticle catalyst was prepared via impregnation reaction followed by calcination at 600°C for 3 h. The characterization was done using X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis (TGA), temperature programmed desorption of NH3 (TPD-NH3), X-ray fluorescence (XRF), Transmission electron microscope (TEM) and Brunner-Emmett-Teller surface area measurement (BET). Moreover, dependence of biodiesel yield on the reaction variables such as the reaction temperature, catalyst loading, as well as molar ratio of methanol/oil and reusability were also appraised. The catalyst was reused six times without any loss in activity with maximum yield of 92.3% ±1.12 achieved in the optimized conditions of reaction temperature of 200°C; stirring speed of 600 rpm, 1:25 molar ratio of oil to alcohol, 6 % w/w catalyst loading as well as 8 h as time of the reaction. The fuel properties of WCOME's were evaluated, including the density, kinematic viscosity, pour point, cloud point and flash point whereas all properties were compared with the limits in the ASTM D6751 standard. PMID:25492234

  15. Characterization of Nanophase Materials

    NASA Astrophysics Data System (ADS)

    Wang, Zhong Lin

    2000-01-01

    Engineering of nanophase materials and devices is of vital interest in electronics, semiconductors and optics, catalysis, ceramics and magnetism. Research associated with nanoparticles has widely spread and diffused into every field of scientific research, forming a trend of nanocrystal engineered materials. The unique properties of nanophase materials are entirely determined by their atomic scale structures, particularly the structures of interfaces and surfaces. Development of nanotechnology involves several steps, of which characterization of nanoparticles is indespensable to understand the behavior and properties of nanoparticles, aiming at implementing nanotechnolgy, controlling their behavior and designing new nanomaterials systems with super performance. The book will focus on structural and property characterization of nanocrystals and their assemblies, with an emphasis on basic physical approach, detailed techniques, data interpretation and applications. Intended readers of this comprehensive reference work are advanced graduate students and researchers in the field, who are specialized in materials chemistry, materials physics and materials science.

  16. Amperometric determination of acetylcholine-A neurotransmitter, by chitosan/gold-coated ferric oxide nanoparticles modified gold electrode.

    PubMed

    Chauhan, Nidhi; Pundir, C S

    2014-11-15

    An amperometric acetylcholine biosensor was constructed by co-immobilizing covalently, a mixture of acetylcholinesterase (AChE) and choline oxidase (ChO) onto nanocomposite of chitosan (CHIT)/gold-coated ferric oxide nanoparticles (Fe@AuNPs) electrodeposited onto surface of a Au electrode and using it as a working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode connected through potentiostat. The biosensor is based on electrochemical measurement of H2O2 generated from oxidation of choline by immobilized ChO, which in turn is produced from hydrolysis of acetylcholine by immobilized AChE. The biosensor exhibited optimum response within 3s at +0.2V, pH 7.0 and 30°C. The enzyme electrode had a linear working range of 0.005-400 µM, with a detection limit of 0.005 µM for acetylcholine. The biosensor measured plasma acetylcholine in apparently healthy and persons suffering from Alzheimer's disease. The enzyme electrode was unaffected by a number of serum substances but lost 50% of its initial activity after its 100 uses over a period of 3 months, when stored at 4°C. PMID:24836212

  17. Influence of Electron Donor\\/Acceptor Concentrations on Hydrous Ferric Oxide (HFO) Bioreduction

    Microsoft Academic Search

    James K. Fredrickson; Sreenivas Kota; Ravi K. Kukkadapu; Chongxuan Liu; John M. Zachara

    2003-01-01

    Dissimilatory metal-reducing bacteria (DMRB) facilitate the reduction of Feand Mn oxides in anoxic soils and sediments and play an important role inthe cycling of these metals and other elements such as carbon in aqueousenvironments. Previous studies investigating the reduction of Fe(III) oxidesby DMRB focused on reactions under constant initial electron donor (lactate)and electron acceptor (Fe oxide) concentrations. Because the concentrationsof

  18. Ferric sulfates on Mars

    NASA Astrophysics Data System (ADS)

    Burns, Roger G.

    Evidence is presented for the possible formation and existence of ferric sulfato complexes and hydroxo ferric sulfate minerals in the permafrost on Mars. Acidic groundwater, derived from atmospheric oxidation of volcanogenic H2S to H2SO4 aerosols, promoted chemical weathering of fayalitic olivines, iron-rich pyroxenes, plagioclase feldspar, and pyrrhotite-pentlandite mineral assemblages in crustal ultramafic and basic igneous rocks. The acidic groundwater entered into electrochemical reactions with the iron sulfides, yielding dissolved FeSO4+, Fe(SO4)2-, and FeOH2+ complex ions, and the precipitation of basic ferric sulfate minerals such as those belonging to the roemerite, copiapite, botryogen, and jarosite-alunite groups. These phases are stabilized at low temperatures and pH in Martian permafrost. The occurrence of jarosites in terrestrial arid regions suggests that they could also survive on the surface of Mars. Melting of the permafrost and raising of the pH may have initiated the hydrolysis of dissolved ferric sulfato complex ions and led to the precipitation of FeOOH, which reacted with precipitated silica to form phyllosilicates. Alternatively, degradation of the hydrolysate FeOOH to Fe2O3 during sublimation of permafrost exposed on Mars' surface may account for the presence of eolian maghemite suspected to be the magnetic mineral observed on the Viking Landers.

  19. Ferric sulfates on Mars

    NASA Astrophysics Data System (ADS)

    Burns, Roger G.

    1987-09-01

    Evidence is presented for the possible formation and existence of ferric sulfato complexes and hydroxo ferric sulfate minerals in the permafrost on Mars. Acidic ground water, derived from atmospheric oxidation of volcanogenic H2S to H2SO4 aerosols, promoted chemical weathering of fyalitic olivines, iron-rich pyroxenes, plagioclase feldspar, and pyrrhotite-pentlandite mineral assemblages in crustal ultramafic and basic igneous rocks. The acidic groundwater entered into electrochemical reactions with the iron sulfides, yielding dissolved FeSO4+, Fe(SO4)2-, and FeOH2+ complex ions, and the precipitation of basic ferric sulfate minerals such as those belonging to the roemerite, copiapite, botryogen, and jarosite-alunite groups. These phases are stabilized at low temperatures and pH in Martian permafrost. The occurrence of jarosites in terrestrial arid regions suggests that they could also survive on the surface of mars. Melting of the permafrost and raising of the pH may have initiated the hydrolysis of dissolved ferric sulfato complex ions and led to the precipitation of FeOOH, which reacted with precipitated silica to form phyllosilicates. Alternatively, degradation of the hydrolysate FeOOH to Fe2O3 during sublimation of permafrost exposed on Mars' surface may account for the presence of eolian maghemite suspected to be the magnetic mineral observed on the Viking Landers.

  20. A comparative study on surface morphological investigations of ferric oxide for LPG and opto-electronic humidity sensors

    NASA Astrophysics Data System (ADS)

    Singh, Satyendra; Verma, Nidhi; Yadav, B. C.; Prakash, Rajiv

    2012-09-01

    In the present work nanostructured ferric oxides were synthesized via hydroxide precipitation method without using any surfactant and size selection medium. The surface morphologies and structure of samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The structural analysis confirmed the formation of Fe2O3 with ?-phase and rhombohedral structure. Optical and thermal properties were investigated by using UV-visible absorption spectroscopy and differential scanning calorimetry (DSC) techniques. Pelletizations of materials were done using hydraulic press and these pellets were investigated with the exposition of liquefied petroleum gas. Variations in resistance of the pellet with time for different concentrations of LPG were recorded at room temperature (27 °C). The maximum value of average sensitivity was found ˜5 for 5 vol.% of LPG. Our results show that the LPG sensing behavior was inspired by the different kinds of surface morphologies of Fe2O3 and inferred that the spherical porous nanoparticles synthesized via hydroxide precipitation process (S-3) had best response to LPG.

  1. Effects of pH, floc age and organic compounds on the removal of phosphate by pre-polymerized hydrous ferric oxides

    Microsoft Academic Search

    Yanpeng Mao; A. Ninh Pham; Yongjia Xin; T. David Waite

    The extent of adsorption of phosphate onto pre-polymerized hydrous ferric oxides (HFO) is strongly dependent upon pH, HFO age and concentration of competing anions with the phosphate adsorption capacity decreasing significantly with increase in pH, HFO age and concentration of competing anion. A semi-empirical diffuse layer model and a molecular model (the CD-MUSIC model), which take these factors into account,

  2. Study of ferric oxide nanoparticles-tris-(2,4-di-t-amylphenoxy)-(8-quinolinolyl) copper phthalocyanine composite LB film

    Microsoft Academic Search

    Lihua Huo; Lixin Cao; Xinglin Li; Wei Li; Haining Cui; Dapeng Jiang; Guangfu Zeng; Shiquan Xi

    2000-01-01

    The ferric oxide nanoparticles-tris-(2,4-di-t-amylphenoxy)-(8-quinolinolyl) copper phthalocyanine (CuPcA2) composite ultrathin film was obtained by LB (Langmuir–Blodgett) technique. Structure of the composite LB film was characterized by X-ray photoelectron spectra, transmission electron microscopy, infrared spectra and visible spectra. Gas sensitivity measurements indicate that the composite LB film is sensitive to 100–200 ppm C2H5OH at room temperature.

  3. Adsorption Studies with Arsenic onto Ferric Hydroxide Gel in a Non-oxidizing Environment: the Effect of Co-occurring Solutes and Speciation

    Microsoft Academic Search

    Bishwajit Nayak; Mrinal Kumar Sengupta; Saad Ahamed; Arup Pal; Amitava Mukherjee

    2006-01-01

    Groundwater arsenic contamination has emerged as a major health threat to millions of people around the world. Studying the sorption process of As(III) and As(V) onto ferric hydroxide gel is important to understand the mobilization of arsenic under non- oxidizing conditions. Most of the previous adsorption studies were limited to single element or multi-element equilibrium in syn- thetic water. To

  4. Ion exchangers in radioactive waste management. Part XI. Removal of barium and strontium ions from aqueous solutions by hydrous ferric oxide.

    PubMed

    Mishra, S P; Tiwary, D

    1999-10-01

    The uptake of Ba(II) and Sr(II) by hydrous ferric oxide (HFO) was studied as a function of contact time, concentration, temperature and pH of the respective adsorptive solutions employing the 'radiotracer technique'. The uptake of both the ions was found to increase with the increase in concentration, temperature and pH of the adsorptive solutions. Concentration dependence data fitted well to the Freundlich adsorption isotherm over the entire range of concentration (10(-2)-10(-7) M) and the uptake process followed first-order rate kinetics. The desorption experiments demonstrate the irreversible nature of the uptake process, however, in the presence of H+ ions, i.e. on acidification, an appreciable amount of metal ions were removed in the bulk solution. The radiation stability of hydrous ferric oxide towards the uptake of Ba(II) and Sr(II) was also examined by using samples of hydrous ferric oxide irradiated by neutrons and gamma-rays prior to be employing as sorbents. The presence of some mono- and divalent co-ions along with the studied ions suppressed their removal appreciably. PMID:10464913

  5. Application of citrate-stabilized gold-coated ferric oxide composite nanoparticles for biological separations

    NASA Astrophysics Data System (ADS)

    Hien Pham, Thao Thi; Cao, Cuong; Sim, Sang Jun

    Gold-coated magnetic nanoparticles were synthesized with size ranging from 15 to 40 nm using sodium citrates as the reducing agent. Oxidized magnetites (Fe 3O 4) fabricated by co-precipitation of Fe 2+ and Fe 3+ in strong alkaline solution were used as magnetic cores. The structures of gold (Au) shell and magnetic core (Au-Fe) were studied by transmission electron microscopy (TEM) image and energy dispersive spectroscopy (EDS) spectrum. Results from high-resolution X-ray diffraction (HR XRD) show that the Au-Fe oxide nanoparticles have a face-centered cubic shape with the crystalline faces of {1 1 1}. The Au-coated magnetic nanoparticles exhibited a surface plasmon resonance peak at 528 nm. The nanoparticles are well dispersed in distilled water. A 3000 G permanent magnet was successfully used for the separation of the functionalized nanoparticles. Magnetic properties of the nanoparticles were determined by magnetic force microscope (MFM) in nanometric resolution and vibrating sample magnetometer (VSM). Magnetic separation of biological molecules using Au-coated magnetic oxide composite nanoparticles was examined after attachment of protein immunoglobulin G (IgG) through electrostatic interactions. Using this method, separation was achieved with a maximum yield of 35% at an IgG concentration of 400 ng/ml.

  6. The Formation, Structure, and Ageing of As-Rich Hydrous Ferric Oxide at the Abandoned Sb Deposit Pezinok (Slovakia)

    SciTech Connect

    Majzlan,J.; Lalinska, B.; Chovan, M.; Jurkovic, L.; Milovska, S.; Gottlicher, J.

    2007-01-01

    The abandoned Sb deposit Pezinok in Slovakia is a significant source of As and Sb pollution that can be traced in the upper horizons of soils kilometers downstream. The source of the metalloids are two tailing impoundments which hold {approx}380,000 m{sup 3} of mining waste. The tailings and the discharged water have circumneutral pH values (7.0 {+-} 0.6) because the acidity generated by the decomposition of the primary sulfides (pyrite, FeS{sub 2}; arsenopyrite, FeAsS; berthierite, FeSb{sub 2}S{sub 4}) is rapidly neutralized by the abundant carbonates. The weathering rims on the primary sulfides are iron oxides which act as very efficient scavengers of As and Sb (with up to 19.2 wt% As and 23.7 wt% Sb). In-situ {mu}-XANES experiments indicate that As in the weathering rims is fully oxidized (As{sup 5+}). The pore solutions in the impoundment body contain up to 81 ppm As and 2.5 ppm Sb. Once these solutions are discharged from the impoundments, they precipitate or deposit masses of As-rich hydrous ferric oxide (As-HFO) with up to 28.3 wt% As{sub 2}O{sub 5} and 2.7 wt% Sb. All As-HFO samples are amorphous to X-rays. They contain Fe and As in their highest oxidation state and in octahedral and tetrahedral coordination, respectively, as suggested by XANES and EXAFS studies on Fe K and As K edges. The iron octahedra in the As-HFO share edges to form short single chains and the chains polymerize by sharing edges or corners with the adjacent units. The arsenate ions attach to the chains in a bidentate-binuclear and monodentate fashion. In addition, hydrogen-bonded complexes may exist to satisfy the bonding requirements of all oxygen atoms in the first coordination sphere of As{sup 5+}. Structural changes in the As-HFO samples were traced by chemical analyses and Fe EXAFS spectroscopy during an ageing experiment. As the samples age, As becomes more easily leachable. EXAFS spectra show a discernible trend of increasing number of Fe-Fe pairs at a distance of 3.3-3.5 {angstrom}, that is, increasing polymerization of the iron octahedra to form larger units with fewer adsorption sites. Therefore, although ferrihydrite is an excellent material for capturing arsenic, its use as a medium for a long-term storage of As has to be considered with a great caution because it will tend to release arsenic as it ages.

  7. Development of polymer-based nanosized hydrated ferric oxides (HFOs) for enhanced phosphate removal from waste effluents.

    PubMed

    Pan, Bingjun; Wu, Jun; Pan, Bingcai; Lv, Lu; Zhang, Weiming; Xiao, Lili; Wang, Xiaoshu; Tao, Xiancong; Zheng, Shourong

    2009-09-01

    Phosphate originated from industrial effluents is one of the key factors responsible for eutrophication of the receiving waterways especially in the developing countries such as China. In the current study we proposed a novel process to immobilize nanoparticulate hydrated ferric oxide (HFO) within a macroporous anion exchange resin D-201, and obtained a hybrid adsorbent (HFO-201) for enhanced phosphate removal from aqueous system. The resulting HFO-201 possesses two types of adsorption sites for phosphate removal, the ammonium groups bound to the D-201 matrix and the loaded HFO nanoparticles. The coexisting sulfate anion strongly competes for ammonium groups, which bind phosphate through electrostatic interaction. However, it does not pose any noticeable effect on phosphate adsorption by the loaded HFO nanoparticles, which is driven by the formation of the inner-sphere complexes. Batch adsorption experiments also indicated that HFO-201 exhibits a little higher capacity for phosphate than the commercially available phosphate-specific adsorbent ArsenX(np), which possesses similar structure of HFO-201 and is produced by another patented technique. Fixed-bed column tests indicate that phosphate retention by HFO-201 from the synthetic waters results in the significant decrease of P from 2mg/L to less than 0.01 mg/L, with the treatment capacity of approximately 700 bed volume (BV) per run, while that for D-201 was less than 200 BV under otherwise identical conditions. Such satisfactory performance of the hybrid adsorbent is mainly attributed to the specific affinity of HFO toward phosphate as well as the Donnan membrane effect exerted by the anion exchanger support D-201. Moreover, the exhausted HFO-201 was amenable to efficient in situ regeneration with a binary NaOH-NaCl solution for repeated use without any significant capacity loss. Similar satisfactory results were also observed by using a phosphate-containing industrial effluent as the feeding solution. PMID:19615711

  8. Osteoblast adhesion on nanophase ceramics

    Microsoft Academic Search

    Thomas J Webster; Richard W Siegel; Rena Bizios

    1999-01-01

    Osteoblast adhesion on nanophase alumina (Al2O3) and titania (TiO2) was investigated in vitro. Osteoblast adhesion to nanophase alumina and titania in the absence of serum from Dulbecco’s modified Eagle medium (DMEM) was significantly (P<0.01) less than osteoblast adhesion to alumina and titania in the presence of serum. In the presence of 10% fetal bovine serum in DMEM osteoblast adhesion on

  9. High-energy mechanical synthesis of nanophase fluorite-structured mixed oxide catalysts with a high redox activity

    SciTech Connect

    Primavera, A.; Trovarelli, A.; Terribile, D.; Leitenburg, C. de; Dolcetti, G. [Univ. di Udine (Italy). Dipt. di Scienze e Tecnologie Chimiche; Llorca, J. [Univ. de Barcelona (Spain). Dept. de Quimica Inorganica

    1997-12-31

    A series of nanostructured, highly defective, ternary solid solutions containing CeO{sub 2}, ZrO{sub 2}, and MnO{sub 2} or CuO were prepared by high-energy mechanical milling of individual components. Morphological and redox properties were studied by XRD, HRTEM and temperature-programmed reduction techniques. It was shown that the introduction of small amounts of copper and manganese strongly promotes the redox behavior of cerium at lower temperatures in comparison with CeO{sub 2} and CeO{sub 2}-ZrO{sub 2}. High temperature treatment of up to 1,400 K was also shown to further promote overall redox capacity without affecting low-temperature redox behavior. Moreover, evidence is provided to show that Cu and Mn are dissolved within the CeO{sub 2} lattice structure. Addition of dopants enhances catalytic redox properties in the oxidation of CO at low temperatures, which is associated with the high concentration of oxygen vacancies that form on the introduction of aliovalent elements into the ceria-zirconia lattice.

  10. Nuclear fuel elements made from nanophase materials

    DOEpatents

    Heubeck, Norman B. (Schenectady, NY)

    1998-01-01

    A nuclear reactor core fuel element is composed of nanophase high temperature materials. An array of the fuel elements in rod form are joined in an open geometry fuel cell that preferably also uses such nanophase materials for the cell structures. The particular high temperature nanophase fuel element material must have the appropriate mechanical characteristics to avoid strain related failure even at high temperatures, in the order of about 3000.degree. F. Preferably, the reactor type is a pressurized or boiling water reactor and the nanophase material is a high temperature ceramic or ceramic composite. Nanophase metals, or nanophase metals with nanophase ceramics in a composite mixture, also have desirable characteristics, although their temperature capability is not as great as with all-ceramic nanophase material. Combinations of conventional or nanophase metals and conventional or nanophase ceramics can be employed as long as there is at least one nanophase material in the composite. The nuclear reactor so constructed has a number of high strength fuel particles, a nanophase structural material for supporting a fuel rod at high temperature, a configuration to allow passive cooling in the event of a primary cooling system failure, an ability to retain a coolable geometry even at high temperatures, an ability to resist generation of hydrogen gas, and a configuration having good nuclear, corrosion, and mechanical characteristics.

  11. Nuclear fuel elements made from nanophase materials

    DOEpatents

    Heubeck, N.B.

    1998-09-08

    A nuclear reactor core fuel element is composed of nanophase high temperature materials. An array of the fuel elements in rod form are joined in an open geometry fuel cell that preferably also uses such nanophase materials for the cell structures. The particular high temperature nanophase fuel element material must have the appropriate mechanical characteristics to avoid strain related failure even at high temperatures, in the order of about 3000 F. Preferably, the reactor type is a pressurized or boiling water reactor and the nanophase material is a high temperature ceramic or ceramic composite. Nanophase metals, or nanophase metals with nanophase ceramics in a composite mixture, also have desirable characteristics, although their temperature capability is not as great as with all-ceramic nanophase material. Combinations of conventional or nanophase metals and conventional or nanophase ceramics can be employed as long as there is at least one nanophase material in the composite. The nuclear reactor so constructed has a number of high strength fuel particles, a nanophase structural material for supporting a fuel rod at high temperature, a configuration to allow passive cooling in the event of a primary cooling system failure, an ability to retain a coolable geometry even at high temperatures, an ability to resist generation of hydrogen gas, and a configuration having good nuclear, corrosion, and mechanical characteristics. 5 figs.

  12. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...from iron and chlorine or from ferric oxide and hydrogen chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron (III) chloride hexahydrate, FeC13 . 6H2 0, CAS Reg. No. 10025-77-1)...

  13. In situ generated gas bubble-assisted modulation of the morphologies, photocatalytic, and magnetic properties of ferric oxide nanostructures synthesized by thermal decomposition of iron nitrate

    Microsoft Academic Search

    Guoxiu Tong; Jianguo Guan; Zhidong Xiao; Xing Huang; Yao Guan

    2010-01-01

    Ferric oxide (Fe2O3) complex nanoarchitectures with high BET specific surface area, superior photocatalytic activity and modulated magnetic properties\\u000a are facilely synthesized via controlled thermal decomposition of iron(III) nitrate nonahydrate. The products are characterized\\u000a by X-ray diffraction, Fourier-transforming infrared spectra, field-emission scanning electron microscope, field-emission high-resolution\\u000a transmission electron microscope, and nitrogen physisorption and micrometrics analyzer. The corresponding photocatalytic activity\\u000a and static

  14. Chemopreventive effect of Padina boergesenii extracts on ferric nitrilotriacetate (Fe-NTA)-induced oxidative damage in Wistar rats

    Microsoft Academic Search

    Rajamani Karthikeyan; T. Manivasagam; P. Anantharaman; T. Balasubramanian; S. T. Somasundaram

    2011-01-01

    The present study was designed to investigate the prophylactic effect of extracts of the brown alga Padina boergesenii against potent nephrotoxic agent ferric nitrilotriacetate (Fe-NTA), in blood circulation of rats. Administration of Fe-NTA\\u000a for seven consecutive days significantly enhanced lipid peroxidation accompanied with reduction in glutathione content. Together\\u000a with this, the level of antioxidant enzymes, glutathione peroxidase, superoxide dismutase, and

  15. Ferric Carboxymaltose Injection

    MedlinePLUS

    Ferric carboxymaltose injection is used to treat iron-deficiency anemia (a lower than normal number of red blood ... to stop working) who are not on dialysis. Ferric carboxymaltose injection is in a class of medications called ...

  16. The nanophase iron mineral(s) in Mars soil

    NASA Technical Reports Server (NTRS)

    Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.

    1993-01-01

    A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism for, the somewhat puzzling observations of the Viking biology experiments. Their unique chemical reactivities are attributed to the combined catalytic effects of the iron oxide/oxyhydroxides and silicate phase surfaces. The reflectance spectrum of the clay-iron preparations in the visible range is generally similar to the reflectance curves of bright regions on Mars. This strengthens the evidence for the predominance of nanophase iron oxides/oxyhydroxides in Mars soil. The mode of formation of these nanophase iron oxides on Mars is still unknown. It is puzzling that despite the long period of time since aqueous weathering took place on Mars, they have not developed from their transitory stage to well-crystallized end-members. The possibility is suggested that these phases represent a continuously on-going, extremely slow weathering process.

  17. Heterogeneous catalytic ozonation of biologically pretreated Lurgi coal gasification wastewater using sewage sludge based activated carbon supported manganese and ferric oxides as catalysts.

    PubMed

    Zhuang, Haifeng; Han, Hongjun; Hou, Baolin; Jia, Shengyong; Zhao, Qian

    2014-08-01

    Sewage sludge of biological wastewater treatment plant was converted into sewage sludge based activated carbon (SBAC) with ZnCl? as activation agent, which supported manganese and ferric oxides as catalysts (including SBAC) to improve the performance of ozonation of real biologically pretreated Lurgi coal gasification wastewater. The results indicated catalytic ozonation with the prepared catalysts significantly enhanced performance of pollutants removal and the treated wastewater was more biodegradable and less toxic than that in ozonation alone. On the basis of positive effect of higher pH and significant inhibition of radical scavengers in catalytic ozonation, it was deduced that the enhancement of catalytic activity was responsible for generating hydroxyl radicals and the possible reaction pathway was proposed. Moreover, the prepared catalysts showed superior stability and most of toxic and refractory compounds were eliminated at successive catalytic ozonation runs. Thus, the process with economical, efficient and sustainable advantages was beneficial to engineering application. PMID:24907577

  18. Development of Surface Complexation Models of Cr(VI) Adsorption on Soils, Sediments and Model Mixtures of Kaolinite, Montmorillonite, ?-Alumina, Hydrous Manganese and Ferric Oxides and Goethite

    SciTech Connect

    Koretsky, Carla [Western Michigan University] [Western Michigan University

    2013-11-29

    Hexavalent chromium is a highly toxic contaminant that has been introduced into aquifers and shallow sediments and soils via many anthropogenic activities. Hexavalent chromium contamination is a problem or potential problem in the shallow subsurface at several DOE sites, including Hanford, Idaho National Laboratory, Los Alamos National Laboratory and the Oak Ridge Reservation (DOE, 2008). To accurately quantify the fate and transport of hexavalent chromium at DOE and other contaminated sites, robust geochemical models, capable of correctly predicting changes in chromium chemical form resulting from chemical reactions occurring in subsurface environments are needed. One important chemical reaction that may greatly impact the bioavailability and mobility of hexavalent chromium in the subsurface is chemical binding to the surfaces of particulates, termed adsorption or surface complexation. Quantitative thermodynamic surface complexation models have been derived that can correctly calculate hexavalent chromium adsorption on well-characterized materials over ranges in subsurface conditions, such pH and salinity. However, models have not yet been developed for hexavalent chromium adsorption on many important constituents of natural soils and sediments, such as clay minerals. Furthermore, most of the existing thermodynamic models have been developed for relatively simple, single solid systems and have rarely been tested for the complex mixtures of solids present in real sediments and soils. In this study, the adsorption of hexavalent chromium was measured as a function of pH (3-10), salinity (0.001 to 0.1 M NaNO3), and partial pressure of carbon dioxide(0-5%) on a suite of naturally-occurring solids including goethite (FeOOH), hydrous manganese oxide (MnOOH), hydrous ferric oxide (Fe(OH)3), ?-alumina (Al2O3), kaolinite (Al2Si2O5(OH)4), and montmorillonite (Na3(Al, Mg)2Si4O10(OH)2?nH2O). The results show that all of these materials can bind substantial quantities of hexavalent chromium, especially at low pH. Unexpectedly, experiments with the clay minerals kaolinite and montmorillonite suggest that hexavalent chromium may interact with these solids over much longer periods of time than expected. Furthermore, hexavalent chromium may irreversibly bind to these solids, perhaps because of oxidation-reduction reactions occurring on the surfaces of the clay minerals. More work should be done to investigate and quantify these chemical reactions. Experiments conducted with mixtures of goethite, hydrous manganese oxide, hydrous ferric oxide, ?-alumina, montmorillonite and kaolinite demonstrate that it is possible to correctly predict hexavalent chromium binding in the presence of multiple minerals using thermodynamic models derived for the simpler systems. Further, these models suggest that of the six solid considered in this study, goethite is typically the solid to which most of the hexavalent chromium will bind. Experiments completed with organic-rich and organic-poor natural sediments demonstrate that in organic-rich substrates, organic matter is likely to control uptake of the hexavalent chromium. The models derived and tested in this study for hexavalent chromium binding to ?-alumina, hydrous manganese oxide, goethite, hydrous ferric oxide and clay minerals can be used to better predict changes in hexavalent chromium bioavailability and mobility in contaminated sediments and soils.

  19. Ferrous Iron and Sulfur Oxidation and Ferric Iron Reduction Activities of Thiobacillus ferrooxidans Are Affected by Growth on Ferrous Iron, Sulfur, or a Sulfide Ore

    PubMed Central

    Suzuki, Isamu; Takeuchi, Travis L.; Yuthasastrakosol, Trin D.; Oh, Jae Key

    1990-01-01

    Eight strains of Thiobacillus ferrooxidans (laboratory strains Tf-1 [= ATCC 13661] and Tf-2 [= ATCC 19859] and mine isolates SM-1, SM-2, SM-3, SM-4, SM-5, and SM-8) and three strains of Thiobacillus thiooxidans (laboratory strain Tt [= ATCC 8085] and mine isolates SM-6 and SM-7) were grown on ferrous iron (Fe2+), elemental sulfur (S0), or sulfide ore (Fe, Cu, and Zn). The cells were studied for their aerobic Fe2+ - and S0-oxidizing activities (O2 consumption) and anaerobic S0-oxidizing activity with ferric iron (Fe3+) (Fe2+ formation). Fe2+-grown T. ferrooxidans cells oxidized S0 aerobically at a rate of 2 to 4% of the Fe2+ oxidation rate. The rate of anaerobic S0 oxidation with Fe3+ was equal to the aerobic oxidation rate in SM-1, SM-3, SM-4, and SM-5, but was only one-half or less that in Tf-1, Tf-2, SM-2, and SM-8. Transition from growth on Fe2+ to that on S0 produced cells with relatively undiminished Fe2+ oxidation activities and increased S0 oxidation (both aerobic and anaerobic) activities in Tf-2, SM-4, and SM-5, whereas it produced cells with dramatically reduced Fe2+ oxidation and anaerobic S0 oxidation activities in Tf-1, SM-1, SM-2, SM-3, and SM-8. Growth on ore 1 of metal-leaching Fe2+-grown strains and on ore 2 of all Fe2+-grown strains resulted in very high yields of cells with high Fe2+ and S0 oxidation (both aerobic and anaerobic) activities with similar ratios of various activities. Sulfur-grown Tf-2, SM-1, SM-4, SM-6, SM-7, and SM-8 cultures leached metals from ore 3, and Tf-2 and SM-4 cells recovered showed activity ratios similar to those of other ore-grown cells. It is concluded that all the T. ferrooxidans strains studied have the ability to produce cells with Fe2+ and S0 oxidation and Fe3+ reduction activities, but their levels are influenced by growth substrates and strain differences. PMID:16348205

  20. Enhanced functions of osteoblasts on nanophase ceramics

    Microsoft Academic Search

    Thomas J Webster; Celaletdin Ergun; Robert H Doremus; Richard W Siegel; Rena Bizios

    2000-01-01

    Select functions of osteoblasts (bone-forming cells) on nanophase (materials with grain sizes less than 100nm) alumina, titania, and hydroxyapatite (HA) were investigated using in vitro cellular models. Compared to conventional ceramics, surface occupancy of osteoblast colonies was significantly less on all nanophase ceramics tested in the present study after 4 and 6 days of culture. Osteoblast proliferation was significantly greater

  1. Iron-oxidizing bacteria are associated with ferric hydroxide precipitates (Fe-plaque) on the roots of wetland plants

    PubMed

    Emerson; Weiss; Megonigal

    1999-06-01

    The presence of Fe-oxidizing bacteria in the rhizosphere of four different species of wetland plants was investigated in a diverse wetland environment that had Fe(II) concentrations ranging from tens to hundreds of micromoles per liter and a pH range of 3.5 to 6.8. Enrichments for neutrophilic, putatively lithotrophic Fe-oxidizing bacteria were successful on roots from all four species; acidophilic Fe-oxidizing bacteria were enriched only on roots from plants whose root systems were exposed to soil solutions with a pH of <4. In Sagittaria australis there was a positive correlation (P < 0.01) between cell numbers and the total amount of Fe present; the same correlation was not found for Leersia oryzoides. These results present the first evidence for culturable Fe-oxidizing bacteria associated with Fe-plaque in the rhizosphere. PMID:10347074

  2. Iron-Oxidizing Bacteria Are Associated with Ferric Hydroxide Precipitates (Fe-Plaque) on the Roots of Wetland Plants

    PubMed Central

    Emerson, David; Weiss, Johanna V.; Megonigal, J. Patrick

    1999-01-01

    The presence of Fe-oxidizing bacteria in the rhizosphere of four different species of wetland plants was investigated in a diverse wetland environment that had Fe(II) concentrations ranging from tens to hundreds of micromoles per liter and a pH range of 3.5 to 6.8. Enrichments for neutrophilic, putatively lithotrophic Fe-oxidizing bacteria were successful on roots from all four species; acidophilic Fe-oxidizing bacteria were enriched only on roots from plants whose root systems were exposed to soil solutions with a pH of <4. In Sagittaria australis there was a positive correlation (P < 0.01) between cell numbers and the total amount of Fe present; the same correlation was not found for Leersia oryzoides. These results present the first evidence for culturable Fe-oxidizing bacteria associated with Fe-plaque in the rhizosphere. PMID:10347074

  3. Ferric sulfates on Mars

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.

    1987-01-01

    Evidence is presented for the possible existence of ferric sulfato complexes and hydroxo ferric sulfate minerals in the permafrost of Mars. A sequential combination of ten unique conditions during the cooling history of Mars is suggested which is believed to have generated an environment within Martian permafrost that has stabilized Fe(3+)-SO4(2-)-bearing species. It is argued that minerals belonging to the jarosite and copiapite groups could be present in Martian regolith analyzed in the Viking XRF measurements at Chryse and Utopia, and that maghemite suspected to be coating the Viking magnet arrays is a hydrolysate of dissolved ferric sulfato complexes from exposed Martian permafrost.

  4. Protein-Mediated Adhesion of the Dissimilatory Fe(III)-Reducing Bacterium Shewanella alga BrY to Hydrous Ferric Oxide

    PubMed Central

    Caccavo, Frank

    1999-01-01

    The rate and extent of bacterial Fe(III) mineral reduction are governed by molecular-scale interactions between the bacterial cell surface and the mineral surface. These interactions are poorly understood. This study examined the role of surface proteins in the adhesion of Shewanella alga BrY to hydrous ferric oxide (HFO). Enzymatic degradation of cell surface polysaccharides had no effect on cell adhesion to HFO. The proteolytic enzymes Streptomyces griseus protease and chymotrypsin inhibited the adhesion of S. alga BrY cells to HFO through catalytic degradation of surface proteins. Trypsin inhibited S. alga BrY adhesion solely through surface-coating effects. Protease and chymotrypsin also mediated desorption of adhered S. alga BrY cells from HFO while trypsin did not mediate cell desorption. Protease removed a single peptide band that represented a protein with an apparent molecular mass of 50 kDa. Chymotrypsin removed two peptide bands that represented proteins with apparent molecular masses of 60 and 31 kDa. These proteins represent putative HFO adhesion molecules. S. alga BrY adhesion was inhibited by up to 46% when cells were cultured at sub-MICs of chloramphenicol, suggesting that protein synthesis is necessary for adhesion. Proteins extracted from the surface of S. alga BrY cells inhibited adhesion to HFO by up to 41%. A number of these proteins bound specifically to HFO, suggesting that a complex system of surface proteins mediates S. alga BrY adhesion to HFO. PMID:10543817

  5. Protein-mediated adhesion of the dissimilatory Fe(III)-reducing bacterium Shewanella alga BrY to hydrous ferric oxide

    SciTech Connect

    Caccavo, F. Jr.

    1999-11-01

    The rate and extent of bacterial Fe(III) mineral reduction are governed by molecular-scale interactions between the bacterial cell surface and the mineral surface. These interactions are poorly understood. This study examined the role of surface proteins in the adhesion of Shewanella alga BrY to hydrous ferric oxide (HFO). Enzymatic degradation of cell surface polysaccharides had no effect on cell adhesion to HFO. The proteolytic enzymes Streptomyces griseus protease and chymotrypsin inhibited the adhesion of S. alga BrY cells to HFO through catalytic degradation of surface proteins. Trypsin inhibited S. alga BrY adhesion solely through surface-coating effects. Protease and chymotrypsin also mediated desorption of adhered S. alga BrY cells from HFO while trypsin did not mediate cell desorption. Protease removed a single peptide band that represented a protein with an apparent molecular mass of 50 kDa. Chymotrypsin removed two peptide bands that represented proteins with apparent molecular masses of 60 and 31 kDa. These proteins represent putative HGO adhesion molecules. A. alga BrY adhesion was inhibited by up to 46% when cells were cultured at sub-MICs of chloramphenicol, suggesting that protein synthesis is necessary for adhesion. Proteins extracted from the surface of S. alga BrY cells inhibited adhesion to HFO by up to 41%. A number of these proteins bound specifically to HFO, suggesting that a complex system of surface proteins mediates S. alga BrY adhesion to HFO.

  6. Effect of La{sub 2}O{sub 3}-treatment on textural and solid-solid interactions in ferric/cobaltic oxides system

    SciTech Connect

    Fagal, Gehan A. [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt)] [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt); Badawy, Abdelrahman A. [Physical Chemistry Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Dokki, Cairo (Egypt)] [Physical Chemistry Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Dokki, Cairo (Egypt); Hassan, Neven A. [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt)] [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt); El-Shobaky, Gamil A., E-mail: gamil_elshobaky@yahoo.com [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt)

    2012-10-15

    Pure and La{sub 2}O{sub 3}-containing (0.75-3.0 mol%) Fe{sub 2}O{sub 3}/Co{sub 3}O{sub 4} solids were prepared by thermal treatment of their carbonates at 500-700 Degree-Sign C. The produced solids were characterized using XRD, HRTEM, EDX and nitrogen adsorption at -196 Degree-Sign C. The results revealed that pure solids calcined at 600 and 700 Degree-Sign C consisted of nanosized CoFe{sub 2}O{sub 4} phase, while pure mixed solids calcined at 500 Degree-Sign C consisted of trace amount of CoFe{sub 2}O{sub 4} and unreacted Fe{sub 2}O{sub 3}, Co{sub 3}O{sub 4} phases. The presence of 0.75 mol% La{sub 2}O{sub 3} enhanced solid-solid interaction between Fe{sub 2}O{sub 3} and Co{sub 3}O{sub 4} at 500 Degree-Sign C yielding CoFe{sub 2}O{sub 4}. The ferrite phase existed also in all mixed oxides upon treated with La{sub 2}O{sub 3} besides LaCoO{sub 3} phase. LaCoO{sub 3} existed as a major phase in all mixed oxides treated with 3 mol% La{sub 2}O{sub 3}. La{sub 2}O{sub 3}-treatment modified the crystallite size of all phases present to an extent dependent on calcination temperature and amount of La{sub 2}O{sub 3} content. This treatment decreased effectively the S{sub BET} of all mixed solids. - Graphical Abstract: TEM photographs of pure mixed oxides calcined at 500 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer Cobalt ferrite exhibit chemical stability, low electric loss and high coercivity. Black-Right-Pointing-Pointer Cobalt ferrite is used in microwave devices, computer memories and magnetic storage. Black-Right-Pointing-Pointer Solid-solid interactions in ferric/cobaltic oxides system were investigated. Black-Right-Pointing-Pointer La{sub 2}O{sub 3}-treatment modified surface compositions of the system investigated. Black-Right-Pointing-Pointer All phases present in various solids existed as nanosized solids.

  7. Combined Hydrous Ferric Oxide and Quaternary Ammonium Surfactant Tailoring of Granular Activated Carbon for Concurrent Arsenate and Perchlorate Removal

    SciTech Connect

    Jang, M.; Cannon, F; Parette, R; Yoon, S; Chen, W

    2009-01-01

    Activated carbon was tailored with both iron and quaternary ammonium surfactants so as to concurrently remove both arsenate and perchlorate from groundwater. The iron (hydr)oxide preferentially removed the arsenate oxyanion but not perchlorate; while the quaternary ammonium preferentially removed the perchlorate oxyanion, but not the arsenate. The co-sorption of two anionic oxyanions via distinct mechanisms has yielded intriguing phenomena. Rapid small-scale column tests (RSSCTs) with these dually prepared media employed synthetic waters that were concurrently spiked with arsenate and perchlorate; and these trial results showed that the quaternary ammonium surfactants enhanced arsenate removal bed life by 25-50% when compared to activated carbon media that had been preloaded merely with iron (hydr)oxide; and the surfactant also enhanced the diffusion rate of arsenate per the Donnan effect. The authors also employed natural groundwater from Rutland, MA which contained 60 microg/L As and traces of silica, and sulfate; and the authors spiked this with 40 microg/L perchlorate. When processing this water, activated carbon that had been tailored with iron and cationic surfactant could treat 12,500 bed volumes before 10 microg/L arsenic breakthrough, and 4500 bed volumes before 6 microg/L perchlorate breakthrough. Although the quaternary ammonium surfactants exhibited only a slight capacity for removing arsenate, these surfactants did facilitate a more favorably positively charged avenue for the arsenate to diffuse through the media to the iron sorption site (i.e. via the Donnan effect).

  8. Nanophase materials assembled from clusters

    SciTech Connect

    Siegel, R.W.

    1992-02-01

    The preparation of metal and ceramic atom clusters by means of the gas-condensation method, followed by their in situ collection and consolidation under high-vacuum conditions, has recently led to the synthesis of a new class of ultrafine-grained materials. These nanophase materials, with typical average grain sizes of 5 to 50 nm and, hence, a large fraction of their atoms in interfaces, exhibit properties that are often considerably improved relative to those of conventional materials. Furthermore, their synthesis and processing characteristics should enable the design of new materials with unique properties. Some examples are ductile ceramics that can be formed and sintered to full density at low temperatures without the need for binding or sintering aids, and metals with dramatically increased strength. The synthesis of these materials is briefly described along with what is presently known of their structure and properties. Their future impact on materials science and technology is also considered.

  9. Ferric iron amendment increases Fe(III)-reducing microbial diversity and carbon oxidation in on-site wastewater systems.

    PubMed

    Azam, Hossain M; Finneran, Kevin T

    2013-01-01

    Onsite wastewater systems, or septic tanks, serve approximately 25% of the United States population; they are therefore a critical component of the total carbon balance for natural water bodies. Septic tanks operate under strictly anaerobic conditions, and fermentation is the dominant process driving carbon transformation. Nitrate, Fe(III), and sulfate reduction may be operating to a limited extent in any given septic tank. Electron acceptor amendments will increase carbon oxidation, but nitrate is toxic and sulfate generates corrosive sulfides, which may damage septic system infrastructure. Fe(III) reducing microorganisms transform all major classes of organic carbon that are dominant in septic wastewater: low molecular weight organic acids, carbohydrate monomers and polymers, and lipids. Fe(III) is not toxic, and the reduction product Fe(II) is minimally disruptive if the starting Fe(III) is added at 50-150 mg L(-1). We used (14)C radiolabeled acetate, lactate, propionate, butyrate, glucose, starch, and oleic acid to demonstrate that short and long-term carbon oxidation is increased when different forms of Fe(III) are amended to septic wastewater. The rates of carbon mineralization to (14)CO(2) increased 2-5 times (relative to unamended systems) in the presence of Fe(III). The extent of mineralization reached 90% for some carbon compounds when Fe(III) was present, compared to levels of 50-60% in the absence of Fe(III). (14)CH(4) was not generated when Fe(III) was added, demonstrating that this strategy can limit methane emissions from septic systems. Amplified 16S rDNA restriction analysis indicated that unique Fe(III)-reducing microbial communities increased significantly in Fe(III)-amended incubations, with Fe(III)-reducers becoming the dominant microbial community in several incubations. The form of Fe(III) added had a significant impact on the rate and extent of mineralization; ferrihydrite and lepidocrocite were favored as solid phase Fe(III) and chelated Fe(III) (with nitrilotriacetic acid or EDTA) as soluble Fe(III) forms. PMID:23062939

  10. Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

    1990-01-01

    Advanced oxide thermal barrier coatings have been developed by incorporating multi- component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma- sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia-yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging fiom 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

  11. Ferric Tourmaline from Mexico.

    PubMed

    Mason, B; Donnay, G; Hardie, L A

    1964-04-01

    Dark brown crystals, up to 10 mm long, occur in rhyolite at Mexquitic, San Luis Potosi, Mexico. They are short prismatic, showing {1120}, {3030}, {1011}, {0221}, with c/a 0.4521, measured with a goniometer, and distinct {1120} cleavage. With an unusual combination of cell dimensions, high density, high refractive indices, and extreme birefringence, this tourmaline falls outside the known elbaite-schorl and schorl-dravite series. A chemical analysis, recalculated on the basis of cell volume and density, gives close to the theoretical 150 atoms per cell, whether the iron is ferrous or ferric, but the physical properties indicate a ferric tourmaline. PMID:17729799

  12. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...resulting from mixing solutions of ferrous sulfate and sodium ferrocyanide in the presence of ammonium sulfate. The oxidized product is filtered, washed...pigment consists principally of ferric ammonium ferrocyanide with smaller amounts of...

  13. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...resulting from mixing solutions of ferrous sulfate and sodium ferrocyanide in the presence of ammonium sulfate. The oxidized product is filtered, washed...pigment consists principally of ferric ammonium ferrocyanide with smaller amounts of...

  14. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...resulting from mixing solutions of ferrous sulfate and sodium ferrocyanide in the presence of ammonium sulfate. The oxidized product is filtered, washed...pigment consists principally of ferric ammonium ferrocyanide with smaller amounts of...

  15. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...resulting from mixing solutions of ferrous sulfate and sodium ferrocyanide in the presence of ammonium sulfate. The oxidized product is filtered, washed...pigment consists principally of ferric ammonium ferrocyanide with smaller amounts of...

  16. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...resulting from mixing solutions of ferrous sulfate and sodium ferrocyanide in the presence of ammonium sulfate. The oxidized product is filtered, washed...pigment consists principally of ferric ammonium ferrocyanide with smaller amounts of...

  17. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Ferric phosphate. 184.1301 Section 184.1301 Food and...Substances Affirmed as GRAS § 184.1301 Ferric phosphate. (a) Ferric phosphate (ferric orthophosphate, iron (III)...

  18. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Ferric phosphate. 184.1301 Section 184.1301 Food and...Substances Affirmed as GRAS § 184.1301 Ferric phosphate. (a) Ferric phosphate (ferric orthophosphate, iron (III)...

  19. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Ferric phosphate. 184.1301 Section 184.1301 Food and...Substances Affirmed as GRAS § 184.1301 Ferric phosphate. (a) Ferric phosphate (ferric orthophosphate, iron (III)...

  20. Nanophase materials assembled from atom clusters

    SciTech Connect

    Siegel, R.W.

    1992-12-01

    Nanometer-scale atom clusters (with average diameters below 20 nm) of a variety of materials, including both metals and ceramics, have been synthesized by precursor evaporation and condensation in high-purity gases. The gas-entrained clusters can be collected and subsequently consolidated in situ under ultrahigh vacuum or other controlled atmosphere conditions to create bulk nanophase materials. These ultrafine-grained materials have properties that are often significantly different and considerably improved relative to those of their coarser-grained counterparts. The observed property changes relate to both their small grain sizes and the large percentage of their atoms in grain boundary environments. Since it is becoming apparent that their properties can be engineered during gas-phase synthesis and subsequent processing, nanophase materials assembled from atom clusters should have significant potential for technological development in a variety of applications. Some of the recent research on nanophase materials is reviewed.

  1. Synthesis and properties of nanophase materials

    SciTech Connect

    Siegel, R.W.

    1993-03-01

    Nanophase materials, with their grain sizes or phase dimensions in the nanometer size regime, are now being produced by a wide variety of synthesis and processing methods. The interest in these new ultrafine-grained materials results primarily from the special nature of their various physical, chemical, and mechanical properties and the possibilities to control these properties during the synthesis and subsequent processing procedures. Since it is now becoming increasingly apparent that their properties can be engineered effectively during synthesis and processing, and that they can also be produced in quantity, nanophase materials should have considerable potential for technological development in a variety of applications. Some of the recent research on nanophase materials related to their synthesis and properties is briefly reviewed and the future potential of these new materials is considered.

  2. Nanophase change for data storage applications.

    PubMed

    Shi, L P; Chong, T C

    2007-01-01

    Phase change materials are widely used for date storage. The most widespread and important applications are rewritable optical disc and Phase Change Random Access Memory (PCRAM), which utilizes the light and electric induced phase change respectively. For decades, miniaturization has been the major driving force to increase the density. Now the working unit area of the current data storage media is in the order of nano-scale. On the nano-scale, extreme dimensional and nano-structural constraints and the large proportion of interfaces will cause the deviation of the phase change behavior from that of bulk. Hence an in-depth understanding of nanophase change and the related issues has become more and more important. Nanophase change can be defined as: phase change at the scale within nano range of 100 nm, which is size-dependent, interface-dominated and surrounding materials related. Nanophase change can be classified into two groups, thin film related and structure related. Film thickness and clapping materials are key factors for thin film type, while structure shape, size and surrounding materials are critical parameters for structure type. In this paper, the recent development of nanophase change is reviewed, including crystallization of small element at nano size, thickness dependence of crystallization, effect of clapping layer on the phase change of phase change thin film and so on. The applications of nanophase change technology on data storage is introduced, including optical recording such as super lattice like optical disc, initialization free disc, near field, super-RENS, dual layer, multi level, probe storage, and PCRAM including, superlattice-like structure, side edge structure, and line type structure. Future key research issues of nanophase change are also discussed. PMID:17455476

  3. Transcriptional and Proteomic Analysis of a Ferric Uptake Regulator (Fur) Mutant of Shewanella oneidensis: Possible Involvement of Fur in Energy Metabolism, Transcriptional Regulation, and Oxidative Stress

    Microsoft Academic Search

    Dorothea K. Thompson; Alexander S. Beliaev; Carol S. Giometti; Sandra L. Tollaksen; Tripti Khare; Douglas P. Lies; Kenneth H. Nealson; Hanjo Lim; John Yates; Craig C. Brandt; James M. Tiedje; Jizhong Zhou

    2002-01-01

    The iron-directed, coordinate regulation of genes depends on the fur (ferric uptake regulator) gene product, which acts as an iron-responsive, transcriptional repressor protein. To investigate the biological function of a fur homolog in the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1, a fur knockout strain (FUR1) was generated by suicide plasmid integration into this gene and characterized using phenotype assays, DNA

  4. Adhesion of Pseudomonas fluorescens onto nanophase materials

    NASA Astrophysics Data System (ADS)

    Webster, Thomas J.; Tong, Zonghua; Liu, Jin; Banks, M. Katherine

    2005-07-01

    Nanobiotechnology is a growing area of research, primarily due to the potentially numerous applications of new synthetic nanomaterials in engineering/science. Although various definitions have been given for the word 'nanomaterials' by many different experts, the commonly accepted one refers to nanomaterials as those materials which possess grains, particles, fibres, or other constituent components that have one dimension specifically less than 100 nm. In biological applications, most of the research to date has focused on the interactions between mammalian cells and synthetic nanophase surfaces for the creation of better tissue engineering materials. Although mammalian cells have shown a definite positive response to nanophase materials, information on bacterial interactions with nanophase materials remains elusive. For this reason, this study was designed to assess the adhesion of Pseudomonas fluorescens on nanophase compared to conventional grain size alumina substrates. Results provide the first evidence of increased adhesion of Pseudomonas fluorescens on alumina with nanometre compared to conventional grain sizes. To understand more about the process, polymer (specifically, poly-lactic-co-glycolic acid or PLGA) casts were made of the conventional and nanostructured alumina surfaces. Results showed similar increased Pseudomonas fluorescens capture on PLGA casts of nanostructured compared to conventional alumina as on the alumina itself. For these reasons, a key material property shown to enhance bacterial adhesion was elucidated in this study for both polymers and ceramics: nanostructured surface features.

  5. Functionally Graded Nanophase Beryllium/Carbon Composites

    NASA Technical Reports Server (NTRS)

    Voronov, Oleg A.; Tompa, Gary S.

    2003-01-01

    Beryllium, beryllium alloys, beryllium carbide, and carbon are the ingredients of a class of nanophase Be/Be2C/C composite materials that can be formulated and functionally graded to suit a variety of applications. In a typical case, such a composite consists of a first layer of either pure beryllium or a beryllium alloy, a second layer of B2C, and a third layer of nanophase sintered carbon derived from fullerenes and nanotubes. The three layers are interconnected through interpenetrating spongelike structures. These Be/Be2C/C composite materials are similar to Co/WC/diamond functionally graded composite materials, except that (1) W and Co are replaced by Be and alloys thereof and (2) diamond is replaced by sintered carbon derived from fullerenes and nanotubes. (Optionally, one could form a Be/Be2C/diamond composite.) Because Be is lighter than W and Co, the present Be/Be2C/C composites weigh less than do the corresponding Co/WC/diamond composites. The nanophase carbon is almost as hard as diamond. WC/Co is the toughest material. It is widely used for drilling, digging, and machining. However, the fact that W is a heavy element (that is, has high atomic mass and mass density) makes W unattractive for applications in which weight is a severe disadvantage. Be is the lightest tough element, but its toughness is less than that of WC/Co alloy. Be strengthened by nanophase carbon is much tougher than pure or alloy Be. The nanophase carbon has an unsurpassed strength-to-weight ratio. The Be/Be2C/C composite materials are especially attractive for terrestrial and aerospace applications in which there are requirements for light weight along with the high strength and toughness of the denser Co/WC/diamond materials. These materials could be incorporated into diverse components, including cutting tools, bearings, rocket nozzles, and shields. Moreover, because Be and C are effective as neutron moderators, Be/Be2C/C composites could be attractive for some nuclear applications.

  6. Molecular Structure of Ferric chloride

    NSDL National Science Digital Library

    2002-08-27

    Ferric chloride is a corrosive chemical, thus, it is used to deodorize sewage and industrial waste by partially reducing to ferrous chloride. It is also employed as an engraving reagent on metal surfaces. Other applications include its use as a flocculating agent in water treatment. Ferric chloride is a hazardous chemical that irritates the skin and eyes and is toxic if ingested, however it can be used as a reagent in pharmaceutical preparations.

  7. Ferrous Ferric Chloride Induces the Differentiation of Cultured Mouse Epidermal Melanocytes Additionally with Herbal Medicines

    Microsoft Academic Search

    Tomohisa Hirobe

    2009-01-01

    Ferrous ferric chloride (FFC) is a special form of aqueous iron that is a complex of ferrous chloride and ferric chloride and participates in oxidation and reduction reactions. My previous study showed that FFC stimulated the proliferation and differentiation of cultured epidermal melanoblasts or melanocytes derived from newborn mice. However, it is not known whether FFC stimulates the proliferation and

  8. Reflectance spectroscopy of ferric sulfate-bearing montmorillonites as Mars soil analog materials

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Pieters, C. M.; Burns, R. G.; Edwards, J. O.; Mancinelli, R. L.; Froschl, H.

    1995-01-01

    Spectroscopic analyses have shown that smectites enhanced in the laboratory with additional ferric species exhibit important similarities to those of the soils on Mars. Ferrihydrite in these chemically treated smectites has features in the visible to near-infrared region that resemble the energies and band strengths of features in reflectance spectra observed for several bright regions on Mars. New samples have been prepared with sulfate as well, because S was found by Viking to be a major component in the surface material on Mars. A suite of ferrihydrite-bearing and ferric sulfate-bearing montmorillonites, prepared with variable Fe3+ and S concentrations and variable pH conditions, has been analyzed using reflectance spectroscopy in the visible and infrared regions, Mossbauer spectroscopy at room temperature and 4 K, differential thermal analysis, and X-ray diffraction. These analyses support the formation of ferrihydrite of variable crystallinity in the ferrihydrite-bearing montmorillonites and a combination of schwertmannite and ferrihydrite in the ferric sulfate-bearing montmorillonites. Small quantities of poorly crystalline or nanophase forms of other ferric materials may also be present in these samples. The chemical formation conditions of the ferrihydrite-bearing and ferric sulfate-bearing montmorillonites influence the character of the low temperature Mossbauer sextets and the visible reflectance spectra. An absorption minimum is observed at 0.88-0.89 micrometers in spectra of the ferric sulfate-bearing samples, and at 0.89-0.92 micrometers in spectra of the ferrihydrate-bearing montmorillonites. Mossbauer spectra of the ferric sulfate-bearing montmorillonites indicate variable concentrations of ferrihydrite and schwertmannite in the interlaminar spaces and along grain surfaces. Dehydration under reduced atmospheric pressure conditions induces a greater effect on the adsorbed and interlayer water in ferrihydrite-bearing montmorillonite than on the water in ferric sulfate-bearing montmorillonite. Reflectance spectra of ferric sulfate-bearing montmorillonite include a strong 3-micrometers band that is more resistant to dry atmospheric conditions than the 3-micrometers band in spectra of similarly prepared ferrihydrite-bearing montmorillonites.

  9. Detecting Nanophase Weathering Products with CheMin: Reference Intensity Ratios of Allophane, Aluminosilicate Gel, and Ferrihydrite

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Bish, D. L.; Chipera, S. J.; Morris, R. V.; Achilles, C. N.; Ming, D W.; Blake, D. F.; Anderson, R. C.; Bristow, T. F.; Crisp, A.; DesMarais, D. J.; Downs, R. T.; Farmer, J. D.; Morookian, J. M.; Morrison, S. M.; Sarrazin, P.; Spanovich, N.; Stolper, E. M.; Treiman, A. H.; Vaniman, D. T.; Yen, A. S.

    2013-01-01

    X-ray diffraction (XRD) data collected of the Rocknest samples by the CheMin instrument on Mars Science Laboratory suggest the presence of poorly crystalline or amorphous materials [1], such as nanophase weathering products or volcanic and impact glasses. The identification of the type(s) of X-ray amorphous material at Rocknest is important because it can elucidate past aqueous weathering processes. The presence of volcanic and impact glasses would indicate that little chemical weathering has occurred because glass is highly susceptible to aqueous alteration. The presence of nanophase weathering products, such as allophane, nanophase iron-oxides, and/or palagonite, would indicate incipient chemical weathering. Furthermore, the types of weathering products present could help constrain pH conditions and identify which primary phases altered to form the weathering products. Quantitative analysis of phases from CheMin data is achieved through Reference Intensity Ratios (RIRs) and Rietveld refinement. The RIR of a mineral (or mineraloid) that relates the scattering power of that mineral (typically the most intense diffraction line) to the scattering power of a separate mineral standard such as corundum [2]. RIRs can be calculated from XRD patterns measured in the laboratory by mixing a mineral with a standard in known abundances and comparing diffraction line intensities of the mineral to the standard. X-ray amorphous phases (e.g., nanophase weathering products) have broad scattering signatures rather than sharp diffraction lines. Thus, RIRs of X-ray amorphous materials are calculated by comparing the area under one of these broad scattering signals with the area under a diffraction line in the standard. Here, we measured XRD patterns of nanophase weathering products (allophane, aluminosilicate gel, and ferrihydrite) mixed with a mineral standard (beryl) in the CheMinIV laboratory instrument and calculated their RIRs to help constrain the abundances of these phases in the Rocknest samples.

  10. Ferric hydroxide and ferric hydroxysulfate precipitation by bacteria in an acid mine drainage lagoon

    E-print Network

    Konhauser, Kurt

    Ferric hydroxide and ferric hydroxysulfate precipitation by bacteria in an acid mine drainage communities growing in an acid mine drainage lagoon sediment has confirmed that microorganisms were also: Ferrihydrite; Ferric hydroxysulfate; Bacteria; Biomineralization; Acid mine drainage Contents 1. Introduction

  11. ESTCP DEMONSTRATION OF A BIOAVAILABLE FERRIC IRON TEST KIT

    EPA Science Inventory

    Bioavailable ferric iron (BAFeIII) is used by iron-reducing bacteria as an electron acceptor during the oxidation of various organic contaminants such as vinyl chloride and benzene. Quantification of BAFeIII is important with respect to characterizing candidate natural attenuati...

  12. Uranium extraction using biogenic ferric sulfate a case study on quartz chlorite ore from Jaduguda, Singhbhum Thrust Belt (STB), Bihar, India

    Microsoft Academic Search

    A. K. Mathur; K. Viswamohan; K. B. Mohanty; V. K. Murthy; S. T. Seshadrinath

    2000-01-01

    The application of ferric ion as an oxidant and in combination with other anions such as ferric sulfate or chloride as cr leachant is well accepted for the recovery of metals, particularly from ores of copper, cobalt, nickel, lead, zinc and uranium. Biogenically generated ferric sulfate has been in vogue for many dump and heap leaching operations, to recover uranium

  13. Influence of nanophase titania topography on bacterial attachment and metabolism

    PubMed Central

    Park, Margaret R; Banks, Michelle K; Applegate, Bruce; Webster, Thomas J

    2008-01-01

    Surfaces with nanophase compared to conventional (or nanometer smooth) topographies are known to have different properties of area, charge, and reactivity. Previously published research indicates that the attachment of certain bacteria (such as Pseudomonas fluorescens 5RL) is higher on surfaces with nanophase compared to conventional topographies, however, their effect on bacterial metabolism is unclear. Results presented here show that the adhesion of Pseudomonas fluorescens 5RL and Pseudomonas putida TVA8 was higher on nanophase than conventional titania. Importantly, in terms of metabolism, bacteria attached to the nanophase surfaces had higher bioluminescence rates than on the conventional surfaces under all nutrient conditions. Thus, the results from this study show greater select bacterial metabolism on nanometer than conventional topographies, critical results with strong consequences for the design of improved biosensors for bacteria detection. PMID:19337418

  14. Postdoctoral Research Associate Center for Nanophase Materials Sciences

    E-print Network

    Pennycook, Steve

    University Graduate Fellowship Graduate and Postdoctoral Advisors: Postdoctoral Advisor: Dr. Chengdu Liang1 Hui Wang Postdoctoral Research Associate Center for Nanophase Materials Sciences Oak Ridge nanomaterials structure and catalytic functions; Preparation of novel materials for energy applications

  15. Formation of structured nanophases in halide crystals.

    PubMed

    Kulveit, J; Demo, P; Polák, K; Sveshnikov, A M; Kožíšek, Z

    2011-04-14

    When halide crystals KCl and NaCl are slightly doped by PbCl(2), (in orders of 10(-4)?mol/mol) the structurally stable nanophases ("quantum dots") are formed via nucleation within the bulks of their matrices. Using lattice modeling we have found in KCl-Pb system natural nucleation pathway from single impurity-vacancy complex to Suzuki phase, not demonstrated in previous analyses; further transition to PbCl(2) is difficult due to high stability of this phase. In the case of NaCl-Pb, no stable "end point" of aggregation was observed and our calculations suggest nucleation may readily proceed to large PbCl(2) clusters when initially formed platelike cluster reaches a certain critical thickness. These results coincide with our experimental data. PMID:21495761

  16. Formation of structured nanophases in halide crystals

    NASA Astrophysics Data System (ADS)

    Kulveit, J.; Demo, P.; Polák, K.; Sveshnikov, A. M.; Kožíšek, Z.

    2011-04-01

    When halide crystals KCl and NaCl are slightly doped by PbCl_2, (in orders of 10^{-4} mol/mol) the structurally stable nanophases ("quantum dots") are formed via nucleation within the bulks of their matrices. Using lattice modeling we have found in KCl-Pb system natural nucleation pathway from single impurity-vacancy complex to Suzuki phase, not demonstrated in previous analyses; further transition to PbCl_2 is difficult due to high stability of this phase. In the case of NaCl-Pb, no stable "end point" of aggregation was observed and our calculations suggest nucleation may readily proceed to large PbCl_2 clusters when initially formed platelike cluster reaches a certain critical thickness. These results coincide with our experimental data.

  17. Hydrogen Storage in Nano-Phase Diamond at High Temperature and Its Release

    SciTech Connect

    Tushar K Ghosh

    2008-10-13

    The objectives of this proposed research were: 91) Separation and storage of hydrogen on nanophase diamonds. It is expected that the produced hydrogen, which will be in a mixture, can be directed to a nanophase diamond system directly, which will not only store the hydrogen, but also separate it from the gas mixture, and (2) release of the stored hydrogen from the nanophase diamond.

  18. The Bradyrhizobium japonicum frcB Gene Encodes a Diheme Ferric Reductase ?†

    PubMed Central

    Small, Sandra K.; O'Brian, Mark R.

    2011-01-01

    Iron utilization by bacteria in aerobic environments involves uptake as a ferric chelate from the environment, followed by reduction to the ferrous form. Ferric iron reduction is poorly understood in most bacterial species. Here, we identified Bradyrhizobium japonicum frcB (bll3557) as a gene adjacent to, and coregulated with, the pyoR gene (blr3555) encoding the outer membrane receptor for transport of a ferric pyoverdine. FrcB is a membrane-bound, diheme protein, characteristic of eukaryotic ferric reductases. Heme was essential for FrcB stability, as were conserved histidine residues in the protein that likely coordinate the heme moieties. Expression of the frcB gene in Escherichia coli conferred ferric reductase activity on those cells. Furthermore, reduced heme in purified FrcB was oxidized by ferric iron in vitro. B. japonicum cells showed inducible ferric reductase activity in iron-limited cells that was diminished in an frcB mutant. Steady-state levels of frcB mRNA were strongly induced under iron-limiting conditions, but transcript levels were low and unresponsive to iron in an irr mutant lacking the global iron response transcriptional regulator Irr. Thus, Irr positively controls the frcB gene. FrcB belongs to a family of previously uncharacterized proteins found in many proteobacteria and some cyanobacteria. This suggests that membrane-bound, heme-containing ferric reductase proteins are not confined to eukaryotes but may be common in bacteria. PMID:21705608

  19. Adverse reactions of ferric carboxymaltose.

    PubMed

    Thanusubramanian, Harish; Patil, Navin; Shenoy, Smita; Bairy, K L; Sarma, Yashdeep

    2014-10-01

    The author reports a 55-year-old female diagnosed of chronic kidney disease grade-5 with associated co-morbidities like type 2 diabetes mellitus, diabetic retinopathy and hypothyroidism was admitted for arteriovenous fistula construction. She was started on ferric carboxymaltose for the treatment of anaemia. She was given a test dose before administering the drug intravenously and she did not develop any reaction. The drug ferric carboxymaltose was then administered over a period of one hour. About half an hour after drug administration, the patient developed breathlessness and myalgia. After half hour of the above episode of breathlessness and myalgia she also developed vomiting (one episode). Patient was managed with oxygen therapy, IV fluids and other drugs like corticosteroids, phenaramine maleate and nalbuphine which controlled the above symptoms. PMID:25478369

  20. Hydrogen Reduction of Ferric Ions for Use in Copper Electrowinning

    SciTech Connect

    Karl S. Noah; Debby F. Bruhn; John E. Wey; Robert S. Cherry

    2005-01-01

    The conventional copper electrowinning process uses the water hydrolysis reaction as the anodic source of electrons. However this reaction generates acid mist and requires large quantities of energy. In order to improve energy efficiency and avoid acid mist, an alternative anodic reaction of ferrous ion oxidation has been proposed. This reaction does not involve evolution of acid mist and can be carried out at a lower cell voltage than the conventional process. However, because ferrous ions are converted to ferric ions at the anode in this process, there is a need for reduction of ferric ions to ferrous ions to continue this process. The most promising method for this reduction is the use of hydrogen gas since the resulting byproduct acid can be used elsewhere in the process and, unlike other reductants, hydrogen does not introduce other species that need subsequent removal. Because the hydrogen reduction technology has undergone only preliminary lab scale testing, additional research is needed to evaluate its commercial potential. Two issues for this research are the potentially low mass transfer rate of hydrogen into the electrolyte stream because of its low solubility in water, and whether other gaseous reductants less expensive than hydrogen, such as natural gas or syngas, might work. In this study various reductants were investigated to carry out the reduction of ferric ions to ferrous ions using a simulated electrolyte solution recycled through a trickle bed reactor packed with catalyst. The gases tested as reductants were hydrogen, methane, carbon monoxide, and a 50/50 mixture of H2 and CO. Nitrogen was also tested as an inert control. These gases were tested because they are constituents in either natural gas or syngas. The catalysts tested were palladium and platinum. Two gas flow rates and five electrolyte flow rates were tested. Pure hydrogen was an effective reductant of ferric ion. The rates were similar with both palladium and platinum. The ferric iron reduction increased with both the flow rate of gas as well as the liquid flow rate (up to ~0.1 g/L/min). Pure carbon monoxide also reduced the ferric ion, but at a rate about one tenth that of pure hydrogen at similar conditions. The syngas mixture of equimolar hydrogen and carbon monoxide reacted at a rate intermediate between each gas as a pure stream (up to ~ 0.06 g/L/min). This gas mixture shows that some form of unpurified reformer gas could be used to reduce the ferric ion in the electrolyte solution. Nitrogen was inert causing very little to no reduction of ferric ion.

  1. Superhard nanophase cutter materials for rock drilling applications

    SciTech Connect

    Voronov, O.; Tompa, G.; Sadangi, R.; Kear, B.; Wilson, C.; Yan, P.

    2000-06-23

    The Low Pressure-High Temperature (LPHT) System has been developed for sintering of nanophase cutter and anvil materials. Microstructured and nanostructured cutters were sintered and studied for rock drilling applications. The WC/Co anvils were sintered and used for development of High Pressure-High Temperature (HPHT) Systems. Binderless diamond and superhard nanophase cutter materials were manufactured with help of HPHT Systems. The diamond materials were studied for rock machining and drilling applications. Binderless Polycrystalline Diamonds (BPCD) have high thermal stability and can be used in geothermal drilling of hard rock formations. Nanophase Polycrystalline Diamonds (NPCD) are under study in precision machining of optical lenses. Triphasic Diamond/Carbide/Metal Composites (TDCC) will be commercialized in drilling and machining applications.

  2. Resonance Raman studies of nitric oxide binding to ferric and ferrous hemoproteins: detection of Fe(III)--NO stretching, Fe(III)--N--O bending, and Fe(II)--N--O bending vibrations.

    PubMed Central

    Benko, B; Yu, N T

    1983-01-01

    The nature of bonding interactions between Fe(III) and NO in the ferric nitrosyl complexes of myoglobin (Mb), hemoglobin A (HbA), and horseradish peroxidase (HRP) is investigated by Soret-excited resonance Raman spectroscopy. On the basis of 15NO and N18O isotope shifts, we clearly identified the Fe(III)--NO bond stretching frequencies at 595 cm-1 (ferric Mb X NO), 594 cm-1 (ferric HbA X NO), and 604 cm-1 (ferric HRP X NO). The Fe(III)--N--O bending vibrations are located at 573 cm-1 (ferric Mb X NO) and 574 cm-1 (ferric HRP X NO), which are very similar to the Fe(II)--C--O bending modes at 578 cm-1 in Mb X CO and HbA X CO. However, the Fe(III)--NO and Fe(II)--CO stretching frequencies differ by approximately equal to 90 cm-1, indicating a much stronger iron-axial ligand bond for the [Fe(III) + NO] system, which is isoelectronic with the [Fe(II) + CO] system and, hence, presumably also has a linear Fe(III)--N--O linkage (in the absence of distal steric effect). The unusually strong Fe(III)--NO bond may be attributed to the pi bonding involving the unpaired electron in the pi (NO) orbital. The N18O isotope shift data indicate that the widely accepted assignment of the Fe(II)--NO stretching vibration at approximately equal to 554 cm-1 in ferrous nitrosyl Mb/HbA is incorrect; instead, we assign it to the Fe(II)--N--O bending mode. The validity of the assignment of Fe(II)--O2 stretch at 567 cm-1 in oxy-HbA by Brunner [Brunner, H. (1974) Naturwissenschaften 61, 129-130] is now in doubt. Literature data are presented to suggest that it is the Fe(II)--O--O bending vibration. PMID:6580627

  3. Method of treating inflammatory diseases using a radiolabeled ferric hydroxide calloid

    DOEpatents

    Atcher, Robert W. (Chicago, IL); Hines, John J. (Glen Ellyn, IL)

    1992-01-01

    A ferric hydroxide colloid having an alpha-emitting radionuclide essentially on the outer surfaces and a method of forming same. The method includes oxidizing a ferrous hydroxide to ferric hydroxide in the presence of a preselected radionuclide to form a colloid having the radionuclide on the outer surface thereof, and thereafter washing the colloid, and suspending the washed colloid in a suitable solution. The labelled colloid is useful in cancer therapy and for the treatment of inflamed joints.

  4. Glyphosate inhibition of ferric reductase activity in iron deficient sunflower roots.

    PubMed

    Ozturk, Levent; Yazici, Atilla; Eker, Selim; Gokmen, Ozgur; Römheld, Volker; Cakmak, Ismail

    2008-01-01

    Iron (Fe) deficiency is increasingly being observed in cropping systems with frequent glyphosate applications. A likely reason for this is that glyphosate interferes with root uptake of Fe by inhibiting ferric reductase in roots required for Fe acquisition by dicot and nongrass species. This study investigated the role of drift rates of glyphosate (0.32, 0.95 or 1.89 mm glyphosate corresponding to 1, 3 and 6% of the recommended herbicidal dose, respectively) on ferric reductase activity of sunflower (Helianthus annuus) roots grown under Fe deficiency conditions. Application of 1.89 mm glyphosate resulted in almost 50% inhibition of ferric reductase within 6 h and complete inhibition 24 h after the treatment. Even at lower rates of glyphosate (e.g. 0.32 mm and 0.95 mm), ferric reductase was inhibited. Soluble sugar concentration and the NAD(P)H oxidizing capacity of apical roots were not decreased by the glyphosate applications. To our knowledge, this is the first study reporting the effects of glyphosate on ferric reductase activity. The nature of the inhibitory effect of glyphosate on ferric reductase could not be identified. Impaired ferric reductase could be a major reason for the increasingly observed Fe deficiency in cropping systems associated with widespread glyphosate usage. PMID:18179601

  5. Post.Doc Researcher Center for Nanophase Materials Sciences

    E-print Network

    Pennycook, Steve

    Youjun He Post.Doc Researcher Center for Nanophase Materials Sciences Oak Ridge National Laboratory National Laboratory. Post. Doc Researcher. 2010, 08-2011, 12 University of California, Los Angeles. Post. Doc Researcher. Research Synopsis: 1. Conjugated Polymer Donor Materials for Polymeric Solar Cell

  6. Effects of Nanophase Materials (?20 nm) on Biological Responses

    Microsoft Academic Search

    Meng-Dawn Cheng

    2004-01-01

    Nanophase materials have enhanced properties (thermal, mechanical, electrical, surface reactivity, etc.) not found in bulk materials. Intuitively, the enhancement of material properties could occur when the materials encounter biological specimens. Previous investigations of biological interactions with nanometer-scale materials have been very limited. With the ability to manipulate atoms and molecules, we now can create predefined nanostructures with unprecedented precision. In

  7. Hematite, pyroxene, and phyllosilicates on Mars: Implications from oxidized impact melt rocks from Manicouagan Crater, Quebec, Canada

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Golden, D. C.; Bell, James F., III; Lauer, H. V., Jr.

    1995-01-01

    Visible and near-IR reflectivity, Mossbauer, and X ray diffraction data were obtained on powders of impact melt rock from the Manicouagan Impact Crater located in Quebec, Canada. The iron mineralogy is dominated by pyroxene for the least oxidized samples and by hematite for the most oxidized samples. Phyllosilicate (smectite) contents up to 15 wt % were found in some heavily oxidized samples. Nanophase hematite and/or paramagnetic ferric iron is observed in all samples. No hydrous ferric oxides (e.g., goethite, lepidocrocite, and ferrihydrite) were detected, which implies the alteration occurred above 250 C. Oxidative alteration is thought to have occurred predominantly during late-stage crystallization and subsolidus cooling of the impact melt by invasion of oxidizing vapors and/or solutions while the impact melt rocks were still hot. The near-IR band minimum correlated with the extent of aleration (Fe(3+)/Fe(sub tot)) and ranged from approx. 1000 nm (high-Ca pyroxene) to approx. 850 nm (bulk, well-crystalline hematite) for least and most oxidized samples, respectively. Intermediate band positions (900-920 nm) are attributed to low-Ca pyroxene and/or a composite band from hematite-pyroxene assemblages. Manicouagan data are consistent with previous assignments of hematite and pyroxene to the 850 and 1000 nm bands observed in Martian reflectivity spectra. Manicouagan data also show that possible assignments for intermediate band positions (900-920 nm) in Martian spectra are pyroxene and/or hematite-pyroxene assemblages. By analogy with impact melt sheets and in agreement with observables for Mars, oxidative alteration of Martian impact melt sheets above 250 C and subsequent erosion could produce rocks and soils with variable proportions of hematite (both bulk and nanophase), pyroxene, and phyllosilicates as iron-bearing mineralogies. If this process is dominant, these phases on Mars were formed rapidly at relatively high temperatures on a sporadic basis throughout the history of the planet. The Manicouagan samples also show that this mineralogical diversity can be accomplished at constant chemical composition, which is also indicated for Mars from analyses of soil at the two Viking landing sites.

  8. Hematite, pyroxene, and phyllosilicates on Mars: Implications from oxidized impact melt rocks from Manicouagan Crater, Quebec, Canada

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Golden, D. C.; Bell, James F., III; Lauer, H. V., Jr.

    1995-01-01

    Visible and near-IR refectivity, Moessbauer, and X ray diffraction data were obtained on powders of impact melt rock from the Manicouagan Impact Crater located in Quebec, Canada. The iron mineralogy is dominated by pyroxene for the least oxidized samples and by hematite for the most oxidized samples. Phyllosilicate (smectite) contents up to approximately 15 wt % were found in some heavily oxidized samples. Nanophase hematite and/or paramagnetic ferric iron is observed in all samples. No hydrous ferric oxides (e.g., goethite, lepidocrocite, and ferrihydrite) were detected, which implies the alteration occurred above 250 C. Oxidative alteration is thought to have occurred predominantly during late-stage crystallization and subsolidus cooling of the impact melt by invasion of oxidizing vapors and/or solutions while the impact melt rocks were still hot. The near-IR band minimum correlated with the extent of aleration Fe(3+)/Fe(sub tot) and ranged from approximately 1000 nm (high-Ca pyroxene) to approximately 850 nm (bulk, well-crystalline hematite) for least and most oxidized samples, respectively. Intermediate band positions (900-920 nm) are attributed to low-Ca pyroxene and/or a composite band from hematite-pyroxene assemblages. Manicouagan data are consistent with previous assignments of hematite and pyroxene to the approximately 850 and approximately 1000nm bands observed in Martian reflectivity spectra. Manicouagan data also show that possible assignments for intermediate band positions (900-920 nm) in Martian spectra are pyroxene and/or hematite-pyroxene assemblages. By analogy with impact melt sheets and in agreement with observables for Mars, oxidative alteration of Martian impact melt sheets above 250 C and subsequent erosion could produce rocks and soils with variable proportions of hematite (both bulk and nanophase), pyroxene, and phyllosilicates as iron-bearing mineralogies. If this process is dominant, these phases on Mars were formed rapidly at relativly high temperatures on a sporadic basis throughout the history of the planet. The Manicouagan samples also show that this mineralogical diversity can be accomplished at constant chemical composition, which is also indicated for Mars from the analyses of soil at the two Viking landing sites.

  9. Hematite, pyroxene, and phyllosilicates on Mars: Implications from oxidized impact melt rocks from Manicouagan Crater, Quebec, Canada

    NASA Astrophysics Data System (ADS)

    Morris, Richard V.; Golden, D. C.; Bell, James F., III; Lauer, H. V., Jr.

    1995-03-01

    Visible and near-IR reflectivity, Moessbauer, and X ray diffraction data were obtained on powders of impact melt rock from the Manicouagan Impact Crater located in Quebec, Canada. The iron mineralogy is dominated by pyroxene for the least oxidized samples and by hematite for the most oxidized samples. Phyllosilicate (smectite) contents up to approximately 15 wt % were found in some heavily oxidized samples. Nanophase hematite and/or paramagnetic ferric iron is observed in all samples. No hydrous ferric oxides (e.g., goethite, lepidocrocite, and ferrihydrite) were detected, which implies the alteration occurred above 250 C. Oxidative alteration is thought to have occurred predominantly during late-stage crystallization and subsolidus cooling of the impact melt by invasion of oxidizing vapors and/or solutions while the impact melt rocks were still hot. The near-IR band minimum correlated with the extent of aleration Fe(3+)/Fetot and ranged from approximately 1000 nm (high-Ca pyroxene) to approximately 850 nm (bulk, well-crystalline hematite) for least and most oxidized samples, respectively. Intermediate band positions (900-920 nm) are attributed to low-Ca pyroxene and/or a composite band from hematite-pyroxene assemblages. Manicouagan data are consistent with previous assignments of hematite and pyroxene to the approximately 850 and approximately 1000nm bands observed in Martian reflectivity spectra. Manicouagan data also show that possible assignments for intermediate band positions (900-920 nm) in Martian spectra are pyroxene and/or hematite-pyroxene assemblages. By analogy with impact melt sheets and in agreement with observables for Mars, oxidative alteration of Martian impact melt sheets above 250 C and subsequent erosion could produce rocks and soils with variable proportions of hematite (both bulk and nanophase), pyroxene, and phyllosilicates as iron-bearing mineralogies. If this process is dominant, these phases on Mars were formed rapidly at relativly high temperatures on a sporadic basis throughout the history of the planet. The Manicouagan samples also show that this mineralogical diversity can be accomplished at constant chemical composition, which is also indicated for Mars from the analyses of soil at the two Viking landing sites.

  10. Hydrolysis of ferric chloride in solution

    SciTech Connect

    Lussiez, G.; Beckstead, L.

    1996-11-01

    The Detox{trademark} process uses concentrated ferric chloride and small amounts of catalysts to oxidize organic compounds. It is under consideration for oxidizing transuranic organic wastes. Although the solution is reused extensively, at some point it will reach the acceptable limit of radioactivity or maximum solubility of the radioisotopes. This solution could be cemented, but the volume would be increased substantially because of the poor compatibility of chlorides and cement. A process has been developed that recovers the chloride ions as HCl and either minimizes the volume of radioactive waste or permits recycling of the radioactive chlorides. The process involves a two-step hydrolysis at atmospheric pressure, or preferably under a slight vacuum, and relatively low temperature, about 200{degrees}C. During the first step of the process, hydrolysis occurs according to the reaction below: FeCl{sub 3 liquid} + H{sub 2}O {r_arrow} FeOCl{sub solid} + 2 HCl{sub gas} During the second step, the hot, solid, iron oxychloride is sprayed with water or placed in contact with steam, and hydrolysis proceeds to the iron oxide according to the following reaction: 2 FeOCl{sub solid} + H{sub 2}O {r_arrow} Fe{sub 2}O{sub 3 solid} + 2 HCl{sub gas}. The iron oxide, which contains radioisotopes, can then be disposed of by cementation or encapsulation. Alternately, these chlorides can be washed off of the solids and can then either be recycled or disposed of in some other way.

  11. Recovery of scrap iron metal value using biogenerated ferric iron.

    PubMed

    Ballor, Nicholas R; Nesbitt, Carl C; Lueking, Donald R

    2006-04-20

    The utility of employing biogenerated ferric iron as an oxidant for the recycling of scrap metal has been demonstrated using continuously growing cells of the extremophilic organism Acidithiobacillus ferrooxidans. A ferric iron rich (70 mol%) lixiviant resulting from bioreactor based growth of A. ferrooxidans readily solubilized target scrap metal with the resultant generation of a leachate containing elevated ferrous iron levels and solubilized copper previously resident in the scrap metal. Recovery of the copper value was easily accomplished via a cementation reaction and the clarified leachate containing a replenished level of ferrous iron as growth substrate was shown to support the growth of A. ferrooxidans and be fully recyclable. The described process for scrap metal recycling and copper recovery was shown to be efficient and economically attractive. Additionally, the utility of employing the E(h) of the growth medium as a means for monitoring fluctuations in cell density in cultures of A. ferrooxidans is demonstrated. PMID:16440341

  12. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...O, CAS Reg. No. 10045-86-0) is an odorless, yellowish-white to buff-colored powder and contains from one to four molecules of water of hydration. It is prepared by reaction of sodium phosphate with ferric chloride or ferric citrate....

  13. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...O, CAS Reg. No. 10045-86-0) is an odorless, yellowish-white to buff-colored powder and contains from one to four molecules of water of hydration. It is prepared by reaction of sodium phosphate with ferric chloride or ferric citrate....

  14. Sonochemical Deposition and Characterization of Nanophasic Amorphous Nickel on Silica Microspheres

    E-print Network

    Prozorov, Ruslan

    Sonochemical Deposition and Characterization of Nanophasic Amorphous Nickel on Silica Microspheres microspheres has not been ex- ploited so far. The major advantage of the sonochemical method, apart from

  15. Ferric-transferrin and ferric-transferrin-anion complexes: formation and characterization.

    E-print Network

    Schlabach, Michael Ray

    1974-01-01

    FERRIC-TRANSFERRIN AND FFRRIC-TRANSFERRIN-ANION COMPLEXES'. FORMATION AND CHARACTERIZATION A Thesis by MICHAEL RAY SCHLABACH Submitted to the Graduate College of Texas A & M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE December 1974 Major Subject: Biochemistry FERRIC ? TRANSFERRIN AND FERRIC-TRANSFERRIN-ANION COMPLEXES: FORMATION AND CHARACTERIZATION A Thesis MICHAEL RAY SCHLABACH Approved as to style snd content by: (' Chai of Committee) (He...

  16. Nanophase Nickel-Zirconium Alloys for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram; Whitacre, jay; Valdez, Thomas

    2008-01-01

    Nanophase nickel-zirconium alloys have been investigated for use as electrically conductive coatings and catalyst supports in fuel cells. Heretofore, noble metals have been used because they resist corrosion in the harsh, acidic fuel cell interior environments. However, the high cost of noble metals has prompted a search for less-costly substitutes. Nickel-zirconium alloys belong to a class of base metal alloys formed from transition elements of widely different d-electron configurations. These alloys generally exhibit unique physical, chemical, and metallurgical properties that can include corrosion resistance. Inasmuch as corrosion is accelerated by free-energy differences between bulk material and grain boundaries, it was conjectured that amorphous (glassy) and nanophase forms of these alloys could offer the desired corrosion resistance. For experiments to test the conjecture, thin alloy films containing various proportions of nickel and zirconium were deposited by magnetron and radiofrequency co-sputtering of nickel and zirconium. The results of x-ray diffraction studies of the deposited films suggested that the films had a nanophase and nearly amorphous character.

  17. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ferrocyanide shall...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

  18. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ferrocyanide shall...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

  19. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron (III) chloride...o)(12) of this chapter, with no limitation other than current good manufacturing practice. (d) Prior sanctions for...

  20. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron (III) chloride...o)(12) of this chapter, with no limitation other than current good manufacturing practice. (d) Prior sanctions for...

  1. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron (III) chloride...o)(12) of this chapter, with no limitation other than current good manufacturing practice. (d) Prior sanctions for...

  2. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron (III) chloride...o)(12) of this chapter, with no limitation other than current good manufacturing practice. (d) Prior sanctions for...

  3. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2299 Ferric ferrocyanide. (a...ferrocyanide is safe for use in coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in amounts...

  4. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2299 Ferric ferrocyanide. (a...ferrocyanide is safe for use in coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in amounts...

  5. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2299 Ferric ferrocyanide. (a...ferrocyanide is safe for use in coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in amounts...

  6. SO2 removal with ferric sulfate solution.

    PubMed

    Jiang, J-H; Yan, H; Li, Y-H; Xie, W-J; Li, L-H; Cai, W-M

    2008-04-01

    The determination of the influence of the concentration of ferric sulfate solution on SO2 absorption was performed in this study. It was found that the SO2 absorption efficiency increased with increasing ferric concentration, and decreased with the acidity of the spraying solution. As the hydrolysis of ferric ions occurs in solution, the SO2 removal efficiency increased slowly with increasing Fe(III) concentration. Taking into account the hydrodynamic and mass transfer characteristics of the packed column, the enhancement factor (E) was found to depend on the concentration of the ferric ions and pH, which indicated that it could be used for the simulation or design of SO2 scrubbers. PMID:18619149

  7. Increased osteoblast functions on nanophase titania dispersed in poly-lactic-co-glycolic acid composites

    NASA Astrophysics Data System (ADS)

    Liu, Huinan; Slamovich, Elliott B.; Webster, Thomas J.

    2005-07-01

    The design of nanophase titania/poly-lactic-co-glycolic acid (PLGA) composites offers an exciting approach to combine the advantages of a degradable polymer with nano-size ceramic grains to optimize physical and biological properties for bone regeneration. Importantly, nanophase titania mimics the size scale of constituent components of bone since it is a nanostructured composite composed of nanometre dimensioned hydroxyapatite well dispersed in a mostly collagen matrix. For these reasons, the objective of the present in vitro study was to investigate osteoblast (bone-forming cell) adhesion and long-term functions on nanophase titania/PLGA composites. Since nanophase titania tended to significantly agglomerate when added to polymers, different sonication output powers were applied in this study to improve titania dispersion. Results demonstrated that the dispersion of titania in PLGA was enhanced by increasing the intensity of sonication and that greater osteoblast adhesion correlated with improved nanophase titania dispersion in PLGA. Moreover, results correlated better osteoblast long-term functions, such as alkaline phosphatase activity and calcium-containing mineral deposition, on nanophase titania/PLGA composites compared to plain PLGA. In fact, the greatest collagen production by osteoblasts occurred when cultured on nanophase titania sonicated in PLGA at the highest powers. In this manner, the present study demonstrates that PLGA composites with well dispersed nanophase titania can enhance osteoblast functions necessary for improved bone tissue engineering applications.

  8. New nanophase iron-based catalysts for hydrocracking applications

    SciTech Connect

    Matson, D.W.; Linehan, J.C.; Darab, J.G.; Camaioni, D.M.; Autrey, S.T.; Lui, E.

    1994-11-01

    Development of highly efficient iron-based materials for processes involving carbon-carbon bond cleavage, including petroleum hydrocracking and coal liquefaction, offers the potential for decreasing catalyst costs as well as reducing the need for expensive catalyst recovery and recycling steps. Carbon-carbon bond cleavage catalysts produced in situ at reaction conditions from nanocrystalline hydrated iron oxides, show high activity and selectivity in model compound studies. Two highly active catalyst precursors, ferric oxyhydroxysulfate (OHS) and 6-line ferrihydrite, can be produced by a flow-through hydrothermal powder synthesis method, the Rapid Thermal Decomposition of precursors in Solution (RTDS) process. Model compound studies indicate that both catalyst precursors are active at a 400 C reaction temperature, but that there are significant differences in their catalytic characteristics. The activity of 6-line ferrihydrite is highly dependent on the particle (aggregate) size whereas the activity of the OHS is essentially independent of particle size. These differences are attributed to variations in the crystallite aggregation and particle surface characteristics of the two catalyst precursor materials. Catalytic activity is retained to lower reaction temperatures in tests using OHS than in similar tests using 6-line ferrihydrite.

  9. The leaching of chalcopyrite with ferric sulfate

    NASA Astrophysics Data System (ADS)

    Hirato, Tetsuji; Majima, Hiroshi; Awakura, Yasuhiro

    1987-09-01

    The leaching kinetics of natural chalcopyrite crystals with ferric sulfate was studied. The morphology of the leached chalcopyrite and the electrochemical properties of chalcopyrite electrodes also were investigated. The leaching of chalcopyrite showed parabolic-like kinetics initially and then showed linear kinetics. In the initial stage, a dense sulfur layer formed on the chalcopyrite surface. The growth of the layer caused it to peel from the surface, leaving a rough surface. In the linear stage, no thick sulfur layer was observed. In this investigation, chalcopyrite leaching in the linear stage was principally studied. The apparent activation energy for chalcopyrite leaching was found to range from 76.8 to 87.7 kJ mol-1, and this suggests that the leaching of chalcopyrite is chemically controlled. The leaching rate of chalcopyrite increases with an increase in Fe(SO4)1.5 concentration up to 0.1 mol dm-3, but a further increase of the Fe(SO4)1.5 concentration has little effect on the leaching rate. The dependency of the mixed potential upon Fe(SO4)1.5 concentration was found to be 79 mV decade-1 from 0.01 mol dm-3 to 1 mol dm-3 Fe(SO4)1.5. Both the leaching rate and the mixed potential decreased with an increased FeSO4 concentration. The anodic current of Fe(II) oxidation on the chalcopyrite surface in a sulfate medium was larger than that in a chloride medium.

  10. Ferric chloride graphite intercalation compounds prepared from graphite fluoride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1994-01-01

    The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400 C. The graphite fluorides used for this reaction have an sp3 electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in the presence of air. The ferric chloride does not have to be predried. The products have an sp2 electronic structure and are electrical conductors. They contain first stage FeCl3 intercalated graphite. Some of the products contain FeCl2*2H2O, others contain FeF3 in concentrations that depend on the intercalation condition. The graphite intercalated compounds (GIC) deintercalated slowly in air at room temperature, but deintercalated quickly and completely at 370 C. Deintercalation is accompanied by the disappearing of iron halides and the formation of rust (hematite) distributed unevenly on the fiber surface. When heated to 400 C in pure N2 (99.99 vol %), this new GIC deintercalates without losing its molecular structure. However, when the compounds are heated to 800 C in quartz tube, they lost most of its halogen atoms and formed iron oxides (other than hematite), distributed evenly in or on the fiber. This iron-oxide-covered fiber may be useful in making carbon-fiber/ceramic-matrix composites with strong bonding at the fiber-ceramic interface.

  11. Iron metabolism in aerobes: managing ferric iron hydrolysis and ferrous iron autoxidation

    PubMed Central

    Kosman, Daniel J.

    2012-01-01

    Aerobes and anaerobes alike express a plethora of essential iron enzymes; in the resting state, the iron atom(s) in these proteins are in the ferrous state. For aerobes, ferric iron is the predominant environmental valence form which, given ferric iron’s aqueous chemistry, occurs as ‘rust’, insoluble, bio-inert polymeric ferric oxide that results from the hydrolysis of [Fe(H2O)6]3+. Mobilizing this iron requires bio-ferrireduction which in turn requires managing the rapid autoxidation of the resulting FeII which occurs at pH > 6. This review examines the aqueous redox chemistry of iron and the mechanisms evolved in aerobes to suppress the ‘rusting out’ of FeIII and the ROS-generating autoxidation of FeII so as to make this metal ion available as the most ubiquitous prosthetic group in metallobiology. PMID:23264695

  12. Formation of ferric iron crusts in Quaternary sediments of Lake Baikal, Russia, and implications for paleoclimate

    Microsoft Academic Search

    R. G. Deike; L. Granina; E. Callender; J. J. McGee

    1997-01-01

    Phosphate-bearing, ferric iron and siliceous crusts ranging in age from Recent to approximately 65,000 yr B.P. are observed in sediments of Lake Baikal. In younger sediments the crusts are at the base of a spectrum of secondary iron and manganese oxides that accumulate near the sediment\\/water interface in the zone of positive oxidation potential beneath an oxygenated water column. In

  13. Ferric leaching of copper slag flotation tailings

    Microsoft Academic Search

    F. Carranza; N. Iglesias; A. Mazuelos; R. Romero; O. Forcat

    2009-01-01

    The pyrometallurgical production of copper generates slags, a residue with a significant content of this metal. Copper can be recovered from the slags by froth flotation after cooling, crushing, and grinding. The obtained Cu-concentrate is sent to the pyrometallurgical process. If grinding is not fine enough for efficient flotation, copper is lost in tailings. In this paper, the ferric leaching

  14. Arsenic Removal from Groundwater using Ferric

    Microsoft Academic Search

    R. G. Fernandez; B. Petrusevski

    Arsenic is a carcinogenic metalloid that is currently regulated in drinking water. The levels of arsenic in finished water in an existing water treatment plant are exceeding the current regulation of 10 µg\\/L. One of the available technologies for arsenic removal from groundwater is adsorption onto coagulated flocs and in this field, ferric chloride is the most commonly used coagulant

  15. The Presence of Nanophase Al-Si-Fe Components at Mawrth Vallis Indicate Varying Environmental Conditions

    NASA Astrophysics Data System (ADS)

    Bishop, J. L.; Rampe, E. B.

    2014-07-01

    The presence of nanophase allophane, opal and Fe-rich material at Mawrth Vallis together with multiple phyllosilicates indicate varying environmental conditions over time and also suggests regionally different aqueous environments.

  16. Increased osteoblast functions on nanophase titania dispersed in poly-lactic-co-glycolic acid composites

    Microsoft Academic Search

    Huinan Liu; Elliott B. Slamovich; Thomas J. Webster

    2005-01-01

    The design of nanophase titania\\/poly-lactic-co-glycolic acid (PLGA) composites offers an exciting approach to combine the advantages of a degradable polymer with nano-size ceramic grains to optimize physical and biological properties for bone regeneration. Importantly, nanophase titania mimics the size scale of constituent components of bone since it is a nanostructured composite composed of nanometre dimensioned hydroxyapatite well dispersed in a

  17. Plasma membrane ferric reductase activity of iron-limited algal cells is inhibited by ferric chelators.

    PubMed

    Sonier, Mathew B; Weger, Harold G

    2010-12-01

    Iron-limited cells of the green alga Chlorella kesslerii use a reductive mechanism to acquire Fe(III) from the extracellular environment, in which a plasma membrane ferric reductase reduces Fe(III)-chelates to Fe(II), which is subsequently taken up by the cell. Previous work has demonstrated that synthetic chelators both support ferric reductase activity (when supplied as Fe(III)-chelates) and inhibit ferric reductase. In the present set of experiments we extend these observations to naturally-occurring chelators and their analogues (desferrioxamine B mesylate, schizokinen, two forms of dihydroxybenzoic acid) and also two formulations of the commonly-used herbicide N-(phoshonomethyl)glycine (glyphosate). The ferric forms of the larger siderophores (desferrioxamine B mesylate, schizokinen) and Fe(III)-N-(phoshonomethyl)glycine (as the isopropylamine salt) all supported rapid rates of ferric reductase activity, while the iron-free forms inhibited reductase activity. The smaller siderophores/siderophore precursors, 2,3- and 3,4-dihydroxybenzoic acids, did not support high rates of reductase in the ferric form but did inhibit reductase activity in the iron-free form. Bioassays indicated that Fe(III)-chelates that supported high rates of ferric reductase activity also supported a large stimulation in the growth of iron-limited cells, and that an excess of iron-free chelator decreased the growth rate. With respect to N-(phosphonomethyl)glycine, there were differences between the pure compound (free acid form) and the most common commercial formulation (which also contains isopropylamine) in terms of supporting and inhibiting ferric reductase activity and growth. Overall, these results suggest that photosynthetic organisms that use a reductive strategy for iron acquisition both require, and are potentially simultaneously inhibited by, ferric chelators. Furthermore, these results also may provide an explanation for the frequently contradictory results of N-(phosphonomethyl)glycine application to crops: we suggest that low concentrations of this molecule likely solubilize Fe(III), making it available for plant growth, but that higher (but sub-lethal) concentrations decrease iron acquisition by inhibiting ferric reductase activity. PMID:20508972

  18. Understanding Arsenate Reaction Kinetics with Ferric Hydroxides

    PubMed Central

    Farrell, James; Chaudhary, Binod K.

    2015-01-01

    Understanding arsenic reactions with ferric hydroxides is important in understanding arsenic transport in the environment and in designing systems for removing arsenic from potable water. Many experimental studies have shown that the kinetics of arsenic adsorption on ferric hydroxides is biphasic, where a fraction of the arsenic adsorption occurs on a time scale of seconds while full equilibrium may require weeks to attain. This research employed density functional theory modeling in order to understand the mechanisms contributing to biphasic arsenic adsorption kinetics. The reaction energies and activation barriers for three modes of arsenate adsorption to ferric hydroxides were calculated. Gibbs free energies of reaction depended on the net charge of the complexes, which is a function of the system pH value. Physical adsorption of arsenate to ferric hydroxide proceeded with no activation barrier, with Gibbs free energies of reaction ranging from ?21 to ?58 kJ/mol. The highest Gibbs free energies of reaction for physical adsorption resulted from negative charge assisted hydrogen bonding between H atoms on the ferric hydroxide and O atoms in arsenate. The conversion of physically adsorbed arsenate into monodentate surface complexes had Gibbs free energies of activation ranging from 62 to 73 kJ/mol, and Gibbs free energies of reaction ranging from ?23 to ?38 kJ/mol. The conversion of monodentate surface complexes to bidentate, binuclear complexes had Gibbs free energies of activation ranging from 79 to 112 kJ/mol, and Gibbs free energies of reaction ranging from ?11 to ?55 kJ/mol. For release of arsenate from uncharged bidentate complexes, energies of activation as high as 167 kJ/mol were encountered. Increasingly negative charges on the complexes lowered the activation barriers for desorption of arsenate, and in complexes with ?2 charges, the highest activation barrier was 65 kJ/mol. This study shows that the slow kinetics associated with arsenic adsorption and desorption can be attributed to the high Gibbs free energies of activation for forming and breaking bonds with the ferric hydroxide. PMID:23806140

  19. Chemical oxidation kinetics of pyrite in bioleaching processes

    Microsoft Academic Search

    M Boon; J. J Heijnen

    1998-01-01

    Bio-oxidation experiments with Leptospirillum bacteria were used to determine the chemical oxidation kinetics of pyrite in acidic ferric sulphate solutions (0.1–0.2 M) at 30°C and pH 1.6. The proposed method is applicable because the oxidation of pyrite with Leptospirillum bacteria consists of two sub-processes: (i) Pyrite is chemically oxidized with ferric iron to sulphate and ferrous iron, (ii) Ferric iron

  20. Intravenous ferric carboxymaltose for anaemia in pregnancy

    PubMed Central

    2014-01-01

    Background Iron deficiency is a common nutritional deficiency amongst women of childbearing age. Peri-partum iron deficiency anaemia (IDA) is associated with significant maternal, fetal and infant morbidity. Current options for treatment are limited: these include oral iron supplementation, which can be ineffective and poorly tolerated, and red blood cell transfusions, which carry an inherent risk and should be avoided. Ferric carboxymaltose is a new treatment option that may be better tolerated. The study was designed to assess the safety and efficacy of iron deficiency anaemia (IDA) correction with intravenous ferric carboxymaltose in pregnant women with mild, moderate and severe anaemia in the second and third trimester. Methods Prospective observational study; 65 anaemic pregnant women received ferric carboxymaltose up to 15 mg/kg between 24 and 40 weeks of pregnancy (median 35 weeks gestational age, SD 3.6). Treatment effectiveness was assessed by repeat haemoglobin (Hb) measurements and patient report of well-being in the postpartum period. Safety was assessed by analysis of adverse drug reactions and fetal heart rate monitoring during the infusion. Results Intravenous ferric carboxymaltose infusion significantly increased Hb values (p?ferric carboxymaltose in the treatment of iron deficiency anaemia in pregnancy. PMID:24667031

  1. Ordered zinc-vacancy induced Zn0.75Ox nanophase structure Yong Ding, Rusen Yang, Zhong Lin Wang *

    E-print Network

    Wang, Zhong L.

    Ordered zinc-vacancy induced Zn0.75Ox nanophase structure Yong Ding, Rusen Yang, Zhong Lin Wang, GA 30332-0245, USA Received 24 February 2006; accepted 24 March 2006 by J.W.P. Hsu Available online 18 April 2006 Abstract Using transmission electron microscopy, a new nano-phase structure of Zn0.75Ox

  2. The reactions of a dinuclear ferric complex (oxo) di-iron(III) triethylenetetraamminehexaacetate, Fe 2O(ttha) 2-, with oxidizing and reducing free radicals. A pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Rush, James D.; Cabelli, Diane E.

    1997-06-01

    The rate constants at which oxidizing and reducing radicals react with the dinuclear iron(III) complex Fe 2O(ttha) 2- were measured in neutral aqueous solution. The rate constants for reduction of the complex by ·CO 2.- CH 3.CHOH and O 2.- were found to be comparable with rate constants previously measured in mononuclear iron(III) polyaminocarboxylate systems. Fe 2O(ttha) 2- reacts slowly with O 2.- ( k8 = (1.2 ± 0.2) × 10 4 dm 3 mol -1 s -1) and, hence, is a relatively poor catalyst for the dismutation of superoxide radical. The hydrated electron reduces the complex at a diffusion-controlled rate in a process which consumes one proton: e aq- + Fe 2O(ttha) 2- ? Fe 2III,IIO(ttha) 3- The reduction by carbon-centered radicals produces a (III,II) mixed-valence complex with an absorption spectrum different from that of the Fe 2(II,III) species produced from reduction by the hydrated electron. The oxidizing radicals .OH and ·CO 3- appear to act as reductants of the complex via ligand oxidation rather than by oxidation of the Fe 2IIIO core to Fe 2III,IVO. In the former case ligand attack appears to occur mainly at the methylene carbon of a glycinate group. The decarboxylation product, CO 2, was detected by its aquation reaction in the presence of a pH sensitive dye, bromthymol blue.

  3. Energy Transduction by Anaerobic Ferric Iron Respiration in Thiobacillus ferrooxidans

    Microsoft Academic Search

    J. T. Pronk; K. Liem; P. Bos; J. G. Kuenen

    1991-01-01

    Formate-grown cells of the obligately chemolithoautotrophic acidophile Thiobacillus ferrooxidans were capable of formate- and elemental sulfur-dependent reduction of ferric iron under anaerovic conditions. Under aerobic conditions, both oxygen and ferric iron could be simultaneously used as electron acceptors. To investigate whether anaerobic ferric iron respiration by T. ferrooxidans is an energy-transducing process, uptake of amino acids was studied. Glycine uptake

  4. Ferric carboxymaltose: a review of its use in iron deficiency.

    PubMed

    Keating, Gillian M

    2015-01-01

    Ferric carboxymaltose (Ferinject(®), Injectafer(®)) is an intravenous iron preparation approved in numerous countries for the treatment of iron deficiency. A single high dose of ferric carboxymaltose (up to 750 mg of iron in the US and 1,000 mg of iron in the EU) can be infused in a short time frame (15 min). Consequently, fewer doses of ferric carboxymaltose may be needed to replenish iron stores compared with some other intravenous iron preparations (e.g. iron sucrose). Ferric carboxymaltose improved self-reported patient global assessment, New York Heart Association functional class and exercise capacity in patients with chronic heart failure and iron deficiency in two randomized, placebo-controlled trials (FAIR-HF and CONFIRM-HF). In other randomized controlled trials, ferric carboxymaltose replenished iron stores and corrected anaemia in various populations with iron-deficiency anaemia, including patients with chronic kidney disease, inflammatory bowel disease or heavy uterine bleeding, postpartum iron-deficiency anaemia and perioperative anaemia. Intravenous ferric carboxymaltose was generally well tolerated, with a low risk of hypersensitivity reactions. It was generally better tolerated than oral ferrous sulfate, mainly reflecting a lower incidence of gastrointestinal adverse effects. The most common laboratory abnormality seen in ferric carboxymaltose recipients was transient, asymptomatic hypophosphataemia. The higher acquisition cost of ferric carboxymaltose appeared to be offset by lower costs for other items, with the potential for cost savings. In conclusion, ferric carboxymaltose is an important option for the treatment of iron deficiency. PMID:25428711

  5. Coordination modes of tyrosinate-ligated catalase-type heme enzymes: Magnetic circular dichroism studies of Plexaura homomalla allene oxide synthase, Mycobacterium avium ssp . Paratuberculosis protein-2744c, and bovine liver catalase in their ferric and ferrous states

    Microsoft Academic Search

    D. M. Indika Bandara; Masanori Sono; Grant S. Bruce; Alan R. Brash; John H. Dawson

    Bovine liver catalase (BLC), catalase-related allene oxide synthase (cAOS) from Plexaura homomalla, and a recently isolated protein from the cattle pathogen Mycobacterium avium ssp. paratuberculosis (MAP-2744c (MAP)) are all tyrosinate-ligated heme enzymes whose crystal structures have been reported. cAOS and MAP have low (<20%) sequence similarity to, and significantly different catalytic functions from, BLC. cAOS transforms 8R-hydroperoxy-eicosatetraenoic acid to an

  6. Synthesis of the NiZr 2 intermetallic compound nanophase materials

    NASA Astrophysics Data System (ADS)

    K., Lu; D. Liu, X.; H. Yuan, F.

    1996-02-01

    The NiZr 2 intermetallic compound nanocrystalline materials were synthesized by completely crystallizing an amorphous NiZr 2 alloy under proper annealing conditions. The microstructure of the NiZr 2 nanophase was characterized by means of transmission electron microscopy (TEM), high resolution electron microscopy (HREM), and X-ray diffraction (XRD), respectively. It was found that the NiZr 2 nanophase sample consists of ultrafine lamellae with thicknesses of a few nanometers and there are well-defined twin boundaries between the neighboring lamellae. The dependence of the annealing temperature on the mean grain size was determined. The formation process of the NiZr 2 nanophase during a polymorphous crystallization of the amorphous phase was monitored by a differential scanning calorimeter (DSC) and its kinetics was analyzed.

  7. Nanophase materials assembled from atom clusters. [Average grain/structural domain sizes <100 nm--review

    SciTech Connect

    Siegel, R.W.

    1992-12-01

    Nanometer-scale atom clusters (with average diameters below 20 nm) of a variety of materials, including both metals and ceramics, have been synthesized by precursor evaporation and condensation in high-purity gases. The gas-entrained clusters can be collected and subsequently consolidated in situ under ultrahigh vacuum or other controlled atmosphere conditions to create bulk nanophase materials. These ultrafine-grained materials have properties that are often significantly different and considerably improved relative to those of their coarser-grained counterparts. The observed property changes relate to both their small grain sizes and the large percentage of their atoms in grain boundary environments. Since it is becoming apparent that their properties can be engineered during gas-phase synthesis and subsequent processing, nanophase materials assembled from atom clusters should have significant potential for technological development in a variety of applications. Some of the recent research on nanophase materials is reviewed.

  8. Cupric and ferric ions inactivate HIV.

    PubMed

    Sagripanti, J L; Lightfoote, M M

    1996-03-01

    Human immunodeficiency virus (HIV-1) was inactivated by either cupric or ferric ions when the virus was free in solution and also 3 hr after cell infection. Fifty percent inactivation of cell-free HIV was achieved with Cu(II) at a concentration between 0.16 and 1.6 mM, or by 1.8 to 18 mM Fe(III). Thus, the dose to inactivate 50% of infectious HIV (D50) by Cu(II) or Fe(III) is higher than that reported for glutaraldehyde (0.1 mM); between the D50 reported for sodium hypochlorite (1.3 mM) and sodium hydroxide (11.5 mM), and significantly lower than that required for HIV inactivation by ethanol (360 mM). Treatment of infected cells for 30 min at 20 degrees C with 6 mM Cu(II) or Fe(III) completely inhibited the formation of syncytia and the synthesis of virus-specific p24 antigen in HIV-infected cells, while still preserving cell viability. The virucidal properties of cupric and ferric ions could be exploited for the development of novel virucidal formulations efficient against HIV. PMID:8906994

  9. Ferric iron budget of Kaapvaal cratonic mantle peridotite

    NASA Astrophysics Data System (ADS)

    Woodland, A.

    2012-04-01

    Oxidation fugacity plays an important role in many geochemical processes, such as partial melting and melt-rock interaction. How mantle peridotite responds during such processes is dependent on the amount of Fe2O3 present, since it occurs in much smaller quantities than Fe2+ and affects buffering capacity. This is particularly the case since redox reactions have been directly implicated in the rejuvenation and eventual breakup of cratons (e.g. Foley 2008, 2011). In addition, oxygen fugacity also influences the incorporation of OH in nominally anhydrous minerals, which can affect the mechanical integrity of cratonic blocks (Peslier et al. 2010). These issues are important for understanding the evolution of the upper mantle beneath the Kaapvaal craton. Canil and coworkers (1994, 1996) reported bulk ferric iron contents for 11 peridotites (10 garnet-bearing and 1 spinel-bearing) from the Kaapvaal. The purpose of this study is to build on their pioneering work to better assess the ferric iron budget of Kaapvaal cratonic mantle and to improve our understanding of how ferric iron is distributed within the peridotitic assemblage. Our data set includes more than 30 additional samples, predominantly garnet peridoites, from 7 localities in South Africa and Lesotho. Bulk Fe2O3 contents were determined by combining measured Fe3+ contents of individual minerals (by Mössbauer spectroscopy) with their respective modal proportion in each sample. Fe3+ contents of garnet and clinopyroxene reported in Woodland & Koch (2003), Lazarov et al. (2009) and Woodland (2009) were combined with new data for orthopyroxene (opx) and modal mineralogy to make this assessment. Opx has Fe3+/Fetot of 0.04-0.1 and Fe3+ contents are comparable between Opx and coexisting Cpx. Calculated whole rock Fe2O3 contents range from 0.02 to 0.29 wt % with contents systematically decreasing with increasing degrees of depletion (as indicated by increasing MgO and decreasing Al2O3 content). For a given MgO content spinel peridotites from younger mantle tend to have even lower Fe2O3 contents (Woodland et al. 2006), suggesting that the cratonic mantle has been somewhat re-enriched in Fe3+ through subsequent metasomatic processes. Variable degrees of metasomatism are probably also responsible for the observed scatter in the current data set. Opx contains 40-80% of the total Fe2O3, making it the dominant contributor. This is a higher proportion than usually observed in non-cratonic spinel peridotites (Woodland et al. 2006) and can be related to the generally higher modal amounts of Opx in the Kaapvaal mantle. Garnet is the second most important carrier of Fe3+. Although Cpx has the highest Fe3+/Fetot of all phases, its low total Fe content and low modal proportion means that it makes a relatively small contribution to the overall Fe2O3 budget. No correlation between whole rock Fe2O3 content and calculated oxygen fugacity is apparent, due to variations in modal mineralogy between the samples. Canil D, O'Neill HStC (1996) Distribution of ferric iron in some upper-mantle assemblages. J. Petrol. 37, 609-635. Canil D, O'Neill HStC, Pearson DG, Rudnick R, McDonough WF, Carswell, DA (1994) Ferric iron in peridotites and mantle oxidation states. Earth Planet Sci Lett 123, 205-220. Foley SF (2008) Rejuvenation and erosion of the cratonic lithosphere. Nature Geoscience 1, 503-510. Foley SF (2011) A reappraisal of redox melting in the Earth's mantle as a function of tectonic setting and time. J Petrol, 52,1363-1391. Lazarov, M, Woodland, AB, Brey, GP (2009) Thermal state and redox conditions of the Kaapvaal mantle: A study of xenoliths from the Finsch mine, South Africa. Lithos 112 (S2), 913-923 Peslier AH, Woodland AB, Bell DR, Lazarov M (2010) Olivine water contents in the continental lithosphere and the longevity of cratons. Nature, doi:10.1038/nature09317. Woodland AB (2009) Ferric iron contents of clinopyroxene from cratonic mantle and partitioning behaviour with garnet. Lithos, 112S,1143-1149. Woodland AB, Koch M (2003) Variation in oxygen fugacity with depth in the upper man

  10. Statistics of sub-Poissonian nucleation in a nanophase

    NASA Astrophysics Data System (ADS)

    Glas, Frank

    2014-09-01

    We develop a fully analytical calculation of the sub-Poissonian statistics resulting from the temporal anticorrelation of the nucleation events in a supersaturated nanophase, such as occurs in particular during vapor-liquid-solid growth of nanowires [F. Glas, J. C. Harmand, and G. Patriarche, Phys. Rev. Lett. 104, 135501 (2010), 10.1103/PhysRevLett.104.135501]. The sequence of nucleation events is modeled as a stochastic Markov process. The deviation from Poisson statistics is quantified by a single parameter ?, namely the ratio of the nucleation probabilities immediately after and before nucleation. We first determine self-consistently, by using q-calculus, the densities of probability of the nucleation probability, both when nucleation occurs and at an arbitrary instant. We then derive the probability for having a given number of nucleations in any given time interval. The distribution of these probabilities shows a marked narrowing with respect to Poisson statistics, in agreement with our previous experiments. We calculate explicitly the standard deviation of this distribution, which quickly saturates as the length of the time interval increases. Finally, we compute the distribution of the waiting times between nucleations. We discuss how the computed quantities vary with parameter ?. The results are in complete agreement with our numerical simulations. Somewhat surprisingly, a marked narrowing of the distribution of the numbers of nucleations occurring in fixed time intervals appears as fully compatible with a very broad distribution of waiting times.

  11. Iron absorption of ferric glycinate is controlled by iron stores

    Microsoft Academic Search

    Fernando Pizarro; Raúl Uicich; Manuel Olivares; Carlos Almeida; Mará L. Díaz; Esteban Carmuega; Alejandro O'Donnell; Mirta E Valencia

    1998-01-01

    Ferric glycinate bioavailability and its absorption control by iron stores was assessed by radioisotopic studies in 30 subjects (17 women and 13 men), in apparent good health, of normal iron status and of high socioeconomic level. Absorption studies used ferric glycinate labeled intrinsically during the synthesis process of this compound as a tracer. In two groups of 15 subjects, iron

  12. Separate pathways for cellular uptake of ferric and ferrous iron.

    PubMed

    Conrad, M E; Umbreit, J N; Moore, E G; Hainsworth, L N; Porubcin, M; Simovich, M J; Nakada, M T; Dolan, K; Garrick, M D

    2000-10-01

    Separate pathways for transport of nontransferrin ferric and ferrous iron into tissue cultured cells were demonstrated. Neither the ferric nor ferrous pathway was shared with either zinc or copper. Manganese shared the ferrous pathway but had no effect on cellular uptake of ferric iron. We postulate that ferric iron was transported into cells via beta(3)-integrin and mobilferrin (IMP), whereas ferrous iron uptake was facilitated by divalent metal transporter-1 (DMT-1; Nramp-2). These conclusions were documented by competitive inhibition studies, utilization of a beta(3)-integrin antibody that blocked uptake of ferric but not ferrous iron, development of an anti-DMT-1 antibody that blocked ferrous iron and manganese uptake but not ferric iron, transfection of DMT-1 DNA into tissue culture cells that showed enhanced uptake of ferrous iron and manganese but neither ferric iron nor zinc, hepatic metal concentrations in mk mice showing decreased iron and manganese but not zinc or copper, and data showing that the addition of reducing agents to tissue culture media altered iron binding to proteins of the IMP and DMT-1 pathways. Although these experiments show ferric and ferrous iron can enter cells via different pathways, they do not indicate which pathway is dominant in humans. PMID:11005764

  13. The leaching of nickeliferous laterite with ferric chloride

    NASA Astrophysics Data System (ADS)

    Munroe, Norman D. H.

    1997-12-01

    Several experiments were conducted to investigate the extraction of nickel from nickeliferous laterite by ferric chloride solutions as a function of pulp density, solution composition, and temperature. Solubility relationships for goethite and nickel laterite in aqueous solution were reviewed in terms of leaching rates and reaction mechanisms. Generally, the amount of nickel extracted increased with temperature, the amount of “free acid,” and ferric chloride concentration; however, the amount was inhibited by ferrous chloride. In this investigation, as much as 96 pct of the available nickel was extracted by ferric chloride solution. Nickel extraction was found to be more dependent on ferric chloride concentration than on the concentration of hydrochloric acid. Mechanistically, nickel extraction occurred by the formation of an intermediate ferric chloride complex, which was then hydrolyzed to hematite.

  14. What do we really know about the atomic-scale structures of nanophase materials?

    Microsoft Academic Search

    R. Siegel

    1994-01-01

    Robert W. Balluffi has spent a rich research lifetime critically investigating and elucidating the atomic scale defect structures of materials. Now, a new class of ultrafine-grained materials has been created in which such defects exercise a dominant role. The structures of these new nanophase materials, both metals and ceramics, have been investigated over the past several years by a wide

  15. Nanophase-Segregation and Transport in Nafion 117 from Molecular Dynamics Simulations: Effect of Monomeric Sequence

    E-print Network

    Goddard III, William A.

    Nanophase-Segregation and Transport in Nafion 117 from Molecular Dynamics Simulations: EffectVed: September 23, 2003; In Final Form: January 15, 2004 Nafion polyelectrolyte is widely used in polymer electrolyte membrane fuel cells (PEMFC) due to its high proton conductivity. The properties of hydrated Nafion

  16. Ferric chloride based downstream process for microalgae based biodiesel production.

    PubMed

    Seo, Yeong Hwan; Sung, Mina; Kim, Bohwa; Oh, You-Kwan; Kim, Dong Yeon; Han, Jong-In

    2015-04-01

    In this study, ferric chloride (FeCl3) was used to integrate downstream processes (harvesting, lipid extraction, and esterification). At concentration of 200mg/L and at pH 3, FeCl3 exhibited an expected degree of coagulation and an increase in cell density of ten times (170mg/10mL). An iron-mediated oxidation reaction, Fenton-like reaction, was used to extract lipid from the harvested biomass, and efficiency of 80% was obtained with 0.5% H2O2 at 90°C. The iron compound was also employed in the esterification step, and converted free fatty acids to fatty acid methyl esters under acidic conditions; thus, the fatal problem of saponification during esterification with alkaline catalysts was avoided, and esterification efficiency over 90% was obtained. This study clearly showed that FeCl3 in the harvesting process is beneficial in all downstream steps and have a potential to greatly reduce the production cost of microalgae-originated biodiesel. PMID:25647024

  17. Lunar mare soils: Space weathering and the major effects of surface-correlated nanophase Fe

    NASA Astrophysics Data System (ADS)

    Taylor, Lawrence A.; Pieters, Carlé M.; Keller, Lindsay P.; Morris, Richard V.; McKay, David S.

    2001-11-01

    Lunar soils form the ``ground truth'' for calibration and modeling of reflectance spectra for quantitative remote sensing. The Lunar Soil Characterization Consortium, a group of lunar sample and remote sensing scientists, has undertaken the extensive task of characterization of lunar soils, with respect to their mineralogical and chemical makeup. This endeavor is aimed at deciphering the effects of space weathering of soils from the Moon, and these results should apply to other airless bodies. Modal abundances and chemistries of minerals and glasses in the <45 ?m size fractions of nine selected mare soils have been determined, along with the bulk chemistry of each size fraction, and their IS/FeO values. These data can be addressed at http:/web.utk.edu/~pgi/data.html. As grain size decreases, the bulk composition of each size fraction continuously changes and approaches the composition of the agglutinitic glasses. Past dogma had it that the majority of the nanophase Fe0 resides in the agglutinitic glasses. However, as grain size of a soil decreases, the percentage of the total iron present as nanophase-sized Fe0 increases dramatically, while the agglutinitic glass content rises only slightly. This is evidence for a large contribution to the IS/FeO values from surface-correlated nanophase Fe0, particularly in the <10 ?m size fraction. This surficial nanophase Fe0 is present largely as vapor-deposited patinas on the surfaces of almost every particle of the mature soils. It is proposed that these vapor-deposited, nanophase Fe0-bearing patinas may have far greater effects upon reflectance spectra of mare soils than the agglutinitic Fe0.

  18. Ferric chelate reduction by suspension culture cells and roots of soybean: A kinetic comparison

    Microsoft Academic Search

    J. D. Cornett; G. V. Johnson

    1991-01-01

    The abilities of suspension cultures and intact roots of soybean (Glycine max L. cv. Hawkeye) to reduce ferric chelate were compared. Ferric chelate was supplied as ferric hydroxyethylethylenediaminetriacetic acid (FeHEDTA) and reduction was measured spectrophotometrically using bathophenan-throlinedisulfonic acid (BPDS) as the ferrous scavenger. Ferric chelate reduction by cell suspension cultures showed typical saturation kinetics; however, no difference was observed between

  19. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ammonium ferrocyanide...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

  20. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive ferric ammonium ferrocyanide...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

  1. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2298 Ferric ammonium ferrocyanide...ferrocyanide is safe for use in coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in amounts...

  2. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2298 Ferric ammonium ferrocyanide...ferrocyanide is safe for use in coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in amounts...

  3. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2298 Ferric ammonium ferrocyanide...ferrocyanide is safe for use in coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in amounts...

  4. Remediation of sulfidic wastewater by catalytic oxidation with hydrogen peroxide.

    PubMed

    Ahmad, Naveed; Maitra, Saikat; Dutta, Binay Kanti; Ahmad, Farooq

    2009-01-01

    Oxidation of sulfide in aqueous solution by hydrogen peroxide was investigated in the presence of hydrated ferric oxide catalyst. The ferric oxide catalyst was synthesized by sol gel technique from ferric chloride and ammonia. The synthesized catalyst was characterized by Fourier transform infrared spectroscopy, X-Ray diffraction analysis, scanning electrom microscope and energy dispersive X-ray analysis. The catalyst was quite effective in oxidizing the sulfide by hydrogen peroxide. The effects of sulfide concentration, catalyst loading, H2O2 dosing and temperature on the kinetics of sulfide oxidation were investigated. Kinetic equations and activation energies for the catalytic oxidation reaction were calculated based on the experimental results. PMID:20131606

  5. Nanophase Carbonates on Mars: Implications for Carbonate Formation and Habitability

    NASA Technical Reports Server (NTRS)

    Archer, P. Douglas, Jr.; Lauer, H. Vern; Ming, Douglas W.; Niles, Paul B.; Morris, Richard V.; Rampe, Elizabeth B.; Sutter, Brad

    2014-01-01

    Despite having an atmosphere composed primarily of CO2 and evidence for abundant water in the past, carbonate minerals have only been discovered in small amounts in martian dust [1], in outcrops of very limited extent [2, 3], in soils in the Northern Plains (the landing site of the 2007 Phoenix Mars Scout Mission) [4] and may have recently been detected in aeolian material and drilled and powdered sedimentary rock in Gale Crater (the Mars Science Laboratory [MSL] landing site) [5]. Thermal analysis of martian soils by instruments on Phoenix and MSL has demonstrated a release of CO2 at temperatures as low as 250-300 degC, much lower than the traditional decomposition temperatures of calcium or magnesium carbonates. Thermal decomposition temperature can depend on a number of factors such as instrument pressure and ramp rate, and sample particle size [6]. However, if the CO2 released at low temperatures is from carbonates, small particle size is the only effect that could have such a large impact on decomposition temperature, implying the presence of extremely fine-grained (i.e., "nanophase" or clay-sized) carbonates. We hypothesize that this lower temperature release is the signature of small particle-sized (clay-sized) carbonates formed by the weathering of primary minerals in dust or soils through interactions with atmospheric water and carbon dioxide and that this process may persist under current martian conditions. Preliminary work has shown that clay-sized carbonate grains can decompose at much lower temperatures than previously thought. The first work took carbonate, decomposed it to CaO, then flowed CO2 over these samples held at temperatures >100 degC to reform carbonates. Thermal analysis confirmed that carbonates were indeed formed and transmission electron microsopy was used to determine crystal sized were on the order of 10 nm. The next step used minerals such as diopside and wollastonite that were sealed in a glass tube with a CO2 and H2O source. After reacting these materials for a number of hours, thermal analysis demonstrated the formations of carbonates that decomposed at temperatures as low as 500 degC [7]. Further work is underway to carry out the weathering process under more Mars-like conditions (low pressure and low temperature) to determine if the carbonate decomposition temperature can be shifted to even lower temperatures, consistent with what has been detected by thermal analysis instruments on Mars.

  6. Hydrogen and Ferric Iron in Mars Materials

    NASA Technical Reports Server (NTRS)

    Dyar, Melinda D.

    2004-01-01

    Knowledge of oxygen and hydrogen fugacity is of paramount importance in constraining phase equilibria and crystallization processes of melts, as well as understanding the partitioning of elements between the cope and silicate portions of terrestrial planets. H and Fe(3+) must both be analyzed in order to reconstruct hydrogen and oxygen fugacities on Mars. To date, SIMS data have elucidated D/H and H contents of hydrous phases in SNC meteorites, but until now anhydrous martian minerals have not been systematically examined for trace hydrogen. Ferric iron has been quantified using XANES in many martian phases, but integrated studies of both Fe(3+) and H on the same spots are really needed to address the H budget. Finally, the effects of shock on both Fe(3+) and H in hydrous and anhydrous phases must be quantified. Thus, the overall goal of this research was to understand the oxygen and hydrogen fugacities under which martian samples crystallized. In this research one-year project, we approached this problem by 1) characterizing Fe(3+) and H contents of SNC meteorites using both bulk (Mossbauer spectroscopy and uranium extraction, respectively) and microscale (synchrotron micro-XANES and SIMS) methods; 2) relating Fe(3+) and H contents of martian minerals to their oxygen and hydrogen fugacities through analysis of experimentally equilibrated phases (for pyroxene) and through study of volcanic rocks in which the oxygen and hydrogen fugacities can be independently constrained (for feldspar); and 3) studying the effects of shock processes on Fe(3+) and H contents of the phases of interest. Results have been used to assess quantitatively the distribution of H and Fe(3+) among phases in the martian interior, which will better constrain the geodynamic processes of the interior, as well as the overall hydrogen and water budgets on Mars. There were no inventions funded by this research.

  7. Nanophase Magnetite and Pyrrhotite in ALH84001 Martian Meteorite: Evidence for an Abiotic Origin

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    The nanophase magnetite crystals in the black rims of pancake-shaped carbonate globules of the Martian meteorite ALH84001 have been studied extensively because of the claim by McKay et al.that they are biogenic in origin. A subpopulation of these magnetite crystals are reported to conform to a unique elongated shape called "truncated hexa-octahedral" or "THO" by Thomas-Keprta et al. They claim these THO magnetite crystals can only be produced by living bacteria thus forming a biomarker in the meteorite. In contrast, thermal decomposition of Fe-rich carbonate has been suggested as an alternate hypothesis for the elongated magnetite formation in ALH84001 carbonates. The experimental and observational evidence for the inorganic formation of nanophase magnetite and pyrrhotite in ALH84001 by decomposition of Fe-rich carbonate in the presence of pyrite are provided.

  8. Preparation of silica nanospheres and porous polymer membranes with controlled morphologies via nanophase separation

    PubMed Central

    2012-01-01

    We successfully synthesized two different structures, silica nanospheres and porous polymer membranes, via nanophase separation, based on a sol–gel process. Silica sol, which was in situ polymerized from tetraorthosilicate, was used as a precursor. Subsequently, it was mixed with a polymer that was used as a matrix component. It was observed that nanophase separation occurred after the mixing of polymer with silica sol and subsequent evaporation of solvents, resulting in organizing various structures, from random network silica structures to silica spheres. In particular, silica nanospheres were produced by manipulating the mixing ratio of polymer to silica sol. The size of silica beads was gradually changed from micro- to nanoscale, depending on the polymer content. At the same time, porous polymer membranes were generated by removing the silica component with hydrofluoric acid. Furthermore, porous carbon membranes were produced using carbon source polymer through the carbonization process. PMID:22873570

  9. Space Weathering on Asteroids: Formation of Nanophase Iron Particles and Spectral Change by Labolatory Simulations

    NASA Astrophysics Data System (ADS)

    Sasaki, S.; Nakamura, K.; Hamabe, Y.; Kurahashi, E.; Hiroi, T.

    2000-10-01

    Space weathering is the process where fast dust impacts as well as solar wind sputtering changes the optical properties of asteroid surfaces. It would explain the missing spectral link between ordinary chondrites and S-type asteroids. Formation of nanophase iron particles, which were found in the rim of lunar soils, may be responsible for the reflectance changes. Here we succeeded in forming nanophase iron particles in the vapor-deposited rim of pulse-laser treated olivine grain samples, showing significant spectral reddening. To simulate space weathering by impact heating of dust particles, we irradiated pellet samples of olivine and pyroxene grains (< 75 micron) with a pulse laser (1064 nm) with pulse duration 6-8 ns. [1]. Reflectance spectra were reduced and reddened: reflectance of olivine changed more significantly than that of pyroxene, which is compatible with compiled asteroid spectral data where olivine-rich asteroids have more reddened spectra than pyroxene-rich asteroids [2]. From irradiated pellet samples, altered (colored) surface grains were picked up and their thin sections (70-100nm thickness) were observed by TEM. In the grain rim region, nanophase particles were ubiquitous. EDS analysis showed the rim region is relatively rich in iron. Size of those particles, which were not observed in un-irradiated samples, is between several to 30nm. These nanophase particles are responsible for the change of optical properties such as darkening and reddening. Different from olivine grains, olivine crystal samples were hardly changed optically and no structural change was observed by TEM, although evaporation was confirmed during laser irradiation. Evaporated materials should escape quickly from flat crystal surfaces, whereas they may recondense and deposit on nearby grains or pellet samples. This suggests that the presence of regolith-like surface should be preferable for effective space weathering on asteroids. [1] Yamada, M. et al. (1999) Earth Planets Space 51, 1255-1265. [2] Hiroi, T. and Sasaki, S. (1999) LPSC XXX, 1444.

  10. Use of ferric sulfate: acid media for the desulfurization of model compounds of coal. [Dibenzothiophene, diphenyl sulfide, di-n-butyl sulfide

    SciTech Connect

    Clary, L.R.; Vermeulen, T.; Lynn, S.

    1980-12-01

    The objective of this work has been to investigate the ability of ferric sulfate-acid leach systems to oxidize the sulfur in model compounds of coal. Ferric iron-acid leach systems have been shown to be quite effective at removal of inorganic sulfur in coal. In this study, the oxidative effect of ferric iron in acid-leach systems was studied using dibenzothiophene, diphenyl sulfide, and di-n-butyl sulfide as models of organic sulfur groups in coal. Nitrogen and oxygen, as well as various transition metal catalysts and oxidants, were utilized in this investigation. Dibenzothiophene was found to be quite refractory to oxidation, except in the case where metavanadate was added, where it appears that 40% oxidation to sulfone could have occurred per hour at 150/sup 0/C and mild oxygen pressure. Diphenyl sulfide was selectively oxidized to sulfoxide and sulfone in an iron and oxygen system. Approximately 15% conversion to sulfone occurred per hour under these conditions. Some of the di-n-butyl sulfide was cracked to 1-butene and 1-butanethiol under similar conditions. Zinc chloride and ferric iron were used at 200/sup 0/C in an attempt to desulfonate dibenzothiophene sulfone, diphenyl sulfone, and di-n-butyl sulfone. Di-n-butyl sulfone was completely desulfurized on one hour and fragmented to oxidized parafins, while dibenzothiophene sulfone and diphenyl sulfone were unaffected. These results suggest that an iron-acid leach process could only selectively oxidize aryl sulfides under mild conditions, representing only 20% of the organic sulfur in coal (8% of the total sulfur). Removal through desulfonation once selective sulfur oxidation had occurred was only demonstrated for alkyl sulfones, with severe oxidation of the fragmented paraffins also occurring in one hour.

  11. Chalcopyrite concentrate leaching with biologically produced ferric sulphate.

    PubMed

    Kinnunen, P H-M; Heimala, S; Riekkola-Vanhanen, M-L; Puhakka, J A

    2006-09-01

    Biological ferric iron production was combined with ferric sulphate leaching of chalcopyrite concentrate and the effects of pH, Fe3+, temperature and solids concentration on the leaching were studied. The copper leaching rates were similar at pH of 1.0-1.8 and in the presence of 7-90 g L-1 Fe3+ despite massive iron precipitation with 90 g L-1 Fe3+. Increase of the leaching temperature from 50 degrees C to 86 degrees C and solids concentration from 1% to 10% increased the copper leaching rate. Increase in solids concentration from 1% to 10% decreased the copper yields from 80% to 40%. Stepwise addition of ferric iron did not improve the copper yields. CuFeS2, Ag and Cu1.96S potentials indicated the formation of a passivating layer, which consisted of jarosite and sulphur precipitates and which was responsible for the decreased leaching rates. PMID:16154742

  12. Impact of Iron-Reducing Bacteria on Metals and Radionuclides Adsorbed to Humic-Coated Iron(III) Oxides

    SciTech Connect

    Burgos, W. D.

    2005-02-01

    This is the final report for Grant No. DEFGO2-98ER62691 submitted to the DOE NABR Program. This research has focused on (1) the role of natural organic matter (NOM), quinines, and complexants in enhancing the biological reduction of solid-phase crystalline ferric oxides, (2) the effect of heavy metals (specifically zinc) and NOM on ferric oxide bioreduction, (3) the sorption of Me(II) [Cu(II), Fe(II), Mn(II) and Zn(II)] to ferric oxides and subsequent Me(II)-promoted phase transformations of the ferric oxides, and (4) the development of reaction-based biogeochemical models to numerically simulate our experimental results.

  13. 21 CFR 184.1307 - Ferric sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE ...sulfate, Fe2 (SO4 )3 CAS Reg. No. 10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II)...

  14. Mechanism of Bacterial Pyrite Oxidation

    PubMed Central

    Silverman, Melvin P.

    1967-01-01

    The oxidation by Ferrobacillus ferrooxidans of untreated pyrite (FeS2) as well as HCl-pretreated pyrite (from which most of the acid-soluble iron species were removed) was studied manometrically. Oxygen uptake was linear during bacterial oxidation of untreated pyrite, whereas with HCl-pretreated pyrite both a decrease in oxygen uptake at 2 hr and nonlinear oxygen consumption were observed. Ferric sulfate added to HCl-pretreated pyrite restored approximately two-thirds of the decrease in total bacterial oxygen uptake and caused oxygen uptake to revert to nearly linear kinetics. Ferric sulfate also oxidized pyrite in the absence of bacteria and O2; recovery of ferric and ferrous ions was in excellent agreement with the reaction Fe2(SO4)3 + FeS2 = 3FeSO4 + 2S, but the elemental sulfur produced was negligible. Neither H2S nor S2O32? was a product of the reaction. It is probable that two mechanisms of bacterial pyrite oxidation operate concurrently: the direct contact mechanism which requires physical contact between bacteria and pyrite particles for biological pyrite oxidation, and the indirect contact mechanism according to which the bacteria oxidize ferrous ions to the ferric state, thereby regenerating the ferric ions required for chemical oxidation of pyrite. PMID:6051342

  15. The distribution of ferric iron within the Earth's interior and evolution in the mantle's redox state. (Invited)

    NASA Astrophysics Data System (ADS)

    Frost, D. J.; Myhill, R.; Ziberna, L.

    2013-12-01

    The Earth's redox state has influenced the nature of volatile species within both the Earth and mantle derived magmas. During core formation equilibrium with metallic iron would have imposed a low oxygen fugacity, but some of the oldest magmas on Earth indicate a mantle oxygen fugacity more oxidised than this. One mechanism for early mantle oxidation is through disproportionation of ferrous iron in the lower mantle to form ferric iron in magnesium silicate perovskite and iron metal. This is supported by evidence showing that Al-bearing perovskite synthesised in equilibrium with iron metal contains at least 50 % of iron in the ferric state. Loss of some of the resulting iron metal to the core may have rendered the lower mantle more oxidised, which may then have mixed with the upper mantle. The questions remain, however, to what extent might the lower mantle have been oxidised by loss of metal and whether mixing with the upper mantle was complete? To address these issues requires interpretation of evidence for the oxidation state of both normal sublithospheric mantle and plume source mantle, which may bring material from the lower mantle. We have performed experiments to understand redox processes that may potentially mask higher ferric iron contents in the deeper upper and lower mantle. Carbon, for example, should exist in reduced form as diamond or dissolved in metallic alloy in the deep mantle but will oxidise during decompression of the sublithospheric mantle causing reduction of ferric iron closer to the surface. We consider this and other effects that may imply the existence of a more oxidised deeper mantle source than previously considered.

  16. Ferric iron in mantle-derived garnets

    Microsoft Academic Search

    Robert W. Luth; David Virgo; Francis R. Boyd; Bernard J. Wood

    1990-01-01

    The oxidation state of a mantle assemblage may be defined by heterogeneous reactions between oxygen and iron-bearing minerals. In spinel lherzolites, the presence of Fe3+ in spinel allows use of the assemblage olivine-orthopyroxene-spinel to define fO2 at fixed T and P. As a first step towards establishing an analogous reaction for garnet lherzolites, garnets from mantle-derived xenoliths from South Africa

  17. Ferric chloride-graphite intercalation compounds prepared from graphite fluoride

    Microsoft Academic Search

    Ching-Cheh Hung

    1995-01-01

    The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400 °C. The graphite fluorides used for this reaction have an sp3 electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in

  18. Spectrophotometric Ferric Ion Biosensor From Pseudomonas fluorescens Culture

    E-print Network

    Mittal, Aditya

    ARTICLE Spectrophotometric Ferric Ion Biosensor From Pseudomonas fluorescens Culture Varun Gupta InterScience (www.interscience.wiley.com). DOI 10.1002/bit.21754 ABSTRACT: Pseudomonas fluorescens role in sensing and uptake of iron (Rachid and Ahmed, 2005). Pseudomonas fluorescens is one

  19. Use of Ferric Sulfate to Control Hepatic Bleeding

    PubMed Central

    Nouri, Saeed; Sharif, Mohammad Reza

    2015-01-01

    Background: Controlling parenchymal hemorrhage, especially in liver parenchyma, despite all the progress in surgical science, is still one of the challenges surgeons face. Therefore, search for an effective method to control hepatic bleeding is an important research priority. Objectives: This study attempted to determine the haemostatic effect of ferric sulfate and compare it with the standard method (suturing technique). Materials and Methods: In this animal model study, 60 male Wistar rats were used. An incision (2 cm in length and 1/2 cm in depth) was made on each rat’s liver and the hemostasis time was measured using ferric sulfate with different concentrations (5%, 10%, 15%, 25%, and 50%) and then using simple suturing. The liver tissue was assessed for pathological changes. Results: In all the groups, complete hemostasis occurred. Hemostasis times of different concentrations of ferric sulfate were significantly less than those of the control group (P < 0.001). Conclusions: Ferric sulfate was effective in controlling hepatic bleeding in rats.

  20. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...ammonium citrate) is prepared by the reaction of ferric hydroxide with citric acid...Reg. No. 1332-98-5) is a complex salt of undetermined structure composed of...Reg. No. 1333-00-2) is a complex salt of undetermined structure composed...

  1. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...ammonium citrate) is prepared by the reaction of ferric hydroxide with citric acid...Reg. No. 1332-98-5) is a complex salt of undetermined structure composed of...Reg. No. 1333-00-2) is a complex salt of undetermined structure composed...

  2. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...ammonium citrate) is prepared by the reaction of ferric hydroxide with citric acid...Reg. No. 1332-98-5) is a complex salt of undetermined structure composed of...Reg. No. 1333-00-2) is a complex salt of undetermined structure composed...

  3. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...ammonium citrate) is prepared by the reaction of ferric hydroxide with citric acid...Reg. No. 1332-98-5) is a complex salt of undetermined structure composed of...Reg. No. 1333-00-2) is a complex salt of undetermined structure composed...

  4. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...ammonium citrate) is prepared by the reaction of ferric hydroxide with citric acid...Reg. No. 1332-98-5) is a complex salt of undetermined structure composed of...Reg. No. 1333-00-2) is a complex salt of undetermined structure composed...

  5. 40 CFR 180.1191 - Ferric phosphate; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Ferric phosphate; exemption from the requirement of a...From Tolerances § 180.1191 Ferric phosphate; exemption from the requirement of a...of the biochemical pesticide, ferric phosphate (FePO4 , CAS No....

  6. 40 CFR 180.1191 - Ferric phosphate; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Ferric phosphate; exemption from the requirement of a...From Tolerances § 180.1191 Ferric phosphate; exemption from the requirement of a...of the biochemical pesticide, ferric phosphate (FePO4 , CAS No....

  7. 40 CFR 180.1191 - Ferric phosphate; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Ferric phosphate; exemption from the requirement of a...From Tolerances § 180.1191 Ferric phosphate; exemption from the requirement of a...of the biochemical pesticide, ferric phosphate (FePO4 , CAS No....

  8. 40 CFR 180.1191 - Ferric phosphate; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Ferric phosphate; exemption from the requirement of a...From Tolerances § 180.1191 Ferric phosphate; exemption from the requirement of a...of the biochemical pesticide, ferric phosphate (FePO4 , CAS No....

  9. 40 CFR 180.1191 - Ferric phosphate; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Ferric phosphate; exemption from the requirement of a...From Tolerances § 180.1191 Ferric phosphate; exemption from the requirement of a...of the biochemical pesticide, ferric phosphate (FePO4 , CAS No....

  10. Pre-terrestrial oxidation products in carbonaceous meteorites identified by Mossbauer spectroscopy

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.; Fisher, Duncan S.

    1991-01-01

    The occurrence of ferric bearing assemblages, comprising phyllosilicates, oxide hydroxides and magnetite, in carbonaceous chondrites (CC) indicates that these meteorites underwent pre-terrestrial, sub-aqueous oxidation reactions. Reported here are results of a Mossbauer spectral study of a suite of CC demonstrating that a variety of ferrous and ferric bearing phases may be distinguished in different classes of this meteorite type.

  11. Ferric saponite and serpentine in the nakhlite martian meteorites

    NASA Astrophysics Data System (ADS)

    Hicks, L. J.; Bridges, J. C.; Gurman, S. J.

    2014-07-01

    Transmission electron microscopy and Fe-K X-ray absorption spectroscopy have been used to determine structure and ferric content of the secondary phase mineral assemblages in the nakhlite martian meteorites, NWA 998, Lafayette, Nakhla, GV, Y 000593, Y 000749, MIL 03346, NWA 817, and NWA 5790. The secondary phases are a rapidly cooled, metastable assemblage that has preserved Mg# and Ca fractionation related to distance from the fluid source, for most of the nakhlites, though one, NWA 5790, appears not to have experienced a fluid pathway. All nine nakhlite samples have also been analysed with scanning electron microscopy, electron probe micro analysis, Bright Field high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction. By measuring the energy position of the Fe-K XANES 1s ? 3d pre-edge transition centroid we calculate the ferric content of the minerals within the nakhlite meteorites. The crystalline phyllosilicates and amorphous silicate of the hydrothermal deposits filling the olivine fractures are found to have variable Fe3+/?Fe values ranging from 0.4 to 0.9. In Lafayette, the central silicate gel parts of the veins are more ferric than the phyllosilicates around it, showing that the fluid became increasingly oxidised. The mesostasis of Lafayette and NWA 817 also have phyllosilicate, which have a higher ferric content than the olivine fracture deposits, with Fe3+/?Fe values of up to 1.0. Further study, via TEM analyses, reveal the Lafayette and NWA 817 olivine phyllosilicates to have 2:1 T-O-T lattice structure with a the d001-spacing of 0.96 nm, whereas the Lafayette mesostasis phyllosilicates have 1:1 T-O structure with d001-spacings of 0.7 nm. Based on our analyses, the phyllosilicate found within the Lafayette olivine fractures is trioctahedral ferric saponite (Ca0.2K0.1)?0.3(Mg2.6Fe2+1.3Fe3+1.7Mn0.1)?5.7[(Si6.7AlIV0.9Fe3+0.4)?8.0O20](OH)4·nH2O, and that found in the mesostasis fractures is an Fe-serpentine (Ca0.1Mg0.7Fe3+1.0AlVI0.4)?2.2[Si2O5]OH4, with a ferric gel of similar composition in Lafayette and found as fracture fills throughout the other nakhlites.

  12. The leaching of chalcopyrite with ferric chloride

    NASA Astrophysics Data System (ADS)

    Hirato, Tetsuji; Kinoshita, Makoto; Awakura, Yasuhiro; Majima, Hiroshi

    1986-01-01

    A comparative study of electrochemical leaching and chemical leaching of chalcopyrite was done to elucidate the leaching mechanism of chalcopyrite with FeCl3. The leaching rate of chalcopyrite exhibits a half order dependency on the FeCl3 concentration, whereas it is independent of the FeCl2 concentration. The mixed potential of chalcopyrite exhibits a 72 mV · decade-1 dependency upon FeCl3 concentration; no influence on the mixed potential was observed by the addition of FeCl2. In FeCl3 solutions acidified with HC1, the predominant chemical species of Fe(III) was found to be FeCl{2/u+} from equilibrium calculations. The concentration of this species is approximately proportional to the amount of FeCl3 added to the solutions. Based on these observations, an electrochemical mechanism is proposed which involves the oxidation of chalcopyrite and the reduction of FeCl{2/+}, the predominant species of Fe(III). By converting the leaching rate to electric current density, i, 140 mV · decade-1 dependency of mixed potential, E, against log i is obtained. This dependency of the chemical leaching of chalcopyrite with FeCl3 as well as its activation energy agree with those for electrochemical leaching. These findings strongly support the electrochemical mechanism of FeCl3 leaching of chalcopyrite.

  13. Ferric chloride-induced murine carotid arterial injury: A model of redox pathology?

    PubMed Central

    Li, Wei; McIntyre, Thomas M.; Silverstein, Roy L.

    2013-01-01

    Ferric chloride (FeCl3) induced vascular injury is a widely used model of occlusive thrombosis that reports platelet activation in the context of an aseptic closed vascular system. This model is based on redox-induced endothelial cell injury, which is simple and sensitive to both anticoagulant and anti-platelets drugs. The time required for platelet aggregation to occlude blood flow gives a quantitative measure of vascular damage that is pathologically relevant to thrombotic disease. We have refined the traditional FeCl3-induced carotid artery model making the data highly reproducible with lower variation. This paper will describe our artifices and report the role of varying the oxidative damage by varying FeCl3 concentrations and exposure. To explore a maximum difference between experimental groups, adjustment of the selected FeCl3 dose and exposure duration may be necessary. PMID:25101237

  14. Ferric ion leaching of chalcopyrites from different localities

    NASA Astrophysics Data System (ADS)

    Dutrizac, J. E.

    1991-12-01

    Carefully sized and characterized chalcopyrite concentrates were produced from eleven different geographical localities, and were subsequently leached in both ferric chloride-hydrochloric acid and ferric sulfate-sulfuric acid media. When the leaching rates were corrected for the amount of CuFeS2 in the particular sample, similar leaching rates (±50 pet) were observed for all eleven chalcopyrites under all experimental conditions. Furthermore, all the relatively pure chalcopyrites leached according to the same reaction and yielded >95 pet elemental sulfur as a sulfidic reaction product. In light of the current experimental observations, various reasons are offered for the order of magnitude variations in the chalcopyrite leaching rates often reported in the literature.

  15. Ferric ion leaching of chalcopyrites from different localities

    NASA Astrophysics Data System (ADS)

    Dutrizac, J. E.

    1982-09-01

    Carefully sized and characterized chalcopyrite concentrates were produced from eleven different geographical localities, and were subsequently leached in both ferric chloride-hydrochloric acid and ferric sulfate-sulfuric acid media. When the leaching rates were corrected for the amount of CuFeS2 in the particular sample, similar leaching rates (±50 pct) were observed for all eleven chalcopyrites under all experimental conditions. Furthermore, all the relatively pure chalcopyrites leached according to the same reaction and yielded >95 pct elemental sulfur as a sulfidic reaction product. In light of the current experimental observations, various reasons are offered for the order of magnitude variations in the chalcopyrite leaching rates often reported in the literature.

  16. Pharmacokinetics of iron salts and ferric hydroxide-carbohydrate complexes.

    PubMed

    Geisser, P; Müller, A

    1987-01-01

    Pharmacokinetic measurements of ferrous sulphate and ferric hydroxide-polymaltose complex on anaemic and non-anaemic rats have shown different postabsorption serum iron levels, invasion and elimination constants and distribution volumes for the two preparations. But nevertheless the absorption and utilization ratios of iron from both preparations are equal. It is therefore not justified to calculate utilization ratios for chemically different iron preparations on the basis of postabsorption serum iron measurements. Similar pharmacokinetic differences of these two iron preparations could also be found in clinical trials, which means that different serum iron increase results in an equal utilization ratio for both preparations. It is clear that ferrous sulphate and ferric hydroxide-polymaltose complex must have a different absorption mechanism. The postulated absorption mechanism is in agreement with all the facts known today and does explain the pharmacokinetic difference between the investigated preparations. PMID:3566862

  17. Flavin-mediated reduction of ferric leghemoglobin from soybean nodules

    Microsoft Academic Search

    Manuel Becana; Marvin L. Salin; Lin Ji; Robert V. Klucas

    1991-01-01

    The reduction of ferric leghemoglobin (Lb3+) from soybean (Glycine max (L.) Merr.) nodules by riboflavin, FMN and FAD in the presence of NAD(P)H was studied in vitro. The system NAD(P)H + flavin reduced Lb3+ to oxyferrous (Lb2+ · O2) or deoxyferrous (Lb2+) leghemoglobin in aerobic or anaerobic conditions, respectively. In the absence of O2 the reaction was faster and more

  18. Quantitative determination of cesium binding to ferric hexacyanoferrate: Prussian blue

    Microsoft Academic Search

    Patrick J. Faustino; Yongsheng Yang; Joseph J. Progar; Charles R. Brownell; Nakissa Sadrieh; Joan C. May; Eldon Leutzinger; Eric P. Duffy; Florence Houn; Sally A. Loewke; Vincent J. Mecozzi; Christopher D. Ellison; Mansoor A. Khan; Ajaz S. Hussain; Robbe C. Lyon

    2008-01-01

    Ferric hexacyanoferrate (Fe4III[FeII(CN)6]3), also known as insoluble Prussian blue (PB) is the active pharmaceutical ingredient (API) of the drug product, Radiogardase®. Radiogardase® is the first FDA approved medical countermeasure for the treatment of internal contamination with radioactive cesium (Cs) or thallium in the event of a major radiological incident such as a “dirty bomb”. A number of pre-clinical and clinical

  19. Mineralogical changes occurring during the ferric lon leaching of bornite

    NASA Astrophysics Data System (ADS)

    Dutrizac, J. E.; Chen, T. T.; Jambor, J. L.

    1985-12-01

    The reaction products formed during the leaching of bornite in either ferric chloride or ferric sulfate media depend on the leaching conditions as well as the particle size of the bornite. The extent of dissolution is always more vigorous in the ferric chloride system and increases with increasing temperature in either system. The reaction initially involves the rapid outward diffusion of copper to form slightly nonstoichiometric bornite (Cu5-xFeS4), chalcopyrite, and covellite. The non-stoichiometric bornite is progressively converted to a Cu3FeS4 phase, which varies considerably in its composition, and to covellite. Although the reaction at low temperature terminates at the Cu3FeS4 phase, leaching at higher temperatures results in further dissolution to elemental sulfur and soluble Cu2+ and Fe2+. The leaching of massive bornite illustrates the complexities of the leaching reaction more clearly than is observed for the finely paniculate bornite. In leached massive bornite, a distinct covellite zone appears in the Cu3FeS4 phase; as well, chalcopyrite exsolution lamellae rimmed by a copper sulfide (possibly digenite) appear in the covellite zone, in the Cu3FeS4 phase, and in the nonstoichiometric bornite. The experimental leaching results, especially those involving massive bornite, are generally consistent with the mineralogical trends produced by supergene alteration of bornite ores, but a significant difference is that the Cu3FeS4 phase does not correspond closely to the mineral idaite.

  20. Anhydrous ferric chloride as an alkylation catalyst: The condensation of 2-methylpropene and benzene, preparation and identification of several fractions.

    E-print Network

    Mommessin, Pierre Robert

    1950-01-01

    . - BSTC. r, Ber, , 2 /, 1Wi-~l and make their identification. However, it was possible to oxidize the fraction and to obtain terephthalic acid in a very low yield. This indicate the presence of 1&4-di-alkyl-benzene homologs in this fraction, O ? O O... . mer. CONCLUSIONS 1. When benzene is alkylated with 2-methylpropene in the presence of ferric chloride the following hydrocarbons can be identified among the products of the reaction: t-butylbenzene, t-amylbenzene, t-hexylbenzene, l-isopropy1-3-t...

  1. Formation of Metallic Nanophases in Polymeric Matrices for Space Applications

    NASA Technical Reports Server (NTRS)

    Orwoll, Robert A.; Thompson, David W.

    1999-01-01

    There are a select number of polyimides which are soluble in organic media. Incorporation of hexafluoroisopropylidene groups is a route to achieving solubility. Such fluorinated polyimides have desirable properties for processing and electronic purposes; however, they often have linear coefficients of thermal expansion (CTE) which are well above those for metals and inorganic oxides or ceramics with which they might be bonded. We have developed a synthesis of composite inorganic-polyimide films using diaquotris(2,4-pentane-dionato)lanthanam(III) as the inorganic precursor and two soluble polyimides formed from 2,2-bis(3,4- dicarboxyphenyl)hexafluoro-propane (6FDA) and 1,3-bis(3-aminophenoxy)benzene (APB) or 2,2-bis[4-(4-aminophenoxy)phenyllhexafluoropropane (4-BDAF). A primary goal of our work was to control the linear CTE in these fluorinated polymer composites without adversely affecting mechanical or other thermal properties.

  2. Ferric citrate controls phosphorus and delivers iron in patients on dialysis.

    PubMed

    Lewis, Julia B; Sika, Mohammed; Koury, Mark J; Chuang, Peale; Schulman, Gerald; Smith, Mark T; Whittier, Frederick C; Linfert, Douglas R; Galphin, Claude M; Athreya, Balaji P; Nossuli, A Kaldun Kaldun; Chang, Ingrid J; Blumenthal, Samuel S; Manley, John; Zeig, Steven; Kant, Kotagal S; Olivero, Juan Jose; Greene, Tom; Dwyer, Jamie P

    2015-02-01

    Patients on dialysis require phosphorus binders to prevent hyperphosphatemia and are iron deficient. We studied ferric citrate as a phosphorus binder and iron source. In this sequential, randomized trial, 441 subjects on dialysis were randomized to ferric citrate or active control in a 52-week active control period followed by a 4-week placebo control period, in which subjects on ferric citrate who completed the active control period were rerandomized to ferric citrate or placebo. The primary analysis compared the mean change in phosphorus between ferric citrate and placebo during the placebo control period. A sequential gatekeeping strategy controlled study-wise type 1 error for serum ferritin, transferrin saturation, and intravenous iron and erythropoietin-stimulating agent usage as prespecified secondary outcomes in the active control period. Ferric citrate controlled phosphorus compared with placebo, with a mean treatment difference of -2.2±0.2 mg/dl (mean±SEM) (P<0.001). Active control period phosphorus was similar between ferric citrate and active control, with comparable safety profiles. Subjects on ferric citrate achieved higher mean iron parameters (ferritin=899±488 ng/ml [mean±SD]; transferrin saturation=39%±17%) versus subjects on active control (ferritin=628±367 ng/ml [mean±SD]; transferrin saturation=30%±12%; P<0.001 for both). Subjects on ferric citrate received less intravenous elemental iron (median=12.95 mg/wk ferric citrate; 26.88 mg/wk active control; P<0.001) and less erythropoietin-stimulating agent (median epoetin-equivalent units per week: 5306 units/wk ferric citrate; 6951 units/wk active control; P=0.04). Hemoglobin levels were statistically higher on ferric citrate. Thus, ferric citrate is an efficacious and safe phosphate binder that increases iron stores and reduces intravenous iron and erythropoietin-stimulating agent use while maintaining hemoglobin. PMID:25060056

  3. Performance comparison of Fenton process, ferric coagulation and H 2O 2\\/pyridine\\/Cu(II) system for decolorization of Remazol Turquoise Blue G-133

    Microsoft Academic Search

    Ulusoy Bali; Bünyamin Karagözo?lu

    2007-01-01

    This paper evaluates the Fenton process (involving oxidation and coagulation), ferric coagulation and H2O2\\/pyridine\\/Cu(II) system for the removal of color from a synthetic textile wastewater containing polyvinyl alcohol and a reactive dyestuff, Remazol Turquoise Blue G-133. Experiments were conducted to investigate the effects of operating variables such as pH, coagulant dose, polyelectrolyte type, H2O2 and Fe(II) concentrations, optimum pyridine and

  4. Deposition rates of oxidized iron on Mars

    NASA Technical Reports Server (NTRS)

    Burns, R. G.

    1993-01-01

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

  5. Ferric Carboxymaltose-Mediated Attenuation of Doxorubicin-Induced Cardiotoxicity in an Iron Deficiency Rat Model

    PubMed Central

    Toblli, Jorge Eduardo; Rivas, Carlos; Cao, Gabriel; Giani, Jorge Fernando; Dominici, Fernando Pablo

    2014-01-01

    Since anthracycline-induced cardiotoxicity (AIC), a complication of anthracycline-based chemotherapies, is thought to involve iron, concerns exist about using iron for anaemia treatment in anthracycline-receiving cancer patients. This study evaluated how intravenous ferric carboxymaltose (FCM) modulates the influence of iron deficiency anaemia (IDA) and doxorubicin (3–5?mg per kg body weight [BW]) on oxidative/nitrosative stress, inflammation, and cardiorenal function in spontaneously hypertensive stroke-prone (SHR-SP) rats. FCM was given as repeated small or single total dose (15?mg iron per kg BW), either concurrent with or three days after doxorubicin. IDA (after dietary iron restriction) induced cardiac and renal oxidative stress (markers included malondialdehyde, catalase, Cu,Zn-superoxide dismutase, and glutathione peroxidase), nitrosative stress (inducible nitric oxide synthase and nitrotyrosine), inflammation (tumour necrosis factor-alpha and interleukin-6), and functional/morphological abnormalities (left ventricle end-diastolic and end-systolic diameter, fractional shortening, density of cardiomyocytes and capillaries, caveolin-1 expression, creatinine clearance, and urine neutrophil gelatinase-associated lipocalin) that were aggravated by doxorubicin. Notably, iron treatment with FCM did not exacerbate but attenuated the cardiorenal effects of IDA and doxorubicin independent of the iron dosing regimen. The results of this model suggest that intravenous FCM can be used concomitantly with an anthracycline-based chemotherapy without increasing signs of AIC. PMID:24876963

  6. Ferric carboxymaltose-mediated attenuation of Doxorubicin-induced cardiotoxicity in an iron deficiency rat model.

    PubMed

    Toblli, Jorge Eduardo; Rivas, Carlos; Cao, Gabriel; Giani, Jorge Fernando; Funk, Felix; Mizzen, Lee; Dominici, Fernando Pablo

    2014-01-01

    Since anthracycline-induced cardiotoxicity (AIC), a complication of anthracycline-based chemotherapies, is thought to involve iron, concerns exist about using iron for anaemia treatment in anthracycline-receiving cancer patients. This study evaluated how intravenous ferric carboxymaltose (FCM) modulates the influence of iron deficiency anaemia (IDA) and doxorubicin (3-5?mg per kg body weight [BW]) on oxidative/nitrosative stress, inflammation, and cardiorenal function in spontaneously hypertensive stroke-prone (SHR-SP) rats. FCM was given as repeated small or single total dose (15?mg iron per kg BW), either concurrent with or three days after doxorubicin. IDA (after dietary iron restriction) induced cardiac and renal oxidative stress (markers included malondialdehyde, catalase, Cu,Zn-superoxide dismutase, and glutathione peroxidase), nitrosative stress (inducible nitric oxide synthase and nitrotyrosine), inflammation (tumour necrosis factor-alpha and interleukin-6), and functional/morphological abnormalities (left ventricle end-diastolic and end-systolic diameter, fractional shortening, density of cardiomyocytes and capillaries, caveolin-1 expression, creatinine clearance, and urine neutrophil gelatinase-associated lipocalin) that were aggravated by doxorubicin. Notably, iron treatment with FCM did not exacerbate but attenuated the cardiorenal effects of IDA and doxorubicin independent of the iron dosing regimen. The results of this model suggest that intravenous FCM can be used concomitantly with an anthracycline-based chemotherapy without increasing signs of AIC. PMID:24876963

  7. Properties of the Complex Between Recombinant Human Progastrin and Ferric Ions

    Microsoft Academic Search

    Graham S. Baldwin

    2004-01-01

    Binding of ferric ions to the hormone glycine-extended gastrin17 is essential for biological activity (Pannequin, J., et al. (2002). J. Biol. Chem.277: 48602–48609). The aims of the current study were to determine the properties of the complex between recombinant human progastrin6–80 and ferric ions. The stoichiometry and affinity of ferric ion binding were determined by fluorescence spectroscopy. The selectivity of

  8. Reaction mechanism for the ferric chloride leaching of sphalerite

    NASA Astrophysics Data System (ADS)

    Warren, G. W.; Henein, H.; Jin, Zuo-Mei

    1985-12-01

    Reaction mechanisms for the ferric chloride leaching of sphalerite are proposed based on data obtained in leaching and dual cell experiments presented in this work and in a previous study. The results from the leaching experiments show that at low concentrations the rate is proportional to [Fe3+]T 0.5 and [Cl-]T 0.43 but at higher concentrations the reaction order with respect to both [Fe3+]T and [Cl-]T decreases. Using dual cell experiments which allow the half cell reactions to be separated, increased rates are observed when NaCl is added to the anolyte and to the catholyte. The increase in rate is attributed to a direct, anodic electrochemical reaction of Cl- with the mineral. When NaCl is added only to the catholyte, a decrease in the rate is observed due to a decrease in the E 0 of the cathode which is attributed to the formation of ferric-chloro complexes. Several possible electrochemical mechanisms and mathematical models based on the Butler-Volmer relation are delineated, and of these, one model is selected which accounts for the experimentally observed changes in reaction order for both Fe3+ and Cl-. This analysis incorporates a charge transfer process for each ion and an adsorption step for ferric and chloride ions. The inhibiting effect of Fe2+ noted by previous investigators is also accounted for through a similar model which includes back reaction kinetics for Fe2+. The proposed models successfully provide a theoretical basis for describing the role of Cl-, Fe3+, and Fe2+ as well as their interrelationship in zinc sulfide leaching reactions. Possible applications of these results to chloride leaching systems involving other sulfides or complex sulfides are considered.

  9. Ferric and cobaltous hydroacid complexes for forward osmosis (FO) processes.

    PubMed

    Ge, Qingchun; Fu, Fengjiang; Chung, Tai-Shung

    2014-07-01

    Cupric and ferric hydroacid complexes have proven their advantages as draw solutes in forward osmosis in terms of high water fluxes, negligible reverse solute fluxes and easy recovery (Ge and Chung, 2013. Hydroacid complexes: A new class of draw solutes to promote forward osmosis (FO) processes. Chemical Communications 49, 8471-8473.). In this study, cobaltous hydroacid complexes were explored as draw solutes and compared with the ferric hydroacid complex to study the factors influencing their FO performance. The solutions of the cobaltous complexes produce high osmotic pressures due to the presence of abundant hydrophilic groups. These solutes are able to dissociate and form a multi-charged anion and Na(+) cations in water. In addition, these complexes have expanded structures which lead to negligible reverse solute fluxes and provide relatively easy approaches in regeneration. These characteristics make the newly synthesized cobaltous complexes appropriate as draw solutes. The FO performance of the cobaltous and ferric-citric acid (Fe-CA) complexes were evaluated respectively through cellulose acetate membranes, thin-film composite membranes fabricated on polyethersulfone supports (referred as TFC-PES), and polybenzimidazole and PES dual-layer (referred as PBI/PES) hollow fiber membranes. Under the conditions of DI water as the feed and facing the support layer of TFC-PES FO membranes (PRO mode), draw solutions at 2.0 M produced relatively high water fluxes of 39-48 LMH (L m(-2) hr(-1)) with negligible reverse solute fluxes. A water flux of 17.4 LMH was achieved when model seawater of 3.5 wt.% NaCl replaced DI water as the feed and 2.0 M Fe-CA as the draw solution under the same conditions. The performance of these hydroacid complexes surpasses those of the synthetic draw solutes developed in recent years. This observation, along with the relatively easy regeneration, makes these complexes very promising as a novel class of draw solutes. PMID:24768702

  10. Prevention of Acid Mine Drainage Through Complexation of Ferric Iron by Soluble Microbial Growth Products

    NASA Astrophysics Data System (ADS)

    Pandey, S.; Yacob, T. W.; Silverstein, J.; Rajaram, H.; Minchow, K.; Basta, J.

    2011-12-01

    Acid mine drainage (AMD) is a widespread environmental problem with deleterious impacts on water quality in streams and watersheds. AMD is generated largely by the oxidation of metal sulfides (i.e. pyrite) by ferric iron. This abiotic reaction is catalyzed by conversion of ferrous to ferric iron by iron and sulfur oxidizing microorganisms. Biostimulation is currently being investigated as an attempt to inhibit the oxidation of pyrite and growth of iron oxidizing bacteria through addition of organic carbon. This may stimulate growth of indigenous communities of acidophilic heterotrophic bacteria to compete for oxygen. The goal of this research is to investigate a secondary mechanism associated with carbon addition: complexation of free Fe(III) by soluble microbial growth products (SMPs) produced by microorganisms growing in waste rock. Exploratory research at the laboratory scale examined the effect of soluble microbial products (SMPs) on the kinetics of oxidation of pure pyrite during shaker flask experiments. The results confirmed a decrease in the rate of pyrite oxidation that was dependent upon the concentration of SMPs in solution. We are using these data to verify results from a pyrite oxidation model that accounts for SMPs. This reactor model involves differential-algebraic equations incorporating total component mass balances and mass action laws for equilibrium reactions. Species concentrations determined in each time step are applied to abiotic pyrite oxidation rate expressions from the literature to determine the evolution of total component concentrations. The model was embedded in a parameter estimation algorithm to determine the reactive surface area of pyrite in an abiotic control experiment, yielding an optimized value of 0.0037 m2. The optimized model exhibited similar behavior to the experiment for this case; the root mean squared of residuals for Fe(III) was calculated to be 7.58 x 10-4 M, which is several orders of magnitude less than the actual Fe(III) concentrations. The model was refined to include Fe(III)-SMP complexes, but these are not well documented and vary depending upon the nature and origin of the growth products. Well known chelating agents form predictable complexes with Fe(III) iron through documented complexation reactions. If chelation of soluble Fe(III) by SMPs is similar to such a chelator, the latter may be used as a basis to parameterize inhibition of pyrite oxidation due to complexation of Fe(III) by SMPs. Fe(III) complexation by known ligands or SMPs may adequately be represented by a bulk complex whose stability constant reflects the extent to which free Fe(III) is diminished. The stability constant may differ among the different SMPs experiments depending upon their origin but can be optimized for each case using inverse modeling techniques. We present results from these inverse modeling exercises to demonstrate the validity of using bulk Fe(III)-SMP complexes to explain inhibition of pyrite oxidation in the presence of SMPs. Our results will facilitate the design of in-situ carbon addition strategies by determining organic carbon dose intensity and application frequency required to effectively mitigate impacts on receiving water quality.

  11. The Optical Properties of Nanophase Iron: Investigation of a Space Weathering Analog

    NASA Technical Reports Server (NTRS)

    Noble, S. K.; Pieters, C. M.; Keller, L. P.

    2003-01-01

    It is known that space weathering, in particular the nanophase iron (npFe(sup 0)) created via vapor and/or sputter deposition, has distinct and predictable effects on the optical properties of lunar soils. In addition to the attenuation of absorption bands, weathering introduces a characteristic continuum which is controlled by the amount of npFe(sup 0) present. The shape of this continuum may also be controlled by the size of the npFe(sup 0) grains. It is thought that small npFe(sup 0) grains result in reddening, while larger grains only darken the material. To investigate this phenomenon we have created a lunar weathering analog by impregnating silica gel powders with npFe(sup 0) following the methods presented.

  12. Direct Measurement of the Crystallographically Sensitive Atomic Termination of Nanophase Cerium Dioxide

    NASA Astrophysics Data System (ADS)

    Young, N. P.; Haigh, S. J.; Sawada, H.; Takayanagi, K.; Kirkland, A. I.

    2012-07-01

    Aberration-corrected high-resolution transmission electron microscopy (HRTEM) was used to study the surface termination of nanophase cerium dioxide particles. Application of computational exit-wave restoration and comparison with simulations confirmed the {111} surfaces to have an oxygen termination, and while structurally unstable at room temperature the {100} facets exhibited a metal terminating plane. This crystallographically sensitive atomic termination was found to be maintained under the reducing conditions of the electron beam. During electron beam irradiation, Electron Energy Loss Spectroscopy (EELS) analysis revealed that a change from Ce4+ to Ce3+ originates at the particle surface, and gradually extends into the particle as reduction continues. The results aid understanding of the oxygen buffering mechanism in cerium dioxide, and provide valuable insight into the use of CeO2 nanoparticles in catalysis.

  13. Ultraviolet and white photon avalanche upconversion in Ho{sup 3+}-doped nanophase glass ceramics

    SciTech Connect

    Lahoz, F.; Martin, I.R.; Calvilla-Quintero, J.M. [Departmento de Fisica Fundamental y Experimental, Electronica y Sistemas, University of La Laguna, 38206 La Laguna, Tenerife (Spain)

    2005-01-31

    Ho{sup 3+}-doped fluoride nanophase glass ceramics have been synthesized from silica-based oxyfluoride glass. An intense white emission light is observed by the naked eye under near infrared excitation at 750 nm. This visible upconversion is due to three strong emission bands in the primary color components, red, green, and blue. Besides, ultraviolet signals are also recorded upon the same excitation wavelength. The excitation mechanism of both the ultraviolet and the visible emissions is a photon avalanche process with a relatively low pump power threshold at about 20 mW. The total upconverted emission intensity has been estimated to increase by about a factor of 20 in the glass ceramic compared to the precursor glass, in which an avalanche type mechanism is not generated.

  14. Iron Amendment and Fenton Oxidation of MTBE-Spent Granular Activated Carbon

    EPA Science Inventory

    Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves Fe amendment to the GAC to catalyze H2O2 reactions and to enhance the rate of MTBE oxidation and GAC regeneration. Four forms of iron (ferric sulfate, ferric chloride, fer...

  15. Particulate and THM precursor removal with ferric chloride

    SciTech Connect

    Childress, A.E.; Vrijenhoek, E.M.; Elimelech, M.; Tanaka, T.S.; Beuhler, M.D.

    1999-11-01

    Pilot-scale experiments were performed to investigate the effectiveness of enhanced coagulation in removing particles and trihalomethane (THM) precursors from two surface source waters: California State Project water and Colorado River water. The removal of suspended particles and natural organic matter at various ferric chloride doses and coagulation pHs was assessed through source water and filter effluent measurements of turbidity, particle count. UV{sub 254}, TOC, and THM formation potential. Overall, it was found that optimal removal of particles and THM precursors by enhanced coagulation with ferric chloride is obtained at high coagulant doses and low pH conditions. Generally, turbidity removal is more efficient and head loss is more moderate at ambient pH compared with pH 5.5. Additionally, filter effluent particle counts were found to be consistent with residual turbidity data. The removal of THM precursors by enhanced coagulation is significantly enhanced at pH 5.5 compared with ambient pH. The reduction in THM formation potential is consistent with the trends observed for the THM precursor removal data. Furthermore, specific UV absorbance was used to estimate the proportion of humic substances in the raw waters. Enhanced coagulation was found to be less effective for the source water with the lower specific UV absorbance.

  16. Nanophasic biodegradation enhances the durability and biocompatibility of magnesium alloys for the next-generation vascular stents

    NASA Astrophysics Data System (ADS)

    Mao, Lin; Shen, Li; Niu, Jialin; Zhang, Jian; Ding, Wenjiang; Wu, Yu; Fan, Rong; Yuan, Guangyin

    2013-09-01

    Biodegradable metal alloys emerge as a new class of biomaterials for tissue engineering and medical devices such as cardiovascular stents. Deploying biodegradable materials to fabricate stents not only obviates a second surgical intervention for implant removal but also circumvents the long-term foreign body effect of permanent implants. However, these materials for stents suffer from an un-controlled degradation rate, acute toxic responses, and rapid structural failure presumably due to a non-uniform, fast corrosion process. Here we report that highly uniform, nanophasic degradation is achieved in a new Mg alloy with unique interstitial alloying composition as the nominal formula Mg-2.5Nd-0.2Zn-0.4Zr (wt%, hereafter, denoted as JDBM). This material exhibits highly homogeneous nanophasic biodegradation patterns as compared to other biodegradable metal alloy materials. Consequently it has significantly reduced degradation rate determined by electrochemical characterization. The in vitro cytotoxicity test using human vascular endothelial cells indicates excellent biocompatibility and potentially minimal toxic effect on arterial vessel walls. Finally, we fabricated a cardiovascular stent using JDBM and performed in vivo long-term assessment via implantation of this stent in an animal model. The results confirmed the reduced degradation rate in vivo, excellent tissue compatibility and long-term structural and mechanical durability. Thus, this new Mg-alloy with highly uniform nanophasic biodegradation represents a major breakthrough in the field and a promising material for manufacturing the next generation biodegradable vascular stents.

  17. Possible Association of Ferrous Phosphates and Ferric Sulfates in S-rich Soil on Mars

    NASA Astrophysics Data System (ADS)

    Mao, J.; Schroeder, C.; Haderlein, S.

    2012-12-01

    NASA Mars Exploration Rover (MER) Spirit explored Gusev Crater to look for signs of ancient aqueous activity, assess past environmental conditions and suitability for life. Spirit excavated light-toned, S-rich soils at several locations. These are likely of hydrothermal, possibly fumarolic origin. At a location dubbed Paso Robles the light-toned soil was also rich in P - a signature from surrounding rock. While S is mainly bound in ferric hydrated sulfates [1], the mineralogy of P is ill-constrained [2]. P is a key element for life and its mineralogy constrains its availability. Ferrous phases observed in Paso Robles Mössbauer spectra may represent olivine and pyroxene from surrounding basaltic soil [1] or ferrous phosphate minerals [3]. Phosphate is well-known to complex and stabilize Fe 2+ against oxidation to Fe 3+ . Schröder et al. [3] proposed a formation pathway of ferrous phosphate/ferric sulfate associations: sulfuric acid reacts with basalt containing apatite, forming CaSO4 and phosphoric acid. The phosphoric and/or excess sulfuric acid reacts with olivine, forming Fe2+-phosphate and sulfate. The phosphate is less soluble and precipitates. Ferrous sulfate remains in solution and is oxidized as pH increases. To verify this pathway, we dissolved Fe2+-chloride and Na-phosphate salts in sulfuric acid inside an anoxic glovebox. The solution was titrated to pH 6 by adding NaOH when a first precipitate formed, which was ferrous phosphate according to Mössbauer spectroscopy (MB). At that point the solution was removed from the glovebox and allowed to evaporate in the presence of atmospheric oxygen, leading to the oxidation of Fe2+. The evaporation rate was controlled by keeping the suspensions at different temperatures; pH was monitored during the evaporation process. The final precipitates were analyzed by MB and X-Ray Fluorescence (XRF), comparable to MER MB and Alpha Particle X-ray Spectrometer instrument datasets, and complementary techniques such as X-ray diffraction. Fourier Transform Infrared spectroscopy measurements to compare to MER miniature thermal emission spectrometer data are planned. We observed differences depending on the heat source during evaporation. The closest match to Martian data on the basis of Mössbauer spectra was achieved with a suspension evaporated at 80°C on a hot plate, i.e. heated from below with a temperature gradient in the bottle. The Fe2+/FeT ratio matched, and ferrous phases were all phosphate. When heated in a water bath, i.e. without a temperature gradient in the bottle, Fe2+/FeT ratios increased and ferrous sulfates precipitated also. These results indicate that the Martian light-toned S-rich deposits formed by evaporation on the surface where temperature gradients would be expected rather than underground. They confirm that ferrous phosphate/ferric sulfate associations are possible on Mars and could be preserved in the oxygen-free Martian atmosphere. References: [1] Morris et al., J.Geophys. Res. 111 (2006) E02S13; [2] Ming et al., J. Geophys. Res. 111 (2006) E02S12; [3] Schröder et al., GSA Annual Meeting 2008, Paper No. 171-3.

  18. FpvA-Mediated Ferric Pyoverdine Uptake in Pseudomonas aeruginosa: Identification of Aromatic Residues in FpvA Implicated in Ferric Pyoverdine Binding and Transport

    Microsoft Academic Search

    Jiang-Sheng Shen; Valerie Geoffroy; Shadi Neshat; Zongchao Jia; Allison Meldrum; Jean-Marie Meyer; Keith Poole

    2005-01-01

    A number of aromatic residues were seen to cluster in the upper portion of the three-dimensional structure of the FpvA ferric pyoverdine receptor of Pseudomonas aeruginosa, reminiscent of the aromatic binding pocket for ferrichrome in the FhuA receptor of Escherichia coli. Alanine substitutions in three of these, W362, W391, and F795, markedly compromised ferric pyoverdine binding and transport, consistent with

  19. Organic matter mineralization with reduction of ferric iron in anaerobic sediments

    Microsoft Academic Search

    D. R. Lovley; E. J. P. Phillips

    1986-01-01

    The potential for ferric iron reduction with fermentable substrates, fermentation products, and complex organic matter as electron donors was investigated with sediments from freshwater and brackish water sites in the Potomac River Estuary. In enrichments with glucose and hematite, iron reduction was a minor pathway for electron flow, and fermentation products accumulated. The substitution of amorphous ferric oxyhydroxide for hematite

  20. The Ferric Reducing Ability of Plasma (FRAP) as a Measure of “Antioxidant Power”: The FRAP Assay

    Microsoft Academic Search

    Iris F. F. Benzie; J. J. Strain

    1996-01-01

    A simple, automated test measuring the ferric reducing ability of plasma, the FRAP assay, is presented as a novel method for assessing “antioxidant power.” Ferric to ferrous ion reduction at low pH causes a colored ferrous-tripyridyltriazine complex to form. FRAP values are obtained by comparing the absorbance change at 593 nm in test reaction mixtures with those containing ferrous ions

  1. Water Channel of Horseradish Peroxidase Studied by the Charge-Transfer Absorption Band of Ferric Heme

    E-print Network

    Sharp, Kim

    Water Channel of Horseradish Peroxidase Studied by the Charge-Transfer Absorption Band of Ferric The heme of horseradish peroxidase is buried in the protein, but a channel from the protein surface connects the aqueous solution to the heme site. Ferric horseradish peroxidase has an absorption band at 640

  2. Divergent roles for ferric ions in the biological activity of amidated and non-amidated gastrins

    Microsoft Academic Search

    J Pannequin; J-P Tantiongco; S Kovac; A Shulkes; G S Baldwin

    2004-01-01

    Amidated forms of the peptide hormone gastrin act via the cholecystokinin-2 receptor to stimulate gastric acid secretion, whereas non-amidated forms stimulate colonic mucosal proliferation via a novel, as yet uncharacterised, receptor. Nuclear magnetic resonance (NMR) and fluor- escence spectroscopic studies have revealed that glycine- extended gastrin17 bound two ferric ions, and that ferric ion binding was essential for biological activity.

  3. Biorecovery of copper from converter slags: Slags characterization and exploratory ferric leaching tests

    Microsoft Academic Search

    F. Carranza; R. Romero; A. Mazuelos; N. Iglesias; O. Forcat

    2009-01-01

    This paper studies the ferric sulphate leaching of converter slag (9% Cu) in order to recover Cu through a process in which bacteria regenerate the leaching agent. For this purpose, the effect of variables such as pulp density, ferric concentration, temperature and size particle have been investigated.As the Cu extraction is limited by the physical refractoriness of slag, a mild

  4. Electrodissolution of electrodeposited iron oxides

    SciTech Connect

    Isaacs, H.S.; Ryan, M.P. [Brookhaven National Lab., Upton, NY (United States); Kalonousky, D.N. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Materials Science; Virtanen, S. [Swiss Federal Inst. of Tech., Zurich (Switzerland). Inst. of Materials Chemistry and Corrosion

    1996-12-31

    Galvanostatic reduction of ferric oxide was studied in phosphate solutions over a range of pH values. The oxides were prepared on gold by anodic electrodeposition from dilute ferrous borate solution. With increased pH, the potential of the reduction arrests decreased and the charge associated with the arrest increased. A dependence of -60 mV/pH was observed except between pH 7.5 and 8.5 where the slope approximated -180 mV/pH. Above pH 7.5 the slope was consistent with the thermodynamic predicted slope of -180 mV/pH expected from reductive dissolution of ferric oxide forming soluble ferrous ions. At higher pH values, a slope of -60 mV/pH has been accounted for by oxide reduction to form a solid lower valent oxide.

  5. Niobium Uptake and Release by Bacterial Ferric Ion Binding Protein

    PubMed Central

    Shi, Yanbo; Harvey, Ian; Campopiano, Dominic; Sadler, Peter J.

    2010-01-01

    Ferric ion binding proteins (Fbps) transport FeIII across the periplasm and are vital for the virulence of many Gram negative bacteria. Iron(III) is tightly bound in a hinged binding cleft with octahedral coordination geometry involving binding to protein side chains (including tyrosinate residues) together with a synergistic anion such as phosphate. Niobium compounds are of interest for their potential biological activity, which has been little explored. We have studied the binding of cyclopentadienyl and nitrilotriacetato NbV complexes to the Fbp from Neisseria gonorrhoeae by UV-vis spectroscopy, chromatography, ICP-OES, mass spectrometry, and Nb K-edge X-ray absorption spectroscopy. These data suggest that NbV binds strongly to Fbp and that a dinuclear NbV centre can be readily accommodated in the interdomain binding cleft. The possibility of designing niobium-based antibiotics which block iron uptake by pathogenic bacteria is discussed. PMID:20445753

  6. Transcriptional regulation by Ferric Uptake Regulator (Fur) in pathogenic bacteria

    PubMed Central

    Troxell, Bryan; Hassan, Hosni M.

    2013-01-01

    In the ancient anaerobic environment, ferrous iron (Fe2+) was one of the first metal cofactors. Oxygenation of the ancient world challenged bacteria to acquire the insoluble ferric iron (Fe3+) and later to defend against reactive oxygen species (ROS) generated by the Fenton chemistry. To acquire Fe3+, bacteria produce low-molecular weight compounds, known as siderophores, which have extremely high affinity for Fe3+. However, during infection the host restricts iron from pathogens by producing iron- and siderophore-chelating proteins, by exporting iron from intracellular pathogen-containing compartments, and by limiting absorption of dietary iron. Ferric Uptake Regulator (Fur) is a transcription factor which utilizes Fe2+ as a corepressor and represses siderophore synthesis in pathogens. Fur, directly or indirectly, controls expression of enzymes that protect against ROS damage. Thus, the challenges of iron homeostasis and defense against ROS are addressed via Fur. Although the role of Fur as a repressor is well-documented, emerging evidence demonstrates that Fur can function as an activator. Fur activation can occur through three distinct mechanisms (1) indirectly via small RNAs, (2) binding at cis regulatory elements that enhance recruitment of the RNA polymerase holoenzyme (RNAP), and (3) functioning as an antirepressor by removing or blocking DNA binding of a repressor of transcription. In addition, Fur homologs control defense against peroxide stress (PerR) and control uptake of other metals such as zinc (Zur) and manganese (Mur) in pathogenic bacteria. Fur family members are important for virulence within bacterial pathogens since mutants of fur, perR, or zur exhibit reduced virulence within numerous animal and plant models of infection. This review focuses on the breadth of Fur regulation in pathogenic bacteria. PMID:24106689

  7. Synchrotron Characterization of Hydrogen and Ferric Iron in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Dyar, Melinda D.

    2003-01-01

    The hydrogen budget of the Martian interior is distributed among several phases: melts, hydrous minerals, and nominally anhydrous minerals like olivine, pyroxene, and garnet. All these phases are vulnerable to loss of hydrogen during shock, excavation and transport via the mechanism of dehydrogenation, in which the charge on the H protons is left behind as polarons on Fe atoms. Thus, both H and F(3x) must be analyzed in order to reconstruct hydrogen and oxygen fugacities on Mars. To date, SIMS data have elucidated D/H and H contents of hydrous phases in SNC meteorites, but anhydrous martian minerals have not been systematically examined for trace hydrogen. Ferric iron has been quantified using XANES in many marital phases, but integrated studies of both Fe(3x) and H on the same spots are really needed to address the H budget. Here, we measure and profile H and Fe(3x) abundances in and across individual grains of glass and silicates in Martian meteorites. We use the new technology of synchrotron microFI'lR spectroscopy to measure the hydrogen contents of hydrous and nominally anhydrous minerals in martian meteorites on 30-100 microns thick, doubly polished thin sections on spots down to 3 x 3 microns. Synchrotron microXANES was used to analyze Fe(3x) on the same scale, and complementary SIMS D/H data will be collected where possible, though at a slightly larger scale. Development of this combination of techniques is critical because future sample return missions will generate only microscopic samples for study. Results have been used to quantitatively assess the distribution of hydrogen and ferric iron among phases in the martian interior, which will better constrain the geodynamic processes of the interior, as well as the overall hydrogen and water budgets on Mars.

  8. Formation of Nanophase Iron in Lunar Soil Simulant for Use in ISRU Studies

    NASA Technical Reports Server (NTRS)

    Liu, Yang; Taylor, Lawrence A.; Hill, Eddy; Day, James D. M.

    2005-01-01

    For the prospective return of humans to the Moon and the extensive amount of premonitory studies necessary, large quantities of lunar soil simulants are required, for a myriad of purposes from construction/engineering purposes all the way to medical testing of its effects from ingestion by humans. And there is only a limited and precious quantity of lunar soil available on Earth (i.e., Apollo soils) - therefore, the immediate need for lunar soil simulants. Since the Apollo era, there have been several simulants; of these JSC-1 (Johnson Space Center) and MLS-1 (Minnesota Lunar Simulant) have been the most widely used. JSC-1 was produced from glassy volcanic tuff in order to approximate lunar soil geotechnical properties; whereas, MLS-1 approximates the chemistry of Apollo 11 high-Ti soil, 10084. Stocks of both simulants are depleted, but JSC-1 has recently gone back into production. The lunar soil simulant workshop, held at Marshall Space Flight Center in January 2005, identified the need to make new simulants for the special properties of lunar soil, such as nanophase iron (np-Fe(sup 0). Hill et al. (2005, this volume) showed the important role of microscale Fe(sup 0) in microwave processing of the lunar soil simulants JSC-1 and MLS-1. Lunar soil is formed by space weathering of lunar rocks (e.g., micrometeorite impact, cosmic particle bombardment). Glass generated during micrometeorite impact cements rock and mineral fragments together to form aggregates called agglutinates, and also produces vapor that is deposited and coats soil grains. Taylor et al. (2001) showed that the relative amount of impact glass in lunar soil increases with decreasing grain size and is the most abundant component in lunar dust (less than 20 micrometer fraction). Notably, the magnetic susceptibility of lunar soil also increases with the decreasing grain size, as a function of the amount of nanophase-sized Fe(sup 0) in impact-melt generated glass. Keller et al. (1997, 1999) also discovered the presence of abundant np-Fe(sup 0) particles in the glass patinas coating most soil particles. Therefore, the correlation of glass content and magnetic susceptibility can be explained by the presence of the np-Feo particles in glass: small particles contain relatively more np-Fe(sup 0) as glass coatings because the surface area versus mass ratio of the grain size is so increased. The magnetic properties of lunar soil are important in dust mitigation on the Moon (Taylor et al. 2005). Thus material simulating this property is important for testing mitigation methods using electromagnetic field. This np- Fe(sup 0) also produces a unique energy coupling to normal microwaves, such as present in kitchen microwave ovens. Effectively, a portion of lunar soil placed in a normal 2.45 GHz oven will melt at greater than 1200 C before your tea will boil at 100 C, a startling and new discovery reported by Taylor and Meek (2004, 2005). Several methods have been investigated in attempts to make nanophase-sized Feo dispersed within silicate glass; like in the lunar glass. We have been successful in synthesizing such a product and continue to improve on our recipe. We have performed extensive experimentation on this subject to date. Ultimately it will probably be necessary to add this np-Fe(sup 0) bearing silicate glass to lunar soil stimulant, like JSC-1, to actually produce the desired magnetic and microwave coupling properties for use in appropriate ISRU experimentation.

  9. Ferrous iron formation following the co-aggregation of ferric iron and the Alzheimer's disease peptide ?-amyloid (1–42)

    PubMed Central

    Everett, J.; Céspedes, E.; Shelford, L. R.; Exley, C.; Collingwood, J. F.; Dobson, J.; van der Laan, G.; Jenkins, C. A.; Arenholz, E.; Telling, N. D.

    2014-01-01

    For decades, a link between increased levels of iron and areas of Alzheimer's disease (AD) pathology has been recognized, including AD lesions comprised of the peptide ?-amyloid (A?). Despite many observations of this association, the relationship between A? and iron is poorly understood. Using X-ray microspectroscopy, X-ray absorption spectroscopy, electron microscopy and spectrophotometric iron(II) quantification techniques, we examine the interaction between A?(1–42) and synthetic iron(III), reminiscent of ferric iron stores in the brain. We report A? to be capable of accumulating iron(III) within amyloid aggregates, with this process resulting in A?-mediated reduction of iron(III) to a redox-active iron(II) phase. Additionally, we show that the presence of aluminium increases the reductive capacity of A?, enabling the redox cycling of the iron. These results demonstrate the ability of A? to accumulate iron, offering an explanation for previously observed local increases in iron concentration associated with AD lesions. Furthermore, the ability of iron to form redox-active iron phases from ferric precursors provides an origin both for the redox-active iron previously witnessed in AD tissue, and the increased levels of oxidative stress characteristic of AD. These interactions between A? and iron deliver valuable insights into the process of AD progression, which may ultimately provide targets for disease therapies. PMID:24671940

  10. DNA single strand breakage by H2O2 and ferric or cupric ions: its modulation by histidine.

    PubMed

    Tachon, P

    1990-01-01

    The role of histidine on DNA breakage induced by hydrogen peroxide (H2O2) and ferric ions or by H2O2 and cupric ions was studied on purified DNA. L-histidine slightly reduced DNA breakage by H2O2 and Fe3+ but greatly inhibited DNA breakage by H2O2 and Cu2+. However, only when histidine was present, the addition of EDTA to H2O2 and Fe3+ exhibited a bimodal dose response curve depending on the chelator metal ratio. The enhancing effect of histidine on the rate of DNA degradation by H2O2 was maximal at a chelator metal ratio between 0.2 and 0.5, and was specific for iron. When D-histidine replaced L-histidine, the same pattern of EDTA dose response curve was observed. Superoxide dismutase greatly inhibited the rate of DNA degradation induced by H2O2, Fe3+, EDTA and L-histidine involving the superoxide radical. These studies suggest that the enhancing effect of histidine on the rate of DNA degradation by H2O2 and Fe3+ is mediated by an oxidant which could be a ferrous-dioxygen-ferric chelate complex or a chelate-ferryl ion. PMID:2110924

  11. The Self-Assembled Nanophase Particle (SNAP) Process: A Nanoscience Approach to Coatings

    SciTech Connect

    Donley, Michael S.; Mantz, Robert A.; Khramov, A. N.; Balbyshev, Vsevolod; Kasten, Linda S.; Gaspar, Dan J.

    2003-09-15

    In the corrosion protection of aluminum-skinned aircraft, surface pretreatment and cleaning are critical steps in protecting aerospace alloys from corrosion. Our recent discovery of a revolutionary new method of forming functionalized silica nanoparticles in situ in an aqueous-based sol-gel process, and then crosslinking the nanoparticles to form a thin film, is an excellent example of a nanoscience approach to coatings. This coating method is called the self-assembled nanophase particle (SNAP) process. The SNAP coating process consists of three stages: (1) sol-gel processing; (2) SNAP solution mixing; (3) SNAP coating application and cure. Here, we report on key parameters in the ''sol-gel processing'' and the ''coating application and cure'' stages in the GPTMS/TMOS system. The SNAP process is discussed from the formation of the nanosized macromolecules to the coating application and curing process. The ''sol-gel processing'' stage involves hydrolysis and condensation reactions and is controlled by the solution pH and water content. Here, the molar ratio of water to hydrolysable silane is a key factor. SNAP solutions have been investigated by NMR, IR, light scattering, and GPC to identify molecular condensation structures formed as a function of aging time in the solution. In moderate pH and highwater content solutions, hydrolysis occurs rapidly and condensation kinetic conditions are optimized to generate nanophase siloxane macromolecules. In the ''SNAP solution mixing'' stage, crosslinking agents and additives are added to the solution, which is then applied to a substrate by dip-coating to form the SNAP coating. The chemical structure and morphology of the films have been characterized using X-ray diffraction (XRD), time-of-flight secondary ion mass spectrometry (TOF-SIMS) and atomic force microscopy (AFM). SNAP films are amorphous but exhibit nanostructured assembly of siloxane oligomers at a separation of about 1.8 nm as well as molecular level ordering of O-Si-O species. The surface analytical data indicate that the films retain the basic chemical arrangement of the siloxane macromolecules/oligomers and crosslinking process creates a network of siloxane oligomers tethered together. Results of these analyses are then used to construct a model of the SNAP coating.

  12. Evidence for the origin of layered deposits in Candor Chasma, Mars, from mineral composition and hydrologic modeling

    Microsoft Academic Search

    Scott Murchie; Leah Roach; Frank Seelos; Ralph Milliken; John Mustard; Raymond Arvidson; Sandra Wiseman; Kimberly Lichtenberg; Jeffrey Andrews-Hanna; Janice Bishop; Jean-Pierre Bibring; Mario Parente; Richard Morris

    2009-01-01

    New results from the Compact Reconnaissance Imaging Spectrometer for Mars and High Resolution Imaging Science Experiment and Context Imager cameras on Mars Reconnaissance Orbiter provide insights into the origin of interior layered deposits in Valles Marineris from analysis of a thick, well-exposed section in western Candor Chasma. Most of the deposit is dominated spectrally by nanophase ferric oxide like that

  13. A partial equilibrium model to characterize the precipitation of ferric ion during the leaching of chalcopyrite with ferric sulfate

    NASA Astrophysics Data System (ADS)

    Liddell, Knona C.; Bautista, Renato G.

    1983-03-01

    A partial equilibrium model has been developed and used to characterize the conditions under which precipitation of ferric ion occurs during the dump leaching of chalcopyrite ores. The precipitates which have been considered include amorphous Fe(OH)3, ?-FeOOH (goethite), and Na+, K+, Ag+, Pb2+, and H3O+ jarosites. Solution of the model equations makes possible the determination of the concentrations of the solution species during leaching of the mineral. The concentration product for Fe(OH)3 (am) and ?-FeOOH was calculated for changing solution concentrations and compared with the solubility product constants to determine when precipitation would be expected thermodynamically. The K+, Na+, Ag+, and Pb2+ concentrations that would be necessary to satisfy the solubility product constants for the corresponding jarosites were calculated for various initial concentrations and varying amounts of O2 consumption.

  14. Oxidation of diethylene glycol with ozone and modified Fenton processes

    Microsoft Academic Search

    Tuba Turan-Ertas; Mirat D. Gurol

    2002-01-01

    This paper describes a study of oxidation of diethylene glycol (DEG) by ozone and modified Fenton process (hydrogen peroxide and ferric salt mixture) in aqueous solution. Both oxidation processes were able to oxidize relatively high concentrations of DEG effectively. DEG reacted primarily through hydroxyl radical produced by decomposition of ozone, and about 3 mol of ozone were consumed per mole

  15. Nephrotoxicity and its prevention by vitamin E in ferric nitrilotriacetate-promoted lipid peroxidation.

    PubMed

    Okada, S; Hamazaki, S; Ebina, Y; Li, J L; Midorikawa, O

    1987-10-31

    Iron and aluminum complexes of nitrilotriacetic acid cause severe nephrotoxicity in Wistar rats. In addition, a high incidence of renal cell carcinoma is seen in ferric nitrilotriacetate-treated animals. The present study was performed to see if lipid peroxidation is involved in ferric nitrilotriacetate toxicity. Ferric nitrilotriacetate had more bleomycin-detectable 'free' iron than any ferric salt, while iron complexed with desferrioxamine or ferric chondroitin sulfate had none. The toxicity of ferric nitrilotriacetate in vivo was more pronounced in vitamin E-deficient rats. A thiobarbituric acid-reactive substance was present in the kidneys of vitamin E-deficient rats in amounts markedly elevated compared to vitamin E-sufficient, or vitamin E-supplemented rats. Non-complexed nitrilotriacetate or aluminum nitrilotriacetate did not produce any thiobarbituric acid-reactive substance in vitamin E-sufficient rats died by the 58th day of administration. We suggest that the iron-stimulated production of free radicals leading to lipid peroxidation is the major cause of ferric nitrilotriacetate-mediated renal toxicity. Vitamin E, a known scavenger of free radicals, is effective in protecting against this iron-induced toxicity. PMID:3663701

  16. Formation of ferric iron crusts in Quaternary sediments of Lake Baikal, Russia, and implications for paleoclimate

    USGS Publications Warehouse

    Deike, R.G.; Granina, L.; Callender, E.; McGee, J.J.

    1997-01-01

    Phosphate-bearing, ferric iron and siliceous crusts ranging in age from Recent to approximately 65,000 yr B.P. are observed in sediments of Lake Baikal. In younger sediments the crusts are at the base of a spectrum of secondary iron and manganese oxides that accumulate near the sediment/water interface in the zone of positive oxidation potential beneath an oxygenated water column. In areas where the average Quaternary sedimentation rates have been slow (e.g. 0.026 mm/yr), the crusts are more common, and span a wider range of ages. No crusts have been found where the Quaternary sedimentation mode has been deltaic and rapid (0.15 mm/yr). Independent core correlation based on magnetic properties of the sediment suggests that crusts can be correlated over most of Academician Ridge, an area that is particularly sensitive to climatic events affecting the concentration of suspended sediment. These crusts may be indicative of periods of low suspended sediment concentration, which occur during sustained transitions from glacial periods of high detrital input, to interglacial periods of high diatom sedimentation. The crusts are dominated by iron-rich and siliceous amorphous mineral phases, with an FeO:SiO2 by weight of 3:1. Regardless of age or location in the lake the Fe phase always includes Ca, P and Mn. Extensive microprobe data for these four elements recast as normalized elemental weight percent reveal linear trends of Ca:P and Fe:P. With increasing P, Ca also increases such that the two elements maintain a linear relationship passing very close to the origin and with a mean molar Ca:P=0.3 (too low for well-characterized apatite). Conversely, with increasing P, Fe decreases (mean molar Fe:P=3.4). There is no correlation between Mn and P. Molar Fe:P ratios for vivianite (an Fe(II) phosphate mineral observed in sediments closely below some crusts) are clustered around a stoichiometric composition. The covariant increase in Ca:P and the corresponding decrease in Fe:P may be explained by: (1) coupled adsorption of aqueous Ca and P by a colloidal ferric hydrous oxide; (2) loss of Fe from a Ca-P-Fe phase; or (3) oxidation of vivianite to a metastable mineral phase that gradually loses Ca and gains Fe. The first explanation is favored, because there is no petrographic evidence for either the existence of an originating Ca-P-Fe phase, or, for the oxidation of vivianite. Further, it is suggested that by continually equalizing surface charge, Ca allows more phosphate to be adsorbed leading to thicker crusts and longer preservation after burial.

  17. Ferric uptake regulator-dependent antinitrosative defenses in Salmonella enterica serovar Typhimurium pathogenesis.

    PubMed

    Husain, Maroof; Jones-Carson, Jessica; Liu, Lin; Song, Miryoung; Saah, J Royden; Troxell, Bryan; Mendoza, Mary; Hassan, Hosni; Vázquez-Torres, Andrés

    2014-01-01

    Herein we report an important role for the ferric uptake regulator (Fur) in the resistance of Salmonella enterica serovar Typhimurium to the reactive nitrogen species produced by inducible nitric oxide (NO) synthase in an NRAMP1(r) murine model of acute systemic infection. The expression of fur protected Salmonella grown under normoxic and hypoxic conditions against the bacteriostatic activity of NO. The hypersusceptibility of fur-deficient Salmonella to the cytotoxic actions of NO coincides with a marked repression of respiratory activity and the reduced ability of the bacteria to detoxify NO. A fur mutant Salmonella strain contained reduced levels of the terminal quinol oxidases of the electron transport chain. Addition of the heme precursor ?-aminolevulinic acid restored the cytochrome content, respiratory activity, NO consumption, and wild-type growth in bacteria undergoing nitrosative stress. The innate antinitrosative defenses regulated by Fur added to the adaptive response associated with the NO-detoxifying activity of the flavohemoprotein Hmp. Our investigations indicate that, in addition to playing a critical role in iron homeostasis, Fur is an important antinitrosative determinant of Salmonella pathogenesis. PMID:24166960

  18. The effect on structural and solvent water molecules of substrate binding to ferric horseradish peroxidase.

    PubMed

    Simpson, Niall; Adamczyk, Katrin; Hithell, Gordon; Shaw, Daniel J; Greetham, Gregory M; Towrie, Michael; Parker, Anthony W; Hunt, Neil T

    2015-01-01

    Ultrafast, multi-dimensional infrared spectroscopy, in the form of 2D-IR and pump-probe measurements, has been employed to investigate the effect of substrate binding on the structural dynamics of the horseradish peroxidase (HRP) enzyme. Using nitric oxide bound to the ferric haem of HRP as a sensitive probe of local dynamics, we report measurements of the frequency fluctuations (spectral diffusion) and vibrational lifetime of the NO stretching mode with benzohydroxamic acid (BHA) located in the substrate-binding position at the periphery of the haem pocket, in both D2O and H2O solvents. The results reveal that, with BHA bound to the enzyme, the local structural dynamics are insensitive to H/D exchange. These results are in stark contrast to those found in studies of the substrate-free enzyme, which demonstrated that the local chemical and dynamic environment of the haem ligand is influenced by water molecules. In light of the large changes in solvent accessibility caused by substrate binding, we discuss the potential for varying roles for the solvent in the haem pocket of HRP at different stages along the reaction coordinate of the enzymatic mechanism. PMID:25605054

  19. Mössbauer and infrared spectroscopy as a diagnostic tool for the characterization of ferric tannates

    NASA Astrophysics Data System (ADS)

    Jaén, Juan A.; Navarro, César

    2009-07-01

    Fourier transform infrared spectroscopy and Mössbauer spectroscopy are use for the characterization and qualitative analysis of hydrolysable and condensed tannates. The two classes of tannates may be differentiated from the characteristic IR pattern. Mössbauer proof that a mixture of mono- and bis-type ferric tannate complexes, and an iron(II)-tannin complex are obtained from the interaction of hydrolysable tannins (tannic acid and chestnut tannin) and condensed tannins (mimosa and quebracho) with a ferric nitrate solution. At pH 7, a partially hydrolyzed ferric tannate complex was also obtained.

  20. Mechanistic insights on the ortho-hydroxylation of aromatic compounds by non-heme iron complex: a computational case study on the comparative oxidative ability of ferric-hydroperoxo and high-valent Fe(IV)?O and Fe(V)?O intermediates.

    PubMed

    Ansari, Azaj; Kaushik, Abhishek; Rajaraman, Gopalan

    2013-03-20

    ortho-Hydroxylation of aromatic compounds by non-heme Fe complexes has been extensively studied in recent years by several research groups. The nature of the proposed oxidant varies from Fe(III)-OOH to high-valent Fe(IV)?O and Fe(V)?O species, and no definitive consensus has emerged. In this comprehensive study, we have investigated the ortho-hydroxylation of aromatic compounds by an iron complex using hybrid density functional theory incorporating dispersion effects. Three different oxidants, Fe(III)-OOH, Fe(IV)?O, and Fe(V)?O, and two different pathways, H-abstraction and electrophilic attack, have been considered to test the oxidative ability of different oxidants and to underpin the exact mechanism of this regiospecific reaction. By mapping the potential energy surface of each oxidant, our calculations categorize Fe(III)-OOH as a sluggish oxidant, as both proximal and distal oxygen atoms of this species have prohibitively high barriers to carry out the aromatic hydroxylation. This is in agreement to the experimental observation where Fe(III)-OOH is found not to directly attack the aromatic ring. A novel mechanism for the explicit generation of non-heme Fe(IV)?O and Fe(V)?O from isomeric forms of Fe(III)-OOH has been proposed where the O···O bond is found to cleave via homolytic (Fe(IV)?O) or heterolytic (Fe(V)?O) fashion exclusively. Apart from having favorable formation energies, the Fe(V)?O species also has a lower barrier height compared to the corresponding Fe(IV)?O species for the aromatic ortho-hydroxylation reaction. The transient Fe(V)?O prefers electrophilic attack on the benzene ring rather than the usual aromatic C-H activation step. A large thermodynamic drive for the formation of a radical intermediate is encountered in the mechanistic scene, and this intermediate substantially diminishes the energy barrier required for C-H activation by the Fe(V)?O species. Further spin density distribution and the frontier orbitals of the computed species suggest that the Fe(IV)?O species has a substantial barrier height for this reaction, as the substrate is coordinated to the metal atoms. This coordination restricts the C-H activation step by Fe(IV)?O species to proceed via the ?-type pathway, and thus the usual energy lowering due to the low-lying quintet state is not observed here. PMID:23373840

  1. Aggregation in complex triacylglycerol oils: coarse-grained models, nanophase separation, and predicted x-ray intensities

    NASA Astrophysics Data System (ADS)

    Quinn, Bonnie; Peyronel, Fernanda; Gordon, Tyler; Marangoni, Alejandro; Hanna, Charles B.; Pink, David A.

    2014-11-01

    Triacylglycerols (TAGs) are biologically important molecules which form crystalline nanoplatelets (CNPs) and, ultimately, fat crystal networks in edible oils. Characterizing the self-assembled hierarchies of these networks is important to understanding their functionality and oil binding capacity. We have modelled CNPs in multicomponent oils and studied their aggregation. The oil comprises (a) a liquid componentt, and (b) components which phase separately on a nano-scale (nano-phase separation) to coat the surfaces of the CNPs impenetrably, either isotropically or anisotropically, with either liquid-like coatings or crystallites, forming a coating of thickness ?. We modelled three cases: (i) liquid–liquid nano-phase separation, (ii) solid–liquid nano-phase separation, with CNPs coated isotropically, and (iii) CNPs coated anisotropically. The models were applied to mixes of tristearin and triolein with fully hydrogenated canola oil, shea butter with high oleic sunflower oil, and cotton seed oil. We performed Monte Carlo simulations, computed structure functions and concluded: (1) three regimes arose: (a) thin coating regime, ? \\lt 0.0701 u (b) transition regime, 0.0701 u?slant ? ?slant 0.0916 u and (c) thick coating regime, ? \\gt 0.0916 u . (arbitrary units, u) (2) The thin coating regime exhibits 1D TAGwoods, which aggregate, via DLCA/RLCA, into fractal structures which are uniformly distributed in space. (3) In the thick coating regime, for an isotropic coating, TAGwoods are not formed and coated CNPs will not aggregate but will be uniformly distributed in space. For anisotropic coating, TAGwoods can be formed and might form 1D strings but will not form DLCA/RLCA clusters. (4) The regimes are, approximately: thin coating, 0\\lt ? \\lt 7.0 \\text{nm} transition regime, 7.0\\lt? \\lt 9.2 \\text{nm} and thick coating, ? \\gt 9.2 \\text{nm} (5) The minimum minority TAG concentration required to undergo nano-phase separation is, approximately, 0.29% (thin coatings) and 0.94% (thick coatings). Minority components can have substantial effects upon aggregation for concentrations less than 1%.

  2. Ferric and Possible Ferrous Sulfates in the Northern Mawrth Vallis Region of Mars

    NASA Astrophysics Data System (ADS)

    Farrand, W. H.; Glotch, T. D.; Horgan, B.

    2014-07-01

    Some CRISM scenes in the northern Mawrth Vallis region have patches, occurring on top of the Al phyllosilicate unit, with spectral features consistent with ferrous, or mixed ferric/ferrous, sulfate minerals indicating the action of acidic waters.

  3. Ferrous versus Ferric Oral Iron Formulations for the Treatment of Iron Deficiency: A Clinical Overview

    PubMed Central

    Santiago, Palacios

    2012-01-01

    Iron deficiency anaemia represents a major public health problem, particularly in infants, young children, pregnant women, and females with heavy menses. Oral iron supplementation is a cheap, safe, and effective means of increasing haemoglobin levels and restoring iron stores to prevent and correct iron deficiency. Many preparations are available, varying widely in dosage, formulation (quick or prolonged release), and chemical state (ferrous or ferric form). The debate over the advantages of ferrous versus ferric formulations is ongoing. In this literature review, the tolerability and efficacy of ferrous versus ferric iron formulations are evaluated. We focused on studies comparing ferrous sulphate preparations with ferric iron polymaltose complex preparations, the two predominant forms of iron used. Current data show that slow-release ferrous sulphate preparations remain the established and standard treatment of iron deficiency, irrespective of the indication, given their good bioavailability, efficacy, and acceptable tolerability demonstrated in several large clinical studies. PMID:22654638

  4. Ferrous versus ferric oral iron formulations for the treatment of iron deficiency: a clinical overview.

    PubMed

    Santiago, Palacios

    2012-01-01

    Iron deficiency anaemia represents a major public health problem, particularly in infants, young children, pregnant women, and females with heavy menses. Oral iron supplementation is a cheap, safe, and effective means of increasing haemoglobin levels and restoring iron stores to prevent and correct iron deficiency. Many preparations are available, varying widely in dosage, formulation (quick or prolonged release), and chemical state (ferrous or ferric form). The debate over the advantages of ferrous versus ferric formulations is ongoing. In this literature review, the tolerability and efficacy of ferrous versus ferric iron formulations are evaluated. We focused on studies comparing ferrous sulphate preparations with ferric iron polymaltose complex preparations, the two predominant forms of iron used. Current data show that slow-release ferrous sulphate preparations remain the established and standard treatment of iron deficiency, irrespective of the indication, given their good bioavailability, efficacy, and acceptable tolerability demonstrated in several large clinical studies. PMID:22654638

  5. Exfoliation of Hexagonal Boron Nitride via Ferric Chloride Intercalation

    NASA Technical Reports Server (NTRS)

    Hung, Ching-cheh; Hurst, Janet; Santiago, Diana; Rogers, Richard B.

    2014-01-01

    Sodium fluoride (NaF) was used as an activation agent to successfully intercalate ferric chloride (FeCl3) into hexagonal boron nitride (hBN). This reaction caused the hBN mass to increase by approx.100 percent, the lattice parameter c to decrease from 6.6585 to between 6.6565 and 6.6569 ?, the x-ray diffraction (XRD) (002) peak to widen from 0.01deg to 0.05deg of the full width half maximum value, the Fourier transform infrared (FTIR) spectrum's broad band (1277/cm peak) to change shape, and new FTIR bands to emerge at 3700 to 2700 and 1600/cm. This indicates hBN's structural and chemical properties are significantly changed. The intercalated product was hygroscopic and interacted with moisture in the air to cause further structural and chemical changes (from XRD and FTIR). During a 24-h hold at room temperature in air with 100 percent relative humidity, the mass increased another 141 percent. The intercalated product, hydrated or not, can be heated to 750 C in air to cause exfoliation. Exfoliation becomes significant after two intercalation-air heating cycles, when 20-nm nanosheets are commonly found. Structural and chemical changes indicated by XRD and FTIR data were nearly reversed after the product was placed in hydrochloric acid (HCl), resulting in purified, exfoliated, thin hBN products.

  6. Enhanced organic pollutant removal influenced by activated-ferric-sludge.

    PubMed

    Xu, G R; Tang, J H; Li, G B; Spinosa, L

    2014-01-01

    The primary goal of this study was to compare the pollutant removal efficiency of the reactivated activated-ferric-sludge (AFS) with that of the activated sludge (AS). Most tested organic pollutants were preferably removed by reactivated AFS. The optimal reactivated conditions for AFS were a reactivation time of 3 h, pH of 5-9, AFS dose of 5 g/L and dissolved oxygen of 2-6 mg/L. The results revealed a positive correlation between microbial activity and the removal efficiency of organic pollutants, with a higher microbial activity being associated with a better removal efficiency of organic pollutants. Additionally, variations in extracellular polymeric substances were found to be crucial to the microbial activity and adsorption capacity of reactivated AFS. After reactivation, reactivated AFS was superior to AS for the removal ofmost pollutants. Finally, the mechanism of AFS reactivation was investigated. Overall, the results of the present study demonstrate that reactivated AFS has the potential for widespread application in the removal of organic pollutants during the wastewater treatment process. PMID:25145208

  7. Iron fortification of flour with a complex ferric orthophosphate

    SciTech Connect

    Hallberg, L.; Rossander-Hulthen, L.; Gramatkovski, E.

    1989-07-01

    The unexpectedly low bioavailability in humans of elemental iron powder prompted us to search for other Fe compounds suitable for Fe fortification of flour that fulfill the two requirements of insolubility in water (due to high water content of flour) and good bioavailability in humans. Systematic studies of compatibility, solubility, and bioavailability led to this study of a microcrystalline complex ferric orthophosphate (CFOP), Fe/sub 3/H/sub 8/(NH/sub 4/)-(PO/sub 4/)6.6H/sub 2/O, a well-defined compound. This compound was labeled with /sup 59/Fe, and the native Fe in meals was labeled with /sup 55/FeCl3. The ratio of absorbed /sup 59/Fe to absorbed /sup 55/Fe is a direct measure of the fraction of CFOP that joins the nonheme Fe pool and that is made potentially available for absorption. The relative bioavailability of CFOP varied from 30% to 60% when labeled wheat rolls were served with different meals. The CFOP meets practical requirements of an Fe fortificant for flour well, with regard to both compatibility and bioavailability in humans.

  8. Cryogenic photolysis of activated bleomycin to ferric bleomycin.

    PubMed

    Burger, Richard M; Usov, Oleg M; Grigoryants, Vladimir M; Scholes, Charles P

    2006-10-19

    Activated bleomycin (ABLM) is a drug--Fe(III)-hydroperoxide complex kinetically competent in DNA attack (via H4' abstraction). This intermediate is relatively stable, but its spontaneous conversion to ferric bleomycin (Fe(III).BLM) is poorly characterized because no observable intermediate product accumulates. Light was shown to trigger ABLM attack on DNA in liquid at -30 degrees C, so ABLM was irradiated (at its 350 nm ligand-to-metal charge-transfer transition) at 77 K to stabilize possible intermediates. ABLM photolysis (quantum yield, Phi = 0.005) generates two kinds of product: Fe(III).BLM (with no detectable intermediate) and one or more minor (1-2%) radical O-Fe-BLM byproduct, photostable at 77 K. Adding DNA, even without its target H4', increases the quantum yield of ABLM conversion >10-fold while suppressing the observed radical yield. Since cryogenic solid-phase reactions can entail only constrained local rearrangement, the reaction(s) converting ABLM to Fe(III).BLM must be similarly constrained. PMID:17034262

  9. Ferric Citrate Hydrate for the Treatment of Hyperphosphatemia in Nondialysis-Dependent CKD

    PubMed Central

    Hirakata, Hideki; Akiba, Takashi; Fukagawa, Masafumi; Nakayama, Masaaki; Sawada, Kenichi; Kumagai, Yuji; Block, Geoffrey A.

    2014-01-01

    Background and objectives Ferric citrate hydrate is a novel iron-based phosphate binder being developed for hyperphosphatemia in patients with CKD. Design, setting, participants, & measurements A phase 3, multicenter, randomized, double blind, placebo-controlled study investigated the efficacy and safety of ferric citrate hydrate in nondialysis-dependent patients with CKD. Starting in April of 2011, 90 CKD patients (eGFR=9.21±5.72 ml/min per 1.73 m2) with a serum phosphate?5.0 mg/dl were randomized 2:1 to ferric citrate hydrate or placebo for 12 weeks. The primary end point was change in serum phosphate from baseline to the end of treatment. Secondary end points included the percentage of patients achieving target serum phosphate levels (2.5–4.5 mg/dl) and change in fibroblast growth factor-23 at the end of treatment. Results The mean change in serum phosphate was ?1.29 mg/dl (95% confidence interval, ?1.63 to ?0.96 mg/dl) in the ferric citrate hydrate group and 0.06 mg/dl (95% confidence interval, ?0.20 to 0.31 mg/dl) in the placebo group (P<0.001 for difference between groups). The percentage of patients achieving target serum phosphate levels was 64.9% in the ferric citrate hydrate group and 6.9% in the placebo group (P<0.001). Fibroblast growth factor-23 concentrations were significantly lower in patients treated with ferric citrate hydrate versus placebo (change from baseline [median], ?142.0 versus 67.0 pg/ml; P<0.001). Ferric citrate hydrate significantly increased serum iron, ferritin, and transferrin saturation compared with placebo (P=0.001 or P<0.001). Five patients discontinued active treatment because of treatment-emergent adverse events with ferric citrate hydrate treatment versus one patient with placebo. Overall, adverse drug reactions were similar in patients receiving ferric citrate hydrate or placebo, with gastrointestinal disorders occurring in 30.0% of ferric citrate hydrate patients and 26.7% of patients receiving placebo. Conclusion In patients with nondialysis-dependent CKD, 12-week treatment with ferric citrate hydrate resulted in significant reductions in serum phosphate and fibroblast growth factor-23 while simultaneously increasing serum iron parameters. PMID:24408120

  10. Analysis of a ferric leghemoglobin reductase from cowpea ( Vigna unguiculata) root nodules

    Microsoft Academic Search

    Peng Luan; Elena Aréchaga-Ocampo; Gautam Sarath; Raúl Arredondo-Peter; Robert V. Klucas

    2000-01-01

    Ferric leghemoglobin reductase (FLbR), an enzyme reducing ferric leghemoglobin (Lb) to ferrous Lb, was purified from cowpea (Vigna unguiculata) root nodules by sequential chromatography on hydroxylapatite followed by Mono-Q HR5\\/5 FPLC and Sephacryl S-200 gel filtration. The purified cowpea FLbR had a specific activity of 216 nmol Lb2+O2 formed min?1 mg?1 of enzyme for cowpea Lb3+ and a specific activity

  11. Total X-ray scattering, EXAFS, and Mössbauer spectroscopy analyses of amorphous ferric arsenate and amorphous ferric phosphate

    NASA Astrophysics Data System (ADS)

    Mikutta, Christian; Schröder, Christian; Marc Michel, F.

    2014-09-01

    Amorphous ferric arsenate (AFA, FeAsO4·xH2O) is an important As precipitate in a range of oxic As-rich environments, especially acidic sulfide-bearing mine wastes. Its structure has been proposed to consist of small polymers of single corner-sharing FeO6 octahedra (rFe-Fe ?3.6 Å) to which arsenate is attached as a monodentate binuclear 2C complex (‘chain model’). Here, we analyzed the structure of AFA and analogously prepared amorphous ferric phosphates (AFP, FePO4·xH2O) by a combination of high-energy total X-ray scattering, Fe K-edge X-ray absorption spectroscopy, and 57Fe Mössbauer spectroscopy. Pair distribution function (PDF) analysis of total X-ray scattering data revealed that the coherently scattering domain size of AFA and AFP is about 8 Å. The PDFs of AFA lacked Fe-Fe pair correlations at r ?3.6 Å indicative of single corner-sharing FeO6 octahedra, which strongly supports a local scorodite (FeAsO4·2H2O) structure. Likewise, the PDFs and Fe K-edge extended X-ray absorption fine structure data of AFP were consistent with a local strengite (FePO4·2H2O) structure of isolated FeO6 octahedra being corner-linked to PO4 tetrahedra (rFe-P = 3.25(1) Å). Mössbauer spectroscopy analyses of AFA and AFP indicated a strong superparamagnetism. While AFA only showed a weak onset of magnetic hyperfine splitting at 5 K, magnetic ordering of AFP was completely absent at this temperature. Mössbauer spectroscopy may thus offer a convenient way to identify and quantify AFA and AFP in mineral mixtures containing poorly crystalline Fe(III)-oxyhydroxides. In summary, our results imply a close structural relationship between AFA and AFP and suggest that these amorphous materials serve as templates for the formation of scorodite and strengite (phosphosiderite) in strongly acidic low-temperature environments.

  12. Ferric-pyoverdine recognition by Fpv outer membrane proteins of Pseudomonas protegens Pf-5.

    PubMed

    Hartney, Sierra L; Mazurier, Sylvie; Girard, Maëva K; Mehnaz, Samina; Davis, Edward W; Gross, Harald; Lemanceau, Philippe; Loper, Joyce E

    2013-02-01

    The soil bacterium Pseudomonas protegens Pf-5 (previously called P. fluorescens Pf-5) produces two siderophores, enantio-pyochelin and a compound in the large and diverse pyoverdine family. Using high-resolution mass spectroscopy, we determined the structure of the pyoverdine produced by Pf-5. In addition to producing its own siderophores, Pf-5 also utilizes ferric complexes of some pyoverdines produced by other strains of Pseudomonas spp. as sources of iron. Previously, phylogenetic analysis of the 45 TonB-dependent outer membrane proteins in Pf-5 indicated that six are in a well-supported clade with ferric-pyoverdine receptors (Fpvs) from other Pseudomonas spp. We used a combination of phylogenetics, bioinformatics, mutagenesis, pyoverdine structural determinations, and cross-feeding bioassays to assign specific ferric-pyoverdine substrates to each of the six Fpvs of Pf-5. We identified at least one ferric-pyoverdine that was taken up by each of the six Fpvs of Pf-5. Functional redundancy of the Pf-5 Fpvs was also apparent, with some ferric-pyoverdines taken up by all mutants with a single Fpv deletion but not by a mutant having deletions in two of the Fpv-encoding genes. Finally, we demonstrated that phylogenetically related Fpvs take up ferric complexes of structurally related pyoverdines, thereby establishing structure-function relationships that can be employed in the future to predict the pyoverdine substrates of Fpvs in other Pseudomonas spp. PMID:23222724

  13. Liposome as a delivery system for carotenoids: comparative antioxidant activity of carotenoids as measured by ferric reducing antioxidant power, DPPH assay and lipid peroxidation.

    PubMed

    Tan, Chen; Xue, Jin; Abbas, Shabbar; Feng, Biao; Zhang, Xiaoming; Xia, Shuqin

    2014-07-16

    This study was conducted to understand how carotenoids exerted antioxidant activity after encapsulation in a liposome delivery system, for food application. Three assays were selected to achieve a wide range of technical principles, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, ferric reducing antioxidant powder (FRAP), and lipid peroxidation inhibition capacity (LPIC) during liposome preparation, auto-oxidation, or when induced by ferric iron/ascorbate. The antioxidant activity of carotenoids was measured either after they were mixed with preformed liposomes or after their incorporation into the liposomal system. Whatever the antioxidant model was, carotenoids displayed different antioxidant activities in suspension and in liposomes. The encapsulation could enhance the DPPH scavenging and FRAP activities of carotenoids. The strongest antioxidant activity was observed with lutein, followed by ?-carotene, lycopene, and canthaxanthin. Furthermore, lipid peroxidation assay revealed a mutually protective relationship: the incorporation of either lutein or ?-carotene not only exerts strong LPIC, but also protects them against pro-oxidation elements; however, the LPIC of lycopene and canthaxanthin on liposomes was weak or a pro-oxidation effect even appeared, concomitantly leading to the considerable depletion of these encapsulated carotenoids. The antioxidant activity of carotenoids after liposome encapsulation was not only related to their chemical reactivity, but also to their incorporation efficiencies into liposomal membrane and modulating effects on the membrane properties. PMID:24745755

  14. Modeling the Nanophase Structural Dynamics of Phenylated Sulfonated Poly Ether Ether Ketone Ketone (Ph-SPEEKK) Membranes as a Function of Hydration

    Microsoft Academic Search

    Roberto D. Lins; Ramaswami Devanathan; Michel Dupuis

    2011-01-01

    Solvated phenylated sulfonated poly ether ether ketone ketone (Ph-SPEEKK) membranes in the presence of hydronium ions were modeled by classical molecular dynamics simulations. The characterization of the nanophase structure and dynamics of such membranes was carried out as a function of the water content lambda, where lambda is the number of water molecules per sulfonate group, for lambda values of

  15. Ferrous iron oxidation by anoxygenic phototrophic bacteria

    Microsoft Academic Search

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

    1993-01-01

    NATURAL oxidation of ferrous to ferric iron by bacteria such as Thiobacillus ferrooxidans or Gallionella ferruginea1, or by chemical oxidation2,3 has previously been thought always to involve molecular oxygen as the electron acceptor. Anoxic photochemical reactions4-6 or a photobiological process involving two photosystems7-9 have also been discussed as mechanisms of ferrous iron oxidation. The knowledge of such processes has implications

  16. Nanophase cobalt, nickel and zinc ferrites: synchrotron XAS study on the crystallite size dependence of metal distribution.

    PubMed

    Nordhei, Camilla; Ramstad, Astrid Lund; Nicholson, David G

    2008-02-21

    Nanophase cobalt, nickel and zinc ferrites, in which the crystallites are in the size range 4-25 nm, were synthesised by coprecipitation and subsequent annealing. X-Ray absorption spectroscopy using synchrotron radiation (supported by X-ray powder diffraction) was used to study the effects of particle size on the distributions of the metal atoms over the tetrahedral and octahedral sites of the spinel structure. Deviations from the bulk structure were found which are attributed to the significant influence of the surface on very small particles. Like the bulk material, nickel ferrite is an inverse spinel in the nanoregime, although the population of metals on the octahedral sites increases with decreasing particle size. Cobalt ferrite and zinc ferrite take the inverse and normal forms of the spinel structure respectively, but within the nanoregime both systems show similar trends in being partially inverted. Further, in zinc ferrite, unlike the normal bulk structure, the nanophase system involves mixed coordinations of zinc(ii) and iron(iii) consistent with increasing partial inversion with size. PMID:18259645

  17. Si quantum dots embedded in an amorphous SiC matrix: nanophase control by non-equilibrium plasma hydrogenation.

    PubMed

    Cheng, Qijin; Tam, Eugene; Xu, Shuyan; Ostrikov, Kostya Ken

    2010-04-01

    Nanophase nc-Si/a-SiC films that contain Si quantum dots (QDs) embedded in an amorphous SiC matrix were deposited on single-crystal silicon substrates using inductively coupled plasma-assisted chemical vapor deposition from the reactive silane and methane precursor gases diluted with hydrogen at a substrate temperature of 200 degrees C. The effect of the hydrogen dilution ratio X (X is defined as the flow rate ratio of hydrogen-to-silane plus methane gases), ranging from 0 to 10.0, on the morphological, structural, and compositional properties of the deposited films, is extensively and systematically studied by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier-transform infrared absorption spectroscopy, and X-ray photoelectron spectroscopy. Effective nanophase segregation at a low hydrogen dilution ratio of 4.0 leads to the formation of highly uniform Si QDs embedded in the amorphous SiC matrix. It is also shown that with the increase of X, the crystallinity degree and the crystallite size increase while the carbon content and the growth rate decrease. The obtained experimental results are explained in terms of the effect of hydrogen dilution on the nucleation and growth processes of the Si QDs in the high-density plasmas. These results are highly relevant to the development of next-generation photovoltaic solar cells, light-emitting diodes, thin-film transistors, and other applications. PMID:20644764

  18. [Study of infrared spectra of polyaluminum ferric chloride].

    PubMed

    Zhang, Xin-hua; Zhou, Li-yun; Tang, Min

    2002-02-01

    Mid-IR spectra of polyaluminum ferric chloride (PAFC) with different Al/Fe molar ratio were studied by Fourier transform infrared spectroscopy. Some vibration bands were assigned. In the range of Al/Fe molar ratio < 3:7 and > 6:4, the delta bending vibration frequencies at 850-880 cm-1 of [formula: see text] and 930-970 cm-1 of [formula: see text] in PAFC vs Al/Fe molar ratio are linearly relalional. It shows that Fe(III) and Al(III) were taken place each other in [formula: see text] and [formula: see text], and these were the evidences for the presence of [formula: see text]. When Al/Fe molar ratio was close, [formula: see text] and [formula: see text] Al bulk bending vibration bands at 680 cm-1 and 625 cm-1 respectively became an overlapped and broad band at 640 cm-1. Correspondingly, the [formula: see text] and [formula: see text] delta bending vibration bands were weak markedly or even disappear. And these were the evidences for the presence of co-aggragation of Fe(III) and Al(III) hydroxyl polymers (Aluminous ferrihydrite). Intensity and frequency change of H-OH delta vibrations bands at 1,610-1,630 cm-1 vs Al/Fe molar ratio show: the amounts of coordinating water in Al-Fe hydroxyl co-aggragation compounds of PAFC are the highest and no longer change, as well as, the force of banding of coordinating water with center atoms is increasing when Al/Fe molar ratio > 6:4. These suggested that there are species structural Al-Fe hydroxyl co-aggragatin compounds and this is one of the causes that stability of PAFC solution can be keeped for a long time. PMID:12940022

  19. Bioavailability of iron from oral ferric polymaltose in humans.

    PubMed

    Nielsen, P; Gabbe, E E; Fischer, R; Heinrich, H C

    1994-06-01

    The bioavailability or iron from iron(III)hydroxide polymaltose complex (ferric polymaltose, Fe-PM) was studied in human volunteers with normal or depleted iron stores as well as in patients with iron deficiency anemia. From an oral iron dose of 100 mg neutron activated Fe-PM, starved subjects with depleted iron stores absorbed significantly less (p < 0.003) 59Fe (3.91 +/- 2.24%, mean +/- SD) as compared to the reference, aqueous 59Fe(II) ascorbate solution (13.8 +/- 6.19%). Using non-radiolabeled, commercial Fe-PM no postabsorptive serum iron increase was found after oral Fe-PM (100 mg Fe dosage) in a group of 7 patients with haemorrhagic or posthaemorrhagic iron deficiency anemia. In addition, almost no haemoglobin increase was observed in 9 patients during a 4-weeks treatment period when given Fe-PM (100-300 mg Fe/d) on empty stomach, whereas subsequent treatment with ferrous sulfate (100-200 mg Fe/d) was therapeutically effective (0.15-0.23 g/dl Hb-increase/d). When given 100 or 300 mg Fe/d Fe-PM together with meal, 3 out of 6 patients showed a higher iron utilization rate (3.4-11.9%/d) than given without meal (0.5-7.5%/d). In vitro incubation studies demonstrated that Fe-PM is very stable at neutral pH. A small release of iron from the high molecular weight complex was found only at low pH (< 2). However, high amounts of ionic iron were measured in the reaction tubes after incubating solutions of Fe-PM together with ascorbic acid. This finding could explain the somewhat higher bioavailability of Fe-PM when given with vitamin C containing meals.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8053973

  20. Direct method for continuous determination of iron oxidation by autotrophic bacteria.

    PubMed

    Steiner, M; Lazaroff, N

    1974-11-01

    A method for direct, continuous determination of ferric ions produced in autotrophic iron oxidation, which depends upon the measurement of ferric ion absorbance at 304 nm, is described. The use of initial rates is shown to compensate for such changes in extinction during oxidation, which are due to dependence of the extinction coefficient on the ratio of complexing anions to ferric ions. A graphical method and a computer method are given for determination of absolute ferric ion concentration, at any time interval, in reaction mixtures containing Thiobacillus ferrooxidans and ferrous ions at known levels of SO(4) (2+) and hydrogen ion concentrations. Some examples are discussed of the applicability of these methods to study of the rates of ferrous ion oxidation related to sulfate concentration. PMID:4441066

  1. Direct Method for Continuous Determination of Iron Oxidation by Autotrophic Bacteria

    PubMed Central

    Steiner, Michael; Lazaroff, Norman

    1974-01-01

    A method for direct, continuous determination of ferric ions produced in autotrophic iron oxidation, which depends upon the measurement of ferric ion absorbance at 304 nm, is described. The use of initial rates is shown to compensate for such changes in extinction during oxidation, which are due to dependence of the extinction coefficient on the ratio of complexing anions to ferric ions. A graphical method and a computer method are given for determination of absolute ferric ion concentration, at any time interval, in reaction mixtures containing Thiobacillus ferrooxidans and ferrous ions at known levels of SO42+ and hydrogen ion concentrations. Some examples are discussed of the applicability of these methods to study of the rates of ferrous ion oxidation related to sulfate concentration. PMID:4441066

  2. The selectivity of Vibrio cholerae H-NOX for gaseous ligands follows the "sliding scale rule" hypothesis. Ligand interactions with both ferrous and ferric Vc H-NOX.

    PubMed

    Wu, Gang; Liu, Wen; Berka, Vladimir; Tsai, Ah-lim

    2013-12-31

    Vc H-NOX (or VCA0720) is an H-NOX (heme-nitric oxide and oxygen binding) protein from facultative aerobic bacterium Vibrio cholerae. It shares significant sequence homology with soluble guanylyl cyclase (sGC), a NO sensor protein commonly found in animals. Similar to sGC, Vc H-NOX binds strongly to NO and CO with affinities of 0.27 nM and 0.77 ?M, respectively, but weakly to O2. When positioned on a "sliding scale" plot [Tsai, A.-l., et al. (2012) Biochemistry 51, 172-186], the line connecting log K(D)(NO) and log K(D)(CO) of Vc H-NOX can almost be superimposed with that of Ns H-NOX. Therefore, the measured affinities and kinetic parameters of gaseous ligands to Vc H-NOX provide more evidence to validate the "sliding scale rule" hypothesis. Like sGC, Vc H-NOX binds NO in multiple steps, forming first a six-coordinate heme-NO complex at a rate of 1.1 × 10(9) M(-1) s(-1), and then converts to a five-coordinate heme-NO complex at a rate that is also dependent on NO concentration. Although the formation of oxyferrous Vc H-NOX cannot be detected at a normal atmospheric oxygen level, ferrous Vc H-NOX is oxidized to the ferric form at a rate of 0.06 s(-1) when mixed with O2. Ferric Vc H-NOX exists as a mixture of high- and low-spin states and is influenced by binding to different ligands. Characterization of both ferric and ferrous Vc H-NOX and their complexes with various ligands lays the foundation for understanding the possible dual roles in gas and redox sensing of Vc H-NOX. PMID:24351060

  3. The Oxidation of Iron in a Gel Using Consumer Chemicals

    NASA Astrophysics Data System (ADS)

    Wright, Stephen W.; Folger, Marsha R.; Quinn, Ryan P.

    2005-11-01

    The classic demonstration of the corrosion or oxidation of a steel nail in an agar gel may be conducted using inexpensive chemicals that are commonly available to the consumer on the retail market. The ferric ion produced is detected with salicylate to give a garnet-red color at the anodic areas where oxidation of iron occurs.

  4. Ferric ion mediated photodecomposition of aqueous perfluorooctane sulfonate (PFOS) under UV irradiation and its mechanism.

    PubMed

    Jin, Ling; Zhang, Pengyi; Shao, Tian; Zhao, Shiliang

    2014-04-30

    Perfluorooctane sulfonate (PFOS) recently has received much attention due to its global distribution, environmental persistence and bioaccumulation. The methods for PFOS decomposition are very limited due to its inertness. In this report we first found the photodecomposition of PFOS under UV was greatly accelerated by addition of ferric ions. In the presence of ferric ion (100 ?M), PFOS (20 ?M) decreased to below the detection limit within 48 h, with the rate constant of 1.67 d(-1), which was 50 times higher than that by direct photolysis (0.033 d(-1)). Besides fluoride and sulfate ions, C2-C8 perfluorocarboxylic acids (PFCAs) were identified as the main intermediates. It was found that addition of PFOS into the FeCl3 aqueous solution led to reduction of UV absorption, and the presence of ferric ion reduced the response of PFOS as analyzed by UPLC-MS/MS, which indicated that PFOS formed a complex with ferric ion. The ESR detection indicated that the electronic state of Fe(3+)-PFOS complex changed during reaction. And the role of oxygen and hydroxyl radical on the defluorination of PFOS was investigated. Accordingly the mechanism for PFOS photodecomposition in the presence of ferric ion was proposed. PMID:24583810

  5. A Cytochrome b561 with Ferric Reductase Activity from the Parasitic Blood Fluke, Schistosoma japonicum

    PubMed Central

    Glanfield, Amber; McManus, Donald P.; Smyth, Danielle J.; Lovas, Erica M.; Loukas, Alex; Gobert, Geoffrey N.; Jones, Malcolm K.

    2010-01-01

    Background Iron has an integral role in numerous cellular reactions and is required by virtually all organisms. In physiological conditions, iron is abundant in a largely insoluble ferric state. Ferric reductases are an essential component of iron uptake by cells, reducing iron to the soluble ferrous form. Cytochromes b561 (cyts-b561) are a family of ascorbate reducing transmembrane proteins found in most eukaryotic cells. The identification of the ferric reductase duodenal cytochrome b (dcytb) and recent observations that other cyts-b561 may be involved in iron metabolism have opened novel perspectives for elucidating their physiological function. Methodology/Principal Findings Here we have identified a new member of the cytochrome b561 (Sjcytb561) family in the pathogenic blood fluke Schistosoma japonicum that localises to the outer surface of this parasitic trematode. Heterologous expression of recombinant Sjcyt-b561 in a Saccharomyces cerevisiae mutant strain that lacks plasma membrane ferrireductase activity demonstrated that the molecule could rescue ferric reductase activity in the yeast. Significance/Conclusions This finding of a new member of the cytochrome b561 family further supports the notion that a ferric reductase function is likely for other members of this protein family. Additionally, the localisation of Sjcytb561 in the surface epithelium of these blood-dwelling schistosomes contributes further to our knowledge concerning nutrient acquisition in these parasites and may provide novel targets for therapeutic intervention. PMID:21103361

  6. Evaluation of Ferric and Ferrous Iron Therapies in Women with Iron Deficiency Anaemia

    PubMed Central

    Berber, Ilhami; Erkurt, Mehmet Ali; Aydogdu, Ismet; Kuku, Irfan

    2014-01-01

    Introduction. Different ferric and ferrous iron preparations can be used as oral iron supplements. Our aim was to compare the effects of oral ferric and ferrous iron therapies in women with iron deficiency anaemia. Methods. The present study included 104 women diagnosed with iron deficiency anaemia after evaluation. In the evaluations performed to detect the aetiology underlying the iron deficiency anaemia, it was found and treated. After the detection of the iron deficiency anaemia aetiology and treatment of the underlying aetiology, the ferric group consisted of 30 patients treated with oral ferric protein succinylate tablets (2 × 40?mg elemental iron/day), and the second group consisted of 34 patients treated with oral ferrous glycine sulphate tablets (2 × 40?mg elemental iron/day) for three months. In all patients, the following laboratory evaluations were performed before beginning treatment and after treatment. Results. The mean haemoglobin and haematocrit increases were 0.95?g/dL and 2.62% in the ferric group, while they were 2.25?g/dL and 5.91% in the ferrous group, respectively. A significant difference was found between the groups regarding the increase in haemoglobin and haematocrit values (P < 0.05). Conclusion. Data are submitted on the good tolerability, higher efficacy, and lower cost of the ferrous preparation used in our study. PMID:25006339

  7. Nitrosative Stress and Apoptosis by Intravenous Ferumoxytol, Iron Isomaltoside 1000, Iron Dextran, Iron Sucrose, and Ferric Carboxymaltose in a Nonclinical Model.

    PubMed

    Toblli, J E; Cao, G; Giani, J F; Dominici, F P; Angerosa, M

    2014-07-22

    Iron is involved in the formation as well as in the scavenging of reactive oxygen and nitrogen species. Thus, iron can induce as well as inhibit both oxidative and nitrosative stress. It also has a key role in reactive oxygen and nitrogen species-mediated apoptosis. We assessed the differences in tyrosine nitration and caspase 3 expression in the liver, heart, and kidneys of rats treated weekly with intravenous ferumoxytol, iron isomaltoside 1000, iron dextran, iron sucrose and ferric carboxymaltose (40?mg iron/kg body weight) for 5 weeks. Nitrotyrosine was quantified in tissue homogenates by Western blotting and the distribution of nitrotyrosine and caspase 3 was assessed in tissue sections by immunohistochemistry. Ferric carboxymaltose and iron sucrose administration did not result in detectable levels of nitrotyrosine or significant levels of caspase 3?vs. control in any of the tissue studied. Nitrotyrosine and caspase 3 levels were significantly (p<0.01) increased in all assessed organs of animals treated with iron dextran and iron isomaltoside 1000, as well as in the liver and kidneys of ferumoxytol-treated animals compared to isotonic saline solution (control). Nitrotyrosine and caspase 3 levels were shown to correlate positively with the amount of Prussian blue-detectable iron(III) deposits in iron dextran- and iron isomaltoside 1000-treated rats but not in ferumoxytol-treated rats, suggesting that iron dextran, iron isomaltoside 1000 and ferumoxytol induce nitrosative (and oxidative) stress as well as apoptosis via different mechanism(s). PMID:25050519

  8. An Interpretation of the Magnetic Properties of some Iron-Oxide Powders: II

    Microsoft Academic Search

    W P Osmond

    1953-01-01

    An earlier study of the magnetic properties of fine dispersed powders of acicular grains of magnetite and of ?-ferric oxide, derived by reduction and re-oxidation of dehydrated pigment oxides, has been revised, taking account of the probable cavities in the powder particles caused by the loss of oxygen during the chemical and structural transformations. Excellent quantitative agreement is now found

  9. The oxidizing power of illinois coal. I. The reaction with titanous chloride

    USGS Publications Warehouse

    Yoke, G.R.; Harman, C.A.

    1941-01-01

    Illinois coals which have been exposed to air or oxygen show a small but definite ability to oxidize titanous chloride. This oxidizing power is gained very rapidly when freshly ground coal is exposed to air. Neither the magnitude nor the rapid increase of this oxidizing power can be accounted for entirely by the presence or the formation of soluble ferric compounds in the coal.

  10. Mineralogy at Gusev Crater from the Mossbauer spectrometer on the Spirit Rover

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Klingelhofer, G.; Bernhardt, B.; Schroder, C.; Rodionov, D. S.; De Souza, P. A. Jr; Yen, A.; Gellert, R.; Evlanov, E. N.; Foh, J.; Kankeleit, E.; Gutlich, P.; Ming, D. W.; Renz, F.; Wdowiak, T.; Squyres, S. W.; Arvidson, R. E.

    2004-01-01

    Mossbauer spectra measured on Mars by the Spirit rover during the primary mission are characterized by two ferrous iron doublets (olivine and probably pyroxene) and a ferric iron doublet (tentatively associated to nanophase ferric iron oxide). Two sextets resulting from nonstoichiometric magnetite are also present, except for a coating on the rock Mazatzal, where a hematite-like sextet is present. Greater proportions of ferric-bearing phases are associated with undisturbed soils and rock surfaces as compared to fresh rock surfaces exposed by grinding. The ubiquitous presence of olivine in soil suggests that physical rather than chemical weathering processes currently dominate at Gusev crater.

  11. Mineralogy at Gusev Crater from the Mössbauer spectrometer on the Spirit Rover.

    PubMed

    Morris, R V; Klingelhöfer, G; Bernhardt, B; Schröder, C; Rodionov, D S; De Souza, P A; Yen, A; Gellert, R; Evlanov, E N; Foh, J; Kankeleit, E; Gütlich, P; Ming, D W; Renz, F; Wdowiak, T; Squyres, S W; Arvidson, R E

    2004-08-01

    Mössbauer spectra measured on Mars by the Spirit rover during the primary mission are characterized by two ferrous iron doublets (olivine and probably pyroxene) and a ferric iron doublet (tentatively associated to nanophase ferric iron oxide). Two sextets resulting from nonstoichiometric magnetite are also present, except for a coating on the rock Mazatzal, where a hematite-like sextet is present. Greater proportions of ferric-bearing phases are associated with undisturbed soils and rock surfaces as compared to fresh rock surfaces exposed by grinding. The ubiquitous presence of olivine in soil suggests that physical rather than chemical weathering processes currently dominate at Gusev crater. PMID:15297666

  12. Involvement of lipid peroxidation, oncogene expression and induction of apoptosis in the antitumorous activity of ferric-sorbitol-citrate.

    PubMed

    Poljak-Blazi, M; Kralj, M; Hadzija, M P; Zarkovi?, N; Zarkovi?, K; Waeg, G

    2000-06-01

    We described before that iron-containing, anti-anaemic drug, ferric-sorbitol-citrate complex (FSC) inhibited proliferation of various murine cancer cells in vitro and caused tumour regression in vivo, but did not affect proliferation of the non-malignant cells. The aim of this study was to evaluate further the anticancer activity mechanism of FSC using human colon cancer cell line CaCo2. After treatment with FSC for 72 hours impaired proliferative ability and viability of CaCo2 cells as observed. Growth modification caused by FSC involved diminished expression of Bcl-2, and over-expression of mp53 proto-oncogenes, accompanied by increased incidence of apoptosis. Immunostaining the cells applying monoclonal antibodies for lipid peroxidation product 4-hydroxynonenal (HNE) showed that FSC-iron increased intracellular HNE, but did not induce severe HNE-mediated oxidative stress. Thus, antitumorous mechanism of FSC involves modulation of oncogene expression and induction of apoptosis apparently not triggered by lipid peroxidation-mediated oxidative stress, although FSC might restore endogenous HNE production in the CaCo2 cells to level resembling physiological for various non-malignant cells and tissues. Higher dose of FSC increased also number of intracellular ferritin positive CaCo2 cells. PMID:10941536

  13. Thermoresponse improvement of poly(N-isopropylacrylamide) hydrogels via formation of poly(sodium p-styrenesulfonate) nanophases.

    PubMed

    Li, Jingang; Cong, Houluo; Li, Lei; Zheng, Sixun

    2014-08-27

    The block copolymer networks composed of poly(N-isopropylacrylamide) (PNIPAM) and poly(sodium p-styrenesulfonate) were synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization with ?,?-didithiobenzoate-terminated poly(sodium p-styrenesulfonate) (PSSNa) as the macromolecular chain transfer agent. It was found that the block copolymer networks were microphase-separated as evidenced by means of transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). In the block copolymer networks, spherical or cylindrical PSSNa microdomains were finely dispersed into continuous PNIPAM matrixes. In comparison with unmodified PNIPAM hydrogel, the nanostructured hydrogels displayed improved thermoresponsive properties. In addition, the swelling ratios of the PSSNa-modified PNIPAM hydrogels were significantly higher than that of plain PNIPAM hydrogel. The improvement of thermoresponse was attributable to the formation of the PSSNa nanophases, which promoted the transportation of water molecules in the cross-linked networks. PMID:25036696

  14. Effects of melt composition on Fe3+/Fe2+ in silicate melts: a step to model ferric/ferrous ratio in multicomponent systems

    NASA Astrophysics Data System (ADS)

    Borisov, Alexander; Behrens, Harald; Holtz, Francois

    2015-02-01

    The effect of Al2O3, MgO and total iron on the ferric/ferrous ratio in silicate melts was investigated in model silicate melts in the temperature range 1400-1550 °C at 1 atm total pressure. The experiments were done mostly in air and partially in pure CO2. It is demonstrated that an increase in Al2O3 concentration in a basaltic melt results in a moderate decrease of Fe3+/Fe2+ ratio. In contrast, the increase in Al2O3 in more silicic melts results in a much more pronounced decrease of Fe3+/Fe2+ ratio. The increase of MgO concentration in a basaltic melt results in a moderate increase of Fe3+/Fe2+ ratio but has a negligible effects in more silicic melts. The different behavior of Al2O3 and MgO in basaltic and more silicic melts indicates that at constant T- fO2 conditions, the effects of melt composition on ferric/ferrous ratio cannot be predicted accurately as a function of ? d i X i where d i are fixed empirical coefficients and X i are mole fractions of the main oxide component in silicate melts. We suggest an alternative approach which accounts for the interaction of cations in complex silicate melts. Based on the data obtained in this study, an equation predicting the ferric/ferrous ratio of ultramafic to silicic melts at air conditions with changing SiO2, TiO2, Al2O3, total iron, MgO and P2O5 is proposed.

  15. The Role of the Distal and Proximal Protein Environments in Controlling the Ferric Spin State and in Stabilizing Thiolate Ligation

    E-print Network

    Boxer, Steven G.

    thiolate-ligated ferric cytochrome P450 have been prepared using H93G myoglobin containing thiolate ligands and in stabilizing thiolate ligation in heme systems, respectively. Introduction Cytochrome P450 enzymes utilize spectroscopically resemble five-coordinate high- spin substrate-bound ferric P450, which contains a thiolate

  16. Metabolic characterization of lactic acid bacterium Lactococcus garvieae sk11, capable of reducing ferric iron, nitrate, and fumarate.

    PubMed

    Yun, Su Hee; Hwang, Tae Sik; Park, Doo Hyun

    2007-02-01

    A lactic acid bacterium capable of anaerobic respiration was isolated from soil with ferric iron-containing glucose basal medium and identified as L. garvieae by using 16S rDNA sequence homology. The isolate reduced ferric iron, nitrate, and fumarate to ferrous iron, nitrite, and succinate, respectively, under anaerobic N2 atmosphere. Growth of the isolate was increased about 30-39% in glucose basal medium containing nitrate and fumarate, but not in the medium containing ferric iron. Specifically, metabolic reduction of nitrate and fumarate is thought to be controlled by the specific genes fnr, encoding FNR-like protein, and nir, regulating fumarate-nitrate reductase. Reduction activity of ferric iron by the isolate was estimated physiologically, enzymologically, and electrochemically. The results obtained led us to propose that the isolate metabolized nitrate and fumarate as an electron acceptor and has specific enzymes capable of reducing ferric iron in coupling with anaerobic respiration. PMID:18051752

  17. Low Temperature Photo-Oxidation of Chloroperoxidase Compound II

    PubMed Central

    Yuan, Xinting; Sheng, Xin; Horner, John H.; Bennett, Brian; Fung, Leslie W.-M.; Newcomb, Martin

    2010-01-01

    Oxidation of the heme-thiolate enzyme chloroperoxidase (CPO) from Caldariomyces fumago with peroxynitrite (PN) gave the Compound II intermediate, which was photo-oxidized with 365 nm light to give a reactive oxidizing species. Cryo-solvents at pH ? 6 were employed, and reactions were conducted at temperatures as low as ?50 °C. The activity of CPO as evaluated by the chlorodimedone assay was unaltered by treatment with PN or by production of the oxidizing transient and subsequent reaction with styrene. EPR spectra at 77 K gave the amount of ferric protein at each stage in the reaction sequence. The PN oxidation step gave a 6:1 mixture of Compound II and ferric CPO, the photolysis step gave an approximate 1:1 mixture of active oxidant and ferric CPO, and the final mixture after reaction with excess styrene contained ferric CPO in 80% yield. In single turnover reactions at ?50 °C, styrene was oxidized to styrene oxide in high yield. Kinetic studies of styrene oxidation at ?50 °C displayed saturation kinetics with an equilibrium constant for formation of the complex of Kbind = 3.8 × 104 M?1 and an oxidation rate constant of kox = 0.30 s?1. UV-visible spectra of mixtures formed in the photo-oxidation sequence at ca. ?50 °C did not contain the signature Q-band absorbance at 690 nm ascribed to CPO Compound I prepared by chemical oxidation of the enzyme, indicating that different species were formed in the chemical oxidation and the photo-oxidation sequence. PMID:20674981

  18. Resonance Raman Study of Ferric Heme Adducts of Dehaloperoxidase from Amphitrite ornata †

    Microsoft Academic Search

    Jennifer Belyea; Curtis M. Belyea; Simon Lappi; Stefan Franzen

    2006-01-01

    The study of axial ligation by anionic ligands to ferric heme iron by resonance Raman spectroscopy provides a basis for comparison of the intrinsic electron donor ability of the proximal histidine in horse heart myoglobin (HHMb), dehaloperoxidase (DHP), and horseradish peroxidase (HRP). DHP is a dimeric hemoglobin (Hb) originally isolated from the terebellid polychaete Amphitrite ornata. The monomers are structurally

  19. MECHANISM OF CATALYTIC ACTION OF CUPRIC IONS IN FERRIC SALTS LEACHING OF MILLERITE

    Microsoft Academic Search

    Maria CHOJNACKA; Dorota WAWRZAK

    2001-01-01

    Based on experimental leaching results of millerite as well as changes in the composition and microstructure of solid residue surface after leaching with ferric salts acid solutions the mechanism of catalytic action of cupric ions has been proposed. The solid residues were examined using a scanning microscope (SEM), X-ray diffraction, electron microprobe and chemical analyses. It was found that cupric

  20. Treatment of rheumatoid synovitis of the knee with intraarticular injection of dysprosium 165-ferric hydroxide macroaggregates

    Microsoft Academic Search

    Clement B. Sledge; Joseph D. Zuckerman; Michael R. Zalutsky; Robert W. Atcher; Sonya Shortkroff; David R. Lionberger; Howard A. Rose; Brian J. Hurson; Peter A. Lankenner; Ronald J. Anderson; William A. Bloomer

    1986-01-01

    One hundred eight knees of 93 patients with seropositive rheumatoid arthritis and persistent synovitis of the knee were treated with an intraarticular injection of 270 mCi of dysprosium 165 bound to ferric hydroxide macroaggregate. Leakage of radioactivity from the injected joint was minimal. Mean leakage to the venous blood 3 hours after injection was 0.11% of the injected dose; this

  1. ANALYSIS OF FERRIC AND FERROUS IONS IN SOIL EXTRACTS BY ION CHROMATOGRAPHY

    EPA Science Inventory

    A method using ion chromatography (IC) for the analysis of ferrous (Fe 2+) and ferric (Fe 3+) ions in soil extracts has been developed. This method uses an ion exchange column with detection at 520 nm after post-column derivatization. Selectivity is achieved by using an anionic...

  2. A novel electrochemical process for the recovery and recycling of ferric chloride from precipitation sludge.

    PubMed

    Mejia Likosova, E; Keller, J; Poussade, Y; Freguia, S

    2014-03-15

    During wastewater treatment and drinking water production, significant amounts of ferric sludge (comprising ferric oxy-hydroxides and FePO4) are generated that require disposal. This practice has a major impact on the overall treatment cost as a result of both chemical addition and the disposal of the generated chemical sludge. Iron sulfide (FeS) precipitation via sulfide addition to ferric phosphate (FePO4) sludge has been proven as an effective process for phosphate recovery. In turn, iron and sulfide could potentially be recovered from the FeS sludge, and recycled back to the process. In this work, a novel process was investigated at lab scale for the recovery of soluble iron and sulfide from FeS sludge. Soluble iron is regenerated electrochemically at a graphite anode, while sulfide is recovered at the cathode of the same electrochemical cell. Up to 60 ± 18% soluble Fe and 46 ± 11% sulfide were recovered on graphite granules for up-stream reuse. Peak current densities of 9.5 ± 4.2 A m(-2) and minimum power requirements of 2.4 ± 0.5 kWh kg Fe(-1) were reached with real full strength FeS suspensions. Multiple consecutive runs of the electrochemical process were performed, leading to the successful demonstration of an integrated process, comprising FeS formation/separation and ferric/sulfide electrochemical regeneration. PMID:24397913

  3. Identification and Characterization of a Novel Extracellular Ferric Reductase from Mycobacterium paratuberculosis

    Microsoft Academic Search

    MATTHIAS HOMUTH; PETER VALENTIN-WEIGAND; M. ROHDE

    1998-01-01

    A novel extracellular mycobacterial enzyme was identified in the ruminant pathogen Mycobacterium para- tuberculosis. The enzyme was capable of mobilizing iron from different sources such as ferric ammonium citrate, ferritin, and transferrin by reduction of the metal. The purified reductase had a calculated Mr of 17,000, was sensitive to proteinase K treatment, and had an isoelectric point of pH 9.

  4. PIN OAK AND SILVER MAPLE CHLOROSIS TREATMENT WITH FERRIC AMMONIUM CITRATE SOLUTION1

    Microsoft Academic Search

    Philip A. Pierce; David P. Mooter

    Trunk injections of a commercially available ferric ammonium citrate solution were found to be effective in cor- recting chlorosis of pin oak and silver maple. Two previously evaluated treatments for chlorosis of pin oak were tested again for comparison. Trunk injections of manganese sulfate, a fungicide, and an N-P-K fertilizer were also tested on silver maple, but did not improve

  5. Perturbation-Response Scanning Reveals Ligand Entry-Exit Mechanisms of Ferric Binding Protein

    E-print Network

    Yanikoglu, Berrin

    Perturbation-Response Scanning Reveals Ligand Entry-Exit Mechanisms of Ferric Binding Protein Canan in the presence of the ligand is proposed. We introduce a new tool that we term perturbation-response scanning of computational perturbation/response techniques based on linear response theory, by sequentially applying

  6. Ferric Leghemoglobin in Plant-Attached Legu mi nous N odu les

    Microsoft Academic Search

    Keuk-ki Lee; Linda L. Shearman; Kipp Erickson; Robert V. Klucas

    Leghemoglobin (Lb) is essential for nitrogen fixation by intact leguminous nodules. To determine whether ferric Lb (Lb3+) was detectable in nodules under normal or stressed conditions, we monitored the status of Lb in intact nodules attached to sweet clover (Meldotos officinalis) and soybean (Glycine max (L.) Merr.) roots exposed to various conditions. The effects of N, and O, streams and

  7. TRANSFORMATION AND MOBILIZATION OF ARSENIC ADSORBED ON GRANULAR FERRIC HYDROXIDE UNDER BIO-REDUCTIVE CONDITIONS

    EPA Science Inventory

    Biotic and abiotic reduction of arsenic (V) and iron (III) influences the partioning of arsenic (As) between the solid and aqueous phases in soils, sediments and wastes. In this study, laboratory experiments on arsenic adsorbed on granular ferric hydroxide (GFH) was performed to ...

  8. Enterobactin Protonation and Iron Release: Structural Characterization of the Salicylate Coordination Shift in Ferric Enterobactin

    PubMed Central

    Abergel, Rebecca J.; Warner, Jeffrey A.; Shuh, David K.; Raymond, Kenneth N.

    2011-01-01

    The siderophore enterobactin (Ent) is produced by many species of enteric bacteria to mediate iron uptake. This iron scavenger can be reincorporated by the bacteria as the ferric complex [FeIII(Ent)]3- and is subsequently hydrolyzed by an esterase to facilitate intracellular iron release. Recent literature reports on altered protein recognition and binding of modified enterobactin increase the significance of understanding the structural features and solution chemistry of ferric enterobactin. The structure of the neutral protonated ferric enterobactin complex [FeIII(H3Ent)]0 has been the source of some controversy and confusion in the literature. To demonstrate the proposed change of coordination from the tris-catecholate [FeIII(Ent)]3- to the tris-salicylate [FeIII(H3Ent)]0 upon protonation, the coordination chemistry of two new model compounds N,N’,N”-tris[2-(hydroxybenzoyl)carbonyl]cyclotriseryl trilactone (SERSAM) and N,N’,N”-tris[2-hydroxy,3-methoxy(benzoyl)carbonyl]cyclotriseryl trilactone (SER(3M)SAM) was examined in solution and solid state. Both SERSAM and SER(3M)SAM form tris-salicylate ferric complexes with spectroscopic and solution thermodynamic properties (with log ?110 values of 39 and 38 respectively) similar to those of [FeIII(H3Ent)]0. The fits of EXAFS spectra of the model ferric complexes and the two forms of ferric enterobactin provided bond distances and disorder factors in the metal coordination sphere for both coordination modes. The protonated [FeIII(H3Ent)]0 complex (dFe-O = 1.98 Å, ?2stat(O) = 0.00351(10) Å2) exhibits a shorter average Fe-O bond length but a much higher static Debye-Waller factor for the first oxygen-shell than the catecholate [FeIII(Ent)]3- complex (dFe-O = 2.00 Å, ?2stat(O) = 0.00067(14) Å2). 1H NMR spectroscopy was used to monitor the amide bond rotation between the catecholate and salicylate geometries using the gallic complexes of enterobactin; [GaIII(Ent)]3- and [GaIII(H3Ent)]0. The ferric salicylate complexes display quasi-reversible reduction potentials from ?89 mV to ?551 mV (relative to the normal hydrogen electrode NHE) which supports the feasibility of a low pH iron release mechanism facilitated by biological reductants. PMID:16819888

  9. Reduction of costs for anemia-management drugs associated with the use of ferric citrate

    PubMed Central

    Thomas, Anila; Peterson, Leif E

    2014-01-01

    Background Ferric citrate is a novel phosphate binder which has the potential to reduce usage of erythropoietin-stimulating agents (ESAs) and intravenous (IV) iron used for anemia management during hemodialysis (HD) among patients with end-stage renal disease (ESRD). Currently, the potential health care cost savings on a national scale due to the use of ferric citrate in ESRD are undetermined. Methods Per-patient-per-year costs of ESAs (Epogen® and Aranesp® [Amgen Inc., CA, USA]) and IV iron (Venofer® [American Regent, Inc., NY, USA] and Ferrlecit® [Sanofi US, Bridgewater, NJ, USA]) were based on RED BOOK™ (Truven Health Analytics New York, NY, USA) costs combined with the Centers for Medicare and Medicaid Services (CMS) base rate and actual usage in 2011 for the four drugs. The annual number of outpatients undergoing HD in the US was based on frequencies reported by the USRDS (United States Renal Data System). Monte Carlo uncertainty analysis was performed to determine total annual costs and cost reduction based on ferric citrate usage. Results Total annual cost of ESAs and IV iron for anemia management in ESRD determined by Monte Carlo analysis assuming CMS base rate value was 5.127 (3.664–6.260) billion USD. For actual utilization in 2011, total annual cost of ESAs and IV iron was 3.981 (2.780–4.930) billion USD. If ferric citrate usage reduced ESA utilization by 20% and IV iron by 40%, then total cost would be reduced by 21.2% to 4.038 (2.868–4.914) billion USD for the CMS base rate, and by 21.8% to 3.111 (2.148–3.845) billion USD, based on 2011 actual utilization. Conclusion It is likely that US health care costs for anemia-management drugs associated with ESRD among HD patients can be reduced by using ferric citrate as a phosphate binder. PMID:24899820

  10. Use of ferric thiocyanate derivatization for quantification of polysorbate 80 in high concentration protein formulations.

    PubMed

    Savjani, Nimesh; Babcock, Eugene; Khor, Hui Koon; Raghani, Anil

    2014-12-01

    Quantitation of polysorbate 80 in high protein formulation using solid-phase extraction (SPE) followed by derivatization with cobalt thiocyanate and UV measurement of the complex at 620 nm resulted in lower recovery of polysorbate 80. Dilution of protein samples with water improved the recovery of polysorbate, however, it compromised the sensitivity of the method when cobalt thiocyanate was used for derivatization. The presented work discusses an evaluation of alternative approaches for increasing the sensitivity of the quantitation method for polysorbate using ferric thiocyanate and molybdenum thiocyanate. Ferric thiocyanate complex of polysorbate 80 exhibited the highest sensitivity among the metals thiocyanate evaluated in the current work. The improvement in the sensitivity through derivatization with ferric thiocyanate allowed 10-fold dilution of a 140 mg mL(-1) protein sample without affecting the recovery or compromising the sensitivity of polysorbate 80 quantitation, indicating that this methodology could be used as an alternate approach for the quantitation of polysorbate 80 in high concentration protein formulations. Stability of ferric thiocynate and cobalt thiocyanate complex was also studied. When these complexes were allowed to equilibrate for 1h between an organic layer containing polysorbate/thiocynate complex and an aqueous layer containing un-reacted metal thiocyanate, it resulted in the most reproducible UV absorbance measurements. The SPE method for quantification of polysorbate 80 using ferric thiocyanate for derivatization provided accuracy (% spike recovery) within 107%, reproducibility (%relative standard deviation) less than 11.7%. The method is linear from 0.0001 to 0.008% polysorbate 80 concentrations in the formulations with protein formulations as high as 140 mg mL(-1). PMID:25159444

  11. Goethite on Mars: A Laboratory Study of Physically and Chemically Bound Water in Ferric Oxides

    Microsoft Academic Search

    James B. Pollack; Douglas Pitman; Bishun N. Khare; Carl Sagan

    1970-01-01

    A thermogravimetric analysis of the decomposition of goethite-rich samples of limonite and measurement of the equilibrium vapor pressure of the water physically bound in the sample are performed. The heats of sorption for the physically bound component are determined; an activation energy of 29 4- 3 kcal\\/mole for goethite decomposition to hematite is found between 225 and 390øC. The goethite-hematite

  12. Mössbauer mineralogy of rock, soil, and dust at Gusev crater, Mars: Spirit's journey through weakly altered olivine basalt on the plains and pervasively altered basalt in the Columbia Hills

    Microsoft Academic Search

    R. V. Morris; G. Klingelhöfer; C. Schröder; D. S. Rodionov; A. Yen; D. W. Ming; P. A. de Souza; I. Fleischer; T. Wdowiak; R. Gellert; B. Bernhardt; E. N. Evlanov; B. Zubkov; J. Foh; U. Bonnes; E. Kankeleit; P. Gütlich; F. Renz; S. W. Squyres; R. E. Arvidson

    2006-01-01

    The Mössbauer spectrometer on Spirit measured the oxidation state of Fe, identified Fe-bearing phases, and measured relative abundances of Fe among those phases for surface materials on the plains and in the Columbia Hills of Gusev crater. Eight Fe-bearing phases were identified: olivine, pyroxene, ilmenite, magnetite, nanophase ferric oxide (npOx), hematite, goethite, and a Fe3+-sulfate. Adirondack basaltic rocks on the

  13. Primary Ferric Iron-Bearing Rhönite in Plutonic Igneous Angrite NWA 4590: Implications for Redox Conditions on the Angrite Parent Body

    NASA Astrophysics Data System (ADS)

    Kuehner, S. M.; Irving, A. J.

    2007-12-01

    Northwest Africa 4590 is a heterogeneous olivine gabbro with cumulate texture composed of Al-Ti-rich clinopyroxene, pure anorthite, Ca-rich olivine, kirschsteinite and ulvöspinel, with accessory troilite, merrillite, Ca silicophosphate, kamacite and glasses [1]. Rhönite now has been identified in this specimen (for the first time in any angrite) as (1) a large (0.65 mm long), blocky, anhedral grain adjacent to anorthite, kirschsteinite and troilite, (2) ca. 15 micron grains along grain boundaries of the major phases (in one case in contact with clinopyroxene and metal), and (3) ca. 30 micron grains within melt inclusions and veins composed of kirschsteinite, olivine, anorthite, troilite, hercynite and glass. The rhönite is nearly opaque in transmitted light, with a deep cinnamon-red color on thin grain edges. The average composition of the largest grain is (in wt.%): SiO2 23.6, TiO2 9.9, Al2O3 16.3, Cr2O3 0.1, FeOt 33.6, MnO 0.14, MgO 3.5, CaO 13.1. Stoichiometry (14 cations, 20 oxygen atoms) requires about 12% of the total iron to be in the ferric state, resulting in the nominal formula: (Ca2.01Mn0.02)(Fe2+3.55Fe3+0.45Mg0.75Al0.12Cr0.15)Ti0.9 5(Si3.37Al2.63)O20 In the co-existing ulvöspinel about 18% of the iron must be ferric to achieve charge balance; likewise, Fe-Ti spinel coexisting with metal in Angra dos Reis contains ferric iron [2]. In contrast, the spinel (Cr-pleonaste) in metal-rich angrite NWA 2999 is stoichiometric without any apparent ferric iron. The coexistence of ferric iron- bearing silicate and oxide phases with Fe metal implies that the oxygen fugacity during crystallization of NWA 4590 was somewhat more oxidizing than that of the IW buffer. Compositions of primary (pre-exsolution) olivine and kirschsteinite in NWA 4590 record a minimum magmatic temperature of 910-950°C, based on the solvus of [3]. Previous experimental studies [4] also imply that other metal-bearing plutonic (AdoR, LEW 86010) and quench-textured (LEW 87051) angrites equilibrated at oxygen fugacities near QFM - 2 log units and relatively high temperatures. Although not previously known from angrites, rhönite has been reported from terrestrial alkalic rocks, CV chondrites and a lunar mare basalt [5]. [1] Irving A. et al. (2006) EOS, Trans. AGU 87, #P51E-1245; Kuehner S. and Irving A. (2007) LPS XXXVIII, #1344 [2] Prinz M. et al. (1977) EPSL 35, 317-330 [3] Mukhopadhyay D. and Lindsley D. (1983) Amer. Mineral. 68, 1089-1094 [4] Jurewicz A. et al. (1991) Science 252, 695-698; McKay G. et al. (1994) GCA 58, 2911-2919 [5] Treiman A. (2007) LPS XXXVIII, #1244.

  14. Super adsorption capability from amorphousization of metal oxide nanoparticles for dye removal

    PubMed Central

    Li, L. H.; Xiao, J.; Liu, P.; Yang, G. W.

    2015-01-01

    Transitional metal oxide nanoparticles as advanced environment and energy materials require very well absorption performance to apply in practice. Although most metal oxides are based on crystalline, high activities can also be achieved with amorphous phases. Here, we reported the adsorption behavior and mechanism of methyl blue (MB) on the amorphous transitional metal oxide (Fe, Co and Ni oxides) nanoparticles, and we demonstrated that the amorphousization of transitional metal oxide (Fe, Co and Ni oxides) nanoparticles driven by a novel process involving laser irradiation in liquid can create a super adsorption capability for MB, and the maximum adsorption capacity of the fabricated NiO amorphous nanostructure reaches up to 10584.6?mgg?1, the largest value reported to date for all MB adsorbents. The proof-of-principle investigation of NiO amorphous nanophase demonstrated the broad applicability of this methodology for obtaining new super dyes adsorbents. PMID:25761448

  15. Super adsorption capability from amorphousization of metal oxide nanoparticles for dye removal

    NASA Astrophysics Data System (ADS)

    Li, L. H.; Xiao, J.; Liu, P.; Yang, G. W.

    2015-03-01

    Transitional metal oxide nanoparticles as advanced environment and energy materials require very well absorption performance to apply in practice. Although most metal oxides are based on crystalline, high activities can also be achieved with amorphous phases. Here, we reported the adsorption behavior and mechanism of methyl blue (MB) on the amorphous transitional metal oxide (Fe, Co and Ni oxides) nanoparticles, and we demonstrated that the amorphousization of transitional metal oxide (Fe, Co and Ni oxides) nanoparticles driven by a novel process involving laser irradiation in liquid can create a super adsorption capability for MB, and the maximum adsorption capacity of the fabricated NiO amorphous nanostructure reaches up to 10584.6 mgg-1, the largest value reported to date for all MB adsorbents. The proof-of-principle investigation of NiO amorphous nanophase demonstrated the broad applicability of this methodology for obtaining new super dyes adsorbents.

  16. Super adsorption capability from amorphousization of metal oxide nanoparticles for dye removal.

    PubMed

    Li, L H; Xiao, J; Liu, P; Yang, G W

    2015-01-01

    Transitional metal oxide nanoparticles as advanced environment and energy materials require very well absorption performance to apply in practice. Although most metal oxides are based on crystalline, high activities can also be achieved with amorphous phases. Here, we reported the adsorption behavior and mechanism of methyl blue (MB) on the amorphous transitional metal oxide (Fe, Co and Ni oxides) nanoparticles, and we demonstrated that the amorphousization of transitional metal oxide (Fe, Co and Ni oxides) nanoparticles driven by a novel process involving laser irradiation in liquid can create a super adsorption capability for MB, and the maximum adsorption capacity of the fabricated NiO amorphous nanostructure reaches up to 10584.6?mgg(-1), the largest value reported to date for all MB adsorbents. The proof-of-principle investigation of NiO amorphous nanophase demonstrated the broad applicability of this methodology for obtaining new super dyes adsorbents. PMID:25761448

  17. Energy Cascades, Excited State Dynamics, and Photochemistry in Cob(III)alamins and Ferric Porphyrins.

    PubMed

    Rury, Aaron S; Wiley, Theodore E; Sension, Roseanne J

    2015-03-17

    Porphyrins and the related chlorins and corrins contain a cyclic tetrapyrrole with the ability to coordinate an active metal center and to perform a variety of functions exploiting the oxidation state, reactivity, and axial ligation of the metal center. These compounds are used in optically activated applications ranging from light harvesting and energy conversion to medical therapeutics and photodynamic therapy to molecular electronics, spintronics, optoelectronic thin films, and optomagnetics. Cobalt containing corrin rings extend the range of applications through photolytic cleavage of a unique axial carbon-cobalt bond, permitting spatiotemporal control of drug delivery. The photochemistry and photophysics of cyclic tetrapyrroles are controlled by electronic relaxation dynamics including internal conversion and intersystem crossing. Typically the electronic excitation cascades through ring centered ??* states, ligand to metal charge transfer (LMCT) states, metal to ligand charge transfer (MLCT) states, and metal centered states. Ultrafast transient absorption spectroscopy provides a powerful tool for the investigation of the electronic state dynamics in metal containing tetrapyrroles. The UV-visible spectrum is sensitive to the oxidation state, electronic configuration, spin state, and axial ligation of the central metal atom. Ultrashort broadband white light probes spanning the range from 270 to 800 nm, combined with tunable excitation pulses, permit the detailed unravelling of the time scales involved in the electronic energy cascade. State-of-the-art theoretical calculations provide additional insight required for precise assignment of the states. In this Account, we focus on recent ultrafast transient absorption studies of ferric porphyrins and corrin containing cob(III)alamins elucidating the electronic states responsible for ultrafast energy cascades, excited state dynamics, and the resulting photoreactivity or photostability of these compounds. Iron tetraphenyl porphyrin chloride (Fe((III))TPPCl) exhibits picosecond decay to a metal centered d ? d* (4)T state. This state decays on a ca. 16 ps time scale in room temperature solution but persists for much longer in a cryogenic glass. The photoreactivity of the (4)T state may lead to novel future applications for these compounds. In contrast, the nonplanar cob(III)alamins contain two axial ligands to the central cobalt atom. The upper axial ligand can be an alkyl group as in the two biologically active coenzymes or a nonalkyl ligand such as -CN in cyanocobalamin (vitamin B12) or -OH in hydroxocobalamin. The electronic structure, energy cascade, and bond cleavage of these compounds is sensitive to the details of the axial ligand. Nonalkylcobalamins exhibit ultrafast internal conversion to a low-lying state of metal to ligand or ligand to metal charge transfer character. The compounds are generally photostable with ground state recovery complete on a time scale of 2-7 ps in room temperature aqueous solution. Alkylcobalamins exhibit ultrafast internal conversion to an S1 state of d/? ? ?* character. Most compounds undergo bond cleavage from this state with near unit quantum yield within ?100 ps. Recent theoretical calculations provide a potential energy surface accounting for these observations. Conformation dependent mixing of the corrin ? and cobalt d orbitals plays a significant role in the observed photochemistry and photophysics. PMID:25741574

  18. Non-transferrin-bound iron in the serum of hemodialysis patients who receive ferric saccharate: no correlation to peroxide generation.

    PubMed

    Scheiber-Mojdehkar, Barbara; Lutzky, Barbara; Schaufler, Roland; Sturm, Brigitte; Goldenberg, Hans

    2004-06-01

    Intravenous iron (iv.Fe) is used to optimize response to recombinant human erythropoietin (r-HuEPO) in ESRD, but no consensus exists with respect to the best regimen to avoid transferrin "oversaturation," oxidative stress, and the occurrence of non-transferrin-bound iron (NTBI). Iv.Fe was stopped for 1 wk in 35 hemodialysis (HD) patients who were routinely receiving iv.Fe and r-HuEPO. The iv.Fe group received 100 mg of ferric saccharate (Venofer) at the end of the first HD session, whereas the time-control group was treated under the same conditions but received no iv.Fe. Serum samples were taken before the first HD session, immediately and 60 min after iv.Fe administration, and before the next HD session. Sera were analyzed for NTBI and peroxides; transferrin saturation was analyzed by urea-PAGE and Western blot. In an in vitro model system with HepG2 cells, the effects of ESRD serum on the labile iron pool (LIP) were assayed using the fluorescence calcein assay. NTBI significantly increased after iv.Fe-administration and returned to baseline values before the next HD-session. There was a shift from apo- to monoferric transferrin, but no "oversaturation" of transferrin after iv.Fe-treatment. Peroxides increased in both groups after HD. Hemodialysis decreased bioavailable iron for the LIP in HepG2-cells, whereas serum of iv.Fe-treated HD patients highly increased the LIP in these cells. A total of 100 mg of iv.Fe led to NTBI generation but not to an oversaturation of transferrin. Peroxide concentrations significantly increased during HD but were not correlated to iv.Fe administration and seemed to result from other sources of oxidative stress related to HD. NTBI can enter liver cells and increase the potentially harmful LIP. PMID:15153577

  19. An Interpretation of the Magnetic Properties of some Iron-Oxide Powders

    Microsoft Academic Search

    W P Osmond

    1952-01-01

    The observed magnetic properties of fine dispersed powders of the ferromagnetic iron oxides are discussed in the light of modern theories of the magnetization of ferrites and of ferromagnetics containing non-magnetic inclusions. The individual powder particles are shown to be probably of single-domain size, and the relative coercivities of ?-ferric oxide powders of nearly spherical and of markedly acicular grains

  20. Electrical and optical properties of ferric doped PVA-PVP-PPy composite films

    NASA Astrophysics Data System (ADS)

    Patil, Ravikumar V.; Ranganath, M. R.; Lobo, Blaise

    2013-02-01

    The analysis of experimental optical spectra & electrical properties of PVA-PVP-PPy composite films is discussed in this paper. The optical parameters like activation energy of optical transitions and the optical band gap for direct and indirect allowed transitions were determined for PVA-PVP-PPy composite films doped with different concentrations of ferric chloride. The optical band gap showed best fit for indirect allowed transitions, and there is a decrease in the optical band gap with increase in concentration of ferric chloride. The DC electrical properties of these films indicated agreement with Mott's Variable Range Hopping Model in three dimensions. The width of the forbidden band gap was determined from the Arrhenius relation after experimentally studying in-situ, the variation of DC electrical conductivity with temperature.

  1. Determination of iron-ligand bond lengths in ferric and ferrous horse heart cytochrome c using multiple-scattering analyses of XAFS data

    SciTech Connect

    Cheng, M.C.; Rich, A.M.; Armstrong, R.S.; Ellis, P.J.; Lay, P.A.

    1999-12-13

    Cytochrome c (cyt c) is a small heme protein (MW 12 384) that functions as a biological electron-transfer agent. It consists of a single polypeptide chain and a prosthetic heme group and provides a pathway for the transfer of electrons from cyt c reductase to cyt c oxidase in the mitochondrial respiratory chain (oxidative phosphorylation). The protein participates in oxidation-reduction reactions with the heme iron alternating between the oxidized (ferric, Fe{sup III}) state and the reduced (ferrous, Fe{sup II}) state. X-ray absorption fine structure (XAFS) data were obtained from frozen aqueous solutions (10 K) of horse heart ferri- and ferrocyt c. Models of the structure about the Fe center were refined to optimize the fit between the observed XAFS in the range 0 {le} k {le} 16.3 {angstrom}{sup {minus}1} and the XAFS calculated using both single-scattering (SS) and multiple-scattering (MS) calculations. The bond lengths obtained are more accurate and precise than those determined previously for cyt c from various species using X-ray crystallography. The Fe-N bond lengths are 1.98--1.99 {angstrom} for both oxidation states of cyt c. The Fe-S bond of derricyt c (2.33 {angstrom}) is significantly longer than that of ferrocyt c (2.29 {angstrom}). The small changes in the bond lengths are consistent with the small reorganizational energy required for the fast electron-transfer reaction of cyt c.

  2. Experimental determination of the phase boundary between kornelite and pentahydrated ferric sulfate at 0.1MPa

    USGS Publications Warehouse

    Kong, W.G.; Wang, A.; Chou, I.-Ming

    2011-01-01

    Recent findings of various ferric sulfates on Mars emphasize the importance of understanding the fundamental properties of ferric sulfates at temperatures relevant to that of Martian surface. In this study, the phase boundary between kornelite (Fe2(SO4)3.7H2O) and pentahydrated ferric sulfate (Fe2(SO4)3.5H2O) was experimentally determined using the humidity-buffer technique together with gravimetric measurements and Raman spectroscopy at 0.1MPa in the 36-56??C temperature range. Through the thermodynamic analysis of our experimental data, the enthalpy change (-290.8??0.3kJ/mol) and the Gibbs free energy change (-238.82??0.02kJ/mol) for each water molecule of crystallization in the rehydration of pentahydrated ferric sulfate to kornelite were obtained. ?? 2011 Elsevier B.V.

  3. In situ XANES Spectroscopic Investigation of the Pre-Reduction of Iron-Based Catalysts for Non-Oxidative Alkane Dehydrogenation

    SciTech Connect

    Huggins, F.; Shen, W; Cprek, N; Shah, N; Marinkovic, N; Huffman, G

    2008-01-01

    The reduction in a methane atmosphere of two as-prepared ferric oxide catalysts for the non-oxidative dehydrogenation of alkanes has been investigated by in situ X-ray absorption near-edge structure (XANES) spectroscopy using a novel X-ray transmission reaction cell. The two catalysts were prepared by different synthesis methods (incipient wetness and nanoparticle impregnation) and were supported on Al-substituted magnesium oxide obtained by decomposition of a synthetic hydrotalcite. The reduction of the ferric oxides by methane was followed by iron XANES spectroscopy at temperatures up to 650 C complemented by a residual gas analyzer (RGA) used to track changes in the product gas. Results showed that the ferric oxides in the two catalysts underwent a stepwise reduction to first ferrous oxide, releasing mainly H{sub 2}O in the case of the nanoparticle catalyst but H{sub 2} and CO in the case of the incipient wetness formulation at temperatures between 200 and 550 C, and then more slowly to metallic iron at higher temperatures. Reaction of the ferrous oxide with the support to form magnesiowstite also occurred in conjunction with the reduction. This in situ investigation confirms that metallic iron is the active catalytic phase for alkane dehydrogenation and that observations of ferric iron in samples investigated at room temperature after reduction and reaction are most likely due to re-oxidation of the iron in the catalyst upon exposure to air rather than incomplete reduction of the original ferric iron in the catalyst.

  4. Adsorption of uranyl onto ferric oxyhydroxides: Application of the surface complexation site-binding model

    Microsoft Academic Search

    Ching-Kuo Daniel Hsi; Donald Langmuir

    1985-01-01

    Uranyl adsorption was measured from aqueous electrolyte solutions onto well-characterized goethite, amorphous ferric oxyhydroxide, and hematite sols at 25°C. Adsorption was studied at a total uranyl concentration of 10 -5 M, (dissolved uranyl 10 -5 to 10 -8 M) as a function of solution pH, ionic strength and electrolyte concentrations, and of competing cations and carbonate complexing. Solution pHs ranged

  5. Removal of microorganisms from water by columns containing sand coated with ferric and aluminum hydroxides

    Microsoft Academic Search

    Jerzy Lukasik; Yueh-Fung Cheng; Fuhua Lu; Mark Tamplin; Samuel R. Farrah

    1999-01-01

    Tap water seeded with different microorganisms or untreated waste water was passed through columns containing sand modified by the in situ precipitation of metallic hydroxides or unmodified sand. Columns (35.5×5.0cm) packed with 1kg of sand modified with a combination of ferric and aluminum hydroxide removed greater than 99% of Escherichia coli, Vibrio cholerae, poliovirus 1 and coliphage MS-2 from dechlorinated

  6. Soil factors influencing ferric hydroxide plaque formation on roots of Typha latifolia L

    Microsoft Academic Search

    S. M. Macfie; A. A. Crowder

    1987-01-01

    The amount of ferric hydroxide plaque deposited onTypha latifolia roots varied between wetlands submerged throughout the growing season. Plaque formation was positively correlated with extractable\\u000a iron in the substrate and pH, and negatively correlated with the percent organic matter and percent inorganic carbonates in\\u000a the soil. All the above correlations were significant but weak, and in a stepwise regression analysis

  7. Highly Ordered LB Films of a Novel Ferric Schiff Base Complex

    Microsoft Academic Search

    Kezhi Wang; Masa-Aki Haga; Hideaki Monjushiro

    1999-01-01

    An amphiphlic ferric Schiff base complex, FeLCl·2H2O (L = N,N?-bis-(1-phenyl-3-methyl-4-octadecylidene-pyrazone-5-one)ethylenediamine), is newly synthesized and characterized. Surface pressure-area isotherm on pure water subphase of the complex shows stable Langmuir film-formation. UV-visible spectroscopy and low-angle x-ray diffraction indicate that LB films transferred on hydrophilic glass are of highly ordered structure.

  8. Microscale speciation of arsenic and iron in ferric-based sorbents subjected to simulated landfill conditions

    PubMed Central

    Root, Robert A.; Fathordoobadi, Sahar; Alday, Fernando; Ela, Wendell; Chorover, Jon

    2013-01-01

    During treatment for potable use, water utilities generate arsenic-bearing ferric wastes that are subsequently dispatched to landfills. The biogeochemical weathering of these residuals in mature landfills affects the potential mobilization of sorbed arsenic species via desorption from solids subjected to phase transformations driven by abundant organic matter and bacterial activity. Such processes are not simulated with the Toxicity Characteristic Leaching Procedure (TCLP) currently used to characterize hazard. To examine the effect of sulfate on As retention in landfill leachate, columns of As(V) loaded amorphous ferric hydroxide were reacted biotically at two leachate sulfate concentrations (0.064 mM and 2.1 mM). After 300 d, ferric sorbents were reductively dissolved. Arsenic released to porewaters was partially co-precipitated in mixed-valent secondary iron phases whose speciation was dependent on sulfate concentration. As and Fe XAS showed that, in the low sulfate column, 75–81% of As(V) was reduced to As(III), and 53–68% of the Fe(III) sorbent was transformed, dominantly to siderite and green rust. In the high sulfate column, Fe(III) solids were reduced principally to FeS(am), whereas As(V) was reduced to a polymeric sulfide with local atomic structure of realgar. Multi-energy micro-X-ray fluorescence (ME-?XRF) imaging at Fe and As K-edges showed that As formed surface complexes with ferrihydrite > siderite > green rust in the low sulfate column; while discrete realgar-like phases formed in the high sulfate systems. Results indicate that landfill sulfur chemistry exerts strong control over the potential mobilization of As from ferric sorbent residuals by controlling secondary As and Fe sulfide co-precipitate formation. PMID:24102155

  9. Repeat radiation synovectomy with dysprosium 165-ferric hydroxide macroaggregates in rheumatoid knees unresponsive to initial injection

    SciTech Connect

    Vella, M.; Zuckerman, J.D.; Shortkroff, S.; Venkatesan, P.; Sledge, C.B.

    1988-06-01

    Because of failure to fully respond to an initial intraarticular injection of dysprosium 165-ferric hydroxide macroaggregates, 17 patients with seropositive rheumatoid arthritis underwent repeat radiation synovectomy using this agent. Of the 13 patients who were evaluated 1 year later, 54% (7 knees) had good results, 31% (4 knees) had fair results, and 15% (2 knees) had poor results. The initial lack of significant benefit from radiation synovectomy did not appear to preclude a favorable response to a second injection.

  10. Characteristics and kinetics of phosphate adsorption on dewatered ferric-alum residuals

    Microsoft Academic Search

    Changhui Wang; Wei Guo; Binghui Tian; Yuansheng Pei; Kejiang Zhang

    2011-01-01

    The characteristics and kinetics of phosphate (P) adsorption on dewatered ferric-alum water treatment residuals (Fe-Al-WTRs) have been investigated. The existence of both aluminum (Al) and iron (Fe) in the residuals can result in significantly high P adsorption capacities. The P adsorption kinetics of Fe-Al-WTRs exhibited an initial rapid phase, followed by a slower phase. This could be described by three

  11. Equivalent bioavailability of iron from ferrous salts and a ferric polymaltose complex. Clinical and experimental studies.

    PubMed

    Jacobs, P

    1987-01-01

    In both experimental animals and human subjects iron absorption over a wide dosage range was quantitatively equivalent from ferrous salts and a ferric polymaltose complex under basal conditions. The comparable bioavailability was maintained when demand was increased by iron depletion or erythroid stimulation and depressed by expansion of body stores or impaired erythropoiesis. This common pattern for iron retention from both salt and complex supports the interchangeable use of these products in therapy of absolute iron deficiency. PMID:3566865

  12. Role of Ferric Iron and Protons in Mg-Fe Interdiffusion in (Mg,Fe)O

    Microsoft Academic Search

    K. Otsuka; M. Longo; C. A. McCammon; S. Karato

    2010-01-01

    The knowledge of transport properties such as atomic diffusion, viscosity and electrical conductivity in the ferropericlase-magnesiowüstite solid solution, (Mg,Fe)O, is critical for understanding the dynamics of the lower mantle. Previous studies suggest that dominant positively-charged point defects in (Mg,Fe)O may change with pressure: ferric iron (Fe3+) dominates at low pressure while protons (H+) may dominate at high pressure. Consequently, the

  13. Ferric and cupric ions requirement for DNA single-strand breakage by H2O2.

    PubMed

    Tachon, P

    1989-01-01

    Hydrogen peroxide (H2O2), was able to nick the replicative form of the phage fd, without the addition of a reducing agent or of a metal. This DNA single-strand breakage decreased with an increase of the ionic strength, suggesting that H2O2 reacted with traces of metal bound to DNA. When cupric of ferric ions were added, the rate of DNA single-strand breakage by H2O2 greatly increased and it was 20-30 times faster with cupric than with ferric ions. The addition of EDTA at an equimolar ratio or in excess of metal prevented partially DNA single-strand cleavage by H2O2 in the presence of ferric ions and completely when cupric ions were used. Superoxide dismutase prevented DNA single-strand breakage by H2O2 and ferric ions. On the contrary, with cupric ions and H2O2, the addition of superoxide dismutase increased the rate of DNA single-strand breakage. That superoxide dismutase was acting catalytically was shown by the loss of its effects after heat inactivation of the enzyme. The results of the present study show that besides its involvement in the Fenton reaction, H2O2 is able to reduce the metal bound to DNA, generating the superoxide anion radical or/and its protonated form, the perhydroxyl radical involved in DNA nicking. On the other hand, the ability of cuprous ions unlike ferrous ions to dismutate the superoxide radical may explain some differences observed between iron and copper in the DNA single-strand breakage by H2O2. PMID:2509299

  14. Olfactory ferric and ferrous iron absorption in iron-deficient rats

    PubMed Central

    Ruvin Kumara, V. M.

    2012-01-01

    The absorption of metals from the nasal cavity to the blood and the brain initiates an important route of occupational exposures leading to health risks. Divalent metal transporter-1 (DMT1) plays a significant role in the absorption of intranasally instilled manganese, but whether iron uptake would be mediated by the same pathway is unknown. In iron-deficient rats, blood 59Fe levels after intranasal administration of the radioisotope in the ferrous form were significantly higher than those observed for iron-sufficient control rats. Similar results were obtained when ferric iron was instilled intranasally, and blood levels of 59Fe were even greater in the iron-deficient rats compared with the amount of ferrous iron absorbed. Experiments with Belgrade (b/b) rats showed that DMT1 deficiency limited ferric iron uptake from the nasal cavity to the blood compared with +/b controls matched for iron deficiency. These results indicate that olfactory uptake of ferric iron by iron-deficient rats involves DMT1. Western blot experiments confirmed that DMT1 levels are significantly higher in iron-deficient rats compared with iron-sufficient controls in olfactory tissue. Thus the molecular mechanism of olfactory iron absorption is regulated by body iron status and involves DMT1. PMID:22492739

  15. Evolution of the Ferric Reductase Domain (FRD) Superfamily: Modularity, Functional Diversification, and Signature Motifs

    PubMed Central

    Zhang, Xuezhi; Krause, Karl-Heinz; Xenarios, Ioannis; Soldati, Thierry; Boeckmann, Brigitte

    2013-01-01

    A heme-containing transmembrane ferric reductase domain (FRD) is found in bacterial and eukaryotic protein families, including ferric reductases (FRE), and NADPH oxidases (NOX). The aim of this study was to understand the phylogeny of the FRD superfamily. Bacteria contain FRD proteins consisting only of the ferric reductase domain, such as YedZ and short bFRE proteins. Full length FRE and NOX enzymes are mostly found in eukaryotic cells and all possess a dehydrogenase domain, allowing them to catalyze electron transfer from cytosolic NADPH to extracellular metal ions (FRE) or oxygen (NOX). Metazoa possess YedZ-related STEAP proteins, possibly derived from bacteria through horizontal gene transfer. Phylogenetic analyses suggests that FRE enzymes appeared early in evolution, followed by a transition towards EF-hand containing NOX enzymes (NOX5- and DUOX-like). An ancestral gene of the NOX(1-4) family probably lost the EF-hands and new regulatory mechanisms of increasing complexity evolved in this clade. Two signature motifs were identified: NOX enzymes are distinguished from FRE enzymes through a four amino acid motif spanning from transmembrane domain 3 (TM3) to TM4, and YedZ/STEAP proteins are identified by the replacement of the first canonical heme-spanning histidine by a highly conserved arginine. The FRD superfamily most likely originated in bacteria. PMID:23505460

  16. The effects of pH regulation upon the release of sulfate from ferric precipitates formed in acid mine drainage

    Microsoft Academic Search

    Seth Rose; W. Crawford Elliott

    2000-01-01

    `Batch experiments' (25:1 v:w) were used to test the effects of pH upon the release of SO?24 from ferric precipitates formed in acid mine drainage (AMD) in southeastern Kentucky. Analytical grade CaO [`quicklime'], Ca(OH)2 [hydrated lime] and CaCO3 [referred to as `limestone'] were used as alkalinity generating agents and were mixed with ferric precipitates composed of amorphous iron oxyhydroxides, jarosite

  17. Thermal and Evolved Gas Analysis of "Nanophase" Carbonates: Implications for Thermal and Evolved Gas Analysis on Mars Missions

    NASA Technical Reports Server (NTRS)

    Lauer, Howard V., Jr.; Archer, P. D., Jr.; Sutter, B.; Niles, P. B.; Ming, Douglas W.

    2012-01-01

    Data collected by the Mars Phoenix Lander's Thermal and Evolved Gas Analyzer (TEGA) suggested the presence of calcium-rich carbonates as indicated by a high temperature CO2 release while a low temperature (approx.400-680 C) CO2 release suggested possible Mg- and/or Fe-carbonates [1,2]. Interpretations of the data collected by Mars remote instruments is done by comparing the mission data to a database on the thermal properties of well-characterized Martian analog materials collected under reduced and Earth ambient pressures [3,4]. We are proposing that "nano-phase" carbonates may also be contributing to the low temperature CO2 release. The objectives of this paper is to (1) characterize the thermal and evolved gas proper-ties of carbonates of varying particle size, (2) evaluate the CO2 releases from CO2 treated CaO samples and (3) examine the secondary CO2 release from reheated calcite of varying particle size.

  18. THE EFFECT OF OXIDANTS ON THE PROPERTIES OF FE (III) PARTICLES AND SUSPENSIONS FORMED FROM THE OXIDATION OF FE (II)

    EPA Science Inventory

    Oxidation of Fe(II) to Fe(III) is an important reaction in drinking water treatment and distribution systems, and the ferric particles that form are a major source of consumer complaints of colored water. Ferrous iron is found naturally in many ground waters and can be released ...

  19. The intermetalloid cluster [(Cp*AlCu)6H4], embedding a Cu6 core inside an octahedral Al6 shell: molecular models of Hume-Rothery nanophases.

    PubMed

    Ganesamoorthy, Chelladurai; Weßing, Jana; Kroll, Clarissa; Seidel, Rüdiger W; Gemel, Christian; Fischer, Roland A

    2014-07-21

    Defined molecular models for the surface chemistry of Hume-Rothery nanophases related to catalysis are very rare. The Al-Cu intermetalloid cluster [(Cp*AlCu)6H4] was selectively obtained from the clean reaction of [(Cp*Al)4] and [(Ph3PCuH)6]. The stronger affinity of Cp*Al towards Cu sweeps the phosphine ligands from the copper hydride precursor and furnishes an octahedral Al6 cage to encapsulate the Cu6 core. The resulting hydrido cluster M12H4 reacts with benzonitrile to give the stoichiometric hydrometalation product [(Cp*AlCu)6H3(N=CHPh)]. PMID:24962074

  20. Process for the synthesis of nanophase dispersion-strengthened aluminum alloy

    DOEpatents

    Barbour, John C. (Albuquerque, NM); Knapp, James Arthur (Albuquerque, NM); Follstaedt, David Martin (Albuquerque, NM); Myers, Samuel Maxwell (Albuquerque, NM)

    1998-12-15

    A process for fabricating dispersion-strengthened ceramic-metal composites is claimed. The process comprises in-situ interaction and chemical reaction of a metal in gaseous form with a ceramic producer in plasma form. Such composites can be fabricated with macroscopic dimensions. Special emphasis is placed on fabrication of dispersion-strengthened aluminum oxide-aluminum composites, which can exhibit flow stresses more characteristic of high strength steel.

  1. Cost-utility of ferric carboxymaltose (Ferinject®) for iron-deficiency anemia patients with chronic heart failure in South Korea

    PubMed Central

    2014-01-01

    Background Iron-deficiency anemia (IDA) is prevalent in patients with advanced chronic heart failure (CHF). It affects the patients’ overall physical condition and is suggested as a strong outcome predictor in CHF. Recent clinical trials suggested that intravenous iron supplementation improves CHF functional status and quality of life. The aim of this study was to assess the cost-effectiveness of ferric carboxymaltose(FCM) in CHF patients with IDA. Methods Ferric carboxymaltose, an intravenous iron preparation, was compared with placebo. The target population comprised CHF patients with IDA in hospital and outpatient care settings. We conducted this study from the Korean healthcare payers’ perspective with a time horizon of 24 weeks. One clinical trial provided the clinical outcomes of ferric carboxymaltose therapy. The improvement rates of the New York Heart Association (NYHA) functional class in the placebo and ferric carboxymaltose groups were used to estimate effectiveness in the base-case model. We also conducted a scenario 2 analysis using quality of life investigated in the clinical trial. A panel survey was conducted to obtain the ratio of healthcare resource use based on NYHA class in Korea. Cost-effectiveness was expressed as incremental cost (US dollars) per quality-adjusted life-year (QALY) gained. Results In the base-case analysis, the incremental cost-effectiveness ratio (ICER) of ferric carboxymaltose compared with placebo was $22,192 (?25,010,451) per QALY gained. The sensitivity analysis showed robust results, with the ICERs of ferric carboxymaltose ranging from $5,156 to $29,796 per QALY gained. In the scenario 2 analysis, ICER decreased to $12,598 (?14,198,501) per QALY gained. Conclusions Iron repletion with ferric carboxymaltose for IDA in CHF patients was cost-effective compared with placebo. PMID:25278814

  2. Evidence for regulatory control of iron uptake from ferric maltol across the small intestine of the rat.

    PubMed Central

    Barrand, M. A.; Callingham, B. A.

    1991-01-01

    1. 59Fe absorption from the novel iron compound, ferric maltol, was studied in rats pretreated twice daily for two weeks with non-radioactive ferric maltol in oral doses containing 7 mg elemental iron. Tissue accumulation of 59Fe 2 h after administration of radioactive ferric maltol into the stomach was significantly lower in iron pretreated animals than in saline-treated controls. 2. 59Fe uptake from ferric maltol into isolated fragments of ileum and of duodenum was of similar magnitude in control animals but in iron-treated animals, duodenal uptake was significantly lower than that of the ileum. 3. Absorption of 59Fe was also investigated in anaesthetized rats after intestinal perfusion with saline (controls) or with 5 mM chenodeoxycholate to render the intestines more permeable. 4. Changes in permeability of the small intestine were monitored by estimating the amount of [14C]-mannitol absorbed and fluid secreted with reference to the non-absorbable [3H]-inulin in the perfusate effluents. 5. Despite the increased permeability of the intestines after bile salt treatment, there was little difference from control in the tissue accumulation of 59Fe from ferric maltol 2 h after intraduodenal administration. However 59Fe absorption from ferrous sulphate was significantly increased after bile salt treatment. 6. Gel filtration profiles of plasma made 5 and 60 min after intraduodenal administration of [59Fe]-ferric [3H]-maltol demonstrated that metal and ligand do not enter the circulation as the complex even when intestinal permeability is increased. 7. Uptake of 59Fe was investigated in isolated fragments of rat small intestine after saline or bile salt perfusion. Although 59Fe uptake from ferric maltol was somewhat greater in the bile salt-treated intestinal fragments, saturable kinetics were still observed.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1 Figure 4 PMID:2015422

  3. Resonant inelastic X-ray scattering on ferrous and ferric bis-imidazole porphyrin and cytochrome c: nature and role of the axial methionine-Fe bond.

    PubMed

    Kroll, Thomas; Hadt, Ryan G; Wilson, Samuel A; Lundberg, Marcus; Yan, James J; Weng, Tsu-Chien; Sokaras, Dimosthenis; Alonso-Mori, Roberto; Casa, Diego; Upton, Mary H; Hedman, Britt; Hodgson, Keith O; Solomon, Edward I

    2014-12-31

    Axial Cu-S(Met) bonds in electron transfer (ET) active sites are generally found to lower their reduction potentials. An axial S(Met) bond is also present in cytochrome c (cyt c) and is generally thought to increase the reduction potential. The highly covalent nature of the porphyrin environment in heme proteins precludes using many spectroscopic approaches to directly study the Fe site to experimentally quantify this bond. Alternatively, L-edge X-ray absorption spectroscopy (XAS) enables one to directly focus on the 3d-orbitals in a highly covalent environment and has previously been successfully applied to porphyrin model complexes. However, this technique cannot be extended to metalloproteins in solution. Here, we use metal K-edge XAS to obtain L-edge like data through 1s2p resonance inelastic X-ray scattering (RIXS). It has been applied here to a bis-imidazole porphyrin model complex and cyt c. The RIXS data on the model complex are directly correlated to L-edge XAS data to develop the complementary nature of these two spectroscopic methods. Comparison between the bis-imidazole model complex and cyt c in ferrous and ferric oxidation states show quantitative differences that reflect differences in axial ligand covalency. The data reveal an increased covalency for the S(Met) relative to N(His) axial ligand and a higher degree of covalency for the ferric states relative to the ferrous states. These results are reproduced by DFT calculations, which are used to evaluate the thermodynamics of the Fe-S(Met) bond and its dependence on redox state. These results provide insight into a number of previous chemical and physical results on cyt c. PMID:25475739

  4. Size fractionation characterisation of removed organics in reverse osmosis concentrates by ferric chloride.

    PubMed

    Bagastyo, A Y; Keller, J; Batstone, D J

    2011-01-01

    Reverse osmosis membrane separation is the leading method for manufacturing potable purified water. It also produces a concentrate stream, namely reverse osmosis concentrates (ROC), with 10-20% of the water, and almost all other compounds. One method for further treating this stream is by coagulation with ferric chloride. This study evaluates removed organics in ROC treated with ferric chloride. Fractionation with ultrafiltration membranes allows separation of organics based on a nominal molecular weight. A stirred cell system was applied for serial fractionation to classify organic compounds into six groups of < 0.5 kDa, 0.5-1 kDa, 1-3 kDa, 3-5 kDa, 5-10 kDa and > 10 kDa. The study found that raw ROC is rich in low molecular weight compounds (< 1 kDa) with almost 50% of the organics. These compounds include soluble microbial products (SMPs) and smaller humic and fulvic acids as indicated by fluorescence scanning. Conversely, colour was mostly contributed by medium to large molecules of humic and fulvic acids (> 0.5 kDa). Organics and colour were reduced in all molecular groups at an optimum treatment dose 1.48 mM FeCl3 and a pH of 5. However, ferric seemed to effectively remove colour in all size ranges while residual nitrogen was found mostly in the < 1 kDa sizes. Further, the fluorescence indicated that larger humic and fulvic acids were removed with considerable SMPs remaining in the < 0.5 kDa. PMID:21902015

  5. Ferric Iron Reduction by Bacteria Associated with the Roots of Freshwater and Marine Macrophytes†

    PubMed Central

    King, G. M.; Garey, Meredith A.

    1999-01-01

    In vitro assays of washed, excised roots revealed maximum potential ferric iron reduction rates of >100 ?mol g (dry weight)?1 day?1 for three freshwater macrophytes and rates between 15 and 83 ?mol (dry weight)?1 day?1 for two marine species. The rates varied with root morphology but not consistently (fine root activity exceeded smooth root activity in some but not all cases). Sodium molybdate added at final concentrations of 0.2 to 20 mM did not inhibit iron reduction by roots of marine macrophytes (Spartina alterniflora and Zostera marina). Roots of a freshwater macrophyte, Sparganium eurycarpum, that were incubated with an analog of humic acid precursors, anthroquinone disulfate (AQDS), reduced freshly precipitated iron oxyhydroxide contained in dialysis bags that excluded solutes with molecular weights of >1,000; no reduction occurred in the absence of AQDS. Bacterial enrichment cultures and isolates from freshwater and marine roots used a variety of carbon and energy sources (e.g., acetate, ethanol, succinate, toluene, and yeast extract) and ferric oxyhydroxide, ferric citrate, uranate, and AQDS as terminal electron acceptors. The temperature optima for a freshwater isolate and a marine isolate were equivalent (approximately 32°C). However, iron reduction by the freshwater isolate decreased with increasing salinity, while reduction by the marine isolate displayed a relatively broad optimum salinity between 20 and 35 ppt. Our results suggest that by participating in an active iron cycle and perhaps by reducing humic acids, iron reducers in the rhizoplane of aquatic macrophytes limit organic availability to other heterotrophs (including methanogens) in the rhizosphere and bulk sediments. PMID:10508065

  6. Ferric iron reduction by bacteria associated with the roots of freshwater and marine macrophytes.

    PubMed

    King, G M; Garey, M A

    1999-10-01

    In vitro assays of washed, excised roots revealed maximum potential ferric iron reduction rates of >100 micromol g (dry weight)(-1) day(-1) for three freshwater macrophytes and rates between 15 and 83 micromol (dry weight)(-1) day(-1) for two marine species. The rates varied with root morphology but not consistently (fine root activity exceeded smooth root activity in some but not all cases). Sodium molybdate added at final concentrations of 0.2 to 20 mM did not inhibit iron reduction by roots of marine macrophytes (Spartina alterniflora and Zostera marina). Roots of a freshwater macrophyte, Sparganium eurycarpum, that were incubated with an analog of humic acid precursors, anthroquinone disulfate (AQDS), reduced freshly precipitated iron oxyhydroxide contained in dialysis bags that excluded solutes with molecular weights of >1,000; no reduction occurred in the absence of AQDS. Bacterial enrichment cultures and isolates from freshwater and marine roots used a variety of carbon and energy sources (e.g., acetate, ethanol, succinate, toluene, and yeast extract) and ferric oxyhydroxide, ferric citrate, uranate, and AQDS as terminal electron acceptors. The temperature optima for a freshwater isolate and a marine isolate were equivalent (approximately 32 degrees C). However, iron reduction by the freshwater isolate decreased with increasing salinity, while reduction by the marine isolate displayed a relatively broad optimum salinity between 20 and 35 ppt. Our results suggest that by participating in an active iron cycle and perhaps by reducing humic acids, iron reducers in the rhizoplane of aquatic macrophytes limit organic availability to other heterotrophs (including methanogens) in the rhizosphere and bulk sediments. PMID:10508065

  7. Evolution of the ferric enterobactin receptor in gram-negative bacteria.

    PubMed

    Rutz, J M; Abdullah, T; Singh, S P; Kalve, V I; Klebba, P E

    1991-10-01

    Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis of iron-deficient and replete cell envelopes, 59Fe-siderophore uptake studies, and Western immunoblots and cytofluorimetric analyses with monoclonal antibodies (MAbs), we surveyed a panel of gram-negative bacteria to identify outer membrane proteins that are structurally related to the Escherichia coli K-12 ferric enterobactin receptor, FepA. Antibodies within the panel identified FepA epitopes that are conserved among the majority of the bacteria tested, as well as epitopes present in only a few of the strains. In general, epitopes of FepA that are buried in the outer membrane bilayer were more conserved among gram-negative bacteria than epitopes that are exposed on the bacterial cell surface. The surface topology and tertiary structure of FepA are quite similar in E. coli and Shigella flexneri but differ in Salmonella typhimurium. Of the 18 different genera tested, 94% of the bacteria transported ferric enterobactin, including members of the previously unrecognized genera Citrobacter, Edwardsiella, Enterobacter, Haemophilus, Hafnia, Morganella, Neisseria, Proteus, Providencia, Serratia, and Yersinia. The ferric enterobactin receptor contains at least one buried epitope, recognized by MAb 2 (C. K. Murphy, V. I. Kalve, and P. E. Klebba, J. Bacteriol. 172:2736-2746, 1990), that is conserved within the structure of an iron-regulated cell envelope protein in all the bacteria that we have surveyed. With MAb 2, we identified and determined the Mr of cell envelope antigens that are immunologically related to E. coli FepA in all the gram-negative bacteria tested. Collectively, the library of anti-FepA MAbs showed unique patterns of reactivity with the different bacteria, allowing identification and discrimination of species within the following gram-negative genera: Aeromonas, Citrobacter, Edwardsiella, Enterobacter, Escherichia, Haemophilus, Hafnia, Klebsiella, Morganella, Neisseria, Proteus, Providencia, Pseudomonas, Salmonella, Serratia, Shigella, Vibrio, and Yersinia. PMID:1717434

  8. Effects of ferric citrate injection on the composition of bile acids in rats.

    PubMed

    Noda, Y; Ogura, M; Edamatsu, R; Itoh, T; Yufu, K; Mori, A

    1993-09-01

    Ferric citrate was examined for its possible induction of acute and chronic changes in bile acids in rats. Three hours after a single intravenous Fe(III) injection both the biliary bile acid level and the percentage of cholic acid in bile were significantly higher in treated rats than in control rats. However, no significant difference was observed after treatment with the same daily dose for one week. The superoxide dismutase (SOD) activity in liver tissue increased in the chronic group. These results suggest that oxygen free radicals, mainly the hydroxyl radical, promote hydroxylation during bile acid biosynthesis by enhanced monooxygenase activity. PMID:8235071

  9. Kinetic and equilibrium constants of phytic acid and ferric and ferrous phytate derived from nuclear magnetic resonance spectroscopy.

    PubMed

    Heighton, Lynne; Schmidt, Walter F; Siefert, Ronald L

    2008-10-22

    Inositol phosphates are metabolically derived organic phosphates (P) that increasingly appear to be an important sink and source of P in the environment. Salts of myo-inositol hexakisdihydrogen phosphate (IHP) or more commonly phytate are the most common inositol phosphates in the environment. IHP resists acidic dephosphorylation and enzymatic dephosphorylation as ferric or ferrous IHP. Mobility of IHP iron complexes is potentially pH and redox responsive, making the time scale and environmental fate and transport of the P associated with the IHP of interest to the mass balance of phosphorus. Ferric and ferrous complexes of IHP were investigated by proton nuclear magnetic resonance spectroscopy ( (1)H NMR) and enzymatic dephosphorylation. Ferrous IHP was found to form quickly and persist for a longer period then ferric IHP. Dissociation constants derived from (1)H NMR experiments of chemically exchanging systems at equilibrium were 1.11 and 1.19 and formation constants were 0.90 and 0.84 for ferric and ferrous IHP, respectively. The recovery of P from enzymatic dephosphorylation of ferric and ferrous IHP was consistent with the magnitude of the kinetic and equilibrium rate constants. PMID:18798632

  10. Car–Parrinello molecular dynamics in the DFT + U formalism: Structure and energetics of solvated ferrous and ferric ions

    SciTech Connect

    Sit, P H L.; Cococcioni, Matteo; Marzari, Nicola N.

    2007-09-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car–Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT + U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexaaqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe–O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe–O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.

  11. Ferric carboxymaltose.

    PubMed

    Cada, Dennis J; Levien, Terri L; Baker, Danial E

    2014-01-01

    Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, call The Formulary at 800-322-4349. The January 2014 monograph topics are obinutuzumab, anti-inhibitor coagulant complex, macitentan, riociguat, and conjugated estrogens/bazedoxifene. The DUE/MUE is on conjugated estrogens/bazedoxifene. PMID:24421564

  12. Ferric Carboxymaltose

    PubMed Central

    Cada, Dennis J.; Levien, Terri L.; Baker, Danial E.

    2014-01-01

    Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, call The Formulary at 800-322-4349. The January 2014 monograph topics are obinutuzumab, anti-inhibitor coagulant complex, macitentan, riociguat, and conjugated estrogens/bazedoxifene. The DUE/MUE is on conjugated estrogens/bazedoxifene. PMID:24421564

  13. Iron sucrose and ferric carboxymaltose: no correlation between physicochemical stability and biological activity.

    PubMed

    Praschberger, Monika; Haider, Kathrin; Cornelius, Carolin; Schitegg, Markus; Sturm, Brigitte; Goldenberg, Hans; Scheiber-Mojdehkar, Barbara

    2015-02-01

    Intravenous iron preparations, like iron sucrose (IS) and ferric carboxymaltose (FCM) differ in their physicochemical stability. Thus differences in storage and utilization can be expected and were investigated in a non-clinical study in liver parenchyma HepG2-cells and THP-1 macrophages as models for toxicological and pharmacological target cells. HepG2-cells incorporated significant amounts of IS, elevated the labile iron pool (LIP) and ferritin and stimulated iron release. HepG2-cells had lower basal cellular iron and ferritin content than THP-1 macrophages, which showed only marginal accumulation of IS and FCM. However, FCM increased the LIP up to twofold and significantly elevated ferritin within 24 h in HepG2-cells. IS and FCM were non-toxic for HepG2-cells and THP-1 macrophages were more sensitive to FCM compared to IS at all concentrations tested. In a cell-free environment redox-active iron was higher with IS than FCM. Biostability testing via assessment of direct transfer to serum transferrin did not reflect the chemical stability of the complexes (i.e., FCM > IS). Effect of vitamin C on mobilisation to transferrin was an increase with IS and interestingly a decrease with FCM. In conclusion, FCM has low bioavailability for liver parenchyma cells, therefore liver iron deposition is unlikely. Ascorbic acid reduces transferrin-chelatable iron from ferric carboxymaltose, thus effects on hepcidin expression should be investigated in clinical studies. PMID:25326244

  14. Arsenic removal from high-arsenic water by enhanced coagulation with ferric ions and coarse calcite.

    PubMed

    Song, S; Lopez-Valdivieso, A; Hernandez-Campos, D J; Peng, C; Monroy-Fernandez, M G; Razo-Soto, I

    2006-01-01

    Arsenic removal from high-arsenic water in a mine drainage system has been studied through an enhanced coagulation process with ferric ions and coarse calcite (38-74 microm) in this work. The experimental results have shown that arsenic-borne coagulates produced by coagulation with ferric ions alone were very fine, so micro-filtration (membrane as filter medium) was needed to remove the coagulates from water. In the presence of coarse calcite, small arsenic-borne coagulates coated on coarse calcite surfaces, leading the settling rate of the coagulates to considerably increase. The enhanced coagulation followed by conventional filtration (filter paper as filter medium) achieved a very high arsenic removal (over 99%) from high-arsenic water (5mg/l arsenic concentration), producing a cleaned water with the residual arsenic concentration of 13 microg/l. It has been found that the mechanism by which coarse calcite enhanced the coagulation of high-arsenic water might be due to attractive electrical double layer interaction between small arsenic-borne coagulates and calcite particles, which leads to non-existence of a potential energy barrier between the heterogeneous particles. PMID:16352327

  15. Oxygen reduction and lipid peroxidation by iron chelates with special reference to ferric nitrilotriacetate.

    PubMed

    Hamazaki, S; Okada, S; Li, J L; Toyokuni, S; Midorikawa, O

    1989-07-01

    A certain iron chelate, ferric nitrilotriacetate (Fe3+-NTA) is nephrotoxic and also carcinogenic to the kidney in mice and rats, a distinguishing feature not shared by other iron chelates tested so far. Iron-promoted lipid peroxidation is thought to be responsible for the initial events. We examined its ability to initiate lipid peroxidation in vitro in comparison with that of other ferric chelates. Chelation of Fe2+ by nitrilotriacetate (NTA) enhanced the autoxidation of Fe2+. In the presence of Fe2+-NTA, lipid peroxidation occurred as measured by the formation of conjugated diene in detergent-dispersed linoleate micelles, and by the formation of thiobarbituric acid-reactive substances in the liposomes of rat liver microsomal lipids. Addition of ascorbic acid to Fe3+-NTA solution promoted dose-dependent consumption of dissolved oxygen, which indicates temporary reduction of iron. On reduction, Fe3+-NTA initiated lipid peroxidation both in the linoleate micelles and in the liposomes. Fe3+-NTA also initiated NADPH-dependent lipid peroxidation in rat liver microsomes. Although other chelators used (deferoxamine, EDTA, diethylenetriaminepentaacetic acid, ADP) enhanced autoxidation, reduction by ascorbic acid, or in vitro lipid peroxidation of linoleate micelles or liposomal lipids, NTA was the sole chelator that enhanced all the reactions. PMID:2500058

  16. Ferric Citrate Hydrate as a Phosphate Binder and Risk of Aluminum Toxicity

    PubMed Central

    Gupta, Ajay

    2014-01-01

    Ferric citrate hydrate was recently approved in Japan as an oral phosphate binder to be taken with food for the control of hyperphosphatemia in patients with chronic kidney disease (CKD). The daily therapeutic dose is about 3 to 6 g, which comprises about 2 to 4 g of citrate. Oral citrate solubilizes aluminum that is present in food and drinking water, and opens the tight junctions in the intestinal epithelium, thereby increasing aluminum absorption and urinary excretion. In healthy animals drinking tap water, oral citrate administration increased aluminum absorption and, over a 4-week period, increased aluminum deposition in brain and bone by about 2- and 20-fold, respectively. Renal excretion of aluminum is impaired in patients with chronic kidney disease, thereby increasing the risk of toxicity. Based on human and animal studies it can be surmised that patients with CKD who are treated with ferric citrate hydrate to control hyperphosphatemia are likely to experience enhanced absorption of aluminum from food and drinking water, thereby increasing the risk of aluminum overload and toxicity. PMID:25341358

  17. Synovectomy of the rheumatoid knee using intra-articular injection of dysprosium-165-ferric hydroxide macroaggregates

    SciTech Connect

    Sledge, C.B.; Zuckerman, J.D.; Shortkroff, S.; Zalutsky, M.R.; Venkatesan, P.; Snyder, M.A.; Barrett, W.P.

    1987-09-01

    One hundred and eleven patients who had seropositive rheumatoid arthritis and persistent synovitis of the knee were treated with intra-articular injection of 270 millicuries of dysprosium-165 bound to ferric hydroxide macroaggregates. A two-year follow-up was available for fifty-nine of the treated knees. Thirty-nine had a good result; nine, a fair result; and eleven, a poor result. Of the twenty-five knees that had Stage-I radiographic changes, nineteen had a good result. Of the thirty-four knees that had Stage-II radiographic changes, twenty showed a good result. Systemic spread of the radioactivity from the injected joint was minimum. The mean whole-body dose was calculated to be 0.3 rad and that to the liver twenty-four hours after injection, 3.2 rads. The results indicated that dysprosium-165-ferric hydroxide macroaggregate is an effective agent for performing radiation synovectomy, particularly in knees that have Stage-I radiographic changes. Because of the minimum rate of systemic spread of the dysprosium-165, it offers a definite advantage over agents that previously have been used.

  18. Treatment of rheumatoid synovitis of the knee with intraarticular injection of dysprosium 165-ferric hydroxide macroaggregates

    SciTech Connect

    Sledge, C.B.; Zuckerman, J.D.; Zalutsky, M.R.; Atcher, R.W.; Shortkroff, S.; Lionberger, D.R.; Rose, H.A.; Hurson, B.J.; Lankenner, P.A. Jr.; Anderson, R.J.

    1986-02-01

    One hundred eight knees of 93 patients with seropositive rheumatoid arthritis and persistent synovitis of the knee were treated with an intraarticular injection of 270 mCi of dysprosium 165 bound to ferric hydroxide macroaggregate. Leakage of radioactivity from the injected joint was minimal. Mean leakage to the venous blood 3 hours after injection was 0.11% of the injected dose; this corresponds to a mean whole body dose of 0.2 rads. Mean leakage to the liver 24 hours after injection was 0.64% of the injected dose; this corresponds to a mean liver dose of 3.2 rads. In 7 additional patients examined, there was negligible or near negligible activity found in the draining inguinal lymph nodes. One-year followup was possible for 74 knees (63 patients). Sixty-one percent of the knees had good results, 23% had fair results, and 16% had poor results. There was a direct correlation between the radiographic stage and response to treatment. In knees with stage I radiographic changes, 72% showed good results; 93% showed improvement. In knees with stage II changes, 59% showed good results; 81% showed improvement. These preliminary results indicate that dysprosium 165-ferric hydroxide macroaggregate is an effective agent for radiation synovectomy. The low leakage rates observed offer a definite advantage over agents previously used.

  19. Ferric reductase of Saccharomyces cerevisiae: molecular characterization, role in iron uptake, and transcriptional control by iron.

    PubMed Central

    Dancis, A; Roman, D G; Anderson, G J; Hinnebusch, A G; Klausner, R D

    1992-01-01

    The principal iron uptake system of Saccharomyces cerevisiae utilizes a reductase activity that acts on ferric iron chelates external to the cell. The FRE1 gene product is required for this activity. The deduced amino acid sequence of the FRE1 protein exhibits hydrophobic regions compatible with transmembrane domains and has significant similarity to the sequence of the plasma membrane cytochrome b558 (the X-CGD protein), a critical component of a human phagocyte oxidoreductase, suggesting that FRE1 is a structural component of the yeast ferric reductase. FRE1 mRNA levels are repressed by iron. Fusion of 977 base pairs of FRE1 DNA upstream from the translation start site of an Escherichia coli lacZ reporter gene confers iron-dependent regulation on expression of beta-galactosidase in yeast. An 85-base-pair segment of FRE1 5' noncoding sequence contains a RAP1 binding site and a repeated sequence, TTTTTGCTCAYC; this segment is sufficient to confer iron-repressible transcriptional activity on heterologous downstream promoter elements. Images PMID:1570306

  20. Iron pharmacokinetics after administration of ferric-hydroxide-polymaltose complex in rats.

    PubMed

    Geisser, P; Müller, A

    1984-01-01

    This paper reports a study of the pharmacokinetics of ferrous sulphate and ferric-hydroxide-polymaltose complex (Hw 6400, Ferrum Hausmann) administered orally and intravenously to anaemic and non-anaemic rats of both sexes. Radiolabelled ferrous sulphate and ferric-hydroxide-polymaltose complex was used to study iron utilization after oral administration. Measurements of radioactivity in serum, packed red cells, whole blood, liver, kidney, spleen, bone and in some cases in the gastrointestinal tract were made following a range of dosages between 0.84 and 41.9 mg Fe/kg. No significant difference in bioavailability or iron utilization was found between the two iron preparations. Pharmacokinetic measurements following i.v. administration showed different distribution volumes, iron clearance and elimination constants for the two preparations. This difference in pharmacokinetic behaviour following oral administration, particularly in the case of non-anaemic rats, was confirmed by the observation that a 10- to 20 fold smaller dose of FeSO4 than of iron-polymaltose complex was required to achieve the same rise in serum iron. It is therefore not justifiable to draw conclusions about the bioavailability of chemically different iron preparations (iron salts and iron hydroxide complexes) on the basis of AUC values for serum iron increases observed in non-anaemic animals or human subjects. PMID:6543131

  1. Evaluation of polyaluminium ferric chloride (PAFC) as a composite coagulant for water and wastewater treatment.

    PubMed

    Gao, B; Yue, Q; Miao, J

    2003-01-01

    Coal gangue is a kind of waste from coal mine processing. Polyaluminium ferric chloride (PAFC), a new type of inorganic composite coagulant, was prepared by using the waste from the Mineral Bureau of Yanzhou, China, hydrochloric acid and calcium carbonate as raw materials. The relationship between the stability of ferric ion and the ionic strength of solution was investigated. The zeta potential of PAFC hydrolysis products of PAFC and the coagulation performances under different pH value were discussed. The turbidity removal properties of PAFC, polyaluminium (PAC) and polyferric sulfate (PFS) were compared, and the color removal effect of PAFC for the wastewater containing suspended dyes was also tested. In addition, the coagulation performance of PAFC for actual wastewaters from petrochemical plant, iron and steel plant, and coal mining processing was evaluated. The experimental results suggest that PAFC took a maximum value of zeta potential at about pH 5.8 on the positive side. Compared with PAC, PAFC gives better turbidity removal performance in the range of pH from 7.0 to 8.4. PAFC gives good color removal performance on suspension dyes. PAFC also gives good wastewater purifying results for the actual wastewater. Therefore, PAFC is a high-effect and stable water treatment agent. PMID:12578184

  2. Effect of ionic strength on ligand exchange kinetics between a mononuclear ferric citrate complex and siderophore desferrioxamine B

    NASA Astrophysics Data System (ADS)

    Ito, Hiroaki; Fujii, Manabu; Masago, Yoshifumi; Waite, T. David; Omura, Tatsuo

    2015-04-01

    The effect of ionic strength (I) on the ligand exchange reaction between a mononuclear ferric citrate complex and the siderophore, desferrioxamine B (DFB), was examined in the NaCl concentration range of 0.01-0.5 M, particularly focusing on the kinetics and mechanism of ligand exchange under environmentally relevant conditions. Overall ligand exchange rate constants were determined by spectrophotometrically measuring the time course of ferrioxamine B formation at a water temperature of 25 °C, pH 8.0, and citrate/Fe molar ratios of 500-5000. The overall ligand exchange rate decreased by 2-11-fold (depending on the citrate/Fe molar ratios) as I increased from approximately 0.01 to 0.5 M. In particular, a relatively large decrease was observed at lower I (<0.1 M). A ligand exchange model describing the effect of I on the ligand exchange rate via disjunctive and adjunctive pathways was developed by considering the pseudo-equilibration of ferric citrate complexes and subsequent ferrioxamine formation on the basis of the Eigen-Wilkins metal-ligand complexation theory. The model and experimental data consistently suggest that the adjunctive pathway (i.e., direct association of DFB with ferric mono- and di-citrate complexes following dissociation of citrate from the parent complexes) dominates in ferrioxamine formation under the experimental conditions used. The model also predicts that the higher rate of ligand exchange at lower I is associated with the decrease in the ferric dicitrate complex stability because of the relatively high electrical repulsion between ferric monocitrate and free citrate at lower I (note that the reactivity of ferric dicitrate with DFB is smaller than that for the monocitrate complex). Overall, the findings of this study contribute to the understanding of the potential effect of I on ligand exchange kinetics in natural waters and provide fundamental knowledge on iron transformation and bioavailability.

  3. Identification and Characterization of a Novel-type Ferric Siderophore Reductase from a Gram-positive Extremophile*

    PubMed Central

    Miethke, Marcus; Pierik, Antonio J.; Peuckert, Florian; Seubert, Andreas; Marahiel, Mohamed A.

    2011-01-01

    Iron limitation is one major constraint of microbial life, and a plethora of microbes use siderophores for high affinity iron acquisition. Because specific enzymes for reductive iron release in Gram-positives are not known, we searched Firmicute genomes and found a novel association pattern of putative ferric siderophore reductases and uptake genes. The reductase from the schizokinen-producing alkaliphile Bacillus halodurans was found to cluster with a ferric citrate-hydroxamate uptake system and to catalyze iron release efficiently from Fe[III]-dicitrate, Fe[III]-schizokinen, Fe[III]-aerobactin, and ferrichrome. The gene was hence named fchR for ferric citrate and hydroxamate reductase. The tightly bound [2Fe-2S] cofactor of FchR was identified by UV-visible, EPR, CD spectroscopy, and mass spectrometry. Iron release kinetics were determined with several substrates by using ferredoxin as electron donor. Catalytic efficiencies were strongly enhanced in the presence of an iron-sulfur scaffold protein scavenging the released ferrous iron. Competitive inhibition of FchR was observed with Ga(III)-charged siderophores with Ki values in the micromolar range. The principal catalytic mechanism was found to couple increasing Km and KD values of substrate binding with increasing kcat values, resulting in high catalytic efficiencies over a wide redox range. Physiologically, a chromosomal fchR deletion led to strongly impaired growth during iron limitation even in the presence of ferric siderophores. Inductively coupled plasma-MS analysis of ?fchR revealed intracellular iron accumulation, indicating that the ferric substrates were not efficiently metabolized. We further show that FchR can be efficiently inhibited by redox-inert siderophore mimics in vivo, suggesting that substrate-specific ferric siderophore reductases may present future targets for microbial pathogen control. PMID:21051545

  4. Microbial oxidation of ferrous iron in acid mine water at sulfur and iron-sulfide mine

    Microsoft Academic Search

    Norio Wakao; Yonekichi Sakurai; Hideo Shiota

    1977-01-01

    The microbial oxidation of ferrous iron in the acid mine water from the abandoned Matsuo sulfur and iron-sulfide mine area was investigated. The acid mine water had an extremely low pH value and contained a high concentration of ferrous iron (about 1,000 ppm). The ferrous iron was oxidized rapidly to the ferric form in the acid mine water. The oxidation

  5. Meta-analysis of efficacy and safety of intravenous ferric carboxymaltose (Ferinject) from clinical trial reports and published trial data

    PubMed Central

    2011-01-01

    Background Recommendations given for intravenous iron treatment are typically not supported by a high level of evidence. This meta-analysis addressed this by summarising the available date from clinical trials of ferric carboxymaltose using clinical trial reports and published reports. Methods Clinical trial reports were supplemented by electronic literature searches comparing ferric carboxymaltose with active comparators or placebo. Various outcomes were sought for efficacy (attainment of normal haemoglobin (Hb), increase of Hb by a defined amount, for example), together with measures of harm, including serious adverse events and deaths. Results Fourteen studies were identified with 2,348 randomised patients exposed to ferric carboxymaltose, 832 to oral iron, 762 to placebo, and 384 to intravenous iron sucrose. Additional data were available from cohort studies. Intravenous ferric carboxymaltose was given up to the calculated iron deficit (up to 1,000 mg in one week) for iron deficiency anaemia secondary to chronic kidney disease, blood loss in obstetric and gynaecological conditions, gastrointestinal disease, and other conditions like heart failure. The most common comparator was oral iron, and trials lasted 1 to 24 weeks. Intravenous ferric carboxymaltose improved mean Hb, serum ferritin, and transferrin saturation levels; the mean end-of-trial increase over oral iron was, for Hb 4.8 (95% confidence interval 3.3 to 6.3) g/L, for ferritin 163 (153 to 173) ?g/L, and for transferrin saturation 5.3% (3.7 to 6.8%). Ferric carboxymaltose was significantly better than comparator in achievement of target Hb increase (number needed to treat (NNT) 6.8; 5.3 to 9.7) and target Hb NNT (5.9; 4.7 to 8.1). Serious adverse events and deaths were similar in incidence in ferric carboxymaltose and comparators; rates of constipation, diarrhoea, and nausea or vomiting were lower than with oral iron. Conclusions This review examined the available trials of intravenous ferric carboxymaltose using details from published papers and unpublished clinical trial reports. It increases the evidence available to support recommendations given for intravenous iron treatment, but there are limited trial data comparing different intravenous iron preparations. PMID:21942989

  6. In Situ Iron Oxide Emplacement for Groundwater Arsenic Remediation

    E-print Network

    Abia, Thomas Sunday

    2012-02-14

    Microscopy Si Elemental silica SiO32- Silicate SO42- Sulfate STIOCS Iron Oxide-Coated Sand specific throughput t Adsorption time tage Ageing time tbreakthrough Breakthrough time tcoat Coating time WHO World Health Organization XRD X-ray Diffraction...+ (2) Equation 1 represents the formation of ferric oxide, e.g. hematite (?-Fe2O3), as the end product. In Equation 2, the oxidation of Fe2+ produces iron oxyhydroxide (e.g. lepidocrocite ?-FeOOH), which results from oxygen-induced oxidation followed...

  7. Occurrences at mineral-bacteria interface during oxidation of arsenopyrite by Thiobacillus ferrooxidans.

    PubMed

    Fernandez, M G; Mustin, C; de Donato, P; Barres, O; Marion, P; Berthelin, J

    1995-04-01

    The combination of an improved bacterial desorption method, scanning electron microscopy (SEM), diffuse reflectance and transmission infrared Fourier transform spectroscopy, and a desorption-leaching device like high-pressure liquid chromatography (HPLC) was used to analyze bacterial populations (adhering and free bacteria) and surface-oxidized phases (ferric arsenates and elemental sulfur) during the arsenopyrite biooxidation by Thiobacillus ferrooxidans. The bacterial distribution, the physicochemical composition of the leachate, the evolution of corrosion patterns, and the nature and amount of the surface-oxidized chemical species characterized different behavior for each step of arsenopyrite bioleaching. The first step is characterized by a slow but strong adhesion of bacteria to mineral surfaces, the appearance of a surface phase of elemental sulfur, the weak solubilization of Fe(II), As(III), and As(V), and the presence of the first corrosion patterns, which follow the fragility zones and the crystallographic orientation of mineral grains. After this short step, growth of the unattached bacteria begins, while ferrous ions in solution are oxidized by them. Ferric ions produced by the bacteria can oxidize the sulfide directly and are regenerated by Fe(II) bacterial oxidation. At this time, a bioleaching cycle takes place and a coarse surface phase of ferric arsenate (FeAsO(4) . xH(2)O where x approximately 2) and deep ovoid pores appear. At the end of the bioleaching cycle, the high concentration of Fe(III) and As(V) in solution promotes the precipitation of a second phase of amorphous ferric arsenate (FeAsO(4) . xH(2)O where x approximately 4) in the leachate. Then the biooxidation process ceases: The bacteria adhering to the mineral sufaces are coated by the ferric arsenates and the concentration of Fe(III) on the leachate is found to have decreased greatly. Both oxidation mechanisms (direct and indirect oxidation) have been stopped. (c) 1995 John Wiley & Sons, Inc. PMID:18623257

  8. The role of rare-earth dopants in nanophase zirconia catalysts for automotive emission control.

    SciTech Connect

    Loong, C.-K.; Ozawa, M.

    1999-07-16

    Rare earth (RE) modification of automotive catalysts (e.g., ZrO{sub 2}) for exhaust gas treatment results in outstanding improvement of the structural stability, catalytic functions and resistance to sintering at high temperatures. Owing to the low redox potential of nonstoichiometric CeO{sub 2}, oxygen release and intake associated with the conversion between the 3+ and 4+ oxidation states of the Ce ions in Ce-doped ZrO{sub 2} provide the oxygen storage capacity that is essentially to effective catalytic functions under dynamic air-to-fuel ratio cycling. Doping tripositive RE ions such as La and Nd in ZrO{sub 2}, on the other hand, introduces oxygen vacancies that affect the electronic and ionic conductivity. These effects, in conjunction with the nanostructure and surface reactivity of the fine powders, present a challenging problem in the development of better ZrO{sub 2}-containing three-way catalysts. We have carried out in-situ small-to-wide angle neutron diffraction at high temperatures and under controlled atmospheres to study the structural phase transitions, sintering behavior, and Ce{sup 3+} {leftrightarrow} Ce{sup 4+} redox process. We found substantial effects due to RE doping on the nature of aggregation of nanoparticles, defect formation, crystal phase transformation, and metal-support interaction in ZrO{sub 2} catalysts for automotive emission control.

  9. A functional nitric oxide reductase model

    PubMed Central

    Collman, James P.; Yang, Ying; Dey, Abhishek; Decréau, Richard A.; Ghosh, Somdatta; Ohta, Takehiro; Solomon, Edward I.

    2008-01-01

    A functional heme/nonheme nitric oxide reductase (NOR) model is presented. The fully reduced diiron compound reacts with two equivalents of NO leading to the formation of one equivalent of N2O and the bis-ferric product. NO binds to both heme Fe and nonheme Fe complexes forming individual ferrous nitrosyl species. The mixed-valence species with an oxidized heme and a reduced nonheme FeB does not show NO reduction activity. These results are consistent with a so-called “trans” mechanism for the reduction of NO by bacterial NOR. PMID:18838684

  10. Shallow-water hydrothermal system and sedimentation of the ferric deposit in the Nagahama-bay, Satsuma Iwo-jima Island

    NASA Astrophysics Data System (ADS)

    Ninomiya, T.; Kiyokawa, S.; Koge, S.; Oguri, K.; Yamaguchi, K. E.; Ito, T.; Ikehara, M.

    2008-12-01

    Satsuma Iwo-jima Island, located 40km south of Kyushu, Japan, has characteristic hydrothermal activities surrounding its active volcano Iwo-dake. Along the shoreline, hydrothermal fluids discharge and they cause discoloration of the seawater. At Nagahama-bay, iron ion in carbonated spring is oxidized to iron hydroxide precipitate by mixing with the sea water and the water takes on red color(Kamada, 1964). To understand the relationships among the ferric deposits, hydrothermal ventings, and the sea tide in the bay, we conducted the following studies; (a) naked eye observation at seafloor by SCUBA diving and the measurements of temperature and sediment distributions, (b) time-series in situ observation of the sesafloor by OGURI-View system (an automatic underwater digital camera system; Oguri et al., 2006), (c) time-series observation of color changes in the surface water by automatic acquisition system modified from OGURI-View, (d) geochemical analysis of the sea water collected in spring and fall 2007 and summer 2008, (e) coring to find the components in the sediment, and (f) six months-long sediment trap to estimate total mass flux in the bay. On the seafloor, numerous hot vents were found in the eastern part of the bay at 4m in depth. Soft sediment was also formed around the vents up to 1.5m thick. Temperature of the surface sediment ranged from 30 to 55 degree Celsius; the highest temperature was observed near those vents. The time-series images taken by OGURI-View system showed that turbidness of the bottom of the sea water changed daily. The turbidity data in the bay indicated that their daily changes occurred by tidal currents and sometimes by unusual mixing induced by strong typhoon. The sediment of 83cm core sample consisted of clay-sized reddish ferric oxides, quartz, volcanic ashes, rock fragments, and very fine to fine sand. From the sediment trap experiment, total mass accumulation rate was estimated to 0.12-0.18g/cm2/day. This high rate may be one factor contributing to the thick sediment.

  11. Ultrafiltration evaluation with depleted uranium oxide

    SciTech Connect

    Weisbrod, K.R.; Schake, A.R.; Morgan, A.N.; Purdy, G.M.; Martinez, H.E.; Nelson, T.O.

    1998-03-01

    Scientists at the Los Alamos National Laboratory Plutonium Facility are using electrodissolution in neutral to alkaline solutions to decontaminate oralloy parts that have surface plutonium contamination. Ultrafiltration of the electrolyte stream removes precipitate so that the electrolyte stream to the decontamination fixture is precipitate free. This report describes small-scale laboratory ultrafiltration experiments that the authors performed to determine conditions necessary for full-scale operation of an ultrafiltration module. Performance was similar to what they observed in the ferric hydroxide system. At 12 psi transmembrane pressure, a shear rate of 12,000 sec{sup {minus}1} was sufficient to sustain membrane permeability. Ultrafiltration of uranium(VI) oxide appears to occur as easily as ultrafiltration of ferric hydroxide. Considering the success reported in this study, the authors plan to add ultrafiltration to the next decontamination system for oralloy parts.

  12. Ferric sulfates on Mars: A combined mission data analysis of salty soils at Gusev crater and laboratory experimental investigations

    E-print Network

    ] Sulfate is one of the major types of secondary minerals found on Mars by recent missions, which reinforcesFerric sulfates on Mars: A combined mission data analysis of salty soils at Gusev crater with high degree of hydration during the moderate obliquity period on Mars. Additionally, the sulfates

  13. Bioavailability and the mechanisms of intestinal absorption of iron from ferrous ascorbate and ferric polymaltose in experimental animals

    Microsoft Academic Search

    G. Johnson; P. Jacobs

    1990-01-01

    The comparative bioavailability from matching quantities of iron in the form of ferrous ascorbate or ferric polymaltose was defined in rats. Studies were carried out in the intact animals under basal conditions and also when requirements for this metal were either increased or decreased by manipulating stores or erythropoietic activity. No significant difference was found in the total quantity of

  14. A systematic survey of antioxidant activity of 30 Chinese medicinal plants using the ferric reducing antioxidant power assay

    Microsoft Academic Search

    Chi-Chun Wong; Hua-Bin Li; Ka-Wing Cheng; Feng Chen

    2006-01-01

    The antioxidant activities and total phenolic contents of 30 Chinese medicinal plants were evaluated using the ferric reducing antioxidant power assay and the Folin–Ciocalteu method, respectively. The Chinese medicinal plants were extracted by the traditional method, boiling in water and also in 80% methanol. A significant and linear correlation coefficient between the antioxidant activity and the total phenolic content was

  15. Mineral leaching, iron precipitation, and the sulfate requirement for chemolithotrophic iron oxidation

    Microsoft Academic Search

    Norman Lazaroff

    1997-01-01

    The leaching of pyrite by Thiobacillus ferrooxidans results in formation of an aqueous Fe(III) sulfato complex that leaches pyrite and precipitates excess iron sulfate. However, until recently most general texts stated that the deposits formated by bacterial leaching of pyrite consited of ferric hydroxide, implying that the massive presence of sulfate played no role in the oxidation or precipitation of

  16. Authigenic vivianite in Potomac River sediments: control by ferric oxy-hydroxides.

    USGS Publications Warehouse

    Hearn, P.P.; Parkhurst, D.L.; Callender, E.

    1983-01-01

    Sand-size aggregates of vivianite crystals occur in the uppermost sediments of the Potomac River estuary immediately downstream from the outfall of a sewage treatment plant at the southernmost boundary of the District of Columbia, USA. They are most abundant in a small area of coarse sand (dredge spoil) which contrasts with the adjacent, much finer sediments. The sewage outfall supplies both reducing conditions and abundant phosphate. Analyses and calculations indicate that the pore waters in all the adjacent sediments are supersaturated with respect to vivianite. Its concentration in the coarse sand is attributed to the absence there of amorphous ferric oxyhydroxides, which are present in the finer sediments and preferentially absorb the phosphate ion. -H.R.B.

  17. Arsenic sorption onto titanium dioxide, granular ferric hydroxide and activated alumina: Batch and dynamic studies.

    PubMed

    Lescano, Maia R; Passalía, Claudio; Zalazar, Cristina S; Brandi, Rodolfo J

    2015-03-21

    The aim of this work was to evaluate and compare the efficiencies of three different adsorbents for arsenic (As) removal from water: titanium dioxide (TiO2), granular ferric hydroxide (GFH) and activated alumina (AA). Equilibrium experiments for dissolved arsenite and arsenate were carried out through batch tests. Freundlich and Langmuir isotherm models were adopted and their parameters were estimated by non-linear regressions. In addition, dynamic experiments were performed in mini fixed bed columns and breakthrough curves were obtained for each combination of sorbate/adsorbent. Experimental results obtained by column assays were compared with predictions of well-known breakthrough models (Bohart-Adams and Clark). Results indicate that As(V) is more easily adsorbed than As(III) for AA and GFH, while TiO2 has a similar behavior for both species. The titanium-based material is the most efficient adsorbent to carry out the process, followed by the GFH. PMID:25723069

  18. A high-throughput screening strategy for nitrile-hydrolyzing enzymes based on ferric hydroxamate spectrophotometry.

    PubMed

    He, Yu-Cai; Ma, Cui-Luan; Xu, Jian-He; Zhou, Li

    2011-02-01

    Nitrile-hydrolyzing enzymes (nitrilase or nitrile hydratase/amidase) have been widely used in the pharmaceutical industry for the production of carboxylic acids and their derivatives, and it is important to build a method for screening for nitrile-hydrolyzing enzymes. In this paper, a simple, rapid, and high-throughput screening method based on the ferric hydroxamate spectrophotometry has been proposed. To validate the accuracy of this screening strategy, the nitrilases from Rhodococcus erythropolis CGMCC 1.2362 and Alcaligenes sp. ECU0401 were used for evaluating the method. As a result, the accuracy for assaying aliphatic and aromatic carboxylic acids was as high as the HPLC-based method. Therefore, the method may be potentially used in the selection of microorganisms or engineered proteins with nitrile-hydrolyzing enzymes. PMID:21038095

  19. Treatment of antigen-induced arthritis in rabbits with dysprosium-165-ferric hydroxide macroaggregates

    SciTech Connect

    Zuckerman, J.D.; Sledge, C.B.; Shortkroff, S.; Venkatesan, P.

    1989-01-01

    Dysprosium-165-ferric hydroxide macroaggregates (/sup 165/Dy-FHMA) was used as an agent of radiation synovectomy in an antigen-induced arthritis model in New Zealand white rabbits. Animals were killed up to 6 months after treatment. /sup 165/Dy-FHMA was found to have a potent but temporary antiinflammatory effect on synovium for up to 3 months after treatment. Treated knees also showed significant preservation of articular cartilage architecture and proteoglycan content compared with untreated controls, but only during the first 3 months after treatment. In animals killed 3 and 6 months after treatment there were only minimal differences between the treated and untreated knees, indicating that the antiinflammatory effects on synovial tissue and articular cartilage preservation were not sustained.

  20. Molecular analysis of the fur (ferric uptake regulator) gene of a pathogenic Edwardsiella tarda strain.

    PubMed

    Wang, Fang; Cheng, Shuang; Sun, Kun; Sun, Li

    2008-06-01

    The gene encoding the Edwardsiella tarda ferric uptake regulator (Fur(Et)) was cloned from a pathogenic E. tarda strain isolated from diseased fish. Fur(Et) shares 90% overall sequence identity with the Escherichia coli Fur (Fur(Ec)) and was able to complement the mutant phenotype of a fur (Ec)-defective E. coli strain. Mutational analysis indicated that C92S and C95S mutations inactivated Fur(Et) whereas E112K mutation resulted in a superactive Fur(Et) variant. Fur(Et) negatively regulated its own expression; interruption of this regulation impaired bacterial growth, altered the production of certain outer membrane proteins, and attenuated bacterial virulence. PMID:18604507

  1. Capillary electrophoretic determination of ferric dimethyldithiocarbamate as iron(III) chelate of EDTA.

    PubMed

    Malik, A K; Seidel, B S; Faubel, W

    1999-10-01

    A simple and sensitive capillary electrophoretic method with UV detection has been developed for the determination of Ferbam (ferric dimethyldithiocarbamate) in boric acid buffer after its acidic decomposition and complexation with EDTA as Fe-EDTA- complex. The determination is dependent on the pH and the nature of the buffer solutions. In this method the detection limit (S/N = 3) is 1.8 x 10(-6) mol/L (0.7 mg/kg) of Ferbam. The relative standard deviation for the analysis of 50 microg/ml was found to be 2.9%. The method was successfully applied for the analysis of wheat grain samples spiked with Ferbam. The applicability of capillary electrophoresis as a useful tool for the analysis of Ferbam is demonstrated. PMID:10536858

  2. Ferric carboxymaltose: A revolution in the treatment of postpartum anemia in Indian women

    PubMed Central

    Rathod, Setu; Samal, Sunil K; Mahapatra, Purna C; Samal, Sunita

    2015-01-01

    Objectives: The objective of the present study is to compare the safety and efficacy of ferric carboxymaltose (FCM), intravenous (IV) iron sucrose and oral iron in the treatment of post = partum anemia (PPA). Materials and Methods: A total of 366 women admitted to SCB Medical College, Cuttack between September 2010 and August 2012 suffering from PPA hemoglobin (Hb) <10 g/dL were randomly assigned to receive either oral iron or IV FCM or iron sucrose. FCM, IV iron sucrose, and oral iron were given as per the protocol. Changes in hemoglobin (Hb) and serum ferritin levels at 2 and 6 weeks after treatment were measured and analyzed using ANOVA. Adverse effects to drug administration were also recorded. Results: A statistically significant increase in Hb and serum ferritin level were observed in all three groups, but the increase in FCM group was significantly higher (P < 0.0001) than conventional iron sucrose and oral iron group. The mean increase in Hb after 2 weeks was 0.8, 2.4, and 3.2 g/dL and 2.1, 3.4, and 4.4 g/dL at 6 weeks in oral iron, iron sucrose and FCM groups, respectively. The mean increase in serum ferritin levels after 2 weeks was 2.5, 193.1, and 307.1 and 14.2, 64, and 106.7 ng/mL after 6 weeks in oral iron, iron sucrose and FCM groups, respectively. Adverse drug reactions were significantly less (P < 0.001) in FCM group when compared with other two groups. Conclusion: Ferric carboxymaltose elevates Hb level and restores iron stores faster than IV iron sucrose and oral iron, without any severe adverse reactions. There was better overall satisfaction reported by the patients who received FCM treatment. PMID:25664264

  3. Concerted loop motion triggers induced fit of FepA to ferric enterobactin

    PubMed Central

    Smallwood, Chuck R.; Jordan, Lorne; Trinh, Vy; Schuerch, Daniel W.; Gala, Amparo; Hanson, Mathew; Shipelskiy, Yan; Majumdar, Aritri; Newton, Salete M.C.

    2014-01-01

    Spectroscopic analyses of fluorophore-labeled Escherichia coli FepA described dynamic actions of its surface loops during binding and transport of ferric enterobactin (FeEnt). When FeEnt bound to fluoresceinated FepA, in living cells or outer membrane fragments, quenching of fluorophore emissions reflected conformational motion of the external vestibular loops. We reacted Cys sulfhydryls in seven surface loops (L2, L3, L4, L5, L7 L8, and L11) with fluorophore maleimides. The target residues had different accessibilities, and the labeled loops themselves showed variable extents of quenching and rates of motion during ligand binding. The vestibular loops closed around FeEnt in about a second, in the order L3 > L11 > L7 > L2 > L5 > L8 > L4. This sequence suggested that the loops bind the metal complex like the fingers of two hands closing on an object, by individually adsorbing to the iron chelate. Fluorescence from L3 followed a biphasic exponential decay as FeEnt bound, but fluorescence from all the other loops followed single exponential decay processes. After binding, the restoration of fluorescence intensity (from any of the labeled loops) mirrored cellular uptake that depleted FeEnt from solution. Fluorescence microscopic images also showed FeEnt transport, and demonstrated that ferric siderophore uptake uniformly occurs throughout outer membrane, including at the poles of the cells, despite the fact that TonB, its inner membrane transport partner, was not detectable at the poles. PMID:24981231

  4. Control on size and adsorptive properties of spherical ferric phosphate particles.

    PubMed

    Kandori, Kazuhiko; Kuwae, Takanori; Ishikawa, Tatsuo

    2006-08-01

    Ferric phosphate particles were prepared by aging a solution dissolving Fe(ClO4)(3) and H3PO(4) at 40-80 degrees C for 16 h in a Teflon-lined screw-capped Pyrex test tube. The spherical or agglomerated fine particles were only precipitated with an extremely fast rate of reaction. The spherical particles were only produced at a very narrow region in fairly low pH solutions. TEM observation revealed that these particles grew in spherical structure by aggregation of primary small particles. The size of spherical particles was decreased by increase in the solute concentration or raising the aging temperature. Therefore, the formation of spherical particles was explained by a polynuclear layer mechanism proposed by Nielsen. The uniform spherical particles produced are amorphous, but they were crystallized to FePO(4) after calcining above 600 degrees C. It was suggested that the voids between the primary particles within the secondary agglomerated particles constitute mesopores. The Fe/P molar ratio determined and weight loss in TG curves gave the chemical formulas of the particles as Fe(PO4)x(H2PO4)y.nH2O (x: 0.93-1.00, y: 0-0.22, n: 2.4-2.7). The amorphous spherical ferric phosphate particles showed a high selective adsorption of H2O by penetration of H2O molecules into ultramicropores, produced after outgassing pretreatment, of that size is smaller than N2 molecule. The more particles grew, the more adsorption selectivity of H(2)O became remarkable. PMID:16677662

  5. Fabrication of novel chemosensors composed of rhodamine derivative for the detection of ferric ion and mechanism studies on the interaction between sensor and ferric ion.

    PubMed

    Shi, Dongjian; Ni, Ming; Luo, Jing; Akashi, Mitsuru; Liu, Xiaoya; Chen, Mingqing

    2015-02-21

    Although many rhodamine based fluorescence sensors were reported to detect metal ions with high sensitivity and selectivity, there are very few reports available to study the mechanisms of detection and the interaction between probe and metal ions. This paper aims to detect ferric ions by novel fluorescence chemosensors and study the mechanisms in detail. A novel probe AD-MAH-RhB was designed and synthesized from rhodamine B (RhB), adamantyl (AD), ethylene diamine and maleic anhydride (MAH). AD-MAH-RhB could detect Fe(3+) in aqueous solutions. The mechanism was explored by the HSAB principle, FTIR and mass spectra. The results suggested that Fe(3+) bound with amine and oxygen atoms in AD-MAH-RhB to form a complex composed of a 2?:?1 stoichiometry of Fe(3+) and the probe. Moreover, computational simulations were employed to further investigate the detection mechanism. The calculated results showed that Fe(3+) could conjugate with AD-MAH-RhB probe to form a stable complex, which was induced by synergetic effects of the suitable space and distance of van der Waals forces. However, Hg(2+) was found to disturb this detection and form a complex with 1?:?2 stoichiometry of Hg(2+) and AD-MAH-RhB. Then, another probe, ?-cyclodextrin modified polymaleic anhydride (PMAH-CD) including AD-MAH-RhB (PMAH-CD/AD-MAH-RhB) was fabricated by inclusion interaction between CD and AD. PMAH-CD@AD-MAH-RhB showed high selectivity and sensitivity to Fe(3+) in the aqueous solution by eliminating the interruption of Hg(2+) possibly due to the high hydrogen interaction among the probes to inhibit the stable form complex with Hg(2+). PMID:25574522

  6. Polybenzimidazole block copolymers for fuel cell: synthesis and studies of block length effects on nanophase separation, mechanical properties, and proton conductivity of PEM.

    PubMed

    Maity, Sudhangshu; Jana, Tushar

    2014-05-14

    A series of meta-polybenzimidazole-block-para-polybenzimidazole (m-PBI-b-p-PBI), segmented block copolymers of PBI, were synthesized with various structural motifs and block lengths by condensing the diamine terminated meta-PBI (m-PBI-Am) and acid terminated para-PBI (p-PBI-Ac) oligomers. NMR studies and existence of two distinct glass transition temperatures (Tg), obtained from dynamical mechanical analysis (DMA) results, unequivocally confirmed the formation of block copolymer structure through the current polymerization methodology. Appropriate and careful selection of oligomers chain length enabled us to tailor the block length of block copolymers and also to make varieties of structural motifs. Increasingly distinct Tg peaks with higher block length of segmented block structure attributed the decrease in phase mixing between the meta-PBI and para-PBI blocks, which in turn resulted into nanophase segregated domains. The proton conductivities of proton exchange membrane (PEM) developed from phosphoric acid (PA) doped block copolymer membranes were found to be increasing substantially with increasing block length of copolymers even though PA loading of these membranes did not alter appreciably with varying block length. For example when molecular weight (Mn) of blocks were increased from 1000 to 5500 then the proton conductivities at 160 °C of resulting copolymers increased from 0.05 to 0.11 S/cm. Higher block length induced nanophase separation between the blocks by creating less morphological barrier within the block which facilitated the movement of the proton in the block and hence resulting higher proton conductivity of the PEM. The structural varieties also influenced the phase separation and proton conductivity. In comparison to meta-para random copolymers reported earlier, the current meta-para segmented block copolymers were found to be more suitable for PBI-based PEM. PMID:24712484

  7. Removal of Selenium from Wastewater using ZVI and Hybrid ZVI/Iron Oxide Process

    E-print Network

    Yang, Zhen

    2012-12-20

    as well such as peat impregnated with ferric oxyhydroxide (Chamberlin, 1996). In studies by USBM (Corwin et al., 1994; Jeffers et al., 1991), ferric oxyhydroxide and peat were mixed into beads of polysulfone resin and the resin with Se of 1700 mg...% of the SeCN- at bench scale. Further study may including but not limited to: 1)Experiments withXRD and SEM analyses to further understand the CORROSION and layer formation of iron oxide on the surface of ZVI and the oxidise of SeCN- and adsorption...

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

    NASA Astrophysics Data System (ADS)

    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 nanohematite is the dominant ferric oxide in most dust-on-snow (DOS) samples (collected 2005-2010) from the San Juan Mountains and in many redbed-derived dust sources upwind in Colorado Plateau drylands. Goethite in some San Juan Mountain DOS is probably derived from source-area sediments from Cretaceous marine deposits. In contrast, goethite appears to be the dominant ferric oxide in Wasatch Mountains DOS collected in 2010. Goethite-bearing Late Pleistocene lake sediments in west-central Utah have been identified as the dominant dust sources for these DOS layers from satellite retrievals. The distinction between hematite and goethite is useful for modeling radiative forcing by dust in mountain snow and ice and in the atmosphere.

  9. Microbiological oxidation of synthetic chalcocite and covellite by Thiobacillus ferrooxidans.

    PubMed Central

    Sakaguchi, H; Torma, A E; Silver, M

    1976-01-01

    The microbiological oxidation of synthetic chalcocite and covellite has been investigated using an adapted strain of Thiobacillus ferrooxidans. Biodegradation of chalcocite was found to be 90 to 100% and that of covellite 45 to 60%. Optimum conditions for the oxidation of chalcocite were: pH, 1.7 to 2.3; temperature, 35 C; and ferric iron concentration in the range of 0.004 to 0.01 M. For covellite, the optimum conditions were: pH 2.3; temperature, 35 C; and ferric iron concentration in the range of 0.004 to 0.02 M. The energies of activation were determined to be 16.3 kcal (ca. 6.8 X 10(4) J) per mol and 11.7 kcal (ca. 4.8 X 10(4) J) per mol for chalcocite and covellite, respectively. PMID:8006

  10. Five- and Six-Coordinate Adducts of Nitrosamines with Ferric Porphyrins: Structural Models for the Type II Interactions of Nitrosamines with Ferric Cytochrome P450

    PubMed Central

    Xu, Nan; Goodrich, Lauren E.; Powell, Douglas R.

    2010-01-01

    Nitrosamines are well known for their toxic and carcinogenic properties. The metabolic activation of nitrosamines occur via interaction with the heme-containing cytochrome P450 enzymes. We report the preparation and structural characterization of a number of nitrosamine adducts of synthetic iron porphyrins. The reactions of the cations [(por)Fe(THF)2]ClO4 (por = TPP, TTP, OEP) with dialkylnitrosamines (R2NNO; R2 = Me2, Et2, (cyclo-CH2)4, (cyclo-CH2)5, (PhCH2)2) in toluene generate the six-coordinate high-spin (S = 5/2) [(por)Fe(ONNR2)2]ClO4 compounds and a five-coordinate intermediate-spin (S = 3/2) [(OEP)Fe(ONNMe2)]ClO4 derivative in 57–72% yields (TPP = 5,10,15,20-tetraphenylporphyrinato dianion, TTP = 5,10,15,20-tetra-p-tolylporphyrinato dianion, OEP = 2,3,7,8,12,13,17,18-octaethylporphyrinato dianion). The N–O and N–N vibrations of the coordinated nitrosamine groups in [(por)Fe(ONNR2)2]ClO4 occur in the 1238–1285 cm?1 range. Three of the six-coordinate [(por)Fe(ONNR2)2]ClO4 compounds and one five-coordinate [(OEP)Fe(ONNMe2)]ClO4 compound have been characterized by single crystal X-ray crystallography. All the nitrosamine ligands in these complexes bind to the ferric centers via a sole ?1-O binding mode. No arylnitrosamine adducts were obtained from the reactions of the precursor compounds [(por)Fe(THF)2]ClO4 with three arylnitrosamines (Ph2NNO, Ph(Me)NNO, Ph(Et)NNO). However, prolonged exposure of [(por)Fe(THF)2]ClO4 to these arylnitrosamines resulted in the formation of the known five-coordinate (por)Fe(NO) derivatives. The latter (por)Fe(NO) compounds were obtained more readily by the reactions of the three arylnitrosamines with the four-coordinate (por)FeII precursors. PMID:20392126

  11. Kinetic and spectroscopic studies of N694C lipoxygenase: a probe of the substrate activation mechanism of a nonheme ferric enzyme.

    PubMed

    Neidig, Michael L; Wecksler, Aaron T; Schenk, Gerhard; Holman, Theodore R; Solomon, Edward I

    2007-06-20

    Lipoxygenases (LOs) comprise a class of substrate activating mononuclear nonheme iron enzymes which catalyze the hydroperoxidation of unsaturated fatty acids. A commonly proposed mechanism for LO catalysis involves H-atom abstraction by an FeIII-OH- site, best described as a proton coupled electron transfer (PCET) process, followed by direct reaction of O2 with the resulting substrate radical to yield product. An alternative mechanism that has also been discussed involves the abstraction of a proton from the substrate by the FeIII-OH leading to a sigma-organoiron intermediate, where the subsequent sigma bond insertion of dioxygen into the C-Fe bond completes the reaction. H-atom abstraction is favored by a high E(o) of the FeII/FeIII couple and high pK(a) of water bound to the ferrous state, while an organoiron mechanism would be favored by a low E(o) (to keep the site oxidized) and a high pK(a) of water bound to the ferric state (to deprotonate the substrate). A first coordination sphere mutant of soybean LO (N694C) has been prepared and characterized by near-infrared circular dichroism (CD) and variable-temperature, variable-field (VTVH) magnetic circular dichroism (MCD) spectroscopies (FeII site), as well as UV/vis absorption, UV/vis CD, and electron paramagnetic resonance (EPR) spectroscopies (FeIII site). These studies suggest that N694C has a lowered E degrees of the FeII/FeIII couple and a raised pKa of water bound to the ferric site relative to wild type soybean lipoxygenase-1 (WT sLO-1) which would favor the organoiron mechanism. However, the observation in N694C of a significant deuterium isotope effect, anaerobic reduction of iron by substrate, and a substantial decrease in k(cat) (approximately 3000-fold) support H-atom abstraction as the relevant substrate-activation mechanism in sLO-1. PMID:17523638

  12. Comparative stability of the bioresorbable ferric crosslinked hyaluronic acid adhesion prevention solutions.

    PubMed

    Luu, Hoan-My Do; Chen, Angela; Isayeva, Irada S

    2013-08-01

    The Intergel® ferric crosslinked hyaluronate (FeHA) adhesion prevention solution (APS) (FDA) is associated with serious post-operative complications (Henley, http://www.lawyersandsettlements.com/features/gynecare-intergel/intergel-timeline.html, 2007; FDA, 2003; Roman et al., Fertil Steril 2005, 83 Suppl 1:1113-1118; Tang et al., Ann Surg 2006;243(4):449-455; Wiseman, Fertil Steril 2006;86(3):771; Wiseman, Fertil Steril 2006;85(4):e7). This prompted us to examine the in situ stability of crosslinked HA materials to hyaluronidase lyase degradation. Variables such as ferric ionic crosslink density, HA concentration, gel geometry, and molecular weight (MW) of HA polymer were studied. Various formulations of the crosslinked "in house" [Isayeva et al., J Biomed Mater Res: Part B - Appl Biomater 2010, 95B (1):9-18] FeHA (0.5%, w/v; 30, 50, 90% crosslinked), the Intergel® FeHA (0.5%, w/v; 90%), and the non-crosslinked HA (0.05-0.5%, w/v) were degraded at a fixed activity of hyaluronidase lyase from Streptomyces hyalurolyticus (Hyase) at 37°C over time according to the method [Payan et al., J Chrom B: Biomed Sci Appl 1991;566(1):9-18]. Under our conditions, the data show that the crosslink density affects degradation the most, followed by HA concentration and then gel geometry. We found that MW has no effect. Our results are one possible explanation of the observations that the Intergel® FeHA APS (0.5%, w/v; 90%) material persisted an order of magnitude longer than expected [t1/2 = 500 hrs vs. t1/2 = 50 hrs (FDA; Johns et al., Fertil Steril 1997;68(1):37-42)]. These data also demonstrate the sensitivity of the in vitro hyaluronidase assay to predict the in situ stability of crosslinked HA medical products as previously reported [Sall et al., Polym Degrad Stabil 2007;92(5):915-919]. PMID:23559362

  13. Effects of fasting and/or oxidizing and reducing agents on absorption of neptunium from the gastrointestinal tract of mice and adult or neonatal rats.

    PubMed

    Sullivan, M F; Ruemmler, P S; Ryan, J L

    1984-12-01

    Neptunium-237(V) nitrate was administered by gavage to groups of fed or fasted adult and 5-day-old rats. Some groups also received the oxidants quinhydrone or ferric iron, and others received the reducing agent ferrous iron. Adult mice received ferric or ferrous iron and 235Np. When the adult rats were killed at 7 days after gavage, measurements showed that, compared with rats that were fed, a 24-hr fast caused a fivefold increase in 237Np absorption and retention. Both quinhydrone and ferric iron caused an even greater increase in absorption in both fed and fasted rats. Ferrous iron, on the other hand, decreased absorption in fasted rats to values lower than those obtained in fed rats. Similar results were obtained in mice treated with 235Np and either ferric or ferrous iron. The highest absorption obtained after gavage of ferric iron to fasted rats and mice was about two orders of magnitude higher than the value obtained in animals that were fed before gavage. The effects of ferric and ferrous iron on neptunium absorption by neonatal rats were similar to their effects on adult animals but of lesser magnitude. These results are consistent with the hypothesis that Np(V), when given in small mass quantities to fed animals, is reduced in the gastrointestinal tract to Np(IV), which is less well absorbed than Np(V). PMID:6505141

  14. The Enzyme-mimic Activity of Ferric Nano-Core Residing in Ferritin and Its Biosensing Applications

    SciTech Connect

    Tang, Zhiwen; Wu, Hong J.; Zhang, Youyu; Li, Zhaohui; Lin, Yuehe

    2011-11-15

    Ferritins are nano-scale globular protein cages encapsulating a ferric core. They widely exist in animals, plants, and microbes, playing indispensable roles in iron homeostasis. Interestingly, our study clearly demonstrates that ferritin has an enzyme-mimic activity derived from its ferric nano-core, but not the protein cage. Further study revealed that the mimic-enzyme activity of ferritin is more thermally stable and pH-tolerant compared with horseradish peroxidase. Considering the abundance of ferritin in numerous organisms, this finding may indicate a new role of ferritin in antioxidant and detoxification metabolisms. In addition, as a natural protein-caged nanoparticle with an enzyme-mimic activity, ferritin is readily conjugated with biomolecules to construct nano-biosensors, thus holds promising potential for facile and biocompatible labeling for sensitive and robust bioassays in biomedical applications.

  15. Conversion of dissolved phosphorus in runoff by ferric sulfate to a form less available to algae: Field performance and cost assessment.

    PubMed

    Uusitalo, Risto; Närvänen, Aaro; Kaseva, Antti; Launto-Tiuttu, Aino; Heikkinen, Janne; Joki-Heiskala, Päivi; Rasa, Kimmo; Salo, Tapio

    2015-03-01

    Conversion of dissolved P by ferric sulfate into a particulate form sparingly available to algae was studied in 15 ditches in Finland using stand-alone dispensers for ferric sulfate administration. Ferric sulfate typically converted 60-70 % of dissolved P into iron-associated form, a process which required 250-650 kg per kg dissolved P. Mean cost was 160 EUR per kg P converted (range 20-400 EUR kg(-1)). The costs were lowest at sites characterized by high dissolved P concentrations and small catchment area. At best, the treatment was efficient and cost-effective, but to limit the costs and the risks, ferric sulfate dispensers should only be installed in small critical source areas. PMID:25681985

  16. Novel Role of the Lipopolysaccharide O1 Side Chain in Ferric Siderophore Transport and Virulence of Vibrio anguillarum

    Microsoft Academic Search

    Timothy J. Welch; Jorge H. Crosa

    2005-01-01

    From a library of approximately 20,000 transposon mutants, we have identified mutants affected in chro- mosomal genes involved in synthesis of the siderophore anguibactin, as well as in ferric anguibactin utilization. Genetic and sequence analyses of one such transport-defective mutant revealed that the transposon insertion occurred in an open reading frame (ORF) with homology to rmlC, a dTDP-rhamnose biosynthetic gene.

  17. Occurrence and regulation of the ferric citrate transport system in Escherichia coli B, Klebsiella pneumoniae, Enterobacter aerogenes, and Photorhabdus luminescens

    Microsoft Academic Search

    Susanne Mahren; Heidrun Schnell; Volkmar Braun

    2005-01-01

    In Escherichia coli K-12, transcription of the ferric citrate transport genes fecABCDE is initiated by binding of diferric dicitrate to the outer membrane protein FecA which elicits a signaling cascade from the\\u000a cell surface to the cytoplasm. The FecI sigma factor is only active in the presence of FecR, which transfers the signal across\\u000a the cytoplasmic membrane. In other bacteria,

  18. Absorption of dilute SO 2 gas stream with conversion to polymeric ferric sulfate for use in water treatment

    Microsoft Academic Search

    Aron D Butler; Maohong Fan; Robert C Brown; Adrienne T Cooper; J. H van Leeuwen; Shihwu Sung

    2004-01-01

    Use of sulfur dioxide (SO2) in the production of polymeric ferric sulfate (PFS) was investigated. PFS is a highly effective coagulant useful in treatment of drinking water and wastewater, and could serve as a value-added sink for sulfur removed during coal gas cleanup. SO2 was absorbed from a dilute gas stream by sparging it into a bench-scale reactor containing a

  19. Selective detection of ferric ions by blue-green photoluminescent nitrogen-doped phenol formaldehyde resin polymer.

    PubMed

    Zhang, Jia; Yuan, Yue; Yu, Zhi-Long; Yu, Aimin; Yu, Shu-Hong

    2014-09-24

    The smaller, the more fluorescent: The hydrothermal reaction of phenol with hexamethylenetetramine (HMT) leads to two morphologies of phenol formaldehyde resin (PFR), namely, bigger nanoparticles with feeble green fluorescence and smaller amorphous polymers with strong blue-green fluorescence. It reveals that both of them are doped with nitrogen, and the blue-green photoluminescent polymer is confirmed to sense ferric ion (Fe(3+) ) with high selectivity. PMID:24863556

  20. Leaching of Arsenic from Granular Ferric Hydroxide Residuals under Mature Landfill Conditions

    PubMed Central

    Ghosh, Amlan; Mukiibi, Muhammed; Sáez, A. Eduardo; Ela, Wendell P.

    2008-01-01

    Most arsenic bearing solid residuals (ABSR) from water treatment will be disposed in non-hazardous landfills. The lack of an appropriate leaching test to predict arsenic mobilization from ABSR creates a need to evaluate the magnitude and mechanisms of arsenic release under landfill conditions. This work studies the leaching of arsenic and iron from a common ABSR, granular ferric hydroxide, in a laboratory-scale column that simulates the biological and physicochemical conditions of a mature, mixed solid waste landfill. The column operated for approximately 900 days and the mode of transport as well as chemical speciation of iron and arsenic changed with column age. Both iron and arsenic were readily mobilized under the anaerobic, reducing conditions. During the early stages of operation, most arsenic and iron leaching (80% and 65%, respectively) was associated with suspended particulate matter and iron was lost proportionately faster than arsenic. In later stages, while the rate of iron leaching declined, the arsenic leaching rate increased greater than 7-fold. The final phase was characterized by dissolved species leaching. Future work on the development of standard batch leaching tests should take into account the dominant mobilization mechanisms identified in this work: solid associated transport, reductive sorbent dissolution, and microbially mediated arsenic reduction. PMID:17051802

  1. Overproduction in Escherichia coli and Characterization of a Soybean Ferric Leghemoglobin Reductase.

    PubMed Central

    Ji, L.; Becana, M.; Sarath, G.; Shearman, L.; Klucas, R. V.

    1994-01-01

    We previously cloned and sequenced a cDNA encoding soybean ferric leghemoglobin reductase (FLbR), an enzyme postulated to play an important role in maintaining leghemoglobin in a functional ferrous state in nitrogen-fixing root nodules. This cDNA was sub-cloned into an expression plasmid, pTrcHis C, and overexpressed in Escherichia coli. The recombinant FLbR protein, which was purified by two steps of column chromatography, was catalytically active and fully functional. The recombinant FLbR cross-reacted with antisera raised against native FLbR purified from soybean root nodules. The recombinant FLbR, the native FLbR purified from soybean (Glycine max L.) root nodules, and dihydrolipoamide dehydrogenases from pig heart and yeast had similar but not identical ultraviolet-visible absorption and fluorescence spectra, cofactor binding, and kinetic properties. FLbR shared common structural features in the active site and prosthetic group binding sites with other pyridine nucleotide-disulfide oxidoreductases such as dihydrolipoamide dehydrogenases, but displayed different microenvironments for the prosthetic groups. PMID:12232320

  2. Passive immunization by recombinant ferric enterobactin protein (FepA) from Escherichia coli O157

    PubMed Central

    Larrie-Bagha, Seyed Mehdi; Rasooli, Iraj; Mousavi-Gargari, Seyed Latif; Rasooli, Zohreh; Nazarian, Shahram

    2013-01-01

    Background and Objectives Enterohemorrhagic Escherichia coli (EHEC) O157:H7 has been recognized as a major food borne pathogen responsible for frequent hemorrhagic colitis and hemolytic uremic syndrome in humans. Cattle are important reservoirs of E. coli O157:H7, in which the organism colonizes the intestinal tract and is shed in the feces. Objective Vaccination of cattle has significant potential as a pre-harvest intervention strategy for E. coli O157:H7. The aim of this study was to evaluate active and passive immunization against E. coli O157:H7 using a recombinant protein. Materials and Methods The recombinant FepA protein induced by IPTG was purified by nickel affinity chromatography. Antibody titre was determined by ELISA in FepA immunized rabbits sera. Sera collected from vaccinated animals were used for bacterial challenge in passive immunization studies. Results The results demonstrate that passive immunization with serum raised against FepA protects rabbits from subsequent infection. Conclusion Significant recognition by the antibody of ferric enterobactin binding protein may lead to its application in the restriction of Enterobacteriaceae propagation. PMID:23825727

  3. NMR reveals pathway for ferric mineral precursors to the central cavity of ferritin

    PubMed Central

    Turano, Paola; Lalli, Daniela; Felli, Isabella C.; Theil, Elizabeth C.; Bertini, Ivano

    2010-01-01

    Ferritin is a multimeric nanocage protein that directs the reversible biomineralization of iron. At the catalytic ferroxidase site two iron(II) ions react with dioxygen to form diferric species. In order to study the pathway of iron(III) from the ferroxidase site to the central cavity a new NMR strategy was developed to manage the investigation of a system composed of 24 monomers of 20 kDa each. The strategy is based on 13C-13C solution NOESY experiments combined with solid-state proton-driven 13C-13C spin diffusion and 3D coherence transfer experiments. In this way, 75% of amino acids were recognized and 35% sequence-specific assigned. Paramagnetic broadening, induced by iron(III) species in solution 13C-13C NOESY spectra, localized the iron within each subunit and traced the progression to the central cavity. Eight iron ions fill the 20-?-long iron channel from the ferrous/dioxygen oxidoreductase site to the exit into the cavity, inside the four-helix bundle of each subunit, contrasting with short paths in models. Magnetic susceptibility data support the formation of ferric multimers in the iron channels. Multiple iron channel exits are near enough to facilitate high concentration of iron that can mineralize in the ferritin cavity, illustrating advantages of the multisubunit cage structure. PMID:20018746

  4. Resonance Raman study of ferric heme adducts of dehaloperoxidase from Amphitrite ornata.

    PubMed

    Belyea, Jennifer; Belyea, Curtis M; Lappi, Simon; Franzen, Stefan

    2006-12-01

    The study of axial ligation by anionic ligands to ferric heme iron by resonance Raman spectroscopy provides a basis for comparison of the intrinsic electron donor ability of the proximal histidine in horse heart myoglobin (HHMb), dehaloperoxidase (DHP), and horseradish peroxidase (HRP). DHP is a dimeric hemoglobin (Hb) originally isolated from the terebellid polychaete Amphitrite ornata. The monomers are structurally related to Mb and yet DHP has a peroxidase function. The core size marker modes, v2 and v3, were observed using Soret excitation, and DHP-X was compared to HHMb-X for the ligand series X = F, Cl, Br, SCN, OH, N3, and CN. Special attention was paid to the hydroxide adduct, which is also formed during the catalytic cycle of peroxidases. The Fe-OH stretching frequency was observed and confirmed by deuteration and is higher in DHP than in HHMb. The population of high-spin states of the heme iron in DHP was determined to be intermediate between HHMb and HRP. The data provide the first direct measurement of the effect of axial ligation on the heme iron in DHP. The Raman data support a modified charge relay in DHP, in which a strongly hydrogen-bonded backbone carbonyl (>C=O) polarizes the proximal histidine. The charge relay mechanism by backbone carbonyl >C=O-His-Fe is the analogue of the Asp-His-Fe of peroxidases and Glu-His-Fe of flavohemoglobins. PMID:17128967

  5. Investigations of the low frequency modes of ferric cytochrome c using vibrational coherence spectroscopy.

    PubMed

    Karunakaran, Venugopal; Sun, Yuhan; Benabbas, Abdelkrim; Champion, Paul M

    2014-06-12

    Femtosecond vibrational coherence spectroscopy is used to investigate the low frequency vibrational dynamics of the electron transfer heme protein, cytochrome c (cyt c). The vibrational coherence spectra of ferric cyt c have been measured as a function of excitation wavelength within the Soret band. Vibrational coherence spectra obtained with excitation between 412 and 421 nm display a strong mode at ~44 cm(-1) that has been assigned to have a significant contribution from heme ruffling motion in the electronic ground state. This assignment is based partially on the presence of a large heme ruffling distortion in the normal coordinate structural decomposition (NSD) analysis of the X-ray crystal structures. When the excitation wavelength is moved into the ~421-435 nm region, the transient absorption increases along with the relative intensity of two modes near ~55 and 30 cm(-1). The intensity of the mode near 44 cm(-1) appears to minimize in this region and then recover (but with an opposite phase compared to the blue excitation) when the laser is tuned to 443 nm. These observations are consistent with the superposition of both ground and excited state coherence in the 421-435 nm region due to the excitation of a weak porphyrin-to-iron charge transfer (CT) state, which has a lifetime long enough to observe vibrational coherence. The mode near 55 cm(-1) is suggested to arise from ruffling in a transient CT state that has a less ruffled heme due to its iron d(6) configuration. PMID:24823442

  6. Evaluation of formocresol, calcium hydroxide, ferric sulfate, and MTA primary molar pulpotomies

    PubMed Central

    Yildiz, Esma; Tosun, Gul

    2014-01-01

    Objective: The aim of this study is to evaluate four different pulpotomy medicaments in primary molars. Materials and Methods: A total of 147 primary molars with deep caries were treated with four different pulpotomy medicaments (FC: formocresol, FS: ferric sulfate, CH: calcium hydroxide, and MTA: mineral trioxide aggregate) in this study. The criteria for tooth selection for inclusion were no clinical and radiographic evidence of pulp pathology. During 30 months of follow-up at 6-month intervals, clinical and radiographic success and failures were recorded. The differences between the groups were statistically analyzed using the Chi-square test and Kaplan-Meier analysis. Results: At 30 months, clinical success rates were 100%, 95.2%, 96.4%, and 85% in the FC, FS, MTA, and CH groups, respectively. In radiographic analysis, the MTA group had the highest (96.4%), and the CH group had the lowest success rate (85%). There were no clinical and radiographic differences between materials (P > 0.05). Conclusions: Although there were no differences between materials, only in the CH group did three teeth require extraction due to further clinical symptoms of radiographic failures during the 30-month follow-up period. None of the failed teeth in the other groups required extraction during the 30-month follow-up period. PMID:24966776

  7. Time-dependence of ferric reducing antioxidant power (FRAP) index in Chilean apples and berries.

    PubMed

    Henríquez, Carolina; López-Alarcón, Camilo; Gómez, Maritza; Lutz, Mariane; Speisky, Hernán

    2011-09-01

    We hypothesize that the Ferric Reducing Antioxidant Power (FRAP) assay that follows the reaction of Fe(3+)-TPTZ at 593 nm underestimates the antioxidant capacity of fruits, since the standardized time of the reaction (4 min) is not enough to titrate all the reducing compounds available. We measured FRAP, total phenolics and anthocyanins content in a variety of Chilean berry fruits (blueberries, blackberries, raspberries and strawberries) and apples (cv. Fuji, Granny Smith, Pink Lady, Red Delicious and Royal Gala). Taking into account the dependence of FRAP on the time course of the reaction, we propose to measure FRAP indexes after 1 min (FRAP-1), 30 min (FRAP-30) and 120 min (FRAP-120) of incubation. Most fruit extracts showed significant correlations between the antioxidant capacity and the incubation time, although in some cases the FRAP indexes did not correlate with the total phenolics and/or anthocyanins content. In fact, in apples and berries the correlation between anthocyanins content and FRAP indexes decreased with the incubation time. It is concluded that the fruit extracts analyzed require an incubation period higher than the established in the original experimental protocol to reach the equilibrium, due to the presence of a complex mixture of antioxidant compounds. In addition, a kinetic profile should be realized in each sample studied to establish the most suitable incubation period to titrate all the reactive antioxidant species. PMID:22696902

  8. Antioxidant property of volatile oils determined by the ferric reducing ability.

    PubMed

    Lado, Cristina; Then, Mária; Varga, Ilona; Szoke, Eva; Szentmihályi, Klára

    2004-01-01

    Some current oils and their main components were studied to determine their antioxidant values. This was done by using the modified method of ferric reducing ability of plasma. It has been established that volatile oils of medicinal plants have on average a reducing capacity of 3.5-220 mmol/kg oil. The reducing capacities of the main constituents of volatile oils are 0.165-65.5 mmol/kg in concentrated oils. The highest reducing capacity was showd for phellandrene (65.438 +/- 0.166 mmol/kg) and anethole (50.087 +/- 0.160 mmol/kg) while the lowest values were obtained for menthol (0.165 +/- 0.023 mmol/kg) and menthone (0.168 +/- 0.010 mmol/kg). It has been stated that the antioxidant values of the main constituents are lower than those of volatile oils. The reducing capacity of the main constituents of medicinal plant drugs at different concentrations was also determined. PMID:18998400

  9. Stage-1 intercalation compounds of few graphene layers by anhydrous ferric chloride

    NASA Astrophysics Data System (ADS)

    Tan, Pingheng; Zhao, Weijie; Liu, Jian; Ferrari, Andrea

    2012-02-01

    Anhydrous ferric chloride (FeCl3) was used to intercalate few graphene layers into stage-1 intercalation compounds. The intercalant, staging, stability, and doping of the resulting intercalation compounds are characterized by Raman scattering. The G peak of pure stage-1 compounds upshifts to ˜1626 cm-1, which is similar to that of heavily-doped monolayer graphenes by 18M sulfuric acid. A single Lorentzian line shape for the 2D band of stage-1 compounds were observed, which indicates that each layer behaves as a decoupled heavily doped monolayer. By performing Raman measurements at different excitation energies, we show that, for a given doping level, the variation of the 2D intensity relative to the G peak with excitation energy allows one to assess the Fermi energy. This allows us to estimate a Fermi level shift of up to ˜0.85 eV, which agrees well with that estimated from the 2D/G intensity ratio and is close to ˜0.9 eV measured in stage-1 GICs by electron energy loss spectroscopy. The stage-1 intercalation compound of few graphene layers is thus ideal test-beds for the physical and chemical properties of heavily doped graphenes.

  10. Spectrophotometric techniques to determine tranexamic acid: Kinetic studies using ninhydrin and direct measuring using ferric chloride

    NASA Astrophysics Data System (ADS)

    Arayne, M. Saeed; Sultana, Najma; Siddiqui, Farhan Ahmed; Mirza, Agha Zeeshan; Zuberi, M. Hashim

    2008-11-01

    Two simple and sensitive spectrophotometric methods in ultraviolet and visible region are described for the determination of tranexamic acid in pure form and pharmaceutical preparations. The first method is based on the reaction of the drug with ninhydrin at boiling temperature and by measuring the increase in absorbance at 575 nm as a function of time. The initial rate, rate constant and fixed time (120 min) procedures were used for constructing the calibration graphs to determine the concentration of the drug, which showed a linear response over the concentration range 16-37 ?g mL -1 with correlation coefficient " r" 0.9997, 0.996, 0.9999, LOQ 6.968, 7.138, 2.462 ?gmL -1 and LOD 2.090, 2.141 and 0.739 ?gmL -1, respectively. In second method tranexamic acid was reacted with ferric chloride solution, yellowish orange colored chromogen showed ? max at 375 nm showing linearity in the concentration range of 50-800 ?g mL -1 with correlation coefficient " r" 0.9997, LOQ 6.227 ?gmL -1 and LOD 1.868 ?gmL -1. The variables affecting the development of the color were optimized and the developed methods were validated statistically and through recovery studies. These results were also verified by IR and NMR spectroscopy. The proposed methods have been successfully applied to the determination of tranexamic acid in commercial pharmaceutical formulation.

  11. Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor.

    PubMed

    Feng, Jie; Ju, Yuyun; Liu, Juanjuan; Zhang, Huige; Chen, Xingguo

    2015-01-01

    In this report we reported a facile one-pot method for synthesis of water-soluble and stable fluorescent CuNCs at room temperature, in which branched polyethyleneimine (BPEI) served as capping scaffold and ascorbic acid as reducing agent. The prepared BPEI-CuNCs exhibited excellent properties such as good water-solubility, photostability and high stability toward high ionic strength. Based on the electron transfer induced fluorescence quenching mechanism, this fluorescence probe was used for the sensitive and selective determination of ferric ions (Fe(3+)) in aqueous solution. The limit of detection was 340 nM in the linear range of 0.5-1000 ?M, which was lower than the maximum level of Fe(3+) permitted in drinking water by the U.S. Environmental Protection Agency. The method was successfully applied to the detection of Fe(3+) in tap water, Yellow River water and human urine samples with the quantitative spike recoveries ranging from 95.3% to 112.0%. PMID:25479879

  12. The Regulatory Role of Ferric Uptake Regulator (Fur) during Anaerobic Respiration of Shewanella piezotolerans WP3

    PubMed Central

    Yang, Xin-Wei; He, Ying; Xu, Jun; Xiao, Xiang; Wang, Feng-Ping

    2013-01-01

    Ferric uptake regulator (Fur) is a global regulator that controls bacterial iron homeostasis. In this study, a fur deletion mutant of the deep-sea bacterium Shewanella piezotolerans WP3 was constructed. Physiological studies revealed that the growth rate of this mutant under aerobic conditions was only slightly lower than that of wild type (WT), but severe growth defects were observed under anaerobic conditions when different electron acceptors (EAs) were provided. Comparative transcriptomic analysis demonstrated that Fur is involved not only in classical iron homeostasis but also in anaerobic respiration. Fur exerted pleiotropic effects on the regulation of anaerobic respiration by controlling anaerobic electron transport, the heme biosynthesis system, and the cytochrome c maturation system. Biochemical assays demonstrated that levels of c-type cytochromes were lower in the fur mutant, consistent with the transcriptional profiling. Transcriptomic analysis and electrophoretic mobility shift assays revealed a primary regulation network for Fur in WP3. These results suggest that Fur may act as a sensor for anoxic conditions to trigger and influence the anaerobic respiratory system. PMID:24124499

  13. Stability of ferric complexes with 3-hydroxyflavone (flavonol), 5,7-dihydroxyflavone (chrysin), and 3',4'-dihydroxyflavone.

    PubMed

    Engelmann, Mark D; Hutcheson, Ryan; Cheng, I Francis

    2005-04-20

    The acid dissociation and ferric stability constants for complexation by the flavonoids 3-hydroxyflavone (flavonol), 5,7-dihydroxyflavone (chrysin), and 3',4'-dihydroxyflavone in 50:50 (v/v) ethanol/water are determined by pH potentiometric and spectrophotometric titrations and the linear least-squares curve-fitting program Hyperquad. Over the entire range of pH and reagent concentrations spanning the titration experiments, the stoichiometry for iron-flavonoid complex formation was 1:1 for all three flavonoids examined. The three flavonoids were chosen for their hydroxy substitution pattern, with each possessing one of the three most commonly suggested sites for metal binding by the flavonoids. On the basis of the calculated stability constants, the intraflavonoid-binding site competition is illustrated as a function of pH via speciation curves. The curves indicate that the binding site comprised of the 3',4'-hydroxy substitutions, the catecholic site, is most influential for ferric complexation at the physiological pH of 7.4. The possibility for antioxidant activity by flavonoid chelation of ferric iron in the presence of other competitive physiological complexing agents is demonstrated through additional speciation calculations. PMID:15826045

  14. Ferric Maltol Is Effective in Correcting Iron Deficiency Anemia in Patients with Inflammatory Bowel Disease: Results from a Phase-3 Clinical Trial Program

    PubMed Central

    Ahmad, Tariq; Tulassay, Zsolt; Baumgart, Daniel C.; Bokemeyer, Bernd; Büning, Carsten; Howaldt, Stefanie; Stallmach, Andreas

    2014-01-01

    Background: Iron deficiency anemia (IDA) is frequently seen in inflammatory bowel disease. Traditionally, oral iron supplementation is linked to extensive gastrointestinal side effects and possible disease exacerbation. This multicenter phase-3 study tested the efficacy and safety of ferric maltol, a complex of ferric (Fe3+) iron with maltol (3-hydroxy-2-methyl-4-pyrone), as a novel oral iron therapy for IDA. Methods: Adult patients with quiescent or mild-to-moderate ulcerative colitis or Crohn's disease, mild-to-moderate IDA (9.5–12.0 g/dL and 9.5–13.0 g/dL in females and males, respectively), and documented failure on previous oral ferrous products received oral ferric maltol capsules (30 mg twice a day) or identical placebo for 12 weeks according to a randomized, double-blind, placebo-controlled study design. The primary efficacy endpoint was change in hemoglobin (Hb) from baseline to week 12. Safety and tolerability were assessed. Results: Of 329 patients screened, 128 received randomized therapy (64 ferric maltol-treated and 64 placebo-treated patients) and comprised the intent-to-treat efficacy analysis: 55 ferric maltol patients (86%) and 53 placebo patients (83%) completed the trial. Significant improvements in Hb were observed with ferric maltol versus placebo at weeks 4, 8, and 12: mean (SE) 1.04 (0.11) g/dL, 1.76 (0.15) g/dL, and 2.25 (0.19) g/dL, respectively (P < 0.0001 at all time-points; analysis of covariance). Hb was normalized in two-thirds of patients by week 12. The safety profile of ferric maltol was comparable with placebo, with no impact on inflammatory bowel disease severity. Conclusions: Ferric maltol provided rapid clinically meaningful improvements in Hb and showed a favorable safety profile, suggesting its possible use as an alternative to intravenous iron in IDA inflammatory bowel disease. PMID:25545376

  15. The global oxidation state of the upper oceanic crust

    NASA Astrophysics Data System (ADS)

    Rutter, J.; Harris, M.; Coggon, R. M.; Alt, J.; Smith-Duque, C. E.; Teagle, D. A.

    2012-12-01

    The oxidation state of the oceanic crust is an important component of the Earth system. The widespread oxidation of the crust is a major contributor to the redox state of the mantle due to the subduction of hydrothermally altered oceanic crust, which supplies 10 - 25 % of the net ferric iron flux to the global mantle Fe3+/FeTOT budget (Lécuyer and Ricard, 1999). Secondly, the degree of oxidation of the upper oceanic crust provides a measure of the biomass of microbial life sub-basement (Bach and Edwards, 2003). Thirdly, oxidation state analyses of oceanic basalt give information on the environment and relative timings of local hydrothermal alteration events. To date comprehensive measurements of Fe3+/FeTOT for the oceanic crust are lacking. Post crystallisation oxidation processes, occurring predominantly in the upper basaltic layers of the crust, elevate ratios of ferric to total iron (Fe3+/FeTOT) from mantle levels of 0.16 ± 0.01 (Cottrell and Kelley, 2011). Ferrous (Fe2+/) iron is oxidised to ferric (Fe3+/) iron during reaction with oxidised seawater, which circulates through oceanic crust for tens of millions of years following crustal formation. This study integrates published data with new analyses from six ocean crustal boreholes to categorise the global oxidation state of the upper crust. Samples range from <1 to 129 Ma, and represent basalt from medium to superfast spreading centres, depths between <100 - 2000 mbsf, and at a variety of sedimentary cover rates and thicknesses. Results show that by 1 Ma, the Fe3+/FeTOT ratio of the bulk crust is already raised to an average of 0.28 ± 0.07, implying that the oxidation state is established very early in the lifetime of the ocean crust. Post 1 Ma, Fe3+/FeTOT ratios are more variable, reflecting the effects of prolonged exposure to circulating seawater, but are on average ~0.35.

  16. Enhanced photocatalytic activity of sprayed Au doped ferric oxide thin films for salicylic acid degradation in aqueous medium.

    PubMed

    Mahadik, M A; Shinde, S S; Kumbhar, S S; Pathan, H M; Rajpure, K Y; Bhosale, C H

    2015-01-01

    Various doping percentage of Au were successfully introduced into the Fe2O3 photocatalysts via a spray pyrolysis method different. The effect of Au doping on photoelectrochemical, structural, optical and morphological properties of these deposited thin films is studied. The PEC characterization shows that, the photocurrent increases gradually with increasing Au content initially up to 2at.% indicating the maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc=90?A and Voc=220.5mV) and then decreases after exceeding the optimal Au doping content. Therefore, the photocurrent of Au doped Fe2O3 photocatalysts can be adjusted by the Au content. Deposited films are polycrystalline with a rhombohedral crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform. The photocatalytic activities of the Fe2O3 and Au:Fe2O3 photocatalyst were evaluated by photoelectrocatalytic degradation of salicylic acid under sunlight irradiation. The results show that the Au:Fe2O3 thin film photocatalyst exhibited about 45% more degradation of pollutants than the pure Fe2O3. Thus, in Au doped Fe2O3 photocatalysts, the interaction between Au and Fe2O3 reduces the recombination of photogenerated charge carriers and improve the photocatalytic activity. PMID:25496876

  17. Synthesis by the solution combustion process and magnetic properties of iron oxide (Fe 3 O 4 and ?-Fe 2 O 3 ) particles

    Microsoft Academic Search

    Juliano Toniolo; Antonio S. Takimi; Mônica J. Andrade; Renato Bonadiman; Carlos P. Bergmann

    2007-01-01

    This article describes the solution combustion synthesis technique as applicable to iron oxide powder production using urea\\u000a as fuel and ferric nitrate as an oxidizer. It focuses on the thermodynamic modeling of the combustion reaction under different\\u000a fuel-to-oxidant ratios. X-ray diffraction showed magnetite (Fe3O4) and hematite (?-Fe2O3) phase formations for the as-synthesized powders. The smallest crystallite size was obtained by

  18. In situ oxidation of green rusts by deprotonation; wet corrosion and passivation of weathering steels

    NASA Astrophysics Data System (ADS)

    Génin, J.-M. R.; Renard, A.; Ruby, C.; Abdelmoula, M.

    2010-03-01

    Intermediate compounds that belong to the layered double hydroxide family and bear the common name of green rusts (GR) get oxidized through two modes determining material wearing for steel corrosion: either the classical aerial mode where the GR gets dissolved before precipitating into several types of orange ferric oxyhydroxides FeOOH rusts, or the in situ deprotonation of OH- ions within the GR. Hydroxycarbonate, GR(CO32-), [FeII4 FeIII2 (OH)12]2+ • [CO32- • 3H2O]2- produced e.g. in carbonated medium, becomes [FeII6(1-x) FeIII6x O12 H2(7-3x)]2+ • [CO32- • 3H2O]2- which is an oxyhydroxycarbonate where ferric molar ratio x = [FeIII / Fetotal] belongs to the [0, 1] interval; it ends into the "ferric green rust", GR(CO32-)*, [FeIII6 O12 H8]2+ • [CO32- • 3H2O]2- which is in fact orange. These two modes of oxidation of GR that depend upon the flux of oxygen that is used give rise to two different corrosion behaviors. The first one corrodes the material since the GR layer covering the steel surface gets dissolved before precipitating ferric oxyhydroxide. The second mode occurs within the GR layer without destruction; thus, the metal is passivated as for weathering steels.

  19. Oxidation of basaltic tephras: Influence on reflectance in the 1 micron region

    NASA Technical Reports Server (NTRS)

    Farrand, William H.; Singer, Robert B.

    1991-01-01

    As part of a ongoing study into the products of hydrovolcanism, tuffs were examined from the Cerro Colorado and Pavant Butte tuff cones. The former resides in the northeastern corner of the Pinacate Volcanic Field in Sonara, Mexico and the latter is in the Black Rock Desert of southern Utah. Numerous samples were collected and many of these had their Vis/IR reflectance measured. It seems likely that in the palagonite tuffs there is a combination of nanocrystalline ferric oxide phases contributing to the UV absorption edge, but not to the 1 micron band, plus more crystalline ferric oxides which do contribute to that band as well as ferrous iron within unaltered sideromelane which is skewing the band center to longer wavelengths. This work has implications for the study of Mars. The present work indicates that when ferrous and ferric iron phases are both present, their combined spectral contribution is a single band in the vicinity of 1 micron. The center, depth, and width of that feature has potential to be used to gauge the relative proportions of ferrous and ferric iron phases.

  20. Solubility products of amorphous ferric arsenate and crystalline scorodite (FeAsO 4 · 2H 2O) and their application to arsenic behavior in buried mine tailings

    NASA Astrophysics Data System (ADS)

    Langmuir, Donald; Mahoney, John; Rowson, John

    2006-06-01

    Published solubility data for amorphous ferric arsenate and scorodite have been reevaluated using the geochemical code PHREEQC with a modified thermodynamic database for the arsenic species. Solubility product calculations have emphasized measurements obtained under conditions of congruent dissolution of ferric arsenate (pH < 3), and have taken into account ion activity coefficients, and ferric hydroxide, ferric sulfate, and ferric arsenate complexes which have association constants of 10 4.04 (FeH 2AsO 42+), 10 9.86 (FeHAsO 4+), and 10 18.9 (FeAsO 4). Derived solubility products of amorphous ferric arsenate and crystalline scorodite (as log Ksp) are -23.0 ± 0.3 and -25.83 ± 0.07, respectively, at 25 °C and 1 bar pressure. In an application of the solubility results, acid raffinate solutions (molar Fe/As = 3.6) from the JEB uranium mill at McClean Lake in northern Saskatchewan were neutralized with lime to pH 2-8. Poorly crystalline scorodite precipitated below pH 3, removing perhaps 98% of the As(V) from solution, with ferric oxyhydroxide (FO) phases precipitated starting between pH 2 and 3. Between pH 2.18 and 7.37, the apparent log Ksp of ferric arsenate decreased from -22.80 to -24.67, while that of FO (as Fe(OH) 3) increased from -39.49 to -33.5. Adsorption of As(V) by FO can also explain the decrease in the small amounts of As(V)(aq) that remain in solution above pH 2-3. The same general As(V) behavior is observed in the pore waters of neutralized tailings buried for 5 yr at depths of up to 32 m in the JEB tailings management facility (TMF), where arsenic in the pore water decreases to 1-2 mg/L with increasing age and depth. In the TMF, average apparent log Ksp values for ferric arsenate and ferric hydroxide are -25.74 ± 0.88 and -37.03 ± 0.58, respectively. In the laboratory tests and in the TMF, the increasing crystallinity of scorodite and the amorphous character of the coexisting FO phase increases the stability field of scorodite relative to that of the FO to near-neutral pH values. The kinetic inability of amorphous FO to crystallize probably results from the presence of high concentrations of sulfate and arsenate.

  1. Optimizing iron delivery in the management of anemia: patient considerations and the role of ferric carboxymaltose.

    PubMed

    Toblli, Jorge Eduardo; Angerosa, Margarita

    2014-01-01

    With the challenge of optimizing iron delivery, new intravenous (iv) iron-carbohydrate complexes have been developed in the last few years. A good example of these new compounds is ferric carboxymaltose (FCM), which has recently been approved by the US Food and Drug Administration for the treatment of iron deficiency anemia in adult patients who are intolerant to oral iron or present an unsatisfactory response to oral iron, and in adult patients with non-dialysis-dependent chronic kidney disease (NDD-CKD). FCM is a robust and stable complex similar to ferritin, which minimizes the release of labile iron during administration, allowing higher doses to be administered in a single application and with a favorable cost-effective rate. Cumulative information from randomized, controlled, multicenter trials on a diverse range of indications, including patients with chronic heart failure, postpartum anemia/abnormal uterine bleeding, inflammatory bowel disease, NDD-CKD, and those undergoing hemodialysis, supports the efficacy of FCM for iron replacement in patients with iron deficiency and iron-deficiency anemia. Furthermore, as FCM is a dextran-free iron-carbohydrate complex (which has a very low risk for hypersensitivity reactions) with a small proportion of the reported adverse effects in a large number of subjects who received FCM, it may be considered a safe drug. Therefore, FCM appears as an interesting option to apply high doses of iron as a single infusion in a few minutes in order to obtain the quick replacement of iron stores. The present review on FCM summarizes diverse aspects such as pharmacology characteristics and analyzes trials on the efficacy/safety of FCM versus oral iron and different iv iron compounds in multiple clinical scenarios. Additionally, the information on cost effectiveness and data on change in quality of life are also discussed. PMID:25525337

  2. Experience with intravenous ferric carboxymaltose in patients with iron deficiency anemia.

    PubMed

    Bregman, David B; Goodnough, Lawrence T

    2014-04-01

    Erythropoiesis may be limited by absolute or functional iron deficiency or when chronic inflammatory conditions lead to iron sequestration. Intravenous iron may be indicated when oral iron cannot address the deficiency. Ferric carboxymaltose (FCM) is a nondextran iron preparation recently approved in the United States for intravenous treatment of iron deficiency anemia (IDA) in adult patients with intolerance or unsatisfactory response to oral iron or with nondialysis-dependent chronic kidney disease. The full dose is two administrations of up to 750 mg separated by at least 7 days (up to 1500 mg total). FCM can be injected in 7-8 min or diluted in saline for slower infusion. The efficacy and safety of this dose was established in two prospective trials that randomized over 3500 subjects, 1775 of whom received FCM. One trial showed similar efficacy of FCM to an approved intravenous iron regimen (1000 mg of iron sucrose) in 2500 subjects with chronic kidney disease and additional cardiovascular risk factors. The other trial showed superior efficacy of FCM to oral iron in subjects with IDA due to various etiologies (e.g. gastrointestinal or uterine bleeding). In these trials, there was no significant difference between FCM and comparator with respect to an independently adjudicated composite safety endpoint, including death, myocardial infarction, or stroke. A database of 5799 subjects exposed to FCM provided a safety profile acceptable for regulatory approval. Mechanistic studies demonstrated that the transient, asymptomatic reduction in serum phosphate observed following FCM administration results from induction of fibroblast growth factor 23, which in turn induces renal phosphate excretion. An elevated hepcidin level may identify patients with IDA who will not respond to oral iron but will respond to FCM. The ability to administer FCM in two rapid injections or infusions will likely be viewed favorably by patients and healthcare providers. PMID:24688754

  3. The Porphyromonas gingivalis Ferric Uptake Regulator Orthologue Binds Hemin and Regulates Hemin-Responsive Biofilm Development

    PubMed Central

    Seers, Christine A.; Mitchell, Helen L.; Catmull, Deanne V.; Glew, Michelle D.; Heath, Jacqueline E.; Tan, Yan; Khan, Hasnah S. G.; Reynolds, Eric C.

    2014-01-01

    Porphyromonas gingivalis is a Gram-negative pathogen associated with the biofilm-mediated disease chronic periodontitis. P. gingivalis biofilm formation is dependent on environmental heme for which P. gingivalis has an obligate requirement as it is unable to synthesize protoporphyrin IX de novo, hence P. gingivalis transports iron and heme liberated from the human host. Homeostasis of a variety of transition metal ions is often mediated in Gram-negative bacteria at the transcriptional level by members of the Ferric Uptake Regulator (Fur) superfamily. P. gingivalis has a single predicted Fur superfamily orthologue which we have designated Har (heme associated regulator). Recombinant Har formed dimers in the presence of Zn2+ and bound one hemin molecule per monomer with high affinity (Kd of 0.23 µM). The binding of hemin resulted in conformational changes of Zn(II)Har and residue 97Cys was involved in hemin binding as part of a predicted -97C-98P-99L- hemin binding motif. The expression of 35 genes was down-regulated and 9 up-regulated in a Har mutant (ECR455) relative to wild-type. Twenty six of the down-regulated genes were previously found to be up-regulated in P. gingivalis grown as a biofilm and 11 were up-regulated under hemin limitation. A truncated Zn(II)Har bound the promoter region of dnaA (PGN_0001), one of the up-regulated genes in the ECR455 mutant. This binding decreased as hemin concentration increased which was consistent with gene expression being regulated by hemin availability. ECR455 formed significantly less biofilm than the wild-type and unlike wild-type biofilm formation was independent of hemin availability. P. gingivalis possesses a hemin-binding Fur orthologue that regulates hemin-dependent biofilm formation. PMID:25375181

  4. Direct Measurements of the Outer Membrane Stage of Ferric Enterobactin Transport

    PubMed Central

    Newton, Salete M.; Trinh, Vy; Pi, Hualiang; Klebba, Phillip E.

    2010-01-01

    When Gram-negative bacteria acquire iron, the metal crosses both the outer membrane (OM) and the inner membrane, but existing radioisotopic uptake assays only measure its passage through the latter bilayer, as the accumulation of the radionuclide in the cytoplasm. We devised a methodology that exclusively observes OM transport and used it to study the uptake of ferric enterobactin (FeEnt) by Escherichia coli FepA. This technique, called postuptake binding, revealed previously unknown aspects of TonB-dependent transport reactions. The experiments showed, for the first time, that despite the discrepancy in cell envelope concentrations of FepA and TonB (?35:1), all FepA proteins were active and equivalent in FeEnt uptake, with a maximum turnover number of ?5/min. FepA-mediated transport of FeEnt progressed through three distinct phases with successively decreasing rates, and from its temperature dependence, the activation energy of the OM stage was 33–35 kcal/mol. The accumulation of FeEnt in the periplasm required the binding protein and inner membrane permease components of its overall transport system; postuptake binding assays on strains devoid of FepB, FepD, or FepG did not show uptake of FeEnt through the OM. However, fluorescence labeling data implied that FepA was active in the ?fepB strain, suggesting that FeEnt entered the periplasm but then leaked out. Further experiments confirmed this futile cycle; cells without FepB transported FeEnt across the OM, but it immediately escaped through TolC. PMID:20335169

  5. Growth, spectroscopic and physicochemical properties of bis mercury ferric chloride tetra thiocyanate: a nonlinear optical crystal.

    PubMed

    Ramesh, V; Shihabuddeen Syed, A; Jagannathan, K; Rajarajan, K

    2013-05-01

    Single crystal of bis mercury ferric chloride tetra thiocyanate [Hg2FeCl3(SCN)4; (MFCTC)] was grown from ethanol-water (3:1) mixed solvent using slow evaporation solvent technique (SEST) for the first time. The cell parameters of the grown crystal were confirmed by single crystal XRD. The coordination of transition metal ions with the SCN ligand is well-identified using FT-IR spectral analysis. The chemical composition of MFCTC was confirmed using CHNS elemental test. The ESR spectral profile of MFCTC was recorded from 298 K to 110K, which strongly suggests the incorporation of Fe(3+) ion and its environment with respect to SCN ligand. The HPLC chromatogram of MFCTC highlights the purity of the compound. The UV-Vis-NIR studies revealed the ultra violet cut-off wavelength of MFCTC in ethanol as 338 nm. The dielectric constant and dielectric loss of the sample were studied as a function of frequency and temperature. The TGA-DTA and DSC thermal analysis show that the sample is thermally stable up to 234.31 °C, which is comparatively far better than the thermal stability of Hg3CdCl2(SCN)6; (171.3 °C) and other metal-organic coordination complex crystals such as CdHg(SCN)4 (198.5 °C), Hg(N2H4CS)4Mn(SCN)4 (199.06 °C) and Hg(N2H4CS)4Zn(SCN)4 (185 °C). The SHG conversion efficiency of MFCTC is found to be higher than KDP. PMID:23501934

  6. Growth, spectroscopic and physicochemical properties of bis mercury ferric chloride tetra thiocyanate: A nonlinear optical crystal

    NASA Astrophysics Data System (ADS)

    Ramesh, V.; Shihabuddeen Syed, A.; Jagannathan, K.; Rajarajan, K.

    2013-05-01

    Single crystal of bis mercury ferric chloride tetra thiocyanate [Hg2FeCl3(SCN)4; (MFCTC)] was grown from ethanol-water (3:1) mixed solvent using slow evaporation solvent technique (SEST) for the first time. The cell parameters of the grown crystal were confirmed by single crystal XRD. The coordination of transition metal ions with the SCN ligand is well-identified using FT-IR spectral analysis. The chemical composition of MFCTC was confirmed using CHNS elemental test. The ESR spectral profile of MFCTC was recorded from 298 K to 110 K, which strongly suggests the incorporation of Fe3+ ion and its environment with respect to SCN ligand. The HPLC chromatogram of MFCTC highlights the purity of the compound. The UV-Vis-NIR studies revealed the ultra violet cut-off wavelength of MFCTC in ethanol as 338 nm. The dielectric constant and dielectric loss of the sample were studied as a function of frequency and temperature. The TGA-DTA and DSC thermal analysis show that the sample is thermally stable up to 234.31 °C, which is comparatively far better than the thermal stability of Hg3CdCl2(SCN)6; (171.3 °C) and other metal-organic coordination complex crystals such as CdHg(SCN)4 (198.5 °C), Hg(N2H4CS)4Mn(SCN)4 (199.06 °C) and Hg(N2H4CS)4Zn(SCN)4 (185 °C). The SHG conversion efficiency of MFCTC is found to be higher than KDP.

  7. Ferric Uptake Regulator and Its Role in the Pathogenesis of Nontypeable Haemophilus influenzae

    PubMed Central

    Santana, Estevan A.; Szelestey, Blake R.; Newsom, David E.; White, Peter; Mason, Kevin M.

    2013-01-01

    Nontypeable Haemophilus influenzae (NTHi) is a commensal microorganism of the human nasopharynx, and yet is also an opportunistic pathogen of the upper and lower respiratory tracts. Host microenvironments influence gene expression patterns, likely critical for NTHi persistence. The host sequesters iron as a mechanism to control microbial growth, and yet iron limitation influences gene expression and subsequent production of proteins involved in iron homeostasis. Careful regulation of iron uptake, via the ferric uptake regulator Fur, is essential in multiple bacteria, including NTHi. We hypothesized therefore that Fur contributes to iron homeostasis in NTHi, is critical for bacterial persistence, and likely regulates expression of virulence factors. Toward this end, fur was deleted in the prototypic NTHi clinical isolate, 86-028NP, and we assessed gene expression regulated by Fur. As expected, expression of the majority of genes that encode proteins with predicted roles in iron utilization was repressed by Fur. However, 14 Fur-regulated genes encode proteins with no known function, and yet may contribute to iron utilization or other biological functions. In a mammalian model of human otitis media, we determined that Fur was critical for bacterial persistence, indicating an important role for Fur-mediated iron homeostasis in disease progression. These data provide a profile of genes regulated by Fur in NTHi and likely identify additional regulatory pathways involved in iron utilization. Identification of such pathways will increase our understanding of how this pathogen can persist within host microenvironments, as a common commensal and, importantly, as a pathogen with significant clinical impact. PMID:23381990

  8. Analysis of lapine cartilage matrix after radiosynovectomy with holmium-166 ferric hydroxide macroaggregate

    PubMed Central

    Makela, O; Lammi, M; Uusitalo, H; Hyttinen, M; Vuorio, E; Helminen, H; Tulamo, R

    2003-01-01

    Objective: To study the short and long term effects of radiosynovectomy on articular cartilage in growing and mature rabbits. Methods: The articular cartilage of the distal femurs of rabbits was examined four days, two months, and one year after radiosynovectomy with holmium-166 ferric hydroxide macroaggregate ([166Ho]FHMA). Arthritic changes were evaluated from histological sections by conventional and polarised light microscopy, and glycosaminoglycan measurements using safranin O staining, digital densitometry, and uronic acid determination. Proteoglycan synthesis was studied by metabolic [35]sulphate labelling followed by autoradiography, and electrophoretic analysis of extracted proteoglycans. Northern analyses were performed to determine the mRNA levels of type II collagen, aggrecan, and Sox9 in cartilage samples. Results: Radiosynovectomy had no major effect on the histological appearance of articular cartilage in mature rabbits, whereas more fibrillation was seen in [166Ho]FHMA radiosynovectomised knee joints of growing rabbits two months after treatment, but not after one year. Radiosynovectomy did not cause changes in the glycosaminoglycan content of cartilage or in the synthesis or chemical structure of proteoglycans. No radiosynovectomy related changes were seen in the mRNA levels of type II collagen, whereas a transient down regulation of aggrecan and Sox9 mRNA levels was seen in young rabbits two months after [166Ho]FHMA radiosynovectomy. Conclusions: [166Ho]FHMA radiosynovectomy caused no obvious chondrocyte damage or osteoarthritic changes in mature rabbits, but in growing rabbits some transient radiation induced effects were seen—for example, mild cartilage fibrillation and down regulation of cartilage-specific genes. PMID:12480668

  9. Experience with intravenous ferric carboxymaltose in patients with iron deficiency anemia

    PubMed Central

    Goodnough, Lawrence T.

    2014-01-01

    Erythropoiesis may be limited by absolute or functional iron deficiency or when chronic inflammatory conditions lead to iron sequestration. Intravenous iron may be indicated when oral iron cannot address the deficiency. Ferric carboxymaltose (FCM) is a nondextran iron preparation recently approved in the United States for intravenous treatment of iron deficiency anemia (IDA) in adult patients with intolerance or unsatisfactory response to oral iron or with nondialysis-dependent chronic kidney disease. The full dose is two administrations of up to 750 mg separated by at least 7 days (up to 1500 mg total). FCM can be injected in 7–8 min or diluted in saline for slower infusion. The efficacy and safety of this dose was established in two prospective trials that randomized over 3500 subjects, 1775 of whom received FCM. One trial showed similar efficacy of FCM to an approved intravenous iron regimen (1000 mg of iron sucrose) in 2500 subjects with chronic kidney disease and additional cardiovascular risk factors. The other trial showed superior efficacy of FCM to oral iron in subjects with IDA due to various etiologies (e.g. gastrointestinal or uterine bleeding). In these trials, there was no significant difference between FCM and comparator with respect to an independently adjudicated composite safety endpoint, including death, myocardial infarction, or stroke. A database of 5799 subjects exposed to FCM provided a safety profile acceptable for regulatory approval. Mechanistic studies demonstrated that the transient, asymptomatic reduction in serum phosphate observed following FCM administration results from induction of fibroblast growth factor 23, which in turn induces renal phosphate excretion. An elevated hepcidin level may identify patients with IDA who will not respond to oral iron but will respond to FCM. The ability to administer FCM in two rapid injections or infusions will likely be viewed favorably by patients and healthcare providers. PMID:24688754

  10. Computational methods for intramolecular electron transfer in a ferrous-ferric iron complex

    SciTech Connect

    Zarzycki, Piotr P.; Kerisit, Sebastien N.; Rosso, Kevin M.

    2011-07-29

    The limitations of common theoretical and molecular computational approaches for predicting electron transfer quantities were assessed, using an archetypal bridged ferrous-ferric electron transfer system in aqueous solution. The basis set effect on the magnitude of the electronic coupling matrix element computed using the quasi-diabatic method was carefully examined, and it was found that the error related to a poor basis set could exceed the thermal energy at room temperature. A range of approaches to determining the external (solvent) reorganization energy were also investigated. Significant improvements from the Marcus continuum model can be obtained by including dipolar Born-Kirkwood-Onsager correction. In this regard we also found that Klamt’s Conductor-Like Screening Model (COSMO) yields estimations of the external reorganization energy similar to those obtained with explicit solvent molecular dynamics simulations, if the fast-frequency modes are neglected, which makes it an attractive alternative to laborious umbrella sampling simulations. As expected, dielectric saturation observed in the first solvation shell decreases the curvature of the potential energy surface, but it nonetheless remains a quadratic function of the reaction coordinate. The linearity of solvent response to the charge redistribution was assessed by analyzing the energy gap autocorrelation function as well as the solvent density and dipole moment fluctuations. Molecular dynamics was also used to evaluate the sign and magnitude of the solvent reorganization entropy, to determine its effect on the predicted electron transfer rate. Finally, we present a simple way of estimating the vibration frequency along the reaction coordinate, which also enables prediction of the mass dependent isotopic signature of electron-transfer reactions.

  11. Effect of ferric and ferrous iron addition on phosphorus removal and fouling in submerged membrane bioreactors.

    PubMed

    Zhang, Zhenghua; Wang, Yuan; Leslie, Greg L; Waite, T David

    2015-02-01

    The effect of continuously dosing membrane bioreactors (MBRs) with ferric chloride (Fe(III)) and ferrous sulphate (Fe(II)) on phosphorus (P) removal and membrane fouling is investigated here. Influent phosphorus concentrations of 10 mg/L were consistently reduced to effluent concentrations of less than 0.02 mg/L and 0.03-0.04 mg/L when an Fe(III)/P molar ratio of 4.0 and Fe/P molar ratio (for both Fe(II) and Fe(III)) of 2.0 were used, respectively. In comparison, effluent concentrations did not decrease below 1.35 mg/L in a control reactor to which iron was not added. The concentrations of supernatant organic compounds, particularly polysaccharides, were reduced significantly by iron addition. The sub-critical fouling time (tcrit) after which fouling becomes much more severe was substantially shorter with Fe(III) dosing (672 h) than with Fe(II) dosing (1200-1260 h) at Fe/P molar ratios of 2.0 while the control reactor (no iron dosing) exhibited a tcrit of 960 h. Not surprisingly, membrane fouling was substantially more severe at Fe/P ratios of 4. Fe(II) doses yielding Fe/P molar ratios of 2 or less with dosing to the aerobic chamber were found to be optimal in terms of P removal and fouling mitigation performance. In long term operation, however, the use of iron for maintaining appropriately low effluent P concentrations results in more severe irreversible fouling necessitating the application of an effective membrane cleaning regime. PMID:25482913

  12. Optimizing iron delivery in the management of anemia: patient considerations and the role of ferric carboxymaltose

    PubMed Central

    Toblli, Jorge Eduardo; Angerosa, Margarita

    2014-01-01

    With the challenge of optimizing iron delivery, new intravenous (iv) iron–carbohydrate complexes have been developed in the last few years. A good example of these new compounds is ferric carboxymaltose (FCM), which has recently been approved by the US Food and Drug Administration for the treatment of iron deficiency anemia in adult patients who are intolerant to oral iron or present an unsatisfactory response to oral iron, and in adult patients with non-dialysis-dependent chronic kidney disease (NDD-CKD). FCM is a robust and stable complex similar to ferritin, which minimizes the release of labile iron during administration, allowing higher doses to be administered in a single application and with a favorable cost-effective rate. Cumulative information from randomized, controlled, multicenter trials on a diverse range of indications, including patients with chronic heart failure, postpartum anemia/abnormal uterine bleeding, inflammatory bowel disease, NDD-CKD, and those undergoing hemodialysis, supports the efficacy of FCM for iron replacement in patients with iron deficiency and iron-deficiency anemia. Furthermore, as FCM is a dextran-free iron–carbohydrate complex (which has a very low risk for hypersensitivity reactions) with a small proportion of the reported adverse effects in a large number of subjects who received FCM, it may be considered a safe drug. Therefore, FCM appears as an interesting option to apply high doses of iron as a single infusion in a few minutes in order to obtain the quick replacement of iron stores. The present review on FCM summarizes diverse aspects such as pharmacology characteristics and analyzes trials on the efficacy/safety of FCM versus oral iron and different iv iron compounds in multiple clinical scenarios. Additionally, the information on cost effectiveness and data on change in quality of life are also discussed. PMID:25525337

  13. Iron-reducing bacteria accumulate ferric oxyhydroxide nanoparticle aggregates that may support planktonic growth

    SciTech Connect

    Luef, Birgit; Fakra, Sirine C.; Csencsits, Roseann; Wrighton, Kelly C.; Williams, Kenneth H.; Wilkins, Michael J.; Downing, Kenneth H.; Long, Philip E.; Comolli, Luis R.; Banfield, Jillian F.

    2013-02-04

    Iron-reducing bacteria (FeRB) play key roles in anaerobic metal and carbon cycling and carry out biogeochemical transformations that can be harnessed for environmental bioremediation. A subset of FeRB require direct contact with Fe(III) bearing minerals for dissimilatory growth, yet these bacteria must move between mineral particles. Further, they proliferate in planktonic consortia during biostimulation experiments. Thus, a key question is how such organisms can sustain growth under these conditions. Here we characterized planktonic microbial communities sampled from an aquifer in Rifle, Colorado, USA close to the peak of iron reduction following in situ acetate amendment. Samples were cryo-plunged on site and subsequently examined using correlated 2- and 3- dimensional cryogenic transmission electron microscopy (cryo-TEM) and scanning transmission X-ray microscopy (STXM). Most cells had their outer membranes decorated with up to 150 nm diameter aggregates composed of a few nm wide amorphous, Fe-rich nanoparticles. Fluorescent in situ hybridization of lineage-specific probes applied to rRNA of cells subsequently imaged via cryo-TEM identified Geobacter spp., a well studied group of FeRB. STXM results at the Fe L2,3 absorption edges indicate that nanoparticle aggregates contain a variable mixture of Fe(II)-Fe(III), and are generally enriched in Fe(III). Geobacter bemidjiensis cultivated anaerobically in the laboratory on acetate and hydrous ferric oxyhydroxides also accumulated mixed valence nanoparticle aggregates. In field-collected samples, FeRB with a wide variety of morphologies were associated with nano-aggregates, indicating that cell-surface Fe(III) accumulation may be a general mechanism by which FeRB can grow while in planktonic suspension.

  14. Solar physical vapor deposition preparation and microstructural characterization of TiO2 based nanophases for dye-sensitized solar cell applications.

    PubMed

    Negrea, Denis; Ducu, Catalin; Moga, Sorin; Malinovschi, Viorel; Monty, Claude J A; Vasile, Bogdan; Dorobantu, Dorel; Enachescu, Marian

    2012-11-01

    Titanium dioxide exists in three crystalline phases: anatase, rutile and brookite. Although rutile is thermodynamically more stable, anatase is considered as the most favorable phase for photocatalysis and solar energy conversion. Recent studies have shown a significant improvement of light harvesting and overall solar conversion efficiency of anatase nanoparticles in dye-sensitized solar cells (DSSCs) when using a mixture of anatase and rutile phases (10-15% rutile). TiO2 nanopowders have been prepared by a solar physical vapor deposition process (SPVD). This method has been developed in Odeillo-Font Romeu France using "heliotron" solar reactors working under concentrated sunlight in 2 kW solar furnaces. By controlling reactor's atmosphere type (air/argon) and gas pressure, several types of anatase/rutile nanophases have been obtained with slightly different microstructural properties and morphological characteristics. X-ray diffraction analyses (XRD) were performed on precursor and on the SPVD obtained nanopowders. Information concerning their phase composition and coherence diffraction domain (crystallites size and strain) was obtained. Nanopowders morphology has been studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). PMID:23421278

  15. Modeling the Nanophase Structural Dynamics of Phenylated Sulfonated Poly Ether Ether Ketone Ketone (Ph-SPEEKK) Membranes as a Function of Hydration

    SciTech Connect

    Lins, Roberto D.; Devanathan, Ramaswami; Dupuis, Michel

    2011-03-03

    Solvated phenylated sulfonated poly ether ether ketone ketone (Ph-SPEEKK) membranes in the presence of hydronium ions were modeled by classical molecular dynamics simulations. The characterization of the nanophase structure and dynamics of such membranes was carried out as a function of the water content lambda, where lambda is the number of water molecules per sulfonate group, for lambda values of 3.5, 6, 11, 25, and 40. Analysis of pair correlation functions supports the experimental observation of membrane swelling upon hydration as well the increase in water and hydronium ion diffusion with increasing lambda. While the average number of hydrogen bonds between hydronium ions and sulfonate groups is dramatically affected by the hydration level, the average lifetime of the hydrogen bonds remains essentially constant. The membrane is found to be relatively rigid and its overall flexibility shows little dependence on water content. Compared to Nafion, water and ion diffusion coefficients are considerably smaller at lower hydration levels and room temperature. However, at higher lambda values of 25 and 40 these coefficients are comparable to those in Nafion at a lambda value of 16. This study also shows that water diffusion in Ph-SPEEKK membranes at low hydration levels can be significantly improved by raising the temperature with important implications for proton conductivity.

  16. Method for fluorination of uranium oxide

    DOEpatents

    Petit, George S. (Oak Ridge, TN)

    1987-01-01

    Highly pure uranium hexafluoride is made from uranium oxide and fluorine. The uranium oxide, which includes UO.sub.3, UO.sub.2, U.sub.3 O.sub.8 and mixtures thereof, is introduced together with a small amount of a fluorine-reactive substance, selected from alkali chlorides, silicon dioxide, silicic acid, ferric oxide, and bromine, into a constant volume reaction zone. Sufficient fluorine is charged into the zone at a temperature below approximately 0.degree. C. to provide an initial pressure of at least approximately 600 lbs/sq. in. at the ambient atmospheric temperature. The temperature is then allowed to rise in the reaction zone until reaction occurs.

  17. Biomineralization of As(V)-hydrous ferric oxyhydroxide in microbial mats of an acid-sulfate-chloride geothermal spring, Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Inskeep, William P.; Macur, Richard E.; Harrison, Gregory; Bostick, Benjamin C.; Fendorf, Scott

    2004-08-01

    Acid-sulfate-chloride (pH˜3) geothermal springs in Yellowstone National Park (YNP) often contain Fe(II), As(III), and S(-II) at discharge, providing several electron donors for chemolithotrophic metabolism. The microbial populations inhabiting these environments are inextricably linked with geochemical processes controlling the behavior of As and Fe. Consequently, the objectives of the current study were to (i) characterize Fe-rich microbial mats of an ASC thermal spring, (ii) evaluate the composition and structure of As-rich hydrous ferric oxides (HFO) associated with these mats, and (iii) identify microorganisms that are potentially responsible for mat formation via the oxidation of Fe(II) and or As(III). Aqueous and solid phase mat samples obtained from a spring in Norris Basin, YNP (YNP Thermal Inventory NHSP35) were analyzed using a complement of chemical, microscopic and spectroscopic techniques. In addition, molecular analysis (16S rDNA) was used to identify potentially dominant microbial populations within different mat locations. The biomineralization of As-rich HFO occurs in the presence of nearly equimolar aqueous As(III) and As(V) (˜12 ?M), and ˜ 48 ?M Fe(II), forming sheaths external to microbial cell walls. These solid phases were found to be poorly ordered nanocrystalline HFO containing mole ratios of As(V):Fe(III) of 0.62 ± 0.02. The bonding environment of As(V) and Fe(III) is consistent with adsorption of arsenate on edge and corner positions of Fe(III)-OH octahedra. Numerous archaeal and bacterial sequences were identified (with no closely related cultured relatives), along with several 16S sequences that are closely related to Acidimicrobium, Thiomonas, Metallosphaera and Marinithermus isolates. Several of these cultured relatives have been implicated in Fe(II) and or As(III) oxidation in other low pH, high Fe, and high As environments (e.g. acid-mine drainage). The unique composition and morphologies of the biomineralized phases may be useful as modern-day analogs for identifying microbial life in past Fe-As rich environments.

  18. Microwave Assisted Synthesis of Iron(III) Oxyhydroxides/Oxides Characterized Using Transmission Electron Microscopy, X-ray Diffraction, and X-ray Absorption Spectroscopy

    PubMed Central

    Parsons, J.G.; Luna, C.; Botez, C.E.; Elizalde, J.; Gardea-Torresdey, J.L.

    2009-01-01

    Microwave assisted synthesis of iron oxide/oxyhydroxide nanophases was conducted using iron(III) chloride titrated with sodium hydroxide at seven different temperatures from 100°C to 250°C with pulsed microwaves. From the XRD results, it was determined that there were two different phases synthesized during the reactions which were temperature dependent. At the lower temperatures, 100°C and 125°C, it was determined that an iron oxyhydroxide chloride was synthesized. Whereas, at higher temperatures, at 150°C and above, iron(III) oxide was synthesized. From the XRD, we also determined the FWHM and the average size of the nanoparticles using the Scherrer equation. The average size of the nanoparticles synthesized using the experimental conditions were 17, 21, 12, 22, 26, 33, 28 nm, respectively for the reactions from 100°C to 250°C. The particles also had low anisotropy indicating spherical nanoparticles, which was later confirmed using TEM. Finally, XAS studies show that the iron present in the nanophase was present as iron(III) coordinated to six oxygen atoms in the first coordination shell. The higher coordination shells also conform very closely to the ideal or bulk crystal structures. PMID:20161181

  19. The influence of ferric iron and hydrogen on Fe-Mg interdiffusion in ferropericlase ((Mg,Fe)O) in the lower mantle

    NASA Astrophysics Data System (ADS)

    Otsuka, Kazuhiko; Karato, Shun-ichiro

    2015-04-01

    Both ferric iron (Fe3+) and hydrogen (H+) have important influence on several transport properties of minerals such as diffusion. We determined the influence of Fe3+ and H+ on Fe-Mg interdiffusion in (Mg,Fe)O at 1,673-1,873 K and 5-24 GPa under the anhydrous and hydrous conditions using the diffusion couple technique. The diffusion couples consist of single crystals of ferropericlase ((Mg,Fe)O) and periclase (MgO) with Mg/(Mg + Fe) ratios ranging from 0.44 to 1.0. The oxygen fugacity was controlled by the following assemblages of metal and oxide: Fe-FeO, Ni-NiO, Mo-MoO2, and Re-ReO2. After the diffusion experiments, hydrogen (H+) concentrations were measured using the FTIR spectroscopy. Fe3+ concentrations were measured using the flank method. Under the conditions investigated, Fe-Mg interdiffusivity increases strongly with Fe3+ and modestly with H+ and the influence of H+ relative to that of Fe3+ on Fe-Mg interdiffusion decreases with temperature. Our results show that, under both anhydrous and hydrous conditions, the dominant defect responsible for diffusion is the same suggesting that H+ enhances Fe-Mg interdiffusivity by enhancing the mobility of vacancies at the M-site. Our results indicate that the influence of Fe3+ likely dominates at temperatures expected for the normal lower mantle conditions ( T > 1,900 K), while the influence of both Fe3+ and H+ is important at lower temperature environments such as near the subduction zone. We also estimated the vacancy diffusivity based on Fe-Mg interdiffusion and vacancy concentration estimated from the charge neutrality condition with Fe3+. Both Fe-Mg interdiffusivity and vacancy diffusivities are reasonably consistent with values estimated from previous experimental and theoretical studies.

  20. Enhancement of a solar photo-Fenton reaction with ferric-organic ligands for the treatment of acrylic-textile dyeing wastewater.

    PubMed

    Soares, Petrick A; Batalha, Mauro; Souza, Selene M A Guelli U; Boaventura, Rui A R; Vilar, Vítor J P

    2015-04-01

    Literature describes a kinetic mineralization profile for most of acrylic-textile dyeing wastewaters using a photo-Fenton reaction characterized by a slow degradation process and high reactants consumption. This work tries to elucidate that the slow decay on DOC concentration is associated with the formation of stable complexes between Fe(3+) and textile auxiliary products, limiting the photoreduction of Fe(3+). This work also evaluates the enhancement of a solar photo-Fenton reaction through the use of different ferric-organic ligands applied to the treatment of a simulated acrylic-textile dyeing wastewater, as a pre-oxidation step to enhance its biodegradability. The photo-Fenton reaction was negatively affected by two dyeing auxiliary products: i) Sera(®) Tard A-AS, a surfactant mainly composed of alkyl dimethyl benzyl ammonium chloride and ii) Sera(®) Sperse M-IW, a dispersing agent composed of polyglycol solvents. The catalytic activity of the organic ligands toward the ferrous-catalysed system followed this order: Fe(III)-Oxalate > Fe(III)-Citrate > Fe(III)-EDDS, and all were better than the traditional photo-Fenton reaction. Different design parameters such as iron concentration, pH, temperature, flow conditions, UV irradiance and H2O2 addition strategy and dose were evaluated. The ferrioxalate induced photo-Fenton process presented the best results, achieving 87% mineralization after 9.3 kJUV L(-1) and allowing to work until near neutral pH values. As expected, the biodegradability of the textile wastewater was significantly enhanced during the photo-Fenton treatment, achieving a value of 73%, consuming 32.4 mM of H2O2 and 5.7 kJUV L(-1). PMID:25618444

  1. Uptake of anti-anemic substance ferric-sorbitol-citrate by normal and malignant cells and its effects on expression of transferrin receptor 1 and ferritin.

    PubMed

    Prutki, Maja; Poljak-Blazi, Marija; Mihaljevic, Branka; Orescanin, Visnja; Zarkovic, Neven

    2006-12-01

    Iron-containing antianemic drug ferric-sorbitol-citrate (FSC) inhibits the proliferation of various cancer cell lines in vitro and causes a regression of experimental murine tumors in vivo but does not affect the proliferation of nonmalignant cells. Growth modification caused by FSC iron involves a diminished expression of Bcl-2 and an overexpression of p53 proto-oncogene, accompanied by an increased incidence of apoptosis. Aiming to evaluate further the activity principle of the anticancer effects of this antianemic drug, in this study, we analyzed the utilization of iron from FSC and the effects of FSC iron on transferrin receptor 1 (TfR1) and ferritin expression. Without FSC iron, all the cell lines had an equal expression of TfR1, but if cultured in FSC-supplemented medium, human colon SW620 and laryngeal carcinoma Hep cells exhibited a lower expression of TfR1-positive cells than nonmalignant Wi38 fibroblasts and pancreatic carcinoma MiaPaCa2 cells. The most sensitive to FSC iron were colon carcinoma SW620 cells, whereas Wi38 fibroblasts were not sensitive at all. Increased iron uptake by colon carcinoma cells was noticed in the first 3 hours of the incubation with FSC iron, whereas higher FSC iron concentrations and longer incubation also impaired ferritin expression in SW260 colon carcinoma cells. Thus, the anticancer ability of FSC could result from its higher initial utilization of iron and consecutive negative signal for the expression of TfR1 in tumor cells. Tumor cells containing lower amounts of ferritin are probably more sensitive to oxidative stress caused by iron overload, whereas FSC iron itself was proven to be chemically stable and did not induce lipid peroxidation. PMID:17257079

  2. The influence of ferric iron and hydrogen on Fe-Mg interdiffusion in ferropericlase ((Mg,Fe)O) in the lower mantle

    NASA Astrophysics Data System (ADS)

    Otsuka, Kazuhiko; Karato, Shun-ichiro

    2014-11-01

    Both ferric iron (Fe3+) and hydrogen (H+) have important influence on several transport properties of minerals such as diffusion. We determined the influence of Fe3+ and H+ on Fe-Mg interdiffusion in (Mg,Fe)O at 1,673-1,873 K and 5-24 GPa under the anhydrous and hydrous conditions using the diffusion couple technique. The diffusion couples consist of single crystals of ferropericlase ((Mg,Fe)O) and periclase (MgO) with Mg/(Mg + Fe) ratios ranging from 0.44 to 1.0. The oxygen fugacity was controlled by the following assemblages of metal and oxide: Fe-FeO, Ni-NiO, Mo-MoO2, and Re-ReO2. After the diffusion experiments, hydrogen (H+) concentrations were measured using the FTIR spectroscopy. Fe3+ concentrations were measured using the flank method. Under the conditions investigated, Fe-Mg interdiffusivity increases strongly with Fe3+ and modestly with H+ and the influence of H+ relative to that of Fe3+ on Fe-Mg interdiffusion decreases with temperature. Our results show that, under both anhydrous and hydrous conditions, the dominant defect responsible for diffusion is the same suggesting that H+ enhances Fe-Mg interdiffusivity by enhancing the mobility of vacancies at the M-site. Our results indicate that the influence of Fe3+ likely dominates at temperatures expected for the normal lower mantle conditions (T > 1,900 K), while the influence of both Fe3+ and H+ is important at lower temperature environments such as near the subduction zone. We also estimated the vacancy diffusivity based on Fe-Mg interdiffusion and vacancy concentration estimated from the charge neutrality condition with Fe3+. Both Fe-Mg interdiffusivity and vacancy diffusivities are reasonably consistent with values estimated from previous experimental and theoretical studies.

  3. Free radical scavenging capacity and inhibition of lipid oxidation of wines, grape juices and related polyphenolic constituents

    Microsoft Academic Search

    Concepción Sánchez-Moreno; José A. Larrauri; Fulgencio Saura-Calixto

    1999-01-01

    The antioxidant activity of grape juices, wines made from the same lot as juices and their major polyphenolic constituents was measured by the inhibition of lipid oxidation (ferric-thiocyanate) and free radical scavenging (2,2-diphenyl-1-picrylhydrazyl) methods. dl-?-Tocopherol and 3-tertiary-butyl-4-hydroxyanisole (BHA) were used as references. The inhibition of lipid oxidation of the standards followed the order: rutin = ferulic acid > tannic acid

  4. Manganese peroxidase from the basidiomycete Phanerochaete chrysosporium: spectral characterization of the oxidized states and the catalytic cycle

    Microsoft Academic Search

    Hiroyuki Wariishi; Lakshmi Akileswaran; Michael H. Gold

    1988-01-01

    Manganese peroxidase (MnP), an extracellular heme enzyme from the lignin-degrading fungus Phanerochaete chrysosporium, catalyzes the Mn(II)-dependent oxidation of a variety of phenols. Herein, the authors spectroscopically characterize the oxidized states of MnP compounds I, II, and III and clarify the role of Mn in the catalytic cycle of the enzyme. Addition of 1 equiv of HâOâ to the native ferric

  5. Investigation of the low-affinity oxidation site for exogenous electron donors in the Mn-depleted photosystem II complexes

    Microsoft Academic Search

    V. N. Kurashov; E. R. Lovyagina; D. Yu. Shkolnikov; M. K. Solntsev; M. D. Mamedov; B. K. Semin

    2009-01-01

    In the manganese-depleted photosystem II (PSII[?Mn]) preparations, oxidation of exogenous electron donors is carried out through the high-affinity (HA) and the low-affinity (LA) sites. This paper investigates the LA oxidation site in the PSII(?Mn) preparations where the HA, Mn-binding site was blocked with ferric cations [[11] B.K. Semin, M.L. Ghirardi, M. Seibert, Blocking of electron donation by Mn(II) to YZ•

  6. Photocatalytic oxidation of methyl orange in water phase by immobilized TiO2-carbon nanotube nanocomposite photocatalyst

    NASA Astrophysics Data System (ADS)

    Dong, Yinmao; Tang, Dongyan; Li, Chensha

    2014-03-01

    We developed an immobilized carbon nanotube (CNT)-titanium dioxide (TiO2) heterostructure material for the photocatalytic oxidation of methyl orange in aqueous phase. The catalyst material was prepared via sol-gel method using multi-walled CNTs grown on graphite substrate as carriers. The multi-walled CNTs were synthesized from thermal decomposing of hydrocarbon gas directly on thin graphite plate, forming immobilized 3-dimensional network of CNTs. The nanophase TiO2 was synthesized coating on CNTs to form "coral"-shaped nanocomposite 3-dimensional network on graphite substrate, thus bringing effective porous structure and high specific surface area, and possessing the merit of dispersive powder photocatalysts, which is the fully available surface area, while adapting the requirement for clean and convenient manipulation as an immobilized photocatalyst. Moreover, the CNT-TiO2 heterostructure reduced the electron-hole pair recombination rate and enhanced the photoabsorption and the adsorption ability, resulting in elevating the photocatalysis efficiency. These synergistic effects due to the hybrid nature of the materials and interphase interaction greatly improved the catalytic activity, and demonstrated superior photocatalytic performances. Our work can be a significant inspiration for developing hybrid nano-phase materials to realize sophisticated functions, and bear tremendous significance for the development and applications of semiconductor nano-materials.

  7. Comparative evaluation of Ferric Sulfate, Electrosurgical and Diode Laser on human primary molars pulpotomy: an “in-vivo” study

    PubMed Central

    Yadav, P; Indushekar, KR; Saraf, BG; Sheoran, N; Sardana, D

    2014-01-01

    Background and aims: Despite modern advances in the prevention of dental caries and increased understanding of the importance of maintaining the natural primary dentition, many teeth are still lost prematurely. This can lead to malocclusion with aesthetic, phonetic and functional problems that may be transient or permanent. Therefore, maintaining the integrity and health of the oral tissues is the primary objective of pulp treatment. Pulpotomy has remained an acceptable and mainstay treatment in preserving the vitality of primary tooth and prolonging its life till the permanent successor erupts. Various materials and techniques are available for pulpotomy on primary molars; all with some advantages and disadvantages. The present study was carried out on 45 primary molars to evaluate and compare the clinical and radiographic success of diode laser, electrosurgical and ferric sulfate pulpotomy over a period of 9 months. Materials (Subjects) and Methods: The forty five primary molars were randomly and equally divided into three treatment groups which were as follows: Group A: 15 primary molars treated with 15.5% Ferric sulfate Group B: 15 primary molars treated with electrosurgical unit and Group C: 15 primary molars treated with diode laser. All teeth in three categories were followed up clinically and radiographically at 1, 3, 6 and 9 months post treatment and the findings were recorded on the prepared proforma Results: Clinically, 86.6% success rate was found in ferric sulfate group whereas 100% success rate was found in electrosurgical and diode laser groups. Radiographically, 80% success rate was found in all the three groups at the end of 9 months with internal resorption being the most common cause of failure after pulpotomy. Conclusions: Thus, electrosurgery and diode lasers appear to be acceptable alternative to pharmacotherapeutic pulpotomy agents. PMID:24771970

  8. Potentially life-threatening phosphate diabetes induced by ferric carboxymaltose injection: a case report and review of the literature.

    PubMed

    Vandemergel, Xavier; Vandergheynst, Frédéric

    2014-01-01

    We report the case of a 45-year-old female patient who developed phosphate diabetes after administration of ferric carboxymaltose. Ten days after the second dose, she complained of intense fatigue and blood analysis showed a phosphate plasma level of 0.93?mg/dL with phosphate excretion rate of 23%. She received phosphate supplementation which resulted in phosphate clearance improvement which persisted for two months. We reviewed other cases described in the literature and would draw attention to this rare but potentially life-threatening side effect. PMID:25478250

  9. Assessment of mapping exposed ferrous and ferric iron compounds using Skylab-EREP data. [Pisgah Crater, California

    NASA Technical Reports Server (NTRS)

    Vincent, R. (principal investigator); Wagner, H.; Pillars, W.; Bennett, C.

    1976-01-01

    The author has identified the following significant results. The S190B color photography is as useful as LANDSAT data for the mapping of color differences in the rocks and soils of the terrain. An S192 ratio of 0.79 - 0.89 and 0.93 - 1.05 micron bands produced an apparently successful delineation of ferrous, ferric, and other materials, in agreement with theory and ratio code studies. From an analysis of S191 data, basalt and dacite were separated on the basis of differences in spectral emissivity in the 8.3 - 12 micron region.

  10. The relation of fO?, ferric-ferrous ratio (R), and physical properties of four natural clinoamphiboles

    E-print Network

    Clowe, Celia Ann

    1987-01-01

    -magnetite-quartz (FM(}), and graphite-methane (CCH4) buffers at 650'C and 1 kb. Runs were also conducted at 500'C and 400'C and 1 kb to increase the understanding of amphibole stabi 1- ity limits. The ferric-ferrous ratio for each sample was determined using... the single dissolution technique of Fritz and Popp ( 1985). The effect of increasing R on physical properties, such as unit cell parameters and optical properties, of the amphiboles was determined. The unit cell parameters of each sample were determined...

  11. Potentially Life-Threatening Phosphate Diabetes Induced by Ferric Carboxymaltose Injection: A Case Report and Review of the Literature

    PubMed Central

    Vandemergel, Xavier; Vandergheynst, Frédéric

    2014-01-01

    We report the case of a 45-year-old female patient who developed phosphate diabetes after administration of ferric carboxymaltose. Ten days after the second dose, she complained of intense fatigue and blood analysis showed a phosphate plasma level of 0.93?mg/dL with phosphate excretion rate of 23%. She received phosphate supplementation which resulted in phosphate clearance improvement which persisted for two months. We reviewed other cases described in the literature and would draw attention to this rare but potentially life-threatening side effect. PMID:25478250

  12. Influence of organic matter on the transport of Cryptosporidium parvum oocysts in a ferric oxyhydroxide-coated quartz sand saturated porous medium

    USGS Publications Warehouse

    Abudalo, R.A.; Ryan, J.N.; Harvey, R.W.; Metge, D.W.; Landkamer, L.

    2010-01-01

    To assess the effect of organic matter on the transport of Cryptosporidium parvum oocysts in a geochemically heterogeneous saturated porous medium, we measured the breakthrough and collision efficiencies of oocysts as a function of dissolved organic matter concentration in a flow-through column containing ferric oxyhydroxide-coated sand. We characterized the surface properties of the oocysts and ferric oxyhydroxide-coated sand using microelectrophoresis and streaming potential, respectively, and the amount of organic matter adsorbed on the ferric oxyhydroxide-coated sand as a function of the concentration of dissolved organic matter (a fulvic acid isolated from Florida Everglades water). The dissolved organic matter had no significant effect on the zeta potential of the oocysts. Low concentrations of dissolved organic matter were responsible for reversing the charge of the ferric oxyhydroxide-coated sand surface from positive to negative. The charge reversal and accumulation of negative charge on the ferric oxyhydroxide-coated sand led to increases in oocyst breakthrough and decreases in oocyst collision efficiency with increasing dissolved organic matter concentration. The increase in dissolved organic matter concentration from 0 to 20 mg L-1 resulted in a two-fold decrease in the collision efficiency. ?? 2009 Elsevier Ltd.

  13. Exploring metal effects and synergistic interactions of ferric stimulation on azo-dye decolorization by new indigenous Acinetobacter guillouiae Ax-9 and Rahnella aquatilis DX2b.

    PubMed

    Ng, I-Son; Xu, Fangxin; Ye, Chiming; Chen, Bor-Yann; Lu, Yinghua

    2014-02-01

    The first-attempt study deciphered metal-interacting effects on dye-decolorizing capabilities of indigenous bioelectricity-generating strains, Acinetobacter guillouiae Ax-9 and Rahnella aquatilis DX2b. Most of the metallic ions were inhibitory to color removal capabilities of these strains. However, with supplementation of 5 mM ferric chloride, specific decolorization rate (SDR) of Ax-9 increased by 55.48% compared to Fe(3+)-free conditions. In contrast, SDR of DX2b decreased 75.35% due to the inhibition of ferric chloride. On the other hand, ferric citrate could stimulate SDR of DX2b for 21.5% at same dosage. Enzymatic assay indicated that Fe reductase activity was consistent with synergistic effects of ferric chloride on Ax-9, and ferric citrate on DX2b. Protein analysis via SDS-PAGE and identification of Tandem MS/MS afterwards showed that outer membrane protein (Omp) primarily deals with decolorization as a channeling regulation. Moreover, molecular modeling and bioinformatics data also provided detailed evidences to confirm the biological significance of Omp. PMID:23743733

  14. Effect of ferric oxyhydroxide grain coatings on the transport of bacteriophage PRD1 and Cryptosporidium parvum oocysts in saturated porous media

    USGS Publications Warehouse

    Abudalo, R.A.; Bogatsu, Y.G.; Ryan, J.N.; Harvey, R.W.; Metge, D.W.; Elimelech, M.

    2005-01-01

    To test the effect of geochemical heterogeneity on microorganism transport in saturated porous media, we measured the removal of two microorganisms, the bacteriophage PRD1 and oocysts of the protozoan parasite Cryptosporidium parvum, in flow-through columns of quartz sand coated by different amounts of a ferric oxyhydroxide. The experiments were conducted over ranges of ferric oxyhydroxide coating fraction of ?? = 0-0.12 for PRD1 and from ?? = 0-0.32 for the oocysts at pH 5.6-5.8 and 10-4 M ionic strength. To determine the effect of pH on the transport of the oocysts, experiments were also conducted over a pH range of 5.7-10.0 at a coating fraction of ?? = 0.04. Collision (attachment) efficiencies increased as the fraction of ferric oxyhydroxide coated quartz sand increased, from ?? = 0.0071 to 0.13 over ?? = 0-0.12 for PRD1 and from ?? = 0.059 to 0.75 over ?? = 0-0.32 for the oocysts. Increasing the pH from 5.7 to 10.0 resulted in a decrease in the oocyst collision efficiency as the pH exceeded the expected point of zero charge of the ferric oxyhydroxide coatings. The collision efficiencies correlated very well with the fraction of quartz sand coated by the ferric oxyhydroxide for PRD1 but not as well for the oocysts. ?? 2005 American Chemical Society.

  15. Influence of the addition of sulphate and ferric ions in a methanogenic anaerobic packed-bed reactor treating gasoline-contaminated water.

    PubMed

    Fernandes, B S; Chinalia, F A; Sarti, A; Silva, A J; Foresti, E; Zaiat, M

    2006-01-01

    Benzene, toluene and xylene (BTX) are relatively soluble aromatic compounds of gasoline. Gasoline storage tank leakages generally lead to an extensive contamination of groundwater. In the natural environment for instance, these compounds might be biodegraded under a variety of reducing potentials. The objective of this work was to examine the influence of the addition of sulphate and Fe(OH)3 in a methanogenic horizontal-flow anaerobic immobilized-biomass reactor treating gasoline-contaminated water. Three different conditions were evaluated: methanogenic, sulphidogenic and sulphidogenic with the addition of ferric ions. Methanogenic condition showed the higher BTX degradation rates and the addition of sulphate negatively affected BTX removal rates with the production of H2S. However, the addition of ferric ions resulted in the precipitation of sulphur, improving BTX degradation by the consortium. Metanosphaera sp., Methanosarcina barkeri and Methanosaeta concilii were identified in the consortium by means of 16S and directly related to the addition of ferric ions. PMID:16939094

  16. An ellipsometry study on the effect of aluminium chloride and ferric chloride formulations on mucin layers adsorbed at hydrophobic surfaces.

    PubMed

    Hamit-Eminovski, Jildiz; Eskilsson, Krister; Arnebrant, Thomas

    2010-07-01

    Ellipsometry was used to investigate the effect of polyaluminium chloride (PAC) formulations of different degrees of hydrolysation on an adsorbed mucin film. The results were compared to the effect of aluminium chloride (AlCl(3)) and ferric chloride. A compaction of the mucin film took place upon addition of the formulations and this occurred to different extents and at different concentrations for the different formulations. The compaction of PAC of a low degree of hydrolysis behaved similarly to AlCl(3). PAC of a high degree of hydrolysis showed a greater compaction effect than the other aluminium formulations. The initial compaction concentration was found to be 0.001 mM which is less than previously found for aluminium-mucin complex formation in bulk. The reversibility of the compaction was also investigated. The compaction of the mucin film was found to be partly reversible for AlCl(3) and PAC of low degree of hydrolysis. No reversibility was observed for the formulations of PAC of high hydrolysis grade or for ferric chloride. The results are consistent with previously observed effects of PAC of a low degree of hydrolysis on bacterial surfaces where a compaction of surface polymers was indicated by the reduced range of repulsive steric interactions. PMID:20432077

  17. Marked difference in the electronic structure of cyanide-ligated ferric protoglobins and myoglobin due to heme ruffling.

    PubMed

    Van Doorslaer, Sabine; Tilleman, Lesley; Verrept, Ben; Desmet, Filip; Maurelli, Sara; Trandafir, Florin; Moens, Luc; Dewilde, Sylvia

    2012-08-20

    Electron paramagnetic resonance experiments reveal a significant difference between the principal g values (and hence ligand-field parameters) of the ferric cyanide-ligated form of different variants of the protoglobin of Methanosarcina acetivorans (MaPgb) and of horse heart myoglobin (hhMb). The largest principal g value of the ferric cyanide-ligated MaPgb variants is found to be significantly lower than for any of the other globins reported so far. This is at least partially caused by the strong heme distortions as proven by the determination of the hyperfine interaction of the heme nitrogens and mesoprotons. Furthermore, the experiments confirm recent theoretical predictions [Forti, F.; Boechi, L., Bikiel, D., Martí, M.A.; Nardini, M.; Bolognesi, M.; Viappiani, C.; Estrin, D.; Luque, F. J. J. Phys. Chem. B 2011, 115, 13771-13780] that Phe(G8)145 plays a crucial role in the ligand modulation in MaPgb. Finally, the influence of the N-terminal 20 amino-acid chain on the heme pocket in these protoglobins is also proven. PMID:22877248

  18. Preparation of activated carbons from Iris tectorum employing ferric nitrate as dopant for removal of tetracycline from aqueous solutions.

    PubMed

    Li, Gang; Zhang, Dongsheng; Wang, Man; Huang, Ji; Huang, Lihui

    2013-12-01

    Ferric nitrate was employed to modify activated carbon prepared from Iris tectorum during H?PO? activation and ability of prepared activated carbon for removal of tetracycline (TC) was investigated. The properties of the activated carbon samples with or without ferric nitrate, ITAC-Fe and ITAC, were measured by scanning electron microscopy (SEM), N? adsorption/desorption isotherms, Fourier transform infrared spectroscopy (FTIR) and Boehm's titration. The results showed that mixing with iron increased the BET surface area, total pore volume and the adsorption capacity as compared to the original carbon. FTIR and Boehm's titration suggested that ITAC-Fe was characteristic of more acidic functional groups than ITAC. Adsorption of TC on both samples exhibited a strong pH-dependent behavior and adsorption capacity reduced rapidly with the increasing solution pH. The adsorption kinetics agreed well with the pseudo-second-order model and the adsorption isotherms data were well described by Langmuir model with the maximum adsorption capacity of 625.022 mg/g for ITAC and 769.231 mg/g for ITAC-Fe. The present work suggested that ITAC-Fe could be used to remove tetracycline effectively from aqueous solutions. PMID:24021870

  19. Properties and coagulation performance of coagulant poly-aluminum-ferric-silicate-chloride in water and wastewater treatment.

    PubMed

    Gao, Bao-yu; Yue, Qin-yan; Wang, Bing-jian

    2006-01-01

    An efficient inorganic polymer coagulant, poly-aluminum-ferric-silicate-chloride (PAFSC), was developed using two approaches: (i) hydroxylation of the mixture of AlCl3, FeCl3 and fresh polysilicic acid in different Al/Fe/Si molar ratios to obtain PAFSCc and (ii) hydroxylated poly-aluminum-iron-chloride (PAFC) combined with aged polysilicic acid in different Al/Fe/Si ratios to produce PAFSCm. The properties of PAFSC in comparison with polyaluminum silicate chloride (PASC) and polyferric silicate chloride (PAFC) were characterized by various experimental methods. The effect of Al/Fe/Si molar ratio on the hydrolysis-polymerization process of Al (III) and Fe (III) in PAFSC solutions was examined by pH titration, and the effect of Al/Fe/Si molar ratio on electrokinetic mobility of PAFSC was studied by Zeta potential measurement. The laboratory experiments were performed to evaluate the PAFSC in comparison with polyaluminum chloride (PAC) for the coagulation of synthetic water samples, actual surface water and wastewater. The results show that interactions exist among aluminum species, ferric species and polysilicic acid, and the Al/Fe/Si molar ratio affects the Zeta potential of the hydrolyzate and the coagulating performance. PAFSC achieved a better water treatment result than PAC. At the same basicity (B) value and Al/Fe/Si ratio, PAFSCc has better coagulation performance than PAFSCm. PAFSC is a new type and high efficiency composite inorganic polymer coagulant. PMID:16854802

  20. Cloning and characterization of the iutA gene which encodes ferric aerobactin receptor from marine Vibrio species.

    PubMed

    Murakami, K; Fuse, H; Takimura, O; Inoue, H; Yamaoka, Y

    2000-01-01

    The iutA gene from marine Vibrio species SD004, which encoded a ferric aerobactin receptor for the uptake of iron(III), was cloned onto a multicopy plasmid, pUC 18, in Escherichia coli. Identification of the positive clone was achieved on the basis of its deferrization activity and was detected as a halo formation on the chrome azurol S (CAS)-containing selective plate. Nucleotide sequence analysis of the cloned DNA fragment revealed an open reading frame (ORF) which encoded a polypeptide of 706 amino acid residues, and the deduced molecular mass of this polypeptide was 77.906 kD. The amino acid sequence showed a 41% homology with that of the lutA protein from E. coli. The cloned gene was iutA, which encoded the ferric aerobactin receptor. Another incomplete ORF was found 100 bp upstream of the iutA gene, which was homologous (31 out of 49 amino acids) with the C-terminal region of the luc D protein of E. coli. It is suggested that aerobactin biosynthesis and the transport genes are located tandemly on the Vibrio chromosome and may form an aerobactin operon. PMID:10756518

  1. Effect of ferric sorbitol citrate (FSC) administration on NF-kappaB in macrophages and spleen cells of rats.

    PubMed

    Bosnjak, Berislav; Kati?, Masa; Hrvaci?, Boska; Zupanovi?, Zeljko; Poljak-Blazi, Marija

    2004-02-01

    Interaction of iron metabolism and the immune system is complex and pathological changes in one system affect the other. Ferric sorbitol citrate (FSC), non-toxic compound of ferric ions with sorbitol and citrate. has immunomodulatory effect in treated mice. We investigated an effect of FSC on NF-kappaB expression/activation in peritoneal macrophages and spleen cells of rats. TNF-alpha concentrations in sera of control and FSC intraperitoneal (i.p.) treated Wistar rats were measured by ELISA. Furthermore, peritoneal macrophages (PM) were counted and splenocytes were isolated. PM and splenocytes were lysed and their cytoplasmic and nuclear fractions were separated by centrifugation. The influence of FSC on NF-kappaB expression and/or activity as well as expression of its inhibitor IkappaB-alpha was measured by Western blot. 1.5 and three hours after FSC treatment TNF-alpha level in sera was significantly (p < or = 0.05) increased. Activation of transcription factor NF-kappaB in PM was detected three hours after treatment, followed by significant increment in PM number. In splenocytes NF-kappaB was activated six and 48 hours after FSC application. The results indicate that, after i.p. application, FSC acts as a modulator of the immune system activating NF-kappaB in PM. PM consequently secrete TNF-alpha that activates NF-kappaB in splenocytes. PMID:15106731

  2. Eleven-years-long record of ferric hydroxide sedimentation in Satsuma Iwo-Jima island, Kagoshima, Japan

    NASA Astrophysics Data System (ADS)

    Ueshiba, T.; Kiyokawa, S.; Goto, S.; Oguri, K.; Ito, T.; Ikehara, M.; Yamaguchi, K. E.; Nagata, T.; Ninomiya, T.; Ikegami, F.

    2011-12-01

    Satsuma Iwo-Jima island is active in volcanic activity located about 40 km south of Kyushu Island, Japan. It has many hot springs, and is surrounded by patches of reddish brown and white colored seawater. Nagahama Bay, a small port located in the southern part of the island, retains reddish brown seawater and precipitates ferric hydroxide (Ninomiya and Kiyokawa, 2009). We conducted multidisciplinary study to investigate mechanisms and histories of precipitation of the sediments. From 2009 to 2011, we obtained 1.5m-long core samples in the bay that record sedimentation of mainly ferric hydroxide during the last 11~13 years since dredging in 1998. We compare their stratigraphy with (a) 11 years meteorological data and (b) volcanic activity record in that period. Stratigraphy: Thirteen short cores (<1m long) were collected from Nagahama Bay. The lower unit contains three layers of white and pink tuff beds (T1, T2 and T3) with thickness of 1~9cm. The upper unit mainly contains sand bed and reddish-brown mud. The tuff beds are mainly composed of volcanic glass. Sand bed is essentially a mixture of felsic rock fragments, volcanic glass, and ferric-rich fine materials. The reddish brown sediment between T1 and T2 has very fine orange-colored laminations (1~2mm thick/each). (a) Meteorological data: 11-years-long meteorological data of the Satsuma Iwo-Jima island suggest that heavy rainfalls (precipitation over 100mm/day) occurred in June 2000 (189mm/day), June 2001 (124.5mm/day), and June 2002 (122mm/day), and that three events of strong typhoon occurred in 2004 (maximum wind speed: 40.3m/s, 54.3m/s and 44.6m/s), 2005 (43.3m/s), and 2007 (50.2m/s). These meteorological events are reflected in, sometimes disturb, the sediment record. (b) Volcanic data: Volcanic activity has occurred from 1997 (Shinohara, 2002) to October 2004 (Japan Meteorological Agency, 2010). During that time, ash was spewed out from and deposited near the volcano. Tuffaceous beds in the sediments of Nagahama Bay record such volcanic activity, however reworking of sediments by meteorological events are found to obscure such record. Conclusions: We found two sedimentological events that play important role in forming sediments in Nagahama Bay; heavy rainfall and strong typhoon. The thick tuff beds (T1, T2 and T3) formed by reworking sediments induced by heavy rainfall. The sand bed formed by hydrodynamic mixings due to strong typhoon events in 2004. The ferric hydroxide-rich surface sediments are very loose and easily flown by hydrodynamic currents in the bay. However, once particles of the ferric hydrate precipitate at the seafloor, only strong current could move them. Neap tide may enhance their sedimentation and thus help to form strata.

  3. Survey of ferric reductase transcription and activity in Pisum sativum accessions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iron (Fe) is an essential element for the growth of plants. While Fe is not limiting in most soils (it makes up approximately 5% of total soil minerals), Fe availability to plants in aerated, calcareous soils near neutral or basic pH can be severely limited as Fe oxidizes to form less soluble ferri...

  4. Soluble ferric iron as an effective protective agent against UV radiation: Implications for early life

    NASA Astrophysics Data System (ADS)

    Gómez, Felipe; Aguilera, Angeles; Amils, Ricardo

    2007-11-01

    Some recent MER Rover Opportunity results on ancient sedimentary rocks from Mars describe sandstones originated from the chemical weathering of olivine basalts by acidic waters [Squyres, S.W., Knoll, A.H., 2005. Earth Planet. Sci. Lett. 240, 1-10]. The absence of protective components in early Mars atmosphere forced any possible primordial life forms to deal with high doses of UV radiation. A similar situation occurred on the primitive Earth during the development of early life in the Archean [Berkner, L.V., Marshall, L.C., 1965. J. Atmos. Sci. 22 (3), 225-261; Kasting, J.F., 1993. Science 259, 920-926]. It is known that some cellular and/or external components can shield organisms from damaging UV radiation or quench its toxic effects [Olson, J.M., Pierson, B.K., 1986. Photosynth. Res. 9, 251-259; García-Pichel, F., 1998. Origins Life Evol. B 28, 321-347; Cockell, C., Rettberg, P., Horneck, G., Scherer, K., Stokes, M.D., 2003. Polar Biol. 26, 62-69]. The effectiveness of iron minerals for UV protection has also been reported [Phoenix, V.R., Konhauser, K.O., Adams, D.G., Bottrell, S.H., 2001. Geology 29 (9), 823-826], but nothing is known about the effect of iron in solution. Here we demonstrate the protective effect of soluble ferric iron against UV radiation on acidophilic photosynthetic microorganisms. These results offer an interesting alternative means of protection for life on the surface of early Mars and Earth, especially in light of the geochemical conditions in which the sedimentary minerals, jarosite and goethite, recently reported by the MER missions, were formed [Squyres, S.W., Arvidson, R.E., Bell III, J.F., Brückner, J., Cabrol, N.A., Calvin, W., Carr, M.H., Christensen, P.R., Clark, B.C., Crumpler, L., Des Marais, D.J., d'Uston, C., Economou, T., Farmer, J., Farrand, W., Folkner, W., Golombek, M., Gorevan, S., Grant, J.A., Greeley, R., Grotzinger, J., Haskin, L., Herkenhoff, K.E., Hviid, S., Johnson, J., Klingelhöfer, G., Knoll, A.H., Landis, G., Lemmon, M., Li, R., Madsen, M.B., Malin, M.C., McLennan, S.M., McSween, H.Y., Ming, D.W., Moersch, J., Morris, R.V., Parker, T., Rice Jr., J.W., Richter, L., Rieder, R., Sims, M., Smith, M., Smith, P., Soderblom, L.A., Sullivan, R., Wänke, H., Wdowiak, T., Wolff, M., Yen, A., 2004. Science 306, 1698-1703; Klingelhöfer, G., Morris, R.V., Bernhardt, B., Schröder, C., Rodionov, D.S., de Souza Jr., P.A., Yen, A., Gellert, R., Evlanov, E.N., Zubkov, B., Foh, J., Bonnes, U., Kankeleit, E., Gütlich, P., Ming, D.W., Renz, F., Wdowiak, T., Squyres, S.W., Arvidson, R.E., 2004. Science 306, 1740-1745].

  5. Effects of fasting and/or oxidizing and reducing agents on absorption of neptunium from the gastrointestinal tract of mice and adult or neonatal rats

    SciTech Connect

    Sullivan, M.F.; Ruemmler, P.S.; Ryan, J.L.

    1984-12-01

    Neptunium-237(V) nitrate was administered by gavage to groups of fed or fasted adult and 5-day-old rats. Some groups also received the oxidants quinhydrone or ferric iron and others received the reducing agent ferrous iron. Adult mice received ferric or ferrous iron and /sup 235/Np. When the adult rats were killed at 7 days after gavage, measurements showed that, compared with rats that were fed, a 24-hr fast caused a fivefold increase in /sup 237/Np absorption and retention. Both quinhydrone and ferric iron caused an even greater increase in absorption in both fed and fasted rats. Ferrous iron, on the other hand, decreased absorption in fasted rats to values lower than those obtained in fed rats. Similar results were obtained in mice treated with /sup 235/Np and either ferric or ferrous iron. The effects of ferric and ferrous iron on neptunium absorption by neonatal rats were similar to their effects on adult animals but of lesser magnitude. These results are consistent with the hypothesis that Np(V), when given in small mass quantities to fed animals, is reduced in the gastrointestinal tract to Np(IV), which is less well absorbed than Np(V).

  6. XRD, HRTEM, magnetic and Mössbauer studies on chemically prepared Fe 3+-doped nanoparticles of cerium oxide

    Microsoft Academic Search

    S. Acharya; A. Bandyopadhyay; S. Modak; S. Mukherjee; D. Das; P. K. Chakrabarti

    2009-01-01

    Nanocrystalline samples of Fe-doped cerium oxide (Ce0.90Fe0.1O2) are prepared by sol–gel method. The precursor materials used for the synthesis are ferric nitrate and cerium nitrate. The as-prepared samples is annealed at different temperatures to obtain the sample with different particle sizes. The crystallographic phases of the nanocrystalline materials have been confirmed by X-ray diffractograms (XRD). The sizes of the nanoparticles

  7. Facile methods to synthesize nanaosized iron oxide colloidal dispersion and its characterization

    Microsoft Academic Search

    Kan-Sen Chou; Song-Juh Lee

    2009-01-01

    In this study, we develop two experimental procedures to synthesize a nanosized ?-Fe2O3 colloidal suspension within a relatively short reaction time. In the first method, we use ferric chloride as the precursor, both NaOH and urea as the precipitant, and polyvinyl pyrrolidone (PVP) as the protecting agent; we find that by adding ferrous ion (Fe2+), nanosized ?-iron oxide colloids are

  8. Inhibition of pyrite oxidation by a phospholipid in the presence of silicate.

    PubMed

    Kargbo, David M; Atallah, George; Chatterjee, Sabyasachi

    2004-06-15

    The influence of sodium silicate on the ability of a diacetylene-containing phospholipid (23:2 diyne PC) to inhibit the oxidation of pyrite at pH 2 and pH 6 was investigated. The phospholipid used has previously been reported to show up to 80% suppression of pyrite oxidation and to show excellent stability down to at least pH 2. Pyrite was leached with a solution containing Fe3+ but no coating agent and three different solutions or treatments: a lipid treatment, a silicate treatment, and a lipid + silicate treatment. Pyrite oxidation was based on iron (Fe3+, Fe2+) leached out of a continuous-flow porous-bed reactor system. The results show that at pH 6 the silicate and lipid both bind strongly to the pyrite surfaces, providing a barrier that inhibits the production and subsequent release of oxidation products. The lipid is superior to the silicate in suppressing pyrite oxidation at both pH 2 and pH 6. Also, the presence of silicates decreased the ability for the lipid to suppress pyrite oxidation, both at pH 2 and pH 6. The reaction mechanism for pyrite oxidation at pH 2 is first order for pyrite leached by solutions containing only ferric, ferric together with silicate, and ferric combined with silicate and lipid. The only treatment that effectively prevented pyrite oxidation at pH 2 was the lipid treatment. The Fe speciation results are supported by both SEM images and EDS calculations. PMID:15260345

  9. Copper Oxide Nanoparticles Induce Autophagic Cell Death in A549 Cells

    PubMed Central

    Zhao, Yan; Guo, Feng; Jiang, Chengyu

    2012-01-01

    Metal oxide nanoparticles (NPs) are among the most highly produced nanomaterials, and have many diverse functions in catalysis, environmental remediation, as sensors, and in the production of personal care products. In this study, the toxicity of several widely used metal oxide NPs such as copper oxide, silica, titanium oxide and ferric oxide NPs, were evaluated In vitro. We exposed A549, H1650 and CNE-2Z cell lines to metal oxide NPs, and found CuO NPs to be the most toxic, SiO2 mild toxic, while the other metal oxide NPs had little effect on cell viability. Furthermore, the autophagic biomarker LC3-II significantly increased in A549 cells treated with CuO NPs, and the use of the autophagy inhibitors wortmannin and 3-methyladenin significantly improved cell survival. These results indicate that the cytoxicity of CuO NPs may involve the autophagic pathway in A549 cells. PMID:22916263

  10. A novel homogeneous Fenton-like system with Fe(III)–phosphotungstate for oxidation of organic compounds at neutral pH values

    Microsoft Academic Search

    Changha Lee; David L. Sedlak

    2009-01-01

    Ferric ion (Fe[III]) catalyzes the decomposition of hydrogen peroxide (H2O2) into strong oxidants such as hydroxyl radical (OH) and ferryl ion (Fe[IV]) through the redox cycling of the iron couple (Fe[II]\\/Fe[III]). The use of these reactions for the catalytic oxidation of organic compounds is usually limited to the acidic pH region due to the low solubility of Fe(III) and the

  11. Progress in the development and use of ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment

    Microsoft Academic Search

    Jia-Qian Jiang; Barry Lloyd

    2002-01-01

    This paper reviews the progress in preparing and using ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment. The literature revealed that due to its unique properties (viz. strong oxidizing potential and simultaneous generation of ferric coagulating species), ferrate(VI) salt can disinfect microorganisms, partially degrade and\\/or oxidise the organic and inorganic impurities, and remove suspended\\/colloidal particulate materials

  12. The Exclusion of D2O from the Hydration Sphere of FeSO4 \\\\cdot 7H2O Oxidized by Thiobacillus ferrooxidans

    Microsoft Academic Search

    Norman Lazaroff

    1983-01-01

    Infrared spectra demonstrate that neither FeSO4 \\\\cdot 7H2O nor its bacterial or abiotic hydrated oxidation products incorporate deuterium in acid D2O solutions. Deuterium exchange occurred as bridging OD when bacterially oxidized iron was precipitated from D2O solutions as ferric hydroxysulfates. The exclusion of deuterium depended upon the stabilization of aquated Fe(II) and Fe(III) complexes by sulfate ions in outer-sphere coordination

  13. Nanophase iron phosphate, iron arsenate, iron vanadate, and iron molybdate minerals synthesized within the protein cage of ferritin.

    PubMed

    Polanams, Jup; Ray, Alisha D; Watt, Richard K

    2005-05-01

    Nanoparticles of iron phosphate, iron arsenate, iron molybdate, and iron vanadate were synthesized within the 8 nm interior of ferritin. The synthesis involved reacting Fe(II) with ferritin in a buffered solution at pH 7.4 in the presence of phosphate, arsenate, vanadate, or molybdate. O2 was used as the oxidant to deposit the Fe(III) mineral inside ferritin. The rate of iron incorporation into ferritin was stimulated when oxo-anions were present. The simultaneous deposition of both iron and the oxo-anion was confirmed by elemental analysis and energy-dispersive X-ray analysis. The ferritin samples containing iron and one of the oxo-anions possessed different UV/vis spectra depending on the anion used during mineral formation. TEM analysis showed mineral cores with approximately 8 nm mineral particles consistent with the formation of mineral phases inside ferritin. PMID:15847428

  14. Structure and reactivity of As(III)- and As(V)-rich schwertmannites and amorphous ferric arsenate sulfate from the Carnoulès acid mine drainage, France: Comparison with biotic and abiotic model compounds and implications for As remediation

    NASA Astrophysics Data System (ADS)

    Maillot, Fabien; Morin, Guillaume; Juillot, Farid; Bruneel, Odile; Casiot, Corinne; Ona-Nguema, Georges; Wang, Yuheng; Lebrun, Sophie; Aubry, Emmanuel; Vlaic, Gilberto; Brown, Gordon E.

    2013-03-01

    Poorly ordered nanocrystalline hydroxysulfate minerals of microbial origin, such as schwertmannite, Fe8O8(OH)6SO4, are important arsenic scavengers in sulfate-rich acid mine drainage (AMD) environments. However, despite the fact that As(III) and As(V) have been shown to sorb on schwertmannite, little is known about the actual mechanism of arsenic scavenging processes after microbial Fe(II) oxidation in AMD environments. The major focus of the present study is to determine the molecular-level structure of poorly ordered As(III) and As(V) bearing Fe oxyhydroxysulfate minerals from the Carnoulès AMD, France, which exhibits exceptional As(III) concentrations. Powder X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy were used to compare field samples with a large set of synthetic analogs prepared via biotic or abiotic pathways, with As/Fe ratios typical of minerals and mineraloids ranging from nanocrystalline schwertmannite to amorphous hydroxysulfate compounds. Our results yield further evidence for the poisoning effect of As(V) in limiting the nucleation of schwertmannite. For initial dissolved As(V)/Fe(III) molar ratios ?0.2, amorphous Fe(III)-As(V) hydroxysulfate forms, with a local structure consistent with that of amorphous ferric arsenate. EXAFS data for this amorphous material are consistent with corner-sharing FeO6 octahedra to which AsO4 tetrahedra attach via double-corner 2C linkages. For As(V)/Fe(III) molar ratios lower than 0.2, As(V) binds to schwertmannite via 2C surface complexes. In contrast with the As(V)-containing samples, As(III) has a lower affinity for schwertmannite following its nucleation, as this mineral phase persists up to an initial As(III)/Fe(III) molar ratio of 0.6. EXAFS data indicate that during the precipitation process, As(III) forms dominantly 2C surface complexes on schwertmannite surfaces, likely on the sides of double-chains of Fe(III)(O,OH)6 octahedra, with a smaller proportion of edge-sharing 2E surface complexes at the apexes of these chains. Importantly, dissolved As(V) concentrations in contact with As(V)-schwertmannite or ferric arsenate were found to be ˜10 times lower than dissolved As(III) concentrations in contact with As(III)-schwertmannite for similar As/Fe ratios in the solid phase. Consequently, remediation of As-rich AMD environments is greatly improved by oxidation of As(III) to As(V).

  15. Decompression mechanism of ferric iron reduction in tektite melts during their formation in the impact process

    Microsoft Academic Search

    O. A. Lukanin; A. A. Kadik

    2007-01-01

    The analysis of available data on the Fe3+\\/Fe2+ ratio of impact-produced glasses showed that tektites and some other types of impact glasses are reduced compared with the\\u000a precursor target material. Possible reasons for the change in the degree of iron oxidation in the impact process are still\\u000a debatable. Based on the analysis of redox reactions in relatively simple systems with

  16. Performance evaluation of ALCAN-AASF50-ferric coated activated alumina and granular ferric hydroxide (GFH) for arsenic removal in the presence of competitive ions in an active well :Kirtland field trial - initial studies.

    SciTech Connect

    Neidel, Linnah L.; Krumhansl, James Lee; Siegel, Malcolm Dean; Khandaker, Nadim Reza

    2006-01-01

    This report documents a field trial program carried out at Well No.15 located at Kirtland Air Force Base, Albuquerque, New Mexico, to evaluate the performance of two relatively new arsenic removal media, ALCAN-AASF50 (ferric coated activated alumina) and granular ferric hydroxide (US Filter-GFH). The field trial program showed that both media were able to remove arsenate and meet the new total arsenic maximum contaminant level (MCL) in drinking water of 10 {micro}g/L. The arsenate removal capacity was defined at a breakthrough effluent concentration of 5 {micro}g/L arsenic (50% of the arsenic MCL of 10 {micro}g/L). At an influent pH of 8.1 {+-} 0.4, the arsenate removal capacity of AASF50 was 33.5 mg As(V)/L of dry media (29.9 {micro}g As(V)/g of media on a dry basis). At an influent pH of 7.2 {+-} 0.3, the arsenate removal capacity of GFH was 155 mg As(V)/L of wet media (286 {micro}g As(V)/g of media on a dry basis). Silicate, fluoride, and bicarbonate ions are removed by ALCAN AASF50. Chloride, nitrate, and sulfate ions were not removed by AASF50. The GFH media also removed silicate and bicarbonate ions; however, it did not remove fluoride, chloride, nitrate, and sulfate ions. Differences in the media performance partly reflect the variations in the feed-water pH between the 2 tests. Both the exhausted AASF50 and GFH media passed the Toxicity Characteristic Leaching Procedure (TCLP) test with respect to arsenic and therefore could be disposed as nonhazardous waste.

  17. Mechanisms of iron-based catalysis investigated using model compounds

    SciTech Connect

    Linehan, J.C.; Matson, D.W.; Darab, J.G.; Autrey, S.T.; Franz, J.A.; Camaioni, D.M.

    1994-08-01

    The catalytic mechanism of highly active, nanophase, iron-based coal liquefaction catalysts was investigated using a series of model compounds. The iron-oxide phases ferric oxyhydroxysulfate (OHS), 6-line ferrihydrite, hematite, and goethite, were evaluated as catalyst precursors with systematically substituted diphenylmethanes in the presence of a hydrogen donating solvent. The activity of the catalysts was observed to be dependent upon the functionality on the model compounds. The results of these model compound studies and their relationship to possible reaction mechanisms are presented.

  18. Breadboard wash water renovation system. [using ferric chloride and ion exchange resins to remove soap and dissolved salts

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A total wash water renovation system concept was developed for removing objectionable materials from spacecraft wash water in order to make the water reusable. The breadboard model system described provides for pretreatment with ferric chloride to remove soap by chemical precipitation, carbon adsorption to remove trace dissolved organics, and ion exchange for removal of dissolved salts. The entire system was put into continuous operation and carefully monitored to assess overall efficiency and equipment maintenance problems that could be expected in actual use. In addition, the capacity of the carbon adsorbers and the ion-exchange resin was calculated and taken into consideration in the final evaluation of the system adequacy. The product water produced was well within the Tentative Wash Water Standards with regard to total organic carbon, conductivity, urea content, sodium chloride content, color, odor, and clarity.

  19. Identification of a positively charged platform in Staphylococcus aureus HtsA that is essential for ferric staphyloferrin A transport.

    PubMed

    Cooper, John D; Hannauer, Mélissa; Marolda, Cristina L; Briere, Lee-Ann K; Heinrichs, David E

    2014-08-12

    In response to iron starvation, Staphylococcus aureus secretes both staphyloferrin A and staphyloferrin B, which are high-affinity iron-chelating molecules. The structures of both HtsA and SirA, the ferric-staphyloferrin A [Fe(III)-SA] and ferric-staphyloferrin B [Fe(III)-SB] receptors, respectively, have recently been determined. The structure of HtsA identifies a novel form of ligand entrapment composed of many positively charged residues. Through ionic interactions, the binding pocket appears highly adapted for the binding of the highly anionic siderophore SA. However, biological validation of the importance of the nine SA-interacting residues (six arginines, one tyrosine, one histidine, and one lysine) has not been previously performed. Here, we mutated each of the Fe(III)-SA-interacting residues in HtsA and found that substitutions R104A, R126A, H209A, R306A, and R306K resulted in a reduction of binding affinity of HtsA for Fe(III)-SA. While mutation of almost all proposed ligand-interacting residues decreased the ability of S. aureus cells to transport (55)Fe(III)-SA, S. aureus expressing HtsA R104A, R126A, R306A, and R306K showed the greatest transport defects and were incapable of growth in iron-restricted growth media in a SA-dependent manner. These three residues cluster together and, relative to other residues in the binding pocket, move very little between the apo and closed holo structures. Their essentiality for receptor function, together with structural information, suggests that they form a positively charged platform that is required for initial contact with the terminal carboxyl groups of the two citrates in the Fe(III)-SA complex. This is a likely mechanism by which HtsA discerns iron-bound SA from iron-free SA. PMID:25050909

  20. Results of passive and active immunization directed against ferric aerobactin in experimental enterobacterial infections in mice and chickens.

    PubMed

    Le Roy, D; Crouzier, C; Dho-Moulin, M; Dumont, A S; Bouchet, A; Lafont, J P; Andremont, A

    1995-02-01

    Production of aerobactin has been reported to be a virulence factor in members of the family Enterobacteriaceae. To investigate the protection afforded by humoral immunity directed towards aerobactin in infectious diseases caused by aerobactin-producing strains, we tested the efficacy of mAbAERO1, a murine monoclonal antibody directed to ferric aerobactin, which, in vitro, was found to impair the growth of aerobactin-dependent strains of Enterobacteriaceae under iron-limited conditions. The mortality of mice experimentally infected with the aerobactin-producing strains Escherichia coli V2019 (LD50 = 3.5 x 10(5) CFU/mice) or Klebsiella pneumoniae Caroli (LD50 = 1.3 CFU/mice) was not reduced when 1 mg of mAbAERO1 was injected intravenously 1 h before or 1 h after bacterial challenge. Nor was mortality reduced after challenge with either E. coli V2019 or K. pneumoniae Caroli, even though the active immunization of mice with purified FeAero (ferric aerobactin) conjugated with thyroglobulin as followed by a rise in systemic anti-FeAero antibodies. Lastly, chicks born of hens immunized with FeAero showed evidence of antibody transmission towards FeAero, but were not protected when challenged with E. coli MT78, an aerobactin-producing strain highly virulent for chickens. Therefore, under the experimental conditions tested, humoral immunity against aerobactin appeared to play only a minor role in protection against infections caused by aerobactin-producing members of the family Enterobacteriaceae. However, other experimental models should be tested to confirm these observations. PMID:7652210

  1. Bioavailability and the mechanisms of intestinal absorption of iron from ferrous ascorbate and ferric polymaltose in experimental animals

    SciTech Connect

    Johnson, G.; Jacobs, P. (Univ. of Cape Town Leukaemia Centre, Observatory (South Africa))

    1990-11-01

    The comparative bioavailability from matching quantities of iron in the form of ferrous ascorbate or ferric polymaltose was defined in rats. Studies were carried out in the intact animals under basal conditions and also when requirements for this metal were either increased or decreased by manipulating stores or erythropoietic activity. No significant difference was found in the total quantity of iron absorbed from either salt or complex under any of these circumstances, suggesting that the mucosal mechanism regulating the overall process was common to both. However, the rate of transfer from the lumen into portal blood was distinctive, reaching a maximum with salt at 30 min compared to 24 h for the complex. To explore the possibility that iron from the two sources was initially handled by different subcellular pathways, the radiolabeled compounds were instilled into loops of bowel that had been isolated between ligatures in vivo. Enterocytes were harvested and fractionated, and incorporation into ferritin and transferrin was determined using RIA. From salt, iron appeared rapidly in duodenal but not ileal ferritin, whereas mucosal transferrin increased under conditions of stimulated absorption, suggesting that this protein may act as a shuttle for the metal. In contrast, iron from polymaltose showed a cumulative incorporation into duodenal ferritin over time that correlated with iron absorption, defined by the appearance of radiolabel in the serum and in the carcass; a similar pattern was demonstrable in ileal mucosal cells. Conversely, binding of iron to transferrin was minimal. No iron polymaltose was found within the mucosal cells. It is suggested that the low rate of iron transfer from this ferric complex may reflect its extracellular breakdown in the lumen of the gastrointestinal tract.

  2. The potential for phosphorus release across the sediment-water interface in an eutrophic reservoir dosed with ferric sulphate.

    PubMed

    Perkins, R G; Underwood, G J

    2001-04-01

    Alton Water, Suffolk, UK is a pumped storage reservoir that has a history of cyanobacterial blooms. Dosing of the input water with ferric sulphate to control external phosphorus loading has occurred since 1983. A detailed study of the sediment chemistry of the site was carried out between May 1995 and July 1997. Sequential phosphorus fraction analysis indicated a decrease along the length of the reservoir in sediment labile phosphorus content from 0.62 to 0.08 mg P g-1 dw and iron-bound phosphorus content from 3.22 to 0.46 mg P g-1 dw. These gradients positively correlated with water column chlorophyll a concentrations reported in a parallel study. Labile and iron-bound sediment phosphorus contents were in a dynamic equilibrium due to diffusional release, contributing to internal loading to the water column. Equilibrium phosphorus concentrations (EPC) determined from phosphorus adsorption capacity (PAC) experiments were lower inside the bunded region (0.01-0.03 mg P-PO4 l-1) where iron content was greatest compared to outside the bund (0.15-0.20 mg P-PO4 l-1) suggesting greater potential for diffusional release of phosphorus at the latter site. PAC experiments indicated that anaerobic and pH-mediated loadings were of less importance than diffusional release, although the latter may have contributed to internal loading in the main reservoir. Sulphate concentrations may act to increase the potential for anaerobic internal loading near to the pumped input in microstratified sediment. Sediment iron content decreased from 250 +/- 13.1 to 51 +/- 4.0 mg Fe g-1 dw across the line of a constructed bund at the north-west end near to the pumped input, which indicated successful control of dispersal of the fine ferric floc. The management implications with regard to phosphorus loadings indicated by these results are discussed. PMID:11317886

  3. Bioavailability and the mechanisms of intestinal absorption of iron from ferrous ascorbate and ferric polymaltose in experimental animals.

    PubMed

    Johnson, G; Jacobs, P

    1990-11-01

    The comparative bioavailability from matching quantities of iron in the form of ferrous ascorbate or ferric polymaltose was defined in rats. Studies were carried out in the intact animals under basal conditions and also when requirements for this metal were either increased or decreased by manipulating stores or erythropoietic activity. No significant difference was found in the total quantity of iron absorbed from either salt or complex under any of these circumstances, suggesting that the mucosal mechanism regulating the overall process was common to both. However, the rate of transfer from the lumen into portal blood was distinctive, reaching a maximum with salt at 30 min compared to 24 h for the complex. To explore the possibility that iron from the two sources was initially handled by different subcellular pathways, the radiolabeled compounds were instilled into loops of bowel that had been isolated between ligatures in vivo. Enterocytes were harvested and fractionated, and incorporation into ferritin and transferrin was determined using RIA. From salt, iron appeared rapidly in duodenal but not ileal ferritin, whereas mucosal transferrin increased under conditions of stimulated absorption, suggesting that this protein may act as a shuttle for the metal. In contrast, iron from polymaltose showed a cumulative incorporation into duodenal ferritin over time that correlated with iron absorption, defined by the appearance of radiolabel in the serum and in the carcass; a similar pattern was demonstrable in ileal mucosal cells. Conversely, binding of iron to transferrin was minimal. No iron polymaltose was found within the mucosal cells. It is suggested that the low rate of iron transfer from this ferric complex may reflect its extracellular breakdown in the lumen of the gastrointestinal tract. PMID:2209759

  4. Induction of hepatic and renal metallothionein synthesis by ferric nitrilotriacetate in mice: the role of MT as an antioxidant

    SciTech Connect

    Min, Kyong-Son [Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180 (Japan)]. E-mail: min@nutr.kobegakuin.ac.jp; Morishita, Fumio [Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180 (Japan); Tetsuchikawahara, Noriko [Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180 (Japan); Onosaka, Satomi [Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180 (Japan)

    2005-04-01

    Metallothionein (MT) demonstrates strong antioxidant properties, yet the physiological relevance of its antioxidant action is not clear. Injection of mice with ferric nitrilotriacetate (Fe-NTA) caused a dose-dependent increase in hepatic and renal MT. Fe-NTA caused a greater increase in hepatic and renal MT concentration (2.5- and 4-fold) compared with FeCl{sub 3} at the same dose of ferric ion. MT mRNA levels were markedly elevated in both of tissues. Thiobarbituric acid (TBA) values in both tissues reached a maximum after 2-4 h. The MT concentrations were significantly increased after 2-4 h in liver and after 8-16 h in kidneys. Plasma concentrations of cytokines such as IL-6 and TNF{alpha} were elevated by 4 h; IL-6 levels were 24 times higher after Fe-NTA than that after injection of FeCl{sub 3}. Pretreatment of mice with ZnSO{sub 4} attenuated nephrotoxicity induced by Fe-NTA after 2 h, but was not effective 4 h after injection. After a Fe-NTA injection, a loss of Cd-binding properties of preinduced MT was observed only in kidneys of Zn-pretreated mice but not in liver. Treatment with BSO, glutathione (GSH) depletor, intensified a loss of its Cd-binding properties after a Fe-NTA injection. These results indicate that induction of MT synthesis may result from reactive oxygen species (ROS) generated by Fe-NTA, and MT may act in vivo as a complementary antioxidant.

  5. High-yield syntheses and reactivity studies of Fe10 "ferric wheels": structural, magnetic, and computational characterization of a star-shaped Fe8 complex.

    PubMed

    Stamatatos, Theocharis C; Christou, Alexander G; Mukherjee, Shreya; Poole, Katye M; Lampropoulos, Christos; Abboud, Khalil A; O'Brien, Ted A; Christou, George

    2008-10-01

    Convenient, high-yield routes have been developed to [Fe 10(OMe) 20(O 2CR) 10] ( 1) "ferric wheels" involving the alcoholysis of [Fe 3O(O 2CR) 6(H 2O) 3] (+) salts in MeOH in the presence of NEt 3. Reactivity studies have established [Fe 10(OMe) 20(O 2CMe) 10] ( 1a) to undergo clean carboxylate substitution with a variety of other RCO 2H groups to the corresponding [Fe 10(OMe) 20(O 2CR) 10] product. In contrast, the reaction with phenol causes a nuclearity change to give a smaller [Fe 8(OH) 4(OPh) 8(O 2CR) 12] ( 2) wheel. Similarly, reactions of [Fe 10(OMe) 20(O 2CR) 10] with the bidentate chelate ethylenediamine (en) cause a structural change to give either [Fe 8O 5(O 2CMe) 8(en) 8](ClO 4) 6 ( 3) or [Fe 2O(O 2CBu (t))(en) 4](NO 3) 3 ( 4), depending on conditions. Complex 3 possesses a "Christmas-star" Fe 8 topology comprising a central planar [Fe 4(mu 4-O)] (10+) square subunit edge-fused to four oxide-centered [Fe 3(mu 3-O)] (7+) triangular units. Variable-temperature, solid-state dc and ac magnetization studies on complexes 1a- 4 in the 5.0-300 K range established that all the complexes possess an S = 0 ground state. The magnetic susceptibility data for 4 were fit to the theoretical chi M versus T expression derived by the use of an isotropic Heisenberg spin Hamiltonian and the Van Vleck equation, and this revealed an antiferromagnetic exchange parameter with a value of J = -107.7(5) cm (-1). This value is consistent with that predicted by a previously published magnetostructural relationship. Theoretically computed values of the exchange constants in 3 were obtained with the ZILSH method, and the pattern of spin frustration within its core and the origin of its S = 0 ground state have been analyzed in detail. PMID:18698763

  6. Mineral and iron oxidation at low temperatures by pure and mixed cultures of acidophilic microorganisms.

    PubMed

    Dopson, Mark; Halinen, Anna-Kaisa; Rahunen, Nelli; Ozkaya, Bestamin; Sahinkaya, Erkan; Kaksonen, Anna H; Lindström, E Börje; Puhakka, Jaakko A

    2007-08-01

    An enrichment culture from a boreal sulfide mine environment containing a low-grade polymetallic ore was tested in column bioreactors for simulation of low temperature heap leaching. PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequencing revealed the enrichment culture contained an Acidithiobacillus ferrooxidans strain with high 16S rRNA gene similarity to the psychrotolerant strain SS3 and a mesophilic Leptospirillum ferrooxidans strain. As the mixed culture contained a strain that was within a clade with SS3, we used the SS3 pure culture to compare leaching rates with the At. ferrooxidans type strain in stirred tank reactors for mineral sulfide dissolution at various temperatures. The psychrotolerant strain SS3 catalyzed pyrite, pyrite/arsenopyrite, and chalcopyrite concentrate leaching. The rates were lower at 5 degrees C than at 30 degrees C, despite that all the available iron was in the oxidized form in the presence of At. ferrooxidans SS3. This suggests that although efficient At. ferrooxidans SS3 mediated biological oxidation of ferrous iron occurred, chemical oxidation of the sulfide minerals by ferric iron was rate limiting. In the column reactors, the leaching rates were much less affected by low temperatures than in the stirred tank reactors. A factor for the relatively high rates of mineral oxidation at 7 degrees C is that ferric iron remained in the soluble phase whereas, at 21 degrees C the ferric iron precipitated. Temperature gradient analysis of ferrous iron oxidation by this enrichment culture demonstrated two temperature optima for ferrous iron oxidation and that the mixed culture was capable of ferrous iron oxidation at 5 degrees C. PMID:17187443

  7. Influence of oxidizing or reducing agents on gastrointestinal absorption of U, Pu, Am, Cm and Pm by rats

    SciTech Connect

    Sullivan, M.F.; Ruemmler, P.S.; Ryan, J.L.; Buschbom, R.L.

    1986-02-01

    Absorption of 233U, 238Pu, 241Am, and 244Cm from the gastrointestinal (GI) tract was measured in rats, fed ad libitum or fasted, that were gavaged with solutions containing ferric iron, ferrous iron, iron powder, quinhydrone or ascorbic acid. Absorption and retention of all of these actinides was increased substantially by fasting and by the addition of mild oxidizing agents, ferric iron and quinhydrone. In contrast, absorption and retention were decreased to below the fasted level by all the reducing agents except ascorbic acid, which caused diarrhea and an increase in absorption. Absorption of the lanthanide element 147Pm from the intestine of fasted rats was also increased by ferric iron. Some of these actinide elements are polyvalent and are, in some cases, known to be absorbed from the GI tract more readily in their higher oxidation states. This suggested an oxidation-reduction mechanism for the effect of fasting and the action of the chemical agents used. However, the improbability that either 241Am(III) 244Cm(III) or 147Pm is converted to a different oxidation state under these conditions makes that mechanism unlikely. Other explanations are suggested.

  8. Influence of oxidizing or reducing agents on gastrointestinal absorption of U, Pu, Am, Cm and Pm by rats.

    PubMed

    Sullivan, M F; Ruemmler, P S; Ryan, J L; Buschbom, R L

    1986-02-01

    Absorption of 233U, 238Pu, 241Am, and 244Cm from the gastrointestinal (GI) tract was measured in rats, fed ad libitum or fasted, that were gavaged with solutions containing ferric iron, ferrous iron, iron powder, quinhydrone or ascorbic acid. Absorption and retention of all of these actinides was increased substantially by fasting and by the addition of mild oxidizing agents, ferric iron and quinhydrone. In contrast, absorption and retention were decreased to below the fasted level by all the reducing agents except ascorbic acid, which caused diarrhea and an increase in absorption. Absorption of the lanthanide element 147Pm from the intestine of fasted rats was also increased by ferric iron. Some of these actinide elements are polyvalent and are, in some cases, known to be absorbed from the GI tract more readily in their higher oxidation states. This suggested an oxidation-reduction mechanism for the effect of fasting and the action of the chemical agents used. However, the improbability that either 241Am(III) 244Cm(III) or 147Pm is converted to a different oxidation state under these conditions makes that mechanism unlikely. Other explanations are suggested. PMID:3005196

  9. The structural behavior of ferric and ferrous iron in aluminosilicate glass near meta-aluminosilicate joins

    Microsoft Academic Search

    Bjorn O. Mysen

    2006-01-01

    Iron-57 resonant absorption Mössbauer spectroscopy was used to describe the redox relations and structural roles of Fe3+ and Fe2+ in meta-aluminosilicate glasses. Melts were formed at 1500°C in equilibrium with air and quenched to glass in liquid H2O with quenching rates exceeding 200°C\\/s. The aluminosilicate compositions were NaAlSi2O6, Ca0.5AlSi2O6, and Mg0.5AlSi2O6. Iron oxide was added in the form of Fe2O3,

  10. The structural behavior of ferric and ferrous iron in aluminosilicate glass near meta-aluminosilicate joins

    NASA Astrophysics Data System (ADS)

    Mysen, Bjorn O.

    2006-05-01

    Iron-57 resonant absorption Mössbauer spectroscopy was used to describe the redox relations and structural roles of Fe 3+ and Fe 2+ in meta-aluminosilicate glasses. Melts were formed at 1500 °C in equilibrium with air and quenched to glass in liquid H 2O with quenching rates exceeding 200 °C/s. The aluminosilicate compositions were NaAlSi 2O 6, Ca 0.5AlSi 2O 6, and Mg 0.5AlSi 2O 6. Iron oxide was added in the form of Fe 2O 3, NaFeO 2, CaFe 2O 4, and MgFe 2O 4 with total iron oxide content in the range ˜0.9 to ˜5.6 mol% as Fe 2O 3. The Mössbauer spectra, which were deconvoluted by assuming Gaussian distributions of the hyperfine field, are consistent with one absorption doublet of Fe 2+ and one of Fe 3+. From the area ratios of the Fe 2+ and Fe 3+ absorption doublets, with corrections for differences in recoil-fractions of Fe 3+ and Fe 2+, the Fe 3+/?Fe is positively correlated with increasing total iron content and with decreasing ionization potential of the alkali and alkaline earth cation. There is a distribution of hyperfine parameters from the Mössbauer spectra of these glasses. The maximum in the isomer shift distribution function of Fe 3+, ?Fe 3+, ranges from about 0.25 to 0.49 mm/s (at 298 K relative to Fe metal) with the quadrupole splitting maximum, ?Fe 3+, ranging from ˜1.2 to ˜1.6 mm/s. Both ?Fe 3+ and ?Fe 2+ are negatively correlated with total iron oxide content and Fe 3+/?Fe. The dominant oxygen coordination number Fe 3+ changes from 4 to 6 with decreasing Fe 3+/?Fe. The distortion of the Fe 3+-O polyhedra of the quenched melts (glasses) decreases as the Fe 3+/?Fe increases. These polyhedra do, however, coexist with lesser proportions of polyhedra with different oxygen coordination numbers. The ?Fe 2+ and ?Fe 2+ distribution maxima at 298 K range from ˜0.95 to 1.15 mm/s and 1.9 to 2.0 mm/s, respectively, and decrease with increasing Fe 3+/?Fe. We suggest that these hyperfine parameter values for the most part are more consistent with Fe 2+ in a range of coordination states from 4- to 6-fold. The lower ?Fe 2+-values for the most oxidized melts are consistent with a larger proportion of Fe 2+ in 4-fold coordination compared with more reduced glasses and melts.

  11. The structural behavior of ferric and ferrous iron in aluminosilicate glass near meta-aluminosilicate joins

    Microsoft Academic Search

    Bjorn O. Mysen

    2006-01-01

    Iron-57 resonant absorption Mössbauer spectroscopy was used to describe the redox relations and structural roles of Fe3+ and Fe2+ in meta-aluminosilicate glasses. Melts were formed at 1500 °C in equilibrium with air and quenched to glass in liquid H2O with quenching rates exceeding 200 °C\\/s. The aluminosilicate compositions were NaAlSi2O6, Ca0.5AlSi2O6, and Mg0.5AlSi2O6. Iron oxide was added in the form

  12. Remote sensing of ferric iron minerals as guides for gold exploration

    NASA Technical Reports Server (NTRS)

    Taranik, Dan L.; Kruse, Fred A.; Goetz, Alexander F. H.; Atkinson, William W.

    1991-01-01

    The relationship between the surficial iron mineralogy and economic mineralization is investigated, using data from an airborne imaging spectrometer (the 63-channel Geophysical and Environmental Research Imaging Spectrometer) to map the distribution of iron minerals in the Cripple Creek mining district in Colorado. The airborne image data were coregistered with the field map data for the distribution of iron oxides in the district, in a geographic information computer system, in order to compare their information content. It is shown that the remote imagery was able to uniquely identify the mineral hematite, a mixture of goethite/jarosite, and a mixture of hematite/goethite.

  13. Enhanced hydrogen oxidation activity and H2S tolerance of Ni-infiltrated ceria solid oxide fuel cell anodes

    NASA Astrophysics Data System (ADS)

    Mirfakhraei, Behzad; Paulson, Scott; Thangadurai, Venkataraman; Birss, Viola

    2013-12-01

    The effect of Ni infiltration into porous Gd-doped ceria (GDC) anodes on their H2 oxidation performance, with and without added 10 ppm H2S, is reported here. Porous GDC anodes (ca. 10 ?m thick) were deposited on yttria stabilized zirconia (YSZ) supports and then infiltrated with catalytic amounts of a Ni nitrate solution, followed by electrochemical testing in a 3-electrode half-cell setup at 500-800 °C. Infiltration of 3 wt.% Ni into the porous GDC anode lowered the polarization resistance by up to 85%, affecting mainly the low frequency impedance arc. When exposed to 10 ppm H2S, the Ni-infiltrated anodes exhibited a ca. 5 times higher tolerance toward sulfur poisoning compared to GDC anodes alone, also showing excellent long-term stability in 10 ppm H2S. In the presence of H2S, it is proposed that Ni, likely distributed as a nanophase, helps to maintain a clean GDC surface at the Ni/GDC interface at which the H2 oxidation reaction takes place. In turn, the GDC will readily supply oxygen anions to the adjacent Ni surfaces, thus helping to remove adsorbed sulfur.

  14. A randomized controlled trial comparing intravenous ferric carboxymaltose with oral iron for treatment of iron deficiency anaemia of non-dialysis-dependent chronic kidney disease patients

    PubMed Central

    Qunibi, Wajeh Y.; Martinez, Carlos; Smith, Mark; Benjamin, Joseph; Mangione, Antoinette; Roger, Simon D.

    2011-01-01

    Background. Iron deficiency is a common cause of anaemia and hyporesponsiveness to erythropoiesis-stimulating agents (ESAs) in non-dialysis-dependent chronic kidney disease (ND-CKD) patients. Current intravenous iron agents cannot be administered in a single high dose because of adverse effects. Ferric carboxymaltose, a non-dextran parenteral iron preparation, can be rapidly administered in high doses. Methods. This open-label trial randomized 255 subjects with glomerular filtration rates ??45 mL/min/1.73 m2, haemoglobin ??11 g/dL, transferrin saturation ??25%, ferritin ??300 ng/mL, and stable ESA dose to either intravenous ferric carboxymaltose 1000 mg over 15 min (with up to two additional doses of 500 mg at 2-week intervals) or oral ferrous sulphate 325 mg thrice daily for a total of 195 mg elemental iron daily for 56 days. Results. In the modified intent-to-treat population, the proportion of subjects achieving a haemoglobin increase ??1 g/dL at any time was 60.4% with ferric carboxymaltose and 34.7% with oral iron (P < 0.001). At Day 42, mean increase in haemoglobin was 0.95 ± 1.12 vs 0.50 ± 1.23 g/dL (P = 0.005), mean increase in ferritin was 432 ± 189 ng/mL vs 18 ± 45 ng/mL (P < 0.001) and mean increase in transferrin saturation was 13.6 ± 11.9% vs 6.1 ± 8.1% (P < 0.001). Treatment-related adverse events were significantly fewer with ferric carboxymaltose than with oral iron (2.7% and 26.2%, respectively; P < 0.0001). Conclusions. We conclude that 1000 mg ferric carboxymaltose can be rapidly administered, is more effective and is better tolerated than oral iron for treatment of iron deficiency in ND-CKD patients. PMID:20929915

  15. Changes in Hawaiian palagonite FE mineralogy associated with thermal alteration: Implications for Mars

    NASA Technical Reports Server (NTRS)

    Bell, James F., III; Morris, Richard V.; Adams, John B.

    1993-01-01

    We have studied six Hawaiian palagonitic tephra samples (PH-1 through PH-6) from a site where a Mauna Loa lava flow has partially embayed a Mauna Kea cinder cone Tephra samples that were not affected by the lava flow (PH-5, PH-6) consist of partially palagonitized coarse-grained glassy Hawaiitic particles whose iron mineralogy is dominated by nanophase ferric oxide (np-Ox) and olivine. Samples closest to the lava flow (PH-1 through PH-4) have been strongly altered and their iron mineralogy is dominated by np-Ox, magnetite, and hematite. This suite of samples has many spectral similarities to Martian bright regions; thus, this localized thermal alteration event may be an analog to similar processes on Mars that lead to the production of small amounts of crystalline ferric oxides within a poorly-crystalline or amorphous palagonitic matrix.

  16. Reduction and Oxidation of the Active Site Iron in Tyrosine Hydroxylase: Kinetics and Specificity†

    PubMed Central

    Frantom, Patrick A.; Seravalli, Javier; Ragsdale, Stephen W.; Fitzpatrick, Paul F.

    2006-01-01

    Tyrosine hydroxylase (TyrH) is a pterin-dependent enzyme that catalyzes the hydroxylation of tyrosine to form dihydroxyphenylalanine. The oxidation state of the active site iron atom plays a central role in the regulation of the enzyme. The kinetics of reduction of ferric TyrH by several reductants were determined by anaerobic stopped-flow spectroscopy. Anaerobic rapid freeze–quench EPR confirmed that the change in the near-UV absorbance of TyrH upon adding reductant corresponded to iron reduction. Tetrahydrobiopterin reduces wild-type TyrH following a simple second-order mechanism with a rate constant of 2.8 ± 0.1 mM?1 s?1. 6-Methyltetrahydropterin reduces the ferric enzyme with a second-order rate constant of 6.1 ± 0.1 mM?1 s?1 and exhibits saturation kinetics. No EPR signal for a radical intermediate was detected. Ascorbate, glutathione, and 1,4-benzoquinone all reduce ferric TyrH, but much more slowly than tetrahydrobiopterin, suggesting that the pterin is a physiological reductant. E332A TyrH, which has an elevated Km for tetrahydropterin in the catalytic reaction, is reduced by tetrahydropterins with the same kinetic parameters as those of the wild-type enzyme, suggesting that BH4 does not bind in the catalytic conformation during the reduction. Oxidation of ferrous TyrH by molecular oxygen can be described as a single-step second-order reaction, with a rate constant of 210 mM?1 s?1. S40E TyrH, which mimics the phosphorylated state of the enzyme, has oxidation and reduction kinetics similar to those of the wild-type enzyme, suggesting that phosphorylation does not directly regulate the interconversion of the ferric and ferrous forms. PMID:16475826

  17. Ultrasound-enhanced copper removal by hydrous iron oxide adsorption

    SciTech Connect

    Campos, H.R. [Univ. de Tarapaca, Arica (Chile); Wheat, P.E. [Univ. of Northern Iowa, Cedar Falls, IA (United States). Dept. of Industrial Technology

    1996-12-31

    A model system to investigate ultrasound-enhanced removal of metallic ions from aqueous solution by hydrous ferric oxide (HFO) adsorption has been conducted. The experimental data indicate that ultrasonic treatment of pre-formed HFO flocs can lead to enhanced removal of metallic ions from aqueous solution and that the level of enhancement is strongly correlated with the solution pH. Ultrasonic treatment has been shown to be effective at lowering the final solution concentration of copper species in the pH range 7.5--9.5 at copper to iron molar concentration ratios of 10 and 30%.

  18. Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

    USGS Publications Warehouse

    Henneberry, Yumiko K.; Kraus, Tamara E.C.; Nico, Peter S.; Horwath, William R.

    2012-01-01

    The objective was to assess the interaction of Fe coprecipitated with dissolved organic matter (DOM) and its effect on Fe (hydr)oxide crystallinity and DOM retention under abiotic reducing conditions. A Fe-based coagulant was reacted with DOM from an agricultural drain and the resulting precipitate (floc) was exposed to S(-II) and Fe(II). Solution concentrations of Fe(II/III) and DOM were monitored, floc crystallinity was determined using X-ray diffraction, and the composition and distribution of functional groups were assessed using scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Results indicate coprecipitation of Fe(III) with DOM forms a non-crystalline floc that withstands crystallization regardless of change in pH, Fe:DOM ratio and type of reductant added. There was no evidence that exposure to reducing conditions led to release of DOM from the floc, indicating that coprecipitation with complex natural DOM in aquatic environments may stabilize Fe (hydr)oxides against crystallization upon reaction with reduced species and lead to long term sequestration of the DOM. STXM analysis identified spatially distinct regions with remarkable functional group purity, contrary to the model of DOM as a relatively uniform complex polymer lacking identifiable organic compounds. Polysaccharide-like OM was strongly and directly correlated with the presence of Fe but showed different Fe binding strength depending on the presence of carboxylic acid functional groups, whereas amide and aromatic functional groups were inversely correlated with Fe content.

  19. Iron oxide from a seasonally anoxic lake

    NASA Astrophysics Data System (ADS)

    Tipping, E.; Woof, C.; Cooke, D.

    1981-09-01

    The ferric oxide formed by oxidation of Fe(II) in Esthwaite Water, U.K., during the lake's seasonal thermal stratification and deep-water anoxia consists of amorphous particles which are approximately spherical or ellipsoidal, with diameters in the range 0.05-0.5 ?m. Concentrations in the lake are 1011-1012 particles per litre, corresponding to 3 mg l-1 Fe. Unlike iron oxides of similar chemical composition formed by oxidative mechanisms in soil-borne waters, the particles do not appear to be composed of small primary particles. This is possibly because in the lake they form slowly, at low supersaturation. The particles contain 30-40% by weight Fe. The carbon content is uncertain because of contamination but is in the range 4-18%. Humic carbon contributes at least 4-7% of the total weight. Other major elements present are P, N, Mn, Si, S. Ca and Mg, comprising between them up to 8% of the total weight. The particles are negatively charged probably because of adsorbed humic substances, and also phosphate and silicate. Their electrophoretic mobility-pH dependence is similar to those of synthetic iron oxides added to samples of surface Esthwaite Water. The calculated zeta potential is - 27 mV, which is sufficiently high to make flocculation slow under lake conditions. The low flocculation rate partially accounts for the formation of a well-defined peak of particulate iron in the water column of the lake.

  20. Oxidative stability of soybean oil in oleosomes as affected by pH and iron.

    PubMed

    Kapchie, Virginie N; Yao, Linxing; Hauck, Catherine C; Wang, Tong; Murphy, Patricia A

    2013-12-01

    The oxidative stability of oil in soybean oleosomes, isolated using the Enzyme-Assisted Aqueous Extraction Process (EAEP), was evaluated. The effects of ferric chloride, at two concentration levels (100 and 500 ?M), on lipid oxidation, was examined under pH 2 and 7. The peroxide value (PV) and thiobarbituric acid-reactive substance (TBARS) value of oil, in oleosome suspensions stored at 60 °C, were measured over a 12 day period. The presence of ferric chloride significantly (P<0.05) affected the oxidative stability of oil in the isolated oleosome, as measured by the PV and TBARS. Greater lipid oxidation occurred under an acidic pH. In the pH 7 samples, the positively charged transition metals were strongly attracted to the negatively charged droplets. However, the low ?-potential and the high creaming rate at this pH, may have limited the oxidation. Freezing, freeze-drying or heating of oleosomes have an insignificant impact on the oxidative stability of oil in isolated soybean oleosomes. Manufacturers should be cautious when adding oleosomes as ingredients in food systems containing transition metal ions. PMID:23870959