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1

Flame Synthesis of Nanophase Oxide Powders  

Microsoft Academic Search

For several years, we have been developing a process--called Chemical Vapor Condensation (CVC)--for the high rate production of nanophase ceramic powders. This method proved to be well-suited to the synthesis of non-oxide ceramics, such as SiC and Si3N4. More recently, we have been investigating the synthesis of oxide ceramics by a similar process, except for the replacement of the original

B. H. Kear; N. G. Glumac; Y.-J. Chen; G. Skandan

1997-01-01

2

Al/Al-oxide nanophase composites: Hardness and NMR Results  

NASA Astrophysics Data System (ADS)

Hardness and high temperature 27-Al NMR measurements of Al/Al-oxide nanophase composites produced by consolidation of nanoscale Al particles which have been passivated by exposure to air are reported. The Al/Al-oxide nanophase composite material produced has a low density, is electrically conducting and has a hardness much larger than that of metallic Al. High temperature NMR measurements show that the Al metal melts at the same temperature in all the samples, including a large-grained Al metal sample, independent of grain size and without a change in shape of the sample. The results here confirm previous thermal measurements which show that the Al metal melts without grain growth in these materials. On the other hand, the temperature for the onset of rapid atomic diffusion, as estimated from NMR line widths, shows a significant sample dependence. Heated samples exhibit a further factor of five increase in hardness and yet remain electrically conducting.

Suits, B. H.; Apte, P.

1998-03-01

3

Pigmenting agents in Martian soils - Inferences from spectral, Moessbauer, and magnetic properties of nanophase and other iron oxides in Hawaiian palagonitic soil PN-9  

NASA Astrophysics Data System (ADS)

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 Moessbauer 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. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.

Morris, Richard V.; Golden, D. C.; Bell, James F., III; Lauer, Howard V., Jr.; Adams, John B.

1993-10-01

4

Mossbauer Effect Study on Crystallites of Supported Ferric Oxide.  

National Technical Information Service (NTIS)

Crystallite size measurements and interaction with the support material of ferric oxide with silica gel and alumina have been studied using Mossbauer spectroscopy and x-ray diffraction techniques. No compound formation from reaction of the ferric oxide wi...

H. M. Gager M. C. Hobson

1969-01-01

5

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

SciTech Connect

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.

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

1990-10-01

6

Oxidation of Benzoins with Ferric (III) Nitrate Supported on Kieselguhr  

Microsoft Academic Search

Efficient and selective oxidation of benzoins to corresponding benzils with ferric(III) nitrate nonahydrate supported on kieselguhr reagent under heterogeneous conditions and reflux is described. The present oxidations are completed within 2 h with the yield between 85 and 95%. The main advantage of this oxidation is that the reaction time is much shorter as compared to the other reported ferric(III)

Guo-Qiang Wang; Changhe Zhang; Negin Vatanian; Ji-Dong Lou

2008-01-01

7

Total oxidation of methane over doped nanophase cerium oxides  

Microsoft Academic Search

The formation of solid solutions of cerium oxide with the oxides of calcium, manganese, or neodymium enhances the catalytic\\u000a activity of cerium oxide for the total oxidation of methane, whereas solid solutions with lead oxide showed an opposite effect.\\u000a Reasons for this are discussed in terms of oxygen vacancy concentrations and mobilities, local structure configurations, number\\u000a of oxidation states of

A. E. C. Palmqvist; E. M. Johansson; S. G. Jarasb; M. Muhammeda

1998-01-01

8

Role of nanophase oxides in short-term atmospheric corrosion of structural steels  

NASA Astrophysics Data System (ADS)

Systematic studies on the development of nanophase iron oxides in the corrosion products of carbon and weathering steel were performed to understand the role of nanophase oxides in short-term atmospheric corrosion. Similarities and/or differences between short-term and long-term atmospheric corrosion were established by studying carbon steel and weathering steel coupons exposed in mild marine environments for short-term and comparing it with previously established long-term data. Influence of substitutional elements, in particular chromium, in forming nanophase goethite was investigated. Crystallographic, magnetic and morphological properties of nanophase chromium substituted goethite have been characterized in order to understand the protective nature of chromium-substituted goethite in a naturally weathered steel surface. Spectroscopic investigation of the corrosion products of both carbon and weathering steel indicated that lepidocrocite and goethite were the predominant oxides to form following short-term exposures. The corrosion coatings were well layered for exposure times as early as 2 months. The layering was very similar to that observed on steel coupons exposed for more than 8 years. The outer layer was composed of lepidocrocite and occasionally goethite. The inner layer was mainly composed of nanophase goethite. The relative fraction of nanophase goethite was significantly higher in weathering steel compared to carbon steel at the end of six months of exposure. The data analysis also revealed that during the first two months of exposure weathering steel corrodes faster than carbon steel. However carbon steel corrodes more rapidly after 6 months of exposure. At the end of one year, the corrosion rate of carbon steel is higher than weathering steel. It is proposed that during the couple of months, nucleation of oxides is the dominant process in both carbon and weathering steel. At the end of six months, a considerable amount of nanophase goethite formed on carbon steel continues to grow into bigger crystals. On the other hand, in weathering steel the crystal growth of a significant fraction of initially formed nanophase goethite is inhibited. It is proposed that substitutional elements like chromium inhibit the crystal growth in weathering steel. The crystallographic and spectroscopic data for showed that with increasing chromium concentration, the crystallite size of synthetic goethite measured from X-ray diffraction and particle length of goethite measured from Mossbauer spectroscopy and Transmission Electron Microscopy, became smaller. (Abstract shortened by UMI.)

Balasubramanian, Rama

9

Small angle neutron scattering from nanophase titanium as a function of oxidation  

SciTech Connect

Nanophase titanium, prepared by the gas-condensation method both as aggregated powder and in lightly compacted discs, has been studied by conventional small angle neutron scattering, and by use of contrast variation methods. The contrast has been changed (a) isotopically, by means of deuterated/protonated solvents distilled into the specimen and (b) by progressive incremental oxidation of the Ti particles using fixed doses of low-pressure oxygen. It was shown that some evolution of the small angle pattern for lightly compacted nanophase Ti occurred over a period of several months at 300 K. Contrast matching by external solvent works well and has allowed the scattering lengths of oxidized and unoxidized specimens to be followed. The results imply that the scattering from metal and oxide can be separated under suitable conditions. The partial oxidation experiments indicate that there is both a fast and slow oxidation at 300 K. Also, during slow oxidation, high scattering length density scattering centers were formed whose number increased, but whose size remained the same at about 2 nm; these centers are tentatively assumed to be TiO/sub 2/. 5 refs., 3 figs., 1 tab.

Eastman, J.A.; Epperson, J.E.; Hahn, H.; Klippert, T.E.; Narayanasamy, A.; Ramasamy, S.; Siegel, R.W.; White, J.W.; Trouw, F.

1989-02-01

10

NMR study and hardness behavior of nanophase Al/Al-oxide consolidated composite  

NASA Astrophysics Data System (ADS)

Over the past few years, nanostructured materials (grain sizes 1-100 nm) have generated a lot of interest in the scientific community. This interest has mainly stemmed from the reported superior properties of these materials over conventional ones and their potential for commercial applications. A variety of techniques including SEM, TEM, PAS, etc. have been used to study nanophase materials. This work reports the study of a nanophase composite material using the non-destructive NMR spectroscopic technique. The composite studied is a nanophase Al/Al-Oxide system with the Al metal in the grains and the Al-Oxide in the grain boundaries. The production of such a nanoscale Al/Al-Oxide powder is described. Hardness, mass density and electrical conductivity measurements on the pellets formed by the consolidation of this powder at different consolidation pressures is reported. NMR studies of this composite material are reported at room temperature. The design and construction of a high temperature NMR probe is described. Limited high temperature NMR measurements are then described. Hardness measurements conducted on the samples indicate an increase in hardness with decrease in grain size in accordance with the Hall-Petch relationship. Interestingly, some of the samples were electrically conducting and some non-conducting. An increase in hardness with an insignificant change in mass density was observed in some samples. High temperature NMR results indicate the melting of the Al metal within the oxide at or around the melting point of aluminum (660sp°C). X-Ray measurements show no evidence of grain growth with increase in temperature. Both the X-Ray and NMR measurements show a substantial increase in the aluminum-oxide content of the samples after heating. NMR measurements performed on the samples before and after heating show a non-reversible behavior of the samples upon heating with respect to their signal intensity. Hardness tests performed on the samples after heating them indicate an increase in hardness by as much as a factor of five as compared to the hardness of the unheated samples. In conclusion, the experiments have successfully demonstrated the synthesis of a unique nanophase low density, high strength composite material capable of retaining its superior properties even above the melting point of aluminum.

Apte, Palash Prakash

11

Oxidation dynamics of nanophase aluminum clusters : a molecular dynamics study.  

SciTech Connect

Oxidation of an aluminum nanocluster (252,158 atoms) of radius 100{angstrom} placed in gaseous oxygen (530,727 atoms) is investigated by performing molecular-dynamics simulations on parallel computers. The simulation takes into account the effect of charge transfer between Al and O based on the electronegativity equalization principles. We find that the oxidation starts at the surface of the cluster and the oxide layer grows to a thickness of {approximately}28{angstrom}. Evolutions of local temperature and densities of Al and O are investigated. The surface oxide melts because of the high temperature resulting from the release of energy associated with Al-O bondings. Amorphous surface-oxides are obtained by quenching the cluster. Vibrational density-of-states for the surface oxide is analyzed through comparisons with those for crystalline Al, Al nanocluster, and {alpha}-Al{sub 2}O{sub 3}.

Ogata, S.

1998-01-27

12

21 CFR 186.1300 - Ferric oxide.  

Code of Federal Regulations, 2013 CFR

...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...

2013-04-01

13

Nanophase Manganese Oxides: Chemisorbed Water and Small Particle Size Promote Large Thermodynamically Driven Shifts in Oxidation-Reduction Equilibria  

NASA Astrophysics Data System (ADS)

Manganese oxides are important in terrestrial and Martian settings, and changes in oxidation state (Mn 2+, 3+, 4+) produce different phases. This study focuses on changes in redox energetics at the nanoscale in the Mn-O system with water present. Nanophase hausmannite (Mn3O4), bixbyite (Mn2O3), and pyrolusite (MnO2) were synthesized using minor modifications of previously published methods, stored at room temperature, and then analyzed by powder-XRD, BET surface area measurement, and TGA for total water content. High-temperature oxide-melt drop solution calorimetry was performed on a series of characterized samples with known surface area and water content. The differential heat of water adsorption as a function of coverage was also measured. The surface enthalpies of manganese oxide phases, hausmannite (Mn3O4), bixbyite (Mn2O3), and pyrolusite (MnO2), were determined using the data from high-temperature oxide melt calorimetry and water adsorption calorimetry. Surface energy for the hydrous Mn3O4 tetragonal spinel phase is 0.96±0.08 J/m2, for Mn2O3 cubic phase is 1.29±0.10 J/m2, and for MnO2 cubic rutile phase is 1.64±0.10 J/m2. Surface energy for the anhydrous Mn3O4 is 1.31±0.08 J/m2, for Mn2O3 is 1.57±0.10 J/m2, and for MnO2 is 1.99±0.10 J/m2. Supporting preliminary findings, the spinel phase (hausmannite) has a lower surface energy than bixbyite, while the latter has a smaller surface energy than pyrolusite. We also observed phase changes, some of them rapidly reversible, associated with water adsorption/desorption for the nanophase manganese oxide assemblages. There are geochemical consequences. (1) At the nanoscale, both the pyrolusite/bixbyite and bixbyite/hausmannite equilibria are shifted to higher oxygen fugacity because the reduced phase has the lower surface energy. (2) The ready inter-conversion of phases with different oxidation states under aqueous conditions implies that, after a manganese oxide nanophase forms, it can easily transform to other phases with different oxidation states and water contents and perhaps record changes in environmental conditions after, as well as during, its initial formation.

Birkner, N.; Navrotsky, A.

2011-12-01

14

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

Microsoft Academic Search

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

Surjit Singh Bhatti; Kanwar Jit Singh

2003-01-01

15

Location of nanophase Fe-oxides in palagonitic soils: Implication for Martian pigments  

NASA Astrophysics Data System (ADS)

Palagonitic materials from Mauna Kea, Hawaii, were identified as Mars analogs based on their spectral and magnetic properties. These materials probably resulted from hydrothermal alteration during eruption of the volcano and/or from weathering under ambient conditions. The reflectance spectra of the Mars surface obtained by Earth-based telescopes and the reflectance spectra of analogs obtained in the laboratory show features due to electronic transitions of Fe(III) in oxide particles that range in size from nanometer (nanophase) to micrometer sized or larger. The presence of Fe(III) suggests oxidizing conditions during the alteration process in Mars that may have occurred in the past or during a slow ongoing process. Two naturally altered basaltic samples from Hawaii (HWMK12 and HWMK13) and a laboratory-altered (PH-13-DCGT2) basaltic glass similar in elemental composition to the above two samples was examined. All three samples exhibited spectral characteristics similar to martian bright-region spectra. Chemical and mineralogical changes occurring at the surface of these basalts were studied in order to understand the basis for their Mars-like properties. The spectral properties of the three samples were examined after the removal of Fe oxides by chemical extractants.

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

1993-09-01

16

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

NASA Astrophysics Data System (ADS)

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 and softening temperatures. Structural changes involve boron anomaly, field strengths of cations, difference in ionic radii, and charge state of iron. Makishima-Mackenzie (theoretical model) and IR and NGR techniques confirm the conclusions arrived at. The network modifier (NWM) is varied from 25 to 45 mol% for manganese oxide borate and from 15 to 40 mol% with 10 mol% doping of ferric oxide. For zinc oxide borate glasses, it varies from 26 to 34 mol% and with 10 mol% of ferric oxide, its variation is from 15 to 35 mol%. Impact of doping by ferric oxide on the properties of these glass systems have been investigated.

Bhatti, Surjit Singh; Singh, Kanwar Jit

2003-04-01

17

Small Angle Neutron Scattering from Nanophase Titanium as a Function of Oxidation.  

National Technical Information Service (NTIS)

Nanophase titanium, prepared by the gas-condensation method both as aggregated powder and in lightly compacted discs, has been studied by conventional small angle neutron scattering, and by use of contrast variation methods. The contrast has been changed ...

J. A. Eastman J. E. Epperson H. Hahn T. E. Klippert A. Narayanasamy

1989-01-01

18

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

PubMed

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

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

2013-08-26

19

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

PubMed Central

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.

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

2013-01-01

20

Dietary bioavailability of Cu adsorbed to colloidal hydrous ferric oxide.  

PubMed

The dietary bioavailability of copper (Cu) adsorbed to synthetic colloidal hydrous ferric oxide (HFO) was evaluated from the assimilation of (65)Cu by two benthic grazers, a gastropod and a larval mayfly. HFO was synthesized, labeled with (65)Cu 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 (65)Cu concentrations ranging from 211 to 2204 nmol/g (dry weight). Animals were pulse fed the contaminated diet and assimilation of (65)Cu from HFO was determined following 1-3 days of depuration. Mass transfer of (65)Cu from HFO to the diatom was less than 1%, indicating that HFO was the source of (65)Cu 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. PMID:23402601

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

2013-02-26

21

Ultraviolet Magneto-Optics of Opaque Magnetic Media: Ferric Oxide Compounds.  

National Technical Information Service (NTIS)

The first observations of uv optical and magneto-optical spectra for bulk, single-crystal ferric oxide compounds are reported. Measurements were made on rare earth orthoferrites, rare earth iron garnets, nickel ferrite, and ferrimagnetic magneto-plumbite....

F. J. Kahn

1969-01-01

22

Role of Ferric Oxide Surface Area in Propellant Burn Rate Enhancement (First Step Toward Modeling).  

National Technical Information Service (NTIS)

Results of efforts to correlate composite propellant burn rate, ammonium perchlorate particle size distribution, and ferric oxide specific surface and level are presented. Results from laboratory-scale motor firings with HTPB- and CTPB-based propellants c...

C. H. Burnside

1975-01-01

23

Oxygen isotope fractionation in ferric oxide-water systems: low temperature synthesis  

Microsoft Academic Search

The magnitude and temperature-sensitivity of oxygen isotope fractionation in ferric oxide-water systems remain uncertain. In this study, three different synthetic methods are used to investigate the temperature dependence of the fractionation between water and hematite, akaganeite, and goethite at near-surface temperatures. Our results reveal two similarities among these ferric oxide-water systems. First, the fractionation of oxygen isotopes between water and

Huiming Bao; PAUL L. KOCH

1999-01-01

24

Selective Oxidation of Benzoins to Benzils with Ferric (III) Nitrate Supported on Graphite Reagent  

Microsoft Academic Search

Selective oxidation of benzoins into corresponding benzils using ferric (III) nitrate nonahydrate supported on graphite reagent under heterogeneous conditions and reflux is described. The present oxidations are completed within 3 hours with the yield between 82–95%. It has the main advantage of being readily available, inexpensive, and relatively non?toxic oxidation reagent.

Feng Li; Li Li

2007-01-01

25

Prooxidant and antioxidant effects of trolox on ferric ion-induced oxidation of erythrocyte membrane lipids  

Microsoft Academic Search

The prooxidant and antioxidant actions of Trolox were examined in anin vitro system measuring ferric ion-induced oxidation of erythrocyte membrane lipids. Trolox was found to produce a concentration-dependent biphasic effect on the ferric ion-stimulated lipid peroxidation, with the mode of action being similar to those produced by reducing-agent antioxidants, such as ascorbic acid and reduced glutathione, and iron chelator, such

Kam Ming Ko; Pak Kin Yick; Michael K. T. Poon; Siu Po Ip

1994-01-01

26

Study on the Burning Characteristics of AP\\/Al\\/HTPB Composite Solid Propellant Containing Nano-Sized Ferric Oxide Powder  

Microsoft Academic Search

This study mainly explores the burning characteristics of AP\\/Al\\/HTPB composite solid propellant containing nano-sized ferric oxide (Fe2O3) powder. Firstly, the appropriate dispersed technique is applied to prepare the propellant samples containing the ferric oxide (micro-sized and\\/or nano-sized) powder and then the scanning electron microscope (SEM) is used to observe the dispersed effect of ferric oxide powder in the propellant samples.

Kai-Tai Lu; Tsung-Mao Yang; Jin-Shuh Li; Tsao-Fa Yeh

2012-01-01

27

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

28

The mechanism of selenate adsorption on goethite and hydrous ferric oxide  

Microsoft Academic Search

Sorption of anions on mineral surfaces, and specifically on Fe oxides, is a topic of continued interest in soil and environmental chemistry. EXAFS spectroscopy has been used to investigate the structure of selenate surface complexes sorbed on dry and wet goethite and hydrous ferric oxide. It is shown that selenate oxyanions always form inner-sphere surface complexes on both sorbents regardless

A. Manceau; L. Charlet

1994-01-01

29

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

PubMed

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 Mn(3+)/Mn(4+) 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

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

2013-05-10

30

Nanophase transition metal oxides show large thermodynamically driven shifts in oxidation-reduction equilibria.  

PubMed

Knowing the thermodynamic stability of transition metal oxide nanoparticles is important for understanding and controlling their role in a variety of industrial and environmental systems. Using calorimetric data on surface energies for cobalt, iron, manganese, and nickel oxide systems, we show that surface energy strongly influences their redox equilibria and phase stability. Spinels (M(3)O(4)) commonly have lower surface energies than metals (M), rocksalt oxides (MO), and trivalent oxides (M(2)O(3)) of the same metal; thus, the contraction of the stability field of the divalent oxide and expansion of the spinel field appear to be general phenomena. Using tabulated thermodynamic data for bulk phases to calculate redox phase equilibria at the nanoscale can lead to errors of several orders of magnitude in oxygen fugacity and of 100 to 200 kelvin in temperature. PMID:20929770

Navrotsky, Alexandra; Ma, Chengcheng; Lilova, Kristina; Birkner, Nancy

2010-10-01

31

Ultraviolet Magneto-Optical Properties of Single-Crystal Ferrimagnetic Ferric Oxide Compounds.  

National Technical Information Service (NTIS)

The first uv measurements of the complex polar-Kerr effect (rotation and ellipticity) are reported between 1.7 and 5.64 eV for representative ferrimagnetic ferric oxide compounds containing both octahedral (Fe(oct)) and tetrahedral (Fe(tet)) sites. Room-t...

F. J. Kahn P. S. Pershan J. P. Remeika

1969-01-01

32

Ultraviolet Magneto-Optical Properties of Single-Crystal Orthoferrites, Garnets, and Other Ferric Oxide Compounds.  

National Technical Information Service (NTIS)

The ultraviolet and visible linear magneto-optical properties of representative ferric oxide compounds were measured by reflection methods between 1.7 and 5.64 eV at room temperature. The experimental technique, based on the complex polar Kerr effect (rot...

F. J. Kahn P. S. Pershan J. P. Remeika

1969-01-01

33

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...

34

Aqueous pyrite oxidation by dissolved oxygen and by ferric iron  

Microsoft Academic Search

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

Carl O. Moses; D. Kirk Nordstrom; Janet S. Herman; Aaron L. Mills

1987-01-01

35

In situ monitoring magnetism and resistance of nanophase platinum upon electrochemical oxidation.  

PubMed

Controlled tuning of material properties by external stimuli represents one of the major topics of current research in the field of functional materials. Electrochemically induced property tuning has recently emerged as a promising pathway in this direction making use of nanophase materials with a high fraction of electrode-electrolyte interfaces. The present letter reports on electrochemical property tuning of porous nanocrystalline Pt. Deeper insight into the underlying processes could be gained by means of a direct comparison of the charge-induced response of two different properties, namely electrical resistance and magnetic moment. For this purpose, four-point resistance measurements and SQUID magnetometry were performed under identical in situ electrochemical control focussing on the regime of electrooxidation. Fully reversible variations of the electrical resistance and the magnetic moment of 6% and 1% were observed upon the formation or dissolution of a subatomic chemisorbed oxygen surface layer, respectively. The increase of the resistance, which is directly correlated to the amount of deposited oxygen, is considered to be primarily caused by charge-carrier scattering processes at the metal-electrolyte interfaces. In comparison, the decrease of the magnetic moment upon positive charging appears to be governed by the electric field at the nanocrystallite-electrolyte interfaces due to spin-orbit coupling. PMID:23844345

Steyskal, Eva-Maria; Topolovec, Stefan; Landgraf, Stephan; Krenn, Heinz; Würschum, Roland

2013-06-24

36

In situ monitoring magnetism and resistance of nanophase platinum upon electrochemical oxidation  

PubMed Central

Summary Controlled tuning of material properties by external stimuli represents one of the major topics of current research in the field of functional materials. Electrochemically induced property tuning has recently emerged as a promising pathway in this direction making use of nanophase materials with a high fraction of electrode-electrolyte interfaces. The present letter reports on electrochemical property tuning of porous nanocrystalline Pt. Deeper insight into the underlying processes could be gained by means of a direct comparison of the charge-induced response of two different properties, namely electrical resistance and magnetic moment. For this purpose, four-point resistance measurements and SQUID magnetometry were performed under identical in situ electrochemical control focussing on the regime of electrooxidation. Fully reversible variations of the electrical resistance and the magnetic moment of 6% and 1% were observed upon the formation or dissolution of a subatomic chemisorbed oxygen surface layer, respectively. The increase of the resistance, which is directly correlated to the amount of deposited oxygen, is considered to be primarily caused by charge-carrier scattering processes at the metal–electrolyte interfaces. In comparison, the decrease of the magnetic moment upon positive charging appears to be governed by the electric field at the nanocrystallite–electrolyte interfaces due to spin–orbit coupling.

Steyskal, Eva-Maria; Topolovec, Stefan; Landgraf, Stephan; Krenn, Heinz

2013-01-01

37

Aqueous pyrite oxidation by dissolved oxygen and by ferric iron  

NASA Astrophysics Data System (ADS)

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 increases in sulfoxy anions and (3) thiosulfate and polythionates at pH > 3.9. Intermediate sulfoxy anions were observed only at high stirring rates. In anaerobic Fe(III)-saturated solutions, no intermediates were observed except traces of sulfite at pH 9. The faster rate of oxidation in Fe(III)-saturated solutions supports a reaction mechanism in which Fe(III) is the direct oxidant of pyrite in both aerobic and anaerobic systems. The proposal of this mechanism is also supported by theoretical considerations regarding the low probability of a direct reaction between paramagnetic molecular oxygen and diamagnetic pyrite. Results from a study of sphalerite oxidation support the hypothesis that thiosulfate is a key intermediate in sulfate production, regardless of the bonding structure of the sulfide mineral.

Moses, Carl O.; Nordstrom, D. Kirk; Herman, Janet S.; Mills, Aaron L.

1987-06-01

38

Aqueous pyrite oxidation by dissolved oxygen and by ferric iron  

SciTech Connect

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 increases in sulfoxy anions, and (3) thiosulfate and polythionates at pH > 3.9 Intermediate sulfoxy anions were observed only at high stirring rates. In anaerobic Fe(III)-saturated solutions, no intermediates were observed except traces of sulfite at pH 9. The faster rate of oxidation in Fe(III)-saturated solutions supports a reaction mechanism in which Fe(III) is the direct oxidant of pyrite in both aerobic and anaerobic systems. The proposal of this mechanism is also supported by theoretical considerations regarding the low probability of a direct reaction between paramagnetic molecular oxygen and diamagnetic pyrite. Results from a study of sphalerite oxidation support the hypothesis that thiosulfate is a key intermediate in sulfate production, regardless of the bonding structure of the sulfide mineral.

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

1987-06-01

39

Ultraviolet Magneto-Optical Properties of Single-Crystal Orthoferrites, Garnets, and Other Ferric Oxide Compounds  

Microsoft Academic Search

The ultraviolet and visible linear magneto-optical properties of representative ferric oxide compounds were measured by reflection methods between 1.7 and 5.64 eV at room temperature. The experimental technique, based on the complex polar Kerr effect (rotation and ellipticity), was applied to all available single-crystal rare-earth orthoferrites and to representative rare-earth iron garnets, nickel spinel ferrite, and magnetoplumbite. For representative orthoferrites

Frederic J. Kahn; P. S. Pershan; J. P. Remeika

1969-01-01

40

Stoichiometry of bacterial anaerobic oxidation of elemental sulfur by ferric iron.  

PubMed

The conventional stoichiometry of the oxidation of elemental sulfur by ferric iron in Acidithiobacillus ferrooxidans was not in agreement with our experimental data in terms of ferrous iron and proton formation. Reaction modelling under the actual conditions of bacterial activity resulted in a different stoichiometry, where additional iron species participate in the process to affect the number of released protons. The suggested reaction equation may more accurately predict the intensity of environmental acidification during the anaerobic bioprocess. PMID:22249244

Kucera, Jiri; Zeman, Josef; Mandl, Martin; Cerna, Hana

2012-01-17

41

Effect of Intravenous Saccharated Ferric Oxide on Serum FGF23 and Mineral Metabolism in Hemodialysis Patients  

Microsoft Academic Search

Background\\/Aims: Fibroblast growth factor-23 (FGF23) plays a central role in the development of hypophosphatemia and inappropriately low 1,25-dihydroxyvitamin D induced by iron therapy for iron-deficiency anemia. The aim of this study was to examine the effect of intravenous saccharated ferric oxide on serum FGF23 levels and mineral metabolism in hemodialysis patients. Methods: This prospective study enrolled 27 hemodialysis patients who

Yoko Takeda; Hirotaka Komaba; Shunsuke Goto; Hideki Fujii; Michio Umezu; Hirohito Hasegawa; Akira Fujimori; Masato Nishioka; Shinichi Nishi; Masafumi Fukagawa

2011-01-01

42

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

NASA Astrophysics Data System (ADS)

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.

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

43

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

Microsoft Academic Search

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

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

2008-01-01

44

Comparative study of pulmonary responses to nano- and submicron-sized ferric oxide in rats  

Microsoft Academic Search

Ferric oxide (Fe2O3) nanoparticles are of considerable interest for application in nanotechnology related fields. However, as iron being a highly redox-active transition metal, the safety of iron nanomaterials need to be further studied. In this study, the size, dose and time dependent of Fe2O3 nanoparticle on pulmonary and coagulation system have been studied after intratracheal instillation. The Fe2O3 nanoparticles with

Mo-Tao Zhu; Wei-Yue Feng; Bing Wang; Tian-Cheng Wang; Yi-Qun Gu; Meng Wang; Yun Wang; Hong Ouyang; Yu-Liang Zhao; Zhi-Fang Chai

2008-01-01

45

A combined treatment of landfill leachate using calcium oxide, ferric chloride and clinoptilolite.  

PubMed

The aim of this research was development of appropriate procedure for treatment of landfill leachate taken from old sanitary landfill Piskornica (Koprivnica, Croatia). Due to complex nature of the effluent a combined treatment approach was applied. Samples were treated with calcium oxide followed by ferric chloride and finally with clinoptilolite. The optimum amount of treating agents and contact time were determined. Application of calcium oxide (25 g/L, 20 min. contact time) resulted in the reduction of color, turbidity, suspended solids and ammonia for 94.50%, 96.55%, 95.66% and 21.60%, respectively, while the removal efficiency of Cr (VI), Fe, Ni, Cu, Zn and Pb was 75.00%, 95.34%, 56.52%, 78.72%, 73.02% and 100.00%, respectively. After addition of ferric chloride (570 mg Fe(3+)/L, 20 min. contact time) removal efficiency of color, turbidity, suspended solids and ammonia increased to 96.04%, 99.27%, 98.61%, and 43.20%, respectively. Removal of ammonia (81.60%) increased significantly after final adsorption onto clinoptilolite (25 g/L, 4 h contact time). Removal of COD after successive treatment with calcium oxide, ferric chloride and clinoptilolite was 64.70%, 77.40% and 81.00%, respectively. PMID:21308604

Orescanin, Visnja; Ruk, Damir; Kollar, Robert; Mikelic, Ivanka Lovrencic; Nad, Karlo; Mikulic, Nenad

2011-01-01

46

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

PubMed Central

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

Lazaroff, Norman; Sigal, Warren; Wasserman, Andrew

1982-01-01

47

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

NASA Astrophysics Data System (ADS)

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.

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

2006-03-01

48

Enhanced electrochemical oxidation of phenol by introducing ferric ions and UV radiation.  

PubMed

The mineralization of phenol in aerated electrochemical oxidation has been investigated. The results show that a cathodic Fenton process can occur when the Ti-0.3Mo-0.8Ni alloy material is used as cathode in solution containing ferric or ferrous ions; moreover, the reinforcement of cathodic Fenton process on the total organic carbon (TOC) removal rate of phenol is quite distinct. Among the metallic ions investigated, the ferric ion is the best catalyst for the electrochemical mineralization of phenol at initial pH 2.0, and the optimal concentration range is from 50 to 200 mg/L. The favorable pH range and supporting electrolyte (Na2SO4) concentration for mineralization of phenol in solution containing ferrous ions are 1.8-2.3 and below 0.10 mol/L, respectively. UV radiation can improve the TOC removal rate of phenol, but the enhanced effect varies in different solutions. In the solution containing ferric ions, an equal sum or synergetic effect can be observed. The optimal effect of electrolysis system under UV radiation is achieved in the solution containing 50 mg/L Fe3+ with a final removal percentage of 81.3%. PMID:19202880

Mao, Xuhui; Wei, Lin; Hong, Song; Zhu, Hua; Lin, An; Gan, Fuxing

2008-01-01

49

The mechanism of selenate adsorption on goethite and hydrous ferric oxide  

SciTech Connect

Sorption of anions on mineral surfaces, and specifically on Fe oxides, is a topic of continued interest in soil and environmental chemistry. EXAFS spectroscopy has been used to investigate the structure of selenate surface complexes sorbed on dry and wet goethite and hydrous ferric oxide. It is shown that selenate oxyanions always form inner-sphere surface complexes on both sorbents regardless of the hydration state. Selenate, like phosphate and selenite, forms binuclear bridging complexes on (hk0) planes with two singly coordinated A-type OH groups. Furthermore evidence is provided for the attachment of selenate oxyanions on (001) planes by the sharing of edges with Fe octahedra. Selenite and arsenate appear to form the same types of surface complexes as selenate at the surface of goethite and hydrous ferric oxide. It is likely that this sorption mechanism is operative for other anions including phosphate and sulfate. A consequence of this study is the conclusion that the crystallographic planes of Fe oxides (hk0 and 001) do not appear to selectivity bond either cations or anions, at least at high surface coverage.

Manceau, A.; Charlet, L. (Univ. of Grenoble (France). Environmental Geochemistry Group)

1994-11-01

50

Kinetic measurement of biological oxidation of ferrous iron at low ferric to ferrous ratios in a controlled potential batch reactor  

Microsoft Academic Search

Traditionally, the kinetics of microbial ferrous iron oxidation have been studied in continuous or in batch culture. Both methods have drawbacks: in continuous culture experiments have to be repeated at a number of dilution rates to cover the entire spectrum of ferrous to ferric ratios, which is time-consuming. Furthermore, experiments at very low ferric-to-ferrous ratios require high dilution rates which

Thierry Kamunga Kazadi; Jochen Petersen

2008-01-01

51

The oxidation of carbonate green rust into ferric phases:solid-state reaction or transformation via solution  

NASA Astrophysics Data System (ADS)

The oxidation of carbonate green rust, GR(CO 32-), in NaHCO 3 solutions at T = 25°C has been investigated through electrochemical techniques, FTIR, XRD, TEM and SEM. The used GR(CO 32-) samples were made of either suspended solid in solution or a thin electrochemically formed layer on the surface of an iron disc. Depending on experimental conditions, oxidation occurs, with or without major modifications of the GR(CO 32-) structure, suggesting the existence of two pathways: solid-state oxidation (SSO) leading to a ferric oxyhydroxycarbonate as the end product, and a dissolution-oxidation-precipitation (DOP) mechanism leading to ferric oxihydroxides such as lepidocrocite, goethite, or ferrihydrite. A formula was proposed for this ferric oxyhydroxycarbonate, Fe 6IIIO (2+x)(OH) (12-2x)(H 2O) x(CO 3), assuming that the solid-state oxidation reaction is associated to a deprotonation of the water molecules within the interlayers, or of the hydroxyl groups in the Fe(O,H) octahedra layers. The DOP mechanism involves transformation via solution with the occurrence of soluble ferrous-ferric intermediate species. A discussion about factors influencing the oxidation of carbonate green rust is provided hereafter. The ferric oxyhydroxycarbonate can be reduced back to GR(CO 32-) by a reverse solid-state reduction reaction. The potentiality for a solid-state redox cycling of iron to occur may be considered. The stability of the ferric oxyhydroxycarbonate towards thermodynamically stable ferric phases, such as goethite and hematite, was also studied.

Legrand, Ludovic; Mazerolles, Léo; Chaussé, Annie

2004-09-01

52

The fate of iron on Mars: Mechanism of oxidation of basaltic minerals to ferric-bearing assemblages  

NASA Astrophysics Data System (ADS)

Perhaps the most conspicuous indication that chemical weathering has occurred on the surface of Mars is the overall color of the red planet and the spectroscopic features that identify ferric-bearing assemblages in the martian regolith. Apparently, Fe(2+) ions in primary minerals in parent igneous rocks on the martian surface have been oxidized to ferric iron, which occurs in degradation products that now constitute the regolith. The mineralogy of the unweathered igneous rocks prior to weathering on the martian surface is reasonably well constrained, mainly as a result of petrographic studies of the SNC meteorites. However, the alteration products resulting from oxidative weathering of these rocks are less well-constrained. The topics covered include the following: primary rocks subjected to chemical weathering; dissolution processes; oxidation of dissolved Fe(2+); mechanism of polymerization of hydrous ferric oxides; terrestrial occurrences of ferromagnesian smectites; and dehydroxylated Mg-Fe smectites on Mars.

Burns, Roger G.

1993-09-01

53

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

PubMed Central

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.

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

2010-01-01

54

Uranium Extraction From Laboratory Synthesized, Uranium-Doped Hydrous Ferric Oxides  

SciTech Connect

The extractability of uranium (U) from synthetic hydrous ferric oxides has been shown to decrease as a function of mineral ripening, consistent with the hypothesis that the ripening process decrease contaminant lability. To evaluate this process, three hydrous ferric oxide (HFO) suspensions were co-precipitated with uranyl (UO22+) and maintained at pH 7.0 ± 0.1. Uranyl was added to the HFO post-precipitation in a fourth suspension. Two suspensions also contained either co-precipitated silicate (Si-U-HFO) or phosphate (P-U-HFO). After precipitation of the HFOs, at time intervals of one week, one month, six months, one year, and 2 years, aliquots of the suspensions were contacted with five solutions for a range of time. The extracts were analyzed for U and iron (Fe). The results are consistent with the hypothesis that U and Fe extractability will decrease as the mineral phase ripens. All extracting solutions exhibited some degree of selectivity for U, as the proportional extraction of U exceeded that for congruent dissolution. Micro X-ray diffraction analysis indicates the transformation from an amorphous phase to a material containing substantial proportions of crystalline goethite and hematite, except the P-U-HFO which remained primarily amorphous. Further analysis of the co-precipitates by the Mössbauer technique and scanning electron microscopy (SEM) provides further evidence of mineralogic ripening

Smith, Steven C.; Douglas, Matthew; Moore, Dean A.; Kukkadapu, Ravi K.; Arey, Bruce W.

2009-03-01

55

Synthesis and characterization of reduced transition metal oxides and nanophase metals with hydrazine in aqueous solution  

Microsoft Academic Search

Reduction of the first row (3d) transition metal complexes in aqueous solution using hydrazine as the reducing agent has been investigated systematically. Nanoscale reduced metal oxides such as VO2(B), Cr2O3 were obtained through hydrazine reduction followed by proper thermal treatments. Nanocrystalline ?-Mn2O3 was synthesized directly through aqueous phase reduction at room temperature. Nanoclusters of cobalt, copper and the one-dimensional single

Zhou Gui; Rong Fan; Weiqin Mo; Xianhui Chen; Ling Yang; Yuan Hu

2003-01-01

56

Reduction of Soluble Iron and Reductive Dissolution of Ferric Iron-Containing Minerals by Moderately Thermophilic Iron-Oxidizing Bacteria  

Microsoft Academic Search

Five moderately thermophilic iron-oxidizing bacteria, including representative strains of the three classified species (Sulfobacillus thermosulfidooxidans, Sulfobacillus acidophilus, and Acidimicrobium ferrooxidans), were shown to be capable of reducing ferric iron to ferrous iron when they were grown under oxygen limitation conditions. Iron reduction was most readily observed when the isolates were grown as mixotrophs or hetero- trophs with glycerol as an

TONI A. M. BRIDGE; D. BARRIE JOHNSON

1998-01-01

57

Ni(II) Complexation to Amorphous Hydrous Ferric Oxide: An X-ray Absorption Spectroscopy Study  

SciTech Connect

Ni(II) sorption onto iron oxides and in particular hydrous ferric oxide (HFO) is among the important processes impacting its distribution, mobility, and bioavailability in environment. To develop mechanistic models for Ni, extended X-ray absorption fine structure (EXAFS) analysis has been conducted on Ni(II) sorbed to HFO. Coprecipitation revealed the formation of the metastable {alpha}-Ni(OH){sub 2} at a Ni(II) loading of 3.5 x 10{sup -3} mol g{sup -1}. On the other hand, Ni(II) formed inner-sphere mononuclear bidentate complexes along edges of FeO{sub 6} octahedra when sorbed to HFO surfaces with Ni-O distances of 2.05-2.07 {angstrom} and Ni-Fe distances of 3.07-3.11 {angstrom}. This surface complex was observed by EXAFS study over 2.8 x 10{sup -3} to 10{sup -1} ionic strength, pH from 6 to 7, a Ni(II) loading of 8 x 10{sup -4} to 8.1 x 10{sup 03} mol g{sup -1} HFO, and reaction times from 4 hours to 8 months. The short- and long-range structure analyses suggest that the presence of Ni(II) inhibited transformation of the amorphous iron oxide into a more crystalline form. However, Ni{sup 2+} was not observed to substitute for Fe{sup 3+} in the oxide structure. This study systematically addresses Ni(II) adsorption mechanisms to amorphous iron oxide. The experimentally defined surface complexes can be used to constrain surface complexation modeling for improved prediction of metal distribution at the iron oxide/aqueous interface.

Xu,Y.; Axe, L.; Boonfueng, T.; Tyson, T.; Trivedi, P.; Pandya, K.

2007-01-01

58

Geminate rebinding dynamics of nitric oxide to ferric hemoglobin in D2O solution.  

PubMed

Femtosecond mid-infrared (mid-IR) spectroscopy was used to probe geminate rebinding (GR) dynamics of photo-released nitric oxide (NO) to ferric hemoglobin (Hb(III)) in D2O solution at room temperature. Time-resolved vibrational spectra exhibit two overlapping NO bands for NO-bound Hb(III) (Hb(III)NO), a major band at 1925 cm(-1) (89%) and a minor one at 1905 cm(-1) (11%), suggesting that Hb(III)NO has at least two conformational substates. Both bands decay nonexponentially, each with a different time scale, and the decays are described by a stretched exponential function; the major band's decay is described by 0.96 exp(-t/40 ps)(0.86) + 0.04 and the minor band's decay is described by exp(-t/85 ps)(0.75). These decays arise mainly from the GR of the photo-released NO to Hb(III), indicating that the bound state's conformer influences the NO binding. In particular, the His64 residue, known to have inward conformation in the major band and outward conformation in the minor band, plays a significant role in controlling the binding of NO to Hb(III). The GR of NO to ferric Hb is slower than that to ferrous Hb, which shows fast and efficient GR due to the high reactivity of NO to the heme Fe(ii). The slower GR of NO to Hb(III) may be caused by the lower reactivity of NO to the heme Fe(iii). PMID:23512239

Park, Jaeheung; Lee, Taegon; Lim, Manho

2013-03-20

59

Redox Reactions of Phenazine Antibiotics with Ferric (Hydr)oxides and Molecular Oxygen  

PubMed Central

Phenazines are small redox-active molecules produced by a variety of bacteria. Beyond merely serving as antibiotics, recent studies suggest that phenazines play important physiological roles, including one in iron acquisition. Here we characterize the ability of four electrochemically reduced natural phenazines—pyocyanin (PYO), phenazine-1-carboxylate (PCA), phenazine-1-carboxamide, and 1-hydroxyphenazine (1-OHPHZ)—to reductively dissolve ferrihydrite and hematite in the pH range 5–8. Generally, the reaction rate is higher for a phenazine with a lower reduction potential, with the reaction between PYO and ferrihydrite at pH 5 being an exception; the rate decreases as the pH increases; the rate is higher for poorly crystalline ferrihydrite than for highly crystalline hematite. Ferric (hydr)oxide reduction by reduced phenazines can potentially be inhibited by oxygen, where O2 competes with Fe(III) as the final oxidant. The reactivity of reduced phenazines with O2 decreases in the order: PYO > 1-OHPHZ > PCA. Strikingly, reduced PYO, which is the least reactive phenazine with ferrihydrite and hematite at pH 7, is the most reactive phenazine with O2. These results imply that different phenazines may perform different functions in environments with gradients of iron and O2.

Wang, Yun; Newman, Dianne K.

2009-01-01

60

Reactivity of ferric oxides toward H2S at low pH.  

PubMed

Goethite (gt), 2-line (21fh), 6-line ferrihydrite (61fh), and schwertmannite (shm) were reacted with H2S under steady-state conditions at pH 2.5-5 using a novel setup that consisted of an electrochemical sulfide generator transporting H2S into a suspension of oxides in a fluidized bed-reactor. The reactants were stoichiometrically converted into Fe2+ and So. Sulfate significantly inhibited the rates. Surface area normalized rates increased with pH. They depended on the mineral type following the order gt > 21fh > 61fh, contrasting previous observations at circumneutral pH with an inverse order. The rate of shm dissolution was highest probably due to direct reduction of dissolved ferric iron by H2S. A linear relationship between the observed rate and the surface species of H2S was derived from a surface complexation approach that allowed for the estimation of intrinsic rate constants kintr for the various oxides (38 min(-1), 1.4 min(-1), 0.29 min(-1) for gt, 21fh, and 61fh, respectively). kint decreased with increasing deltaGf for the reactions and seems to depend on the reduction potential of the solution. From this observation we derived the hypothesis that kint is determined by the flat-band potential of the mineral/solute interface at low pH while being affected by surface interactions at higher pH. PMID:17539520

Peiffer, Stefan; Gade, Winfried

2007-05-01

61

Redox reactions of phenazine antibiotics with ferric (hydr)oxides and molecular oxygen.  

PubMed

Phenazines are small redox-active molecules produced by a variety of bacteria. Beyond merely serving as antibiotics, recent studies suggest that phenazines play important physiological roles, including one in iron acquisition. Here we characterize the ability of four electrochemically reduced natural phenazines--pyocyanin (PYO), phenazine-1-carboxylate (PCA), phenazine-1-carboxamide, and 1-hydroxyphenazine (1-OHPHZ)--to reductively dissolve ferrihydrite and hematite in the pH range 5-8. Generally, the reaction rate is higher for a phenazine with a lower reduction potential, with the reaction between PYO and ferrihydrite at pH 5 being an exception; the rate decreases as the pH increases; the rate is higher for poorly crystalline ferrihydrite than for highly crystalline hematite. Ferric (hydr)oxide reduction by reduced phenazines can potentially be inhibited by oxygen, where O2 competes with Fe(III) as the final oxidant The reactivity of reduced phenazines with 02 decreases in the order: PYO > 1-OHPHZ > PCA. Strikingly, reduced PYO,which isthe least reactive phenazine with ferrihydrite and hematite at pH 7, is the most reactive phenazine with O2. These results imply that different phenazines may perform different functions in environments with gradients of iron and O2. PMID:18504969

Wang, Yun; Newman, Dianne K

2008-04-01

62

Stable iron isotope fractionation between aqueous Fe(II) and hydrous ferric oxide.  

PubMed

Despite the ubiquity of poorly crystalline ferric hydrous oxides (HFO, or ferrihydrite) in natural environments, stable Fe isotopic fractionation between HFO and other Fe phases remains unclear. In particular, it has been difficult to determine equilibrium Fe isotope fractionation between aqueous Fe(II) and HFO due to fast transformation of the latter to more stable minerals. Here we used HFO stabilized by the presence of dissolved silica (2.14 mM), or a Si-HFO coprecipitate, to determine an equilibrium Fe(II)-HFO fractionation factor using a three-isotope method. Iron isotope exchange between Fe(II) and HFO was rapid and near complete with the Si-HFO coprecipitate, and rapid but incomplete for HFO in the presence of dissolved silica, the latter case likely reflecting blockage of oxide surface sites by sorbed silica. Equilibrium Fe(II)-HFO (56)Fe/(54)Fe fractionation factors of -3.17 ± 0.08 (2?)‰ and -2.58 ± 0.14 (2?)‰ were obtained for HFO plus silica and the Si-HFO coprecipitate, respectively. Structural similarity between ferrihydrite and hematite, as suggested by spectroscopic studies, combined with the minor isotopic effect of dissolved silica, imply that the true equilibrium Fe(II)-HFO (56)Fe/(54)Fe fractionation factor in the absence of silica may be ?-3.2‰. These results provide a critical interpretive context for inferring the stable isotope effects of Fe redox cycling in nature. PMID:21294566

Wu, Lingling; Beard, Brian L; Roden, Eric E; Johnson, Clark M

2011-02-04

63

Biotransformation of Ni-substituted hydrous ferric oxide by an Fe(III)-reducing bacterium.  

PubMed

The reductive biotransformation of a Ni(2+)-substituted (5 mol %) hydrous ferric oxide (NiHFO) by Shewanella putrefaciens, strain CN32, was investigated under anoxic conditions at circumneutral pH. Our objectives were to define the influence of Ni2+ substitution on the bioreducibility of the HFO and the biomineralization products formed and to identify biogeochemical factors controlling the phase distribution of Ni2+ during bioreduction. Incubations with CN32 and NiHFO were sampled after 14 and 32 d, and both aqueous chemistry and solid phases were characterized. By comparison of these results with a previous study (Fredrickson, J. K.; Zachara, J. M.; Kennedy, D. W.; Dong, H.; Onstott, T. C.; Hinman, N. W.; Li, S. W. Geochim. Cosmochim. Acta 1998, 62, 3239-3257), it was concluded that coprecipitated/sorbed Ni2+ inhibited the bioreduction of HFO through an undefined chemical mechanism. Mössbauer spectroscopy allowed analysis of the residual HFO phase and the identity and approximate mass percent of biogenic mineral phases. The presence of AQDS, a soluble electron shuttle that obviates need for cell--oxide contact, was found to counteract the inhibiting effect of Ni2+. Nickel was generally mobilized during bioreduction in a trend that correlated with final pH, except in cases where PO4(3-) was present and vivianite precipitation occurred. CN32 promoted the formation of Ni(2+)-substituted magnetite (Fe2IIIFe(1-x)IINixIIO4) in media with AQDS but without PO4(3-). The formation of this biogenic coprecipitate, however, had little discernible impact on final aqueous Ni2+ concentrations. These results demonstrate that coprecipitated Ni can inhibit dissimilatory microbial reduction of amorphous iron oxide, but the presence of humic acids may facilitate the immobilization of Ni within the crystal structure of biogenic magnetite. PMID:11349281

Fredrickson, J K; Zachara, J M; Kukkadapu, R K; Gorby, Y A; Smith, S C; Brown, C F

2001-02-15

64

Removal of arsenite and arsenate using hydrous ferric oxide incorporated into naturally occurring porous diatomite.  

PubMed

In this study, a simplified and effective method was tried to immobilize iron oxide onto a naturally occurring porous diatomite. Experimental resultsfor several physicochemical properties and arsenic edges revealed that iron oxide incorporated into diatomite was amorphous hydrous ferric oxide (HFO). Sorption trends of Fe (25%)-diatomite for both arsenite and arsenate were similar to those of HFO, reported by Dixit and Hering (Environ. Sci. Technol. 2003, 37, 4182-4189). The pH at which arsenite and arsenate are equally sorbed was 7.5, which corresponds to the value reported for HFO. Judging from the number of moles of iron incorporated into diatomite, the arsenic sorption capacities of Fe (25%)-diatomite were comparable to or higher than those of the reference HFO. Furthermore, the surface complexation modeling showed that the constants of [triple bond]SHAsO4- or [triple bond]SAsO4(2-) species for Fe (25%)-diatomite were larger than those reference values for HFO or goethite. Larger differences in constants of arsenate surface species might be attributed to aluminum hydroxyl ([triple bond]Al-OH) groups that can work better for arsenate removal. The pH-controlled differential column batch reactor (DCBR) and small-scale column tests demonstrated that Fe (25%)-diatomite had high sorption speeds and high sorption capacities compared to those of a conventional sorbent (AAFS-50) that is known to be the first preference for arsenic removal performance in Bangladesh. These results could be explained by the fact that Fe (25%)-diatomite contained well-dispersed HFO having a great affinity for arsenic species and well-developed macropores as shown by scanning electron microscopy (SEM) and pore size distribution (PSD) analyses. PMID:16568781

Jang, Min; Min, Soo-Hong; Kim, Tak-Hyun; Park, Jae Kwang

2006-03-01

65

Tumor Promotion and Oxidative Stress in Ferric Nitrilotriacetate-Mediated Renal Carcinogenesis: Protection by Adhatoda vasica.  

PubMed

ABSTRACT In the present study, we report the chemopreventive effects of Adhatoda vasica against ferric nitrilotriacetate (Fe-NTA)-induced renal oxidative stress, hyperproliferative response, and two-stage renal carcinogenesis. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances renal lipid peroxidation, xanthine oxidase (XO), and hydrogen peroxide (H(2)O(2)) generation with concomitant reduction in renal glutathione content (GSH), antioxidant enzymes, and phase II metabolizing enzymes. It induces blood urea nitrogen, serum creatinine, ornithine decarboxylase (ODC) activity, and [(3)H] thymidine incorporation into renal DNA. It also enhances DEN (N-diethylnitrosamine)-initiated renal carcinogenesis by increasing the percentage incidences of kidney tumors. Pretreatment of rats orally with A. vasica (50 and 100 mg/kg body weight) resulted in a significant decrease in lipid peroxidation, H(2)O(2) generation, xanthine oxidase (XO), blood urea nitrogen, serum creatinine, renal ODC activity, DNA synthesis (p < 0.001), and incidence of tumors. Renal GSH (p < 0.01), glutathione-metabolizing enzymes (p < 0.001), and antioxidant enzymes were also recovered significantly (p < 0.001). Thus, our results show that A. vasica may meet the criteria demanded from a chemopreventive agent and in a rodent system it can reduce hyperproliferative response toxicity and carcinogenic activity of Fe-NTA. PMID:20020945

Jahangir, Tamanna; Sultana, Sarwat

2007-01-01

66

Arsenic desorption from ferric and manganese binary oxide by competitive anions: significance of pH.  

PubMed

Ferric and manganese binary oxide (FMBO) has been used to remediate an arsenic (As)-polluted river in China, but insufficient data was available to (1) evaluate its effects on the environment and (2) propose a feasible strategy of addressing the arsenic-bearing FMBO. The desorption behavior of arsenic in the presence of four competitive anions (i.e., phosphate, silicate, sulfate, and bicarbonate) at different concentrations was investigated with pH ranging from 3 to 11. The presence of these anions promoted the desorption of arsenic from arsenic-bearing FMBO and followed the sequence of phosphate > silicate > sulfate approximately equal to bicarbonate across a wide pH range. Desorption of arsenate (As[V]) was more significant than that of arsenite (As[III]). Sequence dissolution of arsenic-bearing FMBO particles by NH4-oxalate/oxalic acid and hydrochloric acid were performed. The laboratory results indicated that As(III) was primarily occluded in the crystalline parts of the FMBO. The desorption behavior of arsenic could be described by kinetic models using the Elovich and power function equations under different pH conditions and was related to the adsorption of phosphate and silicate. pH played an important role in the desorption of arsenic, because of its effects on the species distribution of anions, surface charge of the arsenic-bearing FMBO, and subsequent electrostatic forces between anions and FMBO. PMID:22866393

Xu, Wei; Wang, Hongjie; Wu, Kun; Liu, Ruiping; Gong, Wenxin; Qu, Jiuhui

2012-06-01

67

Induction of renal oxidative stress and cell proliferation response by ferric nitrilotriacetate (Fe-NTA): diminution by soy isoflavones  

Microsoft Academic Search

Ferric nitrilotriacetate (Fe-NTA) is a known potent nephrotoxic agent. In this communication, we report the chemopreventive effect of soy isoflavones on renal oxidative stress, toxicity and cell proliferation response in Wistar rats. Fe-NTA (9mg Fe\\/kg body weight, intraperitoneally) enhances ?-glutamyl transpeptidase, renal lipid peroxidation, xanthine oxidase and hydrogen peroxide (H2O2) generation with reduction in renal glutathione content, antioxidant enzymes, viz.,

Naghma Khan; Sarwat Sultana

2004-01-01

68

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

Microsoft Academic Search

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

Jennifer A Wilkie; Janet G Hering

1996-01-01

69

Effects of ferric iron reduction and regeneration on nitrous oxide and methane emissions in a rice soil  

Microsoft Academic Search

A laboratory soil slurry experiment and an outdoor pot experiment were conducted to study effects of ferric iron (Fe(III)) reduction and regeneration on nitrous oxide (N2O) and methane (CH4) emissions in a rice (Oryza sativa L.) soil. The anoxic slurry experiment showed that enhancing microbial Fe(III) reduction by ferrihydrite amendment (40mol Feg?1) transitionally stimulated N2O production and lowered CH4 production

Bin Huang; Kewei Yu; Robert P. Gambrell

2009-01-01

70

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

NASA Astrophysics Data System (ADS)

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 explained the kinetics of dissolution of pyrite. The dissolution of pyrite is an oxidation-reduction reaction. The kinetics of the oxidation and reduction half-reactions was studied independently using electrochemical techniques of voltammetry. The kinetics of the overall reaction was studied by the electrochemical technique of potentiometry, which consisted of measuring the mixed potential of a sample of corroding pyrite in solutions of different compositions. The kinetics of the half reactions are related to the kinetics of the overall dissolution reaction by the condition that there is no accumulation of charge. This principle is used to derive expressions for the mixed potential and the rate of dissolution, which successfully describe the mixed potential measurements and the kinetics of dissolution reported in the literature. It is shown that the observations of half-order kinetics and that the oxygen in the sulphate product arises from water are both a direct consequence of the electrochemical mechanism. Thus it is concluded that the electrochemical reaction steps occurring at the mineral-solution interface control the rate of dissolution. Raman spectroscopy was used to analyze reaction products formed on the pyrite surface. The results indicated that small amounts of polysulphides form on the surface of the pyrite. However, it was also found that the mixed (corrosion) potential does not change over a 14-day leaching period. This indicates that even though polysulphide material is present on the surface, it does not influence the rate of the reactions occurring at the surface. Measurements of the sulphur yields as a function of electrode potential indicate that thiosulphate is not the only source of the sulphur product.

Holmes, Paul R.; Crundwell, Frank K.

2000-01-01

71

Comparative study of pulmonary responses to nano- and submicron-sized ferric oxide in rats.  

PubMed

Ferric oxide (Fe(2)O(3)) nanoparticles are of considerable interest for application in nanotechnology related fields. However, as iron being a highly redox-active transition metal, the safety of iron nanomaterials need to be further studied. In this study, the size, dose and time dependent of Fe(2)O(3) nanoparticle on pulmonary and coagulation system have been studied after intratracheal instillation. The Fe(2)O(3) nanoparticles with mean diameters of 22 and 280 nm, respectively, were intratracheally instilled to male Sprague Dawley rats at low (0.8 mg/kgbw) and high (20 mg/kgbw) doses. The toxic effects were monitored in the post-instilled 1, 7 and 30 days. Our results showed that the Fe(2)O(3) nanoparticle exposure could induce oxidative stress in lung. Alveolar macrophage (AM) over-loading of phagocytosed nanoparticle by high dose treatment had occurred, while the non-phagocytosed particles were found entering into alveolar epithelial in day 1 after exposure. Several inflammatory reactions including inflammatory and immune cells increase, clinical pathological changes: follicular hyperplasia, protein effusion, pulmonary capillary vessel hyperaemia and alveolar lipoproteinosis in lung were observed. The sustain burden of particles in AM and epithelium cells has caused lung emphysema and pro-sign of lung fibrosis. At the post-instilled day 30, the typical coagulation parameters, prothrombin time (PT) and activated partial thromboplastin time (APTT) in blood of low dose 22 nm-Fe(2)O(3) treated rats were significantly longer than the controls. We concluded that both of the two-sized Fe(2)O(3) particle intratracheal exposure could induce lung injury. Comparing with the submicron-sized Fe(2)O(3) particle, the nano-sized Fe(2)O(3) particle may increase microvascular permeability and cell lysis in lung epitheliums and disturb blood coagulation parameters significantly. PMID:18394769

Zhu, Mo-Tao; Feng, Wei-Yue; Wang, Bing; Wang, Tian-Cheng; Gu, Yi-Qun; Wang, Meng; Wang, Yun; Ouyang, Hong; Zhao, Yu-Liang; Chai, Zhi-Fang

2008-02-29

72

Synthesis, characterisation and ferric ion complexation studies of chelating probes for oxidative stress  

Microsoft Academic Search

The ferric ion binding characteristics of a novel chelating probe for detecting ‘reactive oxygen and nitrogen species’ are reported. The probe comprises a polyaminocarboxylic acid chelator (EDTA) conjugated with aromatic amino acids. The probe (i) complexes redox-active and non-redox active metal ions and (ii) differentiates between different reactive oxygen\\/nitrogen species based upon the reaction products with same. The ferric ion

Anna E. O. Fisher; Declan P. Naughton

2004-01-01

73

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

NASA Astrophysics Data System (ADS)

Dissimilatory iron-reducing bacteria (DIRB) couple the oxidation of organic matter or H 2 to the reduction of iron oxides. The factors controlling the rate and extent of these reduction reactions and the resulting solid phases are complex and poorly understood. Batch experiments were conducted with amorphous hydrous ferric oxide (HFO) and the DIRB Shewanella putrefaciens , strain CN32, in well-defined aqueous solutions to investigate the reduction of HFO and formation of biogenic Fe(II) minerals. Lactate-HFO solutions buffered with either bicarbonate or 1,4-piperazinediethanesulfonic acid (PIPES) containing various combinations of phosphate and anthraquinone-2,6-disulfonate (AQDS), were inoculated with S. putrefaciens CN32. AQDS, a humic acid analog that can be reduced to dihydroanthraquinone by CN32, was included because of its ability to function as an electron shuttle during microbial iron reduction and as an indicator of pe. Iron reduction was measured with time, and the resulting solids were analyzed by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). In HCO 3 - buffered medium with AQDS, HFO was rapidly and extensively reduced, and the resulting solids were dominated by ferrous carbonate (siderite). Ferrous phosphate (vivianite) was also present in HCO 3 - medium containing P, and fine-grained magnetite was present as a minor phase in HCO 3 - medium with or without P. In the PIPES-buffered medium, the rate and extent of reduction was strongly influenced by AQDS and P. With AQDS, HFO was rapidly converted to highly crystalline magnetite whereas in its absence, magnetite mineralization was slower and the final material less crystalline. In PIPES with both P and AQDS, a green rust type compound [Fe (6-x) II Fe x III (OH) 12 ] x+ [(A 2- ) x/2 · yH 2 O] x- was the dominant solid phase formed; in the absence of AQDS a poorly crystalline product was observed. The measured pe and nature of the solids identified were consistent with thermodynamic considerations. The composition of aqueous media in which microbial iron reduction occurred strongly impacted the rate and extent of iron reduction and the nature of the reduced solids. This, in turn, can provide a feedback control mechanism on microbial metabolism. Hence, in sediments where geochemical conditions promote magnetite formation, two-thirds of the Fe(III) will be sequestered in a form that may not be available for anaerobic bacterial respiration.

Fredrickson, James K.; Zachara, John M.; Kennedy, David W.; Dong, Hailang; Onstott, Tullis C.; Hinman, Nancy W.; Li, Shu-Mei

1998-10-01

74

Surface complexation modeling of Cu(II) adsorption on mixtures of hydrous ferric oxide and kaolinite  

PubMed Central

Background The application of surface complexation models (SCMs) to natural sediments and soils is hindered by a lack of consistent models and data for large suites of metals and minerals of interest. Furthermore, the surface complexation approach has mostly been developed and tested for single solid systems. Few studies have extended the SCM approach to systems containing multiple solids. Results Cu adsorption was measured on pure hydrous ferric oxide (HFO), pure kaolinite (from two sources) and in systems containing mixtures of HFO and kaolinite over a wide range of pH, ionic strength, sorbate/sorbent ratios and, for the mixed solid systems, using a range of kaolinite/HFO ratios. Cu adsorption data measured for the HFO and kaolinite systems was used to derive diffuse layer surface complexation models (DLMs) describing Cu adsorption. Cu adsorption on HFO is reasonably well described using a 1-site or 2-site DLM. Adsorption of Cu on kaolinite could be described using a simple 1-site DLM with formation of a monodentate Cu complex on a variable charge surface site. However, for consistency with models derived for weaker sorbing cations, a 2-site DLM with a variable charge and a permanent charge site was also developed. Conclusion Component additivity predictions of speciation in mixed mineral systems based on DLM parameters derived for the pure mineral systems were in good agreement with measured data. Discrepancies between the model predictions and measured data were similar to those observed for the calibrated pure mineral systems. The results suggest that quantifying specific interactions between HFO and kaolinite in speciation models may not be necessary. However, before the component additivity approach can be applied to natural sediments and soils, the effects of aging must be further studied and methods must be developed to estimate reactive surface areas of solid constituents in natural samples.

Lund, Tracy J; Koretsky, Carla M; Landry, Christopher J; Schaller, Melinda S; Das, Soumya

2008-01-01

75

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

Microsoft Academic Search

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

Paul R. Holmes; Frank K. Crundwell

2000-01-01

76

agr;Tocopherol (vitaminE) ameliorates ferric nitrilotriacetate (Fe-NTA)-dependent renal proliferative response and toxicity: diminution of oxidative stress  

Microsoft Academic Search

Ferric nitrilotriacetate (Fe-NTA) is a potent nephrotoxic agent. In this communication, we show the modulatory effect of DL-a-tocopherol (Vitamin-E) on ferric nitrilotriacetate (Fe-NTA)-induced renal oxidative stress, toxicity and hyperproliferative response in rats. Fe-NTA-treatment enhances the susceptibility of renal microsomal membrane for iron-ascorbate-induced lipid peroxidation and hydrogen peroxide generation which are accompanied by a decrease in the activities of renal antioxidant

Mohammad Iqbal; Hassan Rezazadeh; Sabah Ansar; Mohammad Athar

1998-01-01

77

Characterization of the pores in hydrous ferric oxide aggregates formed by freezing and thawing.  

PubMed

Hydrous ferric oxides (HFO) are efficient sorbents for inorganic and organic pollutants and therefore have great potentials in environmental science and engineering applications. Freezing and thawing of HFO suspensions leads to the formation of dense HFO aggregates. It facilitates the handling and increases the drying rate of HFO. In this study, we used a combination of pycnometry, gas adsorption (N(2) gas, water vapor), and small-angle neutron scattering (SANS) to characterize the porosity and pore size distribution of dense HFO aggregates formed by freezing dialyzed HFO suspensions at -25 degrees C and thawing them at room temperature. The crystallinity of the HFO, which was a 2-line ferrihydrite, was not affected by this treatment. Wet sieving and laser diffraction analysis showed that the dense HFO aggregates had a unimodal size distribution with an average diameter of 235+/-35 microm. Increasing the freezing rate by cooling with liquid N(2) (-196 degrees C) resulted in much smaller aggregates with an average diameter of 20 microm. Adding NaNO(3) electrolyte to the HFO suspensions prior to freezing also resulted in the formation of smaller aggregates. The dense HFO aggregates formed at -25 degrees C had a porosity of 0.73+/-0.02 ll(-1). SANS revealed a unimodal size distribution of pores, with an average pore diameter of 2.0 nm. The diameter of the HFO crystallites was estimated by transmission electron microscopy to be 1.9+/-0.5 nm. Geometrical considerations taking into account the unit particle and average pore size suggest that the crystallites retain 1-2 layers of hydration water during the coagulation induced by freezing. Analysis by N(2) gas adsorption showed that drying the dense HFO aggregates induced a reduction in porosity by about 25% and shifted the pore size distribution to smaller diameters. Rewetting during water vapor adsorption did not induce significant changes of the aggregate structure. The specific surface area of the dry HFO aggregates was between 320 and 380 m(2)g(-1). PMID:14757090

Hofmann, Annette; Pelletier, Manuel; Michot, Laurent; Stradner, Anna; Schurtenberger, Peter; Kretzschmar, Ruben

2004-03-01

78

Kinetics of anaerobic elemental sulfur oxidation by ferric iron in Acidithiobacillus ferrooxidans and protein identification by comparative 2-DE-MS/MS.  

PubMed

Elemental sulfur oxidation by ferric iron in Acidithiobacillus ferrooxidans was investigated. The apparent Michaelis constant for ferric iron was 18.6 mM. An absence of anaerobic ferric iron reduction ability was observed in bacteria maintained on elemental sulfur for an extended period of time. Upon transition from ferrous iron to elemental sulfur medium, the cells exhibited similar kinetic characteristics of ferric iron reduction under anaerobic conditions to those of cells that were originally maintained on ferrous iron. Nevertheless, a total loss of anaerobic ferric iron reduction ability after the sixth passage in elemental sulfur medium was demonstrated. The first proteomic screening of total cell lysates of anaerobically incubated bacteria resulted in the detection of 1599 protein spots in the master two-dimensional electrophoresis gel. A set of 59 more abundant and 49 less abundant protein spots that changed their protein abundances in an anaerobiosis-dependent manner was identified and compared to iron- and sulfur-grown cells, respectively. Proteomic analysis detected a significant increase in abundance under anoxic conditions of electron transporters, such as rusticyanin and cytochrome c(552), involved in the ferrous iron oxidation pathway. Therefore we suggest the incorporation of rus-operon encoded proteins in the anaerobic respiration pathway. Two sulfur metabolism proteins were identified, pyridine nucleotide-disulfide oxidoreductase and sulfide-quinone reductase. The important transcription regulator, ferric uptake regulation protein, was anaerobically more abundant. The anaerobic expression of several proteins involved in cell envelope formation indicated a gradual adaptation to elemental sulfur oxidation. PMID:22057833

Kucera, Jiri; Bouchal, Pavel; Cerna, Hana; Potesil, David; Janiczek, Oldrich; Zdrahal, Zbynek; Mandl, Martin

2011-11-05

79

Formation of ‘ferric green rust’ and\\/or ferrihydrite by fast oxidation of iron(II–III) hydroxychloride green rust  

Microsoft Academic Search

Fast oxidation processes of iron(II–III) hydroxychloride green rust GR(Cl?), FeII3FeIII(OH)8Cl·2H2O, were simulated by two different methods. The first one consisted in using a strong oxidiser, namely H2O2. The main end product, analysed by X-ray diffraction and Mössbauer spectroscopy, is an iron(III) compound, designated as “ferric GR(Cl?)”, characterised by a layered structure identical to that of normal GR(Cl?). The second method

Ph. Refait; O. Benali; M. Abdelmoula; J.-M. R. Génin

2003-01-01

80

Immobilization of strontium during iron biomineralization coupled to dissimilatory hydrous ferric oxide reduction  

SciTech Connect

Abstract: The potential for incorporation of strontium (Sr) into biogenic Fe(II)-bearing minerals formed during microbial reduction of synthetic hydrous ferric oxide (HFO) was investigated in circumneutral bicarbonate-buffered medium containing SrCl2 at concentrations of 10 muM, 100 muM, or 1.0 mM. CaCl2 (10 mM) was added to some experiments to simulate a Ca-rich groundwater. In Ca-free systems, 89 to 100% of total Sr was captured in solid-phase compounds formed during reduction of 30 to 40 mmol Fe(III) L-1 over a 1-month period. A smaller fraction of total Sr (25 to 34%) was incorporated into the solid phase in cultures amended with 10 mM CaCl2. X-ray diffraction identified siderite and ferroan ankerite as major end products of HFO reduction in Ca-free and Ca-amended cultures, respectively. Scanning electron microscopy-energy dispersive x-ray spectroscopy revealed the presence of Sr associated with carbonate phases. Selective extraction of HFO reduction end products indicated that 46 to 100% of the solid-phase Sr was associated with carbonates. The sequestration of Sr into carbonate phases in the Ca-free systems occurred systematically according to a heterogeneous (Doerner-Hoskins) partition coefficient (DD-H) of 1.81+/-0.15. This DD-H value was 2 to 10 times higher than values determined for incorporation of Sr (10 muM) into FeCO3(S) precipitated abiotically at rates comparable to or greater than rates observed during HFO reduction, and fivefold higher than theoretical partition coefficients for equilibrium Fe(Sr)CO3 solid solution formation. Surface complexation and entrapment of Sr by rapidly growing siderite crystals (and possibly other biogenic Fe(II) solids) provides an explanation for the intensive scavenging of Sr in the Ca-free systems. The results of abiotic siderite precipitation experiments in the presence and absence of excess Ca indicate that substitution of Ca for Sr at foreign element incorporation sites (mass action effect) on growing FeCO3(S) surfaces can account for the inhibition of Sr incorporation into the siderite component of ankerite formed in the Ca-amended HFO reduction experiments. Likewise, substitution of Fe(II) for Sr may explain the absence of major Sr partitioning into the calcite component of ankerite. The findings indicate that under appropriate conditions, sequestration of metals in siderite produced during bacterial Fe(III) oxide reduction may provide a mechanism for retarding the migration of Sr and other divalent metal contaminants in anaerobic, carbonate-rich sedimentary environments. Copyright (C) 2002 Elsevier Science Ltd.

Roden, Eric E.; Leonardo, Michael R.; Ferris, F. G.

2002-08-15

81

Osteoblast adhesion on nanophase ceramics  

Microsoft Academic Search

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

Thomas J Webster; Richard W Siegel; Rena Bizios

1999-01-01

82

Thermodynamic and Properties of Nanophases  

SciTech Connect

A large volume of today s research deals with nanophases of various types. The materials engineer, chemist, or physicist, however, when dealing with applications of nanophases is often unaware of the effect of the small size on structure and properties. The smallest nanophases reach the limit of phase definitions by approaching atomic dimensions. There, the required homogeneity of a phase is lost and undue property fluctuations destroy the usefulness of thermodynamic functions. In fact, itwas not expected that a definite nanophasewould exist belowthe size of a microphase.Aneffort ismadein this reviewto identify macrophases, microphases, and nanophases. It is shown that nanophases should contain no bulk matter as defined by macrophases and also found in microphases. The structure and properties of nanophases, thus, must be different from macrophases and microphases. These changes may include different crystal and amorphous structures, and phase transitions of higher or of lower temperature. The phase properties are changing continuously when going from one surface to the opposite one. The discussion makes use of results from structure determination, calorimetry, molecular motion evaluations, and molecular dynamics simulations.

Wunderlich, Bernhard {nmn} [ORNL

2009-01-01

83

Species differences in the effect of benzo(alpha)pyrene-ferric oxide on the respiratory tract of rats and hamsters.  

PubMed

When given intratracheal injections of a suspension of benzo(alpha)pyrene-ferric oxide, rats and hamsters showed striking species differences in the response of their respiratory tracts to the carcinogen. Hamsters produced squamous metaplasia of the trachea and large bronchi; in contrast, squamous cell nodules of bronchioloalveolar origin developed in rats within a few weeks after carcinogen application. The different sites of the early proliferative and metaplastic responses correlated in their location with the sites of later tumor development. There were no obvious differences between the two species in retention of benzo(alpha)pyrene in the lungs or tracheas. A species difference was observed, however, in the localization of the benzo(alpha)pyrene in the tracheal tissues using ultraviolet fluorescence microscopy. Carcinogen was found to be present in the epithelium of hamsters but not in the epithelium of rats, suggesting a species difference in penetration of carcinogen from the lumen into the tracheal tissues. PMID:1131827

Schreiber, H; Martin, D H; Pazmiño, N

1975-07-01

84

Nuclear fuel elements made from nanophase materials  

DOEpatents

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 3,000 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.

Heubeck, Norman B.

1997-12-01

85

Active Ferric and Cupric Compounds as Inorganic Catalysts in Peroxidizing Oxidation Reactions in the Light of Theories of Oxygen Activation and Hydrogen Activation.  

National Technical Information Service (NTIS)

The activity of a mixed catalyst combining cupric and ferric hydroxides in catalytic oxidation reactions of indigo dye or formic acid, for example, is discussed in terms of oxygen or hydrogen activation. It is pointed out that the activation of oxygen in ...

A. Krause

1977-01-01

86

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

PubMed Central

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.

Nganai, Shadrack; Lomnicki, Slawo; Dellinger, Barry

2012-01-01

87

Inhibition of bacterially promoted uranium reduction: Ferric (hydr)oxides as competitive electron acceptors  

Microsoft Academic Search

Reduction of hexavalent to tetravalent uranium results in a marked decrease in the mobility of this hazardous element. Microbial reduction is the most kinetic viable mechanism for such a reaction. Unfortunately, alternate terminal electron acceptors may thus compete with uranyl. We examine the role of common iron oxides on uranyl reduction. Only poorly ordered iron oxides altered the degree and

Bruce Wielinga; Benjamin Bostick; R. F. Rosenzweig; S. Fendorf

2000-01-01

88

Initiation of aqueous pyrite oxidation by dissolved oxygen and by ferric iron  

SciTech Connect

The authors studies of aqueous, abiotic pyrite oxidation in oxygen-saturated and anaerobic Fe(III)-saturated systems span pH values from 2 to 9 and include analyses of sulfite, thiosulfate, polythionates, and sulfate. In addition, they evaluated procedures for cleaning oxidation products from pyrite surfaces. As in silicate experiments, the preparation of the pyrite surface is critical to a valid interpretation of the onset of pyrite oxidation. The rates in oxygen-saturated systems (1) were relatively independent of pH, (2) gave linear sulfoxy anion production, (3) produced thiosulfate and polythionates at pH >3.9, and (4) produced intermediate sulfoxy anions only at high stirring rates. In anaerobic Fe(III)-saturated systems no intermediates were observed. From these results, along with the generally faster rate of oxidation in Fe(III)-saturated systems, we conclude that Fe(III) is the more important, direct oxidant of pyrite. This conclusion is supported by theoretical consideration regarding the low probability of a direct reaction between paramagnetic molecular oxygen and diamagnetic disulfide. The authors findings extend earlier models for the pyrite oxidation mechanism because of the larger range of experimental conditions that they have studied. Preliminary results from studies of sphalerite oxidation, in which they have found thiosulfate, support the hypothesis that thiosulfate is a key intermediate related to the reaction mechanisms, independent of the bounding structure of the sulfide mineral.

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

1985-01-01

89

Experimental constraints on Fe isotope fractionation during magnetite and Fe carbonate formation coupled to dissimilatory hydrous ferric oxide reduction  

NASA Astrophysics Data System (ADS)

Iron isotope fractionation between aqueous Fe(II) and biogenic magnetite and Fe carbonates produced during reduction of hydrous ferric oxide (HFO) by Shewanella putrefaciens, Shewanella algae, and Geobacter sulfurreducens in laboratory experiments is a function of Fe(III) reduction rates and pathways by which biogenic minerals are formed. High Fe(III) reduction rates produced 56Fe/ 54Fe ratios for Fe(II) aq that are 2-3‰ lower than the HFO substrate, reflecting a kinetic isotope fractionation that was associated with rapid sorption of Fe(II) to HFO. In long-term experiments at low Fe(III) reduction rates, the Fe(II) aq-magnetite fractionation is -1.3‰, and this is interpreted to be the equilibrium fractionation factor at 22°C in the biologic reduction systems studied here. In experiments where Fe carbonate was the major ferrous product of HFO reduction, the estimated equilibrium Fe(II) aq-Fe carbonate fractionations were ca. 0.0‰ for siderite (FeCO 3) and ca. +0.9‰ for Ca-substituted siderite (Ca 0.15Fe 0.85CO 3) at 22°C. Formation of precursor phases such as amorphous nonmagnetic, noncarbonate Fe(II) solids are important in the pathways to formation of biogenic magnetite or siderite, particularly at high Fe(III) reduction rates, and these solids may have 56Fe/ 54Fe ratios that are up to 1‰ lower than Fe(II) aq. Under low Fe(III) reduction rates, where equilibrium is likely to be attained, it appears that both sorbed Fe(II) and amorphous Fe(II)(s) components have isotopic compositions that are similar to those of Fe(II) aq. The relative order of ? 56Fe values for these biogenic minerals and aqueous Fe(II) is: magnetite > siderite ? Fe(II) aq > Ca-bearing Fe carbonate, and this is similar to that observed for minerals from natural samples such as Banded Iron Formations (BIFs). Where magnetite from BIFs has ? 56Fe >0‰, the calculated ? 56Fe value for aqueous Fe(II) suggests a source from midocean ridge (MOR) hydrothermal fluids. In contrast, magnetite from BIFs that has ? 56Fe ?0‰ apparently requires formation from aqueous Fe(II) that had very low ? 56Fe values. Based on this experimental study, formation of low-? 56Fe Fe(II) aq in nonsulfidic systems seems most likely to have been produced by dissimilatory reduction of ferric oxides by Fe(III)-reducing bacteria.

Johnson, Clark M.; Roden, Eric E.; Welch, Susan A.; Beard, Brian L.

2005-02-01

90

Nitrogen Requirement of Iron-Oxidizing Thiobacilli for Acidic Ferric Sulfate Regeneration  

PubMed Central

Ammonium was shown to be a limiting nutrient for iron oxidation in cultures of Thiobacillus ferrooxidans. In addition, one strain was also able to assimilate nitrate, but not nitrite, for growth and coupled iron oxidation. Some amino acids (0.5 mM) were tested as a source of nitrogen; none clearly stimulated bacterial activity and inhibition was commonly encountered. Complex nitrogenous compounds were inhibitory at high concentrations (0.1 to 0.5%, wt/vol) and, at low concentrations, some clearly stimulated the bacterial iron oxidation in ammonium-limited cultures. Enhancement of iron oxidation by these compounds was also observed in ammonium-unlimited cultures, suggesting their possible role in providing trace nutrients and possibly carbon for the bacteria.

Tuovinen, Olli H.; Panda, Fern A.; Tsuchiya, Henry M.

1979-01-01

91

Initiation of aqueous pyrite oxidation by dissolved oxygen and by ferric iron  

Microsoft Academic Search

The authors studies of aqueous, abiotic pyrite oxidation in oxygen-saturated and anaerobic Fe(III)-saturated systems span pH values from 2 to 9 and include analyses of sulfite, thiosulfate, polythionates, and sulfate. In addition, they evaluated procedures for cleaning oxidation products from pyrite surfaces. As in silicate experiments, the preparation of the pyrite surface is critical to a valid interpretation of the

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

1985-01-01

92

Assessment of the extent of oxidative stress induced by intravenous ferumoxytol, ferric carboxymaltose, iron sucrose and iron dextran in a nonclinical model.  

PubMed

Intravenous (i.v.) iron is associated with a risk of oxidative stress. The effects of ferumoxytol, a recently approved i.v. iron preparation, were compared with those of ferric carboxymaltose, low molecular weight iron dextran and iron sucrose in the liver, kidneys and heart of normal rats. In contrast to iron sucrose and ferric carboxymaltose, low molecular weight iron dextran and ferumoxytol caused renal and hepatic damage as demonstrated by proteinuria and increased liver enzyme levels. Higher levels of oxidative stress in these tissues were also indicated, by significantly higher levels of malondialdehyde, significantly increased antioxidant enzyme activities, and a significant reduction in the reduced to oxidized glutathione ratio. Inflammatory markers were also significantly higher with ferumoxytol and low molecular weight iron dextran rats than iron sucrose and ferric carboxymaltose. Polarographic analysis suggested that ferumoxytol contains a component with a more positive reduction potential, which may facilitate iron-catalyzed formation of reactive oxygen species and thus be responsible for the observed effects. Only low molecular weight iron dextran induced oxidative stress and inflammation in the heart. PMID:21899208

Toblli, Jorge E; Cao, Gabriel; Oliveri, Leda; Angerosa, Margarita

2011-01-01

93

A model-based evaluation of sorptive reactivities of hydrous ferric oxide and hematite for U(VI).  

PubMed

The sorption of uranyl onto hydrous ferric oxide (HFO) or hematite was measured by discontinuously titrating the suspensions with uranyl at pH 5.9, 6.8, and 7.8 under Pco2 = 10(-35)atm (sorption isotherms). Batch reactors were used with equilibration times up to 48 days. Sorption of 1 microM uranyl onto HFO was also measured versus pH (sorption edge). A diffuse double layer surface complexation model was calibrated by invoking three sorption species that were consistent with spectroscopic evidence for predominance of bidentate complexes at neutral pH and uranyl-carbonato complexes: > SOH:UO2OH(+1), (> SO)2: UO2CO3(-2), and (> SO)2:(UO2)3(OH)5(-1). The model was consistent with previously published isotherm and edge data. The model successfully predicted sorption data onto hematite, only adjusting for different measured specific surface area. Success in application of the model to hematite indicates that the hydrated surface of hematite has similar sorptive reactivity as HFO. PMID:17626429

Jang, Je-Hun; Dempsey, Brian A; Burgos, William D

2007-06-15

94

Novel approach to zinc removal from circum-neutral mine waters using pelletised recovered hydrous ferric oxide.  

PubMed

Data are presented which evaluate the performance of a pilot-scale treatment system using pelletised hydrous ferric oxide (HFO; a waste stream from coal mine water treatment) as a high surface area sorbent for removing zinc (Zn) from a metal mine water discharge in the North Pennines Orefield, UK. Over a 10-month period the system removed Zn at mean area- and volume-adjusted removal rates of 3.7 and 8.1gm(-3)day(-1), respectively, with a mean treatment efficiency of 32% at a low mean residence time of 49min. There were seasonal effects in Zn removal owing to establishment and dieback of algae in the treatment tank. This led to increased Zn uptake in early summer months followed by slight Zn release upon algae senescence. In addition to these biosorptive processes, the principal sinks for Zn appear to be (1) sorption onto the HFO surface, and (2) precipitation with calcite-dominated secondary minerals. The latter were formed as a product of dissolution of portlandite in the cement binder and calcium recarbonation. Further optimisation of the HFO pelletisation process holds the possibility for providing a low-cost, low footprint treatment option for metal rich mine waters, in addition to a valuable after-use for recovered HFO from coal mine water treatment facilities. PMID:18583040

Mayes, William M; Potter, Hugh A B; Jarvis, Adam P

2008-05-21

95

Investigation of Wüstite (FeO) dissolution: implications for reductive dissolution of ferric oxides.  

PubMed

The pH-dependent dissolution flux of FeO (wüstite, a ferrous oxide) was measured in this study; flux = k{H+}n (moV/m2/s), where k = 10(-4.95) and n = 0.64. This flux was consistent with theoretical predictions based on the rate of water exchange of hexaaquo Fe2+. Interestingly, when compared to published data, the pH-dependent dissolution flux of FeO defined an upper limit for the reductive dissolution fluxes of iron(III) (oxyhydr)oxides, including bacterial dissimilatory iron reduction (DIR). A wide range of dissolution fluxes across several orders of magnitude has been reported for iron(III) (oxyhydr)oxides in the literature and the fluxes were affected by various experimental variables, e.g., pH, ligands, chemical reductants, and bacteria. We concluded that (i) the reductive dissolution fluxes of iron(III) (oxyhydr)oxides, including bacterial DIR, are ultimately bracketed by the detachment rate of reduced Fe(II) from the surface and (ii) the maximum flux can be approached when the mole fraction of reduced Fe(II) at the surface is close to unity. PMID:19320162

Jang, Je-Hun; Brantley, Susan L

2009-02-15

96

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

Microsoft Academic Search

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

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

2006-01-01

97

21 CFR 184.1307 - Ferric sulfate.  

Code of Federal Regulations, 2013 CFR

...10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide...b)(1), the ingredient is used in food as a flavoring agent as defined in § 170.3(o)(12) of this chapter,...

2013-04-01

98

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

Microsoft Academic Search

Gold-coated magnetic nanoparticles were synthesized with size ranging from 15 to 40nm using sodium citrates as the reducing agent. Oxidized magnetites (Fe3O4) fabricated by co-precipitation of Fe2+ and Fe3+ 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

Thao Thi Hien Pham; Cuong Cao; Sang Jun Sim

2008-01-01

99

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

Microsoft Academic Search

Gold-coated magnetic nanoparticles were synthesized with size ranging from 15 to 40 nm using sodium citrates as the reducing agent. Oxidized magnetites (Fe3O4) fabricated by co-precipitation of Fe2+ and Fe3+ 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

Thao Thi Hien Pham; Cuong Cao; Sang Jun Sim

2008-01-01

100

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

PubMed

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

Mishra, S P; Tiwary, D

1999-10-01

101

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

SciTech Connect

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.

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

2007-01-01

102

The formation, structure, and ageing of As-rich hydrous ferric oxide at the abandoned Sb deposit Pezinok (Slovakia)  

NASA Astrophysics Data System (ADS)

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 ˜380,000 m 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 2; arsenopyrite, FeAsS; berthierite, FeSb 2S 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 ?-XANES experiments indicate that As in the weathering rims is fully oxidized (As 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 2O 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 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 Å, 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.

Majzlan, Juraj; Lalinská, Bronislava; Chovan, Martin; Jurkovi?, L.'ubomír; Milovská, Stanislava; Göttlicher, Jörg

2007-09-01

103

The nanophase iron mineral(s) in Mars soil.  

PubMed

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. PMID:11539182

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

1993-11-25

104

Spectral signature of oxidized pyroxenes - Implications to remote sensing of terrestrial planets  

NASA Astrophysics Data System (ADS)

The effect of the structural Fe(3+) or disseminated ferric oxides in oxidized ferromagnesian silicates on the reflectance spectral profiles of the remnant Fe(2+) ions in oxidized silicates was investigated. Results of spectral measurements in the visible NIR region, performed on several well-characterized pyroxenes representative of different structural types and compositions, were correlated with data obtained from the Mossbauer spectra of the oxidation products. The measurements made it possible to determine the relative proportions of Fe(2+) and Fe(3+) ions present in the oxidized pyroxenes and provided information on the amorphous ferric oxide phases present in the oxidation products. The results also suggest a mechanism for producing the nanophase hematite popularly considered to be responsible for the features observed around 0.62 and 0.87 micron in the remotely sensed spectra of Mars.

Straub, D'arcy W.; Burns, Roger G.; Pratt, Stephen F.

1991-10-01

105

Adsorptive selenite removal from water using a nano-hydrated ferric oxides (HFOs)/polymer hybrid adsorbent.  

PubMed

Selenite (SeO(3)(2-)) is an oxyanion of environmental significance due to its toxicity when taken in excess. In the present study, a hybrid adsorbent (HFO-201) was prepared by irreversibly impregnating hydrated ferric oxide (HFO) nanoparticles within a commercial available anion-exchange resin (D-201), and its adsorption towards selenite from water was investigated in batch and column tests. HFO-201 exhibited improved sorption selectivity toward selenite as compared to the polymeric anion exchanger D-201. Two possible adsorption interactions were responsible for selenite removal by HFO-201, the electrostatic interaction from the ammonium groups bound to the D-201 matrix, and the formation of inner-sphere complexes between the loaded HFO nanoparticles and selenite. In a wide pH range (i.e., 3-8), increasing solution pH was found to result in a decrease of selenite removal on HFO-201. Adsorption isotherms fit the Freundlich model well, and selenite adsorption increased with increasing ambient temperature, indicating its endothermic nature. Column adsorption tests suggested that satisfactory removal of selenite from 2 mg/L to less than 0.01 mg/L could be achieved by HFO-201 even in the presence of the commonly encountered anionic competition at greater concentration, with the treatment capacity of approximately 1200 bed volume (BV) per run, while that for D-201 was only less than 30 BV under otherwise identical conditions. Furthermore, the exhausted HFO-201 was amenable to efficient in situ regeneration with a binary NaOH-NaCl solution. PMID:20082026

Pan, Bingjun; Xiao, Lili; Nie, Guangze; Pan, Bingcai; Wu, Jun; Lv, Lu; Zhang, Weiming; Zheng, Shourong

2009-09-25

106

Enhanced functions of osteoblasts on nanophase ceramics  

Microsoft Academic Search

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

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

2000-01-01

107

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2013 CFR

...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)...

2013-04-01

108

In-situ Neutron Diffraction Studies of the Reduction of a Model of an Oxidations Catalyst (ferric molybdate and bismuth molybdate)  

NASA Astrophysics Data System (ADS)

Three elements commonly found in metal oxide alkene oxidation catalysts are molybdenum, bismuth and iron. In the case of ammoxidation of propylene to acrylonitrile many catalyst have ferric molybdate and a mixture of bismuth molybdates present in the as-prepared formulations. It is generally recognized that during catalyst activation ferric molybdate is reduced to Fe^+2 phases, freeing molybdenum oxide for the formation of other phases. It is suspected, but has never been demonstrated, that this excess MoO3 then reacts with the bismuth containing phase(s) to form the active catalyst phase. Although this reaction is generally believed to occur in a number of catalytic processes the mechanism of the reaction has never been extensively studied. Due to the ease of in-situ measurements and the sensitivity to oxygen in the presence of heavy metals neutron diffraction is an ideal probe to study this reaction mechanism. We have developed a reaction cell that can be used in the General Purpose Powder Diffractometer at IPNS, ANL for time resolved in situ study. Recent upgrades to GPPD, which have increased data rates by a factor of 6, now make these measurements possible. Preliminary findings about the evolution of a model oxidation catalyst under reaction conditions will be presented in this talk.

Huq, Ashfia

2005-03-01

109

Upper mantle oxidation state: Ferric iron contents of Iherzolite spinels by 57 Fe Mössbauer spectroscopy and resultant oxygen fugacities  

Microsoft Academic Search

The ferric iron contents of spinels from 30 spinel Iherzolite xenoliths have been measured by 57 Fe Mössbauer spectroscopy. The samples are widely dispersed in geographic and tectonic setting, coming from Southwest United States (San Carlos, Kilbourne Hole), Japan (Ichinomegata), Massif Central, France (Mont Briançon) and Central Asia (Tariat Depression, Vitim Plateau). The total range of Fe 3 O 4

Bernard J. Wood; David Virgo

1989-01-01

110

Effects of a cocarcinogen, ferric oxide, on the metabolism of benzo(a)pyrene in the isolated perfused lung  

SciTech Connect

An isolated perfused New Zealand rabbit lung preparation was used to investigate the effects of a cocarcinogen, ferric oxide (Fe/sub 2/O/sub 3/), on the metabolism of benzo(a)pyrene (BaP), a ubiquitous potent carcinogen that has been associated with the increased incidence of human bronchiogenic carcinoma in occupational and urban settings. (/sup 14/C)-BaP was administered intratracheally to an isolated perfused lung (IPL) preparation with and without Fe/sub 2/O/sub 3/ after intraperitoneal pretreatment of the whole animal with BaP or intratracheal pretreatment of the whole animal with Fe/sub 2/O/sub 3/ and/or BaP. BaP and its metabolites were isolated from serial blood samples up to 180 min after administration of (/sup 14/C)BaP to the IPL. BaP and its metabolites were also isolated from lung tissue, washout fluid, macrophage, and trachea bronchi at the end of the perfusion at 180 min. Patterns of BaP metabolites were determined by chromatographic techniques and liquid scintillation counting. Fe/sub 2/O/sub 3/ pretreatment to the whole animal or administration of Fe/sub 2/O/sub 3/ to the IPL altered BaP metabolism by the perfused lung. Fe/sub 2/O/sub 3/ pretreatment to the whole animal resulted in an increase in the total rate of appearance of metabolites of BaP in the blood, while Fe/sub 2/O/sub 3/ administration to the IPL resulted in a decrease in the total rate of appearance of BaP metabolites in the blood and inhibited the effect of pretreatment. These data suggest that pulmonary exposure to a known cocarcinogen, Fe/sub 2/O/sub 3/, in the presence of BaP results in increased production of dihydrodiols of BaP, which may be further metabolized to the ultimate carcinogenic form(s) of BaP. Therefore, Fe/sub 2/O/sub 3/ can enhance the metabolic activation of BaP by the lung, as well as act as a carrier for penetration and retention of BaP in the lung. 49 references, 6 tables.

Warshawsky, D.; Bingham, E.

1984-01-01

111

Upper mantle oxidation state: Ferric iron contents of Iherzolite spinels by 57Fe Mössbauer spectroscopy and resultant oxygen fugacities  

NASA Astrophysics Data System (ADS)

The ferric iron contents of spinels from 30 spinel Iherzolite xenoliths have been measured by 57Fe Mössbauer spectroscopy. The samples are widely dispersed in geographic and tectonic setting, coming from Southwest United States (San Carlos, Kilbourne Hole), Japan (Ichinomegata), Massif Central, France (Mont Briançon) and Central Asia (Tariat Depression, Vitim Plateau). The total range of Fe 3O 4 contents of the spinels is from 1.7 to 5.2 mol% with an uncertainty of 0.2 to 0.3 mol%. These data were used to calculate the oxygen fugacities recorded by the spinel Iherzolites using the oxygen thermobarometer 6 Fe 2SiO 4 + O 2 = 3 Fe 2Si 2O 6 + 2 Fe 3O 4. olivine orthopyroxene spinel The Fe(III) contents of the spinels translate to oxygen fugacities which, at 15 kb, range between 1.7 log units below and 1.2 log units above FMQ using either the Mattioli and Wood (1988) or O'neill and Wall (1987) version of Fe 3O 4 activity. There are distinct regional differences ƒO 2, the specimens from SW U.S.A. and Central Asia exhibiting values from slightly above FMQ to 1.5 log units below FMQ. At an estimated pressure of 15 kb, these values overlap with the ƒO 2- T field of MORB glasses, indicating, in agreement with trace element abundances, that many of these samples are related to the MORB source region. Samples from Ichinomegata and Mont Briançon are all above the MORB range, however, suggesting progressive oxidation related to subduction processes. All of our samples give oxygen fugacities more than 2 log units above IW, implying that C?H?O fluids in the upper mantle are dominated by CO 2 and H 2O and that CH 4 is a minor (< 10%) component. A detailed comparison of Fe(III) contents determined by Mössbauer spectroscopy and those obtained from microprobe analysis indicates that the latter are sufficiently precise (± 0.002 fXFe3O 4) but, in general, too inaccurate for oxygen thermobarometry. Use of Mössbauer-analyzed spinels as microprobe standards enables accuracy to approach precision, however, and appropriate standards are available on request.

Wood, Bernard J.; Virgo, David

112

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

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

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

2010-01-01

113

Sodium Ferric Gluconate Complex  

Center for Drug Evaluation (CDER)

Text Version... Draft Guidance on Sodium Ferric Gluconate Complex ... Active ingredient: Sodium Ferric Gluconate Complex Form/Route: Injectable; Injection ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

114

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

Microsoft Academic Search

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

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

2011-01-01

115

Synthesis and characterization of nanophase zirconia : reverse micelle method and neutron scattering study.  

SciTech Connect

Zirconia is an important transition-metal oxide for catalytic applications. It has been widely used in automotive exhaust treatment, methanol synthesis, isomerization, alkylation, etc. [1]. Nanophase materials have unique physiochemical properties such as quantum size effects, high surface area, uniform morphology, narrow size distribution, and improvement of sintering rates[2]. Microemulsion method provides the means for controlling the microenvironment under which specific chemical reactions may occur in favoring the formation of homogeneous, nanometer-size particles. In this paper, we report the synthesis of nanophase zirconia and the characterization of the microemulsions as well as the powders by small- and wide-angle neutron scattering techniques.

Li, X.

1998-11-23

116

High density cultivation of two strains of iron-oxidizing bacteria through reduction of ferric iron by intermittent electrolysis.  

PubMed

Electrolytic cultivation was applied to Leptospirillum ferrooxidans strains P3A and CF27, which use ferrous iron to respire aerobically. Ferrous iron was supplied to the bacteria by intermittent electrolytic reduction of ferric iron as electron shuttle using an electrode. The yield of L. ferrooxidans and strain CF27 reached 20- and 50-fold, respectively, higher density than were achievable yields without electrolysis. The time required to obtain high density depended not on the growth ratio, but rather on the original growth rate of each strain. PMID:11005929

Matsumoto, N; Yoshinaga, H; Ohmura, N; Ando, A; Saiki, H

2000-11-20

117

Do grain boundaries in nanophase metals slide?  

SciTech Connect

Nanophase metallic materials show a maximum in strength as grain size decreases to the nano scale, indicating a break down of the Hall-Petch relation. Grain boundary sliding, as a possible accommodation mechanisms, is often the picture that explain computer simulations results and real experiments. In a recent paper, Bringa et al. Science 309, 1838 (2005), we report on the observation of an ultra-hard behavior in nanophase Cu under shock loading, explained in terms of a reduction of grain boundary sliding under the influence of the shock pressure. In this work we perform a detailed study of the effects of hydrostatic pressure on nanophase Cu plasticity and find that it can be understood in terms of pressure dependent grain boundary sliding controlled by a Mohr-Coulomb law.

Bringa, E M; Leveugle, E; Caro, A

2006-10-27

118

Synthesis and properties of nanophase materials  

SciTech Connect

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.

Siegel, R.W.

1993-03-01

119

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

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.

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

1990-01-01

120

Kinetics of chemoheterotrophic microbially mediated reduction of ferric EDTA and the nitrosyl adduct of ferrous EDTA for the treatment and regeneration of spent nitric oxide scrubber liquor.  

PubMed

Biomass from a prototype reactor was used to investigate the kinetics of chemoheterotrophic reduction of solutions of ferric ethylenediaminetetraacetic acid (EDTA) and solutions containing the nitrosyl adduct of ferrous EDTA using ethanol as the primary electron donor and carbon source. A series of batch experiments were conducted using biomass extracted from the scrubber solution treatment and regeneration stage of a prototype iron EDTA-based unit process for the absorption of nitric oxide with subsequent biological treatment. Using a linear-sweep voltammetric method for analysis of the ferric EDTA concentration, iron-reducing bacteria were found to behave according to the Monod kinetic model, at initial concentrations up to 2.16 g chemical oxygen demand (COD) as ethanol per liter, with a half-velocity constant of 0.532 g COD as ethanol/L and a maximum specific utilization rate of 0.127 mol/L of ferric ethylenediamine-tetraacetic acid [Fe(III)EDTA]*(g volatile suspended solids [VSS]/L)d(-1). Based on batch analyses, biomass yield and endogenous decay values of iron-reducing bacteria were estimated to be 0.055 g VSS/g COD and 0.017 L/d, respectively. An average of 1.64 times the theoretical (stoichiometric) demand of ethanol was used to complete reduction reactions. Kinetics of the reduction of the nitrosyl adduct of ferrous EDTA are summarized by the following kinetic constants: half-velocity constant (Ks) of 0.39 g COD/L, maximum specific utilization rate (k) of 0.2 mol/L [NO x Fe(II)EDTA(2-)](g VSS/L)d(-1), and inhibition constant (K(I)) of 0.33 g COD/L, as applied to the modified Monod kinetic expression described herein. Based on batch analyses, the biomass yield of nitrosyl-adduct-reducing bacteria was estimated to be 0.259 g VSS/g COD, endogenous decay was experimentally determined to be 0.0569 L/d, and an average of 1.26 times the stoichiometric demand of ethanol was used to complete reduction reactions. PMID:17571837

Dilmore, Robert; Neufeld, Ronald D; Hammack, Richard W

2007-05-01

121

Preparation of La 0.75 Sr 0.25 MnO 3 Nano-Phase Powders and Films from Alkoxide Precursors  

Microsoft Academic Search

The first purely alkoxide-based sol-gel route to nano-phase powders and thin films of perovskite La0.75Sr0.25MnO3 is described. The phase and microstructure evolution on heat treatment of free gel films to form the target nano-phase oxide were investigated by TGA, IR spectroscopy, powder XRD, SEM and TEM-EDS. The xerogel consisted of a hydrated oxo-carbonate, without remaining alkoxo groups or solvent. Heating

Annika Pohl; Gunnar Westin; Kjell Jansson

2003-01-01

122

Sodium ferric gluconate causes oxidative stress but not acute renal injury in patients with chronic kidney disease: a pilot study  

Microsoft Academic Search

Background. Intravenous (i.v) iron is widely used to treat anaemia in patients with chronic kidney disease (CKD). Although beneficial and usually well tolerated, concerns have been raised about its ability to cause oxidative stress and renal injury. Methods. To determine if i.v. iron causes oxidative stress (as assessed by plasma and urine malondialdehye (MDA)) and\\/or renal injury (as assessed by

David J. Leehey; David J. Palubiak; Srivasa Chebrolu; Rajiv Agarwal

123

Benzo[a]pyrene coated ferric oxide and aluminum oxide particles: uptake, metabolism and DNA binding in hamster pulmonary alveolar macrophages and tracheal epithelial cells in vitro.  

PubMed

Ferric oxide (Fe2O3) and aluminum oxide (Al2O3) particles are widely encountered in occupational settings. Benzo[a]pyrene (B[a]P), a well-characterized environmental carcinogen, is frequently adsorbed onto particles. It has been shown that B[a]P-coated Fe2O3 particles (B[a]P-Fe2O3) significantly increased lung tumors in the hamster in contrast to B[a]P-coated Al2O3 (B[a]P-Al2O3) or B[a]P alone. In order to determine the genotoxic effects of these particles on the metabolism of B[a]P, pulmonary alveolar macrophages (AM) from male Syrian golden hamsters were incubated with 5 microg (19.8 nmol) B[a]P-coated respirable size (99% < 5 microm) Fe2O3 and Al2O3 particles with loads from 0.5 to 2.0 mg. Intracellular uptake of B[a]P by AM at 24 h was higher with B[a]P-Fe2O3 than that of B[a]P alone (P < 0.05) or B[a]P-Al2O3 (P < 0.05). Total B[a]P metabolism was significantly greater in AM exposed to B[a]P-coated Fe2O3 at 1.0 and 1.5 mg than in the AM exposed to B[a]p-al2O3 (0.5, 1.0 and 1.5 mg) (P < 0.05) or B[a]P alone (P < 0.05). Similar significant differences for Fe2O3 relative to Al2O3 and B[a]P alone were also apparent for total dihydrodiols, quinones and phenolic metabolites. Co-administration of 5 microg alpha-naphthoflavone (alpha-NF, an inhibitor of cytochrome P-4501A1 and P-4501A2) and 10(-3) M cyclohexene oxide (CO, an inhibitor of epoxide hydrolase) significantly reduced B[a]P metabolism in B[a]P-Fe2O3 (P < 0.05) and B[a]P-Al2O3 (P < 0.05) treated groups relative to B[a]P alone. AM were co-cultured with hamster tracheal epithelial cells (HTE) and treated as described above for metabolism studies to assess the DNA binding of B[a]P metabolites in the target cells, using 32P-postlabeling techniques. Two adducts were observed that had chromatographic behavior similar to 7R,8S,9S-trihydroxy-10R-(N2-deoxyguanosyl-3'-phosphate)-7,8,9,10-t etrahydrobenzo[a]pyrene [(+)-anti-BPDE-dG, adduct 1, major adduct representing 70-80% of total adducts] and 7S,8R,9R-trihydroxy-10S-(N2-deoxyguanosyl-3'-phosphate)-7,8,9,10-t etrahydrobenzo[a]pyrene [(-)-anti-BPDE-dG, adduct 2, representing 20-30% of total adducts]. B[a]P-Fe2O3 treatment enhanced the levels of the two B[a]P-DNA adducts in the HTE compared with B[a]P-Al2O3 (P < 0.05) or B[a]P alone. The inhibitors alphaNF and CO significantly reduced total adduct levels in the HTE (P < 0.05) in the B[a]P and B[a]P-Fe2O3 treatments as well as adduct 1 and adduct 2 levels. Our data suggest that the cocarcinogenic effect of B[a]P-Fe2O3 relative to B[a]P-coated Al2O3 can be due to: (i) the enhancement of B[a]P metabolism in AM by Fe2O3 associated with the increased uptake of B[a]P; and (ii) augmentation of DNA adduct formation in epithelial cells. PMID:9054603

Cheu, J; Talaska, G; Miller, M; Rice, C; Warshawsky, D

1997-01-01

124

Increased ferric iron content and iron-induced oxidative stress in the brains of scrapie-infected mice  

Microsoft Academic Search

Scrapie is a transmissible neurodegenerative disease of sheep and goats. The neuropathological changes include vacuolation, astrocytosis, the development of amyloid plaques in some instances, and neuronal loss. The mechanisms involved in neuronal cell death in scrapie are not known. Recently, we reported the presence of oxidative stress in the brains of scrapie-infected animals and suggested that this is the main

Nam-Ho Kim; Seok-Joo Park; Jae-Kwang Jin; Myung-Sang Kwon; Eun-Kyoung Choi; Richard I. Carp; Yong-Sun Kim

2000-01-01

125

Oxidation of ferric-cytochrome c by N, N'-bis (2-hydroperoxy-2-methoxyethyl)-1,4,5,8-naphthalene tetracarboxylic diimide, NP III--site specific modification of cytochrome c.  

PubMed

When the synthetic hydroxyl radical generator, N, N'-bis (2-Hydroperoxy-2-methoxyethyl)-1,4,5,8-naphthalene-tetracarboxylic diimide, NP III, was photoirradiated in the presence of ferric-cytochrome c (Fe3+), the fragmentation peak corresponding to the specific oxidative modification at the histidine site of cytochrome c was observed in the Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectroscopy (MALDI-TOF) measurement. Without photoirradiation, no such protein oxidation was observed in the experimental conditions employed. This result suggests the possible usage of NP-III as an oxidative protein-modifying reagent. PMID:9305525

Matsugo, S; Yasui, F; Konishi, T

1997-09-01

126

DEPARTMENT OF CHEMICAL ENGINEERING PROGRESS REPORT NO. 1, FEBRUARY 1, 1957- OCTOBER 31, 1958. PART I. ADSORPTION OF CALCIUM AND STRONTIUM ON HYDROUS FERRIC OXIDE AND LIMONITE. PART II. PERCOLATION STUDIES  

Microsoft Academic Search

A review of the literature was made on the adsorption of ions by the ; compounds of iron and related compounds. The investigation of the absorption of ; calcium on hydrous ferric oxide and limonite covered a range of solution pH from ; 6.0 to 10.0 and equilibrium calcium solution concentrations from 1.0 x 10⁻⁴ ; to 5.0 x 10⁻²

A. A. Jr. Armstrong; B. L. Baker

1963-01-01

127

Selective mineralization of microbes in Fe-rich precipitates (jarosite, hydrous ferric oxides) from acid hot springs in the Waiotapu geothermal area, North Island, New Zealand  

NASA Astrophysics Data System (ADS)

A group of small springs that are informally called “Orange Spring”, located near Hakereteke Stream in the northern part of the Waiotapu geothermal area, feed hot (˜ 80 °C), acidic (pH: 2.1 2.4), As-rich sulfate waters into a discharge channel that is up to 25 cm deep. Submerged reddish-brown precipitates on the channel floor are formed largely of noncrystalline As-rich hydrous ferric oxide (HFO: mainly goethite), poorly crystalline lepidocrocite, and crystalline jarosite. Well-preserved coccoid and rod-shaped microbes are found in the As-rich HFO, but not in the lepidocrocite or jarosite. The jarosite was probably precipitated when the water had a low pH (< 3) and high SO4 content, whereas the goethite and lepidocrocite were probably precipitated when the water had a slightly higher pH (> 4) and lower SO4 content. The fluctuations in the pH and SO4 content, which led to precipitation of the different mineral phases, may reflect mixing of the spring water with stream water that flowed through the channel when Hakereteke Stream was in flood stage. The goethite probably formed when coccoid and rod-shaped bacteria (Acidithiobacillus ferrooxidans?) mediated rapid oxidization of the Fe2+ to Fe3+ that was then immediately coprecipitated with the As. Such rapid precipitation promoted mineralization of the microbes. The lack of mineralized microbes and the lower As in the lepidocrocite and jarosite may reflect precipitation rates that were slower than the decay rates of the microbes, or ecological factors that limited their growth.

Jones, Brian; Renaut, Robin W.

2007-01-01

128

Effect of La2O3-treatment on textural and solid-solid interactions in ferric/cobaltic oxides system  

NASA Astrophysics Data System (ADS)

Pure and La2O3-containing (0.75-3.0 mol%) Fe2O3/Co3O4 solids were prepared by thermal treatment of their carbonates at 500-700 °C. The produced solids were characterized using XRD, HRTEM, EDX and nitrogen adsorption at -196 °C. The results revealed that pure solids calcined at 600 and 700 °C consisted of nanosized CoFe2O4 phase, while pure mixed solids calcined at 500 °C consisted of trace amount of CoFe2O4 and unreacted Fe2O3, Co3O4 phases. The presence of 0.75 mol% La2O3 enhanced solid-solid interaction between Fe2O3 and Co3O4 at 500 °C yielding CoFe2O4. The ferrite phase existed also in all mixed oxides upon treated with La2O3 besides LaCoO3 phase. LaCoO3 existed as a major phase in all mixed oxides treated with 3 mol% La2O3. La2O3-treatment modified the crystallite size of all phases present to an extent dependent on calcination temperature and amount of La2O3 content. This treatment decreased effectively the SBET of all mixed solids.

Fagal, Gehan A.; Badawy, Abdelrahman A.; Hassan, Neven A.; El-Shobaky, Gamil A.

2012-10-01

129

Ferric Tourmaline from Mexico.  

PubMed

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

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

1964-04-01

130

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

PubMed

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

Azam, Hossain M; Finneran, Kevin T

2012-10-11

131

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.  

PubMed

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 microarrays containing 691 arrayed genes, and two-dimensional polyacrylamide gel electrophoresis. Physiological studies indicated that FUR1 was similar to the wild-type strain when they were compared for anaerobic growth and reduction of various electron acceptors. Transcription profiling, however, revealed that genes with predicted functions in electron transport, energy metabolism, transcriptional regulation, and oxidative stress protection were either repressed (ccoNQ, etrA, cytochrome b and c maturation-encoding genes, qor, yiaY, sodB, rpoH, phoB, and chvI) or induced (yggW, pdhC, prpC, aceE, fdhD, and ppc) in the fur mutant. Disruption of fur also resulted in derepression of genes (hxuC, alcC, fhuA, hemR, irgA, and ompW) putatively involved in iron uptake. This agreed with the finding that the fur mutant produced threefold-higher levels of siderophore than the wild-type strain under conditions of sufficient iron. Analysis of a subset of the FUR1 proteome (i.e., primarily soluble cytoplasmic and periplasmic proteins) indicated that 11 major protein species reproducibly showed significant (P < 0.05) differences in abundance relative to the wild type. Protein identification using mass spectrometry indicated that the expression of two of these proteins (SodB and AlcC) correlated with the microarray data. These results suggest a possible regulatory role of S. oneidensis MR-1 Fur in energy metabolism that extends the traditional model of Fur as a negative regulator of iron acquisition systems. PMID:11823232

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

2002-02-01

132

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  

PubMed Central

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 microarrays containing 691 arrayed genes, and two-dimensional polyacrylamide gel electrophoresis. Physiological studies indicated that FUR1 was similar to the wild-type strain when they were compared for anaerobic growth and reduction of various electron acceptors. Transcription profiling, however, revealed that genes with predicted functions in electron transport, energy metabolism, transcriptional regulation, and oxidative stress protection were either repressed (ccoNQ, etrA, cytochrome b and c maturation-encoding genes, qor, yiaY, sodB, rpoH, phoB, and chvI) or induced (yggW, pdhC, prpC, aceE, fdhD, and ppc) in the fur mutant. Disruption of fur also resulted in derepression of genes (hxuC, alcC, fhuA, hemR, irgA, and ompW) putatively involved in iron uptake. This agreed with the finding that the fur mutant produced threefold-higher levels of siderophore than the wild-type strain under conditions of sufficient iron. Analysis of a subset of the FUR1 proteome (i.e., primarily soluble cytoplasmic and periplasmic proteins) indicated that 11 major protein species reproducibly showed significant (P < 0.05) differences in abundance relative to the wild type. Protein identification using mass spectrometry indicated that the expression of two of these proteins (SodB and AlcC) correlated with the microarray data. These results suggest a possible regulatory role of S. oneidensis MR-1 Fur in energy metabolism that extends the traditional model of Fur as a negative regulator of iron acquisition systems.

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

2002-01-01

133

Autoxidation and MAO-mediated metabolism of dopamine as a potential cause of oxidative stress: role of ferrous and ferric ions  

Microsoft Academic Search

The autoxidation and monoamine oxidase (MAO)-mediated metabolism of dopamine (3-hydroxytyramine; DA) cause a continuous production of hydroxyl radical (OH), which is further enhanced by the presence of iron (ferrous iron, Fe2+ and ferric ion, Fe3+). The accumulation of hydrogen peroxide (H2O2) in the presence of Fe2+ appears to discard the involvement of the Fenton reaction in this process. It has

Álvaro Hermida-Ameijeiras; Estefan??a Méndez-Álvarez; Sof??a Sánchez-Iglesias; Carolina Sanmart??n-Suárez; Ramón Soto-Otero

2004-01-01

134

Influence of nanophase titania topography on bacterial attachment and metabolism  

PubMed Central

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.

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

2008-01-01

135

Synthesis, characterization, and properties of nanophase TiO2  

Microsoft Academic Search

Ultrafine-grained, nanophase samples of TiOâ (rutile) were synthesized by the gas-condensation method and subsequent in situ compaction. The samples were studied by a number of techniques, including transmission electron microscopy, Vickers microharness measurements, and positron annihilation spectroscopy, as a function of sintering temperature. The nanophase compacts with average initial grain sizes of 12 nm were found to densify rapidly above

R. W. Siegel; S. Ramasamy; H. Hahn; Li Zongquan; Lu Ting; R. Gronsky

1988-01-01

136

21 CFR 184.1298 - Ferric citrate.  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 true Ferric citrate. 184.1298 Section 184.1298 Food and Drugs FOOD AND DRUG ADMINISTRATION...Listing of Specific Substances Affirmed as GRAS § 184.1298 Ferric citrate. (a) Ferric citrate...

2010-01-01

137

Commercial exploitation of nanophase powder formed with exploding wire technology. Final report  

SciTech Connect

In this report, the region of the energy density under the uniform heating conditions, of the lower pressures of the gas environment and of the smaller wire diameter have been studied. Here, the theoretical investigations of exploding wire and powder formation processes are presented, the results of experimental investigations are discussed. It is demonstrated that exploding wire technique is able to produce nanophase powders of aluminum and iron oxides with the mean surface size of 30 nm or less at commercial quantities per hour and the cost of no more than $1,000 per kilogram. Here too, decisions for theoretical and technical activity during future program are recommended.

NONE

1996-10-01

138

Inhibitory Effect of Soil Organic Matter on the Crystallization of Amorphous Ferric Hydroxide  

Microsoft Academic Search

SOILS and sediments often contain large quantities of hydrous ferric oxide which, according to X-ray analysis, cannot be accounted for by crystalline forms of iron oxide. This is surprising in view of the fact that crystallization in vitro of freshly prepared amorphous ferric hydroxide to goethite or haematite is virtually complete after a few months or years, even at room

U. Schwertmann

1966-01-01

139

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

SciTech Connect

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.

Tushar K Ghosh

2008-10-13

140

Ferric citrate CYP2E1-independently promotes alcohol-induced apoptosis in HepG2 cells via oxidative/nitrative stress which is attenuated by pretreatment with baicalin.  

PubMed

In the case of alcoholic liver injury, an iron overload is always present. Both alcohol and iron can individually induce oxidative stress in liver. However, the combined effect of physiological concentrations of alcohol and iron on oxidative stress in hepatocytes remains unknown. Baicalin has been demonstrated to be an antioxidant or iron chelator in animal experiments. In this study, we investigated the injury to hepatocytes CYP2E1-independently induced by the combination of alcohol and iron and the protective effect of baicalin. Compared with cells treated with ethanol alone, ferric citrate enhanced the accumulation of reactive oxygen and nitrogen species, increased the occurrence of protein carbonylation/nitration and the levels of 4-hydroxy-2-nonenal, changed the distribution of iNOS, and eventually resulted in apoptosis. However, pretreatment with baicalin inhibited the oxidative stress induced by the combination of alcohol and iron, mainly by chelating iron. Our findings therefore suggest that iron could CPY2E1-independently enhance the oxidative stress induced by alcohol, which probably contributes to the pathogenesis of alcoholic liver disease. Baicalin is a promising phytomedicine for preventing alcoholic liver disease. PMID:22699086

Xu, Yan; Feng, Yunchao; Li, Hailing; Gao, Zhonghong

2012-06-12

141

Molecular Structure of Ferric chloride  

NSDL National Science Digital Library

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.

2002-08-27

142

Nanophase separation in monodisperse rodcoil diblock polymers  

SciTech Connect

The authors have observed nanophase-separated structures in rodcoil polymers synthesized in their laboratory. Each polymer consists of a perfectly monodisperse, rodlike segment covalently bonded to a coil like segment of polyisoprene such that both rod and coil share the same molecular backbone. The polyisoprene was prepared by living anionic polymerization, and thus the rodcoil diblock molecules in the systems studied are of fairly uniform molar mass. Annealing of solution-cast thin films approximately 5--10 nm thick leads to ordered nanoscale morphologies that depend upon the volume fraction of rod segments in these diblock molecules. The authors find by transmission electron microscopy that the morphology varies from alternating strips of rod- and coil-rich domains to discrete aggregates of rods arranged in a hexagonal superlattice as rod volume fraction is decreased. At an intermediate volume fraction the authors see a coexistence of strips and aggregates. This breakup of rod domains may be the result of entropic coil stretching penalties analogous to those postulated recently by Williams and Fredrickson in lamellar assemblies of rodcoils.

Radzilowski, L.H.; Stupp, S.I. (Univ. of Illinois, Urbana, IL (United States))

1994-12-19

143

Raman Mapping for the Investigation of Nano-phased Materials  

NASA Astrophysics Data System (ADS)

Nanosized and nanophased materials exhibit special properties. First they offer a good compromise between the high density of chemical bonds by unit volume, needed for good mechanical properties and the homogeneity of amorphous materials that prevents crack initiation. Second, interfaces are in very high concentration and they have a strong influence on many electrical and redox properties. The analysis of nanophased, low crystallinity materials is not straigtforward. The recording of Raman spectra with a geometric resolution close to 0.5 \\upmu {text{ m}^3} and the deep understanding of the Raman signature allow to locate the different nanophases and to predict the properties of the material. Case studies are discussed: advanced polymer fibres, ceramic fibres and composites, textured piezoelectric ceramics and corroded (ancient) steel.

Gouadec, G.; Bellot-Gurlet, L.; Baron, D.; Colomban, Ph.

144

Superhard nanophase cutter materials for rock drilling applications  

SciTech Connect

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.

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

2000-06-23

145

Grain size dependent mechanical properties in nanophase materials  

SciTech Connect

It has become possible in recent years to synthesize metals and ceramics under well controlled conditions with constituent grain structures on a manometer size scale (below 100 nm). These new materials have mechanical properties that are strongly grain-size dependent and often significantly different than those of their coarser grained counterparts. Nanophase metals tend to become stronger and ceramics are more easily deformed as grain size is reduced. The observed mechanical property changes appear to be related primarily to grain size limitations and the large percentage of atoms in grain boundary environments. A brief overview of our present knowledge about the grain-size dependent mechanical properties of nanophase materials is presented.

Siegel, R.W. [Argonne National Lab., IL (United States); Fougere, G.E. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering

1995-02-01

146

The kinetics of leaching galena with ferric nitrate  

NASA Astrophysics Data System (ADS)

The kinetics of leaching galena with ferric nitrate as oxidant has been studied. Experimental results indicate that the rate of galena dissolution is controlled by surface chemical reaction. Rate is proportional to the square root of the concentration of ferric ion. The addition of more than one mole/liter sodium nitrate decreases reaction rate. With nitrate additions below this concentration, rate either remains constant or is slightly enhanced. An activation energy of 47 kJ/mol was measured, and rate is proportional to the inverse of the initial size of galena particles. These results are explained in terms of mixed electrochemical control. The anodic reaction involves the oxidation of galena to lead ion and elemental sulfur, and the cathodic reaction involves the reduction of ferric ion to ferrous ion.

Fuerstenau, M. C.; Nebo, C. O.; Elango, B. V.; Han, K. N.

1987-03-01

147

The isolation and use of iron-oxidizing, moderately thermophilic acidophiles from the Collie coal mine for the generation of ferric iron leaching solution.  

PubMed

Moderately thermophilic, iron-oxidizing acidophiles were enriched from coal collected from an open-cut mine in Collie, Western Australia. Iron-oxidizers were enriched in fluidized-bed reactors (FBR) at 60 degrees C and 70 degrees C; and iron-oxidation rates were determined. Ferrous iron oxidation by the microbiota in the original coal material was inhibited above 63;C. In addition to four iron-oxidizers, closely related to Sulfobacillus spp that had been earlier isolated from the 60 degrees C FBR, one heterotroph closely related to Alicyclobacillus spp was isolated. The Alicyclobacillus sp. isolated from the Collie coal mine tolerated a lower pH than known Alicyclobacillus spp and therefore may represent a new species. The optimum temperature for growth of the iron-oxidizing strains was approximately 50 degrees C and their maximum temperatures were approximately 60 degrees C. The FBR was adjusted to operate at 50 degrees C and was inoculated with all of the isolated iron-oxidizing strains. At 60 degrees C, an iron-oxidation rate of 0.5 g Fe(2+) l(-1) x h(-1) was obtained. At 50 degrees C, the iron-oxidation rate was only 0.3 g Fe(2+) l(-1) x h(-1). These rates compare favourably with the iron-oxidation rate of Acidianus brierleyi in shake-flasks, but are considerably lower than mesophilic iron-oxidation rates. PMID:12664157

Kinnunen, P H-M; Robertson, W J; Plumb, J J; Gibson, J A E; Nichols, P D; Franzmann, P D; Puhakka, J A

2002-12-19

148

Spectroscopic studies of swift heavy ion irradiated nanophase mullite  

Microsoft Academic Search

Photoluminescence (PL) studies of 100 MeV swift Ag8+ ion bombarded combustion synthesized nanophase mullite has been studied at room temperature (RT) and the results are reported here. A pair of PL bands, one broad band centres at ˜550 nm and another sharp one at ˜690 nm are observed with excitation by a 442 nm laser beam. However, when the sample

H. Nagabhushana; B. N. Lakshminarasappa; S. C. Prashantha; K. R. Nagabhushana; Fouran Singh

2006-01-01

149

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

Microsoft Academic Search

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

Meng-Dawn Cheng

2004-01-01

150

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...

151

21 CFR 184.1301 - Ferric phosphate.  

Code of Federal Regulations, 2013 CFR

...phosphate with ferric chloride or ferric citrate. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), pp. 118-120, which is incorporated by reference. Copies are available from the National Academy...

2013-04-01

152

BAM R25: Ferric Chloride, 10%  

Center for Food Safety and Applied Nutrition (CFSAN)

... BAM R25: Ferric Chloride, 10%. January 2001. Bacteriological Analytical Manual. R25 Ferric Chloride, 10%. FeCl 3, 10 g. ... More results from www.fda.gov/food/foodscienceresearch/laboratorymethods

153

21 CFR 582.5301 - Ferric phosphate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5301 Ferric phosphate. (a) Product. Ferric phosphate. (b)...

2013-04-01

154

21 CFR 582.5304 - Ferric pyrophosphate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate....

2013-04-01

155

Pre-oxidation of high-sulfur and high-arsenic refractory gold concentrate by ozone and ferric ions in acidic media  

Microsoft Academic Search

Owing to precious metals and hazardous elements contained in high-sulfur and high-arsenic refractory gold concentrate (HGC), effective treatment of HGC can have both economic and environmental benefits. In this paper, pre-oxidation HGC by ozone and Fe (III) in acidic media and subsequent cyanide leaching of the pretreated ores were investigated. An L9 (four factors in three levels) standard orthogonal array

Qingcui Li; Dengxin Li; Fangjun Qian

2009-01-01

156

Spectroscopic studies of swift heavy ion irradiated nanophase mullite  

Microsoft Academic Search

Photoluminescence (PL) studies of 100MeV swift Ag8+ ion bombarded combustion synthesized nanophase mullite has been studied at room temperature (RT) and the results are reported here. A pair of PL bands, one broad band centres at ?550nm and another sharp one at ?690nm are observed with excitation by a 442nm laser beam. However, when the sample is excited with 326nm

H. Nagabhushana; B. N. Lakshminarasappa; S. C. Prashantha; K. R. Nagabhushana; Fouran Singh

2006-01-01

157

Confined Dynamics in Nanophase-Separated Side Chain Polymers  

Microsoft Academic Search

The effects of constraints on the cooperative dynamics are studied in small self-assembled domains of nanophase-separated side chain polymers. In these homopolymers long alkyl groups — belonging to different monomeric units and chains — aggregate to alkyl nanodomains with a typical dimension of about 0.5–1.5nm. It is shown that a polyethylene-like glass transition (?PE) occurs within these alkyl nanodomains. This

Mario Beiner

2006-01-01

158

Ferric oxyhydroxide microparticles in water.  

PubMed

Mineralogy and specific surface area are major controls on the stabilities of ferric oxyhydroxide microparticles in natural waters. The thermodynamic stabilities of ferric oxyhydroxides, as described by the activity product in solution pK = -log [Fe(3+)] [OH(-)](3) range from pK = 37.1 for freshly precipitated amorphous oxyhydroxide to pK = 44.2 for well crystallized goethite. The sizes of suspended oxyhydroxide particles in natural waters range from less than 0.01 mum to greater than 5 mum. Oxyhydroxides precipitated in the laboratory from solutions simulating high-iron natural waters are needlelike or lathlike in shape and have mean thicknesses as small as 60 A. Large specific surface areas resulting from the small sizes of ferric oxyhydroxide particles cause increased solubilities and thus decreased pK values. Specific surface areas of 40-170 m(2)/g determined for laboratory precipitates gave computed decreases in pK of 0.4 to 1.6 units. PMID:4470932

Whittemore, D O; Langmuir, D

1974-12-01

159

Hydrogen Reduction of Ferric Ions for Use in Copper Electrowinning  

SciTech Connect

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.

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

2005-01-01

160

The role of hydrous ferric oxide precipitation in the fractionation of arsenic, gallium, and indium during the neutralization of acidic hot spring water by river water in the Tama River watershed, Japan  

NASA Astrophysics Data System (ADS)

The Obuki spring is the largest and most acidic of the Tamagawa hot springs (Akita Prefecture, northern Japan), and it discharges ca. 9000 L/min of chloride-rich acidic water (pH 1.2) that contains high concentrations of both As and rare metals such as Ga and In. This paper aims to quantify seasonal variations in the mobility of these elements in the Shibukuro and Tama rivers, which are fed by the thermal waters of the Obuki spring, caused by sorption onto hydrous ferric oxide (HFO). Seasonal observations revealed the following relationships with respect to As removal by HFO: (a) the oxidation of Fe2+ is predominantly controlled by both pH and water temperature, and progresses more quickly in less acidic and warmer conditions; (b) HFO formation was predominantly controlled by pH; and (c) the removal of dissolved arsenate is directly related to the amount of HFO present. Consequently, the oxidation to Fe3+ was slower during periods of cold and lower pH, and the amount of HFO was too small to remove the dissolved arsenate effectively. Consequently, considerable amounts of dissolved arsenate and Fe2+ remained in river water. In contrast, when HFO production from Fe3+ increased, and dissolved arsenate was removed during warmer and less acidic periods, only small amounts of dissolved arsenite and Fe2+ remained in the river water. The geochemical behavior of Ga and In was essentially controlled by pH; however, when HFO production was limited by a pH of less than 3.5, Ga behavior was controlled mainly by the amount of HFO. Gallium tended to be sorbed under more acidic conditions than was In. Due to differences in sorption behavior, Ga, As, and In were fractionated during sedimentation. In the upstream reaches, arsenate and dissolved Ga sorbed onto HFO, and were widely distributed across the watershed. Conversely, dissolved In was removed by HFO downstream. As a result, In is relatively concentrated on the downstream lakebed, unlike As and Ga, and In-rich mineral deposits are accumulating at present.

Ogawa, Yasumasa; Ishiyama, Daizo; Shikazono, Naotatsu; Iwane, Kenta; Kajiwara, Masahiro; Tsuchiya, Noriyoshi

2012-06-01

161

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

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.

Benko, B; Yu, N T

1983-01-01

162

Low temperature aqueous ferric sulfate solutions on the surface of Mars  

Microsoft Academic Search

We have studied the low-temperature properties of ferric sulfate Fe2(SO4)3 solutions as a model for potential liquid brines on the surface of Mars. Geochemical modeling demonstrates that concentrated ferric sulfate brines form through sulphur-rich acidic evaporation processes in cold oxidizing environments. Experiments and thermodynamic calculations show that the Fe2(SO4)3 eutectic temperature is 205 ± 1 K for 48 ± 2

Vincent F. Chevrier; Travis S. Altheide

2008-01-01

163

Redox reaction of artemisinin with ferrous and ferric ions in aqueous buffer.  

PubMed

Artemisinin, a sesquiterpene with endoperoxide bond, possesses potent antimalarial activity against the ring and late stage of chloroqine-resistant Plasmodium falciparum malaria both in vitro and in vivo. The mode of antimalarial activity of artemisinin is iron-dependent. The aim of this study was to investigate the reactions of artemisinin with ferrous and ferric ions in aqueous buffer. Artemisinin generated a cycle of iron oxidation and reduction. It oxidized ferrous and reduced ferric ions with similar rate of reaction (k=10+/-0.5 M(-1) x s(-1) for ferrous and k=8.5+/-2.0 M(-1) x s(-1) for ferric ion). The major active product was dihydroartemisinin which exhibited antimalarial activity at least 3 times more potent than artemisinin. Dihydroartemisinin preferably binds to ferric ion, forming ferric-dihydroartemisinin complex. The re-oxidation of the complex gives artemisinin and ferric ion. This suggests that in aqueous buffer, the reaction of artemisinin with iron may give rise to the active reaction products, one of them being dihydroartemisinin, which is responsible for antimalarial activity. PMID:11767072

Sibmooh, N; Udomsangpetch, R; Kujoa, A; Chantharaksri, U; Mankhetkorn, S

2001-12-01

164

Synthesis by vaporization-condensation and characterization of ?-Fe 2O 3, In 2O 3, SnO 2, ZnO and Zr 1?xY xO 2?? nanophases  

Microsoft Academic Search

Several nanophases have been prepared by vaporization-condensation in a solar image furnace : binary oxides such as s ?-Fe2O3, In2O3, SnO2, ZnO and ternary oxides such as Zr1?xYxO2??. The vapor-condensates have been characterized by X-ray diffraction and Transmission Electron Microscopy. Particle shapes and size distributions have been determined ; strains, structural defects have been observed. The nanostructure characteristics have been

A. Rouanet; H. Solmon; G. Pichelin; C. Roucau; F. Sibieude; C. Monty

1995-01-01

165

Hydrolysis of ferric chloride in solution  

SciTech Connect

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.

Lussiez, G.; Beckstead, L.

1996-11-01

166

An investigation of carbonaceous materials reducing ferric ions in aqueous solution  

NASA Astrophysics Data System (ADS)

By substituting the ferrous to ferric oxidation for anodic oxygen evolution in an electrowinning cell, it is possible to reduce the cell voltage by about 1 V. However, it is then necessary to reduce the ferric back to ferrous and, depending on the circumstances, acid needs to be cogenerated. Various possible reductants are discussed, and experiments are described on the use of lignite and other carbonaceous materials to reduce the ferric ion. It was found that lignite was able to reduce the ferric ion, in situ in the electrowinning cell, but that the rate of reduction was compatible only with a maximum current density of about 40 Am-2. The efficiency was increased by periodically interrupting the current flow.

Cooke, A. V.; Chilton, J. P.; Fray, D. J.

1988-10-01

167

Fabrication, optical transmittance, and hardness of IR-transparent ceramics made from nanophase yttria  

Microsoft Academic Search

Commercially available nanophase yttria powder was used to fabricate a transparent ceramic and its optical transmittance and hardness were measured. The nanophase yttria powder was dry-pressed without the use of any binders. Subsequently, the green body was sintered in air, hot-isostatically pressed, and polished, resulting in an IR-transparent ceramic. Scanning electron microscopy revealed a grain size of 21.5±11.1?m. Optical transmittance

Hergen Eilers

2007-01-01

168

Synthesis, consolidation, and mechanical testing of nanophase metals  

NASA Astrophysics Data System (ADS)

Nanophase materials possess a grain size on the order of nanometers. Due to the large volume fraction of grain boundaries in nanophase materials, it is expected that the mechanical properties of nanophase materials will be different from their conventional microcrystalline counterparts. For this study, nanocrystalline copper and palladium powders were produced by vapor condensation, and titanium aluminide powder was produced by high energy ball milling. The powders produced by both techniques were characterized, and then the powders were consolidated to provide specimens for mechanical testing. Sinterforging experiments were performed on low relative density Ti-48Al specimens to observe creep behavior and to densify green compacts. An activation energy of 328kJ/mol and an average stress exponent of 4.0 were determined from these experiments for a temperature range of 600-650sp°C. The stress exponent values remained essentially invariant with temperature, initial sample densities, and deformation history used in this study. Although grain boundary sliding was the anticipated creep mechanism due to the high volume fraction of grain boundaries in the material, both the stress exponent and the activation energy indicate power law creep. In addition, it was possible to produce a nearly dense specimen at a relatively low temperature of 700sp°C. Indentation creep experiments were performed on nanocrystalline copper and palladium specimens and also on sinterforged Ti-48Al specimens. The copper and palladium specimens showed a higher creep rate than their microcrystalline counterparts, exhibiting creep even at room temperature. The activation energies for both specimens are lower than activation energy for grain boundary diffusion in microcrystalline materials. A model is proposed to explain the higher creep rate. It assumes that the specimens produced from vapor condensed powders have a higher grain boundary energy due to a higher disorder in their grain boundary structure. Contrary to the pure metal specimens, the sinterforged Ti-48Al specimens exhibited an activation energy close to that for lattice diffusion in the microcrystalline alloy and also the activation energy determined from the sinterforging experiments.

Kim, Lisa Sungwoon

169

A purple acidophilic di-ferric DNA ligase from Ferroplasma  

PubMed Central

We describe here an extraordinary purple-colored DNA ligase, LigFa, from the acidophilic ferrous iron-oxidizing archaeon Ferroplasma acidiphilum, a di-ferric enzyme with an extremely low pH activity optimum. Unlike any other DNA ligase studied to date, LigFa contains two Fe3+-tyrosinate centers and lacks any requirement for either Mg2+ or K+ for activity. DNA ligases from closest phylogenetic and ecophysiological relatives have normal pH optima (6.0–7.5), lack iron, and require Mg2+/K+ for activity. Ferric iron retention is pH-dependent, with release resulting in partial protein unfolding and loss of activity. Reduction of the Fe3+ to Fe2+ results in an 80% decrease in DNA substrate binding and an increase in the pH activity optimum to 5.0. DNA binding induces significant conformational change around the iron site(s), suggesting that the ferric irons of LigFa act both as structure organizing and stabilizing elements and as Lewis acids facilitating DNA binding at low pH.

Ferrer, Manuel; Golyshina, Olga V.; Beloqui, Ana; Bottger, Lars H.; Andreu, Jose M.; Polaina, Julio; De Lacey, Antonio L.; Trautwein, Alfred X.; Timmis, Kenneth N.; Golyshin, Peter N.

2008-01-01

170

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

Microsoft Academic Search

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\\u000a reduces Fe(III)-chelates to Fe(II), which is subsequently taken up by the cell. Previous work has demonstrated that synthetic\\u000a chelators both support ferric reductase activity (when supplied as Fe(III)-chelates) and inhibit ferric reductase. In the

Mathew B. Sonier; Harold G. Weger

2010-01-01

171

21 CFR 73.2299 - Ferric ferrocyanide.  

Code of Federal Regulations, 2013 CFR

...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...

2013-04-01

172

High Strain Rate Response of Sandwich Composites with Nanophased Cores  

NASA Astrophysics Data System (ADS)

Polyurethane foam materials have been used as core materials in a sandwich construction with S2-Glass/SC-15 facings. The foam material has been manufactured from liquid polymer precursors of polyurethane. The precursors are made of two components; part-A (diphenylmethane diisocyanate) and part-B (polyol). In one set of experiments, part-A was mixed with part-B to manufacture the foam. In another set, TiO2 nanoparticles have been dispersed in part-A through ultrasonic cavitation technique. The loading of nanoparticles was 3% by weight of the total polymer precursor. The TiO2 nanoparticles were spherical in shape, and were about 29 nm in diameter. Sonic cavitation was carried out with a vibrasound liquid processor at 20 kHz frequency with a power intensity of about 100 kW/m2. The two categories of foams manufactured in this manner were termed as neat and nanophased. Sandwich composites were then fabricated using these two categories of core materials using a co-injection resin transfer molding (CIRTM) technique. Test samples extracted from the panel were subjected to quasi-static as well as high strain rate loadings. Rate of loading varied from 0.002 s-1 to around 1300 s-1. It has been observed that infusion of nanoparticles had a direct correlation with the cell geometry. The cell dimensions increased by about 46% with particle infusion suggesting that nanoparticles might have worked as catalysts during the foaming process. Correspondingly, enhancement in thermal properties was also noticed especially in the TGA experiments. There was also a significant improvement in mechanical properties due to nanoparticle infusion. Average increase in sandwich strength and energy absorption with nanophased cores was between 40 60% over their neat counterparts. Details of manufacturing and analyses of thermal and mechanical tests are presented in this paper.

Mahfuz, Hassan; Uddin, Mohammed F.; Rangari, Vijaya K.; Saha, Mrinal C.; Zainuddin, Shaik; Jeelani, Shaik

2005-05-01

173

X-ray absorption spectroscopic study of the sorption of Cr(III) at the oxide-water interface II. Adsorption, coprecipitation, and surface precipitation on hydrous ferric oxide  

Microsoft Academic Search

The sorption of Cr(III) by hydrous Fe oxides involves adsorption, surface precipitation, and copre- cipitation phenomena. These phenomena lead to different phases which are here compared with regard to both their Cr solubility and their local structure. The former is simulated by the \\

LAURENT CHARLET; ALAIN A. MANCEAU

1992-01-01

174

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

PubMed

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(H(2)O)(6)](3+). Mobilizing this iron requires bio-ferrireduction which in turn requires managing the rapid autoxidation of the resulting Fe(II) 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 Fe(III) and the ROS-generating autoxidation of Fe(II) so as to make this metal ion available as the most ubiquitous prosthetic group in metallobiology. PMID:23264695

Kosman, Daniel J

2013-01-01

175

21 CFR 582.5306 - Ferric sodium pyrophosphate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5306 Ferric sodium pyrophosphate. (a) Product. Ferric sodium...

2013-04-01

176

21 CFR 73.1298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Ferric ammonium ferrocyanide. 73.1298 Section 73.1298 Food and Drugs FOOD AND DRUG ADMINISTRATION...ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1298 Ferric ammonium ferrocyanide. (a)...

2010-04-01

177

21 CFR 73.1298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Ferric ammonium ferrocyanide. 73.1298 Section 73.1298 Food and Drugs FOOD AND DRUG ADMINISTRATION...ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1298 Ferric ammonium ferrocyanide. (a)...

2009-04-01

178

Arsenic Removal from Groundwater using Ferric  

Microsoft Academic Search

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

R. G. Fernandez; B. Petrusevski

179

Design, synthesis, and evaluation of nanophase ceramics for orthopaedic/dental applications  

NASA Astrophysics Data System (ADS)

Clinical complications with conventional orthopaedic/dental implant devices are often due to insufficient bonding to juxtaposed bone; osseointegration provides mechanical stability to prostheses in situ , minimizes motion induced damage to surrounding tissues and is crucial to the clinical success of orthopaedic/dental implants. Ceramics have long been appreciated for their biocompatibility with bone cells and tissue, but, poor mechanical properties (such as ductility) have limited their wide use as orthopaedic/dental implants. The objective of the present in vitro study was to investigate, for the first time, various properties of nanophase (that is, novel material formulations with grain and pore sizes less than 100 nm) ceramics pertinent to orthopaedic/dental applications. Compared to conventional (that is, grain sizes greater than 100 nm) formulations of the same material, nanophase ceramics possess attractive mechanical and cytocompatibility properties. Specifically, nanophase ceramics demonstrated bending properties on the same order of magnitude as physiological bone; such properties are highly desirable for materials used as bone implants. Most important, the functions (such as adhesion, proliferation, synthesis of alkaline phosphatase, and deposition of calcium-containing mineral) of osteoblasts (the bone-forming cells) were selectively and significantly enhanced on nanophase ceramics. These results are most remarkable when contrasted to the observed decreased adhesion of fibroblasts (cells that contribute to fibrous encapsulation and callus formation events that lead to implant loosening and failure) on the nanophase alumina, titania, and hydroxyapatite tested. Investigation of the mechanism(s) of the observed, select, enhanced osteoblast adhesion (a crucial prerequisite for subsequent, anchorage-dependent-cell function) on all ceramic formulations tested in the present study revealed that the concentration, conformation, and bioactivity of vitronectin were important parameters mediating osteoblast adhesion exclusively on nanoceramics. Conformation of vitronectin that exposed epitopes (such as integrin-binding and heparan sulfate-binding sites) necessary for subsequent select osteoblast adhesion was enhanced on nanophase ceramics; these material formulations also promoted calcium and, subsequent, calcium-mediated vitronectin adsorption. By demonstrating that bioceramics can be designed and fabricated (through control of grain and pore size) to possess improved cytocompatibility properties for select osteoblast function, the results of the present study have made fundamental and groundbreaking contributions to the emerging fields of cellular/tissue engineering and nanophase material science. Undoubtedly, as this study demonstrated for the first time, nanophase ceramics have great potential to become the next generation, choice orthopaedic/dental biomaterial to enhance bonding to juxtaposed bone and, thus, increase implant efficacy.

Webster, Thomas Jay

180

Modeling ferrous ferric iron chemistry with application to martian surface geochemistry  

NASA Astrophysics Data System (ADS)

The Mars Global Surveyor, Mars Exploration Rover, and Mars Express missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major recent mission findings are the presence of jarosite (a ferric sulfate salt), which requires formation from an acid-sulfate brine, and the occurrence of hematite and goethite on Mars. Recent ferric iron models have largely focused on 25 °C, which is a major limitation for models exploring the geochemical history of cold bodies such as Mars. Until recently, our work on low-temperature iron-bearing brines involved ferrous but not ferric iron, also obviously a limitation. The objectives of this work were to (1) add ferric iron chemistry to an existing ferrous iron model (FREZCHEM), (2) extend this ferrous/ferric iron geochemical model to lower temperatures (<0 °C), and (3) use the reformulated model to explore ferrous/ferric iron chemistries on Mars. The FREZCHEM model is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions using the Pitzer approach for the temperature range from <-70 to 25 °C and the pressure range from 1 to 1000 bars. Ferric chloride and sulfate mineral parameterizations were based, in part, on experimental data. Ferric oxide/hydroxide mineral parameterizations were based exclusively on Gibbs free energy and enthalpy data. New iron parameterizations added 23 new ferrous/ferric minerals to the model for this Na-K-Mg-Ca-Fe(II)-Fe(III)-H-Cl-SO 4-NO 3-OH-HCO 3-CO 3-CO 2-O 2-CH 4-H 2O system. The model was used to develop paragenetic sequences for Rio Tinto waters on Earth and a hypothetical Martian brine derived from acid weathering of basaltic minerals. In general, model simulations were in agreement with field evidence on Earth and Mars in predicting precipitation of stable iron minerals such as jarosites, goethite, and hematite. In addition, paragenetic simulations for Mars suggest that other iron minerals such as lepidocrocite, schwertmannite, ferricopiapite, copiapite, and bilinite may also be present on the surface of Mars. Evaporation or freezing of the Martian brine led to similar mineral precipitates. However, in freezing, compared to evaporation, the following key differences were found: (1) magnesium sulfates had higher hydration states; (2) there was greater total aqueous sulfate (SO 4T = SO 4 + HSO 4) removal; and (3) there was a significantly higher aqueous Cl/SO 4T ratio in the residual Na-Mg-Cl brine. Given the similarities of model results to observations, alternating dry/wet and freeze/thaw cycles and brine migration could have played major roles in vug formation, Cl stratification, and hematite concretion formation on Mars.

Marion, Giles M.; Kargel, Jeffrey S.; Catling, David C.

2008-01-01

181

Simulation of nanophase iron production in lunar space weathering  

NASA Astrophysics Data System (ADS)

Nanophase iron (np-Fe0) particles produced by space weathering have been widely observed in lunar soil. Current research suggests that np-Fe0 could have important effects on the chemical, optical and magnetic properties of the lunar soil. To investigate the relationship between np-Fe0 and these properties of lunar soil, simulation of the production process of np-Fe0 by space weathering is necessary because of the scarcity of lunar samples for research purposes. New methods using microwave heating and magnetron sputtering techniques to simulate np-Fe0 production both in the glass phase and on the grain surfaces, respectively, are investigated in this study. Both the formation and occurrence of np-Fe0 are taken into account in the experiment. The X-ray Diffraction (XRD) spectra show that metallic iron has formed in the glass phase produced by microwave heating of ilmenite. Using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), the size of np-Fe0 particles produced in a microwave heating experiment, which is held for 8 min at 1300 °C, is determined to be about 100-500 nm. Compared to the glass of lunar sample 10084, the major composition of the glass matrix is formed by microwave heating compares favorably. In magnetron sputtering experiment the size of np-Fe0 particles is about 20-30 nm, and appears on the grain surfaces. The characteristics of np-Fe0 produced in the simulations are consistent with those of lunar samples documented in the literature.

Tang, Hong; Wang, Shijie; Li, Xiongyao

2012-01-01

182

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

PubMed

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

Sonier, Mathew B; Weger, Harold G

2010-05-29

183

Small-angle neutron-scattering study of nanophase zirconia in a reverse micelle synthesis.  

National Technical Information Service (NTIS)

Nanophase zirconia particles are synthesized by mixing two reverse micelle solutions containing the precursor salt ZrOCl(sub 2) and the base NH(sub 4)OH. The primary reverse micelle solution consists of AOT, toluene and water. The reverse micelle structur...

G. A. Lager X. Li C. K. Loong R. Miranda P. Thiyagarajan

1999-01-01

184

Structure and magnetic properties of mechanically-alloyed SmZr(CoFe) nanophase hard magnets  

Microsoft Academic Search

Summary form only given. In the recent search for new high temperature permanent magnetic materials, research has concentrated on bulk Sm2Co17 type magnets. The usual approach to development of coercivity in these bulk materials is to prepare a nanophase cellular microstructure with cell walls which act as pinning sites. In this work, a systematic investigation of structural and magnetic properties

K. Gallagher; A. le Gouil; M. Venkatesan; J. M. D. Coey

2002-01-01

185

Ferric ions inhibit proteolytic processing of progastrin  

PubMed Central

The gastrointestinal hormone gastrin is generated from an 80 amino acid precursor (progastrin) by cleavage after dibasic residues by prohormone convertase 1. Phosphorylation of Ser75 has previously been suggested, on the basis of indirect evidence, to inhibit cleavage of progastrin after Arg73Arg74. Gastrins bind two ferric ions with high affinity, and iron binding is essential for the biological activity of non-amidated gastrins in vitro and in vivo. This study directly investigated the effect of iron binding and of serine phosphorylation on the cleavage of synthetic progastrin-derived peptides. The affinity of synthetic progastrin55-80 for ferric ions, and the rate of cleavage by prohormone convertase 1, were not affected by phosphorylation of Ser75. In contrast, in the presence of ferric ions the rate of cleavage of both progastrin55-80 and phosphoSer75progastrin55-80 by prohormone convertase 1 was significantly reduced. Hence iron binding to progastrin may regulate processing and secretion in vivo, and regulation may be particularly important in diseases with altered iron homeostasis.

Bramante, Gianni; Patel, Oneel; Shulkes, Arthur; Baldwin, Graham S.

2011-01-01

186

Nanophase hydroxyapatite coatings for dental and orthopedic applications  

NASA Astrophysics Data System (ADS)

In order to improve dental and orthopedic implant performance, the objective of this study was to synthesize nanocrystalline hydroxyapatite (HA) powders to coat metals (specifically, titanium and tantalum). Precipitated HA powders were either sintered in order to produce UltraCaP HA (or microcrystalline size HA) or were treated hydrothermally to produce nanocrystalline HA. Some of the UltraCaP and nanocrystalline HA powders were doped with yttrium (Y) since previous in vitro studies demonstrated that Y-doped HA in bulk improved osteoblast (or bone-forming cell) function over undoped HA. The nanocrystalline HA powders were also mixed with nanophase titania powders because previous studies demonstrated that titania/HA composite coatings increased coating adhesive strength and HA nucleation. These powders were then deposited onto titanium by a novel room-temperature process, called IonTiteT(TM). The results demonstrated that the chemical properties and crystallite size of the original HA powders were maintained in the coatings. More importantly, in vitro studies showed increased osteoblast (bone-forming cell) adhesion on the single phase nanocrystalline HA and nano-titania/HA coatings compared to traditionally used plasma-sprayed HA coatings and uncoated metals. Results further demonstrated greater amounts of calcium deposition by osteoblasts cultured on nanocrystalline HA coatings compared to UltraCaP coatings and conventionally used plasma-sprayed HA coatings. To elucidate mechanisms that influenced osteoblast functions on the HA coatings, the amount of proteins (fibronectin and vitronectin) onto the HA powders and the adsorbed fibronectin conformation were investigated. Exposure of cell integrin binding domains (in fibronectin III10 segments) was greater in fibronectin adsorbed onto 1.2 mole% Y-doped UltraCaP HA coatings compared to nanocrystalline HA coatings tested. However, 1.2 mole% Y-doped UltraCaP HA coatings did not increase mineralization by osteoblasts compared to the nanocrystalline HA coatings. These results suggested that the availability of integrin binding domains in fibronectin did not correlate to enhanced mineralization by osteoblasts on nanocrystalline HA coatings. Lastly, undoped nanocrystalline HA coatings were studied using a well-established rat calvaria in vivo. Histological analysis showed that nanocrystalline HA coated on tantalum scaffolds increased bone and fibrous tissue infiltration into the scaffolds while uncoated and UltraCaP HA coated scaffolds did not after as early as 6 weeks. In summary, these results encourage further studies on nanocrystalline IonTiteTM HA coatings on various metals for orthopedic and dental applications.

Sato, Michiko

187

Carbothermic reaction process for making nanophase WC-Co powders  

SciTech Connect

A carbothermic reaction process is described for the production of nanophase metal/metal carbide particles comprised of the steps of: (a) preparing porous precursor particles by partial or full chemical reduction, the porous precursor powders acting as substrates for carbon infiltration, the preparation of precursor powder being effected by subjecting a solution of metal ions prepared from tungsten or cobalt compounds to a drying treatment selected from the group consisting of: spray calcining, spray roasting, spray drying, or freeze drying; (b) infiltrating the porous precursor particles with amorphous carbon from a carbon source gas or gas mixture at a carbon activity greater than or equal to 1.0, said carbon source gas being selected from the group consisting of CO, CO/CO[sub 2], CH[sub 4]/H[sub 2], and combinations thereof capable of achieving carbon deposition; said infiltrating of the porous precursor powders being achieved using low temperature catalytic decomposition of the selected gas or gas mixture by the precursor powder particle substrate; (c) simultaneously reacting the carbon from the source gas with the porous precursor powder particle substrates to form at least one carbide phase; (d) removing remaining unreacted carbon by gasification using a gas or gas mixture of carbon activity less than 1.0, the gas or gas mixture being selected from the group consisting of CO[sub 2], CO/CO[sub 2], CH[sub 4]/H[sub 2], or combinations thereof capable of removing carbon; said infiltrating and removing process steps being effected in a tube furnace, a muffle furnace, a belt furnace, a rotary kiln, a fluid bed furnace, or furnace suited for heating the precursor powder and gases to temperatures up to 1,000 C and achieving infiltration of carbon from a carbon source gas at a carbon activity greater than or equal to 1.0 and removal of unreacted carbon by gasification using a gas or gas mixture having a carbon activity less than 1.0.

McCandlish, E.; Kear, B.H.; Byoungkee Kim.

1993-07-27

188

Increased osteoblast adhesion on nanophase metals: Ti, Ti6Al4V, and CoCrMo  

Microsoft Academic Search

Previous studies have demonstrated increased functions of osteoblasts (bone-forming cells) on nanophase compared to conventional ceramics (specifically, alumina, titania, and hydroxyapatite), polymers (such as poly lactic-glycolic acid and polyurethane), carbon nanofibers\\/nanotubes, and composites thereof. Nanophase materials are unique materials that simulate dimensions of constituent components of bone since they possess particle or grain sizes less than 100nm. However, to date,

Thomas J. Webster; Jeremiah U. Ejiofor

2004-01-01

189

Ferric Chloride-Catalyzed Activation of Hydrogen Peroxide for the Demethylation of N, N-dimethylaniline, the Epoxidation of Olefins, and the Oxidative Cleavage of Vicinal Diols in Acetonitrile: A Reaction Mimic for Cytochrome P-450  

Microsoft Academic Search

In dry acetonitrile, anhydrous FeIIICl3 catalyzes the demethylation of N,N-dimethylaniline, the epoxidation of olefins, and the oxidative cleavage of 1-phenyl-1,2-ethanediol (and other 1,2-diols) by hydrogen peroxide. For each class of substrate the products closely parallel those that result from their enzymatic oxidation by cytochrome P-450. Because of (i) the close congruence of products, (ii) the catalytic nature of the FeIIICl3\\/H2O2

Hiroshi Sugimoto; Lee Spencer; Donald T. Sawyer

1987-01-01

190

Rapid Assay for Microbially Reducible Ferric Iron in Aquatic Sediments  

PubMed Central

The availability of ferric iron for microbial reduction as directly determined by the activity of iron-reducing organisms was compared with its availability as determined by a newly developed chemical assay for microbially reducible iron. The chemical assay was based on the reduction of poorly crystalline ferric iron by hydroxylamine under acidic conditions. There was a strong correlation between the extent to which hydroxylamine could reduce various synthetic ferric iron forms and the susceptibility of the iron to microbial reduction in an enrichment culture of iron-reducing organisms. When sediments that contained hydroxylamine-reducible ferric iron were incubated under anaerobic conditions, ferrous iron accumulated as the concentration of hydroxylamine-reducible ferric iron declined over time. Ferrous iron production stopped as soon as the hydroxylamine-reducible ferric iron was depleted. In anaerobic incubations of reduced sediments that did not contain hydroxylamine-reducible ferric iron, there was no microbial iron reduction, even though the sediments contained high concentrations of oxalate-extractable ferric iron. A correspondence between the presence of hydroxylamine-reducible ferric iron and the extent of ferric iron reduction in anaerobic incubations was observed in sediments from an aquifer and in fresh- and brackish-water sediments from the Potomac River estuary. The assay is a significant improvement over previously described procedures for the determination of hydroxylamine-reducible ferric iron because it provides a correction for the high concentrations of solid ferrous iron which may also be extracted from sediments with acid. This is a rapid, simple technique to determine whether ferric iron is available for microbial reduction.

Lovley, Derek R.; Phillips, Elizabeth J. P.

1987-01-01

191

Rapid assay for microbially reducible ferric iron in aquatic sediments.  

PubMed

The availability of ferric iron for microbial reduction as directly determined by the activity of iron-reducing organisms was compared with its availability as determined by a newly developed chemical assay for microbially reducible iron. The chemical assay was based on the reduction of poorly crystalline ferric iron by hydroxylamine under acidic conditions. There was a strong correlation between the extent to which hydroxylamine could reduce various synthetic ferric iron forms and the susceptibility of the iron to microbial reduction in an enrichment culture of iron-reducing organisms. When sediments that contained hydroxylamine-reducible ferric iron were incubated under anaerobic conditions, ferrous iron accumulated as the concentration of hydroxylamine-reducible ferric iron declined over time. Ferrous iron production stopped as soon as the hydroxylamine-reducible ferric iron was depleted. In anaerobic incubations of reduced sediments that did not contain hydroxylamine-reducible ferric iron, there was no microbial iron reduction, even though the sediments contained high concentrations of oxalate-extractable ferric iron. A correspondence between the presence of hydroxylamine-reducible ferric iron and the extent of ferric iron reduction in anaerobic incubations was observed in sediments from an aquifer and in fresh- and brackish-water sediments from the Potomac River estuary. The assay is a significant improvement over previously described procedures for the determination of hydroxylamine-reducible ferric iron because it provides a correction for the high concentrations of solid ferrous iron which may also be extracted from sediments with acid. This is a rapid, simple technique to determine whether ferric iron is available for microbial reduction. PMID:16347384

Lovley, D R; Phillips, E J

1987-07-01

192

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

PubMed

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

Lee, Jung-Pil; Choi, Sinho; Park, Soojin

2012-08-08

193

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

PubMed Central

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.

2012-01-01

194

Shewanella spp. Use Acetate as an Electron Donor for Denitrification but Not Ferric Iron or Fumarate Reduction  

PubMed Central

Lactate but not acetate oxidation was reported to support electron acceptor reduction by Shewanella spp. under anoxic conditions. We demonstrate that the denitrifiers Shewanella loihica strain PV-4 and Shewanella denitrificans OS217 utilize acetate as an electron donor for denitrification but not for fumarate or ferric iron reduction.

Yoon, Sukhwan; Sanford, Robert A.

2013-01-01

195

Ultrasound Driven Deposition and Reactivity of Nanophasic Amorphous Iron Clusters with Surface Silanols of Submicrospherical Silica  

Microsoft Academic Search

Aggregates of nanophasic amorphous iron particles in the size range of 5-10 nm have been deposited on Stober's silica submicrospheres exhibiting varying degrees of surface reactivity, by an ultrasound-driven decomposition of iron pentacarbonyl in Decalin medium. The reaction of the surface-active species such as adsorbed water, silanols, and the bridging oxygens of the strained siloxane links with elemental iron and

Sivarajan Ramesh; Ruslan Prozorov; Aharon Gedanken

1997-01-01

196

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

NASA Astrophysics Data System (ADS)

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.

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

2000-10-01

197

Characterization of micro- and nanophase separation of dentin bonding agents by stereoscopy and atomic force microscopy.  

PubMed

The aim was to study the effect of solvents on the phase separation of four commercial dental adhesives. Four materials were tested: Clearfil™ SE Bond (CSE), Clearfil Protect Bond (CPB), Clearfil S3 Bond (CS3), and One-Up Bond F Plus (OUB). Distilled water or ethanol was used as a solvent (30 vol%) for microphase separation studies, by stereoscopy. For nanophase images, the mixtures were formulated with two different solvent concentrations (2.5 versus 5 vol%) and observed by atomic force microscopy. Images were analyzed by using MacBiophotonics ImageJ to measure the area of bright domains. Macrophase separations, identified as a loss of clarity, were only observed after mixing the adhesives with water. Nanophase separations were detected with all adhesive combinations. The area of bright domains ranged from 132 to 1,145 nm² for CSE, from 15 to 285 nm² for CPB, from 149 to 380 nm² for CS3, and from 26 to 157 nm² for OUB. In water-resins mixtures, CPB was the most homogeneous and OUB showed the most heterogeneous phase formation. In ethanol-resin mixtures, CSE attained the most homogeneous structure and OUB showed the most heterogeneous phase. Addition of 5 vol% ethanol to resins decreased the nanophase separation when compared with the control materials. PMID:22300801

Toledano, Manuel; Yamauti, Monica; Osorio, Estrella; Monticelli, Francesca; Osorio, Raquel

2012-02-03

198

46 CFR 151.50-75 - Ferric chloride solution.  

Code of Federal Regulations, 2011 CFR

...Shipping 5 2011-10-01 2011-10-01 false Ferric chloride solution. 151.50-75 Section 151.50-75 Shipping...MATERIAL CARGOES Special Requirements § 151.50-75 Ferric chloride solution. A containment system (cargo tank...

2011-10-01

199

40 CFR 415.380 - Applicability; description of the ferric chloride production subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the ferric chloride production subcategory. 415.380...MANUFACTURING POINT SOURCE CATEGORY Ferric Chloride Production Subcategory § 415.380 Applicability; description of the ferric chloride production subcategory. The...

2010-07-01

200

Energy transduction by anaerobic ferric iron respiration in Thiobacillus ferrooxidans  

SciTech Connect

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 by starved cells did not occur in the absence of an electron donor, neither under aerobic conditions nor under anaerobic conditions. Uptake of glycine could be driven by formate- and ferrous iron-dependent oxygen uptake. Under anaerobic conditions, ferric iron respiration with the electron donors formate and elemental sulfur could energize glycine uptake. Glycine uptake was inhibited by the uncoupler 2,4-dinitrophenol. The results indicate that anaerobic ferric iron respiration can contribute to the energy budget of T. ferrooxidans.

Pronk, J.T.; Liem, K.; Bos, P.; Kuenen, J.G. (Delft Univ. of Technology (Netherlands))

1991-07-01

201

Anacardic acids and ferric ion chelation.  

PubMed

6-Pentadeca(e)nylsalicylic acids isolated from the cashew Anacardium occidentale L. (Anacardiaceae), commonly known as anacardic acids, inhibited the linoleic acid peroxidation catalyzed by soybean lipoxygenase-1 (EC 1.13.11.12, type 1) competitively without prooxidant effects. Their parent compound, salicylic acid, did not have this inhibitory activity up to 800 pm, indicating that the pentadeca(e)nyl group is an essential element to elicit the activity. The inhibition is attributed to its ability to chelate iron in the enzyme. Thus, anacardic acids chelate iron in the active site of the enzyme and then the hydrophobic tail portion slowly begins to interact with the hydrophobic domain close to the active site. Formation of the anacardic acids-ferric ion complex was detected in the ratio of 2:1 as the base peak in the negative ion electrospray ionization mass spectrometry. Hence, anacardic acids inhibit both Eox and Ered forms. PMID:18069245

Tsujimoto, Kazuo; Hayashi, Akio; Ha, Tae Joung; Kubo, Isao

202

Ferric chloride-catalyzed activation of hydrogen peroxide for the demethylation of N,N-dimethylaniline, the epoxidation of olefins, and the oxidative cleavage of vicinal diols in acetonitrile: a reaction mimic for cytochrome P-450.  

PubMed Central

In dry acetonitrile, anhydrous Fe(III)Cl3 catalyzes the demethylation of N,N-dimethylaniline, the epoxidation of olefins, and the oxidative cleavage of 1-phenyl-1,2-ethanediol (and other 1,2-diols) by hydrogen peroxide. For each class of substrate the products closely parallel those that result from their enzymatic oxidation by cytochrome P-450. Because of the close congruence of products, the catalytic nature of the Fe(III)Cl3/H2O2 reaction mimic, and the similarity of the dipolar aprotic solvent (acetonitrile) to the proteinaceous lipid matrix of the biomembrane, the form of the reactive intermediate may be the same in each case. A mechanism is proposed in which an initial Lewis acid-base interaction of Fe(III)Cl3 with H2O2 generates a highly electrophilic Fe(III)-oxene species as the reactive intermediate. This is in contrast to the prevailing view that cytochrome P-450 acts as a redox catalyst to generate an Fe(V)-oxo species or an Fe(IV)-oxo cation radical as the reactive intermediate.

Sugimoto, H; Spencer, L; Sawyer, D T

1987-01-01

203

Ferric chloride-catalyzed activation of hydrogen peroxide for the demethylation of N,N-dimethylaniline, the epoxidation of olefins, and the oxidative cleavage of vicinal diols in acetonitrile: a reaction mimic for cytochrome P-450.  

PubMed

In dry acetonitrile, anhydrous Fe(III)Cl3 catalyzes the demethylation of N,N-dimethylaniline, the epoxidation of olefins, and the oxidative cleavage of 1-phenyl-1,2-ethanediol (and other 1,2-diols) by hydrogen peroxide. For each class of substrate the products closely parallel those that result from their enzymatic oxidation by cytochrome P-450. Because of the close congruence of products, the catalytic nature of the Fe(III)Cl3/H2O2 reaction mimic, and the similarity of the dipolar aprotic solvent (acetonitrile) to the proteinaceous lipid matrix of the biomembrane, the form of the reactive intermediate may be the same in each case. A mechanism is proposed in which an initial Lewis acid-base interaction of Fe(III)Cl3 with H2O2 generates a highly electrophilic Fe(III)-oxene species as the reactive intermediate. This is in contrast to the prevailing view that cytochrome P-450 acts as a redox catalyst to generate an Fe(V)-oxo species or an Fe(IV)-oxo cation radical as the reactive intermediate. PMID:3470755

Sugimoto, H; Spencer, L; Sawyer, D T

1987-04-01

204

Carbothermally prepared nanophase SiC/Si{sub 3}N{sub 4} composite powders and densified parts  

SciTech Connect

Nanophase SiC/Si{sub 3}N{sub 4} composite powders were synthesized by the carbothermal nitridation of SiO{sub 2}. These powders have desirable characteristics of high quality with oxygen contents on the order of 1.5 to 2 wt. %, surface area of {approximately}10 m{sup 2}/g, submicron {alpha}-Si{sub 3}N{sub 4}, low metallic impurity levels, and a homogeneous distribution of the nanophase SiC phase. High-resolution TEM analysis has shown that the content and size of the nanophase SiC can be varied from 0.5 to 50 wt. and 25 to 500 nm, respectively, through proper control of raw materials and reactor conditions. To determine how the nanophase SiC reinforcement affects the mechanical properties of Si{sub 3}N{sub 4}, densified components were fabricated using both pressureless and pressure-assisted densification methods. TEM analysis revealed that the nanophase SiC particles are distributed both intergranularly and intragranularly throughout the Si{sub 3}N{sub 4} matrix. By controlling the sintering additive package and the sintering conditions, the ratio of inter- to intragranular SiC can be adjusted. Mechanical property measurements at elevated temperatures showed a dramatic improvement in high-temperature strength and creep resistance over components made with commercially available powders.

Carroll, D.F.; Weimer, A.W.; Dunmead, S.D.; Eisman, G.A.; Hwang, J.H.; Cochran, G.A.; Susnitzky, D.W.; Beaman, D.R.; Conner, C.L. [Dow Chemical Co., Midland, MI (United States). Ceramics and Advanced Materials Research

1997-12-31

205

Effect of gallic acid on renal biochemical alterations in male Wistar rats induced by ferric nitriloacetic acid  

Microsoft Academic Search

The present study is an effort to identify a potent chemopreventive agent against various diseases (including cancer) in which oxidative stress and cell proliferation plays an important causative role. This study was designed to investigate the effect of gallic acid against ferric nitrilotriacetic acid (Fe-NTA)-induced carcinogen\\/drug metabolizing phase I and phase II enzymes, anti-oxidative parameters, kidney markers, tumour promotion markers

Lakshmi Prasad; Tajdar Husain Khan; Tamanna Jahangir; Sarwat Sultana

2006-01-01

206

Kinetics of galena dissolution in ferric chloride solutions  

NASA Astrophysics Data System (ADS)

A leaching investigation of galena with ferric chloride has been carried out as a function of concentration of ferric chloride and sodium chloride, temperature, and particle size. Three size fractions were considered in this investigation, namely, 48 × 65, 35 × 48, and 28 × 35 mesh. The concentration ranges of ferric chloride and sodium chloride used in this investigation were 0 to 0.25 M and 0 to 3 M, respectively. The reaction rate mechanism has been discussed in terms of a shrinking core model developed for cubic systems. Mass transport of ferric chlorocomplex through the product sulfur layer appears to be responsible for establishing the overall leaching rate under most of the conditions used in this investigation. The apparent activation energy for the leaching of 28 × 35 mesh galena with 0.1 M FeCl3, 1 M HC1, and 3.0 M NaCl was found to be about 8.05 kcal/mol (33.7 kJ/mol), which was partially contributed by diffusion and partially by the heat of reaction of the formation of ferric chlorocomplexes. Rate of dissolution at both 50° and 90 °C is greatly affected by ferric chloride concentration up to 0.2 M and is essentially constant with ferric chloride concentration above this value.

Fuerstenau, M. C.; Chen, C. C.; Han, K. N.; Palmer, B. R.

1986-09-01

207

Presence of an iron-rich nanophase material in the upper layer of the Cretaceous-Tertiary boundary clay  

NASA Astrophysics Data System (ADS)

We report new geochemical evidence from ten Cretaceous-Tertiary boundary sites in North America and Europe, indicating the presence of a material remnant of a large asteroid or comet that struck the Earth at 65.0 Ma. Mössbauer spectroscopic data reveals that a ubiquitous iron-rich nanophase material exists at the uppermost part of the K-T boundary layer in the Western Hemisphere and in Europe in marine and continental fine-grained sedimentary rock. The high surface-to-volume ratio of nanophase material suggests that it may be the carrier of the iridium abundance enhancement that marks the K-T boundary. Even more provocative is the possibility that the discovered nanophase material is, for the most part, composed of the vaporized impactor after the impact-generated high-temperature vapor plume rose and cooled above the atmosphere.

Wdowiak, Thomas J.; Armendarez, Lawrence P.; Agresti, David G.; Wade, Manson L.; Wdowiak, Suzanne Y.; Claeys, Philippe; Izett, Glenn

2001-01-01

208

Immobilization of arsenite and ferric iron by Acidithiobacillus ferrooxidans and its relevance to acid mine drainage.  

PubMed

Weathering of the As-rich pyrite-rich tailings of the abandoned mining site of Carnoulès (southeastern France) results in the formation of acid waters heavily loaded with arsenic. Dissolved arsenic present in the seepage waters precipitates within a few meters from the bottom of the tailing dam in the presence of microorganisms. An Acidithiobacillus ferrooxidans strain, referred to as CC1, was isolated from the effluents. This strain was able to remove arsenic from a defined synthetic medium only when grown on ferrous iron. This A. ferrooxidans strain did not oxidize arsenite to arsenate directly or indirectly. Strain CC1 precipitated arsenic unexpectedly as arsenite but not arsenate, with ferric iron produced by its energy metabolism. Furthermore, arsenite was almost not found adsorbed on jarosite but associated with a poorly ordered schwertmannite. Arsenate is known to efficiently precipitate with ferric iron and sulfate in the form of more or less ordered schwertmannite, depending on the sulfur-to-arsenic ratio. Our data demonstrate that the coprecipitation of arsenite with schwertmannite also appears as a potential mechanism of arsenite removal in heavily contaminated acid waters. The removal of arsenite by coprecipitation with ferric iron appears to be a common property of the A. ferrooxidans species, as such a feature was observed with one private and three collection strains, one of which was the type strain. PMID:14532077

Duquesne, K; Lebrun, S; Casiot, C; Bruneel, O; Personné, J-C; Leblanc, M; Elbaz-Poulichet, F; Morin, G; Bonnefoy, V

2003-10-01

209

Fe-heme conformations in ferric myoglobin.  

PubMed Central

X-ray absorption near-edge structure (XANES) spectra of ferric myoglobin from horse heart have been acquired as a function of pH (between 5.3 and 11.3). At pH = 11.3 temperature-dependent spectra (between 20 and 293 K) have been collected as well. Experimental data solve three main conformations of the Fe-heme: the first, at low pH, is related to high-spin aquomet-myoglobin (Mb+OH2). The other two, at pH 11.3, are related to hydroxymet-myoglobin (Mb+OH-), and are in thermal equilibrium, corresponding to high- and low-spin Mb+OH-. The structure of the three Fe-heme conformations has been assigned according to spin-resolved multiple scattering simulations and fitting of the XANES data. The chemical transition between Mb+OH2 and high-spin Mb+OH-, and the spin transition of Mb+OH-, are accompanied by changes of the Fe coordination sphere due to its movement toward the heme plane, coupled to an increase of the axial asymmetry.

Longa, S D; Pin, S; Cortes, R; Soldatov, A V; Alpert, B

1998-01-01

210

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2013 CFR

...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...

2013-04-01

211

21 CFR 73.1025 - Ferric ammonium citrate.  

Code of Federal Regulations, 2013 CFR

...the following conditions: (1) The dyed suture shall conform in all respects to the requirements of the United States Pharmacopeia XX (1980). (2) The level of the ferric ammonium citrate-pyrogallol complex shall not exceed 3...

2013-04-01

212

46 CFR 151.50-75 - Ferric chloride solution.  

Code of Federal Regulations, 2012 CFR

...HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-75 Ferric chloride solution. A containment system (cargo tank piping system, venting system, and gauging system) carrying this solution must be lined with rubber,...

2012-10-01

213

The kinetics of dissolution of sphalerite in ferric chloride solution  

Microsoft Academic Search

The dissolution of sphalerite in acidic ferric chloride solution was investigated in the temperature range 320 to 360 K. Both\\u000a sized particles from three sources and polished flat surfaces were used as samples. The effect of stirring rate, temperature,\\u000a ferric and ferrous ion concentration, purity, and particle size on the dissolution rate were determined. During the initial\\u000a stages of the

G. E. Bobeck; H. Su

1985-01-01

214

New nanophase iron-based catalysts for hydrocracking applications  

Microsoft Academic Search

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

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

1994-01-01

215

Removal of terephthalic acid in alkalized wastewater by ferric chloride.  

PubMed

Terephthalic acid, which is a main component in alkali-decrement wastewater, is efficiently removed using ferric chloride in high pH solutions. About 90% removal of terephthalic acid is achieved at pH between 8 and 11. Especially, the removal reached 94.3% at pH 11. However, as the pH increased from pH 12 and 13, the low removal of terephthalic acid were found. The increasing ferric chloride dosage had a dramatic positive impact on the achieved removal of terephthalic acid. Further increase in the ferric chloride dosage did not produce better removal rate. The increase of terephthalic acid concentration also led to the increase of ferric chloride dosage in order to get the same removal of terephthalic acid. There was approximately a negative linear relationship between terephthalic acid concentration and removal of terephthalic acid. Compared with other coagulants, it can be seen that ferric chloride is more effective in a high pH solution and the amount of ferric chloride required is also less as compared with aluminum chloride, magnesium chloride and calcium chloride. Our results clearly showed that terephthalate anions strongly binds to positive Fe(OH)(3) flocs and forms insoluble complexes, probably through a mechanism involving electrostatic attraction. The electrostatic attraction may be particularly useful means of purifying wastewater in high pH solutions. PMID:16839672

Wen, Yue-Zhong; Tong, Shao-Ping; Zheng, Ke-Feng; Wang, Liao-Liao; Lv, Jin-Ze; Lin, Jun

2006-06-03

216

Ferric haem forms of Mycobacterium tuberculosis catalase-peroxidase probed by EPR spectroscopy: Their stability and interplay with pH.  

PubMed

Low temperature EPR spectroscopy was used to characterise Mycobacterium tuberculosis catalase-peroxidase in its resting ferric haem state. Several high spin ferric haem forms and no low spin forms were found in the enzyme samples frozen in methanol on dry ice. The EPR spectra depended not only on the pH but also on the buffer type. As a general trend, the higher the pH, the greater the 'rhombic' fraction of the high spin ferric haem that was observed. The rhombic form was characterised by well separated two lines in the g = 6 region whereas in the 'axial' form the two lines overlap. This pH dependence of the equilibrium of axial and rhombic ferric haem forms is also seen in rapidly freeze-quenched samples. Different high spin ferric haem forms were monitored during a 3 week storage of the enzyme at 4 °C. For some forms, extremal dependences, i.e. those progressing via maxima or minima over storage time, were found. This indicates that the mechanism of the time-dependent transition from one high spin ferric haem form to another must be more complex than a simple single site oxidation. PMID:22381358

Svistunenko, Dimitri A; Worrall, Jonathan A R; Chugh, Snehpriya B; Haigh, Sarah C; Ghiladi, Reza A; Nicholls, Peter

2012-02-22

217

Coupled ferric oxides and sulfates on the Martian surface.  

PubMed

The Mars Exploration Rover (MER), Opportunity, showed that layered sulfate deposits in Meridiani Planum formed during a period of rising acidic ground water. Crystalline hematite spherules formed in the deposits as a consequence of aqueous alteration and were concentrated on the surface as a lag deposit as wind eroded the softer sulfate rocks. On the basis of Mars Express Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) orbital data, we demonstrate that crystalline hematite deposits are associated with layered sulfates in other areas on Mars, implying that Meridiani-like ground water systems were indeed widespread and representative of an extensive acid sulfate aqueous system. PMID:17673623

Bibring, J-P; Arvidson, R E; Gendrin, A; Gondet, B; Langevin, Y; Le Mouelic, S; Mangold, N; Morris, R V; Mustard, J F; Poulet, F; Quantin, C; Sotin, C

2007-08-02

218

Coupled Ferric Oxides and Sulfates on the Martian Surface  

NASA Astrophysics Data System (ADS)

The Mars Exploration Rover (MER), Opportunity, showed that layered sulfate deposits in Meridiani Planum formed during a period of rising acidic ground water. Crystalline hematite spherules formed in the deposits as a consequence of aqueous alteration and were concentrated on the surface as a lag deposit as wind eroded the softer sulfate rocks. On the basis of Mars Express Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité (OMEGA) orbital data, we demonstrate that crystalline hematite deposits are associated with layered sulfates in other areas on Mars, implying that Meridiani-like ground water systems were indeed widespread and representative of an extensive acid sulfate aqueous system.

Bibring, J.-P.; Arvidson, R. E.; Gendrin, A.; Gondet, B.; Langevin, Y.; Le Mouelic, S.; Mangold, N.; Morris, R. V.; Mustard, J. F.; Poulet, F.; Quantin, C.; Sotin, C.

2007-08-01

219

Coupled Ferric Oxides and Sulfates on the Martian Surface  

Microsoft Academic Search

The Mars Exploration Rover (MER), Opportunity, showed that layered sulfate deposits in Meridiani Planum formed during a period of rising acidic ground water. Crystalline hematite spherules formed in the deposits as a consequence of aqueous alteration and were concentrated on the surface as a lag deposit as wind eroded the softer sulfate rocks. On the basis of Mars Express Observatoire

J.-P. Bibring; R. E. Arvidson; A. Gendrin; B. Gondet; Y. Langevin; S. Le Mouelic; N. Mangold; R. V. Morris; J. F. Mustard; F. Poulet; C. Quantin; C. Sotin

2007-01-01

220

The Role of the Crystallization Temperature on the Nanophase Structure Evolution of Poly[(R)-3-hydroxybutyrate].  

PubMed

The nanophase structure of semicrystalline polymers, which determines the mechanical, thermal, and gas permeability behavior, can be quantified by thermal methods. A detailed investigation of the nanophase structure of poly[(R)-3-hydroxybutyrate] (PHB) was performed under conditions of isothermal, quasi-isothermal, and nonisothermal crystallizations. The experimental analyses revealed that the establishment of the nanophase rigid amorphous fraction (RAF) in PHB depends on the temperature at which crystallization occurs. The RAF grows in parallel with the crystal phase during quasi-isothermal crystallization at 30 °C, whereas during nonisothermal crystallization at higher temperatures, RAF starts to develop at 70 °C, in correspondence with the final stages of the crystallization process. The influence of crystallization temperature on the nanophase structure was rationalized taking into account the effect of the mobility of the entangled chain segments during the phase transition. The melting behavior was found to change after isothermal crystallization at 70 °C, revealing that complete RAF mobilization is achieved approximately at this temperature. The temperature of 70 °C could be the limit for the formation and the disappearance of rigid amorphous fraction in the PHB analyzed in the present study. PMID:24020615

Righetti, Maria Cristina; Tombari, Elpidio; Di Lorenzo, Maria Laura

2013-09-25

221

NO reactions with sol-gel and solution phase samples of the ferric nitrite derivative of HbA  

PubMed Central

The reaction of nitric oxide (NO) with the ferric (met) nitrite derivative of human adult hemoglobin Hb is probed for both solution phase and sol-gel encapsulated populations. The evolution of both the Q band absorption spectrum and fitted populations of Hb derivatives are used to show the sequence of events occurring when NO interacts with nitrite bound to a ferric heme in Hb. The sol-gel is used to compare the evolving populations as a function of quaternary state for the starting met nitrite populations. The redox status of intermediates is probed using the CN? anion to trap ferric heme species. The emergent presence of reactive NO species such as N2O3 during the course of the reaction is probed using the fluorescent probe DAF-2 whereas the fluorophore Chemi-fluor is used as an indirect measure of the ability of the reaction to create S-nitrosothiols on glutathione. The results are consistent with the formation of a stable reactive intermediate capable of generating bioactive forms of NO. The patterns observed are consistent with a proposed mechanism whereby NO reacts with the ferric nitrite derivative to generate N2O3.

Roche, Camille J.; Friedman, Joel M.

2010-01-01

222

The Nox/Ferric reductase/Ferric reductase-like families of Eumycetes.  

PubMed

Reactive Oxygen Species (ROS) are involved in plant biomass degradation by fungi and development of fungal structures. While the ROS-generating NADPH oxidases from filamentous fungi are under strong scrutiny, much less is known about the related integral Membrane (or Ferric) Reductases (IMRs). Here, we present a survey of these enzymes in 29 fungal genomes covering the entire available range of fungal diversity. IMRs are present in all fungal genomes. They can be classified into at least 24 families, underscoring the high diversity of these enzymes. Some are differentially regulated during colony or fruiting body development, as well as by the nature of the carbon source of the growth medium. Importantly, functional characterization of IMRs has been made on proteins belonging to only two families, while nothing or very little is known about the proteins of the other 22 families. PMID:20943186

Grissa, Ibtissem; Bidard, Frédérique; Grognet, Pierre; Grossetete, Sandrine; Silar, Philippe

2010-07-14

223

Vegetable oil stability at elevated temperatures in the presence of ferric stearate and ferrous octanoate.  

PubMed

The thermoxidative stability of partially hydrogenated soybean oil (PHSBO) was examined after addition of ferric stearate and ferrous octanoate, and then heating the samples at 120, 160, 180, and 200 degrees C. In a second experiment, the effect of iron concentration (ferric stearate) on PHSBO stability was examined at 180 degrees C, and at concentrations of approximately 0.5 and 1.2 mg of added iron/kg PHSBO. Oil samples were heated continuously for 72 h and sampled every 12 h. The acid value, p-anisidine value, color, dielectric constant and the triacylglycerol polymer content of oil samples were compared to oil samples containing no added iron. Generally, the value of each oxidative index increased with (1) an increase in temperature, (2) an increase in heating time, and/or (3) an increase in iron. The results demonstrate that low concentrations of iron will substantially increase the rate of oxidation for vegetable oil samples heated to temperatures of 120 degrees C to 200 degrees C. PMID:15769140

Coscione, Aline R; Artz, William E

2005-03-23

224

Determination of arsenic(III) and arsenic(V) in ferric chloride-hydrochloric acid leaching media by ion chromatography  

SciTech Connect

An analytical method has been developed to determine arsenic(V) in ferric chloride-hydrochloric acid leaching media using ion chromatography with conductivity detection. Oxidation of As(III) by aqua regia allows arsenic(III) to be determined by difference. The method involves a preseparation of trace quantities of arsenic from the relatively large concentrations of ferric chloride and hydrochloric acid prior to the ion chromatography measurement. Iron(III) is separated by passing through a hydrogen-form cation exchange column, and arsenic(III) and arsenic(V) are then eluted with water. The effect of the concentration of acid in this separation is discussed. The effluent collected from the cation exchange column is evaporated to remove the hydrochloric acid. The accuracy and precision of the method were determined from the analysis of various synthetic solutions and are discussed; an accuracy of +/-4% was obtained even at arsenic(V) concentrations as low as 10 ppm. The extent of oxidation of arsenic(III) in acidic ferric chloride solution and the reduction of arsenic(V) in acidic ferrous chloride solution were measured. The results obtained by ion chromatography are compared to the values realized using colorimetry after the preseparation step. 13 references, 3 figures, 4 tables.

Tan, L.K.; Dutrizac, J.E.

1985-05-01

225

The Bacillus subtilis EfeUOB transporter is essential for high-affinity acquisition of ferrous and ferric iron.  

PubMed

Efficient uptake of iron is of critical importance for growth and viability of microbial cells. Nevertheless, several mechanisms for iron uptake are not yet clearly defined. Here we report that the widely conserved transporter EfeUOB employs an unprecedented dual-mode mechanism for acquisition of ferrous (Fe[II]) and ferric (Fe[III]) iron in the bacterium Bacillus subtilis. We show that the binding protein EfeO and the permease EfeU form a minimal complex for ferric iron uptake. The third component EfeB is a hemoprotein that oxidizes ferrous iron to ferric iron for uptake by EfeUO. Accordingly, EfeB promotes growth under microaerobic conditions where ferrous iron is more abundant. Notably, EfeB also fulfills a vital role in cell envelope stress protection by eliminating reactive oxygen species that accumulate in the presence of ferrous iron. In conclusion, the EfeUOB system contributes to the high-affinity uptake of iron that is available in two different oxidation states. PMID:23764491

Miethke, Marcus; Monteferrante, Carmine G; Marahiel, Mohamed A; van Dijl, Jan Maarten

2013-06-10

226

LIBS Studies of Ferric Salts in Frozen Solutions Under Martian Conditions  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS) is capable of investigating pure salts and frozen salt solutions. Ferric chloride can be distinguished from ferric sulfate by applying multivariate data analysis methods.

Schröder, S.; Pavlov, S.; Hübers, H.-W.; Jessberger, E. K.

2012-03-01

227

Kinetic anomalies of dissolution of sphalerite in ferric sulfate solution  

Microsoft Academic Search

During the leaching of several sphalerite concentrates in acidic ferric sulfate solution, the dissolution rate of zinc decreases with time and overall conversion does not exceed 305. The growing elemental sulfur layer on the surface of each particle was found to be the cause of this passivation. To eliminate this phenomenon, a small addition of lignosulphonate (1 g\\/l) into the

J. Lochmann; M. Ped?ik

1995-01-01

228

21 CFR 184.1296 - Ferric ammonium citrate.  

Code of Federal Regulations, 2010 CFR

...of 16.5 to 18.5 percent iron, approximately 9 percent ammonia, and 65 percent citric acid and occurs as reddish brown or garnet red scales or granules or as a brownish-yellowish powder. (2) Ferric ammonium citrate (iron (III) ammonium...

2009-04-01

229

Complexes of Ferric Ion with Salicylic Acid and Related Substances  

Microsoft Academic Search

IN connexion with this Unit's interest in the biological actions of salicylic acid and its derivatives1a and in their physical properties1b, an investigation has been made of the association of the ferric ion with some substituted salicylic acids.

M. V. Park

1963-01-01

230

Predicting anion breakthrough in granular ferric hydroxide (GFH) adsorption filters  

Microsoft Academic Search

Adsorption of arsenate, phosphate, salicylic acid, and groundwater DOC onto granular ferric hydroxide (GFH) was studied in batch and column experiments. Breakthrough curves were experimentally determined and modelled using the homogeneous surface diffusion model (HSDM) and two of its derivatives, the constant pattern homogeneous surface diffusion model (CPHSDM) and the linear driving force model (LDF). Input parameters, the Freundlich isotherm

Alexander Sperlich; Sebastian Schimmelpfennig; Benno Baumgarten; Arne Genz; Gary Amy; Eckhard Worch; Martin Jekel

2008-01-01

231

Ferric chloride-graphite intercalation compounds prepared from graphite fluoride  

Microsoft Academic Search

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

Ching-Cheh Hung

1995-01-01

232

CU(II): catalyzed hydrazine reduction of ferric nitrate  

SciTech Connect

A method is described for producing ferrous nitrate solutions by the cupric ion-catalyzed reduction of ferric nitrate with hydrazine. The reaction is complete in about 1.5 hours at 40/sup 0/C. Hydrazoic acid is also produced in substantial quantities as a reaction byproduct.

Karraker, D.G.

1981-11-01

233

Dynamics of coagulation of kaolin particles with ferric chloride  

Microsoft Academic Search

An optical monitoring technique is used to investigate the dynamics of coagulation of kaolin suspensions with ferric chloride. Particular attention is given to the effects of coagulant dose, solution pH and mixing intensity on coagulation dynamics. Results show that this monitoring method provides valuable information on the dynamics of aggregates in coagulation with Fe(III) salts.

HSIAO-WEI CHING; THEODORE S. TANAKA; MENACHEM ELIMELECHI

1994-01-01

234

Modeling of nano-sized macromolecules in silane-based self-assembled nano-phase particle coatings  

Microsoft Academic Search

Molecular simulation approaches have been used to enhance the understanding of complex chemical interactions in coatings related processes. The Self-assembled NAno-phase Particle (SNAP) coating process relies on aqueous solution processes, similar to those used in conventional sol–gel synthesis, to form siloxane nano-sized structures, which are subsequently cross-linked upon film application. This process has been shown to produce a dense, protective

V. N Balbyshev; K. L Anderson; A Sinsawat; B. L Farmer; M. S Donley

2003-01-01

235

Presence of an iron-rich nanophase material in the upper layer of the Cretaceous-Tertiary boundary clay  

Microsoft Academic Search

We report new geochemical evidence from ten Cretaceous-Tertiary boundary sites in North America and Europe, indicating the presence of a material remnant of a large asteroid or comet that struck the Earth at 65.0 Ma. Mössbauer spectroscopic data reveals that a ubiquitous iron-rich nanophase material exists at the uppermost part of the K-T boundary layer in the Western Hemisphere and

Thomas J. Wdowiak; Lawrence P. Armendarez; David G. Agresti; Manson L. Wade; Suzanne Y. Wdowiak; Philippe Claeys; Glenn Izett

2001-01-01

236

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 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....

2013-07-01

237

Evidence-based Assessment: Evaluation of the Formocresol Versus Ferric Sulfate Primary Molar Pulpotomy  

Microsoft Academic Search

Purpose: Formocresol and ferric sulfate were evaluated as pulpotomy medicaments us- ing evidence-based dentistry principles. Formocresol has been challenged as a potential carcinogen and mutagen, leading to consideration of ferric sulfate. Methods: The PICOT statement was: (P) In human carious primary molars with revers- ible coronal pulpitis, (I) does a pulpotomy performed with ferric sulfate, (C) compared with formocresol, (O)

Alex Loh; Polly O'Hoy; Xuan Tran; Rachael Charles; Andrew Hughes; Kotaro Kubo; Louise Brearley Messer

2004-01-01

238

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

PubMed

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. PMID:23989064

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

2013-09-26

239

Fabrication and modification of ordered nanoporous structures from nanophase-separated block copolymer/metal salt hybrids.  

PubMed

We report facile preparation of nanoporous thin films by rinsing out a metal salt from nanophase-separated hybrid films composed of a block copolymer and a water-soluble metal salt. Nanophase-separated hybrids were prepared by mixing polystyrene-b-poly(4-vinylpyridine) (PS-P4VP) and iron(III) chloride in a solvent of pyridine, followed by solvent-casting and thermal-annealing. Film samples with a thickness of ca. 100 nm were fabricated from the nanophase-separated hybrids by using a microtoming technique. Metal salts in the films were removed by immersion into water to fabricate nanopores. Morphological observations were conducted by using transmission electron microscopy (TEM). Ordered cylindrical nanopores were clearly observed in the thin films prepared from the water-immersed hybrids which originally present cylindrical nanodomains. These nanoporous films were modified by loading another metal salt, samarium(III) nitrate, into the nanopores on the basis of the coordination ability of P4VP tethered to the pore walls. The samples after loading treatment were evaluated by TEM observation and elemental analysis with energy dispersive X-ray spectroscopy. PMID:23214946

Sageshima, Yoshio; Arai, Shigeo; Noro, Atsushi; Matsushita, Yushu

2012-12-07

240

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

241

Bacillus cereus iron uptake protein fishes out an unstable ferric citrate trimer.  

PubMed

Citrate is a common biomolecule that chelates Fe(III). Many bacteria and plants use ferric citrate to fulfill their nutritional requirement for iron. Only the Escherichia coli ferric citrate outer-membrane transport protein FecA has been characterized; little is known about other ferric citrate-binding proteins. Here we report a unique siderophore-binding protein from the gram-positive pathogenic bacterium Bacillus cereus that binds multinuclear ferric citrate complexes. We have demonstrated that B. cereus ATCC 14579 takes up (55)Fe radiolabeled ferric citrate and that a protein, BC_3466 [renamed FctC (ferric citrate-binding protein C)], binds ferric citrate. The dissociation constant (K(d)) of FctC at pH 7.4 with ferric citrate (molar ratio 1:50) is 2.6 nM. This is the tightest binding observed of any B. cereus siderophore-binding protein. Nano electrospray ionization-mass spectrometry (nano ESI-MS) analysis of FctC and ferric citrate complexes or citrate alone show that FctC binds diferric di-citrate, and triferric tricitrate, but does not bind ferric di-citrate, ferric monocitrate, or citrate alone. Significantly, the protein selectively binds triferric tricitrate even though this species is naturally present at very low equilibrium concentrations. PMID:23027976

Fukushima, Tatsuya; Sia, Allyson K; Allred, Benjamin E; Nichiporuk, Rita; Zhou, Zhongrui; Andersen, Ulla N; Raymond, Kenneth N

2012-10-01

242

Magnetization damping in two-component metal oxide micropowder and nanopowder compacts by broadband ferromagnetic resonance measurements  

Microsoft Academic Search

The microwave damping mechanisms in magnetic inhomogeneous systems have displayed a richness of phenomenology that has attracted widespread interest over the years. Motivated by recent experiments, we report an extensive experimental study of the Gilbert damping parameter of multicomponent metal oxides micro- and nanophases. We label the former by M samples, and the latter by N samples. The main thrust

Jamal Ben Youssef; Christian Brosseau

2006-01-01

243

Using Magnetic and Optical Methods to Determine the Size and Characteristics of Nanoparticles Embedded in Oxide Semiconductors  

Microsoft Academic Search

Films of oxides doped with transition metals are frequently believed to have magnetic inclusions. Magnetic methods to determine the amount of nanophases and their magnetic characteristics are described. The amount of the sample that is paramagnetic may also be measured. Optical methods are described and shown to be very powerful to determine which defects are also magnetic.

Gillian A. Gehring; Harry J. Blythe; Qi Feng; David S. Score; Abbas Mokhtari; Marzook Alshammari; Mohammed S. Al Qahtani; A. Mark Fox

2010-01-01

244

Chronic liver iron overload in the baboon by ferric nitrilotriacetate  

Microsoft Academic Search

Two baboons receiving intramuscular injections of ferric nitrilotriacetate over a two-year period were compared with two control baboons. The results indicate that in ironoverloaded animals: (1) liver iron excess was major (maximal liver iron concentration values of 42 µmol\\/100 mg dry weight for both animals vs 1.3±0.2 (mean±sd) in controls) and chronic (for 15 months liver iron concentrations were higher

P. Brissot; J. Farjanel; D. Bourel; J. P. Campion; A. Guillouzo; A. Rattner; Y. Deugnier; B. Desvergne; B. Ferrand; M. Simon; M. Bourel

1987-01-01

245

Reaction mechanism for the ferric chloride leaching of sphalerite  

Microsoft Academic Search

Reaction mechanisms for the ferric chloride leaching of sphalerite are proposed based on data obtained in leaching and dual\\u000a cell experiments presented in this work and in a previous study. The results from the leaching experiments show that at low\\u000a concentrations the rate is proportional to [Fe3+]T\\u000a 0.5 and [Cl-]T\\u000a 0.43 but at higher concentrations the reaction order with respect

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

1985-01-01

246

Dissolution kinetics of sphalerite in acidic ferric chloride leaching  

Microsoft Academic Search

This paper presents a study for leaching kinetics of sphalerite concentrate in FeCl3–HCl solution. The shrinking core model was applied to the results of experiments investigating the effects of stirrer speed of 200–600rpm, ferric ion concentration in range of 0–1M, solid\\/liquid ratio in range of 1\\/100–1\\/5, leaching temperature range of 40–80°C and particle size on zinc dissolution rate. The activation

S. Aydogan; A. Aras; M. Canbazoglu

2005-01-01

247

Mineralogical changes occurring during the ferric lon leaching of bornite  

NASA Astrophysics Data System (ADS)

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.

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

1985-12-01

248

Mechanism of Bacterial Pyrite Oxidation  

PubMed Central

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.

Silverman, Melvin P.

1967-01-01

249

Structure and growth of quasi-one-dimensional YSi2 nanophases on Si(100)  

NASA Astrophysics Data System (ADS)

Quasi-one-dimensional YSi2 nanostructures are formed via self-assembly on the Si(100) surface. These epitaxial nanowires are metastable and their formation strongly depends on the growth parameters. Here, we explore the various stages of yttrium silicide formation over a range of metal coverages and growth temperatures, and establish a rudimentary phase diagram for these novel and often coexisting nanophases. We identify, in addition to previously identified stoichiometric wires, several new nanowire systems. These nanowires exhibit a variety of surface reconstructions, which sometimes coexist on a single wire. From a comparison of scanning tunneling microscopy images, tunneling spectra, and first-principles density functional theory calculations, we determine that these surface reconstructions arise from local orderings of yttrium vacancies. Nanowires often agglomerate into nanowire bundles, the thinnest of which are formed from single wire pairs. The calculations show that such bundles are energetically favored compared to well-separated single wires. Thicker bundles are formed at slightly higher temperature. They extend over several microns, forming a robust network of conducting wires that could possibly be employed in nanodevice applications.

Iancu, V.; Kent, P. R. C.; Hus, S.; Hu, H.; Zeng, C. G.; Weitering, H. H.

2013-01-01

250

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

PubMed

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 in glucose enrichments increased iron reduction 50-fold because the fermentation products could also be metabolized with concomitant iron reduction. Acetate, hydrogen, propionate, butyrate, ethanol, methanol, and trimethylamine stimulated the reduction of amorphous ferric oxyhydroxide in enrichments inoculated with sediments but not in uninoculated or heat-killed controls. The addition of ferric iron inhibited methane production in sediments. The degree of inhibition of methane production by various forms of ferric iron was related to the effectiveness of these ferric compounds as electron acceptors for the metabolism of acetate. The addition of acetate or hydrogen relieved the inhibition of methane production by ferric iron. The decrease of electron equivalents proceeding to methane in sediments supplemented with amorphous ferric oxyhydroxides was compensated for by a corresponding increase of electron equivalents in ferrous iron. These results indicate that iron reduction can outcompete methanogenic food chains for sediment organic matter. Thus, when amorphous ferric oxyhydroxides are available in anaerobic sediments, the transfer of electrons from organic matter to ferric iron can be a major pathway for organic matter decomposition. PMID:16347032

Lovley, D R; Phillips, E J

1986-04-01

251

Organic matter mineralization with reduction of ferric iron in anaerobic sediments  

SciTech Connect

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 in glucose enrichments increased iron reduction 50-fold because the fermentation products could also be metabolized with concomitant iron reduction. Acetate, hydrogen, propionate, butyrate, ethanol, methanol, and trimethylamine stimulated the reduction of amorphous ferric oxyhydroxide in enrichments inoculated with sediments but not in uninoculated or heat-killed controls. The addition of ferric iron inhibited methane production in sediments. The degree of inhibition of methane production by various forms of ferric iron was related to the effectiveness of these ferric compounds as electron acceptors for the metabolism of acetate. The addition of acetate or hydrogen relieved the inhibition of methane production by ferric iron. The decrease of electron equivalents proceeding to methane in sediments supplemented with amorphous ferric oxyhydroxides was compensated for by a corresponding increase of electron equivalents in ferrous iron. These results indicate that iron reduction can out compete methanogenic food chains for sediment organic matter. Thus, when amorphous ferric oxyhydroxides are available in anaerobic sediments, the transfer of electrons from organic matter to ferric iron can be a major pathway for organic matter decomposition.

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

1986-04-01

252

Organic Matter Mineralization with Reduction of Ferric Iron in Anaerobic Sediments  

PubMed Central

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 in glucose enrichments increased iron reduction 50-fold because the fermentation products could also be metabolized with concomitant iron reduction. Acetate, hydrogen, propionate, butyrate, ethanol, methanol, and trimethylamine stimulated the reduction of amorphous ferric oxyhydroxide in enrichments inoculated with sediments but not in uninoculated or heat-killed controls. The addition of ferric iron inhibited methane production in sediments. The degree of inhibition of methane production by various forms of ferric iron was related to the effectiveness of these ferric compounds as electron acceptors for the metabolism of acetate. The addition of acetate or hydrogen relieved the inhibition of methane production by ferric iron. The decrease of electron equivalents proceeding to methane in sediments supplemented with amorphous ferric oxyhydroxides was compensated for by a corresponding increase of electron equivalents in ferrous iron. These results indicate that iron reduction can outcompete methanogenic food chains for sediment organic matter. Thus, when amorphous ferric oxyhydroxides are available in anaerobic sediments, the transfer of electrons from organic matter to ferric iron can be a major pathway for organic matter decomposition.

Lovley, Derek R.; Phillips, Elizabeth J. P.

1986-01-01

253

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

NASA Astrophysics Data System (ADS)

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.

Burns, Roger G.; Fisher, Duncan S.

1991-06-01

254

Preliminary oxidation in histochemical staining methods for cholesterol.  

PubMed

The need for preliminary oxidation with histochemical methods for cholesterol was investigated on silica-coated sheets and in tissue sections. The techniques used were the Schultz reaction, perchloric acid-naphthoquinone (PAN), Lewis & Lobban's ferric alum-sulphuric acid reagent and Okamoto's iodine-sulphuric acid. The oxidants assessed were ferric chloride, ferric alum, potassium permanganate, ammonium sulphamate and ultraviolet light. The best combinations amongst those tested in order of reactivity were FeCl3-PAN, ferric alum-Schultz, Lewis-Lobban (no additional oxidant), iodine-sulphuric acid (no additional oxidant). Authentic preparations of cholesterol oxidation products were stained with these methods, but the nature of the oxidized product in the preliminary stage could not be determined. PMID:6157826

Adams, C W; High, O B

1980-08-01

255

Experimental study on a nonlinear photonics process of Er(0.5)Yb(3):FOV oxyfluoride nanophase vitroceramics  

NASA Astrophysics Data System (ADS)

We study the nonlinear photonics of rare-earth-doped oxyfluoride nanophase vitroceramics (FOV), oxyfluoride glass (FOG), and ZBLAN fluoride glass. We found that an interesting fluorescence intensity inversion phenomenon between red and green fluorescence occurs from Er(0.5)Yb(3):FOV. The dynamic range ? of the intensity inversion between red and green fluorescence of Er(0.5)Yb(3):FOV is about 5.753×102, which is 100 to 1000 times larger than those of other materials. One of the applications of this phenomenon is double-wavelength fluorescence falsification-preventing technology, which is proved to possess the novel antifriction loss and antiscribble properties.

Chen, Xiaobo; Song, Zengfu; Hu, Lili; Zhang, Junjie; Wen, Lei

2007-07-01

256

Reaction mechanism for the ferric chloride leaching of sphalerite  

NASA Astrophysics Data System (ADS)

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.

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

1985-12-01

257

U-EXTRACTION--IMPROVEMENTS IN ELIMINATION OF Mo BY USE OF FERRIC ION  

DOEpatents

An improved solvent extraction process is described whereby U may be extracted by a water immiscible organic solvent from an aqueous solution of uranyl nitrate. It has been found that Mo in the presence of phosphate ions appears to form a complex with the phosphate which extracts along with the U. This extraction of Mo may be suppressed by providing ferric ion in the solution prior to the extraction step. The ferric ion is preferably provided in the form of ferric nitrate.

Clark, H.M.; Duffey, D.

1958-06-10

258

Flocculation activity of novel ferric chloride–polyacrylamide (FeCl 3PAM) hybrid polymer  

Microsoft Academic Search

A ferric chloride–polyacrylamide inorganic–organic hybrid polymer has been synthesized using a ferric chloride\\/polyacrylamide ratio of 1:1 via free radical solution polymerization. A redox initiation system - (NH4)2S2O8 and NaHSO3 was used to initiate the polymerization at 50°C in aqueous medium. The ferric chloride–polyacrylamide hybrid polymer was characterized using Fourier transform infrared (FT-IR) spectrometer to determine their functional groups in the

Khai Ern Lee; Tjoon Tow Teng; Norhashimah Morad; Beng Teik Poh; Mohanapriya Mahalingam

2011-01-01

259

Monocyte-macrophage ferric reductase activity is inhibited by iron and stimulated by cellular differentiation.  

PubMed Central

The enzyme ferric reductase catalyses the reduction of Fe(III) as a prerequisite to its transportation across the cell membrane. Duodenal mucosal biopsies from iron overloaded patients with genetic haemochromatosis (GH) have increased ferric reductase activity and iron absorption compared with controls, yet the GH mucosa is iron deficient. A similar GH-related iron deficiency is also seen in macrophages. The aim of this study was to investigate whether macrophage ferric reductase activity is altered in GH, and to determine ferric reductase activity in monocytes and differentiated macrophages. The erythroleukaemic K562 cell line was studied as a clonal reference cell line. The basal K562 ferric reductase activity is characteristic of a membrane bound enzyme, being both temperature and protease sensitive. Ferric reductase activity was also demonstrated in human leucocyte, monocyte and macrophage preparations. Assays of K562 and macrophage cell supernatants confirmed that the ferric reductase activity was not due to a secreted factor. Assay of ferric reductase in normalized-iron and iron-enriched (100 microM ferric citrate) conditions showed no significant difference between Cys282Tyr (Cys282-->Tyr) homozygous GH macrophages and Cys282-Tyr negative control activities (P>0.05). However, a 900% increase in ferric reductase activity was observed during monocyte to macrophage differentiation (P<0.05), possibly reflecting the co-ordinate up-regulation of iron metabolism in these cells. The demonstration of approx. 25% activity after macrophage differentiation at high free-iron concentrations compared with 'normalized' iron is consistent with repression of human ferric reductase activity by iron. The identification of the human ferric reductase gene and its protein will ultimately provide insight into its regulation and role in mammalian iron metabolism.

Partridge, J; Wallace, D F; Raja, K B; Dooley, J S; Walker, A P

1998-01-01

260

Mössbauer mineralogy of rock, soil, and dust at Meridiani Planum, Mars: Opportunity's journey across sulfate-rich outcrop, basaltic sand and dust, and hematite lag deposits  

Microsoft Academic Search

The Mössbauer (MB) spectrometer on Opportunity measured the Fe oxidation state, identified Fe-bearing phases, and measured relative abundances of Fe among those phases at Meridiani Planum, Mars. Eight Fe-bearing phases were identified: jarosite (K,Na,H3O)(Fe,Al)(OH)6(SO4)2, hematite, olivine, pyroxene, magnetite, nanophase ferric oxides (npOx), an unassigned ferric phase, and metallic Fe (kamacite). Burns Formation outcrop rocks consist of hematite-rich spherules dispersed throughout

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

2006-01-01

261

Origin of Surface-Correlated and Agglutinitic Nanophase Fe0: A Bedtime Story for Bruce  

NASA Astrophysics Data System (ADS)

It has become accepted lore that the myriad of grains of nanophase Fe(sup 0) (abbrev. npFe(sup 0)) in lunar agglutinates are the result of 'auto-reduction of impact-melted lunar soil in the presence of solar-wind hydrogen'. However, recent studies have demonstrated other sources of npFe(sup 0) in lunar soils, as present in thin patinas (approx. 0.1 micron) on the surfaces of most soil particles. The major portion of this npFe(sup 0) formed by deposition of vapor produced by abundant micrometeorite impacts, as documented by the presence of multiple and overlapping patinas. A smaller portion may have formed by radiation sputtering. The vapor deposition of this patina npFe(sup 0) is not actually at the surface, sensu stricto, but just below. It would appear that the presence of npFe(sup 0) in the vapor-deposited patinas (rims) on virtually all grains of a mature soil provides an additional and abundant source for the greatly increased Is/Fe(sup 0) values observed. [At this point, I would like to see just how red with fury Bruce's face must be, as the above statements appear to steal his 'I told you so's.'.] You see, it was Bruce and his Pittsburgh colleagues that had astutely predicted all this way back in the Apollo days, but its significance went largely overlooked for decades. For an elegant and thorough review, albeit with a bit of bias, please read Hapke.

Taylor, Lawrence A.

2002-01-01

262

Comparison of ferric iron generation by different species of acidophilic bacteria immobilized in packed-bed reactors.  

PubMed

Flooded packed-bed bioreactors, prepared by immobilizing four different species of acidophilic iron-oxidizing bacteria on porous glass beads, were compared for their ferric iron-generating capacities when operated in batch and continuous flow modes over a period of up to 9 months, using a ferrous iron-rich synthetic liquor and acid mine drainage (AMD) water. The bacteria used were strains of Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, a Ferrimicrobium-like isolate (TSTR) and a novel Betaproteobacterium (isolate PSTR), which were all isolated from relatively low-temperature mine waters. Three of the bacteria used were chemoautotrophs, while the Ferrimicrobium isolate was an obligate heterotroph. Greater biomass yields achievable with the Ferrimicrobium isolate resulted in greater iron oxidation efficiency in the newly commissioned bioreactor containing this bacterium, though long-term batch testing with organic carbon-free solution resulted in similar maximum iron oxidation rates in all four bioreactors. Two of the bioreactors (those containing immobilized L. ferrooxidans and Ferrimicrobium TSTR) were able to generate significantly lower concentrations of ferrous iron than the others when operated in batch mode. In contrast, when operated as continuous flow systems, the bioreactor containing immobilized PSTR was superior to the other three when challenged with either synthetic or actual AMD at high flow rates. The least effective bacterium overall was At. ferrooxidans, which has previously been the only iron-oxidizer used in the majority of reports describing ferric iron-generating bioreactors. The results of these experiments showed that different species of iron-oxidizing acidophiles have varying capacities to oxidize ferrous iron when immobilized in packed-bed bioreactors, and that novel isolates may be superior to well-known species. PMID:17983721

Rowe, Owen F; Johnson, D Barrie

2007-11-05

263

Vivianite auto-oxidation  

Microsoft Academic Search

Vivianite, Fe3(PO4)2×8 H2O, (010) surfaces cleaved in an N2 gas atmosphere are examined using X-ray photoelectron spectroscopy (XPS). Quantitative evaluation of Fe(2p32) and O(1s) spectra show cleaved surfaces are partly oxidized. Ferric hydroxide is identified as an oxidation product. An auto-reduction-oxidation mechanism involving rupture of hydrogen bonds between the H2O ligands which hold together the sheet structure of vivianite is

Allen R. Pratt

1997-01-01

264

Vivianite auto-oxidation  

NASA Astrophysics Data System (ADS)

Vivianite, Fe3(PO4)2×8 H2O, (010) surfaces cleaved in an N2 gas atmosphere are examined using X-ray photoelectron spectroscopy (XPS). Quantitative evaluation of Fe(2p32) and O(1s) spectra show cleaved surfaces are partly oxidized. Ferric hydroxide is identified as an oxidation product. An auto-reduction-oxidation mechanism involving rupture of hydrogen bonds between the H2O ligands which hold together the sheet structure of vivianite is proposed.

Pratt, Allen R.

265

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

266

Ferredoxin-NADP+ Reductase from Pseudomonas putida Functions as a Ferric Reductase?  

PubMed Central

Pseudomonas putida harbors two ferredoxin-NADP+ reductases (Fprs) on its chromosome, and their functions remain largely unknown. Ferric reductase is structurally contained within the Fpr superfamily. Interestingly, ferric reductase is not annotated on the chromosome of P. putida. In an effort to elucidate the function of the Fpr as a ferric reductase, we used a variety of biochemical and physiological methods using the wild-type and mutant strains. In both the ferric reductase and flavin reductase assays, FprA and FprB preferentially used NADPH and NADH as electron donors, respectively. Two Fprs prefer a native ferric chelator to a synthetic ferric chelator and utilize free flavin mononucleotide (FMN) as an electron carrier. FprB has a higher kcat/Km value for reducing the ferric complex with free FMN. The growth rate of the fprB mutant was reduced more profoundly than that of the fprA mutant, the growth rate of which is also lower than the wild type in ferric iron-containing minimal media. Flavin reductase activity was diminished completely when the cell extracts of the fprB mutant plus NADH were utilized, but not the fprA mutant with NADPH. This indicates that other NADPH-dependent flavin reductases may exist. Interestingly, the structure of the NAD(P) region of FprB, but not of FprA, resembled the ferric reductase (Fre) of Escherichia coli in the homology modeling. This study demonstrates, for the first time, the functions of Fprs in P. putida as flavin and ferric reductases. Furthermore, our results indicated that FprB may perform a crucial role as a NADH-dependent ferric/flavin reductase under iron stress conditions.

Yeom, Jinki; Jeon, Che Ok; Madsen, Eugene L.; Park, Woojun

2009-01-01

267

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

PubMed

Ferric carboxymaltose (Ferinject(R)), a novel iron complex that consists of a ferric hydroxide core stabilized by a carbohydrate shell, allows for controlled delivery of iron to target tissues. Administered intravenously, it is effective in the treatment of iron-deficiency anaemia, delivering a replenishment dose of up to 1000 mg of iron during a minimum administration time of ferric carboxymaltose rapidly improves haemoglobin levels and replenishes depleted iron stores in various populations of patients with iron-deficiency anaemia, including those with inflammatory bowel disease, heavy uterine bleeding, postpartum iron-deficiency anaemia or chronic kidney disease. It was well tolerated in clinical trials. Ferric carboxymaltose is, therefore, an effective option in the treatment of iron-deficiency anaemia in patients for whom oral iron preparations are ineffective or cannot be administered. Ferric carboxymaltose is a macromolecular ferric hydroxide carbohydrate complex, which allows for controlled delivery of iron within the cells of the reticuloendothelial system and subsequent delivery to the iron-binding proteins ferritin and transferrin, with minimal risk of release of large amounts of ionic iron in the serum. Intravenous administration of ferric carboxymaltose results in transient elevations in serum iron, serum ferritin and transferrin saturation, and, ultimately, in the correction of haemoglobin levels and replenishment of depleted iron stores. The total iron concentration in the serum increased rapidly in a dose-dependent manner after intravenous administration of ferric carboxymaltose. Ferric carboxymaltose is rapidly cleared from the circulation and is distributed primarily to the bone marrow ( approximately 80%) and also to the liver and spleen. Repeated weekly administration of ferric carboxymaltose does not result in accumulation of transferrin iron in patients with iron-deficiency anaemia. Intravenously administered ferric carboxymaltose was effective in the treatment of iron-deficiency anaemia in several 6- to 12-week, randomized, open-label, controlled, multicentre trials in various patient populations, including those with inflammatory bowel disease, heavy uterine bleeding or postpartum iron-deficiency anaemia, and those with chronic kidney disease not undergoing or undergoing haemodialysis. In most trials, patients received either ferric carboxymaltose equivalent to an iron dose of ferric carboxymaltose or iron sucrose administered into the haemodialysis line two to three times weekly. In all trials, ferric carboxymaltose was administered until each patient had received his or her calculated total iron replacement dose. Haemoglobin-related outcomes improved in patients with iron-deficiency anaemia receiving ferric carboxymaltose. Treatment with ferric carboxymaltose was associated with rapid and sustained increases from baseline in haemoglobin levels. Ferric carboxymaltose was considered to be as least as effective as ferrous sulfate with regard to changes from baseline in haemoglobin levels or the proportion of patients achieving a haematopoietic response at various timepoints. In general, improvements in haemoglobin levels were more rapid with ferric carboxymaltose than with ferrous sulfate. In patients with chronic kidney disease undergoing haemodialysis, ferric carboxymaltose was at least as effective as iron sucrose. Ferric carboxymaltose also replenished depleted iron stores and improved health-related quality-of-life (HR-QOL) in patients with iron-deficiency anaemia. Recipients of ferric carboxymaltose demonstrated improvements from b

Lyseng-Williamson, Katherine A; Keating, Gillian M

2009-01-01

268

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

Microsoft Academic Search

We study apo and holo forms of the bacterial ferric binding protein (FBP) which exhibits the so-called ferric transport dilemma: it uptakes iron from the host with remarkable affinity, yet releases it with ease in the cytoplasm for subsequent use. The observations fit the ''conformational selection'' model whereby the existence of a weakly populated, higher energy conformation that is stabilized

Canan Atilgan; Ali Rana Atilgan

2009-01-01

269

Radiographic Success of Ferric Sulfate and Formocresol Pulpotomies in Relation to Early Exfoliation  

Microsoft Academic Search

Purpose: The purpose of this retrospective study was to evaluate the radiographic find- ings with formocresol and ferric sulfate pulpotomies in relation to early tooth loss. Methods: Vital pulpotomies with either ferric sulfate or formocresol, performed by fac- ulty members between 1992 and 2002 at The University of Iowa, were evaluated retrospectively. Radiographic criteria were established to assess success or

Kaaren G. Vargas; Brett Packham

2005-01-01

270

Organic matter mineralization with reduction of ferric iron in anaerobic sediments  

Microsoft Academic Search

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

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

1986-01-01

271

The effects of nanophase ceramic materials on select functions of human mesenchymal stem cells  

NASA Astrophysics Data System (ADS)

Modification of the chemistry and surface topography of nanophase ceramics can provide biomaterial formulations capable of directing the functions of adherent cells. This effect relies on the type, amount, and conformation of adsorbed proteins that mediate the adhesion of mesenchymally-descended lineages. The mechanisms driving this response are not yet well-understood and have not been investigated for human mesenchymal stem cells (HMSCs), a progenitor-lineage critical to orthopaedic biomaterials. The present study addressed these needs by examining the in vitro adhesion, proliferation, and osteogenic differentiation of HMSCs as a function of substrate chemistry and grain size, with particular attention to the protein-mediated mechanisms of cell adhesion. Alumina, titania, and hydroxyapatite substrates were prepared with 1500, 200, 50, and 24 (alumina only) nm grain sizes, and characterized with respect to surface properties, porosity, composition, and phase. Adhesion of HMSCs was dependent upon both chemistry and grain size. Specifically, adhesion on alumina and hydroxyapatite was reduced on 50 and 24 (alumina only) nm surfaces, as compared to 1500 and 200 nm surfaces, while adhesion on titania substrates was independent of grain size. Investigation into the protein-mediated mechanisms of this response identified vitronectin as the dominant adhesive protein, demonstrated random protein distribution across the substrate surface without aggregation or segregation, and confirmed the importance of the type, amount, and conformation of adsorbed proteins in cell adhesion. Minimal cell proliferation was observed on 50 and 24 (alumina only) nm substrates of any chemistry. Furthermore, cell proliferation was up-regulated on 200 nm substrates after 7 days of culture. Osteogenic differentiation was not detected on 50 nm substrates throughout the 28 day culture period. In contrast, osteogenic differentiation was strongly enhanced on 200 nm substrates, occurring approximately 7 days earlier and in greater magnitude than that observed on 1500 nm substrates. In summary, the current study elucidated the chemical and topographical cues necessary to optimize the vitronectin-mediated adhesion, proliferation, and differentiation of human mesenchymal stem cells on ceramic surfaces. These results expand the understanding of surface-mediated cell functions and provide information pertinent to the design of next-generation orthopaedic and tissue engineering biomaterials.

Dulgar-Tulloch, Aaron Joseph

272

An iron isotope perspective on the origin of the nanophase metallic iron in lunar regolith  

NASA Astrophysics Data System (ADS)

The surfaces of the Moon and other airless planetary bodies are constantly weathered by meteorite impacts and sputtering by charged particles. One of the hallmarks of this “space weathering” is the presence of nanophase metallic Fe (npFe0) at the surface of airless bodies. These npFe0 grains alter the surface optical spectra of planetary bodies without an atmosphere and their concentration is used to estimate the degree of maturity of lunar regolith. The origin of npFe0 has been debated between in situ reduction due to the solar wind, and evaporation generated by charged particle sputtering and/or micrometeorite impact followed by re-condensation of metallic Fe. These two mechanisms will impart completely different Fe isotopic fractionation effects on the npFe0. In this study we measure the Fe isotopic composition of npFe0 using a step-by-step surface etching technique on lunar regolith plagioclase. Our results show that npFe0 is highly enriched in the heavy isotopes of Fe (?56Fe up to 0.71‰) compared to bulk plagioclase and other lunar materials such as regolith and igneous rocks. We suggest that the formation of npFe0 in lunar regolith is responsible for the higher ?56Fe in the lunar regolith compared to lunar igneous rocks. In addition, a thermal escape model shows that the heavy Fe isotopic composition of npFe0 is best explained by the preferential escape of light Fe isotopes to space in the vaporization phase of Fe. The temperature of the vapor can be inferred from our model (2750-3000 K), which is compatible with those proposed by previous calculations and experiments. Therefore our results unambiguously support the vapor deposit origin of npFe0, explain the origin of the heavy Fe isotopic composition of the lunar regolith and provide a temperature estimate for the impact event at the origin of the npFe0.

Wang, Kun; Moynier, Frédéric; Podosek, Frank A.; Foriel, Julien

2012-07-01

273

Age-related accumulation of non-heme ferric and ferrous iron in mouse ovarian stroma visualized by sensitive non-heme iron histochemistry.  

PubMed

Sensitive non-heme iron histochemistry--namely, the perfusion-Perls method and perfusion-Turnbull method--was applied to study the distribution and age-related accumulation of non-heme ferric iron and ferrous iron in mouse ovary. Light and electron microscopic studies revealed that non-heme ferric iron is distributed predominantly in stromal tissue, especially in macrophages. By contrast, the distribution of non-heme ferrous iron was restricted to a few ovoid macrophages. Aged ovaries exhibited remarkable non-heme iron accumulation in all stromal cells. In particular, non-heme ferrous iron level was increased in stromal tissue, suggestive of increased levels of redox-active iron, which can promote oxidative stress. Moreover, intense localization of both non-heme ferric and ferrous iron was observed in aggregated large stromal cells that were then characterized as ceroid-laden enlarged macrophages with frothy cytoplasm. Intraperitoneal iron overload in adult mice resulted in non-heme iron deposition in the entire stroma and generation of enlarged macrophages, suggesting that excessive iron accumulation induced macrophage morphological changes. The data indicated that non-heme iron accumulation in ovarian stromal tissue may be related to aging of the ovary due to increasing oxidative stress. PMID:22108647

Asano, Yoshiya

2011-11-21

274

Age-related Accumulation of Non-heme Ferric and Ferrous Iron in Mouse Ovarian Stroma Visualized by Sensitive Non-heme Iron Histochemistry  

PubMed Central

Sensitive non-heme iron histochemistry—namely, the perfusion-Perls method and perfusion-Turnbull method—was applied to study the distribution and age-related accumulation of non-heme ferric iron and ferrous iron in mouse ovary. Light and electron microscopic studies revealed that non-heme ferric iron is distributed predominantly in stromal tissue, especially in macrophages. By contrast, the distribution of non-heme ferrous iron was restricted to a few ovoid macrophages. Aged ovaries exhibited remarkable non-heme iron accumulation in all stromal cells. In particular, non-heme ferrous iron level was increased in stromal tissue, suggestive of increased levels of redox-active iron, which can promote oxidative stress. Moreover, intense localization of both non-heme ferric and ferrous iron was observed in aggregated large stromal cells that were then characterized as ceroid-laden enlarged macrophages with frothy cytoplasm. Intraperitoneal iron overload in adult mice resulted in non-heme iron deposition in the entire stroma and generation of enlarged macrophages, suggesting that excessive iron accumulation induced macrophage morphological changes. The data indicated that non-heme iron accumulation in ovarian stromal tissue may be related to aging of the ovary due to increasing oxidative stress.

2012-01-01

275

Selective adsorption of phosphoproteins on gel-immobilized ferric chelate  

SciTech Connect

Ferric ions are very strongly adsorbed to iminodiacetic acid substituted agarose. This firmly immobilized complex acts as a selective immobilized metal affinity adsorbent for phosphoproteins. Chromatography based on this principle is illustrated by the adsorption-desorption behavior of egg yolk phosvitin before and after dephosphorylation as well as by the change in the chromatographic pattern before and after enzymic phosphorylation of selected histones. The strength of binding is dependent on the phosphate content. The difference is binding before and after phosphorylation of a single amino acid residue is demonstrated. Affinity elution can be accomplished by inclusion in the buffer of (1) phosphoserine or (2) a displacing metal ion such as Mg/sup 2 +/.

Muszynska, G.; Andersson, L.; Porath, J.

1986-11-04

276

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

PubMed Central

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.

Troxell, Bryan; Hassan, Hosni M.

2013-01-01

277

Sodium nitroprusside may modulate Escherichia coli antioxidant enzyme expression by interacting with the ferric uptake regulator.  

PubMed

Efforts to explore possible relationships between nitric oxide (NO) and antioxidant enzymes in an Escherichia coli model have uncovered a possible interaction between sodium nitroprusside (SNP), a potent, NO-donating drug, and the ferric uptake regulator (Fur), an iron(II)--dependent regulator of antioxidant and iron acquisition proteins present in Gram-negative bacteria. The enzymatic profiles of superoxide dismutase and hydroperoxidase during logarithmic phase of growth were studied via non-denaturing polyacrylamide gel electrophoresis and activity staining specific to each enzyme. Though NO is known to induce transcription of the manganese-bearing isozyme of SOD (MnSOD), treatment with SNP paradoxically suppressed MnSOD expression and greatly enhanced the activity of the iron-containing equivalent (FeSOD). Fur, one of six global regulators of MnSOD transcription, is uniquely capable of suppressing MnSOD while enhancing FeSOD expression through distinct mechanisms. We thus hypothesize that Fur is complacent in causing this behaviour and that the iron(II) component of SNP is activating Fur. E. coli was also treated with the SNP structural analogues, potassium ferricyanide (PFi) and potassium ferrocyanide (PFo). Remarkably, the ferrous PFo was capable of mimicking the SNP-related pattern, whereas the ferric PFi was not. As Fur depends upon ferrous iron for activation, we submit this observation of redox-specificity as preliminary supporting evidence for the hypothesized Fur-SNP interaction. Iron is an essential metal that the human innate immune system sequesters to prevent its use by invading pathogens. As NO is known to inhibit iron-bound Fur, and as activated Fur regulates iron uptake through feedback inhibition, we speculate that the administration of this drug may disrupt this strategic management of iron in favour of residing Gram-negative species by providing a source of iron in an otherwise iron-scarce environment capable of encouraging its own uptake. However, these gains may be counteracted by the oxidative consequences of iron and NO, as the former can catalyse the formation of toxic free radical species while the latter can inhibit enzymes and contribute to the formation of other toxic compounds. The potential consequences of SNP on microbial growth warrant future investigation. PMID:22061896

Bertrand, R; Danielson, D; Gong, V; Olynik, B; Eze, M O

2011-11-05

278

Deposition rates of oxidized iron on Mars  

NASA Astrophysics Data System (ADS)

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.

Burns, R. G.

279

Strong Oxidants are Needed to form Sulfates in CM Chondrites  

NASA Astrophysics Data System (ADS)

Oxidants (O_2, H_2O_2, O_3, etc.) produced through radiolysis and photolysis of water ice in the solar nebula could be responsible for formation of sulfates and some ferric phases in carbonaceous chondrites.

Zolotov, M. Yu.

2013-09-01

280

Spectroscopic Analysis of Soil-H_2O-CO_2 Ice Mixtures at Temperatures Ranging from 75 to 160 K and Implications for Mars  

Microsoft Academic Search

Spectroscopic measurements from 4000 to 400 cm(-1) (2.5 to 25 mu m) of Mars soil analog - ice mixtures have been performed. The analog material is a chemically-treated montmorillonite containing nanophase ferric oxide species (1). Previous spectral experiments of Mars soil analogs under reduced atmospheric pressures and temperatures showed that the spectral features due to water in these soils were

Janice L. Bishop; Robert F. Ferrante; Marla H. Moore

1996-01-01

281

Low-temperature reflectivity spectra of red hematite and the color of Mars  

Microsoft Academic Search

Reflectivity spectra (visible and near IR) were measured near 141, 210, and 300 K for four red and well-crystalline powders of hematite (red hematite) used as commercial pigments, two samples of volcanic tephra from Mauna Kea volcano that contain red hematite as their dominant pigment, three samples of palagonitic tephra from the same location that contain nanophase ferric oxide as

Richard V. Morris; D. C. Golden; James F. Bell

1997-01-01

282

Stability field and phase transition pathways of hydrous ferric sulfates in the temperature range 50 °C to 5 °C: Implication for martian ferric sulfates  

NASA Astrophysics Data System (ADS)

We report the results from a systematic laboratory investigation on the fundamental properties of hydrous ferric sulfates. The study involves 150 experiments with duration of over 4 years on the stability field and phase transition pathways under Mars relevant environmental conditions for five ferric sulfates: ferricopiapite [Fe4.67(SO4)6(OH)2·20H2O], kornelite [Fe2(SO4)3·7H2O], a crystalline and an amorphous pentahydrated ferric sulfate [Fe2(SO4)3·5H2O], and rhomboclase [FeH(SO4)2·4H2O]. During the processes of phase transitions, we observed the phenomena that reflect fundamental properties of these species and the occurrence of other common hydrous ferric sulfates, e.g. paracoquimbite [Fe2(SO4)3·9H2O]. Based on the results of this set of experiments, we have drown the boundaries of deliquescence zone of five hydrous ferric sulfates and estimated the regions of their stability field in temperature (T) - relative humidity (RH) space. Furthermore, we selected the experimental parameters for a next step investigation, which is to determine the location of the phase boundary between two solid ferric sulfates, kornelite [Fe2(SO4)3·7H2O] and pentahydrated ferric sulfate [Fe2(SO4)3·5H2O]. The experimental observations in ferricopiapite dehydration processes were used to interpret the observed spectral change of Fe-sulfate-rich subsurface soils on Mars after their exposure by the Spirit rover to current martian atmospheric conditions.

Wang, Alian; Ling, Zongcheng; Freeman, John J.; Kong, Weigang

2012-03-01

283

The phase diagram of the system bismuth oxide-ferric oxide  

Microsoft Academic Search

1.The system Bi2O3-Fe2O3 was studied by the method of differential thermal analysis and we have given the phase diagram of the system.2.The curve of the liquidus system consists of six crystallization branches: Fe2O3, Bi2Fe4O9, a- and ß-BiFeO3, a compound of the assumed composition 20Bi2O3·Fe2O3, and Bi2O3.3.BiFeO3 has a reversible transformation at 825°; this ferrite melts incongruently at 930°.4.Bi2Fe4O9 also melts

E. I. Speranskaya; V. M. Skorikov; E. Ya. Rode; V. A. Terekhova

1965-01-01

284

Experimental study on a nonlinear photonics process of Er(0.5)Yb(3):FOV oxyfluoride nanophase vitroceramics.  

PubMed

We study the nonlinear photonics of rare-earth-doped oxyfluoride nanophase vitroceramics (FOV), oxyfluoride glass (FOG), and ZBLAN fluoride glass. We found that an interesting fluorescence intensity inversion phenomenon between red and green fluorescence occurs from Er(0.5)Yb(3):FOV. The dynamic range summation operator of the intensity inversion between red and green fluorescence of Er(0.5)Yb(3):FOV is about 5.753 x 10(2), which is 100 to 1000 times larger than those of other materials. One of the applications of this phenomenon is double-wavelength fluorescence falsification-preventing technology, which is proved to possess the novel antifriction loss and antiscribble properties. PMID:17632629

Chen, Xiaobo; Song, Zengfu; Hu, Lili; Zhang, Junjie; Wen, Lei

2007-07-15

285

Synthesis and XRD/PL Studies of Pure and Sb2O3 Doped ZnO Nanophases  

SciTech Connect

Pure and Sb2O3 (0 to 5% molar fraction) doped ZnO nanophases were synthesized using a sublimation-condensation method in a solar furnace. The initial and final powders were characterized by X-ray diffraction (XRD) and photoluminescence (PL) techniques. XRD results showed no significant change in the lattice parameters and the presence of a new phase Zn7O2Sb12 in the highly doped micropowders but not in the nanopowders. The photoluminescence spectra showed a strong donor-acceptor pair (DAP) emission in the pure untreated ZnO micropowder which is drastically reduced in pure and doped nanopowders. The donor-bound excitonic band (DX) includes three well resolved peaks in the PL spectra of the doped micropowders while the spectra of doped nanopowders showed a broader band. Furthermore, the free exciton emission was absent in all doped samples.

Boulares, N.; Guergouri, K. [Mentouri University, Constantine (Algeria); Tabet, N. [King Fahd University of Petroleum and Minerals (Saudi Arabia); Monty, C. [CNRS/Promes, Odeillo 66120 Font-Romeu (France)

2007-08-22

286

Structural insights into the coordination of iron by Thermus thermophilus HB8 ferric binding protein A.  

PubMed

The ferric binding protein belongs to the substrate-binding protein super-family and transports ferric ions across the periplasmic space in gram negative bacteria. This process involves the binding and release of ferric ions through conformational changes of the ferric binding protein, and the assistance of a synergistic anion. Here we report the crystal structure of Thermus thermophilus HB8's (TtFbpA) ferric binding protein A in four different forms, which represent the apo state (apo-TtFbpA), the carbonate-bound state (TtFbpACO3),and the iron- and carbonate-bound state (TtFbpAFeCO3). The ferric ion in TtFbpAFeCO3 is bound by three tyrosine residues from TtFbpA and one synergistic carbonate ion. Structural comparisons among the three different states reveal the molecular mechanisms of iron-binding by TtFbpA. Our results, together with previous studies on other bacterial periplasmic ferric binding proteins, provide a complete understanding of the structural basis for iron binding and release in the periplasm of gram-negative bacteria. PMID:23545257

Wang, Qing; Lu, Qingyu; Zhou, Qiyun; Wang, Xinquan; Liu, Xiaoqing

2013-03-29

287

Binding of Ferric Enterobactin by the Escherichia coli Periplasmic Protein FepB  

PubMed Central

The periplasmic protein FepB of Escherichia coli is a component of the ferric enterobactin transport system. We overexpressed and purified the binding protein 23-fold from periplasmic extracts by ammonium sulfate precipitation and chromatographic methods, with a yield of 20%, to a final specific activity of 15,500 pmol of ferric enterobactin bound/mg. Periplasmic fluid from cells overexpressing the binding protein adsorbed catecholate ferric siderophores with high affinity: in a gel filtration chromatography assay the Kd of the ferric enterobactin-FepB binding reaction was approximately 135 nM. Intrinsic fluorescence measurements of binding by the purified protein, which were more accurate, showed higher affinity for both ferric enterobactin (Kd = 30 nM) and ferric enantioenterobactin (Kd = 15 nM), the left-handed stereoisomer of the natural E. coli siderophore. Purified FepB also adsorbed the apo-siderophore, enterobactin, with comparable affinity (Kd = 60 nM) but did not bind ferric agrobactin. Polyclonal rabbit antisera and mouse monoclonal antibodies raised against nearly homogeneous preparations of FepB specifically recognized it in solid-phase immunoassays. These sera enabled the measurement of the FepB concentration in vivo when expressed from the chromosome (4,000 copies/cell) or from multicopy plasmids (>100,000 copies/cell). Overexpression of the binding protein did not enhance the overall affinity or rate of ferric enterobactin transport, supporting the conclusion that the rate-limiting step of ferric siderophore uptake through the cell envelope is passage through the outer membrane.

Sprencel, Cathy; Cao, Zhenghua; Qi, Zengbiao; Scott, Daniel C.; Montague, Marjorie A.; Ivanoff, Nora; Xu, Jide; Raymond, Kenneth M.; Newton, Salete M. C.; Klebba, Phillip E.

2000-01-01

288

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...

289

Thermally altered palagonitic tephra - A spectral and process analog to the soil and dust of Mars  

NASA Astrophysics Data System (ADS)

Six palagonitic soil samples (PH-1 through PH-6) which were collected at 30-cm intervals from a lava slab on Mauna Kea, Hawaii, are studied. The samples present an alteration sequence caused by heating during emplacement of molten lava over a preexisting tephra cone. Techniques employed include visible and near-IUR spectroscopy, Moessbauer spectroscopy, and magnetic analysis. The four samples closest to the slab (PH-1 through PH-4) were strongly altered in response to heating during its emplacement; their iron oxide mineralogy is dominated by nanophase ferric oxide. The sample adjacent to the slab (PH-1) has a factor of 3 less H2O and contains crystalline hematite and magnetite in addition to nanophase ferric oxide. It is argued that localized thermal alteration events may provide a volumetrically important mechanism for the palagonitization of basaltic glass and the production of crystalline ferric oxides on Mars.

Bell, J. F.; Morris, R. V.; Adams, J. B.

1993-02-01

290

Characterization of the quinone reductase activity of the ferric reductase B protein from Paracoccus denitrificans.  

PubMed

The ferric reductase B (FerB) protein of Paracoccus denitrificans exhibits activity of an NAD(P)H: Fe(III) chelate, chromate and quinone oxidoreductase. Sequence analysis places FerB in a family of soluble flavin-containing quinone reductases. The enzyme reduces a range of quinone substrates, including derivatives of 1,4-benzoquinone and 1,2- and 1,4-naphthoquinone, via a ping-pong kinetic mechanism. Dicoumarol and Cibacron Blue 3GA are competitive inhibitors of NADH oxidation. In the case of benzoquinones, FerB apparently acts through a two-electron transfer process, whereas in the case of naphthoquinones, one-electron reduction takes place resulting in the formation of semiquinone radicals. A ferB mutant strain exhibited an increased resistance to 1,4-naphthoquinone, attributable to the absence of the FerB-mediated redox cycling. The ferB promoter displayed a high basal activity throughout the growth of P. denitrificans, which could not be further enhanced by addition of different types of naphthoquinones. This indicates that the ferB gene is expressed constitutively. PMID:19138657

Sedlácek, Vojtech; van Spanning, Rob J M; Kucera, Igor

2008-12-30

291

Lipid peroxidation in plasma of rats treated with ferric-nitrilotriacetate, in relation to kidney and liver modifications.  

PubMed

Intraperitoneal injection of the iron chelate ferric-nitrilotriacetate (Fe-NTA) induces in rodents renal and hepatic suffering, associated with oxidative damage. We investigated the oxidation pattern in plasma of treated rats in relation to liver and kidney, monitoring the variation of the lipid components more susceptible to oxidation, unsaturated fatty acids (UFA) and alpha-tocopherol, as biomarkers of the oxidative damage. A sublethal dose of Fe-NTA induced a strong and extremely significant decrease of UFA levels at 1 h after injection in the plasma compartment and at 3 h in the kidney, with reductions up to 40-50% of the control values, together with an increase of conjugated dienes fatty acids hydroperoxides and a consumption of alpha-tocopherol. The same modifications were observed in the liver, but to a lesser extent. Histological observation proved that biochemical changes in the lipid fraction were a direct consequence of an ongoing membrane lipid peroxidation process. Our data show that oxidative damage to the lipid fraction is initially evident in the plasma compartment, where Fe-NTA toxicity is assumed to be caused by the elevation of serum free iron concentration, and proceeds with different speed and severity in the kidney and liver. PMID:15817997

Deiana, Monica; Rosa, Antonella; Corona, Giulia; Collu, Stefania; Ennas, Maria Grazia; Dessì, Maria Assunta

2005-01-01

292

Ferric Leghemoglobin in Plant-Attached Leguminous Nodules.  

PubMed

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 (Melilotus officinalis) and soybean (Glycine max [L.] Merr.) roots exposed to various conditions. The effects of N2 and O2 streams and elevated nicotinate levels on root-attached nodules were tested to determine whether the spectrophotometric technique was showing the predicted responses of Lb. The soybean and sweet clover nodules' Lb spectra indicated predominantly ferrous Lb and LbO2 in young (34 d) plants. As the nodule aged beyond 45 d, it was possible to induce Lb3+ with a 100% O2 stream (15 min). At 65 d without inducement, the nodule Lb status indicated the presence of some Lb3+ along with ferrous Lb and oxyferrous Lb. Nicotinate and fluoride were used as ligands to identify Lb3+. Computer-calculated difference spectra were used to demonstrate the changes in Lb spectra under different conditions. Some conditions that increased absorbance in the 626 nm region (indicating Lb3+ accumulation) were root-fed ascorbate and dehydroascorbate, plant exposure to darkness, and nodule water immersion. PMID:12228593

Lee, Kk.; Shearman, L. L.; Erickson, B. K.; Klucas, R. V.

1995-09-01

293

Ferric Leghemoglobin in Plant-Attached Leguminous Nodules.  

PubMed Central

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 (Melilotus officinalis) and soybean (Glycine max [L.] Merr.) roots exposed to various conditions. The effects of N2 and O2 streams and elevated nicotinate levels on root-attached nodules were tested to determine whether the spectrophotometric technique was showing the predicted responses of Lb. The soybean and sweet clover nodules' Lb spectra indicated predominantly ferrous Lb and LbO2 in young (34 d) plants. As the nodule aged beyond 45 d, it was possible to induce Lb3+ with a 100% O2 stream (15 min). At 65 d without inducement, the nodule Lb status indicated the presence of some Lb3+ along with ferrous Lb and oxyferrous Lb. Nicotinate and fluoride were used as ligands to identify Lb3+. Computer-calculated difference spectra were used to demonstrate the changes in Lb spectra under different conditions. Some conditions that increased absorbance in the 626 nm region (indicating Lb3+ accumulation) were root-fed ascorbate and dehydroascorbate, plant exposure to darkness, and nodule water immersion.

Lee, Kk.; Shearman, L. L.; Erickson, B. K.; Klucas, R. V.

1995-01-01

294

Ferric Iron Nanoparticle Formation Mediated By Negatively Charged Polypeptides  

NASA Astrophysics Data System (ADS)

The creation of magnetite particles by magnetotactic bacteria has been of great interest for a number of years. Previous studies have shown that magnetite nanocrystals have been synthesized in the presence of recombinant Mms6 protein. Mms6 plays a vital role in the biomineralization of bacterial magnetite nanocrystals. The objective of this research is to determine the effect of functional group type on size and shape of magnetic nanoparticles formed by biomineralization. Control over the size of nanoparticles is paramount. Use of nanoparticles as contrast agents in MRI is advantageous, as they are small enough to be localized in desired region by applying local magnetic fields. Sequences VA-Mms6, VA1, VA2, and VA3 were designed with modifications in the functional groups Mms6 sequence. Solutions of peptide were mixed with ferric and ferro salts and allowed to interact under inert atmosphere. The nanoparticles formed are examined under SEM and TEM and compared for differences. The SEM and TEM images of nanoparticles produced with the aid of the above peptides had similarity to those produced in the magnetotactic bacteria. However, discrete particles with a narrower size range were produced using the peptide VA2. XPS, AFM, DLS and MFM were also done on the synthesized nanoparticles. The results were in good agreement when compared to those with a standard control sample of magnetite nanoparticles. Use of peptides with different functional groups may provide a unique route to produce uniform magnetite nanocrystals with definite control of morphology.

Aluru, Vamsi Krishna

295

Localized corrosion of candidate container materials in ferric chloride solutions  

SciTech Connect

Localized corrosion behavior of candidate inner and outer container materials of currently-designed nuclear waste package was evaluated in aqueous solutions of various concentrations of ferric chloride (FeCl{sub 3}) at 30 C, 60 C and 90 C using the electrochemical cyclic potentiodynamic polarization (CPP) technique. Materials tested include A 5 16 carbon steel and high-performance alloys 825, G-3, G-30, C-4, 625. C-22, and Ti Gr-12. A 516 steel suffered from severe general and localized attack including pitting and crevice corrosion. High-nickel alloys 825 and G-3 also became susceptible to severe pitting and crevice corrosion. The extent of localized attack was less pronounced in alloys G-30 and C-4. Alloy 625 experienced severe surface degradation including general corrosion, crevice corrosion and intergranular attack. In contrast, only a slight crevice corrosion tendency was observed with nickel-base alloy C-22 in solutions containing higher concentrations of FeCl{sub 3} at 60 C and 90 C. Ti Gr-12 was immune to localized attack in all tested environments. The test solutions showed significant amount of precipitated particles during and after testing especially at higher temperatures.

Fleming, D L; Lum, B Y; Roy, A K

1998-10-01

296

Iron fortification of flour with a complex ferric orthophosphate  

SciTech Connect

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.

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

1989-07-01

297

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

PubMed Central

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.

Santiago, Palacios

2012-01-01

298

Influence of pH on Dosage Requirements of Ferric Chloride.  

National Technical Information Service (NTIS)

This study investigates the feasibility of reducing the dosage requirement of ferric chloride for the removal of colloidal particles from waters containing low alkalinity by manipulating the pH control of the coagulation process. When metallic salts such ...

E. P. Galarraga

1980-01-01

299

Reaction kinetics of the ferric chloride leaching of sphalerite—an experimental study  

Microsoft Academic Search

Chloride leaching processes have significant potential for treating complex sulfides. One advantage of chloride leaching is\\u000a fast dissolution rates for most sulfide minerals. This experimental study is concerned with ferric chloride leaching of sphalerite,\\u000a a common component of many complex concentrates. The effects of stirring, temperature, ferric ion concentration, and particle\\u000a size have been examined. In addition, reaction residues at

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

1984-01-01

300

Ferric ion mediated photochemical decomposition of perfluorooctanoic acid (PFOA) by 254 nm UV light  

Microsoft Academic Search

The great enhancement of ferric ion on the photochemical decomposition of environmentally persistent perfluorooctanoic acid (PFOA) under 254nm UV light was reported. In the presence of 10?M ferric ion, 47.3% of initial PFOA (48?M) was decomposed and the defluorination ratio reached 15.4% within 4h reaction time. While the degradation and defluorination ratio greatly increased to 80.2% and 47.8%, respectively, when

Yuan Wang; Pengyi Zhang; Gang Pan; Hao Chen

2008-01-01

301

X-ray Diffraction Study of Ferric Calcium Silicate Perovskite to 62 GPa  

Microsoft Academic Search

The effect of ferric iron in calcium silicate perovskite (Ca-pv) has not been studied, although significant solubility was documented (Wang and Yagi,1998). We have synthesized ferric Ca-pv from natural Ca3Fe2Si3O12 (andradite) starting material in the laser-heated diamond cell and measured X-ray diffraction patterns at 19-62 GPa. Samples were loaded with pressure medium (either Ar or NaCl) and heated to 2000

S. Lundin; S. Shim; G. Shen; V. Prankapenka; H. Liu; Y. Meng

2005-01-01

302

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

Microsoft Academic Search

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

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

2000-01-01

303

Photooxidation of bisphenol A (BPA) in water in the presence of ferric and carboxylate salts  

Microsoft Academic Search

In this work, the photooxidation of bisphenol A (BPA), a suspected endocrine disruptor (ED), in water in the presence of ferric and oxalate ions was investigated in a concentric reactor under a 125W high-pressure mercury lamp (??365nm). The photooxidation efficiencies were dependent on the pH values and ferric\\/oxalate concentration ratios (Fe(III)\\/Ox) in the water, with higher efficiency at pH 3.50±0.05

Danna Zhou; Feng Wu; Nansheng Deng; Wu Xiang

2004-01-01

304

Effects of cupric and ferric ions on in vitro lipid peroxidation of human serum  

SciTech Connect

Transition metal ions especially ferric ions can catalytically generate free radicals by the Haber-Weiss reaction and initiate lipid peroxidation. Such processes may contribute to the mechanism of acute toxicity by transition metals. Serum pools were prepared from normal blood donors and incubated with 1mM cupric or ferric ions at 37C for 24h. Lipid peroxidation products were subsequently measured by 2-thiobarbituric acid assay as described by Yagi and the values were expressed as {mu}mol/L malonaldehyde equivalents. In another experiment, lipoproteins were coprecipitated with other proteins by 10% phosphotungstic acid/sulfuric acid and precipitates in aqueous suspension were incubated with 1 mM cupric or ferric ions. When sera were incubated, the authors observed higher concentrations of lipid peroxidation products with cupric ions compared to samples supplemented with ferric ions. The mean value for peroxidation products in control group was 2.5 {mu}mol/L. However, the effect was reversed when protein precipitates were incubated in presence of such ions. Ferric ions also caused more peroxidation of linoleic acid and phosphatidylcholine isolated from egg yolk when compared to cupric ions. Such differential behavior may be attributed to different degree of chelation of ferric and cupric ions with serum proteins.

Dasgupta, A.; Peng, Y.; Zdunek, T. (Univ. of Chicago, IL (United States))

1991-03-15

305

Ferric-Pyoverdine Recognition by Fpv Outer Membrane Proteins of Pseudomonas protegens Pf-5  

PubMed Central

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.

Hartney, Sierra L.; Mazurier, Sylvie; Girard, Maeva K.; Mehnaz, Samina; Davis, Edward W.; Gross, Harald; Lemanceau, Philippe

2013-01-01

306

Formation, aggregation and reactivity of amorphous ferric oxyhydroxides on dissociation of Fe(III)-organic complexes in dilute aqueous suspensions  

NASA Astrophysics Data System (ADS)

While chemical reactions that take place at the surface of amorphous ferric oxides (AFO) are known to be important in aquatic systems, incorporation of these reactions into kinetic models is hindered by a lack of ability to reliably quantify the reactivity of the surface and the changes in reactivity that occur over time. Long term decreases in the reactivity of iron oxides may be considered to result from changes in the molecular structure of the solid, however, over shorter time scales where substantial aggregation may occur, the mechanisms of reactivity loss are less clear. Precipitation of AFO may be described as a combination of homogeneous and heterogeneous reactions, however, despite its potentially significant role, the latter reaction is usually neglected in kinetic models of aquatic processes. Here, we investigate the role of AFO in scavenging dissolved inorganic ferric (Fe(III)) species (Fe') via the heterogeneous precipitation reaction during the net dissociation of organically complexed Fe(III) in seawater. Using sulfosalicylic acid (SSA) as a model ligand, AFO was shown to play a significant role in inducing the net dissociation of the Fe-SSA complexes with equations describing both the heterogeneous precipitation reaction and the aging of AFO being required to adequately describe the experimental data. An aggregation based mechanism provided a good description of AFO aging over the short time scale of the experiments. The behaviour of AFO described here has implications for the bioavailability of iron in natural systems as a result of reactions involving AFO which are recognised to occur over time scales of minutes, including adsorption of Fe' and AFO dissolution, precipitation and ageing.

Bligh, Mark W.; Waite, T. David

2010-10-01

307

Electrodissolution of electrodeposited iron oxides  

SciTech Connect

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.

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

308

Cost-Minimization Analysis Favours Intravenous Ferric Carboxymaltose over Ferric Sucrose for the Ambulatory Treatment of Severe Iron Deficiency  

PubMed Central

Objective Intravenous iron is widely used to treat iron deficiency in day-care units. Ferric carboxymaltose (FCM) allows administration of larger iron doses than iron sucrose (IS) in each infusion (1000 mg vs. 200 mg). As FCM reduces the number of infusions required but is more expensive, we performed a cost-minimization analysis to compare the cost impact of the two drugs. Materials and Methods The number of infusions and the iron dose of 111 consecutive patients who received intravenous iron at a gastrointestinal diseases day-care unit from 8/2007 to 7/2008 were retrospectively obtained. Costs of intravenous iron drugs were obtained from the Spanish regulatory agencies. The accounting department of the Hospital determined hospital direct and indirect costs for outpatient iron infusion. Non-hospital direct costs were calculated on the basis of patient interviews. In the pharmacoeconomic model, base case mean costs per patient were calculated for administering 1000 mg of iron per infusion using FCM or 200 mg using IS. Sensitivity analysis and Monte Carlo simulation were performed. Results Under baseline assumptions, the estimated cost of iron infusion per patient and year was €304 for IS and €274 for FCM, a difference of €30 in favour of FCM. Adding non-hospital direct costs to the model increased the difference to €67 (€354 for IS vs. €287 for FCM). A Monte Carlo simulation taking into account non-hospital direct costs favoured the use of FCM in 97% of simulations. Conclusion In this pharmacoeconomic analysis, FCM infusion reduced the costs of iron infusion at a gastrointestinal day-care unit.

Calvet, Xavier; Ruiz, Miquel Angel; Dosal, Angelina; Moreno, Laura; Lopez, Maria; Figuerola, Ariadna; Suarez, David; Miquel, Mireia; Villoria, Albert; Gene, Emili

2012-01-01

309

Oxidation of diethylene glycol with ozone and modified Fenton processes  

Microsoft Academic Search

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

Tuba Turan-Ertas; Mirat D. Gurol

2002-01-01

310

Bacterially-mediated precipitation of ferric iron during the leaching of basaltic rocks  

NASA Astrophysics Data System (ADS)

The bacterially-mediated oxidation of ferrous [Fe(II)] iron in environments where its oxidation is otherwise unfavorable (i.e., acidic and/or anaerobic conditions) results in the formation of ferric iron [Fe(III)] precipitates. The mineralogy and morphologies of these precipitates are dictated by solution biochemistry. In this study, we evaluated Fe(III) precipitates that formed during aerobic bioleaching experiments with Acidithiobacillus ferrooxidans and ilmenite (FeTiO3) and Lunar or Martian basaltic stimulant rocks. Growth media was supplied to support the bacteria; however, all the Fe(II) for chemical energy was supplied by the mineral or rock. During the experiments, the bacteria actively oxidized Fe(II) to Fe(III), resulting in the formation of white and yellow-colored precipitates. In our initial experiments with both ilmentite and basalt, High-Resolution Scanning Electron Microscopic (HRSEM) analysis indicated that the precipitates where small (diameters were less than 5?m and mostly nanometer-scaled), white, and exhibited a platy texture. Networks of mineralized bacterial biofilm were also abundant. In these cases the white precipitates coated the bacteria, forming rod-shaped minerals 5-10?m long by about 1?m in diameter. Many of the rod-shaped minerals formed elongated chains. Energy Dispersive Spectra (EDS) analysis showed that the precipitates were largely composed of Fe and phosphorous (P) with an atomic Fe:P ratio of ˜1. Limited sulfur (S) was also identified as part of the agglomerated precipitates with an atomic Fe:S ratio that ranged from 5 to 10. Phosphorous and S were introduced into the system in considerable amounts as part of the growth media. Additional experiments were performed where we altered the growth media to lower the amount of available P by an order of magnitude. In this case, the experimental behavior remained the same, but the precipitates were more yellow or orange in color relative to those in the experiments using the original growth media. HRSEM/EDS analysis confirmed the presence of minerals with much higher Fe:P ratios (˜2) and much smaller Fe:S ratios (˜0.15). This suggests that the change in growth media chemistry was reflected in precipitates that were rich in S and poorer in P. X-ray diffraction analysis of these precipitates is currently underway. Our results have implications for the interpretation of solution chemistries and precipitation mechanisms associated with biologically-mediated Fe(III)-minerals on Earth, but might also provide insights into possible biosignatures in extraterrestrial systems.

Schnittker, K.; Navarrete, J. U.; Cappelle, I. J.; Borrok, D. M.

2011-12-01

311

Role of ascorbic acid in counteracting ferric nitrilotriacetate-induced nephrotoxicity in rats.  

PubMed

Abstract Context: Ascorbic acid (AA) is a naturally occurring organic compound with antioxidant properties. It is necessary for normal growth and development, and has been shown to protect against tissue toxicity and oxidative stress. Objective: The protective effect of AA against nephrotoxicity induced in albino rats by ferric nitrilotriacetate (Fe-NTA) was evaluated. Materials and methods: Male albino rats of Wistar strain (4-6 weeks old) weighing 125-150?g were used in this study. Animals were given a single dose of Fe-NTA (9?mg/kg body weight, intraperitoneal) after a week of treatment with AA (1 and 2?mg/animal/day). Results: Fe-NTA treatment enhanced microsomal lipid peroxidation (LPO) and hydrogen peroxide (H2O2) generation to 1.7- to 2.2-fold, glutathione (GSH) levels were decreased by two-fold and the activities of GSH metabolizing enzymes decreased to a range of 2.2- to 2.5-fold in renal tissue. These changes were reversed significantly in animals receiving pretreatment of AA. Treatment of rats with AA prior to the treatment with Fe-NTA decreased microsomal LPO and H2O2 generation to 124 and 172%, and also resulted in the recovery of reduced levels of GSH, GSH-metabolizing enzymes to almost 92% at the higher dose level of AA. Discussion and conclusion: AA protects against Fe-NTA-induced nephrotoxicity and renal damage. AA has a beneficial impact on Fe-NTA-induced toxicity due to its scavenging and antioxidant effect in albino rats. PMID:24024952

Ansar, S; Iqbal, M

2013-09-12

312

Sorption of lanthanum(III), cobalt(II) and iodide ions at trace concentrations on ferric hydroxide  

Microsoft Academic Search

Summary The sorption of lanthanum(III), cobalt(II) and iodide traces was studied in dependence on the solid-liquid contact time, pH value and the properties of the carrier (internally or externally formed). The ferric hydroxide carrier was prepared by mixing aqueous ferric chloride and ammonia solutions. The results are discussed in regard to colloidal properties of the ferric hydroxide and mechanisms of

J. Šipalo-Žuljevi?; R. H. H. Wolf

1973-01-01

313

Crystal Structures of a Novel Ferric Reductase from the Hyperthermophilic Archaeon Archaeoglobus fulgidus and Its Complex with NADP +  

Microsoft Academic Search

Background: Studies performed within the last decade have indicated that microbial reduction of Fe(III) to Fe(II) is a biologically significant process. The ferric reductase (FeR) from Archaeoglobus fulgidus is the first reported archaeal ferric reductase and it catalyzes the flavin-mediated reduction of ferric iron complexes using NAD(P)H as the electron donor. Based on its catalytic activity, the A. fulgidus FeR

Hsiu-Ju Chiu; Eric Johnson; Imke Schröder; Douglas C. Rees

2001-01-01

314

Corrosion resistance of electrodeposited RE-Ni-W-P-SiC-PTFE composite coating in phosphoric and ferric chloride  

Microsoft Academic Search

Corrosion rate and anode polarization curves of electrodeposited RE-Ni-W-P-SiC-PTFE composite coating in various concentrations of phosphoric and ferric chloride were researched. The results show that corrosion rate of the composite coatings increases with the increasing concentrations of phosphoric and ferric chloride, and reaches the maximum value when phosphoric concentration is 40% and ferric chloride concentration is 20% (mass fraction, the

Rui-dong XU; Zhong-cheng GUO; Jun-yi PAN

2006-01-01

315

Vibrational Dynamics of Ferric MbCN-A Revisit by Resonance Raman and Vibrational Coherence Spectroscopy  

NASA Astrophysics Data System (ADS)

Ultrafast pump-probe spectroscopy has indicated that there exists a photoproduct state following the excitation of ferric MbCN^[1][2]. This excited state decays with a time constant of 3.6 ps^[1]. Previous studies on this system have suggested that in this photoproduct state, the heme is either (i) still six-coordinated but vibrationally hot in the electronic ground state^[1] or (ii) the proximal histidine residue (His93) is transiently dissociated, while CN^- is still bound^[2]. Recent resonance Raman measurements on ferric MbCN in static solution yield spectra that are very similar to ferric myoglobin, which has His93 and a water molecule as axial ligands. This indicates that a water molecule replaces CN^- in ferric MbCN under continuous laser excitation. Photolysis of CN^- from the heme iron is necessary to make this happen, which is not consistent with the above two suggestions. In this presentation we will revisit the dynamics of ferric MbCN with resonance Raman and vibrational coherence spectroscopy and try to explain how a water molecule competes with CN^- in binding to the heme under photo excitation^[3]. References: [1]Helbing J. et al., Biophys J, vol 87, 1881(2004) [2]Gruia F. et al., Biophys J, vol 94, 2252(2008) [3]Cao W. et al., Biochemistry, vol 40, 5728(2001)

Zeng, Weiqiao; Sun, Yuhan; Benabbas, Abdelkrim; Champion, Paul M.

2012-02-01

316

Electrical transport and magnetoresistive properties of nanophasic La1-XAXMnO3 (A = Ca, Sr and Na) manganites  

NASA Astrophysics Data System (ADS)

With a view to understand the electrical transport and magnetoresistance behavior of divalent (Ca & Sr) and monovalent (Na) substituted nanophasic lanthanum manganites, a series of materials were prepared using co-precipitation route by sintering at 800 °C. The effect of doping has been investigated in terms of structural, grain size, metal-insulator transition and variation in magnetoresistance properties for La0.7Ca0.3MnO3 (LCMO), La0.7Sr0.3MnO3 (LSMO) and La0.8Na0.2MnO3 (LNMO) samples. The X-ray diffraction data were analyzed using Rietveld refinement technique. It has been found that the samples doped with Sr and Na having rhombohedral structure with R-3c space group. The sample with Ca doping crystallizes into orthorhombic structure with Pnma space group. From resistivity measurements, it is found that all the samples exhibit metal-insulator transition (TMI) in the range of 201-261 K, which is low as compared to the samples prepared by ceramic route. The electrical resistivity data were analyzed using various theoretical models.

Mankadia, S. R.; Bhalodia, J. A.

2013-06-01

317

Vivianite auto-oxidation  

Microsoft Academic Search

Vivianite, Fe3(PO4)2×8?H2O, (010) surfaces cleaved in an N2 gas atmosphere are examined using X-ray photoelectron spectroscopy (XPS). Quantitative evaluation of Fe(2p\\u000a 32) and O(1s) spectra show cleaved surfaces are partly oxidized. Ferric hydroxide is identified as an oxidation product. An auto-reduction-oxidation\\u000a mechanism involving rupture of hydrogen bonds between the H2O ligands which hold together the sheet structure of vivianite is

Allen R. Pratt

1997-01-01

318

Microbial acquisition of iron from ferric iron bearing minerals  

SciTech Connect

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Iron is a universal requirement for all life forms. Although the fourth most abundant element in the geosphere, iron is virtually insoluble at physiological pH in oxidizing environments, existing mainly as very insoluble oxides and hydroxides. Currently it is not understood how iron is solubilized and made available for biological use. This research project addressed this topic by conducting a series of experiments that utilized techniques from both soil microbiology and mineral surface geochemistry. Microbiological analysis consisted of the examination of metabolic and physiological responses to mineral iron supplements. At the same time mineral surfaces were examined for structural changes brought about by microbially mediated dissolution. The results of these experiments demonstrated that (1) bacterial siderophores were able to promote the dissolution of iron oxides, (2) that strict aerobic microorganisms may use anaerobic processes to promote iron oxide dissolution, and (3) that it is possible to image the surface of iron oxides undergoing microbial dissolution.

Hersman, L.E. [Los Alamos National Lab., NM (United States); Sposito, G. [Univ. of California, Berkeley, CA (United States)

1998-12-31

319

Juvenile ferric iron prevents microbiota dysbiosis and colitis in adult rodents  

PubMed Central

AIM: To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice. METHODS: Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe2+) iron salt or ferric (Fe3+) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated using quantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria. RESULTS: Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg protein vs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po - 6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po - 6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood. CONCLUSION: Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.

Ettreiki, Chourouk; Gadonna-Widehem, Pascale; Mangin, Irene; Coeffier, Moise; Delayre-Orthez, Carine; Anton, Pauline M

2012-01-01

320

The formation of ferric haem during low-temperature photolysis of horseradish peroxidase Compound I.  

PubMed Central

Illumination at low temperature of the peroxide compound of horseradish peroxidase (HRP-I) causes partial conversion of the haem electronic structure from a ferryl-porphyrin radical species into a low-spin ferric state. Magnetic-c.d. (m.c.d.) and e.p.r. spectral features of the photolysis product are almost identical with those of the alkaline form of ferric HRP, proposed on the basis of its near-i.r. m.c.d. spectrum to be a Fe(III)-OH species. The ferric product of HRP-I photolysis also contains free-radical e.p.r. signals. Conversion of HRP-I into the Fe(III)-OH species, which requires transfer of a proton and two electrons from the protein, is shown to be a two-step process.

Foote, N; Gadsby, P M; Berry, M J; Greenwood, C; Thomson, A J

1987-01-01

321

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

PubMed

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

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

322

A systematic spectroscopic study of eight hydrous ferric sulfates relevant to Mars  

NASA Astrophysics Data System (ADS)

Ferric sulfates were observed on Mars during orbital remote sensing and surface explorations. These observations have stimulated our systematic experimental investigation on the formative conditions, stability fields, phase boundaries, and phase transition pathways of these important minerals. We report here the results from the first step of this project: eight synthesized anhydrous and hydrous crystalline ferric sulfates and their structural characters reflected through spectroscopic studies. A few phenomena observed during the 150 sets of on-going experiments for stability field study are also reported, which reveal the structural distortions that can happen under environmental conditions relevant to Mars.

Ling, Z. C.; Wang, Alian

2010-10-01

323

New family of ferric spin clusters incorporating redox-active ortho-dioxolene ligands.  

PubMed

Seven new di-, tri-, tetra-, and hexanuclear iron complexes that incorporate a polydentate Schiff base and variously substituted catecholate ligands have been synthesized from the trinuclear precursor [Fe(3)(OAc)(3)(L)(3)] (1), where LH(2) = 2-[[(2-hydroxyethyl)imino]phenylmethyl]-phenol. These were isolated as the compounds [Fe(3)(OAc)(Cat)(L)(3)] (2), [Fe(6)(OAc)(2)(Cat)(4)(L)(4)] (3), [Fe(4)(3,5-DBCat)(2)(L)(4)] (4), [Bu(4)N][Fe(4)(OAc)(3,5-DBCat)(4)(L)(2)] (5a, 5(-) is the complex monoanion [Fe(4)(OAc)(3,5-DBCat)(4)(L)(2)](-)), [Fe(4)(OAc)(3,5-DBCat)(3)(3,5-DBSQ)(L)(2)] (6), [Fe(2)(Cl(4)Cat)(2)(L)(LH(2))(H(2)O)] (7), and [Et(3)NH](2)[Fe(2)(Cl(4)Cat)(2)(L)(2)] (8a, 8(2-) is the complex dianion [Fe(2)(Cl(4)Cat)(2)(L)(2)](2-)), where CatH(2) = catechol; 3,5-DBCatH(2) = 3,5-di-tert-butyl-catechol; 3,5-DBSQH = 3,5-di-tert-butyl-semiquinone, and Cl(4)CatH(2) = tetrachlorocatechol. While compounds 2-4, 5a, 7, and 8a were obtained by directly treating 1 with the appropriate catechol, compound 6 was synthesized by chemical oxidation of 5a. These compounds have been characterized by single crystal X-ray diffraction, infrared and UV-visible spectroscopy, voltammetry, UV-visible spectroelectrochemistry, and magnetic susceptibility and magnetization measurements. An electrochemical study of the three tetranuclear complexes (4, 5(-), and 6) reveals multiple reversible redox processes due to the o-dioxolene ligands, in addition to reductive processes corresponding to the reduction of the iron(III) centers to iron(II). A voltammetric study of the progress of the chemical oxidation of compound 5a, together with a spectroelectrochemical study of the analogous electrochemical oxidation, indicates that there are two isomeric forms of the one-electron oxidized product. A relatively short-lived neutral species (5) that possesses the same ligand arrangement as complex 5(-) is the kinetic product of both chemical and electrochemical oxidation. After several hours, this species undergoes a significant structural rearrangement to convert to complex 6, which appears to be largely driven by the preference for the 3,5-DBSQ(-) ligand to bind in a non-bridging mode. Variable temperature magnetic susceptibility measurements for compounds 3, 4, 5a, 6, 7, and 8a reveal behavior dominated by pairwise antiferromagnetic exchange interactions, giving rise to a poorly isolated S = 0 ground state spin for compound 3, well-isolated S = 0 ground state spins for complexes 4, 5(-), 7 and 8(2-), and a well-isolated S = 1/2 ground state spin for complex 6. The ground state spin values were confirmed by low temperature variable field magnetization measurements. The thermal variation of the magnetic susceptibility for compounds 3, 4, 5a, 6, 7, and 8a were fitted and/or simulated using the appropriate Hamiltonians to derive J values that are consistent with magnetostructural correlations that have been reported previously for alkoxo-bridged ferric complexes. PMID:19594116

Mulyana, Yanyan; Nafady, Ayman; Mukherjee, Arindam; Bircher, Roland; Moubaraki, Boujemaa; Murray, Keith S; Bond, Alan M; Abrahams, Brendan F; Boskovic, Colette

2009-08-17

324

Suboxic Deposition of Ferric Iron by Bacteria in Opposing Gradients of Fe(II) and Oxygen at Circumneutral pH  

PubMed Central

The influence of lithotrophic Fe(II)-oxidizing bacteria on patterns of ferric oxide deposition in opposing gradients of Fe(II) and O2 was examined at submillimeter resolution by use of an O2 microelectrode and diffusion microprobes for iron. In cultures inoculated with lithotrophic Fe(II)-oxidizing bacteria, the majority of Fe(III) deposition occurred below the depth of O2 penetration. In contrast, Fe(III) deposition in abiotic control cultures occurred entirely within the aerobic zone. The diffusion microprobes revealed the formation of soluble or colloidal Fe(III) compounds during biological Fe(II) oxidation. The presence of mobile Fe(III) in diffusion probes from live cultures was verified by washing the probes in anoxic water, which removed ca. 70% of the Fe(III) content of probes from live cultures but did not alter the Fe(III) content of probes from abiotic controls. Measurements of the amount of Fe(III) oxide deposited in the medium versus the probes indicated that ca. 90% of the Fe(III) deposited in live cultures was formed biologically. Our findings show that bacterial Fe(II) oxidation is likely to generate reactive Fe(III) compounds that can be immediately available for use as electron acceptors for anaerobic respiration and that biological Fe(II) oxidation may thereby promote rapid microscale Fe redox cycling at aerobic-anaerobic interfaces.

Sobolev, Dmitri; Roden, Eric E.

2001-01-01

325

Nanophase hydroxyapatite and poly(lactide-co-glycolide) composites promote human mesenchymal stem cell adhesion and osteogenic differentiation in vitro.  

PubMed

Human mesenchymal stem cells (hMSCs) typically range in size from 10 to 50 ?m and proteins that mediate hMSC adhesion and differentiation usually have a size of a few nanometers. Nanomaterials with a feature size smaller than 100 nm have demonstrated the unique capability of promoting osteoblast (bone forming cell) adhesion and long-term functions, leading to more effective bone tissue regeneration. For new bone deposition, MSCs have to be recruited to the injury or disease sites and then differentiate into osteoblasts. Therefore, designing novel nanomaterials that are capable of attracting MSCs and directing their differentiation is of great interest to many clinical applications. This in vitro study investigated the effects of nanophase hydroxyapatite (nano-HA), nano-HA/poly(lactide-co-glycolide) (PLGA) composites and a bone morphogenetic protein (BMP-7) derived short peptide on osteogenic differentiation of hMSCs. The short peptide was loaded by physical adsorption to nano-HA or by dispersion in nanocomposites and in PLGA to determine their effects on hMSC adhesion and differentiation. The results showed that the nano-HA/PLGA composites promoted hMSC adhesion as compared to the PLGA controls. Moreover, nano-HA/PLGA composites promoted osteogenic differentiation of hMSCs to a similar extent with or without the presence of osteogenic factors in the media. In the MSC growth media without the osteogenic factors, the nanocomposites supported greater calcium-containing bone mineral deposition by hMSC than the BMP-derived short peptide alone. The nanocomposites provided promising alternatives in controlling the adhesion and differentiation of hMSCs without osteogenic factors from the culture media, and, thus, should be further studied for clinical translation and the development of novel nanocomposite-guided stem cell therapies. PMID:22772475

Lock, Jaclyn; Nguyen, Thanh Yen; Liu, Huinan

2012-07-07

326

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 ...

327

ELECTRODE MEASUREMENT OF REDOX POTENTIAL IN ANAEROBIC FERRIC/FERROUS CHLORIDE SYSTEMS  

EPA Science Inventory

The behaviour of two inert redox electrodes (Pt and wax-impregnated graphite) was investigated in anaerobic ferrous and ferric chloride solutions in order to establish if these electrodes respond to the Fe3+/Fe2+ couple in a Nernstian manner. A new method fo...

328

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

Microsoft Academic Search

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

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

2006-01-01

329

Spin-state crossover of ferric iron in magnesium silicate perovskite under pressure  

NASA Astrophysics Data System (ADS)

Iron-bearing magnesium silicate perovskite, the most abundant mineral in the Earth, contains both ferrous and ferric iron. In contrast to ferrous iron, most likely occupying the 8-12 coordinate site (A site), ferric iron also occupies the octahedral site (B site). The spin-state crossover of the ferric iron, which may affect the structural and elastic properties of the host phase, is therefore more complicated than that in ferrous iron and is still unclear. Most of the previous calculations have suggested a crossover from the high-spin (HS) to the low-spin (LS) state occurring at the A site in the lower-mantle pressure, while experiments suggest a HS-LS crossover at the B site being more likely. We will report a series of density functional theory + Hubbard U (DFT+U) calculations investigating possible mechanisms for the spin-state crossover in ferric-iron-bearing perovskite. This work was primarily supported by the MRSEC Program of NSF under Award Number DMR-0212302 and DMR-0819885, and partially supported by NSF under ATM-0428774 (V-Lab), EAR-1019853, and EAR-0810272. The computations were performed at the Minnesota Supercomputing Institute (MSI).

Hsu, H.; Cococcioni, M.; Wentzcovitch, R. M.

2010-12-01

330

Evaluation of the antioxidant activity of flavonoids by “ferric reducing antioxidant power” assay and cyclic voltammetry  

Microsoft Academic Search

Flavonoids, naturally occurring phenolic compounds, have recently been studied extensively for their antioxidant properties. The structure–antioxidant activity relationships (SAR) of flavonoids have been evaluated against different free radicals, but “ferric reducing antioxidant power” (FRAP) assay, which determines directly the reducing capacity of a compound, has not been used for this purpose. In this study, the antioxidant activities of 18 structurally

Omidreza Firuzi; Antonio Lacanna; Rita Petrucci; Giancarlo Marrosu; Luciano Saso

2005-01-01

331

Measurement and analysis of rate data: The rate of reaction of ferric iron with pyrite  

Microsoft Academic Search

Geochemists use several types of experiments to measure the rates of geochemical processes and analyze the results of these experiments by a variety of methods. In order to assess the efficacy of these experiments and methods of analysis, we measured the rate of reaction of ferric iron with pyrite using batch, mixed flow, and plug flow reactors and analyzed the

J. Donald Rimstidt; William D. Newcomb

1993-01-01

332

Positive control of ferric siderophore receptor gene expression by the Irr protein in Bradyrhizobium japonicum.  

PubMed

Ferric siderophore receptors are components of high-affinity iron-chelate transport systems in gram-negative bacteria. The genes encoding these receptors are generally regulated by repression. Here, we show that the ferrichrome receptor gene bll4920 and four additional putative ferric siderophore receptor genes in Bradyrhizobium japonicum are positively controlled by the regulatory protein Irr, as observed by the low level of mRNA transcripts in an irr mutant in iron-limited cells. Potential Irr binding sites with iron control element (ICE)-like motifs were found upstream and distal to the transcription start sites of the five receptor genes. However, purified recombinant Irr bound only some of those elements. Nevertheless, dissection of the bll4920 promoter region showed that a component in extracts of wild-type cells grown in iron-limited media bound only in the ICE motif region of the promoter. This binding was not observed with extracts of cells from the parent strain grown under high-iron conditions or from an irr mutant strain. Furthermore, gel mobility supershift experiments identified Irr as the binding protein in cell extracts. Chromatin immunoprecipitation experiments demonstrated that Irr occupies the promoters of the five ferric iron transport genes in vivo. We conclude that Irr is a direct positive regulator of ferric iron transport in B. japonicum. PMID:19114488

Small, Sandra K; Puri, Sumant; Sangwan, Indu; O'Brian, Mark R

2008-12-29

333

The secreted pyomelanin pigment of Legionella pneumophila confers ferric reductase activity.  

PubMed

The virulence of Legionella pneumophila is dependent upon its capacity to acquire iron. To identify genes involved in expression of its siderophore, we screened a mutagenized population of L. pneumophila for strains that were no longer able to rescue the growth of a ferrous transport mutant. However, an unusual mutant was obtained that displayed a strong inhibitory effect on the feoB mutant. Due to an insertion in hmgA that encodes homogentisate 1,2-dioxygenase, the mutant secreted increased levels of pyomelanin, the L. pneumophila pigment that is derived from secreted homogentisic acid (HGA). Thus, we hypothesized that L. pneumophila-secreted HGA-melanin has intrinsic ferric reductase activity, converting Fe(3+) to Fe(2+), but that hyperpigmentation results in excessive reduction of iron that can, in the case of the feoB mutant, be inhibitory to growth. In support of this hypothesis, we demonstrated, for the first time, that wild-type L. pneumophila secretes ferric reductase activity. Moreover, whereas the hyperpigmented mutant had increased secreted activity, an lly mutant specifically impaired for pigment production lacked the activity. Compatible with the nature of HGA-melanins, the secreted ferric reductase activity was positively influenced by the amount of tyrosine in the growth medium, resistant to protease, acid precipitable, and heterogeneous in size. Together, these data represent the first demonstration of pyomelanin-mediated ferric reduction by a pathogenic bacterium. PMID:17548481

Chatfield, Christa H; Cianciotto, Nicholas P

2007-06-04

334

Determination of aluminum, lead, and vanadium in North Atlantic seawater after coprecipitation with ferric hydroxide  

Microsoft Academic Search

Recent advances in instrumentation technology for atomic absorption spectrometry using the heated graphite furnace now make it possible to analyze for many trace metals after concentration from small volumes (50-200 mL) of seawater when the major ions are eliminated. Coprecipitation with ferric hydroxide requires few reagents and minimal sample manipulation, suggesting its use as a routine preconcentration procedure for the

Clifford P. Weisel; Robert A. Duce; James L. Fasching

1984-01-01

335

Letters to the editor/Location of catalytic iron in reduced graphite ferric chloride  

SciTech Connect

Published experimental work by Parkash, Chakrabartty, and Hooley provides evidence that hydrogen and carbon monoxide do not diffuse into intercalated graphite/ferric chloride, so that any difference between physical mixtures of iron and graphite and the intercalated catalyst in the Fischer-Tropsch synthesis must be due to surface iron (Vertical BarCarbon 1.

Parkash, S. (Alberta Res. Counc.); Hooley, J.G.; Kikuchi, E.; Ino, T.; Morita, Y.

1980-03-01

336

Breakthrough behavior of granular ferric hydroxide (GFH) fixed-bed adsorption filters: modeling and experimental approaches  

Microsoft Academic Search

Breakthrough curves (BTC) for the adsorption of arsenate and salicylic acid onto granulated ferric hydroxide (GFH) in fixed-bed adsorbers were experimentally determined and modeled using the homogeneous surface diffusion model (HSDM). The input parameters for the HSDM, the Freundlich isotherm constants and mass transfer coefficients for film and surface diffusion, were experimentally determined. The BTC for salicylic acid revealed a

Alexander Sperlich; Arne Werner; Arne Genz; Gary Amy; Eckhard Worch; Martin Jekel

2005-01-01

337

The late diagenetic conversion of pyrite to magnetite by organically complexed ferric iron  

Microsoft Academic Search

The geochemistry of late stage diagenetic replacement of pyrite by magnetite was investigated by laboratory experiments of pyrite dissolution and magnetite precipitation involving organically complexed ferric iron. The design of the experiments is based on the hypothesized geochemical conditions for in situ diagenesis in the Pennsylvanian age Belden Formation, an organic-rich carbonate in northwestern Colorado with pyrite grains rimmed with

L. A. Brothers; M. H. Engel; R. D. Elmore

1996-01-01

338

Resistance to rice blast induced by ferric chloride, di-potassium hydrogen phosphate and salicylic acid  

Microsoft Academic Search

Ferric chloride, di-potassium hydrogen phosphate and salicylic acid were tested for their capacity to suppress rice blast under greenhouse and field conditions. In greenhouse experiments, the chemicals significantly reduced disease severity when applied as a soil drench, thus demonstrating a systemic effect. Foliar spray, but not seed treatment, also caused a reduction in blast severity. In field experiments conducted at

H. K. Manandhar; H. J. Lyngs Jørgensen; S. B. Mathur; V. Smedegaard-Petersen

1998-01-01

339

DETERMINATION OF TOTAL ANTIOXIDANT CAPACITY OF GREEN TEAS BY THE FERRIC REDUCING\\/ANTIOXIDANT POWER ASSAY  

Microsoft Academic Search

Green tea is one of the important sources of bioactive compounds which have been used in folk medicine for many centuries. This study aimed to compare in vitro antioxidant power of different types of green tea (Camellia sinensis). Antioxidant activity of methanolic (50%) extracts of five green tea samples was investigated according to Ferric reducing ability power method. Total phenolic

M. Hajimahmoodi; M. Hanifeh; M. R. Oveisi; N. Sadeghi; B. Jannat

340

Processing of a ferric anolyte produced by a copper electrowinning cell based on reactive electro dialysis  

Microsoft Academic Search

The processing of a Fe-containing anolyte produced by a copper electro winning process carried out in a reactive electro dialysis (RED) cell has been studied. The resulting anolyte was an acidic aqueous solution which contained FeIII species. This solution can be used: (a) as a leaching agent or (b) as a source of commercially valuable ferric sulfate. Two operations were

J. M. Casas; P. Acuña-Goycolea; G. Crisóstomo; L. Cifuentes

2008-01-01

341

The Helicobacter pylori Homologue of the Ferric Uptake Regulator Is Involved in Acid Resistance  

Microsoft Academic Search

The only known niche of the human pathogen Helicobacter pylori is the gastric mucosa, where large fluctu- ations of pH occur, indicating that the bacterial response and resistance to acid are important for successful colonization. One of the few regulatory proteins in the H. pylori genome is a homologue of the ferric uptake regulator (Fur). In most bacteria, the main

Jetta J. E. Bijlsma; Barbara Waidner; Arnoud H. M. van Vliet; Nicky J. Hughes; Stefan Bereswill; David J. Kelly; Manfred Kist; Johannes G. Kusters

2002-01-01

342

Critical conditions for ferric chloride-induced flocculation of freshwater algae.  

PubMed

The effects of algae concentration, ferric chloride dose, and pH on the flocculation efficiency of the freshwater algae Chlorella zofingiensis can be understood by considering the nature of the electrostatic charges on the algae and precipitate surfaces. Two critical conditions are identified which, when met, result in flocculation efficiencies in excess of 90% for freshwater algae. First, a minimum concentration of ferric chloride is required to overcome the electrostatic stabilization of the algae and promote bridging of algae cells by hydroxide precipitates. At low algae concentrations, the minimum amount of ferric chloride required increases linearly with algae concentration, characteristic of flocculation primarily through electrostatic bridging by hydroxide precipitates. At higher algae concentrations, the minimum required concentration of ferric chloride for flocculation is independent of algae concentration, suggesting a change in the primary flocculation mechanism from bridging to sweep flocculation. Second, the algae must have a negative surface charge. Experiments and surface complexation modeling show that the surface charge of C. zofingiensis is negative above a pH of 4.0 ± 0.3 which agrees well with the minimum pH required for effective flocculation. These critical flocculation criteria can be extended to other freshwater algae to design effective flocculation systems. PMID:21882173

Wyatt, Nicholas B; Gloe, Lindsey M; Brady, Patrick V; Hewson, John C; Grillet, Anne M; Hankins, Matthew G; Pohl, Phillip I

2011-09-09

343

THE QUANTUM YIELD OF OXYGEN PRODUCTION BY CHLOROPLASTS SUSPENDED IN SOLUTIONS CONTAINING FERRIC OXALATE  

PubMed Central

1. The quantum yield of oxygen liberation by spinach and Tradescantia chloroplasts suspended in solutions containing ferric oxalate and potassium ferricyanide varied from 0.013 to 0.080. 2. It was concluded that the nature of this oxygen liberation reaction is not fundamentally different from the formation of oxygen in normal photosynthesis, with respect to its light efficiency.

French, C. S.; Rabideau, G. S.

1945-01-01

344

Enterobactin protonation and iron release: structural characterization of the salicylate coordination shift in ferric enterobactin.  

PubMed

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 [Fe(III)(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 [Fe(III)(H(3)Ent)](0) has been the source of some controversy and confusion in the literature. To demonstrate the proposed change of coordination from the tris-catecholate [Fe(III)(Ent)](3)(-) to the tris-salicylate [Fe(III)(H(3)Ent)](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 beta(110)() values of 39 and 38 respectively) similar to those of [Fe(III)(H(3)Ent)](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 [Fe(III)(H(3)Ent)](0) complex (d(Fe)(-)(O) = 1.98 A, sigma(2)(stat)(O) = 0.00351(10) A(2)) exhibits a shorter average Fe-O bond length but a much higher static Debye-Waller factor for the first oxygen shell than the catecholate [Fe(III)(Ent)](3)(-) complex (d(Fe)(-)(O) = 2.00 A, sigma(2)(stat)(O) = 0.00067(14) A(2)). (1)H NMR spectroscopy was used to monitor the amide bond rotation between the catecholate and salicylate geometries using the gallic complexes of enterobactin: [Ga(III)(Ent)](3)(-) and [Ga(III)(H(3)Ent)](0). The ferric salicylate complexes display quasi-reversible reduction potentials from -89 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

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

2006-07-12

345

Phase characterization and grain size effects of nanophase Y2O3, ZrO2 and Y2O3-ZrO2 composites produced by the gas-phase condensation technique.  

National Technical Information Service (NTIS)

Nanophase (n-) ZrO(sub 2) was produced in its pure and partially stabilized form by the gas-phase condensation method. The material was examined by x-ray diffraction and Raman scattering to obtain information on the structural evolution of the material du...

C. M. Foster G. R. Bai J. C. Parker M. N. Ali

1992-01-01

346

Induction of the Root Cell Plasma Membrane Ferric Reductase (An Exclusive Role for Fe and Cu).  

PubMed Central

Induction of ferric reductase activity in dicots and nongrass monocots is a well-recognized response to Fe deficiency. Recent evidence has shown that Cu deficiency also induces plasma membrane Fe reduction. In this study we investigated whether other nutrient deficiencies could also induce ferric reductase activity in roots of pea (Pisum sativum L. cv Sparkle) seedlings. Of the nutrient deficiencies tested (K, Mg, Ca, Mn, Zn, Fe, and Cu), only Cu and Fe deficiencies elicited a response. Cu deficiency induced an activity intermediate between Fe-deficient and control plant activities. To ascertain whether the same reductase is induced by Fe and Cu deficiency, concentration- and pH-dependent kinetics of root ferric reduction were compared in plants grown under control, -Fe, and -Cu conditions. Additionally, rhizosphere acidification, another process induced by Fe deficiency, was quantified in pea seedlings grown under the three regimes. Control, Fe-deficient, and Cu-deficient plants exhibited no major differences in pH optima or Km for the kinetics of ferric reduction. However, the Vmax for ferric reduction was dramatically influenced by plant nutrient status, increasing 16- to 38-fold under Fe deficiency and 1.5- to 4-fold under Cu deficiency, compared with that of control plants. These results are consistent with a model in which varying amounts of the same enzyme are deployed on the plasma membrane in response to plant Fe or Cu status. Rhizosphere acidification rates in the Cu-deficient plants were similarly intermediate between those of the control and Fe-deficient plants. These results suggest that Cu deficiency induces the same responses induced by Fe deficiency in peas.

Cohen, C. K.; Norvell, W. A.; Kochian, L. V.

1997-01-01

347

The Oxidation of Iron in a Gel Using Consumer Chemicals  

NASA Astrophysics Data System (ADS)

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.

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

2005-11-01

348

The Oxidation of Iron in a Gel Using Consumer Chemicals  

Microsoft Academic Search

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.

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

2005-01-01

349

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

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

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

350

New Evidence for the Origin of Layered Deposits in Valles Marineris  

Microsoft Academic Search

Results from CRISM, HiRISE, and CTX on MRO provide new insights into the origin of interior layered deposits (ILDs) in Valles Marineris. A well-exposed, thick sequence in western Candor Chasma has spectral properties consistent with basaltic sand mixed with nanophase iron oxide-rich dust, with the addition of sulfates and crystalline ferric oxides. Most of the deposit is dominated spectrally by

S. Murchie; F. Seelos; L. Roach; J. Mustard; R. Milliken; R. Arvidson; S. Wiseman; K. Lichtenberg; J. Andrews-Hanna; J. Bibring; J. Bishop; M. Parente; R. Morris

2008-01-01

351

ATR-FTIR spectroscopic studies of boric acid adsorption on hydrous ferric oxide  

Microsoft Academic Search

Boron is an important micronutrient for plants, but high B levels in soils are often responsible for toxicity effects in plants. It is therefore important to understand reactions that may affect B availability in soils. In this study, Attenuated Total Reflectance Fourier transform Infrared (ATR-FTIR) spectroscopy was employed to investigate mechanisms of boric acid (B(OH)3) and borate (B(OH)4?) adsorption on

Derek Peak; George W Luther III; DONALD L. SPARKS

2003-01-01

352

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

Microsoft Academic Search

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

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

1970-01-01

353

Regulation of Fe-oxide Formation Among Fe-oxidizing Bacteria  

Microsoft Academic Search

Helical stalks (resembling Gallionella ferruginea, Mariprofundus ferrooxydans) and filamentous sheaths (resembling Leptothrix ochracea) of Fe-oxidizing bacteria (FeOB) are mineralized by hydrous ferric oxides (HFO). To perform both inter-species and inter-site size comparisons of HFO particles on stalks and sheaths we measured HFO particles in samples of natural bacteriogenic iron oxides (BIOS) from 3 contrasting field sites: the Loihi Seamount (southern

Rachel E. James; Steven D. Scott; Danielle Fortin; Ian D. Clark; F. Grant Ferris

2012-01-01

354

The role of rare-earth dopants in nanophase zirconia catalysts for automotive emission control.  

SciTech Connect

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.

Loong, C.-K.; Ozawa, M.

1999-07-16

355

Epitaxial growth of nanophase magnetite in Martian meteorite Allan Hills 84001: implications for biogenic mineralization.  

PubMed

Crystallographic relationships between magnetite, sulfides, and carbonate rosettes in fracture zones of the Allan Hills (ALH) 84001 Martian meteorite have been studied using analytical electron microscopy. We have focused on those magnetite grains whose growth mechanisms can be rigorously established from their crystallographic properties. Individual magnetite nanocrystals on the surfaces of carbonates are epitaxially intergrown with one another in "stacks" of single-domain crystals. Other magnetite nanocrystals are epitaxially intergrown with the surfaces of the carbonate substrates. The observed magnetite/carbonate (hkl) Miller indices orientation relationships are (1, 1,3)m ¿¿ (1, 1 ,0)c and (1, 1 ,1)m ¿¿ (0,0, 3)c with lattice mismatches of approximately 13% and approximately 11%, respectively. Epitaxy is a common mode of vapor-phase growth of refractory oxides like magnetite, as is the spiral growth about axial screw dislocations previously observed in other magnetite nanocrystals in ALH 84001. Epitaxy rules out intracellular precipitation of these magnetites by (Martian) organisms, provides further evidence of the high-temperature (> 120 degrees C) inorganic origins of magnetite in ALH 84001, and indicates that the carbonates also have been exposed to elevated temperatures. PMID:11543075

Bradley, J P; McSween, H Y; Harvey, R P

1998-07-01

356

X-ray Diffraction Study of Ferric Calcium Silicate Perovskite to 62 GPa  

NASA Astrophysics Data System (ADS)

The effect of ferric iron in calcium silicate perovskite (Ca-pv) has not been studied, although significant solubility was documented (Wang and Yagi,1998). We have synthesized ferric Ca-pv from natural Ca3Fe2Si3O12 (andradite) starting material in the laser-heated diamond cell and measured X-ray diffraction patterns at 19-62 GPa. Samples were loaded with pressure medium (either Ar or NaCl) and heated to 2000 K before each measurement. Au and Pt were used as internal pressure standards during separate runs. Major diffraction lines observed after laser heating are consistent with those of perovskite structure. We found a mixture of ferric Ca-pv and andradite exists after laser-heating at 21 GPa. Cold compression of andradite to 40 GPa followed by laser-heating resulted in complete transformation to ferric Ca-pv. EBS imagery and EPMA analysis show no evidence of phase separation to hematite and Ca-pv. Thus our results indicate the solubility of ferric iron in Ca-pv is at least 25 mol%, which is accommodated by substitution into both the Ca- and Si- sites. Near 30 GPa a new peak appears, which can not be explained by rigid octahedral tilting in perovskite nor Fe2O3. Splitting of the 200 line becomes distinct at 40 GPa, which is identical to the tetragonal distortion reported for pure Ca-pv. We found that the volume of ferric Ca-pv is identical to pure Ca-pv reported by Mao et al (1989) and Shim et al (2002) within the uncertainty at 42-58 GPa, when the Pt scale is used. We also found that the pressure calculated from the Pt scale (Holmes et al., 1989) is systematically higher than that from the gold scale (Shim et al., 2002 and Heinz et al., 1989). Based on the fact that the 300 K EOS for Au was determined using a combination of static compression and shock-wave data, we believe that Au is a better pressure standard to use than Pt. Because the EOS for Ca-pv is based on the Pt scale, our results suggest the bulk modulus of Ca-pv may be 9-24% lower than previously suggested.

Lundin, S.; Shim, S.; Shen, G.; Prankapenka, V.; Liu, H.; Meng, Y.

2005-12-01

357

A change in antioxidative capacity as a measure of onset to oxidation in pasteurized milk  

Microsoft Academic Search

The shelf-life of dairy products is the result of a delicate balance between the activity of anti- and pro-oxidants. During storage, an imbalance between the presence of reactive oxidants and the antioxidant defence mechanism can cause oxidation. The objective of this study was to investigate the added value of methods that measure the antioxidative capacity, such as the ‘Ferric Reducing

K. Smeta; K. Raes; J. De Block; L. Herman; K. Dewettinck; K. Coudijzer

2008-01-01

358

Retention of strontium, cesium, lead and uranium by bacterial iron oxides from a subterranean environment  

Microsoft Academic Search

Bacteriogenic Fe oxides (BIOS) and groundwater samples were collected 195 m underground at the Stråssa Mine in central Sweden. Ferrous iron oxidizing bacteria, including stalked Gallionellaferruginea and filamenous Leptothrix sp., were prominent in the BIOS samples. The BIOS samples were found to contain only poorly ordered (amorphous) hydrous ferric oxide, as determined by X-ray diffraction. Inductively coupled plasma mass spectroscopy

F. G Ferris; R. O Hallberg; B Lyvén; K Pedersen

2000-01-01

359

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)

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.

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

2007-12-01

360

Using Crystal Structure Groups to Understand Mössbauer parameters of Ferric Sulfates  

NASA Astrophysics Data System (ADS)

A Mössbauer doublet assigned to ferric sulfate (Fe3D2) was identified in Paso Robles, Mars, spectra by Morris et al. (2006), who noted that its parameters are not diagnostic of any specific mineral because a number of different sulfates with varying parageneses might be responsible for this doublet. Work by Lane et al. (2008) used a multi-instrument approach based on Fe3+ sulfate spectra acquired with VNIR and midinfrared reflectance, mid-infrared emission and Mössbauer spectrometers to narrow down the possible ferric sulfate phases present at Paso Robles to ferricopiapite possibly mixed with other ferric sulfates such as butlerite, parabutlerite, fibroferrite, or metahomanite. Thus, we explore here the crystal-chemical rationale behind these interpretations of the Mössbauer results, using similarities and difference among mineral structures to explore which phases might have similar coordination polyhedra around the Fe atoms in sulfates. Work by Hawthorne et al. (2000) organizes the sulfate minerals into groups with analogous crystal structures. Mössbauer doublets assigned to ferric sulfates ubiquitously have isomer shifts (IS) of 0.40-53 mm/s so that IS is non-diagnostic. However, quadrupole splitting of doublets in these mineral groups has a wide range (0-1.4 mm/s) and the variation can be systematically correlated with different structure types. Members of the hydration series Fe2(SO4)3 · n H2O, which includes quenstedtite, coquimbite, paracoquimbite, kornelite, and lausenite have Mössbauer spectra that closely resemble singlets because of their near-zero QS. These minerals share structures involving finite clusters of sulfate tetrahedral and Fe octahedral or chains of depolymerized clusters, and all mineral species with these structures share similar Mössbauer parameters. At the other extreme, ferric sulfates with structures based on infinite sheets (hydrotalcite, alunite, jarosite), tend to have large electric field gradients at the nucleus of the Fe3+ cation, resulting in larger QS values (1-1.4 mm/s). Between these extremes of QS are two populations of structures based on finite clusters of polyhedra with QS = 0.36-0.80 mm/s (coquimbite, römerite, halotrichite, rozenite) and infinite chains with QS = 0.70-0.97 mm/s (chalcanthite, butlerite, fibroferrite, metahomanite). Our fits to the Paso Robles sol 429A data show two ferric doublets, both with IS = 0.42-0.43 mm/s but with differing QS = 0.36 and 0.93 mm/s; these parameters rule out mineral structures that have spectra with very high or very low QS. Ferric sulfates with structures composed of finite clusters and infinite chains thus provide the closest matches to the Paso Robles Mössbauer doublets, as well as spectra of other bright soils. Further constraints provided by other types of spectroscopy are then needed to determine which species within these structure groups are present. As additional sulfate structures are characterized, it will be possible to better understand the interrelationships among sulfate crystal structures and their spectral characteristics may provide additional constraints on mineral identification from ferric materials of all types. Morris et al. (2006) JGR, 111, doi: 10.1029/2005JE002584. Lane et al. (2008) Amer. Mineral., 93, 738-739. Hawthorne et al. (2000) Revs. Mineral., 40, 1-112.

Knutson, J.; Dyar, M. D.; Sklute, E. C.; Lane, M. D.; Bishop, J. L.

2008-12-01

361

Ferrous/ferric Mossbauer analysis of simulated nuclear waste glass with and without computer fitting  

SciTech Connect

Wet-chemical and /sup 57/Fe Mossbauer analyses of ferrous/ferric ratios in complex borosilicate and simple silicate glasses were compared. The results support the validity of the colorimetric wet-chemical procedure and establish a linear calibration for the Mossbauer data. The resulting correlation indicates that using area ratios from Mossbauer spectra will overestimate the proportion of ferrous iron by a factor of 1.2. The linear calibration was achieved only after statistically optimizing the peak line shape for each Mossbauer spectrum. Samples with a greater proportion of ferrous iron tended to have a greater Gaussian contribution to the peak line shape. A procedure to determine ferrous/ferric ratios from measured intensity data at three velocity locations was developed. With instrument modification, this result will lead to a substantial reduction in data collection time and the elimination of complex spectral fitting.

Goldman, D.S.; Bewley, D.E.

1985-12-01

362

FeII induced mineralogical transformations of ferric oxyhydroxides into magnetite of variable stoichiometry and morphology  

NASA Astrophysics Data System (ADS)

The Mössbauer spectroscopy was used to monitor the mineralogical transformations of ferrihydrite (F), lepidocrocite (L) and goethite (G) into magnetite as a function of aging time. Ferric oxyhydroxides were reacted with soluble FeII and OH- in stoichiometric amounts to form magnetite at an initial pH of ˜9.7. Observed transformation extent into magnetite followed the order: F>L>G with almost 30% of untransformed G after 1 month. The departure from stoichiometry, ?, of magnetite (Fe3-?O4) generated from F (?˜0.04) and L (?˜0.05) was relatively low as compared to that in magnetite from G (?˜0.08). The analysis by transmission electron microscopy and BET revealed that generated magnetite was also different in terms of morphology, particle size and surface area depending on the nature of initial ferric oxyhydroxide. This method of preparation is a possible way to form nano-sized magnetite.

Usman, M.; Abdelmoula, M.; Hanna, K.; Grégoire, B.; Faure, P.; Ruby, C.

2012-10-01

363

Purification of two muscle enzymes by chromatography on immobilized ferric ions.  

PubMed

Two enzymes, glycogen phosphorylase and lactate dehydrogenase, were purified simultaneously in a single step. Ferric ions immobilized on a chelating gel were used as the adsorbent. Adsorption and desorption steps were accomplished by changes in buffer composition. The recoveries were better than 80% and the capacities were about 5 mg of protein per milliliter of adsorbent. The procedure worked well both on a small and on a preparative scale. The homogeneity of the purified enzymes was checked by FPLC. PMID:2775499

Chaga, G; Andersson, L; Ersson, B; Porath, J

1989-08-01

364

Immunization of Cows with Ferric Enterobactin Receptor from Coliform Bacteria1  

Microsoft Academic Search

The serum and milk immunoglobulin (Ig) G responses of lactating dairy cows were determined following immunization with ferric enterobactin receptor FepA. Escherichia coli 471 was cultured in iron-depleted medium, and outer membrane proteins were extracted by 2% N-lauroylsarcosine sodium salt and 2% Triton X-100. The FepA was isolated from the outer membrane proteins by ion-exchange chromatog- raphy. Twenty cows were

J. Lin; J. S. Hogan; M. Aslam; K. L. Smith

1998-01-01

365

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

Microsoft Academic Search

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

Ching-Kuo Daniel Hsi; Donald Langmuir

1985-01-01

366

Modification of Tencel with Treatment of Ferric Sodium Tartrate Complex Solution I. Effect of Treatment Condition  

Microsoft Academic Search

Partial dissolution of cellulose by ferric sodium tartrate complex (FeTNa) solution was examined as refining treatment of the organic-solvent spun cellulose fiber (Tencel). The treatment conditions were discussed in terms of solvent strength, temperature, duration of the treatment, and free NaOH concentration by measuring the weight loss, crystallinity, and tenacity of the resultant yarns. For improving fibrillation resistance, the optimized

Katsuji Kasahara; Hiroaki Sasaki; Nobuo Donkai; Tohru Yoshihara; Tohru Takagishi

2001-01-01

367

The Ferric Enterobactin Transporter Fep Is Required for Persistent Salmonella enterica Serovar Typhimurium Infection.  

PubMed

Most bacterial pathogens require iron to grow and colonize host tissues. The Gram-negative bacterium Salmonella enterica serovar Typhimurium causes a natural systemic infection of mice that models acute and chronic human typhoid fever. S. Typhimurium resides in tissues within cells of the monocyte lineage, which limit pathogen access to iron, a mechanism of nutritional immunity. The primary ferric iron import system encoded by Salmonella is the siderophore ABC transporter FepBDGC. The Fep system has a known role in acute infection, but it is unclear whether ferric iron uptake or the ferric iron binding siderophores enterobactin and salmochelin are required for persistent infection. We defined the role of the Fep iron transporter and siderophores in the replication of Salmonella in macrophages and in mice that develop acute followed by persistent infections. Replication of wild-type and iron transporter mutant Salmonella strains was quantified in cultured macrophages, fecal pellets, and host tissues in mixed- and single-infection experiments. We show that deletion of fepB attenuated Salmonella replication and colonization within macrophages and mice. Additionally, the genes required to produce and transport enterobactin and salmochelin across the outer membrane receptors, fepA and iroN, are needed for colonization of all tissues examined. However, salmochelin appears to be more important than enterobactin in the colonization of the spleen and liver, both sites of dissemination. Thus, the FepBDGC ferric iron transporter and the siderophores enterobactin and salmochelin are required by Salmonella to evade nutritional immunity in macrophages and cause persistent infection in mice. PMID:23959718

Nagy, Toni A; Moreland, Sarah M; Andrews-Polymenis, Helene; Detweiler, Corrella S

2013-08-19

368

The determination of ferric iron in plants by HPLC using the microbial iron chelator desferrioxamine E.  

PubMed

Common methods for plant iron determination are based on atomic absorption spectroscopy, radioactive measurements or extraction with subsequent spectrophotometry. However, accuracy is often a problem due to background, contamination and interfering compounds. We here describe a novel method for the easy determination of ferric iron in plants by chelation with a highly effective microbial siderophore and separation by high performance liquid chromatography (HPLC). After addition of colourless desferrioxamine E (DFE) to plant fluids, the soluble iron is trapped as a brown-red ferrioxamine E (FoxE) complex which is subsequently separated by HPLC on a reversed phase column. The formed FoxE complex can be identified due to its ligand-to-metal charge transfer band at 435 nm. Alternatively, elution of both, DFE and FoxE can be followed as separate peaks at 220 nm wavelength with characteristic retention times. The extraordinarily high stability constant of DFE with ferric iron of K = 10(32) enables extraction of iron from a variety of ferrous and ferric iron compounds and allows quantitation after separation by HPLC without interference by coloured by-products. Thus, iron bound to protein, amino acids, citrate and other organic acid ligands and even insoluble ferric hydroxides and phosphates can be solubilized in the presence desferrioxamine E. The "Ferrioxamine E method" can be applied to all kinds of plant fluids (apoplasmic, xylem, phloem, intracellular) either at physiological pH or even at acid pH values. The FoxE complex is stable down to pH 1 allowing protein removal by perchloric acid treatment and HPLC separation in the presence of trifluoroacetic acid containing eluents. PMID:15865410

Fernández, Victoria; Winkelmann, Günther

2005-02-01

369

Using Crystal Structure Groups to Understand Mössbauer parameters of Ferric Sulfates  

Microsoft Academic Search

A Mössbauer doublet assigned to ferric sulfate (Fe3D2) was identified in Paso Robles, Mars, spectra by Morris et al. (2006), who noted that its parameters are not diagnostic of any specific mineral because a number of different sulfates with varying parageneses might be responsible for this doublet. Work by Lane et al. (2008) used a multi-instrument approach based on Fe3+

J. Knutson; M. D. Dyar; E. C. Sklute; J. L. Bishop

2008-01-01

370

Characterisation of aqueous ferric chloride etchants used in industrial photochemical machining  

Microsoft Academic Search

Ferric chloride (FeCl3) is the most commonly used etchant for photochemical machining (PCM) but there is a great variety in the grades of the commercial product. This paper aims at defining standards for industrial etchants (that are not chemically pure) and methods by which they are analysed and monitored.In an ideal world, to maintain a constant rate of etching and

David M. Allen; Heather J. A. Almond

2004-01-01

371

Viscosity of liquid ferric sulfate solutions and application to the formation of gullies on Mars  

Microsoft Academic Search

We studied the viscosity of ferric sulfate Fe2(SO4)3 solutions as a model for low-temperature liquids on the surface of Mars and their implication in the formation of gullies. Viscosity varies with temperature and concentration, ranging from 7.0 × 10?3 Pa s for 38.8 wt % at 285.15 K to 4.6 Pa s for 58.2 wt % at 260.15 K. Using

Vincent F. Chevrier; Richard Ulrich; Travis S. Altheide

2009-01-01

372

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

Microsoft Academic Search

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

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

1999-01-01

373

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

Microsoft Academic Search

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

S. M. Macfie; A. A. Crowder

1987-01-01

374

Iron sucrose causes greater proteinuria than ferric gluconate in non-dialysis chronic kidney disease  

Microsoft Academic Search

Non-dextran intravenous (i.v.) iron preparations seem to differentially affect proteinuria in patients with chronic kidney disease. To study effects of ferric gluconate and iron sucrose on proteinuria, we conducted a crossover trial in 12 patients with stage 3–4 chronic kidney disease. These patients were randomized to receive the same dose of either drug 1 week apart. Urine samples were obtained

R Agarwal; A R Rizkala; M O Kaskas; R Minasian; J R Trout

2007-01-01

375

Glyphosate Inhibition of Ferric Reductase Activity in Iron Deficient Sunflower Roots  

Microsoft Academic Search

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

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

2008-01-01

376

Features of ferric sulfate precipitates formed by different cultivations of Acidithiobacillus ferrooxidans  

Microsoft Academic Search

This study focused on the ferric sulfate precipitates formed during the culture of Acidithiobacillus ferrooxidans (A. ferrooxidans) in a modified 9K medium by applying a potential control on the electrode. X-ray diffraction (XRD), environmental scanning\\u000a electron microscope (ESEM), Raman spectroscopy (Raman) and Fourier Transform Infrared spectroscopy (FTIR) were carried out\\u000a to characterize and identify the precipitates which were formed, respectively,

Xin Wang; Anhuai Lu; Changqiu Wang

2010-01-01

377

Expression, isolation and properties of Fur (ferric uptake regulation) protein of Escherichia coli K 12  

Microsoft Academic Search

Summary The clonedfur (ferric uptake regulation) gene ofEscherichia coli K12 was ligated to an expression vector which was inducible with nalidixic acid. The Fur protein was isolated in a single step by immobilized metal-ion-affinity chromatography over zinc iminodiacetate agarose. The amino acid composition of the isolated protein agreed with that predicted from the gene sequence and indicated post-transcriptional removal of

Sechan Wee; J. B. Neilands; Michael L. Bittner; Bruce C. Hemming; Barry L. Haymore; Ramnath Seetharam

1988-01-01

378

Fabrication and Characterization of Novel Salicylic Acid Sensors Using Different Reagents (Ferric and Copper)  

Microsoft Academic Search

Fabrication of optical fiber salicylic acid (SA) sensors based on immobilization of ferric(III) nitrate and copper(II) acetate on Dowex?50x8 is presented in this paper. The SA forms a stable purple complex with immobilized Fe at pH 2.1 with a response time of 10 min while it forms a stable yellowish green complex with immobilized Cu at pH 6.5 with a response

Han Chern Loh; Musa Ahmad; Mohd Nasir Taib

2006-01-01

379

Reduction of organically complexed ferric iron by superoxide in a simulated natural water.  

PubMed

Superoxide (and potentially its conjugate acid hydroperoxyl) is unique among the reactive oxygen species in that its standard redox potential in circumneutral natural waters potentially allows it to reduce ferric iron to the more soluble ferrous state. Here we have observed the superoxide/ hydroperoxyl-mediated reduction of ferric complexes with a variety of synthetic organic ligands and several complexes with natural organic matter (NOM), as well as freshly precipitated amorphous ferric oxyhydroxide, in bicarbonate buffered solutions at pH 8.1. From measurements of superoxide decay in the presence of the complexes, we calculated second-order rate constants for superoxide/ hydroperoxyl-mediated reduction that vary from (9.3+/-0.2) x 10(3) M(-1) s(-1) for the complex between Fe(III) and desferrioxamine B up to (1.9+/-0.2) x 10(5) M(-1) s(-1) for Fe(III)-salicylate and (2.3+/-0.1) x 10(5) M(-1) s(-1) for one of the Fe(III)-NOM complexes. We also verified that ferrous iron was produced from superoxide/hydroperoxyl-mediated Fe(III) reduction using ferrozine to trap free Fe(II). Low yields of the ferrozine complex when compared to the measured rates of superoxide decay suggest that ferric complexes are reduced directlyto corresponding ferrous complexes, with much of the ferrous complex reoxidizing before it is able to release free ferrous iron. This is an important consideration for microorganisms, as the kinetics of trace metal uptake is typically governed by free ion activity. PMID:15884361

Rose, Andrew L; Waite, T David

2005-04-15

380

Determination of the molar extinction coefficient for the ferric reducing\\/antioxidant power assay  

Microsoft Academic Search

The FRAP reagent contains 2,4,6-tris(2-pyridyl)-s-triazine, which forms a blue–violet complex ion in the presence of ferrous ions. Although the FRAP (ferric reducing\\/antioxidant power) assay is popular and has been in use for many years, the correct molar extinction coefficient of this complex ion under FRAP assay conditions has never been published, casting doubt on the validity of previous calibrations. A

William A. Hayes; Daniel S. Mills; Rachel F. Neville; Jenna Kiddie; Lisa M. Collins

2011-01-01

381

Effects of electrolytes and curing on freezing of ferric hydroxide sludge  

Microsoft Academic Search

This work elucidates how the electrolytes and curing time affect freezing and thawing treatment of ferric hydroxide sludge. The sludge is frozen at a freezing temperature of ?16.5°C with addition of one of the following four electrolytes: sodium sulfate (Na2SO4), potassium nitrate (KNO3), sodium nitrate (NaNO3) and sodium chloride (NaCl). Although the eutectic temperatures for the former two and latter

D. S Jean; D. J Lee

2000-01-01

382

Full Scale Evaluation on Ferric Flocs Sludge Treatment with Pelleting Flocculation Blanket Process  

Microsoft Academic Search

The Pelleting Flocculation Blanket (PFB) process is a newly developed technology for high concentration suspensions removal characterized by high surface loading solid-liquid separation. In this paper, by using the PFB process, a pilot-scale experimental study was carried out on concentrating ferric flocs sludge with a full scale of 19~38 m3\\/H. The investigation aimed to optimize the operational conditions. Under the

Zhang Gang; Huang Ting-lin; Li Zhan-peng; Tan Chi

2010-01-01

383

Ferric reduction by foots of chlorotic bean plants: Indications for an enzymatic process  

Microsoft Academic Search

Reduction of chelated ferric ions by the roots of iron?stressed bean plants showed kinetics characteristic for reactions catalyzed by matrix?bound enzymes. Assays for iron reducing compounds in the medium in which those plants had been standing for 1 day failed to yield indications for soluble reductants produced by iron?stressed plants. The results suggest that the capacity to reduce chelated iron

H. F. Bienfait; J. Duivenvoorden; W. Verkerke

1982-01-01

384

Bioreduction of ferric species and biogenesis of green rusts in soils  

NASA Astrophysics Data System (ADS)

Iron-reducing bacteria (IRB) communities are widespread and numerous in all main types of soils. IRB are involved efficiently and significantly in the reduction of ferric species and the weathering of iron-bearing minerals under the dependence of physical, chemical, biological parameters. They appear as the major biological agent promoting the formation of green rust mineral (GR) in hydromorphic soils (Gleysols). To cite this article: J. Berthelin et al., C. R. Geoscience 338 (2006).

Berthelin, Jacques; Ona-Nguema, Georges; Stemmler, Sébastien; Quantin, Cécile; Abdelmoula, Mustapha; Jorand, Frédéric

2006-06-01

385

Characterization of a water-in-oil microemulsion containing a concentrated ammonium ferric sulfate aqueous phase  

Microsoft Academic Search

A water-in-oil (w\\/o) microemulsion containing high concentrations of ammonium ferric sulfate in solution was characterized by SAXS, EXAFS, electrical conductivity, and viscosity measurements and by its phase behavior. The nanometer-sized aqueous droplets are microemulsified by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in an isooctane continuous phase. Addition of small amounts of sodium dodecyl sulfate (SDS) as a cosurfactant greatly aids in the

John G. Darab; David M. Pfund; John L. Fulton; John C. Linehan; Malcolm Capel; Yanjun Ma

1994-01-01

386

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

SciTech Connect

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.

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

1988-06-01

387

Characterization of a water-in-oil microemulsion containing a concentrated ammonium ferric sulfate aqueous phase  

SciTech Connect

A water-in-oil (w/o) microemulsion containing high concentrations of ammonium ferric sulfate in solution was characterized by SAXS, EXAFS, electrical conductivity, and viscosity measurements and by its phase behavior. The nanometer-sized aqueous droplets are microemulsified by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in an isooctane continuous phase. Addition of small amounts of sodium dodecyl sulfate (SDS) as a cosurfactant greatly aids in the solubilization of the inorganic electrolyte-laden aqueous phase. For this five-component system there is a large region of the composition phase space that exists as a clear, stable w/o microemulsion. A portion of this w/o microemulsion phase space can be characterized as spherically shaped aqueous nanometer-sized droplets. A simple relationship between the total surfactant concentration and the amount of water on the droplet size was established. This relationship has the same form as the well-known relationship for the ternary system, AOT/water/isooctane. True thermodynamic equilibrium was not established in this microemulsion study because the reaction times for the various ferric oxyhydroxide species are prohibitively long. As a result, pseudoequilibria for this ammonium ferric sulfate microemulsion are reported. 31 refs., 7 figs., 1 tab.

Darab, J.G.; Pfund, D.M.; Fulton, J.L.; Linehan, J.C. (Pacific Northwest Lab., Richland, WA (United States)); Capel, M. (Brookhaven National Lab., Upton, NY (United States)); Ma, Y. (Univ. of Washington, Seattle, WA (United States))

1994-01-01

388

Ferric coagulant recovered from coagulation sludge and its recycle in chemically enhanced primary treatment.  

PubMed

An investigation was conducted to study the feasibility of ferric coagulant recovery from chemical sludge and its recycle in chemically enhanced primary treatment (CEPT) to make the process more cost-effective, as well as reduce sludge volume. The optimum conditions and efficiency of the acidification for ferric coagulant recovery from coagulation sludge were investigated. Experimental results showed that the recovered coagulants can be used in CEPT and the pollutants removal efficiency is similar to that of fresh coagulant, and for some aspects the effect of recovered coagulants is better than that of fresh ones, such as turbidity removal. Although some substances will be enriched during recycle, they have little effect on treated wastewater quality. Acidification condition also had significant influence on reduction of sludge volume. The efficiency of coagulant recovery had a linear relationship with sludge reduction. Experiments verify that it would be a sustainable and cost-effective way to recover ferric coagulant from coagulation sludge in water treatment and chemical wastewater treatment, and then recycle it to CEPT, as well as reduce sludge volume. PMID:19587418

Xu, G R; Yan, Z C; Wang, N; Li, G B

2009-01-01

389

Orthophosphate removal from a synthetic wastewater using lime, alum, and ferric chloride  

SciTech Connect

Lime, alum, and ferric chloride were evaluated using a series of jar tests to determine their effectiveness in orthophosphate precipitation from synthetic wastewaters. Calcium phosphate precipitation was most efficient at pH 11.0 and a total carbonate to phosphorus, C/sub T/:P, molar ratio of 15.0. For these conditions, a residual total orthophosphate concentration of 0.12 mg/L-P was observed. The Mg:P molar ratio had little effect on orthophosphate removal from the synthetic wastewater. When alum was used, the minimum residual total orthophosphate concentration observed was 0.21 mg/L-P for an Al:P molar ratio of 3.0 and a pH of 6.0 when pH was adjusted before and during alum addition. When ferric chloride was used, it was found that an Fe:P molar ratio of 3.0 and a pH of 6.0 resulted in the lowest residual total orthophosphate concentration. This value was 0.19 mg/L-P when pH was adjusted before and during iron addition. A multiple regression analysis produced mathematical relationships which can be used to predict residual soluble and residual total orthophosphate concentration for lime, alum, and ferric chloride treatment.

Sisk, L.; Benefield, L.; Reed, B.

1987-01-01

390

Formate binding to ferric wild type and mutant myoglobins thermodynamic and X-ray crystallographic study.  

PubMed

The X-ray crystal structure of the formate derivative of ferric loggerhead sea turtle (Caretta caretta) Mb has been determined at 2.0 A resolution (R = 0.164) by difference Fourier techniques. Formate, sitting in the central part of the heme distal site, is coordinated to the heme iron as unidentate ligand, through the O1 oxygen atom, and is hydrogen bonded to the distal His64(E7) NE2 atom through O2. Thermodynamics for formate binding to ferric loggerhead sea turtle Mb, sperm whale Mb, Aplysia limacina Mb, as well as to the VR and VRS mutants of sperm whale Mb were obtained between pH 4.5 and 8.5, at 20.0 degrees C. These results, representing the first structure of a ferric hemoprotein:formate complex solved by X-ray crystallography, outline the role of amino acid residues at positions E7, F8 and E10 in modulating ligand binding properties of oxygen carrying proteins. PMID:7835416

Leci, E; Brancaccio, A; Cutruzzolà, F; Allocatelli, C T; Tarricone, C; Bolognesi, M; Desideri, A; Ascenzi, P

1995-01-01

391

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

Microsoft Academic Search

`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

Seth Rose; W. Crawford Elliott

2000-01-01

392

Ferric chelate reduction by sunflower ( Helianthus annuus L.) leaves: influence of light, oxygen, iron-deficiency and leaf age  

Microsoft Academic Search

The presence of ferric chelate reducing activity in sunflower (Helianthus annuus L.) leaves has been studied by submerging leaf discs in a solution with Fe(lll)-ethylenediaminetetra-acetate (FeEDTA), batho- phenanthroline disulphonate (BPDS) and vacuum infil- tration. The effect of different factors on the Fe(lll) reduction rate was studied. Ferric reduction rate was about 10-fold higher in the light than in darkness. The

Manuel D. de la Guardia; Esteban Alc´ntara

1996-01-01

393

Usage of Artificial Neural Network (Back Propagation) in Optimising Salicylic Acid Determination with Ferric(III) Nitrate  

Microsoft Academic Search

The use of artificial neural networks (ANN) in optimizing salicylic acid (SA) determination is presented in this paper. A simple and rapid spectrophotometric method for salicylic acid (SA) determination was carried out based on the complexation of salicylic acid–ferric(III) nitrate, SAFe(III). The SA forms a stable purple complex with ferric(III) nitrate at pH 2.45. The useful dynamic linear range is

Han Chern Loh; Musa Ahmad; Mohd Nasir Taib

2006-01-01

394

Uptake of Iron by Isolated Rat Hepatocytes from a Hydrophilic Impermeant Ferric Chelate, Fe(III)DTPA  

Microsoft Academic Search

We studied uptake of iron from Fe(III)–diethylenetriamine pentaacetate (DTPA) in isolated rat hepatocytes. This uptake is specific with an affinity of 600 nMand shows an optimum pH of 6. The specificity is indicated by inhibition by ferric citrate and diferric transferrin. Iron uptake from Fe(III)–DTPA is completely inhibited by trypsinization of the cell surface, by strong impermeant ferric chelators (DTPA,

Barbara Scheiber; Hans Goldenberg

1996-01-01

395

Low Temperature Photo-Oxidation of Chloroperoxidase Compound II  

PubMed Central

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.

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

2010-01-01

396

Speciation characterization and coagulation of poly-silica-ferric-chloride: the role of hydrolyzed Fe(III) and silica interaction.  

PubMed

The highly efficient inorganic polymer flocculants (IPFs) of the ferric-silica system is a new and promising coagulant. Interactions between ferric species and silica play a large part in the coagulation of suspensions. These effects are quite distinct from those associated with polymeric or colloid silica. However, although these species are key to coagulation efficiency, they have not been comprehensively discussed. A new type of coagulant, poly-silica-ferric-chloride (PFSC), was synthesized by co-polymerization and characterized by time complexation spectroscopy and photon correlation spectroscopy. Compared with traditional ferric salt, the results indicated that PFSC had a higher molecular weight, lesser positive charge, lower Fe(b) and higher Fe(c). The higher the Si/Fe ratio, the higher the silica and lower the silica(c) found. The PFSC with appropriate polysilica acid not only obtained better coagulation/flocculation efficiency in turbidity removal, enhanced the flocculation index (FI) and provided less residual ferric, it also lowered water treatment costs compared to traditional ferric salt. Results showed that PFSC could remove colloid particles in water by charge neutralization and sweeping, adsorption bridging mechanism. PMID:21790046

Shi, Jian; Zhang, Yan; Zou, Kaiyun; Xiao, Feng

2011-01-01

397

Reduced adsorption of ametryn in clay, humic acid, and soil by interaction with ferric ion under Fenton treatment conditions.  

PubMed

Previous work in our laboratory indicated a weak interaction between ferric ion and several triazine/triazinone herbicides during a Fenton treatment process, and the intensity of the interaction was calculated. To further support the existence of this weak interaction, the adsorption of ametryn, a triazine herbicide, was investigated in kaolinite clay, humic acid, and soil under pseudo-Fenton conditions. At a low addition rate of ferric ion, the adsorption of ametryn in clay, humic acid, and soil was enhanced due to the decreased pH resulting from the hydrolysis of ferric ion. But the pH effect was totally neutralized and the adsorption of ametryn was significantly reduced by further addition of ferric ion, demonstrating the existence of the weak interaction between ametryn and ferric acid. Further study showed that the adsorption-reduction effect of ferric ion existed not only with ametryn but also with several other triazine/triazinone herbicides. This weak interaction may accelerate the desorption process during the remediation of triazine/triazinone herbicide-contaminated soil using a Fenton/Fenton-like treatment, but it may also impede the degradation of these herbicides. PMID:16484083

Wang, Qiquan; Lemley, Ann T

2006-01-01

398

Ferric, not ferrous, heme activates RNA-binding protein DGCR8 for primary microRNA processing  

PubMed Central

The RNA-binding protein DiGeorge Critical Region 8 (DGCR8) and its partner nuclease Drosha are essential for processing of microRNA (miRNA) primary transcripts (pri-miRNAs) in animals. Previous work showed that DGCR8 forms a highly stable and active complex with ferric [Fe(III)] heme using two endogenous cysteines as axial ligands. Here we report that reduction of the heme iron to the ferrous [Fe(II)] state in DGCR8 abolishes the pri-miRNA processing activity. The reduction causes a dramatic increase in the rate of heme dissociation from DGCR8, rendering the complex labile. Electronic absorption, magnetic circular dichroism, and resonance Raman spectroscopies indicate that reduction of the heme iron is accompanied by loss of the cysteines as axial ligands. ApoDGCR8 dimers, generated through reduction and removal of the heme, show low levels of activity in pri-miRNA processing in vitro. Importantly, ferric, but not ferrous, heme restores the activity of apoDGCR8 to the level of the native ferric complex. This study demonstrates binding specificity of DGCR8 for ferric heme, provides direct biochemical evidence for ferric heme serving as an activator for miRNA maturation, and suggests that an intracellular environment increasing the availability of ferric heme may enhance the efficiency of pri-miRNA processing.

Barr, Ian; Smith, Aaron T.; Chen, Yanqiu; Senturia, Rachel; Burstyn, Judith N.; Guo, Feng

2012-01-01

399

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

SciTech Connect

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.

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

1999-12-13

400

Direct Observation of the Low-Spin Fe(III)-NO(radical) Intermediate State during Rebinding of NO to Photodeligated Ferric Cytochrome c.  

PubMed

Nitrosylated ferric heme is autoreduced readily to the more stable Fe(II)-NO adduct, but it is stabilized in NO-carrier heme proteins where maintaining the Fe(III) oxidation state is crucial for efficient NO delivery. Density functional theory calculations by Lehnert and co-workers have shown that a NO-bound ferric model heme has a low-spin (LS) Fe(III)-NO(radical) state that might be critical for efficient NO transport by NO-carrier heme proteins. Recently, the elusive LS Fe(III)-NO(radical) state was observed as an electronic intermediate state during geminate rebinding (GR) of NO to ferric myoglobin (Mb(III)). Cytochrome c (Cytc), a ubiquitous heme protein, is useful for generalizing the presence of the LS Fe(III)-NO(radical) state. Photoexcitation dynamics of NO-bound ferric Cytc (Cytc(III)NO) was probed after excitation of Cytc(III)NO in D2O solution at 294 K with a 575 nm pulse using femtosecond vibrational spectroscopy. The time-resolved spectra displayed several weak absorption bands in the 1900-1800 cm(-1) range and a dominant bleach at 1917 cm(-1), the position of the absorption at equilibrium. Two absorptions, with 37 cm(-1) isotope shift of (15)NO, shifted toward higher energy and narrowed with an average time constant of 8 ps, indicating that they arose from thermally and/or vibrationally excited NO in the ground electronic state of Cytc(III)NO. Three absorption bands, showing 33 cm(-1) isotope shift of (15)NO and peaked at 1865, 1836, and 1807 cm(-1), were assigned to the deligated NO residing in the interior of the protein, to the rebound Cytc(III)NO in the LS Fe(III)-NO(radical) state, and to the vibrationally excited NO of Cytc(III)NO in the LS Fe(III)-NO(radical) state, respectively. The quantum yield for NO deligation of Cytc(III)NO by a 575 nm photon was 0.8 ± 0.1. Most of the deligated NO showed non-exponential GR, and the GR kinetics was described by exp(-(t/7 ps)(0.7)). Every rebound Cytc(III)NO formed the LS Fe(III)-NO(radical) state that relaxed into the ground state, with the relaxation kinetics described by exp(-(t/2.5 ps)(0.7)). The GR of NO to ferric Cytc was as fast as the thermal relaxation of hot heme, and the relaxation of the rebound Cytc(III)NO in the intermediate LS Fe(III)-NO(radical) state was faster than the thermal relaxation of hot heme, generating the rebound Cytc(III)NO in a thermally excited ground electronic state. For both Cytc(III)NO and Mb(III)NO, the relaxation rate of the LS Fe(III)-NO(radical) state was similar to the upper rate limit of the domed-to-planar heme transition observed in NO-rebound ferrous-heme proteins, suggesting that the change in the Fe-NO bond length is coupled to the doming motion of the heme Fe. PMID:24041332

Park, Jaeheung; Lee, Taegon; Lim, Manho

2013-09-30

401

Ferric iron in orogenic lherzolite massifs and controls of oxygen fugacity in the upper mantle  

NASA Astrophysics Data System (ADS)

The bulk Fe2O3 contents and inter-mineral distributions of Fe3+ were investigated in a suite of samples from several orogenic lherzolite massifs, including Beni Bousera (Morocco), Ronda (Spain) and Lherz (France). Ferric iron contents were determined for each phase by Mössbauer spectroscopy and these results were combined with microprobe data and modal abundances to determine the bulk Fe2O3 contents. The notion that Fe3+ is moderately incompatible during partial melting in the mantle is supported by the observed decrease in bulk Fe2O3 content with increasing MgO, as well as by the generally lower Fe3+ content of clinopyroxene in samples with low modal abundances of this phase. The partitioning of Fe3+ between orthopyroxene and clinopyroxene is consistent with literature data for spinel peridotite xenoliths. The partitioning of Fe3+ between clinopyroxene and spinel is composition dependent, changing with the Cr/Al of spinel. Thus partitioning is expected to be different in the spinel peridotite and plagioclase peridotite facies of the upper mantle. The ƒO2 of orogenic massifs varies over several log units relative to the FMQ buffer. The values recorded by spinel-based and clinopyroxene-based oxygen barometry are generally comparable, indicating redox equilibrium between these two phases even at the relatively low temperature conditions existing in parts of the lithospheric mantle. Calculated bulk Fe2O3 contents range from 0.03 to 0.27 wt.%. The combination of modal abundance and major element composition means that orthopyroxene is a major contributor to the bulk Fe2O3 budget of peridotites, although clinopyroxene and spinel are much richer in Fe3+ on a per formula unit basis. Residual Cr-rich spinel is the dominant source of Fe3+ in plagioclase peridotites. In terms of the geochemical behaviour of Fe3+, it can be concluded that orogenic peridotites exhibit essentially the same behaviour as spinel peridotite xenoliths. In terms of the controlling factors of ƒO2 in the upper mantle, our data set records a certain degree of decoupling of ƒO2 from whole rock Fe2O3 content, even if a correlation between these two parameters is generally apparent. This decoupling is because, whereas both whole rock Fe2O3 content and ƒO2 are influenced by partial melting and melt extraction, additional processes such as metasomatism and phase changes can effectively reset ƒO2 without always causing a concomitant change in bulk Fe2O3 content. Modelling the oxidation of spinel reveals that the ƒO2 can be readily reset under initially reducing conditions, but the incorporation of progressively more and more Fe3+ in spinel is required to further raise ƒO2. A quasi-limit of ?logƒO2 = FMQ + 1 is expected. These results are consistent with the general redox behaviour observed for spinel peridotites. Our data imply that Fe3+ Fe2+ equilibria have an important, if not dominant influence on ƒO2 in the spinel peridotite facies of the upper mantle.

Woodland, A. B.; Kornprobst, J.; Tabit, A.

2006-06-01

402

Reactions of metal ions at surfaces of hydrous iron oxide  

USGS Publications Warehouse

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

Hem, J. D.

1977-01-01

403

Anodic oxidation of pyrrhotite in simulated CIP liquors  

Microsoft Academic Search

Natural pyrrhotite (Fe7S8) can be oxidized in alkali (pH 10) at 25°C at potentials above ?0.2 V (SCE). The voltammetry of a ground pyrrhotite disc shows current peaks consistent with the formation of a ferric surface phase such as Fe(OH)3 by air oxidation or by potentiostatic oxidation. In unbuffered solution, proton production can be demonstrated implicating the formation of sulfate,

H. G. Linge

1995-01-01

404

Effects of sulfur containing amino acids on iron and nitric oxide stimulated catecholamine oxidation  

Microsoft Academic Search

Summary.  ?Taurine is a free amino acid found in high concentrations in tissues containing catecholamines. The ability of taurine and\\u000a its metabolic precursors to inhibit or stimulate catecholamine oxidation and subsequent quinone formation was examined. Ferric\\u000a chloride was used as the catalyzing agent to stimulate L-dopa or norepinephrine oxidation and NO donors were also examined\\u000a for their actions to stimulate quinone

M. Biasetti; R. Dawson Jr.

2002-01-01

405

Quantification of ferrous/ferric ratios in minerals: new evaluation schemes of Fe L23 electron energy-loss near-edge spectra  

NASA Astrophysics Data System (ADS)

Determination of Fe3+/?Fe in minerals at submicrometre scale has been a long-standing objective in analytical mineralogy. Detailed analysis of energy-loss near-edge structures (ELNES) of the Fe L23 core-loss edges recorded in a transmission electron microscope (TEM) provides chemical information about the iron oxidation state. The valence-specific multiplet structures are used as valence fingerprints. Systematic investigations on the Fe L23 ELNES of mono and mixed-valence Fe-bearing natural minerals and synthetic solid solutions of garnets (almandine-skiagite and andradite-skiagite), pyroxenes (acmite-hedenbergite) and spinels (magnetite-hercynite) are presented where the presence of multiple valence states is distinguished by a splitting of the Fe L3 edge. We demonstrate the feasibility of quantification of the ferrous/ferric ratio in minerals by analyzing the Fe L23 ELNES as a function of the ferric iron concentration resulting in three independent methods: (1) The method of the modified integral intensity ratio of the Fe L23 white lines employs two 2-eV-wide integration windows centring around both the Fe L3 maximum for Fe3+ and the Fe L2 maximum for Fe2+. This refined routine, compared to the previously published quantification method of the ferrous/ferric ratio in minerals, leads to an improved universal curve with acceptable absolute errors of about +/-0.03 to +/-0.04 for Fe3+/?Fe ratios. (2) The second method uses a simple mathematical description of the valence-dependent splitting of Fe L3 ELNES by fitting several Gaussian functions and an arctan function. The systematic analysis of the integral portions of the individual Gaussian curves for different mineral groups provides a further Fe3+/?Fe quantification method with an absolute error of about +/-0.02 to +/-0.03. (3) The Fe L3 ELNES can also be modelled with the help of reference spectra, whereby the Fe3+/?Fe ratio can be determined with an absolute error of ca. +/-0.02.

van Aken, P. A.; Liebscher, B.

406

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

PubMed Central

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.

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

1999-01-01

407

Geometry dependence of intramolecular photoinduced electron transfer in synthetic zinc-ferric hybrid diporphyrins  

SciTech Connect

Despite the crucial role of photoinduced electron transfer (ET) reactions in photosynthetic energy conversion, the factors that control this reactivity remain poorly understood. Recent theoretical work indicates the importance of orientation effects on the rates of the nonadiabatic ET process between diporphyrin pairs. This paper reports more comprehensive geometric effects in an extensive array of hybrid metal complexes consisting of zinc porphyrin (ZnP) and ferric porphyrin chloride (Fe{sup III}PCl). Diporphyrin models studied here include a variety of mutual orientations and different kinds of aromatic spacers such as benzene, naphthalene, and spirobiindan.

Osuka, Atsuhiro; Maruyama, Kazuhiro (Kyoto Univ. (Japan)); Mataga, Noboru; Asahi, Tsuyoshi (Osaka Univ. (Japan)); Yamazaki, Iwao; Tamai, Naoto (Hokkaido Univ., Sapporo (Japan))

1990-06-06

408

Surface topology of the Escherichia coli K-12 ferric enterobactin receptor.  

PubMed Central

Monoclonal antibodies (MAb) were raised to the Escherichia coli K-12 ferric enterobactin receptor, FepA, and used to identify regions of the polypeptide that are involved in interaction with its ligands ferric enterobactin and colicins B and D. A total of 11 distinct FepA epitopes were identified. The locations of these epitopes within the primary sequence of FepA were mapped by screening MAb against a library of FepA::PhoA fusion proteins, a FepA deletion mutant, and proteolytically modified FepA. These experiments localized the 11 epitopes to seven different regions within the FepA polypeptide, including residues 2 to 24, 27 to 37, 100 to 178, 204 to 227, 258 to 290, 290 to 339, and 382 to 400 of the mature protein. Cell surface-exposed epitopes of FepA were identified and discriminated by cytofluorimetry and by the ability of MAb that recognize them to block the interaction of FepA with its ligands. Seven surface epitopes were defined, including one each in regions 27 to 37, 204 to 227, and 258 to 290 and two each in regions 290 to 339 and 382 to 400. One of these, within region 290 to 339, was recognized by MAb in bacteria containing intact (rfa+) lipopolysaccharide (LPS); all other surface epitopes were susceptible to MAb binding only in a strain containing a truncated (rfaD) LPS core, suggesting that they are physically shielded by E. coli K-12 LPS core sugars. Antibody binding to FepA surface epitopes within region 290 to 339 or 382 to 400 inhibited killing by colicin B or D and the uptake of ferric enterobactin. In addition to the FepA-specific MAb, antibodies that recognized other outer membrane components, including Cir, OmpA, TonA, and LPS, were identified. Immunochemical and biochemical characterization of the surface structures of FepA and analysis of its hydrophobicity and amphilicity were used to generate a model of the ferric enterobactin receptor's transmembrane strands, surface peptides, and ligand-binding domains. Images

Murphy, C K; Kalve, V I; Klebba, P E

1990-01-01

409

Ferric ion as a scavenging agent in a solvent extraction process  

DOEpatents

Ferric ions are added into the aqueous feed of a plutonium scrap recovery process that employs a tributyl phosphate extractant. Radiolytic degradation products of tributyl phosphate such as dibutyl phosphate form a solid precipitate with iron and are removed from the extraction stages via the waste stream. Consequently, the solvent extraction characteristics are improved, particularly in respect to minimizing the formation of nonstrippable plutonium complexes in the stripping stages. The method is expected to be also applicable to the partitioning of plutonium and uranium in a scrap recovery process.

Bruns, Lester E. (Kennewick, WA); Martin, Earl C. (Richland, WA)

1976-01-01

410

Iron acquisition systems for ferric hydroxamates, haemin and haemoglobin in Listeria monocytogenes.  

PubMed

Listeria monocytogenes is a Gram-positive bacterium that causes severe opportunistic infections in humans and animals. We biochemically characterized, for the first time, the iron uptake processes of this facultative intracellular pathogen, and identified the genetic loci encoding two of its membrane iron transporters. Strain EGD-e used iron complexes of hydroxamates (ferrichrome and ferrichrome A, ferrioxamine B), catecholates (ferric enterobactin, ferric corynebactin) and eukaryotic binding proteins (transferrin, lactoferrin, ferritin, haemoglobin). Quantitative determinations showed 10-100-fold lower affinity for ferric siderophores (Km approximately 1-10 nM) than Gram-negative bacteria, and generally lower uptake rates. Vmax for [59Fe]-enterobactin (0.15 pMol per 10(9) cells per minute) was 400-fold lower than that of Escherichia coli. For [59Fe]-corynebactin, Vmax was also low (1.2 pMol per 10(9) cells per minute), but EGD-e transported [59Fe]-apoferrichrome similarly to E. coli (Vmax=24 pMol per 10(9) cells per minute). L. monocytogenes encodes potential Fur-regulated iron transporters at 2.031 Mb (the fur-fhu region), 2.184 Mb (the feo region), 2.27 Mb (the srtB region) and 2.499 Mb (designated hupDGC region). Chromosomal deletions in the fur-fhu and hupDGC regions diminished iron uptake from ferric hydroxamates and haemin/haemoglobin respectively. In the former locus, deletion of fhuD (lmo1959) or fhuC (lmo1960) strongly reduced [59Fe]-apoferrichrome uptake. Deletion of hupC (lmo2429) eliminated the uptake of haemin and haemoglobin, and decreased the virulence of L. monocytogenes 50-fold in mice. Elimination of srtB region genes (Deltalmo2185, Deltalmo2186, Deltalmo2183), both sortase structural genes (DeltasrtB, DeltasrtA, DeltasrtAB), fur and feoB did not impair iron transport. However, deletion of bacterioferritin (Deltafri, lmo943; 0.97 Mb) decreased growth and altered iron uptake: Vmax of [59Fe]-corynebactin transport tripled in this strain, whereas that of [59Fe]-apoferrichrome decreased 20-fold. PMID:16430693

Jin, Bo; Newton, Salete M C; Shao, Yi; Jiang, Xiaoxu; Charbit, Alain; Klebba, Phillip E

2006-02-01

411

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

SciTech Connect

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.

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

2007-09-01

412

Mossbauer Spectroscopic Study of the Reversible Oxidation of Ferrous Ions in Y Zeolite.  

National Technical Information Service (NTIS)

The ferrous ions in dehydrated Fe(2+)-Y zeolite are oxidized to ferric ions by the adsorption of dry oxygen at 400C. Approximately one oxygen atom is adsorbed for two iron ions. It is proposed that the oxidation at 400C forms iron-oxygen-iron bridges insi...

M. Boudart R. L. Garten W. N. Delgass

1969-01-01

413

Iron-Titanium Oxides and Oxygen Fugacities in Volcanic Rocks  

Microsoft Academic Search

It is shown that in silicate liquids the ferric-ferrous equilibrium is controlled by temperature, oxygen fugacity, and the composition of the liquid, particularly its alkali content. Thus, if the iron-titanium oxide minerals that precipitate from a silicate liquid reflect the ferricferrous equilibrium, the oxygen geobarometer of Buddington and Lindsley will have to be calibrated, especially for such volcanics as phonolites

I. S. E. Carmichael; J. Nicholls

1967-01-01

414

Ferric reductase of Saccharomyces cerevisiae: molecular characterization, role in iron uptake, and transcriptional control by iron.  

PubMed Central

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

Dancis, A; Roman, D G; Anderson, G J; Hinnebusch, A G; Klausner, R D

1992-01-01

415

Metribuzin degradation by membrane anodic Fenton treatment and its interaction with ferric ion.  

PubMed

Metribuzin, a widely used herbicide and a frequently detected pollutant in the environment, was studied as a target compound for membrane anodic Fenton treatment (AFT), a Fenton technology with application potential for on-site treatment of pesticide wastewater. It was found that the degradation kinetics of metribuzin do not obey the AFT model, a previously developed model that fit AFT degradation kinetics of all previously investigated pesticides. The lack of fit for metribuzin data was determined to result from a weak interaction between metribuzin and the ferric ion, resulting in a significant reduction in availability of metribuzin for reaction with hydroxyl radicals during AFT, thus slowing degradation. A revised kinetic model was developed based on the original AFT model with the addition of this interaction. Results demonstrate that the new kinetic model fits metribuzin degradation data quite well at different delivery rates of Fenton reagent and at different temperatures. This weak interaction is also found to exist between ferric ion and several other triazinone/triazine herbicides during membrane AFT. The interaction intensity correlates with the electron-withdrawing/-donating property of substituents on the triazine/triazinone ring. The stronger the electron-donating ability of substituents, the stronger the interaction. PMID:14998041

Wang, Qiquan; Scherer, Emily M; Lemley, Ann T

2004-02-15

416

Human exposure to ferric sulfate aerosol: effects on pulmonary function and respiratory symptoms  

SciTech Connect

Twenty normal and 18 asthmatic human volunteers were exposed to ferric sulfate aerosol at a nominal concentration of 75 ..mu..g/m/sup 3/ (equivalent to 20 ..mu..g iron/m/sup 3/). The concentration and particle size distribution were selected to simulate worst case ambient conditions. A double-blind protocol was followed in which each subject was exposed on two days, separated by about a three week period. The subjects were exposed to clean air (sham) on one day and to ferric sulfate aerosol on the other (exposure); the order of exposure was selected randomly. Pulmonary function tests were performed immediately before (pre) and after (post) each 2 h sham or exposure period; this protocol included intermittent excercise. On the average, the two groups of subjects did not exhibit significant pre- to post-changes in total respiratory system resistance, forced expiratory flow/volume performance, and single breath nitrogen washout parameters. None of the subjects reported more than slight changes in symptoms during exposure.

Kleinman, M.T.; Linn, W.S.; Bailey,, R.M.; Anderson, K.R.; Whynot, J.D.; Medway, D.A.; Hackney, J.D.

1981-04-01

417

Synovectomy of the rheumatoid knee using intra-articular injection of dysprosium-165-ferric hydroxide macroaggregates  

SciTech Connect

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.

Sledge, C.B.; Zuckerman, J.D.; Shortkroff, S.; Zalutsky, M.R.; Venkatesan, P.; Snyder, M.A.; Barrett, W.P.

1987-09-01

418

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

SciTech Connect

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.

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

419

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 ...

420

Identification and Characterization of a Novel-type Ferric Siderophore Reductase from a Gram-positive Extremophile*  

PubMed Central

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.

Miethke, Marcus; Pierik, Antonio J.; Peuckert, Florian; Seubert, Andreas; Marahiel, Mohamed A.

2011-01-01

421

Identification and characterization of a novel-type ferric siderophore reductase from a gram-positive extremophile.  

PubMed

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 K(i) values in the micromolar range. The principal catalytic mechanism was found to couple increasing K(m) and K(D) values of substrate binding with increasing k(cat) 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

Miethke, Marcus; Pierik, Antonio J; Peuckert, Florian; Seubert, Andreas; Marahiel, Mohamed A

2010-11-04

422

Meta-analysis of efficacy and safety of intravenous ferric carboxymaltose (Ferinject) from clinical trial reports and published trial data  

PubMed Central

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.

2011-01-01

423

A comparison of various ion exchange resins for the removal of ferric ions from copper electrowinning electrolyte solutions Part II: Electrolytes containing antimony and bismuth  

Microsoft Academic Search

Four commercially available ion exchange resins were tested to compare their ability to remove ferric from copper electrowinning electrolytes containing antimony and bismuth. Ion exchange batch tests were performed in the initial phase of the study and indicated that all resins tested co-loaded some antimony with the ferric. The aminophosphonic resin tested was the only resin to load a significant

Bethan McKevitt; David Dreisinger

2009-01-01

424

Experimental investigation of the effect of oxygen fugacity on ferric-ferrous ratios and unit-cell parameters of four natural clinoamphiboles  

Microsoft Academic Search

but the results suggest that other mechanisms may also be involved. All four amphiboles exhibited systematically higher ferric-ferrous ratios with increasing 6, of equilibration. Equilibrium R values were achieved relatively rapidly and could be readily restored to onginal values by treatment at the appropriate buffer. In some cases, a metastable equi- librium of ferric-ferrous ratio was achieved before the amphibole

A. Cr-own; Ronnnr K. Popp