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1

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

2

High Resolution Transmission Electron Microscopy (HRTEM) of Nanophase Ferric Oxides.  

National Technical Information Service (NTIS)

Iron oxide minerals are the prime candidates for Fe(III) signatures in remotely sensed Martian surface spectra. Magnetic, Mossbauer, and reflectance spectroscopy have been carried out in the laboratory in order to understand the mineralogical nature of Ma...

D. C. Golden R. V. Morris D. W. Ming H. V. Lauer

1994-01-01

3

21 CFR 186.1300 - Ferric oxide.  

Code of Federal Regulations, 2010 CFR

...186.1300 Ferric oxide. (a) Ferric oxide (iron (III) oxide, Fe2 O3 , CAS Reg. No. 1309-37-1...It may be prepared synthetically by heating brown iron hydroxide oxide. The product is red-brown to black trigonal...

2009-04-01

4

21 CFR 186.1300 - Ferric oxide.  

Code of Federal Regulations, 2013 CFR

...186.1300 Ferric oxide. (a) Ferric oxide (iron (III) oxide, Fe2 O3 , CAS Reg. No. 1309-37-1...It may be prepared synthetically by heating brown iron hydroxide oxide. The product is red-brown to black trigonal...

2013-04-01

5

21 CFR 186.1300 - Ferric oxide.  

Code of Federal Regulations, 2010 CFR

...186.1300 Ferric oxide. (a) Ferric oxide (iron (III) oxide, Fe2 O3 , CAS Reg. No. 1309-37-1...It may be prepared synthetically by heating brown iron hydroxide oxide. The product is red-brown to black trigonal...

2010-01-01

6

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

7

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

8

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

9

NMR study of nanophase Al/Al-oxide powder and consolidated composites  

SciTech Connect

{sup 27}Al Nuclear Magnetic Resonance (NMR) measurements from aluminum powders and consolidated nanophase aluminum made from those powders are presented. The signals from the metal and surface oxidation are easily separated and are compared before and after consolidation. The results presented indicate that the oxide coating becomes the interface region within the nanophase composite material and that during consolidation the metal has undergone a deformation equivalent to that seen for bulk material under a compressive strain of between 4% and 8%.

Suits, B.H.; Apte, P.; Wilken, D.E. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Physics; Siegel, R.W. [Argonne National Lab., IL (United States). Materials Science Div.

1994-10-01

10

Modified electrochromism of tungsten oxide via platinum nanophases  

Microsoft Academic Search

We report electrochromic properties of WO3 modified by platinum nanophases. The WO3 incorporated by Pt metallic nanophases (Pt-WO3) showed exactly reverse electrochromic phenomenon compared with that of both pure WO3 and WO3 intercepted and coated by metallic Pt thin-film layer. In addition, to investigate the origin of modified electrochromic properties, electrodes consisting of WO3 and\\/or Pt layers were designed and

Kyung-Won Park; Hee-Sang Shim; Tae-Yeon Seong; Yung-Eun Sung

2006-01-01

11

D2-m-Carborane-Siloxanes. VI. Oxidative Stabilization of Vulcanizates with Ferric Oxide.  

National Technical Information Service (NTIS)

Ferric oxide produced from iron pentacarbonyl was evaluated as an oxidative stabilizer in D2-m-carborane-siloxane and polydimethylsiloxane vulcanizates. The results indicate a significant improvement in efficiency compared to powdered ferric oxide. Thus a...

E. N. Peters D. D. Stewart J. J. Bohan D. W. McNeil

1977-01-01

12

Reactive nanophase oxide additions to melt-processed high-{Tc} superconductors  

SciTech Connect

Nanophase TiO{sub 2} and Al{sub 2}O{sub 3} powders were synthesized by a vapor-phase process and mechanically mixed with stoichiometric YBa{sub 2}Cu{sub 3}O{sub x} and TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} powders in 20 mole % concentrations. Pellets produced from powders with and without nanophase oxides were heated in air or O{sub 2} above the peritectic melt temperature and slow-cooled. At 4.2 K, the intragranular critical current density (J{sub c}) increased dramatically with the oxide additions. At 35--50 K, effects of the oxide additions were positive, but less pronounced. At 77 K, the additions decreased J{sub c}, probably because of inducing a depresion of the transition temperature.

Goretta, K.C.; Brandel, B.P.; Lanagan, M.T.; Hu, J.; Miller, D.J.; Sengupta, S. [Argonne National Lab., IL (United States); Parker, J.C.; Ali, M.N. [Nanophase Technologies Corp., Darien, IL (United States); Chen, Nan [Illinois Superconductor Corp., Evanston, IL (United States)

1994-10-01

13

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

14

What ferric oxide/oxyhydroxide phases are present on Mars  

NASA Technical Reports Server (NTRS)

The weathering history of Mars can be deduced largely from the mineralogy and distribution of ferric oxide/oxyhydroxide phases. As discussed, some insights can be gained through spectrophotometric remote sensing, but absolute determinations must depend on direct laboratory analysis of returned Martian samples.

Morris, Richard V.

1988-01-01

15

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

PubMed

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

Birkner, Nancy; Navrotsky, Alexandra

2014-04-29

16

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

SciTech Connect

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

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

2013-02-15

17

Formation of ferric oxides from aqueous solutions: A polyhedral approach by X-ray absorption spectroscdpy: I. Hydrolysis and formation of ferric gels  

Microsoft Academic Search

X-ray absorption spectroscopy (XAS) was used to follow the evolution of local structural environments around ferric ions during the formation of ferric hydrous oxide gels from 1 M chloride and 0.1 M nitrate solutions. Fe K-XANES and EXAFS confirm that ferric ions remain 6-fold coordinated during this evolution. EXAFS spectra obtained on partially hydrolyzed ferric chloride solutions indicate the presence

J. M. Combes; A. Manceau; G. Calas; J. Y. Bottero

1989-01-01

18

Leaching of Bornite with Oxygen and Ferric Chloride as Oxidants.  

National Technical Information Service (NTIS)

Natural bornite (Cu5FeS4) leached in ferric chloride or in sulfuric or hydrochloric acid solutions with oxygen showed several differences. In ferric chloride 80% of the copper was leached in two stages. The first was controlled by liquid ferric ion diffus...

F. A. Olson

1982-01-01

19

Existence of a hydrogen sulfide: Ferric ion oxidoreductase in iron-oxidizing bacteria  

Microsoft Academic Search

The existence of a hydrogen sulfide:ferric ion oxidoreductase, which catalyzes the oxidation of elemental sulfur with ferric ions as an electron acceptor to produce ferrous and sulfite ions, was assayed with washed intact cells and cell extracts of various kinds of iron-oxidizing bacteria, such as Thiobacillus ferrooxidans 13598, 13661, 14119, 19859, 21834, 23270, and 33020 from the American Type Culture

Tsuyoshi Sugio; K. J. White; E. Shute; D. Choate; R. C. Blake

1992-01-01

20

Graphene oxide\\/ferric hydroxide composites for efficient arsenate removal from drinking water  

Microsoft Academic Search

A series of novel composites based on graphene oxide (GO) cross-linked with ferric hydroxide was developed for effective removal of arsenate from contaminated drinking water. GO, which was used as a supporting matrix here, was firstly treated with ferrous sulfate. Then, the ferrous compound cross-linked with GO was in situ oxidized to ferric compound by hydrogen peroxide, followed by treating

Kai Zhang; Vineet Dwivedi; Chunyan Chi; Jishan Wu

2010-01-01

21

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

22

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

2013-09-10

23

Formation of ferric oxides from aqueous solutions: A polyhedral approach by X-ray absorption spectroscopy. I. Hydrolysis and formation of ferric gels  

Microsoft Academic Search

X-ray absorption spectroscopy (XAS) was used to follow the evolution of local structural environments around ferric ions during the formation of ferric hydrous oxide gels from 1 M chloride and 0.1 M nitrate solutions. Fe K-XANES and EXAFS confirm that ferric ions remain 6-fold coordinated during this evolution. With increasing OH availability in the solution, Cl⁻ anions tend gradually to

J. M. Combes; A. Manceau; G. Calas; J. Y. Bottero

1989-01-01

24

Ferric iron reduction by sulfur- and iron-oxidizing bacteria. [Clostridium and Methanobacterium  

Microsoft Academic Search

Acidophilic bacteria of the genera Thiobacillus and Sulfolobus are able to reduce ferric iron when growing on elemental sulfur as an energy source. It has been previously thought that ferric iron serves as a nonbiological oxidant in the formation of acid mine drainage and in the leaching of ores, but these results suggest that bacterial catalysis may play a significant

T. D. Brock; J. Gustafson

1976-01-01

25

Ferric hydrogensulfate catalyzed aerobic oxidative coupling of 2-naphthols in water or under solvent free conditions  

Microsoft Academic Search

The symmetric oxidative coupling reactions of 2-naphthol derivatives with both ferric hydrogensulfate in water and silica ferric hydrogensulfate in solvent free conditions were carried out. The advantages of this green procedure are: inexpensive catalyst or co-catalyst, reusability of catalyst, organic solvent-free procedures and simple workup.

Hossein Eshghi; Mehdi Bakavoli; Hassanali Moradi

2009-01-01

26

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

2013-03-19

27

Dietary bioavailability of Cu adsorbed to colloidal hydrous ferric oxide  

USGS Publications Warehouse

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

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

2013-01-01

28

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

EPA Science Inventory

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

29

Optimal conditions for bio-oxidation of ferrous ions to ferric ions using Thiobacillus ferrooxidans  

Microsoft Academic Search

A chemo-biochemical process using Thiobacillus ferrooxidans for desulphurization of gaseous fuels and emissions containing hydrogen sulphide (H2S) has been developed. In the first stage, H2S present in fuel gas and emissions is selectively oxidized to elemental sulphur using ferric sulphate. The ferrous sulphate produced in the first stage of the process is oxidized to ferric sulphate using Thiobacillus ferrooxidans for

S. Malhotra; A. S. Tankhiwale; A. S. Rayvaidya; R. A. Pandey

2002-01-01

30

Urinary Excretion of Biomarkers of Oxidative Kidney Damage Induced by Ferric Nitrilotriacetate  

Microsoft Academic Search

There is an increasing need for biomarkers of oxidative stress in animals and man. In this study, we have evaluated in the rat the utility of various endogenous products that are excreted in urine as potential noninvasive biomarkers of oxidative stress in the kidney. Renal oxidative damage was induced by daily ip injections of ferric nitrilotriacetate (Fe-NTA) for a period

R. C. A. Hermanns; L. L. de Zwart; P. J. M. Salemink; J. N. M. Commandeur; N. P. E. Vermeulen; J. H. N. Meerman

1998-01-01

31

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

32

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

33

Generation of ferric Lixiviant by bio?oxidation of pyrite for in?situ leaching  

Microsoft Academic Search

Acidic ferric ion, an effective and important oxidizing agent for mineral leaching, is usually produced by direct dissolution of the corresponding salts into the solution or can be prepared in?situ or in separate aerated batch reactors by chemical oxidation of iron sulfide through a number of different processes. The purpose of this paper is to present the idea and the

1984-01-01

34

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

EPA Science Inventory

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

35

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

36

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

PubMed Central

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

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

2013-01-01

37

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

2013-05-28

38

The formation of magnetic ferric oxides in soils over underground gas storage reservoirs  

NASA Astrophysics Data System (ADS)

The concepts of the specific mechanisms responsible for the formation of magnetic ferric oxides in soils over artificial gas storage reservoirs are considered for the first time. Upon the interaction of technogenic allochthonous methane with soil, some biogeochemical barriers are formed that are characterized by the accumulation of solid products resulting from the functioning and development of the soil. The pedogenic new formations are represented by fine magnetic ferric oxides of specific shape. They are the result of an elementary soil-forming process—oxidogenesis composed of a complex of microprocesses of biogenic and abiogenic nature.

Mozharova, N. V.; Pronina, V. V.; Ivanov, A. V.; Shoba, S. A.; Zagurskii, A. M.

2007-06-01

39

21 CFR 184.1307 - Ferric sulfate.  

Code of Federal Regulations, 2010 CFR

...Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2 (SO4 )3 ...substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The...

2009-04-01

40

21 CFR 184.1307 - Ferric sulfate.  

Code of Federal Regulations, 2013 CFR

...Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2 (SO4 )3 ...substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The...

2013-04-01

41

21 CFR 184.1307 - Ferric sulfate.  

Code of Federal Regulations, 2010 CFR

...Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2 (SO4 )3 ...substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The...

2010-01-01

42

Effects of ferric oxide on decompositions of methyl ethyl ketone peroxide  

Microsoft Academic Search

Methyl ethyl ketone peroxide (MEKPO) is a widely used initiator for polymerization reaction and hardener in glass-reinforced plastic. However, MEKPO is an unstable reactive chemical and has caused several serious accidents all over the world. This work studied the thermal stability of MEKPO in the presence of ferric oxide as the contaminant through calorimetric and kinetic studies. The calorimetry was performed

Wei Meng; Yuan Lu; Victor H. Carreto-Vazquez; Qingsheng Wang; M. Sam Mannan

43

Extracting indium and preparing ferric oxide for soft magnetic ferrite materials from zinc calcine reduction lixivium  

Microsoft Academic Search

A hydrometallurgical process for indium extraction and ferric oxide powder preparation for soft magnetic ferrite material\\u000a was developed. Using reduction lixivium from high-acid reductive leaching of zinc oxide calcine as raw solution, copper and\\u000a indium were firstly recovered by iron powder cementation and neutralization. The recovery ratios of Cu and In are 99% and\\u000a 95%, respectively. Some harmful impurities that

Jing He; Mo-tang Tang; Cun Zhou; Sheng-nan Wu; Yong-ming Chen; Tao Wang; Ling Huang

2011-01-01

44

Shock ignition of pyrotechnic heat powders. [Aluminium/ferric oxide mixture  

SciTech Connect

Over a dozen pyrotechnic mixtures of alloy forming elements or solid oxidizers and fuels were subjected to shock pressures of from 2 to 35 GPa. More than half of these formulations were ignited by the shock. Visible and ir time resolved radiometry experiments using one of these mixtures, aluminum/ferric oxide, showed that this shock induced ignition occurred in less than 0.1 usec. 9 refs., 15 figs., 3 tabs.

Hornig, H.C.; Kury, J.W.; Simpson, R.L.; Helm, F.H.; Von Holle, W.G.

1986-05-14

45

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

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

1987-01-01

46

Formation of ferric oxides from aqueous solutions: A polyhedral approach by X-ray absorption spectroscopy. I. Hydrolysis and formation of ferric gels  

SciTech Connect

X-ray absorption spectroscopy (XAS) was used to follow the evolution of local structural environments around ferric ions during the formation of ferric hydrous oxide gels from 1 M chloride and 0.1 M nitrate solutions. Fe K-XANES and EXAFS confirm that ferric ions remain 6-fold coordinated during this evolution. With increasing OH availability in the solution, Cl{sup {minus}} anions tend gradually to be exchanged for (O, OH, OH{sub 2}) ligands. Below OH/Fe = 1, no structural order is detected beyond the first coordination sphere. Above this ratio, two Fe-Fe distances at 3.05 {angstrom} and 3.44 {angstrom} are observed and correspond to the presence of edge- and vertex-sharing Fe-octahedra. XAS results show that ferric gels and highly polymerized aqueous species are short-range ordered. The main contribution to disorder in the gels arises from the small size of coherently scattering domains also responsible for their X-ray amorphous character. From the initial to the final stage of hydrolysis, particles possess a nearly spherical shape with a minimum average diameter ranging from 10-30 {angstrom} for polymers formed from chloride and nitrate solutions. As polymerization proceeds, the local order extends to several tens of angstroms and the particle structures becomes progressively closer to that of akaganeite ({beta}-FeOOH) or goethite ({alpha}-FeOOH). This local structure is distinct from that of the lepidocrocite ({gamma}-FeOOH)-like structure of ferric gels precipitated after oxidation of divalent Fe solutions. The growth of the crystalline Fe-oxyhydroxides from gels takes place by the progressive long-range ordering in the ferric polymers without modifying the short-range order around Fe.

Combes, J.M.; Manceau, A.; Calas, G. (Universites Paris (France)); Bottero, J.Y. (Centre de Recherche sur la Valorisation des Minerais, Vandoeuvre (France))

1989-03-01

47

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

48

Formation of ferric oxides from aqueous solutions: A polyhedral approach by X-ray absorption spectroscdpy: I. Hydrolysis and formation of ferric gels  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy (XAS) was used to follow the evolution of local structural environments around ferric ions during the formation of ferric hydrous oxide gels from 1 M chloride and 0.1 M nitrate solutions. Fe K-XANES and EXAFS confirm that ferric ions remain 6-fold coordinated during this evolution. EXAFS spectra obtained on partially hydrolyzed ferric chloride solutions indicate the presence of aqua-chloro ferric complexes up to OH/Fe = 2.2. When OH/Fe < 1 in the solution, iron mainly occurs in trans-[ FeCl2( H2O) 4] 2+ octahedra with Fe-Cl and Fe-O distances of 2.31 and 2.01 Å, respectively. With increasing OH availability in the solution, Cl - anions tend gradually to be exchanged for (O,OH,OH 2) ligands. Below OH/Fe = 1, no structural order is detected beyond the first coordination sphere. Above this ratio, two Fe-Fe distances at 3.05 Å and 3.44 Å are observed and correspond to the presence of edge- and vertex-sharing Fe-octahedra. XAS results show that ferric gels and highly polymerized aqueous species are short-range ordered. The main contribution to disorder in the gels arises from the small size of coherently scattering domains also responsible for their X-ray 'amorphous' character. From the initial to the final stage of hydrolysis, particles possess a nearly spherical shape with a minimum average diameter ranging from 10-30 Å for polymers formed from chloride and nitrate solutions. As polymerization proceeds, the local order extends to several tens of angströms and the particle structures becomes progressively closer to that of akaganeite (?-FeOOH) or goethite (?-FeOOH). This local structure is distinct from that of the lepidocrocite (?-FeOOH)-like structure of ferric gels precipitated after oxidation of divalent Fe solutions. The growth of the crystalline Fe-oxyhydroxides from gels takes place by the progressive long-range ordering in the ferric polymers without modifying the short-range order around Fe.

Combes, J. M.; Manceau, A.; Calas, G.; Bottero, J. Y.

1989-03-01

49

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

50

Fibrogenic Potential of Intratracheally Instilled Quartz, Ferric Oxide, Fibrous Glass, and Hydrated Alumina in Hamsters  

Microsoft Academic Search

ABSTRAC~ As a first step in the development of an animal model for determining the role of pulmonary fibrosis in the etiology and pathogenesis of lung cancer, the fibrogenic potential of quartz, quartz and ferric oxide adm'inistered together, fibrous glass, and hydrated alumina were studied by multiple intratracheal instillation in groups of male 1ak:LVG Syrian golden hamsters. Dose-related decreases in

ROGER A. RENNE; SANDRA R. ELDRIDGE; TRENT R. LEWIS; DONALD L. STEVENS

1985-01-01

51

Nanoporous ferric oxide prepared with activated carbon template in supercritical carbon dioxide  

Microsoft Academic Search

Nanoporous ferric oxide has been prepared with nanoscale casting process using activated carbon template in supercritical carbon dioxide. The precursors with the cosolvent of acetone were dissolved in supercritical CO2, and then attached to activated carbon in the supercritical condition. After removal of the activated carbon template by calcinations in air at 873K, the nanoporous Fe2O3 was obtained. Four factors

Haijuan Fan; Qun Xu; Yiqun Guo; Qi Peng; Zhenzhong Hou

2006-01-01

52

A New Reagent, Ferric (III) Nitrate Supported on Graphite, for Selective Oxidation of Alcohols under Heterogeneous Conditions  

Microsoft Academic Search

The selective and effective oxidation of alcohols into the corresponding aldehydes and ketones under heterogeneous conditions by way of a new reagent, ferric (III) nitrate supported on graphite, is described.

Feng Li; Li Li

2006-01-01

53

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

54

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

55

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

56

Nitrite reduction with hydrous ferric oxide and Fe(II): stoichiometry, rate, and mechanism.  

PubMed

Fe(II)/Fe(III) oxide is an important redox couple in environmental systems. Recent studies have revealed unique characteristics of Fe(II)/Fe(III) oxide and reactions with oxidizing or reducing agents. Nitrite was used as an oxidizing agent in this study in order to probe details of these reactions and hydrous ferric oxide (HFO) was used as the Fe(III) oxide phase. Abiotic nitrite reduction is a significant global producer of nitric oxide (a catalyst for production of tropospheric ozone) and nitrous oxide (a greenhouse gas and contributor to stratospheric ozone depletion). All experiments were conducted at pH 6.8 using a strictly anoxic environment with mass-balance measurements for Fe(II). Oxidation of Fe(II) was negligible in the absence of HFO. The reaction was fast in the presence of HFO and was described by d[Fe(II)]/dt=-k(overall)[Fe(II)(diss)][Fe(II)(solid-bound)][NO(2)(-)] (k(overall)=2.59x10(-7)microM(-2)min(-1)) for Fe(II)/Fe(III) molar ratios less than 0.30. The reaction was inhibited for higher Fe(II)/HFO ratios. The concentration of solid-bound Fe(II) was constant after an initial equilibration period and the reaction stopped when dissolved Fe(II) was depleted even though substantial solid-bound Fe(II) and nitrite remained. The results regarding rate-dependence and conservation of solid-bound Fe(II) and inhibition of reaction at high Fe(II)/Fe(III) ratios were similar to our earlier results for the Fe(II)/HFO/O(2) system [Park, B., Dempsey, B.A., 2005. Heterogeneous oxidation of Fe(II) on ferric oxide at neutral pH and a low partial pressure of O(2). Environmental Science and Technology 39(17), 6494-6500.]. PMID:19081595

Tai, Yuan-Liang; Dempsey, Brian A

2009-02-01

57

YREE sorption on hydrous ferric oxide in 0.5 M NaCl solutions: A model extension  

Microsoft Academic Search

Distribution coefficients, iKFe, were measured for sorption of yttrium and the rare earth elements (YREEs) on hydrous ferric oxide (HFO) in 0.5M NaCl solutions over the pH range 3.9–8.4 (T=25°C). An existing, non-electrostatic model [Quinn, K.A., Byrne, R.H., Schijf, J., 2006. Sorption of yttrium and rare earth elements by amorphous ferric hydroxide: influence of pH and ionic strength. Mar. Chem.

Johan Schijf; Kathleen S. Marshall

2011-01-01

58

Sorption of Ferric Iron from Ferrioxamine B to Synthetic and Biogenic Layer Type Manganese Oxides  

NASA Astrophysics Data System (ADS)

Siderophores are biogenic chelating agents produced in terrestrial and marine environments to increase the bioavailablity of ferric iron. Recent work has suggested that both aqueous and solid-phase Mn(III) may affect siderophore-mediated iron transport, but no information appears to be available about the effect of solid-phase Mn(IV). To probe the effects of predominantly Mn(IV) oxides, we studied the sorption reaction of ferrioxamine B [Fe(III)HDFOB+, an Fe(III) chelate of the trihydroxamate siderophore desferrioxamine B (DFOB)] with two synthetic birnessites [layer type Mn(III, IV) oxides] and a biogenic birnessite produced by Pseudomonas putida MnB1. We found that all of these predominantly Mn(IV) oxides greatly reduced the aqueous concentration of Fe(III)HDFOB+ over at pH 8. After 72 hours equilibration time, the sorption behavior for the synthetic birnessites could be accurately described by a Langmuir isotherm; for the biogenic oxide, a Freundlich isotherm was best utilized to model the sorption data. To study the molecular nature of the interaction between the Fe(III)HDFOB+ complex and the oxide surface, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy was employed. Analysis of the EXAFS spectra indicated that Fe(III) associated with the Mn(IV) oxides is not complexed by DFOB as in solution, but instead Fe(III) is specifically adsorbed to into the mineral structure at multiple sites with no evidence of DFOB complexation, thus indicating that the Mn(IV) oxides displaced Fe(III) from the siderophore complex. These results indicate that manganese oxides, including biominerals, may strongly sequester iron from soluble ferric complexes and thus may play a significant role in the biogeochemical cycling of iron in marine and terrestrial environments.

Duckworth, O.; John, B.; Sposito, G.

2006-12-01

59

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

NASA Technical Reports Server (NTRS)

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.

1992-01-01

60

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

61

A beverage containing fermented black soybean ameliorates ferric nitrilotriacetate-induced renal oxidative damage in rats.  

PubMed

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

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

2010-11-01

62

Effect of functional groups on the crystallization of ferric oxides/oxyhydroxides in suspension environment  

NASA Astrophysics Data System (ADS)

This paper investigated the effects of five kinds of Au surfaces terminated with and without functional groups on the crystallization of ferric oxides/oxyhydroxides in the suspension condition. Self-assembled monolayers (SAMs) were used to create hydroxyl (-OH), carboxyl (-COOH), amine (-NH2) and methyl (-CH3) functionalized surfaces, which proved to be of the same surface density. The immersion time of substrates in the Fe(OH)3 suspension was divided into two time portions. During the first period of 2 h, few ferric oxide/oxyhydroxide was deposited except that ?-Fe2O3 was detected on -NH2 surface. Crystallization for 10 h evidenced more kinds of iron compounds on the functional surfaces. Goethite and maghemite were noticed on four functional surfaces, and maghemite also grew on Au surface. Deposition of ?-Fe2O3 was found on -OH surface, while the growth of orthorhombic and hexagon FeOOH were indicated on -NH2 surface. Considering the wide existence of iron compounds in nature, our investigation is a precedent work to the study of iron biomineralization in the suspension area.

Zhou, Qiong; Albert, Olga; Deng, Hua; Yu, Xiao-Long; Cao, Yang; Li, Jian-Bao; Huang, Xin

2012-12-01

63

Radiation effects on the activity of ferric oxide catalysts for the decomposition of hydrogen peroxide  

NASA Astrophysics Data System (ADS)

The catalytic and some physico-chemical properties of a variety of ferric oxides have been studied. Most of the catalysts prepared consisted of hematite and magnetite. The specific catalytic activities of the samples were found to be very different and their values appeared not to be determined by the ratio of the hematite and the magnetite present in the sample. Heat treatment of the samples changed their catalytic efficiency. ?-Irradiation ( 60Co) of the catalysts with the dose of 1 MGy led to a lower catalytic activity, ?-irradiation ( 90Sr- 90Y) with a dose of 10 kGy enhanced their catalytic efficiency and a neutron-irradiation ( 252Cf) with the dose of 425 Gy generated positive or negative radiation catalytic effects. The observed changes in catalytic activity of the treated samples may be explained in terms of the principle of bivalent catalytic sites provided that the surface concentration of the Fe 2+-Fe 3+ sites determines the catalytic activity of the ferric oxide.

Mú?ka, V.; Mižík, P.

64

Defect Clustering and Nano-phase Structure Characterization of Multicomponent Rare Earth-Oxide-Doped Zirconia-Yttria Thermal Barrier Coatings  

NASA Technical Reports Server (NTRS)

Advanced thermal barrier coatings (TBCs) have been developed by incorporating multicomponent rare earth oxide dopants into zirconia-based thermal barrier coatings to promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nanophases within the coating systems. In this paper, the defect clusters, induced by Nd, Gd, and Yb rare earth dopants in the zirconia-yttria thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The TEM lattice imaging, selected area diffraction (SAD), and electron energy-loss spectroscopy (EELS) analyses demonstrated that the extensive nanoscale rare earth dopant segregation exists in the plasma-sprayed and electron-physical-vapor-deposited (EB PVD) thermal barrier coatings. The nanoscale concentration heterogeneity and the resulting large lattice distortion promoted the formation of parallel and rotational defective lattice clusters in the coating systems. The presence of the 5-to 100-nm-sized defect clusters and nanophases is believed to be responsible for the significant reduction of thermal conductivity, improved sintering resistance, and long-term high temperature stability of the advanced thermal barrier coating systems.

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

2004-01-01

65

Hydrous ferric oxide precipitation in the presence of nonmetabolizing bacteria: Constraints on the mechanism of a biotic effect  

NASA Astrophysics Data System (ADS)

We have used room temperature and cryogenic 57Fe Mössbauer spectroscopy, powder X-ray diffraction (pXRD), mineral magnetometry, and transmission electron microscopy (TEM), to study the synthetic precipitation of hydrous ferric oxides (HFOs) prepared either in the absence (abiotic, a-HFO) or presence (biotic, b-HFO) of nonmetabolizing bacterial cells ( Bacillus subtilis or Bacillus licheniformis, ˜10 8 cells/mL) and under otherwise identical chemical conditions, starting from Fe(II) (10 -2, 10 -3, or 10 -4 mol/L) under open oxic conditions and at different pH (6-9). We have also performed the first Mössbauer spectroscopy measurements of bacterial cell wall ( Bacillus subtilis) surface complexed Fe, where Fe(III) (10 -3.5-10 -4.5 mol/L) was added to a fixed concentration of cells (˜10 8 cells/mL) under open oxic conditions and at various pH (2.5-4.3). We find that non-metabolic bacterial cell wall surface complexation of Fe is not passive in that it affects Fe speciation in at least two ways: (1) it can reduce Fe(III) to sorbed-Fe 2+ by a proposed steric and charge transfer effect and (2) it stabilizes Fe(II) as sorbed-Fe 2+ against ambient oxidation. The cell wall sorption of Fe occurs in a manner that is not compatible with incorporation into the HFO structure (different coordination environment and stabilization of the ferrous state) and the cell wall-sorbed Fe is not chemically bonded to the HFO particle when they coexist (the sorbed Fe is not magnetically polarized by the HFO particle in its magnetically ordered state). This invalidates the concept that sorption is the first step in a heterogeneous nucleation of HFO onto bacterial cell walls. Both the a-HFOs and the b-HFOs are predominantly varieties of ferrihydrite (Fh), often containing admixtures of nanophase lepidocrocite (nLp), yet they show significant abiotic/biotic differences: Biotic Fh has less intraparticle (including surface region) atomic order (Mössbauer quadrupole splitting), smaller primary particle size (magnetometry blocking temperature), weaker Fe to particle bond strength (Mössbauer center shift), and no six-line Fh (6L-Fh) admixture (pXRD, magnetometry). Contrary to current belief, we find that 6L-Fh appears to be precipitated directly, under a-HFO conditions, from either Fe(II) or Fe(III), and depending on Fe concentration and pH, whereas the presence of bacteria disables all such 6L-Fh precipitation and produces two-line Fh (2L-Fh)-like biotic coprecipitates. Given the nature of the differences between a-HFO and b-HFO and their synthesis condition dependences, several biotic precipitation mechanisms (template effect, near-cell environment effect, catalyzed nucleation and/or growth effect, and substrate-based coprecipitation) are ruled out. The prevailing present view of a template or heterogeneous nucleation barrier reduction effect, in particular, is shown not to be the cause of the large observed biotic effects on the resulting HFOs. The only proposed mechanism (relevant to Fh) that is consistent with all our observations is coprecipitation with and possible surface poisoning by ancillary bacteriagenic compounds. That bacterial cell wall functional groups are redox active and the characteristics of biotic (i.e., natural) HFOs compared to those of abiotic (i.e., synthetic) HFOs have several possible biogeochemical implications regarding Fe cycling, in the photic zones of water columns in particular.

Rancourt, Denis G.; Thibault, Pierre-Jean; Mavrocordatos, Denis; Lamarche, Gilles

2005-02-01

66

High k nanophase zinc oxide on biomimetic silicon nanotip array as supercapacitors.  

PubMed

A 3D trenched-structure metal-insulator-metal (MIM) nanocapacitor array with an ultrahigh equivalent planar capacitance (EPC) of ~300 ?F cm(-2) is demonstrated. Zinc oxide (ZnO) and aluminum oxide (Al2O3) bilayer dielectric is deposited on 1 ?m high biomimetic silicon nanotip (SiNT) substrate using the atomic layer deposition method. The large EPC is achieved by utilizing the large surface area of the densely packed SiNT (!5 × 10(10) cm(-2)) coated conformally with an ultrahigh dielectric constant of ZnO. The EPC value is 30 times higher than those previously reported in metal-insulator-metal or metal-insulator-semiconductor nanocapacitors using similar porosity dimensions of the support materials. PMID:23432577

Han, Hsieh-Cheng; Chong, Cheong-Wei; Wang, Sheng-Bo; Heh, Dawei; Tseng, Chi-Ang; Huang, Yi-Fan; Chattopadhyay, Surojit; Chen, Kuei-Hsien; Lin, Chi-Feng; Lee, Jiun-Haw; Chen, Li-Chyong

2013-04-10

67

Fluorescence turn-on detection of gaseous nitric oxide using ferric dithiocarbamate complex functionalized quantum dots.  

PubMed

Functional quantum dots (QDs) grafted with ferric dithiocarbamate complex layers (QDs-Fe(III)(DTC)3) were fabricated and demonstrated to be selectively reactive to nitric oxide. The dithiocarbamate (DTC) was covalently conjugated to the amine-coated QDs by a condensation reaction of the carboxyl in DTC and the amino polymer in surface of QDs. The weak fluorescence of QDs-Fe(III)(DTC)3 was attributed to the energy transfer between CdSe/ZnS and Fe(III)(DTC)3 complex at the surface of the functionalized quantum dots. Nitric oxide could greatly switch on the fluorescence of QDs-Fe(III)(DTC)3 by displacing the DTC in the Fe(III)(DTC)3 accompanied by reducing Fe(III) to Fe(II), thus shutting off the energy transfer way. The limit of detection for nitric oxide was estimated to be 3.3 ?M and the specific detection was not interfered with other reactive oxygen species. Moreover, the probe was demonstrated for the sensing of gaseous nitric oxide, and the visual detection limit was as low as 10 ppm, showing the potential for sensing nitric oxide by the naked eye. PMID:24893881

Sun, Jian; Yan, Yehan; Sun, Mingtai; Yu, Huan; Zhang, Kui; Huang, Dejian; Wang, Suhua

2014-06-17

68

Boat pressure washing wastewater treatment with calcium oxide and/or ferric chloride.  

PubMed

The aim of this study was to investigate the efficiency of (1) chemical precipitation by calcium oxide, (2) coagulation/flocculation by ferric chloride (FC), and (3) the combination these two methods in reducing the toxicity of wastewater generated by boat pressure washing. All three methods gave satisfactory results in the removal of colour, turbidity, Cr, Fe, Cu, Zn, and Pb. The concentrations of heavy metals were lowered below national limits with 1 g of CaO, 2.54 mg of Fe3+ in the form of FeCl3x6H2O, and the combination of 0.25 g of CaO and 5.08 mg of Fe3+ per 50 mL of wastewater. Both CaO (1.50 g per 50 mL of wastewater) and FC proved efficient, but their combination yielded a significantly better performance: 99.41 %, 100.00 %, 97.87 %, 99.09 %, 99.90 %, 99.46 % and 98.33 % for colour, turbidity, Cr, Fe, Cu, Zn, and Pb respectively. For colour, Cr, Cu, Zn, and Pb removal efficiencies increased in the following order: FCoxide followed by ferric chloride is efficient, cost-effective, and user-friendly. PMID:22450202

Oreš?anin, Višnja; Kollar, Robert; Na?, Karlo; Mikeli?, Ivanka Lovren?i?; Mikuli?, Nenad

2012-03-01

69

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

Microsoft Academic Search

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

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

2009-01-01

70

Growth mechanisms of iron oxide particles of differing morphologies from the forced hydrolysis of ferric chloride solutions  

Microsoft Academic Search

To determine the growth mechanisms responsible for the different morphologies, the authors used time resolved transmission electron microscopy to follow the growth of iron oxide particles produced by the forced hydrolysis of ferric chloride solutions. The growth of three different hematite particle morphologies were investigated: cubes, spheres, and so-called double ellipsoids. The morphology of the particles depends on the concentration

J. K. Bailey; C. J. Brinker; M. L. MeCartney

1993-01-01

71

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

72

Structure and stability of Cd[sup 2+] surface complexes on ferric oxides; 1: Results from EXAFS spectroscopy  

Microsoft Academic Search

In the environment, such different processes as transport and availability of contaminants in soils, scavenging and release of trace elements in water cycles, wastewater treatment, and groundwater protection are intimately correlated with interfacial chemical reactions. Extended X-ray absorption fine structure (EXAFS) spectroscopy has been used to study the adsorption and coprecipitation mechanism of Cd(II) on hydrous ferric oxide (HFO) and

L. Spadini; A. Manceau; L. Charlet; P. W. Schindler

1994-01-01

73

Preloading hydrous ferric oxide into granular activated carbon for arsenic removal.  

PubMed

Arsenic is of concern in water treatment because of its health effects. This research focused on incorporating hydrous ferric oxide (HFO) into granular activated carbon (GAC) for the purpose of arsenic removal. Iron was incorporated into GAC via incipient wetness impregnation and cured at temperatures ranging from 60 to 90 degrees C. X-ray diffractions and arsenic sorption as a function of pH were conducted to investigate the effect of temperature on final iron oxide (hydroxide) and their arsenic removal capabilities. Results revealed that when curing at 60 degrees C, the procedure successfully created HFO in the pores of GAC, whereas at temperatures of 80 and 90 degrees C, the impregnated iron oxide manifested a more crystalline form. In the column tests using synthetic water, the HFO-loaded GAC prepared at 60 degrees C also showed higher sorption capacities than media cured at higher temperatures. These results indicated that the adsorption capacity for arsenic was closely related to the form of iron (hydr)oxide for a given iron content For the column test using a natural groundwater, HFO-loaded GAC (Fe, 11.7%) showed an arsenic sorption capacity of 26 mg As/g when the influent contained 300 microg/L As. Thus, the preloading of HFO into a stable GAC media offered the opportunity to employ fixed carbon bed reactors in water treatment plants or point-of-use filters for arsenic removal. PMID:18522120

Jang, Min; Chen, Weifang; Cannon, Fred S

2008-05-01

74

Bovine lactoferrin ameliorates ferric nitrilotriacetate-induced renal oxidative damage in rats  

PubMed Central

Milk provides a well-balanced source of amino acids and other ingredients. One of the functional ingredients in milk is lactoferrin (LF). LF presents a wide variety of bioactivities and functions as a radical scavenger in models using iron-ascorbate complexes and asbestos. Human clinical trials of oral LF administration for the prevention of colon polyps have been successful and demonstrated that dietary compounds exhibit direct interactions. However, antioxidative properties of LF in distant organs require further investigation. To study the antioxidant property of LF, we employed bovine lactoferrin (bLF) using the rat model of ferric nitrilotriacetate (Fe-NTA)-induced renal tubular oxidative injury. We fed rats with bLF (0.05%, w/w) in basal chow for 4 weeks and sacrificed them after Fe-NTA treatment. After intraperitoneal administration of 9.0 mg iron/kg Fe-NTA for 4 and 24 h, bLF pretreatment suppressed elevation of serum creatinine and blood urea nitrogen levels. In addition, we observed protective effects against renal oxidative tubular damage and maintenance of antioxidant enzyme activities in the bLF-pretreated group. We thus demonstrated the antioxidative effect of bLF against Fe-NTA-induced renal oxidative injury. These results suggest that LF intake is useful for the prevention of renal tubular oxidative damage mediated by iron.

Okazaki, Yasumasa; Kono, Isato; Kuriki, Takayoshi; Funahashi, Satomi; Fushimi, Soichiro; Iqbal, Mohammad; Okada, Shigeru; Toyokuni, Shinya

2012-01-01

75

Occurrence of Surface Polysulfides during the Interaction between Ferric (Hydr)Oxides and Aqueous Sulfide.  

PubMed

Polysulfides are often referred to as key reactants in the sulfur cycle, especially during the interaction of ferric (hydr)oxides and sulfide, forming ferrous-sulphide minerals. Despite their potential relevance, the extent of polysulfide formation and its relevance for product formation pathways remains enigmatic. We applied cryogenic X-ray Photoelectron Spectroscopy and wet chemical analysis to study sulfur oxidation products during the reaction of goethite and lepidocrocite with aqueous sulfide at different initial Fe/S molar ratios under anoxic conditions at neutral pH. The higher reactivity of lepidocrocite leads to faster and higher electron turnover compared to goethite. We were able to demonstrate for the first time the occurrence of surface-associated polysulfides being the main oxidation products in the presence of both minerals, with a predominance of disulfide (S2(2-)(surf)), and elemental sulfur. Concentrations of aqueous polysulfide species were negligible (<1%). With prior sulfide fixation by zinc acetate, the surface-associated polysulfides could be precipitated as zerovalent sulfur (S°), which was extracted by methanol thereafter. Of the generated S°, 20-34% were associated with S2(2-)(surf). Varying the Fe/S ratio revealed that surface polysulfide formation only becomes dominant when the remaining aqueous sulfide concentration is low (<0.03 mmol L(-1)). We hypothesize these novel surface sulfur species, particularly surface disulfide, to act as pyrite precursors. We further propose that these species play an overlooked role in the sulfur cycle. PMID:24735157

Wan, Moli; Shchukarev, Andrey; Lohmayer, Regina; Planer-Friedrich, Britta; Peiffer, Stefan

2014-05-01

76

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

77

Sorption of Sr and U[VI] on Natural Mixtures of Hydrous Ferric and Aluminum Oxides  

NASA Astrophysics Data System (ADS)

Evaluating and predicting vadose and groundwater reactive transport at field-scales requires an understanding of the abundance and nature of sorptive materials along subsurface flow paths. As part of our ongoing research focused on evaluating in situ reactive surface area, we have investigated the sorption of Sr and U[VI] using batch experiments and sands coated with naturally occurring mixtures of hydrous ferric and aluminum oxides over a range of environmentally relevant pH and sorbate concentrations. The goal of our research is to develop field applicable methodologies for predicting reactive transport in variably saturated media of radionuclide contaminants (e.g., U[VI]) from the behavior of simple benign tracers (e.g., Sr). Our tracer approach represents an effective method to integrate abundant and inexpensive laboratory sorption measurements across multiple scales with field-scale tests and observations. Materials used in the study were sands naturally coated with hydrous ferric and aluminum oxides from a field site near Oyster, Virginia and had hydrous metal oxide contents that ranged from 1 to 70 ?mole g-1 and 8 to 50 ?mole g-1 for iron and aluminum, respectively. Surface areas ranged from 0.1 to 3.2 m2 g-1 and are closely correlated with the abundance of the hydrous metal oxide coatings. After accounting for variations in surface area, Sr sorption was linear, suggesting that it can be used as a surrogate for reactive surface area. The adsorption of U[VI] was more complex. Uranium adsorption can be described by the empirical relationship: Cs = K [Cl x A]n where Cs and Cl are the concentration of sorbed (mass/mass sand) and dissolved (mass/volume solution) uranium, respectively. A is the surface area (area/mass) of the sand, and K and n are the Freundlich constant and exponent, both of which exhibit pH dependency. The more complex sorption behavior of U is attributed to multiple sorption sites and changes in speciation as a function of pH. Preliminary results suggest that surface areas estimated from Sr sorption can be used to predict U sorption.

Smith, R. W.; Rosentreter, J. J.

2002-12-01

78

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

NASA Astrophysics Data System (ADS)

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

Ragavan, Anpalaki J.; Adams, Dean V.

2009-06-01

79

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

80

Synergistic Competitive Inhibition of Ferrous Iron Oxidation by Thiobacillus ferrooxidans by Increasing Concentrations of Ferric Iron and Cells  

PubMed Central

Oxidation of ferrous iron by Thiobacillus ferrooxidans SM-4 was inhibited competitively by increasing concentrations of ferric iron or cells. A kinetic analysis showed that binding of one inhibitor did not exclude binding of the other and led to synergistic inhibition by the two inhibitors. Binding of one inhibitor, however, was affected by the other inhibitor, and the apparent inhibition constant increased with increasing concentrations of the other inhibitor.

Lizama, Hector M.; Suzuki, Isamu

1989-01-01

81

The effects of a cocarcinogen, ferric oxide, on the metabolism of benzo[a]pyrene in the isolated perfused lung  

Microsoft Academic Search

An isolated perfused New Zealand rabbit lung preparation was used to investigate the effects of a cocarcinogen, ferric oxide (Fe2O3), 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. [C]?BaP was administered intratracheally to an isolated perfused lung (IPL) preparation with and

David Warshawsky; Eula Bingham; Richard W. Niemeier

1984-01-01

82

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

83

Retention of arsenic on hydrous ferric oxides generated by electrochemical peroxidation.  

PubMed

Electrochemical peroxidation (ECP), an emerging remediation technology, with direct electric current applied to steel electrode and small addition of H2O2, was used to remove As(III) from contaminated aqueous solutions. Bench scale experiments were conducted to evaluate the sorption and distribution of arsenic between the soluble and solid state hydrous ferric oxides (HFO) formed as part of the ECP process. ECP was effective in removing arsenic from the aqueous solution, with >98% of the applied As(III) adsorbed on HFO. Removal was complete within 3 min of ECP treatment and apparently independent of the initial pH of the water (3.5-9.5). In the absence of H2O2 more As(III) was adsorbed by solid state iron at pH 9.5 than at 3.5 (2600 vs. 1750 microg l(-1)). Thus H2O2 was crucial to oxidize As(III) to As(V) which is more strongly retained by HFO. Removal of As was not significantly affected by the concentration of H2O2 or by current processing time. The optimal operating conditions were pH < 6.5, H2O2 concentration of 10 mg l(-1) and current process time not exceeding 3 min. X-ray diffraction (XRD), diffuse-reflectance infrared Fourier transform (DRIFT) spectroscopy and transmission electron microscopy (TEM) were applied to study the HFO deposits. The XRD data indicated the prevalence of poorly ordered Fe minerals in the suspended ECP solids with a dominance of 5 line ferrihydrite in the absence of H2O2. At pH 3.5 and with 100 mg H2O2 l(-1), akaganeite was formed, whereas an incipient hematitic phase, reflection at 0.39 nm, occurred at pH 6.5. DRIFT data indicate that both As(III) and As(V) were specifically adsorbed onto HFO at acid and neutral pH. TEM observations indicated the presence of spherical shape ferrihydrite and provided evidence for possible formation of subrounded hematite and acicular shape goethite. PMID:12227505

Arienzo, Michele; Adamo, Paola; Chiarenzelli, Jeffrey; Bianco, Maria R; De Martino, Antonio

2002-09-01

84

Kinetic study of the oxidation of complex nickeliferous sulfide ore in aqueous ferric sulfate. [Pentlandite  

SciTech Connect

The kinetics of leaching the nickel, cobalt, and copper from the minerals pyrrhotite and pentlandite by ferric ion in a naturally occurring complex nickeliferous sulfide ore are presented. The kinetic results from these experiments can be represented in one equation with two unknowns (pyrrhotite and pentlandite minerals). Knowledge of the mineral-ferric ion reaction allows the separate determination of the leaching rates of nickel, cobalt, and copper from either the pyrrhotite or pentlandite mineral. This work has more practical significance in hydrometallurgical processing compared to data obtained using mixtures of pure nickel sulfide, cobalt sulfide, and copper sulfide.

Chang, Q.Z.; Bautista, R.G.

1984-01-01

85

Processing of nanophase ceramics  

SciTech Connect

The gas-condensation method for the production of small particles in the size range of 1 to 10 nm has recently enabled the synthesis of a new class of ultrafine-grained, nanophase ceramics. The first demonstrations of the synthesis of nanophase TiO/sub 2/ have shown that these ceramics, while already rather well bonded on compaction at room temperature, sinter rapidly above 500/sup 0/C, with only small increases in grain size, leading to Vickers hardness and fracture toughness values comparable to or greater than those of coarser-grained compacts, but at some 400 to 600/sup 0/C lower temperatures and without the need for sintering aids. 11 refs., 4 figs.

Hahn, H.; Eastman, J.A.; Siegel, R.W.

1987-11-01

86

Spectroscopic studies of the oxidation of ferric CYP153A6 by peracids: Insights into P450 higher oxidation states  

PubMed Central

Our previous rapid-scanning stopped-flow studies of the reaction of substrate-free cytochrome P450cam with peracids [T. Spolitak, J.H. Dawson, D.P. Ballou (2005) J. Biol. Chem. 280, 20300-20309; (2006) J. Inorg. Biochem. 100, 2034-2044; (2008) J. Biol. Inorg.Chem. 13, 599-611] spectrally characterized compound I (ferryl iron plus a porphyrin ?-cation radical (FeIV=O/Por •+)), Cpd ES, and Cpd II (FeIV=O/Tyr• or FeIV=O). We now report that reactions of CYP153A6 with peracids yield all these intermediates, with kinetic profiles allowing better resolution of all forms at pH 8.0 compared to similar reactions with WT P450cam. Properties of the reactions of these higher oxidation state intermediates were determined in double mixing experiments in which intermediates are pre-formed and ascorbate is then added. Reactions of heptane-bound CYP153A6 (pH 7.4) with mCPBA resulted in conversion of P450 to the low-spin ferric form, presumably as heptanol was formed, suggesting that CYP 153A6 is a potential biocatalyst that can use peracids with no added NAD(P)H or reducing systems for bioremediation and other industrial applications.

Spolitak, Tatyana; Funhoff, Enrico G.; Ballou, David P.

2009-01-01

87

Spectroscopic studies of the oxidation of ferric CYP153A6 by peracids: Insights into P450 higher oxidation states.  

PubMed

Our previous rapid-scanning stopped-flow studies of the reaction of substrate-free cytochrome P450cam with peracids [T. Spolitak, J.H. Dawson, D.P. Ballou, J. Biol. Chem. 280 (2005) 20300-20309; J. Inorg. Biochem. 100 (2006) 2034-2044; J. Biol. Inorg. Chem. 13 (2008) 599-611] spectrally characterized compound I (ferryl iron plus a porphyrin pi-cation radical (Fe(IV)O/Por(.+))), Cpd ES, and Cpd II (Fe(IV)O/Tyr() or Fe(IV)O). We now report that reactions of CYP153A6 with peracids yield all these intermediates, with kinetic profiles allowing better resolution of all forms at pH 8.0 compared to similar reactions with WT P450cam. Properties of the reactions of these higher oxidation state intermediates were determined in double-mixing experiments in which intermediates are pre-formed and ascorbate is then added. Reactions of heptane-bound CYP153A6 (pH 7.4) with mCPBA resulted in conversion of P450 to the low-spin ferric form, presumably as heptanol was formed, suggesting that CYP 153A6 is a potential biocatalyst that can use peracids with no added NAD(P)H or reducing systems for bioremediation and other industrial applications. PMID:19879854

Spolitak, Tatyana; Funhoff, Enrico G; Ballou, David P

2010-01-15

88

Synthesis of petal-like ferric oxide/cysteine architectures and their application in affinity separation of proteins.  

PubMed

Petal-like ferric oxide/cysteine (FeOOH/Cys) architectures were prepared through a solvothermal route, which possessed high thiol group density. These thiol groups as binding sites can chelate Ni(2+) ions, which can be further used to enrich and separate his-tagged proteins directly from the mixture of lysed cells without sample pretreatment. These results show that the FeOOH/Cys architectures with immobilized Ni(2+) ions present negligible nonspecific protein adsorption and high protein adsorption capacity, with the saturation capacity being 88mg/g, which are especially suitable for purification of his-tagged proteins. PMID:24268283

Zou, Xueyan; Li, Kun; Yin, Yanbin; Zhao, Yanbao; Zhang, Yu; Li, Binjie; Yao, Shasha; Song, Chunpeng

2014-01-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

90

Identification of ferric oxides in East Candor Chasma (Valles Marineris, Mars) with several methods of analysis of OMEGA/Mars Express data - geomorphological context  

NASA Astrophysics Data System (ADS)

The mineralogical composition of the Martian surface is constrained by analysing the data of the visible and near infrared imaging spectrometer OMEGA onboard Mars Express. We use three independent methods (Spectral Angle Mapper (Kruse et al., 1993), modified Linear Unmixing Model (Combe et al., 2006) and Modified Gaussian Model (Sunshine et al., 1990)) and we detect ferric oxides in East Candor Chasma. Ferric signatures had previously been reported in Valles Marineris, Margaritifer Terra and Terra Meridiani (Gendrin et al., 2005). Ferric oxides appear to be distributed in isolated areas in East Candor Chasma. MOLA altimetry indicates that the oxides are preferentially located in topographic lows (Christensen et al., 2001; Gendrin et al., 2005). THEMIS and MOC images show that the signatures are systematically correlated with superficial deposits of low albedo, at the foot or on Interior Layered Deposits (ILD's). Some sulfates have been identified on some of the ILD's of the region (Gendrin et al., 2005). The spatial distribution of ferric oxides in regard with ILD suggests that they are genetically linked. A remobilization of ferric oxides from the ILD's could explain their accumulation around the ILD's.

Le Deit, L.; Gendrin, A.; Le Mouelic, S.; Combe, J.-Ph.; Bourgeois, O.; Mege, D.; Sotin, C.; Hauber, E.; Bibring, J.-P.

91

Detecting Adsorbed Sulfate and Phosphate on Nanophase Weathering Products on Mars  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

92

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

93

Mechanical properties of nanophase materials  

SciTech Connect

It has become possible in recent years to synthesize new materials under controlled conditions with constituent structures on a nanometer size scale (below 100 nm). These novel nanophase materials have grain-size dependent mechanical properties significantly different than those of their coarser-grained counterparts. For example, nanophase metals are much stronger and apparently less ductile than conventional metals, while nanophase ceramics are more ductile and more easily formed than conventional ceramics. The observed mechanical property changes are related to grain size limitations and/or the large percentage of atoms in grain boundary environments; they can also be affected by such features as flaw populations, strains and impurity levels that can result from differing synthesis and processing methods. An overview of what is presently known about the mechanical properties of nanophase materials, including both metals and ceramics, is presented. Some possible atomic mechanisms responsible for the observed behavior in these materials are considered in light of their unique structures.

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

1993-11-01

94

Ferricyanide-mediated oxidation of ferrous nitrosylated sperm whale myoglobin involves the formation of the ferric nitrosylated intermediate.  

PubMed

Ferricyanide-mediated oxidation of ferrous oxygenated and carbonylated myoglobin (Mb(II)-O(2) and Mb(II)-CO, respectively) is limited by O(2) and CO dissociation, respectively, then the transient deoxygenated derivative (Mb(II)) is rapidly oxidized. Here, kinetics of ferricyanide-mediated oxidation of ferrous nitrosylated sperm whale myoblobin (Mb(II)-NO) is reported. Unlike for Mb(II)-O(2) and Mb(II)-CO, ferricyanide reacts with Mb(II)-NO forming first a transient ferric nitrosylated species (Mb(III)-NO), followed by the ()NO dissociation from Mb(III)-NO. Values of the second-order rate constant for ferricyanide-mediated oxidation of Mb(II)-NO (i.e., for the formation of the transient Mb(III)-NO species) and of the first-order rate constant for ()NO dissociation from Mb(III)-NO (i.e., for Mb(III) formation) are (1.3+/-0.2)x10(6)M(-1)s(-1) and 7.6+/-1.3s(-1), respectively, at pH 8.3 and 20.0 degrees C. Since ()NO dissociation from Mb(II)-NO is very slow, and (unlike O(2) and CO) ()NO is a ligand for both Mb(II) and Mb(III), Mb(II)-NO can be oxidized without requiring ()NO dissociation. PMID:17562327

Ascenzi, Paolo; Petrella, Giovanni; Coletta, Massimo

2007-08-10

95

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

96

Enhancement of growth and ferrous iron oxidation rates of T. ferrooxidans by electrochemical reduction of ferric iron  

SciTech Connect

Thiobacillus ferrooxidans, the bacterium most widely used in bioleaching or microbial desulfurization of coal, was grown in an electrolytic bioreactor containing a synthetic, ferrous sulfate medium. Passage of current through the medium reduced the bacterially generated ferric iron to the ferrous iron substrate. When used in conjunction with an inoculum that had been adapted to the electrolytic growth conditions, this technique increased the protein (cell) concentration by 3.7 times, increased the protein (cell) production rate by 6.5 times, increased the yield coefficient (cellular efficiency) by 8.0 times, and increased the ferrous iron oxidation rate by 1.5 times at 29/sup 0/C, compared with conventional cultivation techniques. A Monod-type equation with accepted values for the maximum specific growth rate could not account for the increased growth rate under electrolytic conditions.

Yunker, S.B.; Radovich, J.M.

1986-01-01

97

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

98

Oxidation of sulphide minerals-VI Ferrous and ferric iron in the water-soluble oxidation products of iron sulphide minerals.  

PubMed

A pseudo-kinetic method has been developed for determining the ferrous and ferric iron in the water-soluble oxidation products of pyrrhotite, pyrite and chalcopyrite, and ores and concentrates containing them. Two determinations are required for each material. In one, the total iron is determined with 1,10-phenanthroline after reduction to Fe(II). In the other, the reduction of Fe(III) is retarded by complexation with fluoride. The difference in the amount of ferrous phenanthranoline complex produced in these two determinations is a function of the original FE(III) concentration and of time. PMID:18962467

Steger, H F

1979-06-01

99

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

100

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 3000 F. Preferably, the reactor type is a pressurized or boiling water reactor and the nanophase material is a high temperature ceramic or ceramic composite. Nanophase metals, or nanophase metals with nanophase ceramics in a composite mixture, also have desirable characteristics, although their temperature capability is not as great as with all-ceramic nanophase material. Combinations of conventional or nanophase metals and conventional or nanophase ceramics can be employed as long as there is at least one nanophase material in the composite. The nuclear reactor so constructed has a number of high strength fuel particles, a nanophase structural material for supporting a fuel rod at high temperature, a configuration to allow passive cooling in the event of a primary cooling system failure, an ability to retain a coolable geometry even at high temperatures, an ability to resist generation of hydrogen gas, and a configuration having good nuclear, corrosion, and mechanical characteristics. 5 figs.

Heubeck, N.B.

1998-09-08

101

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 3000.degree. F. Preferably, the reactor type is a pressurized or boiling water reactor and the nanophase material is a high temperature ceramic or ceramic composite. Nanophase metals, or nanophase metals with nanophase ceramics in a composite mixture, also have desirable characteristics, although their temperature capability is not as great as with all-ceramic nanophase material. Combinations of conventional or nanophase metals and conventional or nanophase ceramics can be employed as long as there is at least one nanophase material in the composite. The nuclear reactor so constructed has a number of high strength fuel particles, a nanophase structural material for supporting a fuel rod at high temperature, a configuration to allow passive cooling in the event of a primary cooling system failure, an ability to retain a coolable geometry even at high temperatures, an ability to resist generation of hydrogen gas, and a configuration having good nuclear, corrosion, and mechanical characteristics.

Heubeck, Norman B. (Schenectady, NY)

1998-01-01

102

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

PubMed

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

Chauhan, Nidhi; Pundir, C S

2014-11-15

103

Role of Ferric Iron in the Oxidation of Hydrocortisone by Sepiolite and Palygorskite  

Microsoft Academic Search

The role of adsorbed and structural Fe n+ in palygorskite and sepiolite with respect to the oxi- dation of hydrocortisone in aqueous suspension has been evaluated using electron spin resonance and UV- visible spectroscopy. Natural surface-adsorbed Fe 3+ showed an important activity in the oxidation process, although smaller than octahedral Fe 3+. The kinetics of oxidative degradation of hydrocortisone by

J. Cornejo; M. C. HERMOSIN; J. L. WHITE; J. R. BARNES; S. L. HEM

1983-01-01

104

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

105

Mechanical properties of nanophase metals  

SciTech Connect

Nanophase metals have grain-size dependent mechanical properties that are significantly different than those of their coarse-grained counterparts. Pure metals are much stronger and apparently less ductile than conventional ones; intermetallics are also strengthened, but they tend toward increased ductility at the smallest grain sizes. These property changes are primarily related to grain size limitations, but they are also affected by the large percentage of atoms in grain boundaries and other microstructural features. Strengthening appears to result from a limitation of dislocation activity, while increased ductility probably relates to grain boundary sliding. A brief overview of our present understanding of the mechanical properties of nanophase metals 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

1994-11-01

106

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

2009-02-15

107

Direct inhibition by nitric oxide of the transcriptional ferric uptake regulation protein via nitrosylation of the iron  

PubMed Central

Ferric uptake regulation protein (Fur) is a bacterial global regulator that uses iron as a cofactor to bind to specific DNA sequences. The function of Fur is not limited to iron homeostasis. A wide variety of genes involved in various mechanisms such as oxidative and acid stresses are under Fur control. Flavohemoglobin (Hmp) is an NO-detoxifying enzyme induced by NO and nitrosothiol compounds. Fur recently was found to regulate hmp in Salmonella typhimurium, and in Escherichia coli, the iron-chelating agent 2,2?-dipyridyl induces hmp expression. We now establish direct inhibition of E. coli Fur activity by NO. By using chromosomal Fur-regulated lacZ reporter fusion in E. coli, Fur activity is switched off by NO at micromolar concentration. In vitro Fur DNA-binding activity, as measured by protection of restriction site in aerobactin promoter, is directly sensitive to NO. NO reacts with FeII in purified FeFur protein to form a S = 1/2 low-spin FeFur–NO complex with a g = 2.03 EPR signal. Appearance of the same EPR signal in NO-treated cells links nitrosylation of the iron with Fur inhibition. The nitrosylated Fur protein is still a dimer and is stable in anaerobiosis but slowly decays in air. This inhibition probably arises from a conformational switch, leading to an inactive dimeric protein. These data establish a link between control of iron metabolism and the response to NO effects.

D'Autreaux, Benoit; Touati, Daniele; Bersch, Beate; Latour, Jean-Marc; Michaud-Soret, Isabelle

2002-01-01

108

Cellular and Biochemical Response of the Human Lung after Intrapulmonary Instillation of Ferric Oxide Particles  

Microsoft Academic Search

Bronchoalveolar lavage (BAL) was used to sample lung cells and biochemical components in the lung air spaces at various times from 1 to 91 d after intrapulmonary instillation of 2.6 m m-diameter iron oxide par- ticles in human subjects. The instillation of particles induced transient acute inflammation during the first day post instillation (PI), characterized by increased numbers of neutrophils

John C. Lay; William D. Bennett; Andrew J. Ghio; Philip A. Bromberg; Daniel L. Costa; Chong S. Kim; Hillel S. Koren; Robert B. Devlin

1999-01-01

109

Proton Adsorption at the Ferric Oxide/Aqueous Solution Interface. Ii. Analysis of Kinetic Data.  

National Technical Information Service (NTIS)

A quantitative study of the time-dependent abstraction of H(+) and OH(-) ions from solution by crystalline Fe2O3 precipitates is reported. The experimental information was gathered by potentiometric titrations of oxide suspensions, by observation of pH dr...

Y. G. Berube, G. Y. Onoda, P. L. de Bruyn

1967-01-01

110

Growth mechanisms of iron oxide particles of differing morphologies from the forced hydrolysis of ferric chloride solutions  

SciTech Connect

To determine the growth mechanisms responsible for the different morphologies, the authors used time resolved transmission electron microscopy to follow the growth of iron oxide particles produced by the forced hydrolysis of ferric chloride solutions. The growth of three different hematite particle morphologies were investigated: cubes, spheres, and so-called double ellipsoids. The morphology of the particles depends on the concentration of FeCl[sub 3], the pH, and the temperature of aging. All solutions were seen to first produce rod-like particles of akaganeite ([beta]-FeOOH) which would then transform to hematite ([alpha]-Fe[sub 2]O[sub 3]), leading under different conditions to spheres, cubes, or double ellipsoids. For all solutions, the initially produced akaganeite rods form by homogeneous nucleation and subsequent growth. The hematite particles are produced by dissolution of the akaganeite rods and reprecipitation as hematite. For the double-ellipsoid-producing solution, the akaganeite rods remain unaggregated in solution. Hematite heterogeneously nucleates on these rods. In addition to growing outward, the hematite particle uses the rod as a template, and a collar forms, which grows along the rod, producing the double-ellipsoid shape. For a sphere-producing solution, the [beta]-FeOOH rods also remain unaggregated in solution but the akaganeite rods which are formed are shorter and dissolve before the growing hematite particles can use the rods as templates. For the cube-producing solution, the initially produced akaganeite rods aggregate into rafts. These rafts, formed from rods of similar length, have a cubic shape that they impart to the hematite which nucleates on the akaganeite raft. The findings indicate that the concentrations of starting compounds not only influence the kinetics of the reaction, but also influence the colloidal behavior.

Bailey, J.K.; Brinker, C.J. (Sandia National Labs., Albuquerque, NM (United States)); MeCartney, M.L. (Univ. of California, Irvine (United States))

1993-04-01

111

Impact of natural nanophases on heavy-metal retention in zeolite-supported reactive filtration facilities for urban run-off treatment.  

PubMed

The retention of lead in zeolite-supported sand-filter columns has been tested with focus on the effect of potentially mobile natural nanophases (natural colloids, humic substances). It could be shown that interaction of lead with natural nanophases enhanced the mobility of the contaminant. In the presence of iron oxide particles (goethite) a normal breakthrough of lead was observed. Humic substance can act as a carrier for lead itself and can enhance the mobility of lead bound to inorganic nanophases, because of the increased mobility of the nanophases in the presence of humic substances. PMID:11767892

Förstner, U; Jacobs, P; Kammer, F

2001-11-01

112

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2010 CFR

...may be prepared 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....

2010-01-01

113

TEM investigation of nanophase aluminum powder.  

PubMed

Nanophase aluminum powder was characterized in a field-emission-gun transmission electron microscope (TEM). Different techniques were used to investigate the structure of the particles, including conventional bright-field and dark-field imaging, scanning transmission electron microscopy (STEM), high-resolution lattice imaging, diffraction studies, energy dispersive X-ray spectroscopy (EDS) analysis and mapping, and electron energy loss spectroscopy (EELS) analysis and mapping. It has been established that the particle cores consist of aluminum single crystals that sometimes contain crystal lattice defects. The core is covered by a passivating layer of aluminum oxide a few nanometers thick. The alumina is mostly amorphous, but evidences of partial crystallinity of the oxide were also found. The thickness of this layer was measured using different techniques, and the results are in good agreement with each other. The particles are agglomerated in two distinct ways. Some particles were apparently bonded together during processing before oxidation. These mostly form dumbbells covered by a joint oxide layer. Also, oxidized particles are loosely assembled into relatively large clusters. PMID:17481322

Gertsman, Valéry Y; Kwok, Queenie S M

2005-10-01

114

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

115

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

116

Similarity of the Surface Reactivity of Hydrous Ferric Oxide and Hematite: Sorption and Redox of U(VI) and Fe(II)  

SciTech Connect

Hydrous Ferric Oxide (HFO) vs. Hematite--Thermodynamically distinctive bulk phases, but the surfaces could be similar due to hydration of the interface. Hypothesis--The surface of HFO is energetically similar to the surface of hematite. Objective--Compare the reactions of HFO and hematite with U(VI) and Fe(II). Experimental--The reactions of interests were (1) preparation of sub-micron hematite, (2) sorption of U(VI), and (3) redox of U(VI) and Fe(II) with HFO or hematite.

Je-Hun Jang; Dempsey, Brian A.; Burgos, William D.; Yeh, George; Roden, Eric

2004-03-17

117

Oxidative stress markers in predicting response to treatment with ferric carboxymaltose in nondialysis chronic kidney disease patients.  

PubMed

Background: Nearly half of all non-dialysis chronic kidney disease (CKD) patients respond to iron therapy. Factors affecting anemia response to iron therapy are not well characterized. Oxidative stress (OS) is a recognized factor for anemia in CKD and promotes erythropoiesis stimulating agent (ESA) resistance; however, the influence in predicting response to intravenous (IV) iron has not been evaluated. Methods: Patients (n = 47) with non-dialysis CKD stages 3 - 5 (mean eGFR: 26 ± 10.4 mL/min/1.73 m2) and iron-deficiency anemia (hemoglobin < 11 g/dL, transferrin saturation (TSAT) index < 20%, and/or ferritin < 100 ng/mL) received a single injection of 1,000 mg of ferric carboxymaltose (FCM) and were observed for 12 weeks. Based on erythropoietic response (defined as â?¥ 1 g/dL increase in hemoglobin level), patients were classified as responders or non-responders. Baseline conventional markers of iron status (TSAT and ferritin), inflammatory markers (C-reactive protein and IL-6), OS markers (oxidized LDL, protein carbonyl groups, erythrocyte superoxide dismutase, and glutathione peroxidase (GPx)), and catalase activity were measured. Results: FCM resulted in a significant increase in hemoglobin, TSAT, and ferritin (10 ± 0.7 vs. 11.4 ± 1.3 g/dL, p < 0.0001; 14.6 ± 6.4% vs. 28.9 ± 10%, p < 0.0001; 67.8 ± 61.7 vs. 502.5 ± 263.3 ng/dL, p < 0.0001, respectively). Responders and non-responders were 34 (72%) and 13 (28%), respectively. Age, baseline hemoglobin, estimated glomerular filtration rate, parathyroid hormone, and use of ESA or angiotensin-modulating agents were similar in both groups. Responders showed a tendency towards lower TSAT than non-responders (13.6 ± 6.5% vs. 17.2 ± 5.6%, p = 0.06) but similar ferritin levels. Inflammatory markers were similar in both groups. eGPx activity was lower in non-responders compared to responders (103.1 ± 50.9 vs. 144.9 ± 63.1 U/g Hb, p = 0.01, respectively), although the other proteins, lipid oxidation markers, and enzymatic antioxidants did not differ between the two groups. In the multivariate adjusted model, odds (95% CI) for achieving erythropoietic response to FCM were 10.53 (1.25 - 88.16) in the third tertile of eGPX activity and 3.20 (0.56 - 18.0) in the second tertile compared to those in the lowest tertiles (p = 0.02). Conclusions: Decreased eGPx activity has adverse influences on response to FCM, suggesting that impaired erythrocyte antioxidant defense may be involved in the response to iron therapy in CKD patients. PMID:24691014

Prats, Mercedes; Font, Ramon; García, Carmen; Muñoz-Cortés, Mònica; Cabré, Carmen; Jariod, Manel; Romeu, Marta; Giralt, Montserrat; Martinez-Vea, Alberto

2014-06-01

118

Impact of natural nanophases on heavy-metal retention in zeolite-supported reactive filtration facilities for urban run-off treatment  

Microsoft Academic Search

The retention of lead in zeolite-supported sand-filter columns has been tested with focus on the effect of potentially mobile natural nanophases (natural colloids, humic substances). It could be shown that interaction of lead with natural nanophases enhanced the mobility of the contaminant. In the presence of iron oxide particles (goethite) a normal breakthrough of lead was observed. Humic substance can

U. Förstner; P. Jacobs; F. Kammer

2001-01-01

119

Rapid kinetics investigations of peracid oxidation of ferric cytochrome P450cam: Nature and possible function of compound ES  

Microsoft Academic Search

Previously, we reported spectroscopic properties of cytochrome P450cam compound I, (ferryl iron plus a porphyrin ?-cation radical (FeIV=O\\/Por+)), as well as compound ES (FeIV=O\\/Tyr) in reactions of substrate-free ferric enzyme with m-chloroperbenzoic acid [T. Spolitak, J.H. Dawson, D.P. Ballou, J. Biol. Chem. 280 (2005) 20300-9]. Compound ES arises by intramolecular electron transfer from nearby tyrosines to the porphyrin ?-cation radical

Tatyana Spolitak; John H. Dawson; David P. Ballou

2006-01-01

120

Interactions between substrates and the haem-bound nitric oxide of ferric and ferrous bacterial nitric oxide synthases  

PubMed Central

We report here the resonance Raman spectra of the FeIII–NO and FeII–NO complexes of the bacterial NOSs (nitric oxide synthases) from Staphylococcus aureus and Bacillus subtilis. The haem–NO complexes of these bacterial NOSs displayed Fe–N–O frequencies similar to those of the mammalian NOSs, in presence and absence of L-arginine, indicating that haem-bound NO and L-arginine had similar haem environments in bacterial and mammalian NOSs. The only notable difference between the two types of NOS was the lack of change in Fe–N–O frequencies of the FeIII–NO complexes upon (6R) 5,6,7,8-tetrahydro-L-biopterin binding to bacterial NOSs. We report, for the first time, the characterization of NO complexes with NOHA (N?-hydroxy-L-arginine), the substrate used in the second half of the catalytic cycle of NOSs. In the FeIII–NO complexes, both L-arginine and NOHA induced the Fe–N–O bending mode at nearly the same frequency as a result of a steric interaction between the substrates and the haem-bound NO. However, in the FeII–NO complexes, the Fe–N–O bending mode was not observed and the ?Fe?NO mode displayed a 5 cm?1 higher frequency in the complex with NOHA than in the complex with L-arginine as a result of direct interactions that probably involve hydrogen bonds. The different behaviour of the substrates in the FeII–NO complexes thus reveal that the interactions between haem-bound NO and the substrates are finely tuned by the geometry of the Fe-ligand structure and are relevant to the use of the FeII–NO complex as a model of the oxygenated complex of NOSs.

Chartier, Francois J. M.; Couture, Manon

2006-01-01

121

Rapid kinetics investigations of peracid oxidation of ferric cytochrome P450cam: nature and possible function of compound ES.  

PubMed

Previously, we reported spectroscopic properties of cytochrome P450cam compound I, (ferryl iron plus a porphyrin pi-cation radical (Fe(IV)=O/Por(+))), as well as compound ES (Fe(IV)=O/Tyr()) in reactions of substrate-free ferric enzyme with m-chloroperbenzoic acid [T. Spolitak, J.H. Dawson, D.P. Ballou, J. Biol. Chem. 280 (2005) 20300-9]. Compound ES arises by intramolecular electron transfer from nearby tyrosines to the porphyrin pi-cation radical of Compound I, and has been characterized by rapid-freeze-quench-Mössbauer/EPR spectroscopy; the tyrosyl radical was assigned to Tyr96 for wild type or to Tyr75 for the Tyr96Phe variant [V. Schünemann, F. Lendzian, C. Jung, J. Contzen, A.L. Barra, S.G. Sligar, A.X. Trautwein, J. Biol. Chem. 279 (2004) 10919-10930]. Here we report rapid-scanning stopped-flow studies of the reactions of peracids with substrate-free ferric Y75F, Y96F, and Y96F/Y75F P450cam variants, showing how these active site changes influence electron transfer from nearby tyrosines and affect formation of intermediates. Curiously, rates of generation of Compounds I and ES for both single mutants were not very different from wild type. Contrasting with the earlier EPR results, the Y96F/Y75F variant was also shown to form an ES-like species, but more slowly. When substrate is not present, or is improperly bound, compound I rapidly converts to compound ES, which can be reduced to form H(2)O and ferric P450, thus avoiding the modification of nearby protein groups or release of reactive oxygen species. PMID:17095096

Spolitak, Tatyana; Dawson, John H; Ballou, David P

2006-12-01

122

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

PubMed

Sewage sludge of biological wastewater treatment plant was converted into sewage sludge based activated carbon (SBAC) with ZnCl2 as activation agent, which supported manganese and ferric oxides as catalysts (including SBAC) to improve the performance of ozonation of real biologically pretreated Lurgi coal gasification wastewater. The results indicated catalytic ozonation with the prepared catalysts significantly enhanced performance of pollutants removal and the treated wastewater was more biodegradable and less toxic than that in ozonation alone. On the basis of positive effect of higher pH and significant inhibition of radical scavengers in catalytic ozonation, it was deduced that the enhancement of catalytic activity was responsible for generating hydroxyl radicals and the possible reaction pathway was proposed. Moreover, the prepared catalysts showed superior stability and most of toxic and refractory compounds were eliminated at successive catalytic ozonation runs. Thus, the process with economical, efficient and sustainable advantages was beneficial to engineering application. PMID:24907577

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

2014-08-01

123

Matrix effects for reflectivity spectra of dispersed nanophase (superparamagnetic) hematite with application to Martian spectral data  

NASA Astrophysics Data System (ADS)

The effect of the matrix on the reflectivity spectra of nanophase (superparamagnetic) hematite (np-Hm) dispersed within the matrix was investigated in four series of powder samples containing np-Hm dispersed within discrete powder particles (of two size ranges) of silica gel and activated alumina. The spectral data show that matrix effects are large. Samples with the same Fe2O3 content can have np-Hm absorption edges characterized by very different positions and curvature and slope indices, while samples with equivalent absorption edges can have very different Fe2O3 concentrations. Thus, quantitative relationships between the positions of ferric absorption edges and Fe2O3 concentrations are unreliable without knowledge of matrix properties of the system. It is shown that it was possible to match the Fe2O3 concentration, magnetic properties, and spectral data for Martian surface material with a laboratory mixture whose only ferric-bearing phase was hematite.

Morris, R. V.; Lauer, H. V.

1990-04-01

124

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

SciTech Connect

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

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

2013-11-29

125

Arsenic removal by ferric chloride  

SciTech Connect

Bench-scale studies were conducted in model freshwater systems to investigate how various parameters affected arsenic removal during coagulation with ferric chloride and arsenic adsorption onto preformed hydrous ferric oxide. Parameters included arsenic oxidation state and initial concentration, coagulant dosage or adsorbent concentration, pH, and the presence of co-occurring inorganic solutes. Comparison of coagulation and adsorption experiments and of experimental results with predictions based on surface complexation modeling demonstrated that adsorption is an important (though not the sole) mechanism governing arsenic removal during coagulation. Under comparable conditions, better removal was observed with arsenic(V) [As(V)] than with arsenic(III) [As(III)] in both coagulation and adsorption experiments. Below neutral pH values, As(III) removal-adsorption was significantly decreased in the presence of sulfate, whereas only a slight decrease in As(V) removal-adsorption was observed. At high pH, removal-adsorption of As(V) was increased in the presence of calcium. Removal of As(V) during coagulation with ferric chloride is both more efficient and less sensitive than that of As(III) to variations in source water composition.

Hering, J.G.; Chen, P.Y.; Wilkie, J.A.; Elimelech, M. [Univ. of California, Los Angeles, CA (United States). Dept. of Civil and Environmental Engineering; Liang, S. [Metropolitan Water District of Southern California, La Verne, CA (United States)

1996-04-01

126

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

127

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

Microsoft Academic Search

The presence of Fe-oxidizing bacteria in the rhizosphere of four different species of wetland plants was investigated in a diverse wetland environment that had Fe(II) concentrations ranging from tens to hundreds of micromoles per liter and a pH range of 3.5 to 6.8. Enrichments for neutrophilic, putatively lithotrophic Fe-oxidizing bacteria were successful on roots from all four species; acidophilic Fe-oxidizing

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

1999-01-01

128

Bacterial Reduction of Copper-Contaminated Ferric Oxide: Copper Toxicity and the Interaction Between Fermentative and Iron-Reducing Bacteria  

Microsoft Academic Search

.   Fe(III) oxide is an important heavy-metal sink, and bacteria are responsible for much of the Fe(III) reduced in nonsulfidogenic\\u000a aquatic environments, yet factors governing the bacterial reduction of heavy metal–contaminated iron oxide are largely unknown.\\u000a In this study with a stabilized bacterial consortium enriched from metal-contaminated sediments, we demonstrate that Cu toxicity\\u000a impedes anaerobic carbon oxidation and bacterial reduction

J. T. Markwiese; P. J. S. Colberg

2000-01-01

129

Hydrolysis of ferric chloride in solution  

Microsoft Academic Search

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

G. Lussiez; L. Beckstead

1996-01-01

130

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

PubMed Central

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

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

1999-01-01

131

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

132

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

133

Sugarcane bagasse treated with hydrous ferric oxide as a potential adsorbent for the removal of As(V) from aqueous solutions.  

PubMed

The mechanism of As(V) removal from aqueous solutions by means of hydrated ferric oxide (HFO)-treated sugarcane bagasse (SCB-HFO) (Saccharum officinarum L.) was investigated. Effects of different parameters, such as pH value, initial arsenic concentration, adsorbent dosage, contact time and ionic strength, on the As(V) adsorption were studied. The adsorption capacity of SCB-HFO for As(V) was found to be 22.1 mg/g under optimum conditions of pH 4, contact time 3h and temperature 22 °C. Initial As(V) concentration influenced the removal efficiency of SCB-HFO. The desorption of As(V) from the adsorbent was 17% when using 30% HCl and 85% with 1M NaOH solution. FTIR analyses evidenced two potential binding sites associated with carboxyl and hydroxyl groups which are responsible for As(V) removal. Adsorption, surface precipitation, ion exchange and complexation can be suggested as mechanisms for the As(V) removal from the solution phase onto the surface of SCB-HFO. PMID:23265467

Pehlivan, E; Tran, H T; Ouédraogo, W K I; Schmidt, C; Zachmann, D; Bahadir, M

2013-05-01

134

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

PubMed Central

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

Caccavo, Frank

1999-01-01

135

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

SciTech Connect

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

Caccavo, F. Jr.

1999-11-01

136

Combined hydrous ferric oxide and quaternary ammonium surfactant tailoring of granular activated carbon for concurrent arsenate and perchlorate removal  

Microsoft Academic Search

Activated carbon was tailored with both iron and quaternary ammonium surfactants so as to concurrently remove both arsenate and perchlorate from groundwater. The iron (hydr)oxide preferentially removed the arsenate oxyanion but not perchlorate; while the quaternary ammonium preferentially removed the perchlorate oxyanion, but not the arsenate. The co-sorption of two anionic oxyanions via distinct mechanisms has yielded intriguing phenomena. Rapid

Min Jang; Fred S. Cannon; Robert B. Parette; Soh-joung Yoon; Weifang Chen

2009-01-01

137

Reduction in nitric oxide synthase activity with development of an epileptogenic focus induced by ferric chloride in the rat brain  

Microsoft Academic Search

Intracortical injection of iron ion has been shown to induce recurrent seizures and epileptic discharges in electrocorticograms. The importance of the effects of NO on seizure control systems and their regulation is suggested. In this paper, we examined the changes in nitric oxide synthase (NOS) activity in the epileptogenic focus induced by intracortical injection of iron ion at 5 min,

Hideaki Kabuto; Isao Yokoi; Hitoshi Habu; L. James Willmore; Akitane Mori; Norio Ogawa

1996-01-01

138

Mineralogy of a natural As-rich hydrous ferric oxide coprecipitate formed by mixing of hydrothermal fluid and seawater: Implications regarding surface complexation and color banding in ferrihydrite deposits  

Microsoft Academic Search

We characterized the most As-rich natural hydr ous ferric oxide (HFO) material ever reported using powder X-ray diffraction (pXRD), transmission electron microscopy (TEM), X-ray fluores- cence spectroscopy (XRF), light element analysis using gas chromatography (GC), visible-infrared (vis-IR) diffuse reflectivity, 57 Fe Mössbauer spectroscopy, and superconducting quantum interfer- ence device (SQUID) magnetometry. We find that the natural As-HFO material is very

DENIS G. RANCOURT; DANIELLE FORTIN; THOMAS PICHLER; P IERRE-JEAN THIBAULT; GILLES LAMARCHE; RICHARD V. M ORRIS; PATRICK H. J. MERCIER

2001-01-01

139

Combined hydrous ferric oxide and quaternary ammonium surfactant tailoring of granular activated carbon for concurrent arsenate and perchlorate removal.  

PubMed

Activated carbon was tailored with both iron and quaternary ammonium surfactants so as to concurrently remove both arsenate and perchlorate from groundwater. The iron (hydr)oxide preferentially removed the arsenate oxyanion but not perchlorate; while the quaternary ammonium preferentially removed the perchlorate oxyanion, but not the arsenate. The co-sorption of two anionic oxyanions via distinct mechanisms has yielded intriguing phenomena. Rapid small-scale column tests (RSSCTs) with these dually prepared media employed synthetic waters that were concurrently spiked with arsenate and perchlorate; and these trial results showed that the quaternary ammonium surfactants enhanced arsenate removal bed life by 25-50% when compared to activated carbon media that had been preloaded merely with iron (hydr)oxide; and the surfactant also enhanced the diffusion rate of arsenate per the Donnan effect. The authors also employed natural groundwater from Rutland, MA which contained 60 microg/L As and traces of silica, and sulfate; and the authors spiked this with 40 microg/L perchlorate. When processing this water, activated carbon that had been tailored with iron and cationic surfactant could treat 12,500 bed volumes before 10 microg/L arsenic breakthrough, and 4500 bed volumes before 6 microg/L perchlorate breakthrough. Although the quaternary ammonium surfactants exhibited only a slight capacity for removing arsenate, these surfactants did facilitate a more favorably positively charged avenue for the arsenate to diffuse through the media to the iron sorption site (i.e. via the Donnan effect). PMID:19476961

Jang, Min; Cannon, Fred S; Parette, Robert B; Yoon, Soh-Joung; Chen, Weifang

2009-07-01

140

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

141

Preparation of manganese(II), chromium(III) and ferric(III) oxides nanoparticles in situ metal citraconate complexes frameworks.  

PubMed

The new reactions of some divalent and trivalent transition metal ions (Mn(II), Cr(III), and Fe(III)) with citraconic acid has been studied. The obtained results indicate the formation of citraconic acid compounds with molar ratio of metal to citraconic acid of 2:2 or 2:3 with general formulas Mn2(C5H4O4)2 or M2(C5H4O4)3?nH2O where n=6 for Cr, and Fe(III). The thermal decomposition of the crystalline solid complexes was investigated. The IR spectra of citraconate suggested that the carboxylic groups are bidentatically bridging and chelating. In the course of decomposition the complexes are dehydrated and then decompose either directly to oxides in only one step or with intermediate formation of oxocarbonates. This proposal dealing the preparation of MnO2, Fe2O3 and Cr2O3 nanoparticles. The crystalline structure of oxide products were checked by X-ray powder diffraction (XRD), and the morphology of particles by scanning electron microscopy (SEM). PMID:24952090

Refat, Moamen S

2014-12-10

142

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

143

21 CFR 184.1301 - Ferric phosphate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Ferric phosphate. 184.1301 Section 184.1301 Food and...Substances Affirmed as GRAS § 184.1301 Ferric phosphate. (a) Ferric phosphate (ferric orthophosphate, iron (III)...

2013-04-01

144

Nanophase, Low-Ni Metal Grains in Fine-grained Rims in the Murchison CM2 Chondrite: Insights into the Survival of Metal Grains During Aqueous Alteration  

NASA Astrophysics Data System (ADS)

TEM and EFTEM studies reveal partially oxidized nanophase kamacite grains in fine-grained rims in Murchison. The grains are rimmed by amorphous carbon and magnetite. We suggest that the carbon layer protected the metal from full oxidation during parent body aqueous alteration.

Brearley, A. J.

2003-03-01

145

Evaluation of electron-shuttling compounds in microbial ferric iron reduction  

Microsoft Academic Search

Iron-reducing bacteria can transfer electrons to ferric iron oxides which are barely soluble at neutral pH, and electron-shuttling compounds or chelators are discussed to be involved in this process. Experiments using semipermeable membranes for separation of ferric iron-reducing bacteria from ferric iron oxides do not provide conclusive results in this respect. Here, we used ferrihydrite embedded in 1% agar to

Kristina L. Straub; Bernhard Schink

2003-01-01

146

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

147

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

148

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

149

SURFACE PRETREATMENT STUDIES ON AA2024-T3 FOR OPTIMAL SELF-ASSEMBLED NANO-PHASE PARTICLE (SNAP) SOL-GEL APPLICATION  

Microsoft Academic Search

As part of the Air Force's goal to replace chromates in the current aircraft coating systems, Self- assembled NAno-phase Particle (SNAP) sol-gel films on aluminum alloys have been shown to provide a good barrier to corrosion. Surface preparation is an important step in a paint system to prepare the substrate's native oxide for increased adhesion and corrosion protection. As SNAP

L. S. Kasten; N. N. Voevodin; R. J. Miller; M. S. Donley

150

Nanophase Alumina/Poly(L-Lactic Acid) Composite Scaffolds for Biomedical Applications.  

National Technical Information Service (NTIS)

Three-dimensional composites of nanophase alumina and poly(L-lactic acid) with an interconnected porous network and an overall porosity in excess of 90% are cytocompatible. Osteoblast proliferation on the nanophase ceramic/ polymer composites is a functio...

A. J. Tulloch R. Bizios R. W. Siegel

2003-01-01

151

Highly selective synthesis of the ring-B reduced chlorins by ferric chloride-mediated oxidation of bacteriochlorins: effects of the fused imide vs isocyclic ring on photophysical and electrochemical properties.  

PubMed

The oxidation of bacteriopyropheophorbide with ferric chloride hexahydrate or its anhydrous form produced the ring-D oxidized (ring-B reduced) chlorin in >95% yield. Replacing the five-member isocyclic ring in bacteriopyropheophorbide- a with a fused six-member N-butylimide ring system made no difference in regioselective oxidation, and the corresponding ring-B reduced chlorin was isolated in almost quantitative yield. When the oxidant was replaced by 2,3-dichloro-5,6-dicyano-p-benzoquinone, which is frequently used at the oxidizing stage of the porphyrin synthesis, the ring-B oxidized (ring-D reduced) chlorins were obtained. With both ring-B reduced and ring-D reduced chlorins in hand, their photophysical and electrochemical properties were examined and compared for the first time. The ring-B reduced chlorine 20, with a fused six-member N-butylimide ring, exhibits the most red-shifted absorption band (at lambda(max) = 746 nm), the lowest fluorescence quantum yield (4.5%), and the largest quantum yield of singlet oxygen formation (67%) among the reduced ring-B and ring-D chlorins investigated in this study. Measurements of the one-electron oxidation and reduction potentials show that compound 20 is also the easiest to oxidize among the examined compounds and the third easiest to reduce. In addition, the 1.62 eV HOMO-LUMO gap of 20 is the smallest of the examined compounds, and this agrees with values calculated using the DFT method. Spectroelectrochemical measurements afforded UV-visible absorption spectra for both the radical cations and radical anions of the examined chlorins. The ring-B reduced compound 20, with a fused six-member N-butylimide ring, is regarded as the most promising candidate in this study for photodynamic therapy because it has the longest wavelength absorption and the largest quantum yield of singlet oxygen formation among the compounds investigated. PMID:18828591

Liu, Chao; Dobhal, Mahabeer P; Ethirajan, Manivannan; Missert, Joseph R; Pandey, Ravindra K; Balasubramanian, Sathyamangalam; Sukumaran, Dinesh K; Zhang, Min; Kadish, Karl M; Ohkubo, Kei; Fukuzumi, Shunichi

2008-10-29

152

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

Microsoft Academic Search

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 °C and 70 °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

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

2003-01-01

153

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

154

The Center for Nanophase Materials Sciences  

NASA Astrophysics Data System (ADS)

The Center for Nanophase Materials Sciences (CNMS) located at Oak Ridge National Laboratory (ORNL) will be the first DOE Nanoscale Science Research Center to begin operation, with construction to be completed in April 2005 and initial operations in October 2005. The CNMS' scientific program has been developed through workshops with the national community, with the goal of creating a highly collaborative research environment to accelerate discovery and drive technological advances. Research at the CNMS is organized under seven Scientific Themes selected to address challenges to understanding and to exploit particular ORNL strengths (see http://cnms.ornl.govhttp://cnms.ornl.gov). These include extensive synthesis and characterization capabilities for soft, hard, nanostructured, magnetic and catalytic materials and their composites; neutron scattering at the Spallation Neutron Source and High Flux Isotope Reactor; computational nanoscience in the CNMS' Nanomaterials Theory Institute and utilizing facilities and expertise of the Center for Computational Sciences and the new Leadership Scientific Computing Facility at ORNL; a new CNMS Nanofabrication Research Laboratory; and a suite of unique and state-of-the-art instruments to be made reliably available to the national community for imaging, manipulation, and properties measurements on nanoscale materials in controlled environments. The new research facilities will be described together with the planned operation of the user research program, the latter illustrated by the current ``jump start'' user program that utilizes existing ORNL/CNMS facilities.

Lowndes, Douglas

2005-03-01

155

The potential of magnetic force microscopy for in-situ investigation of nanophase iron in lunar dust  

NASA Astrophysics Data System (ADS)

Lunar dust is known to contain nanophase iron (np-Fe), which is suspected to be toxic. These magnetic nanoparticles have a diameter in the lower nanometre range and are enclosed in a glassy rim produced by space weathering. The np-Fe must be exposed in order to develop its toxicity and, hence, an instrument for in-situ assessing the location of np-Fe on soil particles would be needed. This contribution proposes a method for such in-situ analysis of np-Fe and its distribution on dust and soil particles. Magnetic nanophase iron oxide is used to demonstrate that magnetic force microscopy can detect single imbedded magnetic nanoparticles of 30 nm and differentiate them from magnetic or non-magnetic nanoparticles at the surface.

Kohl, D.; Schitter, G.; Staufer, U.

2012-12-01

156

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

157

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

Microsoft Academic Search

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

Tomohisa Hirobe

2009-01-01

158

Mono- and Polynuclear Ferric Nucleotides. II. Reactions of Ferric Iron with Adenosine and Adenosine Phosphates.  

National Technical Information Service (NTIS)

The formation and physical properties of monoand polynuclear ferric nucleotides have been investigated. The ferric nucleotide chelates are readily formed in an alkaline medium. One mole of nucleotide can solubilize as many as four gram atoms of ferric iro...

C. R. Goucher E. H. Strickland

1964-01-01

159

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

160

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...

161

Carbothermic reaction process for making nanophase WC-Co powders  

Microsoft Academic Search

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

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

1993-01-01

162

Inhibition of uranium(VI) sorption on titanium dioxide by surface iron(III) species in ferric oxide/titanium dioxide systems.  

PubMed

Uranium (U(VI)) sorption in systems containing titanium dioxide (TiO(2)) and various Fe(III)-oxide phases was investigated in the acidic pH range (pH 2.5-6). Studies were conducted with physical mixtures of TiO(2) and ferrihydrite, TiO(2) with coprecipitated ferrihydrite, and with systems where Fe(III) was mostly present as crystalline Fe(III) oxides. The presence of ferrihydrite resulted in decreased U(VI) sorption relative to the pure TiO(2) systems, particularly below pH 4, an unexpected result given that the presence of another sorbent would be expected to increase U(VI) uptake. In mixtures of TiO(2) and crystalline Fe(III) oxide phases, U(VI) sorption was higher than for the analogous mixtures of TiO(2) with ferrihydrite, and was similar to U(VI) sorption on TiO(2) alone. X-ray absorption spectroscopy of the TiO(2) system with freshly precipitated Fe(III) oxides indicated the presence of an Fe(III) surface phase that inhibits U(VI) sorption-a reaction whereby Fe(III) precipitates as lepidocrocite and/or ferrihydrite effectively blocking surface sorption sites on the underlying TiO(2). Competition between dissolved Fe(III) and U(VI) for sorption sites may also contribute to the observed decrease in U(VI) sorption. The present study demonstrates the complexity of sorption in mixed systems, where the oxide phases do not necessarily behave in an additive manner, and has implications for U(VI) mobility in natural and impacted environments where Fe(III) (oxyhydr)oxides are usually assumed to increase the retention of U(VI). PMID:23013221

Comarmond, M Josick; Payne, Timothy E; Collins, Richard N; Palmer, Gabriel; Lumpkin, Gregory R; Angove, Michael J

2012-10-16

163

Ferric oxyhydroxide microparticles in water  

PubMed Central

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 [Fe3+] [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 ?m to greater than 5 ?m. 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 Å. 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 m2/g determined for laboratory precipitates gave computed decreases in pK of 0.4 to 1.6 units. ImagesFIGURE 1.FIGURE 3.FIGURE 3.FIGURE 4.

Whittemore, Donald O.; Langmuir, Donald

1974-01-01

164

Processing and performance of nanophased braided carbon\\/epoxy composites  

Microsoft Academic Search

A systematic study has been carried out to investigate mechanical properties of 2D nanophased braided carbon\\/epoxy composites. SC-15 epoxy with three types of braided fabrics: ±45°, 0\\/±45°, and 0\\/±60° was used to fabricate composite laminates using vacuum assisted resin infusion molding (VARIM) process. Low-velocity impact (LVI), ultrasonic nondestructive evaluation (NDE) and 3-point bend flexure studies were carried out on biaxial

Mahesh V. Hosur; Shaik Jeelani

2010-01-01

165

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

166

Influence of humic acids on the adsorption of Basic Yellow 28 dye onto an iron organo-inorgano pillared clay and two hydrous ferric oxides.  

PubMed

Effect of humic acids (HAs), macromolecules from natural organic matter, on the adsorption of Basic Yellow 28 is the aim of the present work. Three adsorbents were investigated in this study: an iron organo-inorgano pillared clay and two synthetic Hydrous Iron Oxide (Goethite and HFO). The surface charge was positive in the pH range of this study for the pillared clay; in contrast, it changes from positive to negative when the pH value increased (pH>9) for the two (oxy)hydroxides. Pseudo-first order kinetic rate constants and adsorption capacities increase from humic acid to BY 28. Adsorption isotherms of BY 28 and HA in single component were analysed using the Freundlich equation. Adsorption capacities increased sharply when the pH value of the dye solution was raised from 3 to 9. Increasing the pH medium from 3 to 9 reduces the HA adsorption capacities onto Fe-SMPM and iron oxyhydroxides, respectively. Fitting between measured and predicted sorption capacities of BY 28 and HA in a binary component system indicates that the Sheindorf-Rebuhn-Sheintuch (SRS) model, an extended Freundlich model, is able to describe the simultaneous adsorption of BY 28 and HA. Humic acids favourably affect the adsorption of BY 28, and a cooperative mechanism could be suggested. The synergetic effect existing between BY 28 and HA is shown by the interaction coefficients ?12, which are generally high and increase with pH. Some phenomena have been advanced to explain this mechanism. PMID:23332940

Zermane, Faiza; Cheknane, Benamar; Basly, Jean Philippe; Bouras, Omar; Baudu, Michel

2013-04-01

167

Influence of ferric iron on the electrochemical behavior of pyrite  

Microsoft Academic Search

The electrochemical behavior of a pyrite electrode in a sulfuric acid solution with different concentrations of ferric iron\\u000a (Fe3+) was investigated using electrochemical techniques including measurements of open circuit potential, cyclic voltammetry,\\u000a Tafel polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the pyrite oxidation process\\u000a takes place via a two-step reaction at the interface of the pyrite

Yun Liu; Zhi Dang; PingXiao Wu; Jing Lu; Xiaohua Shu; Liuchun Zheng

2011-01-01

168

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

169

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

National Technical Information Service (NTIS)

The objectives of this proposed research were: (1) 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...

K. G. Tushar

2008-01-01

170

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

PubMed

The design of nanophase titania/poly-lactic-co-glycolic acid (PLGA) composites offers an exciting approach to combine the advantages of a degradable polymer with nano-size ceramic grains to optimize physical and biological properties for bone regeneration. Importantly, nanophase titania mimics the size scale of constituent components of bone since it is a nanostructured composite composed of nanometre dimensioned hydroxyapatite well dispersed in a mostly collagen matrix. For these reasons, the objective of the present in vitro study was to investigate osteoblast (bone-forming cell) adhesion and long-term functions on nanophase titania/PLGA composites. Since nanophase titania tended to significantly agglomerate when added to polymers, different sonication output powers were applied in this study to improve titania dispersion. Results demonstrated that the dispersion of titania in PLGA was enhanced by increasing the intensity of sonication and that greater osteoblast adhesion correlated with improved nanophase titania dispersion in PLGA. Moreover, results correlated better osteoblast long-term functions, such as alkaline phosphatase activity and calcium-containing mineral deposition, on nanophase titania/PLGA composites compared to plain PLGA. In fact, the greatest collagen production by osteoblasts occurred when cultured on nanophase titania sonicated in PLGA at the highest powers. In this manner, the present study demonstrates that PLGA composites with well dispersed nanophase titania can enhance osteoblast functions necessary for improved bone tissue engineering applications. PMID:21727482

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

2005-07-01

171

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

NASA Astrophysics Data System (ADS)

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

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

2005-07-01

172

Method of treating inflammatory diseases using a radiolabeled ferric hydroxide calloid  

DOEpatents

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

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

1992-01-01

173

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

174

Recovery of scrap iron metal value using biogenerated ferric iron.  

PubMed

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

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

2006-04-20

175

NMR study of cluster-assembled nanophase copper  

SciTech Connect

{sup 63}Cu and {sup 65}Cu NMR spectra from cluster-assembled nanophase copper with an average grain size between 5 and 10mn show a broadened peak, at the normal Knight-shifted frequency for copper meta which arises from only the central 1/2 to -1/2 transition. A very broad background is observed on either side of that peak. Some samples exhibit a second broad peak at a position normally associated with non-metallic copper. Pulsed NMR measurements of the central peak show that virtually all the copper signals are significantly broadened and have a spin-spin relaxation time longer than larger grained copper samples. Line shape measurements, using spin echoes, as a function of delay between rf excitation and measurement show there are a number of copper sites with longer relaxation times which have a significantly larger broadening. Those sites are tentatively identified as being at or near a grain boundary or free surface. A small orientation effect is observed indicating an anisotropy within the samples. An isochronal anneal of one sample showed significant, but not complete, line narrowing after an anneal at 450C consistent with other nanophase metals which show grain growth above 40--50% of the melting temperature.

Suits, B.H.; Meng, M. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Physics; Siegel, R.W.; Liao, Y.X. [Argonne National Lab., IL (United States)

1992-12-01

176

NMR study of cluster-assembled nanophase copper  

SciTech Connect

[sup 63]Cu and [sup 65]Cu NMR spectra from cluster-assembled nanophase copper with an average grain size between 5 and 10mn show a broadened peak, at the normal Knight-shifted frequency for copper meta which arises from only the central 1/2 to -1/2 transition. A very broad background is observed on either side of that peak. Some samples exhibit a second broad peak at a position normally associated with non-metallic copper. Pulsed NMR measurements of the central peak show that virtually all the copper signals are significantly broadened and have a spin-spin relaxation time longer than larger grained copper samples. Line shape measurements, using spin echoes, as a function of delay between rf excitation and measurement show there are a number of copper sites with longer relaxation times which have a significantly larger broadening. Those sites are tentatively identified as being at or near a grain boundary or free surface. A small orientation effect is observed indicating an anisotropy within the samples. An isochronal anneal of one sample showed significant, but not complete, line narrowing after an anneal at 450C consistent with other nanophase metals which show grain growth above 40--50% of the melting temperature.

Suits, B.H.; Meng, M. (Michigan Technological Univ., Houghton, MI (United States). Dept. of Physics); Siegel, R.W.; Liao, Y.X. (Argonne National Lab., IL (United States))

1992-12-01

177

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

178

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

179

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

180

The dissolution of sphalerite in ferric sulfate media  

NASA Astrophysics Data System (ADS)

The dissolution of sphalerite, (Zn,Fe)S, in ferric sulfate media was investigated using closely sized fractions of crushed sphalerite crystals. Linear kinetics were observed, and the rate increased in proportion to the surface area, as the average particle size of the sphalerite decreased. The predominant reaction products are ZnSO4, FeSO4, and elemental sulfur. The leaching rate increases with increasing temperature, and the apparent activation energy is 44 kJ/mol. The relatively high apparent activation energy suggests that the rate is chemically controlled, a conclusion supported by the insensitivity of the rate of the rotation speed that was observed in complementary rotating disk experiments. The rate increases as the 0.3 to 0.4 power of the Fe(SO4)1.5 concentration, and is nearly independent of the pulp density, in the presence of a stoichiometric excess of ferric sulfate. In 0.3 M Fe(SO4)1.5 media, the rate increases with increasing acid concentrations >0.1 M H2SO4, but is insensitive to more dilute acid concentrations. In the absence of ferric ions, the rate increases rapidly with increasing H2SO4 concentrations, and relatively rapid rates are observed in solutions containing >0.5 M H2SO4. The rate decreases with increasing initial concentrations of ZnSO4, MgSO4, or FeSO4 in the ferric sulfate leaching solution, and this emphasizes the importance of maintaining the dissolved iron in a fully oxidized state in a commercial leaching operation.

Dutrizac, J. E.

2006-04-01

181

Nanophase separation and hindered glass transition in side-chain polymers  

Microsoft Academic Search

Nanophase separation on length scales of 1-5 nanometres has been reported previously for small-molecule liquids, metallic glasses and also for several semicrystalline, liquid-crystalline and amorphous polymers. Here we show that nanophase separation of incompatible main and side-chain parts is a general phenomenon in amorphous side-chain polymers with long alkyl groups. We conclude from X-ray scattering and relaxation spectroscopy data for

Mario Beiner; Heiko Huth

2003-01-01

182

Performance and characterization of a nanophased porous hydroxyapatite for protein chromatography.  

PubMed

Nanophased porous hydroxyapatite beads with particle diameters of 25 microm and 30 microm intended for use in protein and biomolecule separation are characterized with respect to chromatographic characteristics. These particles were produced from a hydroxyapatite gel by a controlled spray process yielding microspheres containing hydroxyapatite nanocrystals. By calcification of the microspheres, nanophased porous hydroxyapatite beads were obtained. As a reference material, ceramic hydroxyapatite Types I and II with a particle diameter of 40 microm was chosen. SEM pictures show that the surface of the nanophased hydroxyapatite is very rough compared to ceramic hydroxyapatite Types I and Type II. The calcium-to-phosphorous ratio of this nanophased hydroxyapatite is 1.6, which is slightly below the theoretical ratio of 1.67 of pure hydroxyapatite. The porosity is greater than 60%. An IgG binding capacity of 60.7 mg/ml for Bio-Rad Type I and 36.0 mg/ml for Type II, 42.0 mg/ml for the nanophased material with 25 microm and 19.7 mg/ml for the nanophased material with 30 microm were observed. The nanophased material with 30 microm had the lowest mass transfer resistancy as indicated by the dependency of the dynamic binding capacity on velocity. It is assumed that the mass transport properties are characterized by a low particle diffusion resistancy or by slight intraparticle convection. The material also showed high selectivity for IgG. When culture supernatant with 5% FCS containing 3 mg/ml was loaded, pure IgG could be eluted by linear gradient with increasing sodium phosphate concentration. This nanophased material comprises a novel stationary phase for IgG separation. PMID:15281111

Jungbauer, Alois; Hahn, Rainer; Deinhofer, Karin; Luo, Ping

2004-08-01

183

NMR spectra of cluster-assembled nanophase metals  

SciTech Connect

Room temperature nuclear magnetic resonance (NMR) lineshapes are presented for cluster-assembled nanophase Cu and Ag with various grain sizes as measured using TEM. Both the {sup 65}Cu and {sup 63}Cu resonances are measured and compared. Both Cu isotopes are subject to Knight shifts and to couplings to the electric field gradients in the sample. The Cu NMR spectra have a strong central response which is broader but with an average Knight shift virtually identical to a large trained Cu sample. Though measureable signals can be seen for over a MHz, there is no evidence of Cu signal intensity centered at the non-Knight shifted (e.g. insulating) frequency. The Ag signals are measured at a much lower frequency and have reduced sensitivity but, since Ag has a nuclear spin of 1/2, the couplings to the electric field gradients are not present. The results are discussed in terms of predictions made using simple structural models.

Suits, B.H. [Michigan Tech. Univ., MI (United States); Siegel, R.W.; Liao, Y.X. [Argonne National Lab., Chicago, IL (United States)

1992-12-01

184

Selection of Leptospirillum ferrooxidans SRPCBL and development for enhanced ferric regeneration in stirred tank and airlift column reactor.  

PubMed

Presence of Leptospirillum ferrooxidans plays significant role in ferric sulphate generation during bioleaching process. Thus, an attempt was made to select L. ferrooxidans from the polymetallic concentrate leachate and further developed it for enhanced ferric iron regeneration from the leachate in shake flask, stirred tank and column reactor. When ferric to ferrous iron ratio in the shake flask reached to 20:1, L. ferrooxidans out competed Acidithiobacillus ferrooxidans and accounted for more than 99% of the total population. The isolate was confirmed by 16S rRNA genes sequence analysis and named as L. ferrooxidans SRPCBL. When the culture was exposure to UV dose and the oxidation-reduction potential of the inoculation medium was adjusted to 40 0mV by ferrous:ferric iron ratio, the IOR reached to as high as 1.2 g/L/h in shake flask, even with initial ferrous iron concentration of 200 g/L. The chalcopyrite concentrate leachate containing 12.8, 15.7, and 42.0 g/L ferrous iron, ferric iron and copper, respectively was studied for ferric iron regeneration with the developed polymetallic resistant L. ferrooxidans SRPCBL in stirred tank and a developed biofilm airlift column, the highest IOR achieved were 2.20 g/L/h and 3.1 g/L/h, respectively, with ferrous oxidation efficiency of 98%. The ferric regeneration ability of the developed isolate from the leachate proves useful for a two-stage metal extraction process. PMID:18325759

Dave, Shailesh R

2008-11-01

185

Ferric Iron Reduction by Acidophilic Heterotrophic Bacteria  

PubMed Central

Fifty mesophilic and five moderately thermophilic strains of acidophilic heterotrophic bacteria were tested for the ability to reduce ferric iron in liquid and solid media under aerobic conditions; about 40% of the mesophiles (but none of the moderate thermophiles) displayed at least some capacity to reduce iron. Both rates and extents of ferric iron reduction were highly strain dependent. No acidophilic heterotroph reduced nitrate or sulfate, and (limited) reduction of manganese(IV) was noted in only one strain (Acidiphilium facilis), an acidophile which did not reduce iron. Insoluble forms of ferric iron, both amorphous and crystalline, were reduced, as well as soluble iron. There was evidence that, in at least some acidophilic heterotrophs, iron reduction was enzymically mediated and that ferric iron could act as a terminal electron acceptor. In anaerobically incubated cultures, bacterial biomass increased with increasing concentrations of ferric but not ferrous iron. Mixed cultures of Thiobacillus ferrooxidans or Leptospirillum ferrooxidans and an acidophilic heterotroph (SJH) produced sequences of iron cycling in ferrous iron-glucose media.

Johnson, D. Barrie; McGinness, Stephen

1991-01-01

186

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

Microsoft Academic Search

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

Liang K. Tan; John E. Dutrizac

1985-01-01

187

Ferric chloride graphite intercalation compounds prepared from graphite fluoride  

NASA Technical Reports Server (NTRS)

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

Hung, Ching-Cheh

1994-01-01

188

21 CFR 73.1025 - Ferric ammonium citrate.  

Code of Federal Regulations, 2013 CFR

...color additive ferric ammonium citrate consists of complex chelates prepared by the interaction of ferric hydroxide with citric acid in the presence of ammonia. The complex chelates occur in brown and green forms, are deliquescent in air, and...

2013-04-01

189

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

190

Spectroscopic studies of swift heavy ion irradiated nanophase mullite  

NASA Astrophysics Data System (ADS)

Photoluminescence (PL) studies of 100 MeV swift Ag 8+ 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 is excited with 326 nm laser beam, three bands with peaks at ˜460, 550 and a well resolved one with peak at 760 nm are observed. It is observed that the PL intensity increases up to 5 × 10 11 ions/cm 2 and thereafter it decreases with increase of ion fluence. The pristine as well as Ag 8+ ion irradiated mullites are characterized by infrared spectroscopy (IR) and X-ray diffraction (XRD) techniques. The decrease in PL intensity is attributed to Al-O and Si-O bonds present as the surface getting amorphized. The effects of Ag 8+ irradiation are compared to those obtained with Ni 8+ ions and the results are discussed.

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

2006-03-01

191

Bioaccumulation of cadmium bound to ferric hydroxide and particulate organic matter by the bivalve M. meretrix.  

PubMed

Ferric hydroxide and particulate organic matter are important pools of trace metals in sediments and control their accumulation by benthic animals. We investigated bioaccumulation of cadmium in bivalve Meretrix meretrix by using a simplified system of laboratory synthesized iron oxides and commercially obtained humic acids to represent the inorganic and organic matrix found in nature. The results showed that bioaccumulation characteristics were distinctly different for these two substrates. Bioaccumulation from ferric hydroxide was not observed at 70 and 140 mg/kg, while the clams started to absorb Cd at 140 mg/kg from organic matter and the bioaccumulation rate was faster than that from ferric hydroxide. Within 28 d, accumulation of Cd from organic matter appeared to reach a steady state after rising to a certain level, while absorption from ferric hydroxide appeared to follow a linear profile. The findings have implications about the assimilation of trace metals from sediments by benthic animals. PMID:22445921

Wu, Xing; Jia, Yongfeng; Zhu, Huijie

2012-06-01

192

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

Microsoft Academic Search

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

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

1997-01-01

193

Preparation of nanophase M-type ferrite and its laser-attenuated characteristics  

NASA Astrophysics Data System (ADS)

By citrate sol-gel auto-combustion method, the nanophase M-type planar hexagonal ferrite is prepared. The transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermal analysis are used to study the grain size, phase composition, microstructure and crystallization process. The results show that the nanophase M-type Sr-ferrite prepared by this method is single, and its grain size is smaller than 100 nm. Moreover, most of the grains present hexagonal sheet shape. Tests are carried out for its attenuation to 1.06 ?m laser. It is found that the extinction capability of the nanophase M-type Sr-ferrite smoke is good, and its mass extinction coefficient is 1.628 m2/g.

Liu, Xiang-Cui; Cheng, Xiang; Zhang, Liang; Liu, Jian-Hui; Du, Gui-Ping

2011-07-01

194

Synthesis of the NiZr 2 intermetallic compound nanophase materials  

NASA Astrophysics Data System (ADS)

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

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

1996-02-01

195

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

2010-12-01

196

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

197

Purification and some properties of sulfur:ferric ion oxidoreductase from Thiobacillus ferrooxidans  

SciTech Connect

A sulfur:ferric ion oxidoreductase that utilizes ferric ion (Fe/sup 3 +/) as an electron acceptor of elemental sulfur was purified from iron-grown Thiobacillus ferrooxidans to an electrophoretically homogeneous state. Under anaerobic conditions in the presence of Fe/sup 3 +/, the enzyme reduced 4 mol of Fe/sup 3 +/ with 1 mol of elemental sulfur to give 4 mol of Fe/sup 2 +/ and 1 mol of sulfite, indicting that it corresponds to a ferric ion-reducing system. Under aerobic conditions, sulfite, but not Fe/sup 2 +/, was produced during the oxidation of elemental sulfur by this enzyme because the Fe/sup 2 +/ produced was rapidly reoxidized chemically by molecular oxygen. The possibility that Fe/sup 3 +/ serves as an electron acceptor under aerobic conditions was ascertained by adding o-phenanthroline, which chelates Fe/sup 2 +/, to the reaction mixture. Sulfur oxidation by this enzyme was absolutely dependent on the presence of reduced glutathione. The enzyme had an isoelectric point and a pH optimum at pH 4.6 and 6.5, respectively. Almost all the activity of sulfur:ferric ion oxidoreductase was observed in the osmotic shock fluid of the cells, suggesting that it was localized in the periplasmic space of the cells.

Sugio, T.; Mizunashi, W.; Inagaki, K.; Tano, T.

1987-11-01

198

Limit of miscibility and nanophase separation in associated mixtures.  

PubMed

We present a detailed analysis of the mixing process in an associating system, the water-tert-butanol (2-methyl-2-propanol) mixture. Using molecular dynamics simulations, together with neutron, X-ray diffraction experiments, and pulsed gradient spin-echo NMR, we study the local structure and dynamic properties over the full concentration range, and thereby provide quantitative data that reveal relationships between local structure and macroscopic behavior. For an alcohol-rich mixture, diffraction patterns from both neutron and X-ray experiments exhibit a peak at low wavelength vector (q ? 0.7 Å(-1)) characteristic of supermolecular structures. On increasing the water content, this "prepeak" progressively flattens and shifts to low wave vector . We identify hydrogen bonds in the system as the driving force for the specific organization that appears in mixtures, and provide an analysis of the variation of the cluster size distribution with composition. We find that the sizes of local hydrogen-bonded clusters observed in alcohol-rich mixtures become larger as the mole fraction, x(w), of water is increased; a nanophase separation is seen for x(w) in the range 0.6-0.7. This corresponds to several changes in some macroscopic properties of the liquid mixture. Thus, we propose a microscopic description of the effect of water addition in alcohol, which is in agreement with both neutron diffraction pattern and mobility of water and alcohol species. In summary we present a full and comprehensive description of miscibility at its limit in an associated system. PMID:23937163

Artola, P A; Raihane, A; Crauste-Thibierge, C; Merlet, D; Emo, M; Alba-Simionesco, C; Rousseau, B

2013-08-22

199

Staining localization of ferric reduction on roots  

Microsoft Academic Search

Tomato plants (cv. ‘Rutgers') were grown in nutrient solutions without and with FeEDDHA or at low phosphorus levels to evaluate the formation of prussian blue (Fe4[Fe(CN)6]3?nH2O), a stain used in determining the site of ferric reduction on roots. The effect of Fe source, Fe concentration, solution pH, and time were evaluated. Prussian blue was compared with nitro?BT, and agar systems

P. F. Bell; R. L. Chaney; J. S. Angle

1988-01-01

200

Desilication from DWPF Recycle using Ferric Flocculation  

SciTech Connect

The presence of silicate and glass-forming frit in the recycle waste from the Defense Waste Processing Facility produces wastes that when combined with the traditional aluminate-bearing wastes stored in H-Tank farm can produce insoluble sodium aluminosilicates. Treatment to remove the silicon has been proposed to allow greater flexibility for processing these wastes in the Site's evaporators. The use of a ferric precipitation (flocculation) to remove the silicon has been tested using waste simulants.

Wilmarth, W.R.

2002-10-24

201

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

National Technical Information Service (NTIS)

The nanophase magnetite crystals in the black rims of pancake-shaped carbonate globules of the Martian meteorite ALH84001 have been studied extensively because of the claim by McKay et al. that they are biogenic in origin. A subpopulation of these magneti...

D. C. Golden D. W. Ming H. V. Lauer R. V. Morris

2006-01-01

202

Optical properties of nanophase films measured by variable-angle spectroscopic ellipsometry  

Microsoft Academic Search

While interest in nanophase films deposited in vacuum from nanoparticle beams dates back to the early 1970s, difficulties in producing such films has delayed their development and investigation of their interesting, new properties predicted. A new type of high-rate deposition system here and at a few other laboratories has overcome these impediments. It is becoming clear that extremely high surface

F. K. Urban; A. Hosseini-Tehrani; A. Khabari; P. Griffiths; C. Bungay; I. Petrov; Y. Kim

2002-01-01

203

Protective Coatings of Nanophase Diamond Prepared by a Laser Plasma Discharge Source  

Microsoft Academic Search

Nanophase diamond films are prepared at room temperature with a laser plasma discharge source without the use of any catalyst. The beam from a pulsed Nd:YAG laser operating with a repetition rate of 10 Hz is focused on graphite in an ultrahigh vacuum chamber. At laser intensities near 5 x 10^{11} W cm ^{-2}, an ablation plasma of multiply charged

1994-01-01

204

EXAFS Study on the Noncrystalline Structure of Binary Component (BiCu, BiTe) Nanophase Particles  

NASA Astrophysics Data System (ADS)

From the viewpoint of the size dependence of the melting point of small particles, the microstructure of nanophase particles is investigated with EXAFS. Two EXAFS spectrum from BiCu and BiTe nanophase particles indicated the specific line shape due to the disorder of atomic structure of the particles, which was not found for corresponding bulk materials. This fact means that a nanophase particle has not only soft surface due to size effect but also a liquid-like inner structure caused by a thermal fluctuation.

Itoh, M.; Tohno, S.; Adachi, M.; Kimura, K.

205

Nanophase Carbonates on Mars: Implications for Carbonate Formation and Habitability  

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

206

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

207

Proximal Ligand Electron Donation and Reactivity of the Cytochrome P450 Ferric-Peroxo Anion  

PubMed Central

CYP125 from Mycobacterium tuberculosis catalyzes sequential oxidation of the cholesterol side-chain terminal methyl group to the alcohol, aldehyde, and finally acid. Here, we demonstrate that CYP125 simultaneously catalyzes the formation of five other products, all of which result from deformylation of the sterol side chain. The aldehyde intermediate is shown to be the precursor of both the conventional acid metabolite and the five deformylation products. The acid arises by protonation of the ferric-peroxo anion species and formation of the ferryl-oxene species, also known as Compound I, followed by hydrogen abstraction and oxygen transfer. The deformylation products arise by addition of the same ferric-peroxo anion to the aldehyde intermediate to give a peroxyhemiacetal that leads to C-C bond cleavage. This bifurcation of the catalytic sequence has allowed us to examine the effect of electron donation by the proximal ligand on the properties of the ferric-peroxo anion. Replacement of the cysteine thiolate iron ligand by a selenocysteine results in UV-vis, EPR, and resonance Raman spectral changes indicative of an increased electron donation from the proximal selenolate ligand to the iron. Analysis of the product distribution in the reaction of the selenocysteine substituted enzyme reveals a gain in the formation of the acid (Compound I pathway) at the expense of deformylation products. These observations are consistent with an increase in the pKa of the ferric-peroxo anion, which favors its protonation and therefore Compound I formation.

Sivaramakrishnan, Santhosh; Ouellet, Hugues; Matsumura, Hirotoshi; Guan, Shenheng; Moenne-Loccoz, Pierre; Burlingame, Alma L.

2012-01-01

208

Proximal ligand electron donation and reactivity of the cytochrome P450 ferric-peroxo anion.  

PubMed

CYP125 from Mycobacterium tuberculosis catalyzes sequential oxidation of the cholesterol side-chain terminal methyl group to the alcohol, aldehyde, and finally acid. Here, we demonstrate that CYP125 simultaneously catalyzes the formation of five other products, all of which result from deformylation of the sterol side chain. The aldehyde intermediate is shown to be the precursor of both the conventional acid metabolite and the five deformylation products. The acid arises by protonation of the ferric-peroxo anion species and formation of the ferryl-oxene species, also known as Compound I, followed by hydrogen abstraction and oxygen transfer. The deformylation products arise by addition of the same ferric-peroxo anion to the aldehyde intermediate to give a peroxyhemiacetal that leads to C-C bond cleavage. This bifurcation of the catalytic sequence has allowed us to examine the effect of electron donation by the proximal ligand on the properties of the ferric-peroxo anion. Replacement of the cysteine thiolate iron ligand by a selenocysteine results in UV-vis, EPR, and resonance Raman spectral changes indicative of an increased electron donation from the proximal selenolate ligand to the iron. Analysis of the product distribution in the reaction of the selenocysteine substituted enzyme reveals a gain in the formation of the acid (Compound I pathway) at the expense of deformylation products. These observations are consistent with an increase in the pK(a) of the ferric-peroxo anion, which favors its protonation and, therefore, Compound I formation. PMID:22444582

Sivaramakrishnan, Santhosh; Ouellet, Hugues; Matsumura, Hirotoshi; Guan, Shenheng; Moënne-Loccoz, Pierre; Burlingame, Alma L; Ortiz de Montellano, Paul R

2012-04-18

209

Catalytic decomposition of hydrogen peroxide by ferric ion in dilute sulfuric acid solutions  

NASA Astrophysics Data System (ADS)

Hydrogen peroxide decomposition in acidic solutions is catalyzed by the free ferric ion, Fe3+. The following rate law for this reaction is determined by the initial rate method in solutions similar to those used for acidic in situ uranium leaching: - (dm_{H_2 O_2 } /dt)_{25^circ C} = k{(m_{H_2 O_2 } )(m_{Fe} 3 - )}/{(m_H - )} where k = 4.3 × 10-3 s°1 at 25 °C. From 25° to 50 °C, the activation energy is 85.6 kJ/mol. The decomposition of hydrogen peroxide proceeds by a particular redox reaction sequence that depends on the ratio of the concentrations of hydrogen peroxide to free ferric ion. The rate law determined here is consistent with the form derived from the redox sequence for the case where the ratio of hydrogen peroxide to free ferric ion concentration is greater than 1.0. The magnitude of the rate constant indicates that the decomposition of hydrogen peroxide may cause rapid loss of this oxidant in leaching solutions containing ferric ion.

Eary, L. E.

1985-06-01

210

Kinetic analysis of the formation and decay of a non-heme ferric hydroperoxide species susceptible to O-O bond homolysis.  

PubMed

The formation of a ferric hydroperoxide species from [Fe(bbpc)(MeCN)2](2+) (bbpc = N,N'-dibenzyl-N,N'-bis(2-pyridylmethyl)-1,2-cyclohexanediamine) and its subsequent decomposition were analyzed kinetically. The rate of decay is not strongly influenced by the presence of either water or substrate, suggesting that the ferric hydroperoxide degrades through O-O bond homolysis and is not the relevant metal-based oxidant in the observed catalysis of C-H activation. The rate law corresponding to the complex's formation from O2 is consistent with the intermediacy of a mononuclear ferric superoxo species. PMID:24783960

Zhang, Qiao; Goldsmith, Christian R

2014-05-19

211

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

212

Ferric iron reduction by Desulfovibrio vulgaris Hildenborough wild type and energy metabolism mutants  

Microsoft Academic Search

Desulfovibrio vulgaris Hildenborough wild type and its hyn1, hyd and hmc mutants, lacking genes for periplasmic [NiFe] hydrogenase-1, periplasmic [FeFe] hydrogenase or the transmembrane high molecular\\u000a weight cytochrome (Hmc) complex, respectively, were able to reduce Fe(III) chelated with nitrilotriacetic acid (NTA), but\\u000a not insoluble ferric oxide, with lactate as the electron donor. The rate and extent of Fe(III)-NTA reduction followed

Hyung Soo Park; Shiping Lin; Gerrit Voordouw

2008-01-01

213

Chemical oxidation kinetics of pyrite in bioleaching processes  

Microsoft Academic Search

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

M Boon; J. J Heijnen

1998-01-01

214

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

215

Shewanella spp. Use acetate as an electron donor for denitrification but not ferric iron or fumarate reduction.  

PubMed

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. PMID:23396327

Yoon, Sukhwan; Sanford, Robert A; Löffler, Frank E

2013-04-01

216

Ferric iron budget of Kaapvaal cratonic mantle peridotite  

NASA Astrophysics Data System (ADS)

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

Woodland, A.

2012-04-01

217

46 CFR 151.50-75 - Ferric chloride solution.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Ferric chloride solution. 151.50-75 Section 151.50-75...Requirements § 151.50-75 Ferric chloride solution. A containment system (cargo tank...system, and gauging system) carrying this solution must be lined with rubber,...

2013-10-01

218

76 FR 17556 - Sodium Ferric Ethylenediaminetetraacetate; Exemption From the Requirement of a Tolerance  

Federal Register 2010, 2011, 2012, 2013

...sodium ferric ethylenediaminetetraacetate (EDTA) in or on all food commodities when applied...permissible level for residues of sodium ferric EDTA under the FFDCA. DATES: This regulation...tolerance for residues of sodium ferric EDTA. This notice referenced a summary...

2011-03-30

219

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

Code of Federal Regulations, 2013 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...

2013-07-01

220

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

221

Phyllosilicates and nanophase aluminosilicates at Mawrth Vallis and their geochemical implications  

NASA Astrophysics Data System (ADS)

Modelling of TES data has shown the presence of allophane in several sites on Mars with the highest abundances in the Mawrth Vallis region [1]. Analyses of CRISM data at Mawrth Vallis are also consistent with the nanophase aluminosilicates allophane and imogolite in the upper Al/Si-rich phyllosilicatebearing unit [2,3]. We report here on recent lab analyses of several allophane and imogolite samples and new analyses of CRISM and TES data enabled with this larger spectral library. Clay-type components are modelled across the Mawrth Vallis region at ~50-75 vol% in bright units and ~35-55 vol% in dark units using TES data. Identification of nanophase aluminosilicates at Mawrth Vallis helps reconcile the NIR and TIR data of the region, and has important implications for understanding past pedogenic and igneous processes.

Bishop, J. L.; Rampe, E.

2013-09-01

222

The leaching of nickeliferous laterite with ferric chloride  

NASA Astrophysics Data System (ADS)

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

Munroe, Norman D. H.

1997-12-01

223

Energy Transduction by Anaerobic Ferric Iron Respiration in Thiobacillus ferrooxidans  

PubMed Central

Formate-grown cells of the obligately chemolithoautotrophic acidophile Thiobacillus ferrooxidans were capable of formate- and elemental sulfur-dependent reduction of ferric iron under anaerobic 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.

1991-01-01

224

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

225

Matrix effects for reflectivity spectra of dispersed nanophase (superparamagnetic) hematite with application to Martian spectral data  

Microsoft Academic Search

The effect of the matrix on the reflectivity spectra of nanophase (superparamagnetic) hematite (np-Hm) dispersed within the matrix was investigated in four series of powder samples containing np-Hm dispersed within discrete powder particles (of two size ranges) of silica gel and activated alumina. The spectral data show that matrix effects are large. Samples with the same Fe2O3 content can have

Richard V. Morris; Howard V. Lauer

1990-01-01

226

Thermal stability and grain growth of a melt-spun HfNi 5 nanophase alloy  

Microsoft Academic Search

A single phase HfNi5 nanocrystalline (NC) sample was prepared by quenching a Hf11 Ni89 alloy with the melt-spinning technique. A randomly oriented HfNi5 nanophase material with an average grain size of about 10 nm was formed in the as-quenched state. Differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and X-ray diffraction (XRD) analysis were used for the investigation of the

K. Lu; Z. F. Dong; I. Bakonyi; Á. Cziraki

1995-01-01

227

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

228

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

229

The crystal chemistry of ferric oxyhydroxyapatite.  

PubMed

Ferric hydroxyapatites (Fe-HAp) and oxyapatites (Fe-OAp) of nominal composition [Ca(10-x)Fe(x)(3+)][(PO(4))(6)][(OH)(2-x)O(x)] (0 < or = x < or = 0.5) were synthesized from a coprecipitated precursor calcined under flowing nitrogen. The solid solubility of iron was temperature-dependent, varying from x = 0.5 after firing at 600 degrees C to x approximately 0.2 at 1000 degrees C, beyond which Fe-OAp was progressively replaced by tricalcium phosphate (Fe-TCP). Crystal size (13-116 nm) was controlled by iron content and calcination temperature. Ferric iron replaces calcium by two altervalent mechanisms in which carbonate and oxygen are incorporated as counterions. At low iron loadings, carbonate predominantly displaces hydroxyl in the apatite channels (Ca(2+) + OH(-) --> Fe(3+) + CO(3)(2-)), while at higher loadings, "interstitial" oxygen is tenanted in the framework (2Ca(2+) + (vac) --> 2Fe(3+) + O(2+)). Although Fe(3+) is smaller than Ca(2+), the unit cell dilates as iron enters apatite, providing evidence of oxygen injection that converts PO(4) tetrahedra to PO(5) trigonal bipyramids, leading to the crystal chemical formula [Ca(10-x)Fe(x)][(PO(4))(6-x/2)(PO(5))(x/2)][(OH)(2-y)O(2y)] (x < or = 0.5). A discontinuity in unit cell expansion at x approximately 0.2 combined with a substantial reduction of the carbonate FTIR fingerprint shows that oxygen infusion, rather than tunnel hydroxyl displacement, is dominant beyond this loading. This behavior is in contrast to ferrous-fluorapatite where Ca(2+) --> Fe(2+) aliovalent replacement does not require oxygen penetration and the cell volume contracts with iron loading. All of the materials were paramagnetic, but at low iron concentrations, a transition arising from crystallographic modification or a change in spin ordering is observed at 90 K. The excipient behavior of Fe-OAp was superior to that of HAp and may be linked to the crystalline component or mediated by a ubiquitous nondiffracting amorphous phase. Fe-HAp and Fe-OAp are not intrinsically suitable magnetic agents for drug delivery but may be useful in reactive cements that promote osteoblast proliferation. PMID:19007209

Low, H R; Phonthammachai, N; Maignan, A; Stewart, G A; Bastow, T J; Ma, L L; White, T J

2008-12-15

230

Immobilization of Arsenite and Ferric Iron by Acidithiobacillus ferrooxidans and Its Relevance to Acid Mine Drainage  

PubMed Central

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.

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

2003-01-01

231

Ferrous-Ferric Ion exchange dosemeter.  

PubMed

In this work a three-dimensional ferrous-ferric ion exchange dosemeter is proposed and the dose response measured. The dosemeter consists of strong acid cation exchange resin beads in the H form in water. Amberlyst 15 Wet beads with a harmonic mean diameter of 0.600-0.850 mm were prepared by soaking them in an aqueous solution of ferrous ammonium sulphate to exchange ferrous ions for H(+) ions. The beads were rinsed with distilled water and packed in glass vials. Sets of samples with ferrous ion concentrations of 0.5 and 1.0 mM were dosed with 6 MV X rays from a Varian 2100C linac. The spin-lattice relaxation time constants (T1) for the samples were measured using an Apollo spectrometer (Tecmag, Houston, TX) interfaced to a 1.5 T magnet (Magnex, Abingdon, UK). Each sample had two T1 values; a long T1 at 1200 ms that did not significantly change with dose and a short T1 that ranged from 56 ms at 0 Gy to 36 ms at 100 Gy. The R1 vs. dose responses were linear with slopes of 0.066 and 0.079 s(-1) Gy(-1). PMID:16644977

Bauhs, John A; Hammer, Bruce E

2006-01-01

232

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

233

Oxidation of iron powder in a fluidized bed reactor  

Microsoft Academic Search

The potential and technological viability of oxidation of iron powder for the production of high purity ferric oxide for soft ferrites have been discussed. Results of cold model studies have been incorporated. It has been shown that the conversion of iron powder to ferric oxide is a function of particle size, time and temperature of fluidization. The optimum properties have

M. G. Bodas; D. R. Dash; C. S. Sivaramakrishnan

1996-01-01

234

21 CFR 184.1296 - Ferric ammonium citrate.  

Code of Federal Regulations, 2013 CFR

...reaction of ferric hydroxide with citric acid, followed by treatment with...percent ammonia, and 65 percent citric acid and occurs as reddish brown or...percent ammonia, and 75 percent citric acid and occurs as thin...

2013-04-01

235

EXTRACTION WITH TRIBUTYL PHOSPHATE (TBP) FROM FERRIC NITRATE SOLUTIONS  

Microsoft Academic Search

Ferric nitrate acts as a strong salting-out agent in the extraction of thorium(IV), uranyl, europium(III), samarium(III) and zirconium(IV) nitrates as well as of nitric acid with tributyl phosphate in dodecane. Nitric acid, if present in the extraction system together with large amounts of ferric nitrate, markedly suppresses the extraction of thorium(IV) and lanthanides(III) but significantly supports the extraction of zirconium(IV).

Z. Kolarik; K. Grudpan

1985-01-01

236

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

2012-06-01

237

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

238

Kinetics of iron acquisition from ferric siderophores by Paracoccus denitrificans.  

PubMed Central

The kinetics of iron accumulation by iron-starved Paracoccus denitrificans during the first 2 min of exposure to 55Fe-labeled ferric siderophore chelates is described. Iron is acquired from the ferric chelate of the natural siderophore L-parabactin in a process exhibiting biphastic kinetics by Lineweaver-Burk analysis. The kinetic data for 1 microM less than [Fe L-parabactin] less than 10 microM fit a regression line which suggests a low-affinity system (Km = 3.9 +/- 1.2 microM, Vmax = 494 pg-atoms of 55Fe min-1 mg of protein-1), whereas the data for 0.1 microM less than or equal to [Fe L-parabactin] less than or equal to 1 microM fit another line consistent with a high-affinity system (Km = 0.24 +/- 0.06 microM, Vmax = 108 pg-atoms of 55Fe min-1 mg of protein-1). The Km of the high-affinity uptake is comparable to the binding affinity we had previously reported for the purified ferric L-parabactin receptor protein in the outer membrane. In marked contrast, ferric D-parabactin data fit a single regression line corresponding to a simple Michaelis-Menten process with comparatively low affinity (Km = 3.1 +/- 0.9 microM, Vmax = 125 pg-atoms of 55Fe min-1 mg of protein-1). Other catecholamide siderophores with an intact oxazoline ring derived from L-threonine (L-homoparabactin, L-agrobactin, and L-vibriobactin) also exhibit biphasic kinetics with a high-affinity component similar to ferric L-parabactin. Circular dichroism confirmed that these ferric chelates, like ferric L-parabactin, exist as the lambda enantiomers. The A forms ferric parabactin (ferrin D- and L-parabactin A), in which the oxazoline ring is hydrolyzed to the open-chain threonyl structure, exhibit linear kinetics with a comparatively high Km (1.4 +/- 0.3 microM) and high Vmax (324 pg-atoms of 55Fe min-1 of protein-1). Furthermore, the marked stereospecificity seen between ferric D- and L-parabactins is absent; i.e., iron acquisition from ferric parabactin A is non stereospecific. The mechanistic implications of these findings in relation to a stereospecific high-affinity binding followed by a nonstereospecific postreceptor processing is discussed.

Bergeron, R J; Weimar, W R

1990-01-01

239

A novel, kinetically stable, catalytically active, all-ferric, nitrite-bound complex of Paracoccus pantotrophus cytochrome cd1.  

PubMed

The oxidized form of Paracoccus pantotrophus cytochrome cd(1) nitrite reductase, as isolated, has bis-histidinyl co-ordination of the c haem and His/Tyr co-ordination of the d(1) haem. On reduction, the haem co-ordinations change to His/Met and His/vacant respectively. If the latter form of the enzyme is reoxidized, a conformer is generated in which the ferric c haem is His/Met co-ordinated; this can revert to the 'as isolated' state of the enzyme over approx. 20 min at room temperature. However, addition of nitrite to the enzyme after a cycle of reduction and reoxidation produces a kinetically stable, all-ferric complex with nitrite bound to the d(1) haem and His/Met co-ordination of the c haem. This complex is catalytically active with the physiological electron donor protein pseudoazurin. The effective dissociation constant for nitrite is 2 mM. Evidence is presented that d(1) haem is optimized to bind nitrite, as opposed to other anions that are commonly good ligands to ferric haem. The all-ferric nitrite bound state of the enzyme could not be generated stoichiometrically by mixing nitrite with the 'as isolated' conformer of cytochrome cd(1) without redox cycling. PMID:12086580

Allen, James W A; Higham, Christopher W; Zajicek, Richard S; Watmough, Nicholas J; Ferguson, Stuart J

2002-09-15

240

A novel, kinetically stable, catalytically active, all-ferric, nitrite-bound complex of Paracoccus pantotrophus cytochrome cd1.  

PubMed Central

The oxidized form of Paracoccus pantotrophus cytochrome cd(1) nitrite reductase, as isolated, has bis-histidinyl co-ordination of the c haem and His/Tyr co-ordination of the d(1) haem. On reduction, the haem co-ordinations change to His/Met and His/vacant respectively. If the latter form of the enzyme is reoxidized, a conformer is generated in which the ferric c haem is His/Met co-ordinated; this can revert to the 'as isolated' state of the enzyme over approx. 20 min at room temperature. However, addition of nitrite to the enzyme after a cycle of reduction and reoxidation produces a kinetically stable, all-ferric complex with nitrite bound to the d(1) haem and His/Met co-ordination of the c haem. This complex is catalytically active with the physiological electron donor protein pseudoazurin. The effective dissociation constant for nitrite is 2 mM. Evidence is presented that d(1) haem is optimized to bind nitrite, as opposed to other anions that are commonly good ligands to ferric haem. The all-ferric nitrite bound state of the enzyme could not be generated stoichiometrically by mixing nitrite with the 'as isolated' conformer of cytochrome cd(1) without redox cycling.

Allen, James W A; Higham, Christopher W; Zajicek, Richard S; Watmough, Nicholas J; Ferguson, Stuart J

2002-01-01

241

Formation of Metallic Nanophases in Polymeric Matrices for Space Applications  

NASA Technical Reports Server (NTRS)

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

Orwoll, Robert A.; Thompson, David W.

1999-01-01

242

Nanoporous thin films from nanophase-separated hybrids of block copolymer/metal salt  

NASA Astrophysics Data System (ADS)

Block copolymers self-assemble into periodic nanostructures, i.e. nanophase-separated structures, which can be scaffolds for nano-applications such as nanoporous membranes, nanolithographic masks, photonic crystals, etc. In this study, we report facile preparation to achieve nanoporous thin films from nanophase-separated hybrids comprising polystyrene-b-poly(4-vinylpyridine) (PS-P4VP, Mn=54k, PDI=1.13, fs=0.61) and water-soluble iron(III) chloride (FeCl3), where FeCl3 are incorporated into a P4VP phase via metal-to-ligand coordination. To obtain a nanoporous film, firstly a hybrid thin film was prepared by microtoming. Then, the film was immersed into water to remove metal salts, this simple procedure can produce nanoporous thin film. Morphological observations were conducted by using transmission electron microscopy (TEM). Ordered cylindrical nanopores were observed in the thin film of the water-immersed hybrid, which originally presents cylindrical nanodomains. The nanoporous film was modified by loading another metal salt, samarium(III) nitrate, into nanopores via coordination between the metal salt and P4VP tethered to the pore walls. The structure of the sample after modification was evaluated by TEM and an energy dispersive X-ray spectroscopy.

Sageshima, Yoshio; Noro, Atsushi; Matsushita, Yushu

2013-03-01

243

Laboratory Simulation of Space Weathering: ESR Measurements of Nanophase Metallic Iron in Laser-irradiated Olivine and Pyroxene Samples  

NASA Technical Reports Server (NTRS)

S-type asteroids are believed to be parent bodies of ordinary chondrites. Although both S-type asteroids and ordinary chondrites contain the same mineral assemblage, mainly olivine and pyroxene, the reflectance spectra of the asteroids exhibit more overall depletion (darkening) and reddening, and more weakening of absorption bands relative to the meteorites. This spectral mismatch is explained by space weathering process, where high-velocity dust particle impacts should change the optical properties of the uppermost regolith surface of asteroids. In order to simulate the space weathering, we irradiated nanosecond pulse laser beam onto pellet samples of olivine (8.97wt% FeO) and pyroxene (enstatite: 9.88wt% FeO, hypersthene: 16.70wt%). We got spectral changes in our samples similar to that by space weathering on asteroids and confirmed nanophase alpha-metallic iron particles, which were theoretically predicted, not only on olivine but also on pyroxene samples by Transmission Electron Microscopy (TEM). Nanophase metallic iron particles were widely scattered throughout the amorphous rims developed along the olivine grains, whereas they were embedded in aggregates of amorphous in enstatite samples. Recently, we also measured laser-irradiated samples by ESR (Electron Spin Resonance). Strong ESR signals, characteristic to nanophase iron particles, are observed on irradiated olivine samples. In this paper, we report the quantities of nanophase metallic iron particles in pyroxene samples by ESR observations in addition to olivine samples.

Kurahashi, E.; Yamanaka, C.; Nakamura, K.; Sasaki, S.

2003-01-01

244

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

National Technical Information Service (NTIS)

X-ray diffraction (XRD) data collected of the Rocknest samples by the CheMin instrument on Mars Science Laboratory suggest the presence of poorly crystalline or amorphous materials (1), such as nanophase weathering products or volcanic and impact glasses....

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

2013-01-01

245

Arsenic removal by iron-doped activated carbons prepared by ferric chloride forced hydrolysis.  

PubMed

Ferric chloride forced hydrolysis is shown to be a good method for increasing the iron content of activated carbons (ACs). Iron content increased linearly with hydrolysis time, and ACs with iron content as high as 9.4wt.% at 24h hydrolysis time could be prepared. The increase in iron content did not produce any modification in the textural parameters determined by nitrogen adsorption at 77K. Iron-based nanoparticles, homogeneous in size and well-dispersed in the carbon matrix, were obtained. Nanoparticles forming iron (hydr)oxide agglomerates at the outer surface of the carbon grains at hydrolysis times higher than 6h were also produced. The AC obtained after 6h of ferric chloride forced hydrolysis removed 94% of the arsenic present in a groundwater from the State of Chihuahua (Mexico), whereas the commercial AC used as precursor allowed the removal of only 14%. The lower performance in arsenic removal observed for AC prepared using long forced hydrolysis time (24h) is probably due to the existence of iron (hydr)oxides nanoparticles agglomerates, which once hydrated could prevent diffusion of arsenate (HAsO(4)(-)) towards the inner surface of the AC grain. PMID:19349116

Fierro, V; Muñiz, G; Gonzalez-Sánchez, G; Ballinas, M L; Celzard, A

2009-08-30

246

Construction techniques for adiabatic demagnetization refrigerators using ferric ammonium alum  

NASA Astrophysics Data System (ADS)

We describe techniques used to fabricate the cold stage of an adiabatic demagnetization refrigerator that uses the paramagnetic salt ferric ammonium alum. We discuss the design of a leak-tight housing for the salt as well as a technique for growing ferric ammonium alum crystals that results in a housing filled with >98% refrigerant. These techniques have proven to be reliable in creating robust single-stage refrigerators. Similar techniques can be used for the second stage of a dual-stage adiabatic demagnetization refrigerator.

Wilson, Grant W.; Timbie, Peter T.

1999-07-01

247

An investigation of the thermodynamics and kinetics of the ferric chloride brine leaching of galena concentrate  

NASA Astrophysics Data System (ADS)

The solution thermodynamics of acidified ferric chloride brine lixiviants and the dissolution kinetics of a galena concentrate in such solutions have been investigated. The distribution of the various metal chloro complexes calculated from available thermodynamic data shows that the distribution is shifted to the higher complexes, predominantly FeCl{3/o}, FeCl{2/o}, and PbCl{4/=}, as the total Cl- concentration increases, and that the distribution is unaffected by the extent of reaction. The dissolution of PbS concentrate is presented as a competition between a nonoxidative reaction with H+ and the oxidative reaction with ferric ion. Acid dissolution of PbS predominates when the activity ratio of hydrogen ion to ferric ion is high. Under these conditions H2S is produced. When the activity ratio of hydrogen ion to ferric ion is low, and especially when the concentration of Fe3+ is greater than 0.15 M, oxidative dissolution of PbS becomes the controlling reaction. The dissolution can be represented by a shrinking core model with a surface chemical reaction as the rate controlling step. This is supported by the activation energy of 72.1 kJ/mole and the dependence of the rate on the inverse of the particle radius. The following rate equation was found to be in excellent agreement with the experimentally observed leaching behavior for 0.15 to 0.6 M [Fe+3] T up to approximately 90 to 95 pet extraction: 11663_2007_Article_BF02670816_TeX2GIFE1.gif 1 - left( {1 - ? } right)^{1/3} = left[ {{2.3 x 10^{12} }/{r_0 }left[ {{text{Fe}}^{{text{ + 3}}} } right]_T^{0.21} exp left( {{ - 72100}/{{text{R}T}}} right)} right]t The rate deviates from the 0.21 order for Fe+3 concentrations greater than 0.6 M. The deviation from the surface model at higher values of PbS conversion is due to the presence of solid PbCl2 in the pores of the reacting particles.

Kim, Seon-Hyo; Henein, H.; Warren, G. W.

1986-01-01

248

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

SciTech Connect

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

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

1980-12-01

249

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

2013-10-01

250

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

251

Dehydration of Mars Relevant Ferric Sulfates at High Temperatures Studied by Laser Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

We explored the dehydration of Mars relevant ferric sulfates using laser Raman spectroscopy, which provides important clue to uncover the mystery of relatively rarely detected ferric sulfates on martian surface by orbital remote sensing.

Liu, Y.; Wang, A.

2014-06-01

252

The FRE1 ferric reductase of Saccharomyces cerevisiae is a cytochrome b similar to that of NADPH oxidase.  

PubMed

Plasma membrane preparations from strains of the yeast Saccharomyces cerevisiae gave a reduced minus oxidized spectrum characteristic of a b-type cytochrome and very similar to the spectrum of flavocytochrome b558 of human neutrophils. The magnitude of the signal correlated with the level of ferric reductase activity and the copy number of the FRE1 gene, indicating that the FRE1 protein is a cytochrome b. Sequence similarities with the flavin binding site of flavocytochrome b558 and other members of the ferredoxin-NADP reductase family, together with increased levels of noncovalently bound FAD and iodonitrotetrazolium violet reductase activity in membranes from a yeast strain overexpressing ferric reductase, suggested that the FRE1 protein may also carry a flavin group. Potentiometric titrations indicated that FRE1, like neutrophil NADPH oxidase, has an unusually low redox potential, in the region of -250 mV, and binds CO. PMID:8662973

Shatwell, K P; Dancis, A; Cross, A R; Klausner, R D; Segal, A W

1996-06-14

253

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

254

Hydroperoxide Assay with the Ferric–Xylenol Orange Complex  

Microsoft Academic Search

A range of hydroperoxides were reduced by ferrous ions in acid solutions and the amount of ferric product was measured as a xylenol orange complex at 560 nm. Dilute sulfuric acid, 50% acetic acid, and acidified 90% methanol proved to be suitable solvents. The color developed within 15 min and was stable for several hours in most solvents. The apparent

Craig Gay; James Collins; Janusz M. Gebicki

1999-01-01

255

Fullerenyl boronic esters: ferric perchlorate-mediated synthesis and functionalization.  

PubMed

Fullerenyl boronic esters have been prepared by a ferric perchlorate-promoted reaction of [60]fullerene with various arylboronic acids. The obtained fullerenyl boronic esters could undergo further functionalization with diols to afford C(60)-fused dioxane/dioxepane derivatives. A possible reaction mechanism for the formation of fullerenyl boronic esters has been proposed. PMID:22416858

Li, Fa-Bao; You, Xun; Liu, Tong-Xin; Wang, Guan-Wu

2012-04-01

256

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

257

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

SciTech Connect

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

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

2005-01-31

258

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

259

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

260

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

261

Organic matter mineralization with the reduction of ferric iron: A review  

Microsoft Academic Search

A review of the literature indicates that numerous microorganisms can reduce ferric iron during the metabolism of organic matter. In most cases, the reduction of ferric iron appears to be enzymatically catalyzed and, in some instances, may be coupled to an electron transport chain that could generate ATP. However, the physiology and biochemistry of ferric iron reduction are poorly understood.

Derek R. Lovley

1987-01-01

262

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

PubMed Central

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

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

2005-01-01

263

Attenuation of Hydrogen Peroxide and Ferric Reducing/Antioxidant Power Serum Levels in Colorectal Cancer Patients with Intestinal Parasitic Infection  

PubMed Central

Background: This study assessed several common oxidative indices in subjects infected with intestinal parasites, as well as in colorectal cancer (CRC) patients both with and without intestinal parasites. Method: Serum levels of malondialdehyde (MDA), ferric reducing/antioxidant power (FRAP), and hydrogen peroxide (H2O2) were measured, as were plasma levels of advanced oxidation protein products (AOPP), all according to established methods. The presence of intestinal parasites was confirmed by stool examination. Results: All intestinal parasiteinfected subjects and CRC patients showed the presence of oxidative stress. Thirtysix percent of the CRC patients had intestinal parasitic infections. The levels of H2O2 and FRAP in parasite-infected subjects were significantly higher than in CRC patients, but these levels were significantly lower in the CRC patients with parasitic infections. Conclusion: Parasitic infection and CRC may contribute to oxidative stress independently, but when present together, the oxidative stress burden imposed by parasites may be attenuated.

Chandramathi, Samudi; Suresh, Kumar Govind; Anita, Zarina Bustam; Kuppusamy, Umah Rani

2009-01-01

264

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

SciTech Connect

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

Burgos, W. D.

2005-02-01

265

Structural Characterization of Ferric Hemoglobins from Three Antarctic Fish Species of the Suborder Notothenioidei  

PubMed Central

Spontaneous autoxidation of tetrameric Hbs leads to the formation of Fe (III) forms, whose physiological role is not fully understood. Here we report structural characterization by EPR of the oxidized states of tetrameric Hbs isolated from the Antarctic fish species Trematomus bernacchii, Trematomus newnesi, and Gymnodraco acuticeps, as well as the x-ray crystal structure of oxidized Trematomus bernacchii Hb, redetermined at high resolution. The oxidation of these Hbs leads to formation of states that were not usually detected in previous analyses of tetrameric Hbs. In addition to the commonly found aquo-met and hydroxy-met species, EPR analyses show that two distinct hemichromes coexist at physiological pH, referred to as hemichromes I and II, respectively. Together with the high-resolution crystal structure (1.5 Å) of T. bernacchii and a survey of data available for other heme proteins, hemichrome I was assigned by x-ray crystallography and by EPR as a bis-His complex with a distorted geometry, whereas hemichrome II is a less constrained (cytochrome b5-like) bis-His complex. In four of the five Antartic fish Hbs examined, hemichrome I is the major form. EPR shows that for HbCTn, the amount of hemichrome I is substantially reduced. In addition, the concomitant presence of a penta-coordinated high-spin Fe (III) species, to our knowledge never reported before for a wild-type tetrameric Hb, was detected. A molecular modeling investigation demonstrates that the presence of the bulkier Ile in position 67? in HbCTn in place of Val as in the other four Hbs impairs the formation of hemichrome I, thus favoring the formation of the ferric penta-coordinated species. Altogether the data show that ferric states commonly associated with monomeric and dimeric Hbs are also found in tetrameric Hbs.

Vergara, Alessandro; Franzese, Marisa; Merlino, Antonello; Vitagliano, Luigi; Verde, Cinzia; di Prisco, Guido; Lee, H. Caroline; Peisach, Jack; Mazzarella, Lelio

2007-01-01

266

Ferric saponite and serpentine in the nakhlite martian meteorites  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

267

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

268

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

PubMed Central

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 55Fe radiolabeled ferric citrate and that a protein, BC_3466 [renamed FctC (ferric citrate-binding protein C)], binds ferric citrate. The dissociation constant (Kd) 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.

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

2012-01-01

269

Thermal stability and grain growth of a melt-spun HfNi{sub 5} nanophase alloy  

SciTech Connect

A single phase HfNi{sub 5} nanocrystalline (NC) sample was prepared by quenching a Hf{sub 11}Ni{sub 89} alloy with the melt-spinning technique. A randomly oriented HfNi{sub 5} nanophase material with an average grain size of about 10 nm was formed in the as-quenched state. Differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and X-ray diffraction (XRD) analysis were used for the investigation of the thermal stability and grain growth of the NC HfNi{sub 5} sample. On heating the NC sample at a constant heating rate, two exothermal peaks appear in the DSC curve, corresponding to a grain-growth process of the HfNi{sub 5} nanophase prior to a precipitation process of Ni solid solution. It was found the grain-growth temperature of the NC HfNi{sub 5} phase is approximately equal to the crystallization temperature of the same compositional amorphous alloy. The average grain boundary energy in the NC sample calculated by means of the calorimetric results, is about 0.36 J/m{sup 2}. Activation energies for the grain growth and Ni precipitation are calculated by using the Kissinger equation. It was obtained that the value of the activation energy for the HfNi{sub 5} nanophase grain growth is close to that for the volume self-diffusion in Hf. The grain growth mechanism and the thermal stability of the NC material are also discussed.

Lu, K.; Dong, Z.F. [Academia Sinica, Shenyang (China)] [Academia Sinica, Shenyang (China); Bakonyi, I. [Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Solid State Physics] [Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Solid State Physics; Cziraki, A. [Eoetvoes Univ., Budapest (Hungary). Inst. for Solid State Physics] [Eoetvoes Univ., Budapest (Hungary). Inst. for Solid State Physics

1995-07-01

270

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

2012-12-18

271

Quantitative determination of cesium binding to ferric hexacyanoferrate: Prussian blue  

Microsoft Academic Search

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

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

2008-01-01

272

Sodium ferric gluconate complex maintenance therapy in children on hemodialysis  

Microsoft Academic Search

Intravenous iron therapy is recommended for children and adults who receive hemodialysis (HD) and recombinant human erythropoietin\\u000a (rHuEPO). However, limited information exists on the use of any maintenance IV iron regimen in children. Therefore, we conducted\\u000a a prospective, multicenter, open-label trial of maintenance therapy with sodium ferric gluconate complex (SFGC) in iron-replete\\u000a pediatric HD patients receiving rHuEPO. Patients received SFGC

Bradley A. Warady; R. Howard Zobrist; Eileen Finan

2006-01-01

273

Supramolecular Ferric Porphyrins as Cyanide Receptors in Aqueous Solution  

PubMed Central

All fundamental data about binding of the cyanide to a supramolecular complex composed of a per-O-methylated ?-cyclodextrin dimer having an imidazole linker (Im3CD) and an anionic ferric porphyrin (Fe(III)TPPS) indicate that the Fe(III)TPPS/Im3CD complex is much better as an cyanide receptor in vivo than hydroxocobalamin, whose cyanide binding ability is lowered by its strong binding to serum proteins in the blood.

2011-01-01

274

Supramolecular ferric porphyrins as cyanide receptors in aqueous solution.  

PubMed

All fundamental data about binding of the cyanide to a supramolecular complex composed of a per-O-methylated ?-cyclodextrin dimer having an imidazole linker (Im3CD) and an anionic ferric porphyrin (Fe((III))TPPS) indicate that the Fe((III))TPPS/Im3CD complex is much better as an cyanide receptor in vivo than hydroxocobalamin, whose cyanide binding ability is lowered by its strong binding to serum proteins in the blood. PMID:24900285

Watanabe, Kenji; Kitagishi, Hiroaki; Kano, Koji

2011-12-01

275

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

276

Reaction mechanism for the acid ferric sulfate leaching of chalcopyrite  

Microsoft Academic Search

The acid ferric sulfate leaching of chalcopyrite, CuFeS2 + 4Fe+3 = Cu+2 + 5Fe+2 + 2S0 was studied using monosize particles in a well stirred reactor at ambient pressure and dilute solid phase concentration in\\u000a order to obtain fundamental details of the reaction kinetics. The principal rate limiting step for this electrochemical reaction\\u000a appears to be a transport process through

P. B. Munoz; J. D. Miller; M. E. Wadsworth

1979-01-01

277

The dissolution of sphalerite in ferric sulfate media  

Microsoft Academic Search

The dissolution of sphalerite, (Zn,Fe)S, in ferric sulfate media was investigated using closely sized fractions of crushed sphalerite crystals. Linear kinetics were observed, and the rate increased in proportion to the surface area, as the average particle size of the sphalerite decreased. The predominant reaction products are ZnSO4, FeSO4, and elemental sulfur. The leaching rate increases with increasing temperature, and

J. E. Dutrizac

2006-01-01

278

The dissolution of sphalerite in ferric sulfate media  

Microsoft Academic Search

The dissolution of sphalerite, (Zn,Fe)S, in ferric sulfate media was investigated using closely sized fractions of crushed\\u000a sphalerite crystals. Linear kinetics were observed, and the rate increased in proportion to the surface area, as the average\\u000a particle size of the sphalerite decreased. The predominant reaction products are ZnSO4, FeSO4, and elemental sulfur. The leaching rate increases with increasing temperature, and

J. E. Dutrizac

2006-01-01

279

Complexation of Nicotinamide Adenine Dinucleotide with Ferric and Ferrous Ions  

Microsoft Academic Search

Motivated by the observed influence of stainless steel and ferric and ferrous ions on the behavior of the peroxidase\\/oxidase oscillator, the mechanism and kinetics of interaction of 1,4-dihydronicotinamide adenine dinucleotide (NADH) with iron ions in 0.1 M acetic acid\\/sodium acetate buffer with pH 5.1 and with the solution\\/stainless steel interface were extensively studied. The character of a possible mutual influence

V. Lvovich; A. Scheeline

1995-01-01

280

Synthesis, characterization, and bioavailability in rats of ferric phosphate nanoparticles  

Microsoft Academic Search

Particle size is a determinant of iron (Fe) absorption from poorly soluble Fe compounds. Decreasing the particle size of metallic Fe and ferric pyrophosphate added to foods increases Fe absorption. The aim of this study was to develop and characterize nanoparticles of FePO4 and determine their bioavailability and potential toxicity in rats. Amorphous FePO4 nanopowders with spherical structure were synthesized

Fabian Rohner; Frank O. Ernst; Myrtha Arnold; Monika Hilbe; Ralf Biebinger; Frank Ehrensperger; Sotiris E. Pratsinis; Wolfgang Langhans; Richard F. Hurrell; Michael B. Zimmermann

2007-01-01

281

Reactive Absorption of Hydrogen Sulfide in Aqueous Ferric Sulfate Solution  

Microsoft Academic Search

Many commercial processes are available for the removal of H2S from gaseous streams. The desulfurization of gas streams using aqueous ferric sulfate solution as washing liquor is studied. Apart from sulfur, only H2O is generated in the process, and consequently, no waste treatment facilities are required. A distinct advantage of the process is that the reaction of H2S with is

Z. Gholami; M. Torabi Angaji; F. Gholami; S. A. Razavi Alavi

2009-01-01

282

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

283

Factors influencing the mechanism of surfactant catalyzed reaction of vitamin C-ferric chloride hexahydrate system  

NASA Astrophysics Data System (ADS)

The kinetics of vitamin C by ferric chloride hexahydrate has been investigated in the aqueous ethanol solution of basic surfactant viz. octadecylamine (ODA) under pseudo-first order conditions. The critical micelle concentration (CMC) of surfactant was determined by surface tension measurement. The effect of pH (2.5-4.5) and temperature (15-35°C) in the presence and absence of surfactant were investigated. Activation parameters, ? E a, ? H #, ? S #, ? G ?, for the reaction were calculated by using Arrhenius and Eyring plot. Surface excess concentration (?max), minimum area per surfactant molecule ( A min), average area occupied by each molecule of surfactant ( a), surface pressure at the CMC (?max), Gibb's energy of micellization (? G M°), Gibb's energy of adsorption (? G ad°), were calculated. It was found that the reaction in the presence of surfactant showed faster oxidation rate than the aqueous ethanol solution. Reaction mechanism has been deduced in the presence and absence of surfactant.

Farrukh, Muhammad Akhyar; Kauser, Robina; Adnan, Rohana

2013-09-01

284

Measurement of lipid hydroperoxides by the ferric-xylenol orange method (2) application to lipoxygenase assay.  

PubMed

The ferric-xylenol orange (FOX) method has been used for quantification of hydroperoxides by measuring the colored ferric-xylenol orange (XO/Fe3+) product with a peak absorbance at 560 nm. We recently reported a modified FOX method, the sensitivity of which was increased in the presence of membranous phosphatidylcholine (PC) by forming a XO/Fe3+-PC complex with a peak absorbance at 610 nm. Lipoxygenases (LOXs) and their metabolites have been implicated in a wide range of disease states. We applied our newly developed FOX method to the assay of human 15-lipoxygenase-2 (15-LOX-2) and soybean lipoxygenase (SLOX) as typical animal and plant lipoxygenases, respectively. The amounts of 15-S-hydroperoxyeicosa-5,8,10,14-tetraenoic acid (15-HPETE) produced by 15-LOX-2 measured by UV-absorption at 237 nm attributed to the conjugated diene, coincided with the results of our FOX method measuring absorbance at 610 nm. The 15-HPETE production time courses measured by the two methods also correlated well. SLOX rapidly oxidized unesterified linoleic acids (LA) and slowly esterified fatty acids in egg yolk PC (EYPC). Availability of EYPC was increased if the membrane structure was moderately disturbed by MeOH and Triton X-100, but LA oxidation was readily decreased by them. These results indicate that our method is useful for lipoxygenase assay. Furthermore, our method was applicable to assaying the inhibitory effect of 5,8,11,14-eicosatetraynoic acid (ETYA) on SLOX activity using LA and EYPC as substrates. The inhibition dose-dependency of ETYA was almost the same in the LA and EYPC systems, although the enzyme concentrations differed by a factor of 1,000, suggesting that ETYA functioned as a competitive inhibitor. These results indicate that our method may be useful as a screen for the identification of novel inhibitors of lipoxygenases. PMID:19352069

Fukuzawa, Kenji; Sano, Masumi; Akai, Kaori; Morishige, Junichi; Tokumura, Akira; Jisaka, Mitsuo

2009-02-01

285

Bioavailability of iron from ferric choline citrate and a ferric copper cobalt choline citrate complex for young pigs.  

PubMed

Two experiments were conducted to determine the bioavailability for young pigs of Fe from ferric choline citrate or from a commercial mixture of Fe, Cu and Co choline citrate salts. Relative biological value of Fe from either source with a standard of 100 for FeSO4 x 7H20 was about 140 by both hemoglobin regeneration and Fe retention methods. PMID:7263536

Miller, E R; Parsons, M J; Ullrey, D E; Ku, P K

1981-04-01

286

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

287

Soft chemical synthesis and characterization of lithium nickel oxide electrode materials  

Microsoft Academic Search

Soft chemistry was used to prepare ordered nanophase Li0.6NiO2 electrode materials by completing the oxidation of Ni2+ to Ni3+ and\\/or Ni4+ species with H2O2 oxidant during solution reactions at 50–60 °C and evaporation at 105–150 °C rather than during sintering. Both elemental analysis and electron spectroscopy for chemical analysis (ESCA) results indicate that oxidation was completed. The deconvoluted ESCA spectra

X. Xiao; Y. Xu

1996-01-01

288

[The upconversion luminescence of Tm(0.35)Yb(5):FOV nanophase oxyfluoride vitroceramics].  

PubMed

The upconversion luminescence of nanophase oxyfluoride vitroceramics Tm(0.35)Yb(5) : FOV when excited by a 975 nm diode laser was studied in the present paper. Several ultraviolet upconversion luminescence lines positioned at 363.6 nm, (462.6 nm, 477.0 nm), 648.7 nm, (699.7 nm, 680.7 nm) and (777.6 nm, 800.7 nm) were found. They can be attributed to the fluorescence transitions of 1 D2-->3 H6, 1 G4-->3 H6, 1 G4-->3 F4, 3 F3-->3 H6 and 3 H4-->3 H6 of Tm3+ ion. The careful measurement and analysis of the variation of upconversion luminescence intensity F as a function of the 975 nm pumping laser power P has proven that the upconversion luminescence of 1 D2 state is partly a five-photon upconversion luminescence, while the upconversion luminescence of 1 G4 and 3 H4 state is the three-photon and two-photon upconversion luminescence respectively. PMID:18975790

Chen, Xiao-bo; Wang, Ya-fei; Sawanobori, Naruhito; Yang, Guo-jian; Cui, Jian-sheng; He, Chen-juan; Chen, Zhi-jian; Liu, Da-he; Peng, Fang-lin; Song, Zeng-fu

2008-08-01

289

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

PubMed

Quasi-one-dimensional YSi(2) 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. PMID:23221350

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

2013-01-01

290

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

SciTech Connect

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 structure of four solutions as a function of w (the molar ratio of [water]/[AOT]) is characterized by small-angle neutron scattering at room temperature. With the addition of ZrOCl{sub 2} and NH{sub 4}OH into the water pools, the reverse micelle sizes decrease as compared to those in the D{sub 2}O/AOT/C{sub 6}D{sub 5}CD{sub 3} primary system. The mixed microemulsions contain reverse micelle sizes that fail between the values of the pre-mixed solutions. All the reverse micelles exhibit uniform size and spherical shape. The effect of concentration of inorganic salt precursor in the water pools on the reverse micelle structure is also studied.

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

1999-07-02

291

Structure and Growth of Quasi One-Dimensional YSi2 Nanophases on Si(100)  

PubMed Central

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. In addition to previously identified stoichiometric wires, we identify 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 microcopy 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 by 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

292

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

293

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

PubMed

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

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

2014-07-01

294

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

PubMed

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

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

2014-01-01

295

Development of Leptospirillum ferriphilum dominated consortium for ferric iron regeneration and metal bioleaching under extreme stresses.  

PubMed

Activated iron oxidizing consortium SR-BH-L enriched from Rajpardi lignite mine soil sample gave iron oxidation rate 1954 mg/L/h. Developed novel polystress resistant consortium oxidized ferrous iron under 11cP viscosity, 7.47 M ionic strength, 2.3 pH and g/L of 0.50 cadmium, 3.75 copper, 0.20 lead, 92.00 zinc, 6.4 sodium, 5.5 chloride, 154 sulphate and 393.8 TDS. The developed consortium showed 78.0% and 70.0% copper and zinc extraction from polymetallic bulk concentrate in monophasic bioleaching process. The bioregenerated ferric by the consortium in leachate showed 80.81% and 54.0% copper and zinc leaching in only 30 and 90 min. The DGGE analysis indicated the presence of 11 OTUs in the consortium. 16S rRNA gene sequence (JN797729) of the dominant band on DGGE shared >99% similarity with Leptospirillum ferriphilum. RE digestion analysis of the total 16S rRNA gene also illustrated the dominance of L. ferriphilum in the consortium. PMID:22717567

Patel, Bhargav C; Tipre, Devayani R; Dave, Shailesh R

2012-08-01

296

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

PubMed Central

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

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

2014-01-01

297

Formation of 8-oxo-2?-deoxyguanosine in the DNA of human diploid fibroblasts by treatment with linoleic acid hydroperoxide and ferric ion  

Microsoft Academic Search

Lipid peroxides are suggested to be related to the occurrence of a variety of diseases including cancer and atherosclerosis.\\u000a We examined whether lipid peroxides cause oxidative damage to DNA in intact cells. Linoleic acid hydroperoxide (LOOH) and\\u000a ferric chloride were used at concentrations at which separate treatment had no effect on the formation of 8-oxo-2?-deoxyguanosine\\u000a (8-oxodG) in DNA or the

Takao Kaneko; Shoichi Tahara

2000-01-01

298

Magnetic, Electronic, and Structural Properties of Ferric Chloride Intercalated Graphite.  

NASA Astrophysics Data System (ADS)

The magnetic, electronic, and structural properties of intercalated graphite compounds in general, and ferric chloride intercalated graphite compounds in particular, are examined by various experimental and theoretical techniques. Both a microscopic experiment, Mossbauer spectroscopy, and a macroscopic experiment, magnetic susceptibility, indicate that stage 1 and 2 compounds undergo a long-range magnetic phase transition, while evidence is found that stage 4 and 6 compounds do not magnetically order down to 65mK. The magnetic transition temperature dramatically decreases as more diamagnetic graphite planes are added. Therefore, we conclude that the ordering mechanism is influenced by interlayer interactions thus providing direct evidence that magnetic ordering in these compounds is a three-dimensional effect. By using Mossbauer spectroscopy as a characterization tool, we find a sample dependent number of iron vacancies, which dramatically influences the susceptibility curves of the samples. Thus these two experiments also help elucidate the role of iron vacancies in disturbing long-range order thus causing some of the iron spins to acquire spin-glass like characteristics. The electronic properties of these compounds are also examined by Mossbauer spectroscopy. Below 100K donated electrons from the graphite lattice are localized on some ferric chloride sites to change these iron sites from ferric to ferrous sites. The Mossbauer data indicate that at low temperatures the ferric and ferrous sites are not randomly situated, and may form a unique chemical superlattice. The localization process is studied by Mossbauer spectroscopy and two possible explanations of the data are presented. We also examine the role of iron vacancies on the acceptor site. We find that chlorine atoms surrounding iron vacancies, when present in sufficient number, may act as the primary acceptor site for the electrons donated by the graphite to the intercalant. The effects of long-term exposure to air on these compounds is also studied by Mossbauer spectroscopy. A simple model of staging in graphite intercalation compounds is presented which yields only the staged structures which are observed experimentally. We show that for some intercalants, no other structures should be observed while providing physical guidelines for identifying materials in which more complex structures may be realized.

Millman, Steven Edward

299

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

300

Pre-Terrestrial Oxidation Products in Carbonaceous Meteorites Identified by Mossbauer Spectroscopy.  

National Technical Information Service (NTIS)

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...

R. G. Burns D. S. Fisher

1991-01-01

301

Functional characterization of the chloroplast ferric chelate oxidoreductase enzyme.  

PubMed

Iron (Fe) has an essential role in the biosynthesis of chlorophylls and redox cofactors, and thus chloroplast iron uptake is a process of special importance. The chloroplast ferric chelate oxidoreductase (cFRO) has a crucial role in this process but it is poorly characterized. To study the localization and mechanism of action of cFRO, sugar beet (Beta vulgaris cv Orbis) chloroplast envelope fractions were isolated by gradient ultracentrifugation, and their purity was tested by western blotting against different marker proteins. The ferric chelate reductase (FCR) activity of envelope fractions was studied in the presence of NAD(P)H (reductants) and FAD coenzymes. Reduction of Fe(III)-ethylenediaminetetraacetic acid was monitored spectrophotometrically by the Fe(II)-bathophenanthroline disulfonate complex formation. FCR activity, that is production of free Fe(II) for Fe uptake, showed biphasic saturation kinetics, and was clearly associated only to chloroplast inner envelope (cIE) vesicles. The reaction rate was > 2.5 times higher with NADPH than with NADH, which indicates the natural coenzyme preference of cFRO activity and its dependence on photosynthesis. FCR activity of cIE vesicles isolated from Fe-deficient plants also showed clear biphasic kinetics, where the KM of the low affinity component was elevated, and thus this component was down-regulated. PMID:24506824

Solti, Adám; Müller, Brigitta; Czech, Viktória; Sárvári, Éva; Fodor, Ferenc

2014-05-01

302

Ion flotation and solvent extraction of ferric thiocyanate complexes  

SciTech Connect

The influence of thiocyanate and accompanying mineral acids concentration on the effectiveness of Fe(III) ion flotation, Fe(III) precipitation in cetyltrimethylammonium ferric-thiocyanate form (as sublate), and Fe(III) extraction using ethyl acetate was studied. The effectiveness of these processes improves with the extent of Fe(III) complexation by thiocyanates. In the presence of acids, flotation and precipitation are increased as follows: HClO/sub 4/ < HCl < HNO/sub 3/ < H/sub 2/SO/sub 4/. The position of H/sub 3/PO/sub 4/ in this series changes with changing thiocyanate concentration. Extraction effectiveness is increased in the series: H/sub 3/PO/sub 4/ < H/sub 2/SO/sub 4/ < HNO/sub 3/, HClO/sub 4/, HCl. The following points are discussed: (a) the influence of acid anions competing with thiocyanate anions in Fe(III) complexation; (b) the influence of the competition between acid anions and complex ferric-thiocyanate anions in sublate formation; (c) the influence of hydrogen ion concentration increase in thiocyanate medium on the results of Fe(III) flotation, precipitation, and extraction; and (d) the influence of anion affinity for a collector on the solution surface properties and on Fe(III) flotation.

Jurkiewicz, K.

1987-12-01

303

Microstructural, mechanical, and osteocompatibility properties of Mg2+/F(-)-doped nanophase hydroxyapatite.  

PubMed

Pure as well as Mg(2+)- and F(-)-doped nanophase (i.e., grain sizes in the nanometer regime in at least one dimension) hydroxyapatite (HA) samples were synthesized by a precipitation method followed by sintering at 1100 degrees C for 1 h to determine their microstructural, mechanical, and osteoblast (bone-forming cell) adhesion properties pertinent for orthopedic applications. Different amounts of Mg(2+) and F(-) ions (specifically from 0 to 7.5 mol %) were doped into the HA samples. X-ray diffraction was used to identify the presence of crystalline phases, lattice parameters, and crystal volumes of the samples. Fourier transform infrared (FTIR) was further used to chemically characterize HA, and thus FTIR patterns revealed the characteristic absorption bands of HA. Microhardness measurements were also performed to assess mechanical properties of the novel formulations. Results of this study showed an improvement in sample density for some of the samples, which was a consequence of the molar percentage variation of the dopants. Moreover, in most of the samples doped with Mg, beta-tricalcium phosphate was observed as a second phase to HA. In addition, 1% Mg- and 2.5% F-doped HA had the highest microhardness values. Lastly, results demonstrated the highest osteoblast densities when the HA samples were doped with 2.5-7.5% Mg(2+) and F(-). Thus, the results of this study suggest that decreasing the grain size of HA into the nanometer regime and doping HA with Mg(2+) and F(-) can potentially increase the efficacy of HA for orthopedic applications. PMID:20336758

Sun, Zehra Pinar; Ercan, Batur; Evis, Zafer; Webster, Thomas J

2010-09-01

304

Heterophase mechanisms of thermal oxidation of polymers. New horizons  

NASA Astrophysics Data System (ADS)

Based on the results of kinetic analysis of numerous experimental data, advantages of heterogeneous and heterophase mechanisms of autooxidation of non-crystalline polymers over homogeneous liquid-phase mechanisms are demonstrated. The supermolecular organisation of polymer chains according to the pattern of spongy micelles incorporating non-uniform porous areas is chosen as the model structure. It is established that, depending on the physical state of the polymer, the oxidation kinetics correspond either to a mechanism in which reaction chains are distributed over non-uniform nanophases or to a mechanism in which they are mainly located in one nanophase. The kinetic equations obtained for the macroscopic stages of oxidation take into account the dependence of the chemical reactivity of reactants on the thermomechanical mobility of the molecular sponge. It is demonstrated that the fine structure of molecular spongy micelles plays a crucial role in the chemical physics of polymers. The bibliography includes 94 references.

Mikheev, Yurii A.; Zaikov, Gennadii E.

2000-03-01

305

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

306

Biogeochemical Properties of Bacteriogenic Iron Oxides  

Microsoft Academic Search

Bacteriogenic iron oxides (BIOS) are composite materials that consist of intact and partly degraded remains of bacterial cells intermixed with variable amounts of poorly ordered hydrous ferric oxide (HFO) minerals. They form in response to chemical or bacterial oxidation of Fe, which gives rise to Fe. Once formed, Fe tends to undergo hydrolysis to precipitate in association with bacterial cells.

F. G. Ferris

2005-01-01

307

Modeling ferrous–ferric iron chemistry with application to martian surface geochemistry  

Microsoft Academic Search

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

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

2008-01-01

308

Sodium ferric gluconate complex in hemodialysis patients: Adverse reactions compared to placebo and iron dextran  

Microsoft Academic Search

Sodium ferric gluconate complex in hemodialysis patients: Adverse reactions compared to placebo and iron dextran.BackgroundParenteral iron is often required by hemodialysis patients to maintain adequate iron stores. Until recently, the only available form of intravenous iron was iron dextran, which is associated with significant adverse reactions, including anaphylaxis and death. Sodium ferric gluconate complex (SFGC) was recently approved for use

Beckie Michael; Daniel W. Coyne; Steven Fishbane; Vaughn Folkert; Robert Lynn; Allen R. Nissenson; Rajiv Agarwal; Joseph W. Eschbach; Stephen Z. Fadem; J. Richard Trout; Jur Strobos; David G. Warnock

2002-01-01

309

Suppression of Stainless Steel Corrosion in CAN-DECON Decontamination with Ferric Complexes.  

National Technical Information Service (NTIS)

Laboratory scale CAN-DECON decontamination tests were conducted with both low and high concentrations of ferric complexes. Increasing ferric complex concentrations from 15 mg/kg to 110 mg/kg resulted in about two orders of magnitude reduction in corrosion...

J. Torok R. L. Tapping B. J. Barry R. D. Davidson

1985-01-01

310

Modeling the early stages of self-assembly in nanophase materials. II. Role of symmetry and dimensionality  

NASA Astrophysics Data System (ADS)

We study the early stages of self-assembly of elementary building blocks of nanophase materials, considering explicitly their structure and the symmetry and the dimensionality of the reaction space. Previous work [Kozak et al., J. Chem. Phys. 134, 154701 (2007)] focused on characterizing self-assembly on small square-planar templates. Here we consider larger lattices of square-planar symmetry having N = 255 sites, and both hexagonal and triangular lattices of N = 256 sites. Furthermore, to assess the consequences of a depletion zone above a basal layer (? = 1), we study self-assembly on an augmented diffusion space defined by ? = 2 and ? = 5 stacked layers having the same characteristics as the basal plane. The effective decrease in the efficiency of self-assembly of individual nanophase units when the diffusion space is expanded, by increasing the template size and/or by enlarging the depletion zone, is then quantified. The results obtained reinforce our earlier conclusion that the most significant factor influencing the kinetics of formation of a final self-assembled unit is the number of reaction pathways from one or more precursor states. We draw attention to the relevance of these results to zeolite synthesis and reactions within pillared clays.

Kozak, John J.; Nicolis, G.

2011-02-01

311

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

312

Niobium Uptake and Release by Bacterial Ferric Ion Binding Protein  

PubMed Central

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

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

2010-01-01

313

Synchrotron Characterization of Hydrogen and Ferric Iron in Martian Meteorites  

NASA Technical Reports Server (NTRS)

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

Dyar, Melinda D.

2003-01-01

314

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

315

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

SciTech Connect

A partial equilibrium model has been developed and used to characterize the conditions under which precipitation of ferric ion occurs during the dump leaching of chalcopyrite ores. The precipitates considered include amorphous Fe(OH)/sub 3/, ..cap alpha..-FeOOH (goethite), and Na/sup +/, K/sup +/, Ag/sup +/, Pb/sup 2 +/, and H/sub 3/O/sup +/ jarosites. The concentration product for Fe(OH)/sub 3/ (am) and ..cap alpha..-FeOOH was calculated for changing solution concentrations and compared with the solubility product constants to determine when precipitation would be expected thermodynamically. The K/sup +/, Na/sup +/, Ag/sup +/, and Pb/sup 2 +/ concentrations necessary to satisfy the solubility product constants were calculated for initial concentrations and varying amounts of O/sub 2/ consumption.

Liddell, K.C.; Bautista, R.G.

1983-03-01

316

Biogenic catalysis of soil formation on Mars?  

PubMed

The high iron abundance and the weak ferric iron spectral features of martian surface material are consistent with nanophase (nm-sized) iron oxide minerals as a major source of iron in the bright region soil on Mars. Nanophase iron oxide minerals, such as ferrihydrite and schwertmannite, and nanophase forms of hematite and goethite are formed by both biotic and abiotic processes on Earth. The presence of these minerals on Mars does not indicate biological activity on Mars, but it does raise the possibility. This work includes speculation regarding the possibility of biogenic soils on Mars based on previous observations and analyses. A remote sensing goal of upcoming missions should be to determine if nanophase iron oxide minerals, clay silicates and carbonates are present in the martian surface material. These minerals are important indicators for exobiology and their presence on Mars would invoke a need for further investigation and sample return from these sites. PMID:9742725

Bishop, J L

1998-10-01

317

Biogenic catalysis of soil formation on Mars?  

NASA Technical Reports Server (NTRS)

The high iron abundance and the weak ferric iron spectral features of martian surface material are consistent with nanophase (nm-sized) iron oxide minerals as a major source of iron in the bright region soil on Mars. Nanophase iron oxide minerals, such as ferrihydrite and schwertmannite, and nanophase forms of hematite and goethite are formed by both biotic and abiotic processes on Earth. The presence of these minerals on Mars does not indicate biological activity on Mars, but it does raise the possibility. This work includes speculation regarding the possibility of biogenic soils on Mars based on previous observations and analyses. A remote sensing goal of upcoming missions should be to determine if nanophase iron oxide minerals, clay silicates and carbonates are present in the martian surface material. These minerals are important indicators for exobiology and their presence on Mars would invoke a need for further investigation and sample return from these sites.

Bishop, J. L.

1998-01-01

318

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

PubMed Central

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

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

2014-01-01

319

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

PubMed

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

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

2014-06-01

320

Degradation of the Ferric Chelate of EDTA by a Pure Culture of an Agrobacterium sp  

PubMed Central

A pure culture of an Agrobacterium sp. (deposited as ATCC 55002) that mineralizes the ferric chelate of EDTA (ferric-EDTA) was isolated by selective enrichment from a treatment facility receiving industrial waste containing ferric-EDTA. The isolate grew on ferric-EDTA as the sole carbon source at concentrations exceeding 100 mM. As the degradation proceeded, carbon dioxide, ammonia, and an unidentified metabolite(s) were produced; the pH increased, and iron was precipitated from solution. The maximum rate of degradation observed with sodium ferric-EDTA as the substrate was 24 mM/day. At a substrate concentration of 35 mM, 90% of the substrate was degraded in 3 days and 70% of the associated chemical oxygen demand was removed from solution. Less than 15% of the carbon initially present was incorporated into the cell mass. Significant growth of this strain was not observed with uncomplexed EDTA as the sole carbon source at comparable concentrations; however, the ferric chelate of propylenediaminetetraacetic acid (ferric-PDTA) did support growth.

Lauff, John J.; Steele, D. Bernie; Coogan, Louise A.; Breitfeller, James M.

1990-01-01

321

Degradation of the ferric chelate of EDTA by a pure culture of an Agrobacterium sp  

SciTech Connect

A pure culture of an Agrobacterium sp. (deposited as ATCC 55002) the mineralizes the ferric chelate of EDTA (ferric-EDTA) was isolated by selective enrichment from a treatment facility receiving industrial waste containing ferric-EDTA. The isolated grew on ferric-EDTA as the sole carbon source at concentrations exceeding 100 mM. As the degradation proceeded, carbon dioxide, ammonia, and an unidentified metabolite(s) were produced; the pH increased, and iron was precipitated from solution. The maximum rate of degradation observed with sodium ferric-EDTA as the substrate was 24 mM/day. At a substrate concentration of 35 mM, 90% of the substrate was degraded in 3 days and 70% of the associated chemical oxygen demand was removed from solution. Less than 15% of the carbon initially present was incorporated into the cell mass. Significant growth of this strain was not observed with uncomplexed EDTA as the sole carbon source at comparable concentrations; however, the ferric chelate of propylenediaminetetraacetic acid (ferric-PDTA) did support growth.

Lauff, J.J.; Coogan, L.A.; Breitfeller, J.M. (Genencor International, Rochester, NY (USA)); Steele, D.B. (Auburn Univ., AL (USA))

1990-11-01

322

[Characteristic of natural organic matter removal by ferric and aluminium coagulation].  

PubMed

Natural organic matter removal efficiency and characteristic by ferric chloride and aluminium sulphate were studied. Results showed that ferric chloride was effective in natural organic matter removal when coagulant dosage was higher than 15 mg/L, while aluminium was effective at lower dosage. The TOC of water was reduced to 4.19 mg/L and 9 mg/L at a dosage of 10 mg/L for aluminium sulphate and ferric chloride respectively, while TOC was reduced to 2.44 mg/L and 1.69 mg/L at the dosage of 20 mg/L. Ferric chloride decreased pH sharply than aluminium sulphate which made hydrolysate more positive and attachable for natural organic matter. UV254 and SUVA results showed that ferric chloride removed more conjugate structure materials and unsaturated band contents than aluminium. Ferric chloride was more effective in reducing lower molecular weight organic matter and hydrophilic substances than aluminium, when the dosage of coagulant was 20 mg/L, the removal efficiency of relative molecular weight below 10 000 was 16.4% and 6.1% respectively, while aluminum was more effective in high molecular weight matter removal than ferric chloride. PMID:18624177

Zhou, Ling-Ling; Zhang, Yong-Ji; Sun, Li-Hua; Li, Gui-Bai

2008-05-01

323

Ferric citrate decreases ruminal hydrogen sulphide concentrations in feedlot cattle fed diets high in sulphate.  

PubMed

Dissimilatory reduction of sulphate by sulphate-reducing bacteria in the rumen produces sulphide, which can lead to a build-up of the toxic gas hydrogen sulphide (H2S) in the rumen when increased concentrations of sulphate are consumed by ruminants. We hypothesised that adding ferric Fe would competitively inhibit ruminal sulphate reduction. The effects of five concentrations and two sources (ferric citrate or ferric ammonium citrate) of ferric Fe were examined in vitro (n 6 per treatment). Rumen fluid was collected from a steer that was adapted to a high-concentrate, high-sulphate diet (0·51 % S). The addition of either source of ferric Fe decreased (P< 0·01) H2S concentrations without affecting gas production (P= 0·38), fluid pH (P= 0·80) or in vitro DM digestibility (P= 0·38) after a 24 h incubation. An in vivo experiment was conducted using eight ruminally fistulated steers (543 (sem 12) kg) in a replicated Latin square with four periods and four treatments. The treatments included a high-concentrate, high-sulphate control diet (0·46 % S) or the control diet plus ferric ammonium citrate at concentrations of 200, 300 or 400 mg Fe/kg diet DM. The inclusion of ferric Fe did not affect DM intake (P= 0·21). There was a linear (P< 0·01) decrease in the concentration of ruminal H2S as the addition of ferric Fe concentrations increased. Ferric citrate appears to be an effective way to decrease ruminal H2S concentrations, which could allow producers to safely increase the inclusion of ethanol co-products. PMID:23880397

Drewnoski, Mary E; Doane, Perry; Hansen, Stephanie L

2014-01-28

324

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

NASA Astrophysics Data System (ADS)

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

Jaén, Juan A.; Navarro, César

2009-07-01

325

Purification and some properties of sulfite:ferric ion oxidoreductase from Thiobacillus ferrooxidans.  

PubMed Central

Sulfite:ferric ion oxidoreductase in the plasma membrane of Thiobacillus ferrooxidans AP19-3 was purified to an electrophoretically homogeneous state. The enzyme had an apparent molecular weight of 650,000 and was composed of two subunits (M(rs), 61,000 and 59,000) as estimated by sodium sulfate-polyacrylamide gel electrophoresis. The Michaelis constants of sulfite:ferric ion oxidoreductase for Fe3+ and sulfite ions were 1.0 and 0.071 mM, respectively. Sulfite:ferric ion oxidoreductase suffered from end product inhibition by 1 mM Fe2+. Images

Sugio, T; Hirose, T; Ye, L Z; Tano, T

1992-01-01

326

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

USGS Publications Warehouse

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

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

1997-01-01

327

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

PubMed

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

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

2014-01-01

328

Rapid photooxidation of As(III) through surface complexation with nascent colloidal ferric hydroxide.  

PubMed

Contamination of water and soils with arsenic, especially inorganic arsenic, has been one of the most important topics in the fields of environmental science and technology. The interactions between iron and arsenic play a very significant role in the environmental behavior and effect of arsenic species. However, the mechanism of As(III) oxidation in the presence of iron has remained unclear because of the complicated speciation of iron and arsenic. Photooxidation of As(III) on nascent colloidal ferric hydroxide (CFH) in aqueous solutions at pH 6 was studied to reveal the transformation mechanism of arsenic species. Experiments were done by irradiation using light-emitting diodes with a central wavelength of 394 nm. Results show that photooxidation of As(III) and photoreduction of Fe(III) occurred simultaneously under oxic or anoxic conditions. Photooxidation of As(III) in the presence of nascent CFH occurred through electron transfer from As(III) to Fe(III) induced by absorption of radiation into a ligand-to-metal charge-transfer (LMCT) band. The estimated quantum yield of photooxidation of As(III) at 394 nm was (1.023 ± 0.065) × 10(-2). Sunlight-induced photooxidation of As(III) also occurred, implying that photolysis of the CFH-As(III) surface complex could be an important process in environments wherein nascent CFH exists. PMID:24313653

Xu, Jing; Li, Jinjun; Wu, Feng; Zhang, You

2014-01-01

329

Ferric Uptake Regulator-Dependent Antinitrosative Defenses in Salmonella enterica Serovar Typhimurium Pathogenesis  

PubMed Central

Herein we report an important role for the ferric uptake regulator (Fur) in the resistance of Salmonella enterica serovar Typhimurium to the reactive nitrogen species produced by inducible nitric oxide (NO) synthase in an NRAMP1r murine model of acute systemic infection. The expression of fur protected Salmonella grown under normoxic and hypoxic conditions against the bacteriostatic activity of NO. The hypersusceptibility of fur-deficient Salmonella to the cytotoxic actions of NO coincides with a marked repression of respiratory activity and the reduced ability of the bacteria to detoxify NO. A fur mutant Salmonella strain contained reduced levels of the terminal quinol oxidases of the electron transport chain. Addition of the heme precursor ?-aminolevulinic acid restored the cytochrome content, respiratory activity, NO consumption, and wild-type growth in bacteria undergoing nitrosative stress. The innate antinitrosative defenses regulated by Fur added to the adaptive response associated with the NO-detoxifying activity of the flavohemoprotein Hmp. Our investigations indicate that, in addition to playing a critical role in iron homeostasis, Fur is an important antinitrosative determinant of Salmonella pathogenesis.

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

2014-01-01

330

Redox potential measurements and Mössbauer spectrometry of Fe II adsorbed onto Fe III (oxyhydr)oxides  

Microsoft Academic Search

The redox properties of FeII adsorbed onto a series of FeIII (oxyhydr)oxides (goethite, lepidocrocite, nano-sized ferric oxide hydrate (nano-FOH), and hydrous ferric oxide (HFO)) have been investigated by rest potential measurements at a platinum electrode, as a function of pH (?log10[H+]) and surface coverage. Using the constant capacitance surface complexation model to describe FeII adsorption onto these substrates, theoretical values

Ewen Silvester; Laurent Charlet; Christophe Tournassat; Antoine Géhin; Jean-Marc Grenèche; Emmanuelle Liger

2005-01-01

331

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

332

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

333

Exfoliation of Hexagonal Boron Nitride via Ferric Chloride Intercalation  

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

334

Monoclonal Antibodies to Ferric Pseudobactin, the Siderophore of Plant Growth-Promoting Pseudomonas putida B10  

PubMed Central

Monoclonal antibodies to ferric pseudobactin, the siderophore (microbial iron transport agent) of plant growth-promoting Pseudomonas putida B10, have been developed. Three immunoglobulin G subclass 1-type monoclonal antibodies have been characterized. Each antibody appears to be unique on the basis of their reactions with ferric pseudobactin and with culture supernatants from other pseudomonads. None of the three cross-reacts with ferric pseudobactin-type siderophores produced by seven other pseudomonads. However, P. aeruginosa ATCC 15692 and P. fluorescens ATCC 17400 produced relatively high-molecular-mass compounds (mass greater than approximately 30,000 daltons) that did react with the antibodies. The compound from P. aeruginosa was not iron regulated, while the compound from P. fluorescens was produced only under iron-limiting conditions. A competitive assay using these antibodies has a detection limit of 5 × 10?12 mol of ferric pseudobactin. This is, to our knowledge, the first report of monoclonal antibodies reactive with siderophores.

Buyer, Jeffrey S.; Sikora, Lawrence J.; Kratzke, Marian G.

1990-01-01

335

Monoclonal Antibodies to Ferric Pseudobactin, the Siderophore of Plant Growth-Promoting Pseudomonas putida B10.  

PubMed

Monoclonal antibodies to ferric pseudobactin, the siderophore (microbial iron transport agent) of plant growth-promoting Pseudomonas putida B10, have been developed. Three immunoglobulin G subclass 1-type monoclonal antibodies have been characterized. Each antibody appears to be unique on the basis of their reactions with ferric pseudobactin and with culture supernatants from other pseudomonads. None of the three cross-reacts with ferric pseudobactin-type siderophores produced by seven other pseudomonads. However, P. aeruginosa ATCC 15692 and P. fluorescens ATCC 17400 produced relatively high-molecular-mass compounds (mass greater than approximately 30,000 daltons) that did react with the antibodies. The compound from P. aeruginosa was not iron regulated, while the compound from P. fluorescens was produced only under iron-limiting conditions. A competitive assay using these antibodies has a detection limit of 5 x 10 mol of ferric pseudobactin. This is, to our knowledge, the first report of monoclonal antibodies reactive with siderophores. PMID:16348116

Buyer, J S; Sikora, L J; Kratzke, M G

1990-02-01

336

Sodium ferric gluconate therapy in renal transplant and renal failure patients  

Microsoft Academic Search

Intravenous infusion of sodium ferric gluconate (Ferrlecit) has been reported to be effective and safe in pediatric and adult\\u000a hemodialysis patients with iron depletion. We sought to expand on the previous studies by treating 13 consecutive pediatric\\u000a renal failure and renal transplant patients with sodium ferric gluconate doses that were higher than previously reported.\\u000a Efficacy was defined as: (1) an

Peter D. Yorgin; Amir Belson; Minnie Sarwal; Steven R. Alexander

2000-01-01

337

Determination of antioxidant capacities of vegetable oils by ferric-ion spectrophotometric methods  

Microsoft Academic Search

Two ferric-ion-based total antioxidant capacity methods: 1,10-phenanthroline (Phen) and ferric reducing antioxidant power (FRAP) were used for determination of antioxidant capacities (AC) of the acetonic and methanolic extracts of vegetable oils. The obtained mean Phen and FRAP values for acetonic extracts of olive oils, rapeseed, rice and four sunflower oils (39.3–336.5 and 39.5–339.6?mol Fe\\/100g) were higher than for methanolic extracts

Aleksandra Szyd?owska-Czerniak; Csilla Dianoczki; Katalin Recseg; György Karlovits; Edward Sz?yk

2008-01-01

338

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

339

Arsenic removal from high-arsenic water by enhanced coagulation with ferric ions and coarse calcite  

Microsoft Academic Search

Arsenic removal from high-arsenic water in a mine drainage system has been studied through an enhanced coagulation process with ferric ions and coarse calcite (38–74?m) in this work. The experimental results have shown that arsenic-borne coagulates produced by coagulation with ferric ions alone were very fine, so micro-filtration (membrane as filter medium) was needed to remove the coagulates from water.

S. Song; A. Lopez-Valdivieso; D. J. Hernandez-Campos; C. Peng; M. G. Monroy-Fernandez; I. Razo-Soto

2006-01-01

340

Determination of arsenic removal efficiency by ferric ions using response surface methodology  

Microsoft Academic Search

Arsenic contamination of drinking water is a serious problem in many parts of the world. The precipitation\\/coprecipitation method was used for arsenic removal from drinking water by ferric chloride, ferric sulfate and ferrous sulfate as coagulant. A Box–Behnken statistical experiment design method was used to investigate the effects of major operating variables such as initial arsenate concentration (10–1000?gL?1), coagulant dose

Meltem Bilici Baskan; Aysegul Pala

2009-01-01

341

Ferric ion, ferrocyanide, and inorganic phosphate as cytochemical reactants at peripheral nodes of Ranvier  

Microsoft Academic Search

Summary Ferric ion (Fe3+) and ferrocyanide (Fe(CN)64-) were used under a variety of conditions to stain nodes of Ranvier in mammalian peripheral nerves. Principal findings are:1.Ferric ion will bind to the extracellular nodal gap substance if nerves are pretreated with a phosphate buffer; or, it will bind to the cytoplasmic surface of the nodal axolemma if pretreatment is with cacodylate

Donald C. Quick; STEPHEN G. WAXMANt

1977-01-01

342

Method for preventing the precipitation of ferric compounds during the acid treatment of wells  

SciTech Connect

A method is described for preventing the undesirable formation and precipitation of ferric compounds from a spent threatment acid containing dissolved iron following an acidizing treatment of subterranean formations surrounding a wellbore. The method consists of adding to the treatment acid prior to contact with the formation an amount of ascorbic acid and/or erythorbic acid, and/or a soluble salt of the acid, sufficient to prevent the formation and precipitation of ferric compounds from the treatment acid upon spending.

Crowe, C.W.; Maddin, C.M.

1986-03-04

343

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

344

Ferric Reduction Is a Potential Iron Acquisition Mechanism for Histoplasma capsulatum  

PubMed Central

For the fungus Histoplasma capsulatum, and for other microbial pathogens, iron is an essential nutrient. Iron sequestration in response to infection is a demonstrated host defense mechanism; thus, iron acquisition may be considered an important pathogenic determinant. H. capsulatum is known to secrete Fe(III)-binding hydroxamate siderophores, which is one common microbial process for acquiring iron. Here, we report H. capsulatum ferric reduction activities in whole yeast cells and in both high- and low-molecular-weight fractions of culture supernatants. Each of these activities was induced or derepressed by growth under iron-limiting conditions, a phenomenon often associated with specific iron acquisition mechanisms. The high-molecular-weight culture supernatant activity was enhanced by the addition of reduced glutathione, was proteinase K sensitive and heat labile, and could utilize ferric chloride, ferric citrate, and human holotransferrin as substrates. The low-molecular-weight culture supernatant activity was resistant to proteinase K digestion. These results are consistent with the expression by H. capsulatum of both enzymatic ferric reductase and nonproteinaceous ferric reductant, both of which are regulated by iron availability. Such components could be involved in fungal acquisition of iron from inorganic or organic ferric salts, from H. capsulatum hydroxamate siderophores, or from host Fe(III)-binding proteins, such as transferrin.

Timmerman, Michelle M.; Woods, Jon P.

1999-01-01

345

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

346

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

PubMed

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

Ansari, Azaj; Kaushik, Abhishek; Rajaraman, Gopalan

2013-03-20

347

Microphase separation in polybenzoxazine thermosets containing benzoxazine-terminated poly(ethylene oxide) telechelics  

Microsoft Academic Search

Benzoxazine-terminated poly(ethylene oxide) telechelics (Ba-terminated PEO) was synthesized and incorporated into polybenzoxazine to obtain the nanostructured thermosets. The morphology of the thermosets was investigated by means of atomic force microscopy (AFM), small angle X-ray scattering (SAXS) and dynamic mechanical analysis (DMA). The formation of the nanophase structures in the thermosetting composites was addressed on the basis of the mechanism of

Yan Li; Chongyin Zhang; Sixun Zheng

2011-01-01

348

Liposome as a Delivery System for Carotenoids: Comparative Antioxidant Activity of Carotenoids As Measured by Ferric Reducing Antioxidant Power, DPPH Assay and Lipid Peroxidation.  

PubMed

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

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

2014-07-16

349

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

350

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

351

The removal of hydrogen sulfide in solution by ferric and alum water treatment residuals.  

PubMed

This work investigated the characteristics and mechanisms of hydrogen sulfide adsorption by ferric and alum water treatment residuals (FARs) in solution. The results indicated that FARs had a high hydrogen sulfide adsorption capacity. pH 7 rather than higher pH (e.g. pH 8-10) was favorable for hydrogen sulfide removal. The Yan model fitted the breakthrough curves better than the Thomas model under varied pH values and concentrations. The Brunauer-Emmett-Teller surface area and the total pore volume of the FARs decreased after the adsorption of hydrogen sulfide. In particular, the volume of pores with a radius of 3-5 nm decreased, while the volume of pores with a radius of 2 nm increased. Therefore, it was inferred that new adsorption sites were generated during the adsorption process. The pH of the FARs increased greatly after adsorption. Moreover, differential scanning calorimetry analysis indicated that elemental sulfur was present in the FARs, while the derivative thermal gravimetry curves indicated the presence of sulfuric acid and sulfurous acid. These results indicated that both oxidization and ligand exchange contribute to the removal of hydrogen sulfide by FARs. Under anaerobic conditions, the maximum amount of hydrogen sulfide released was approximately 0.026 mg g(-1), which was less than 0.19% of the total amount adsorbed by the FARs. The hydrogen sulfide that was released may be re-adsorbed by the FARs and transformed into more stable mineral forms. Therefore, FARs are an excellent adsorbent for hydrogen sulfide. PMID:22520971

Wang, Changhui; Pei, Yuansheng

2012-08-01

352

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

PubMed

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

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

2013-12-31

353

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

PubMed Central

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

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

2014-01-01

354

Folding process of silk fibroin induced by ferric and ferrous ions  

NASA Astrophysics Data System (ADS)

Bombyx mori silk fiber has useful mechanical properties largely due to a high content of ordered ?-sheet crystallites separated by non-crystalline spacers. Metallic ions present in the silk dope in nature could affect the ?-sheet content. In this work, we used solid-state 13C NMR, EPR and Raman spectroscopy to investigate how the ferric/ferrous ions affect the folding process of the silk fibroin. NMR and Raman results indicate that ferric and ferrous ions have different effects on the secondary structure of silk fibroin. Ferric ions can induce a conformation change from helix to ?-sheet form in silk fibroin when their concentration exceeds a critical value, while ferrous ions cannot. EPR results indicate that the ferric ions bound with silk fibroin have a high-spin state ( S = 5/2) with g-value of g1 = 1.950, g2 = 1.990 and g3 = 1.995, zero-field splitting interaction D of 1.2-2 cm -1, and symmetric character of E/ D = 1/3, resulting in an effective g-value of g' = 4.25. The hydrophilic spacer GTGSSGFGPYVAN(H)GGYSGYEYAWSSESDFGT in the heavy chain of silk fibroin is likely to be involved in the binding of ferric ions, and His, Asn and Tyr residues are considered as the potential binding sites.

Ji, Dan; Deng, Yi-Bin; Zhou, Ping

2009-12-01

355

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

356

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

357

Colour and stability assessment of blue ferric anthocyanin chelates in liquid pectin-stabilised model systems.  

PubMed

The formation of blue coloured ferric anthocyanin chelates and their colour stability during storage and thermal treatment were monitored in a pH range relevant to food (3.6-5.0). Liquid model systems were composed of different types of Citrus pectins, juices (J) and the respective phenolic extracts (E) from elderberry (EB), black currant (BC), red cabbage (RC) and purple carrot (PC) in the presence of ferric ions. For EB, BC and PC, pure blue colours devoid of a violet tint were exclusively observed for the phenolic extracts and at pH values ? 4.5 in model systems containing high methoxylated and amidated pectins, respectively. Colour and its stability strongly depended on the amount of ferric ions and the plant source; however, colour decay could generally be described as a pseudo-first-order kinetics. Despite optimal colour hues for RC-E and RC-J, storage and heat stabilities were poor. Highest colour intensities and best stabilities were observed for model systems containing PC-E at a molar anthocyanin:ferric ion ratio of 1:2. Ascorbic and lactic acids interfered with ferric ions, thus significantly affecting blue colour evolution and stability. Colour loss strongly depended on heat exposure with activation energies ranging between 60.5 and 78.4 kJ/mol. The comprehensive evaluation of the interrelationship of pigment source, pH conditions and pectin type on chelate formation and stability demonstrated that ferric anthocyanin chelates are promising natural blue food colourants. PMID:23411339

Buchweitz, M; Brauch, J; Carle, R; Kammerer, D R

2013-06-01

358

Investigations of Ferric Heme Cyanide Photodissociation in Myoglobin and Horseradish Peroxidase  

PubMed Central

The photodissociation of cyanide from ferric myoglobin (MbCN) and horseradish peroxidase (HRPCN) has been definitively observed. This has implications for the interpretation of ultrafast IR (Helbing et al. Biophys. J. 2004, 87, 1881–1891) and optical (Gruia et al. Biophys. J. 2008, 94, 2252–2268) studies that had previously suggested the Fe-CN bond was photostable in MbCN. The photolysis of ferric MbCN takes place with a quantum yield of ~75% and the resonance Raman spectrum of the photoproduct observed in steady-state experiments as a function of laser power and sample spinning rate is identical to that of ferric Mb (metMb). The data are quantitatively analyzed using a simple model where cyanide is photodissociated and, although geminate rebinding with a rate kBA ? (3.6 ps)?1 is the dominant process, some CN? exits from the distal heme pocket and is replaced by water. Using independently determined values for the CN? association rate, we find that the CN? escape rate from the ferric myoglobin pocket to the solution at 293 K is kout ? 1–2 × 107 s?1. This value is very similar to, but slightly larger than, the histidine gated escape rate of CO from Mb (1.1×107 s?1) under the same conditions. The analysis leads to an escape probability kout/(kout+kBA) ~ 10?4, which is unobservable in most time domain kinetic measurements. However, the photolysis is surprisingly easy to detect in Mb using cw resonance Raman measurements. This is due to the anomalously slow CN? bimolecular association rate (170 M?1s?1), which arises from the need for water to exchange at the ferric heme binding site of Mb. In contrast, ferric HRP does not have a heme bound water molecule and its CN? bimolecular association rate is larger by ~103 making the CN? photolysis more difficult to observe.

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

2013-01-01

359

Palladium/zirconium oxide nanocomposite as a highly recyclable catalyst for C-C coupling reactions in water.  

PubMed

Palladium nanoparticles have been electrochemically supported on zirconium oxide nanostructured powders and all the nanomaterials have been characterized by several analytical techniques. The Pd/ZrO(2) nanocatalyst is demonstrated to be a very efficient catalyst in Heck, Ullmann, and Suzuki reactions of aryl halides in water. The catalyst efficiency is attributed to the stabilization of Pd nanophases provided by tetra(alkyl)- ammonium hydroxide, which behaves both as base and PTC (phase transfer catalyst) agent. PMID:20657374

Monopoli, Antonio; Nacci, Angelo; Calò, Vincenzo; Ciminale, Francesco; Cotugno, Pietro; Mangone, Annarosa; Giannossa, Lorena Carla; Azzone, Pietro; Cioffi, Nicola

2010-07-01

360

Intraparticle diffusion and adsorption of arsenate onto granular ferric hydroxide (GFH).  

PubMed

Porous iron oxides are being evaluated and selected for arsenic removal in potable water systems. Granular ferric hydroxide, a typical porous iron adsorbent, is commercially available and frequently considered in evaluation of arsenic removal methods. GFH is a highly porous (micropore volume approximately 0.0394+/-0.0056 cm(3)g(-1), mesopore volume approximately 0.0995+/-0.0096 cm(3)g(-1)) adsorbent with a BET surface area of 235+/-8 m(2)g(-1). The purpose of this paper is to quantify arsenate adsorption kinetics on GFH and to determine if intraparticle diffusion is a rate-limiting step for arsenic removal in packed-bed treatment systems. Data from bottle-point isotherm and differential column batch reactor (DCBR) experiments were used to estimate Freundlich isotherm parameters (K and 1/n) as well as kinetic parameters describing mass transfer resistances due to film diffusion (k(f)) and intraparticle surface diffusion (D(s)). The pseudo-equilibrium (18 days of contact time) arsenate adsorption density at pH 7 was 8 microg As/mg dry GFH at a liquid phase arsenate concentration of 10 microg As/L. The homogeneous surface diffusion model (HSDM) was used to describe the DCBR data. A non-linear relationship (D(S)=3.0(-9) x R(p)(1.4)) was observed between D(s) and GFH particle radius (R(P)) with D(s) values ranging from 2.98 x 10(-12) cm(2)s(-1) for the smallest GFH mesh size (100 x 140) to 64 x 10(-11) cm(2)s(-1) for the largest GFH mesh size (10 x 30). The rate-limiting process of intraparticle surface diffusion for arsenate adsorption by porous iron oxides appears analogous to organic compound adsorption by activated carbon despite differences in adsorption mechanisms (inner-sphere complexes for As versus hydrophobic interactions for organic contaminants). The findings are discussed in the context of intraparticle surface diffusion affecting packed-bed treatment system design and application of rapid small-scale column tests (RSSCTs) to simulate the performance of pilot- or full-scale systems at the bench-scale. PMID:15380990

Badruzzaman, Mohammad; Westerhoff, Paul; Knappe, Detlef R U

2004-11-01

361

Kinetics of the Decomposition of Hydrogen Peroxide Catalyzed by Ferric Ethylenediaminetetraacetate Complex  

PubMed Central

Added substrates, acetone and t-butyl alcohol, strongly retard the decomposition of H2O2 brought about by ferric ethylenediaminetetraacetate (EDTA) at pH 8-9.5. Their relative effectiveness and the kinetic form of the retardation are consistent with their interruption of a hydroxyl radical chain that is propagated by HO· attack both upon H2O2 and on complexed and uncomplexed EDTA. Similar retardation is observed with decompositions catalyzed by ferric nitrilotriacetate and hemin, and it is proposed that such redox chains may be quite a general path for transition metal ion catalysis of H2O2 decomposition.

Walling, Cheves; Partch, Richard E.; Weil, Tomas

1975-01-01

362

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

363

Removal of arsenic from drinking water by ferric hydroxide microcapsule-loaded alginate beads in packed adsorption column  

Microsoft Academic Search

In this paper we have presented a unique low cost arsenic removal technique using ferric hydroxide microcapsule-loaded alginate beads (FHMCA) as an adsorbent in a continuous packed column. The microencapsulated particles of ferric hydroxide were produced in a spray dryer and subsequently coated with calcium alginate to form spherical beads of about 2 mm diameter. Batch experiments were conducted with

Priyabrata Sarkar; Priyabrata Pal; Dipankar Bhattacharyay; Suchanda Banerjee

2010-01-01

364

Process for the synthesis of nanophase dispersion-strengthened aluminum alloy  

DOEpatents

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

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

1998-12-15

365

Metal tungstates at the ultimate two-dimensional limit: fabrication of a CuWO? nanophase.  

PubMed

Metal tungstates (with general formula MWO4) are functional materials with a high potential for a diverse set of applications ranging from low-dimensional magnetism to chemical sensing and photoelectrocatalytic water oxidation. For high level applications, nanoscale control of film growth is necessary, as well as a deeper understanding and characterization of materials properties at reduced dimensionality. We succeeded in fabricating and characterizing a two-dimensional (2-D) copper tungstate (CuWO4). For the first time, the atomic structure of an ultrathin ternary oxide is fully unveiled. It corresponds to a CuWO4 monolayer arranged in three sublayers with stacking O-W-O/Cu from the interface. The resulting bidimensional structure forms a robust framework with localized regions of anisotropic flexibility. Electronically it displays a reduced band gap and increased density of states close to the Fermi level with respect to the bulk compound. These unique features open a way for new applications in the field of photo- and electrocatalysis, while the proposed synthesis method represents a radically new and general approach toward the fabrication of 2-D ternary oxides. PMID:24617647

Denk, Martin; Kuhness, David; Wagner, Margareta; Surnev, Svetlozar; Negreiros, Fabio R; Sementa, Luca; Barcaro, Giovanni; Vobornik, Ivana; Fortunelli, Alessandro; Netzer, Falko P

2014-04-22

366

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

367

Superparamagnetic resonance of ferric ions in devitrified borate glass  

Microsoft Academic Search

Drastic changes are observed in magnetic resonance spectra of borate glasses doped with low concentrations of iron oxide, after heat treatment above the glass transition temperature. A sharp gef = 4.3 line, characteristic of diluted Fe3+ ions in the vitreous matrix, progressively disappears in the course of treatment. A new two-line pattern grows in the vicinity of gef ? 2.0,

René Berger; Jean-Claude Bissey; Janis Kliava; Benoît Soulard

1997-01-01

368

Formation of films in hydrolysing ferric chloride solutions  

Microsoft Academic Search

FRYER et al.1,2 have postulated that two-dimensional polymeric structures may be formed in solution when metal-ion salts undergo self-hydrolysis before the precipitation of some hydrated crystalline oxides such as alpha FeO.OH, beta; FeO.OH, and V2O5.H2O. They reported that these structures or films can only be seen by spraying a hydrolysing solution onto a mesh of asbestos fibres when the film

T. M. Armitage; A. M. Posner

1978-01-01

369

The Intermetalloid Cluster [(Cp*AlCu)6 H4 ], Embedding a Cu6 Core Inside an Octahedral Al6 Shell: Molecular Models of Hume-Rothery Nanophases.  

PubMed

Defined molecular models for the surface chemistry of Hume-Rothery nanophases related to catalysis are very rare. The Al-Cu intermetalloid cluster [(Cp*AlCu)6 H4 ] was selectively obtained from the clean reaction of [(Cp*Al)4 ] and [(Ph3 PCuH)6 ]. The stronger affinity of Cp*Al towards Cu sweeps the phosphine ligands from the copper hydride precursor and furnishes an octahedral Al6 cage to encapsulate the Cu6 core. The resulting hydrido cluster M12 H4 reacts with benzonitrile to give the stoichiometric hydrometalation product [(Cp*AlCu)6 H3 (N=CHPh)]. PMID:24962074

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

2014-07-21

370

Nano-phase titanium dioxide thin film deposited by repetitive plasma focus: Ion irradiation and annealing based phase transformation and agglomeration  

Microsoft Academic Search

We report the successful deposition of nano-phase crystalline titanium\\u000a dioxide (TiO(2)) thin films using a repetitive plasma focus device on\\u000a silicon (Si) substrates at room temperature. The plasma focus device,\\u000a fitted with solid titanium anode was operated with argon-oxygen\\u000a admixture as the filling gas. X-ray diffraction (XRD) patterns of\\u000a as-deposited films confirm the deposition of crystalline TiO(2) thin\\u000a films having

R. S. Rawat; V. Aggarwal; M. Hassan; P. Lee; S. V. Springham; T. L. Tan; S. Lee

2008-01-01

371

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

372

Efficacy and Safety of Ferric Chloride in Controlling Hepatic Bleeding; An Animal Model Study  

PubMed Central

Background: Controlling parenchymal hemorrhage especially in liver parenchyma, despite all the progress in surgical science, is still one of the challenges surgeons face saving patients’ lives and there is a research challenge among researchers in this field to introduce a more effective method. Objectives: This study attempts to determine the haemostatic effect of ferric chloride and compare it with that of the standard method (suturing technique) in controlling bleeding from liver parenchymal tissue. Materials and Methods: In this animal model study 60 male Wistar rats were used. An incision, two centimeters (cm) long and half a cm deep, was made on each rat’s liver and the hemostasis time was measured once using ferric chloride with different concentrations (5%, 10%, 15%, 25% and 50%) and then using the control method (i.e. controlling bleeding by suturing). The liver tissue was examined for pathological changes. Results: The hemostasis time of ferric chloride concentration groups was significantly less than that of the control group (P value < 0.001). The pathologic examination showed the highest frequency of low grade inflammation based on the defined pathological grading. Conclusions: Ferric chloride is an effective haemostatic agent in controlling liver parenchymal tissue hemorrhage in an animal model.

Nouri, Saeed; Sharif, Mohammad Reza

2014-01-01

373

Arsenic removal by iron-doped activated carbons prepared by ferric chloride forced hydrolysis  

Microsoft Academic Search

Ferric chloride forced hydrolysis is shown to be a good method for increasing the iron content of activated carbons (ACs). Iron content increased linearly with hydrolysis time, and ACs with iron content as high as 9.4wt.% at 24h hydrolysis time could be prepared. The increase in iron content did not produce any modification in the textural parameters determined by nitrogen

V. Fierro; G. Muñiz; G. Gonzalez-Sánchez; M. L. Ballinas; A. Celzard

2009-01-01

374

Intravenous Iron Replacement with Sodium Ferric Gluconate Complex in Sucrose for Iron Deficiency Anemia in Adults  

Microsoft Academic Search

Background: When oral iron replacement therapy is ineffective, IV or IM iron dextran products have been used successfully in many patients. However, adverse events, including urticaria, anaphylaxis, and death, sometimes are associated with the use of these products.Objective: The aim of this study was to assess the efficacy and tolerability of sodium ferric gluconate complex (SFGC) in sucrose in the

Robert C Kane

2003-01-01

375

Safety and efficacy of sodium ferric gluconate complex in patients with chronic kidney disease  

Microsoft Academic Search

Background: We hypothesized that intravenous iron will improve hemoglobin (Hgb) concentrations in anemic patients with chronic kidney disease (CKD), and the response would be greater if the underlying erythropoietin deficiency also was treated. Methods: Charts of 58 CKD veterans (glomerular filtration rate < 80 mL\\/min) administered at least 125 mg of sodium ferric gluconate complex in sucrose (SFGC) during a

Atinder Panesar; Rajiv Agarwal

2002-01-01

376

Ferric gluconate treatment provides cost savings in patients with high ferritin and low transferrin saturation  

Microsoft Academic Search

A subgroup of hemodialysis patients experience high serum ferritin and low tansferrin saturation for reasons not clearly understood. Here we determined the economic impact of administering sodium ferric gluconate complex to patients with serum ferritin levels higher than 500 ng\\/ml and a transferrin saturation less than 25% based on the Dialysis Patients Response to IV Iron with Elevated Ferritin (DRIVE)

Laura T Pizzi; Thomas J Bunz; Daniel W Coyne; David S Goldfarb; Ajay K Singh

2008-01-01

377

Drug Insight: safety of intravenous iron supplementation with sodium ferric gluconate complex  

Microsoft Academic Search

Intravenous iron is necessary for optimal management of anemia in patients receiving hemodialysis and is utilized in the majority of these patients in the US. The availability of nondextran formulations of intravenous iron has significantly improved the safety of its use. The nondextran iron formulation sodium ferric gluconate complex (SFGC) has been extensively studied in the hemodialysis population, with two

Steven Fishbane; Daniel W Coyne; Rajiv Agarwal; David G Warnock; Beckie Michael

2006-01-01

378

Determination of Iron in Solutions with the Ferric–Xylenol Orange Complex  

Microsoft Academic Search

Formation of a colored complex between ferric iron and xylenol orange has been used in a variety of applications, but there is disagreement about the number of complexes that exist, their stoichiometry, pH dependence, solvent effects, and other parameters. In this study we investigated the use of the complex to measure micromolar concentrations of iron in aqueous and alcohol solutions.

Craig Gay; James Collins; Janusz M. Gebicki

1999-01-01

379

The rate of decomposition of the ferric-thiosulfate complex in acidic aqueous solutions  

Microsoft Academic Search

The rate of decomposition of the ferric thiosulfate complex varies as the square of the concentration of the complex. The rate of decomposition of the complex was determined by following the change in absorbance due to the complex as a function of time. Regression of log rate vs. log m[sub FeS[sub 2]O[sub 3][sup +

M. A. Williamson; J. D. Rimstidt

1993-01-01

380

The rate of decomposition of the ferric-thiosulfate complex in acidic aqueous solutions  

SciTech Connect

The rate of decomposition of the ferric thiosulfate complex varies as the square of the concentration of the complex. The rate of decomposition of the complex was determined by following the change in absorbance due to the complex as a function of time. Regression of log rate vs. log m[sub FeS[sub 2]O[sub 3][sup +

Williamson, M.A.; Rimstidt, J.D. (Virginia Polytechnic Inst. State Univ., Blacksburg (United States))

1993-08-01

381

Ferric ion as a scavenging agent in a solvent extraction process  

Microsoft Academic Search

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

Lester E. Bruns; Earl C. Martin

1976-01-01

382

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 ...

383

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

EPA Science Inventory

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

384

Martian weathering/alteration scenarios from spectral studies of ferric and ferrous minerals  

NASA Technical Reports Server (NTRS)

We review the major aspects of our current knowledge of martian ferric and ferrous mineralogy based on the available ground-based telescopic and spacecraft data. What we know and what we don't know are used to constrain various weathering/alteration models and to identify key future measurements and techniques that can distinguish between these models.

Bell, James F., III; Adams, John B.; Morris, Richard V.

1992-01-01

385

Use of Ferric Chloride in Carbohydrate Reactions. Iv. Acetolysis of Benzyl Ethers of Sugars  

Microsoft Academic Search

Acetolysis of benzyl ethers of sugars has been carried out with anhydrous ferric chloride in acetic anhydride. By employing this reagent, benzyl ether groups variously placed in sugars or in their glycosides could be removed with ease and replaced by acetyl groups. By controlled acetolysis, preferential removal of certain benzyl groups was possible. The results show that in D-glucose the

K. P. R. Kartha; F. Dasgupta; P. P. Singh; H. C. Srivastava

1986-01-01

386

The extraction of ferric chloride with methyl isobutyl ketone and amyl acetate  

Microsoft Academic Search

The extraction of iron as ferric chloride in 7 M hydrochloric acid by a mixture of (1+1) or (2+1) methyl isobutyl ketone and amyl acetate is quantitative for macro as well as for micro amounts of iron. The distribution ratio is very high (~ 4000). With these mixtures no emulsification difficulties are encountered as they are with methyl isobutyl ketone

A. Claassen; L. Bastings

1958-01-01

387

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

PubMed Central

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

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

2011-01-01

388

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

2012-10-01

389

Oxidation and coagulation of humic substances by potassium ferrate.  

PubMed

Ferrate (FeO?²?) is believed to have a dual role in water treatment, both as oxidant and coagulant. Few studies have considered the coagulation effect in detail, mainly because of the difficulty of separating the oxidation and coagulation effects. This paper summarises some preliminary results from laboratory-based experiments that are investigating the coagulation reaction dynamically via a PDA instrument, between ferrate and humic acid (HA) at different doses and pH values, and comparing the observations with the use of ferric chloride. The PDA output gives a comparative measure of the rate of floc growth and the magnitude of floc formation. The results of the tests show some significant differences in the pattern of behaviour between ferrate and ferric chloride. At pH 5 the chemical dose range (as Fe) corresponding to HA coagulation was much broader for ferrate than ferric chloride, and the optimal Fe dose was greater. Ferrate oxidation appears to increase the hydrophilic and electronegative nature of the HA leading to an extended region of charge neutralisation. A consequence of the ferrate oxidation is that the extent of HA removal was slightly lower ( approximately 5%) than with ferric chloride. At pH 7, in the sweep flocculation domain, ferrate achieved much greater floc formation than ferric chloride, but a substantially lower degree of HA removal. PMID:20729598

Graham, N J D; Khoi, T T; Jiang, J-Q

2010-01-01

390

Purpose-Built Anisotropic Metal Oxide Nanomaterials.  

National Technical Information Service (NTIS)

Large arrays of perpendicularly oriented anisotropic nanoparticles of ferric oxyhydroxide (Akaganeite, beta-FeOOH) and oxide (Hematite, alpha-Fe2O3) of typically 3-5 nm in diameter, self assembled as bundles of about 50 nm in diameter and of up to 1 micro...

L. Vayssieres J. Guo J. Nordgren

2001-01-01

391

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

392

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

PubMed Central

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

Thomas, Anila; Peterson, Leif E

2014-01-01

393

Ferric alpha-hydroxyheme bound to heme oxygenase can be converted to verdoheme by dioxygen in the absence of added reducing equivalents.  

PubMed

Whether or not reducing equivalents are indispensable for the conversion of ferric alpha-hydroxyheme bound to heme oxygenase-1 to verdoheme remains controversial (Matera, K. M., Takahashi, S., Fujii, H., Zhou, H., Ishikawa, K., Yoshimura, T., Rousseau, D. L., Yoshida, T., and Ikeda-Saito, M. (1996) J. Biol. Chem. 271, 6618-6624; Liu, Y., Moënne-Loccoz, P., Loehr, T. M., and Ortiz de Montellano, P. R. (1997) J. Biol. Chem. 272, 6906-6917). To resolve this controversy, we have prepared a ferric alpha-hydroxyheme-heme oxygenase-1 complex and titrated the complex with O2 under strictly anaerobic conditions. The formation of verdoheme was monitored by optical and electron spin resonance spectroscopies. Electron spin resonance spectra of the complex showed that alpha-hydroxyheme exists as a mixture of resonance structures composed of the iron(III) porphyrin and the iron(II) porphyrin pi neutral radical. Upon addition of CO the latter species becomes dominant. The results obtained from these titration experiments indicate that alpha-hydroxyheme can be converted to verdoheme by an approximately equimolar amount of O2 without any requirement for exogenous electrons. The verdoheme formed from alpha-hydroxyheme was shown to be in the ferrous oxidation state by the addition of CO or potassium ferricyanide to the resultant verdoheme-heme oxygenase-1 complex. PMID:10373419

Sakamoto, H; Omata, Y; Palmer, G; Noguchi, M

1999-06-25

394

Reaction of ferric cytochrome P450cam with peracids: kinetic characterization of intermediates on the reaction pathway.  

PubMed

Reactions of substrate-free ferric cytochrome P450cam with peracids to generate Fe=O intermediates have previously been investigated with contradictory results. Using stopped-flow spectrophotometry, the reaction with m-chloroperoxybenzoic acid demonstrated an Fe(IV)=O + porphyrin pi-cation radical (Cpd I) (Egawa, T., Shimada, H., and Ishimura, Y. (1994) Biochem. Biophys. Res. Commun. 201, 1464-1469). By contrast, with peracetic acid, Fe(IV)=O plus a tyrosyl radical were observed by freeze-quench Mossbauer and EPR spectroscopy (Schunemann, V., Jung, C., Trautwein, A. X., Mandon, D., and Weiss, R. (2000) FEBS Lett. 479, 149-154). Our detailed kinetic studies have resolved these contradictory results. At pH >7, a significant fraction of Cpd I is formed transiently, whereas at low pH only a species with a Soret band at 406 nm, presumably Fe(IV)=O + tyrosyl radical, is observed. Evidence for formation of an acylperoxo complex en route to Cpd I was obtained. Because of rapid heme destruction, steps subsequent to formation of the highly oxidized forms could not be fully characterized. Heme destruction was avoided by including peroxidase substrates (e.g. guaiacol), which were oxidized to characteristic peroxidase products as the Fe(III)-P450 was regenerated. Addition of ascorbate to either of the high valent species also reforms the Fe(III) state with only a small loss of heme absorbance. These results indicate that typical peroxidase chemistry occurs with P450cam and offer an explanation for the contrasting results reported earlier. The delineation of improved conditions (pH, temperature, choice of peracid) for generating highly oxidized species with P450cam should be valuable for their further characterization. PMID:15781454

Spolitak, Tatyana; Dawson, John H; Ballou, David P

2005-05-27

395

Comparison of different bioreactor systems for indirect H 2S removal using iron-oxidizing bacteria  

Microsoft Academic Search

Microbial oxidation of ferrous iron may be available alternative method of producing ferric sulphate, which is a reagent used for removal of H2S from biogas. For practical use of this process, this study evaluated some of the most efficient bioreactor systems for continuous ferrous iron oxidation by iron-oxidizing bacteria. Performances of various bioreactor systems were compared based on the ferrous

Donghee Park; Dae Sung Lee; Jae Youl Joung; Jong Moon Park

2005-01-01

396

A Comparison of Strontium Sorption to Hydrous Aluminum, Iron, and Manganese Oxides  

Microsoft Academic Search

Strontium sorption to hydrous aluminum (HAO) and manganese (HMO) oxides was studied using macroscopic studies on short- and long-term bases. These studies were compared with previous results for strontium sorption to hydrous ferric oxide (HFO). Sorption to these microporous oxides can be described as a two-step process: a rapid and reversible adsorption reaction to the external surface including the macropores

Paras Trivedi; Lisa Axe

1999-01-01

397

Chemical reactivity of microbe and mineral surfaces in hydrous ferric oxide depositing hydrothermal springs  

Microsoft Academic Search

The hot springs in Yellowstone National Park, USA, provide concentrated microbial biomass and associated mineral crusts from which surface functional group (FG) concentrations and pK a distributions can be determined. To evaluate the importance of substratum surface reactivity for solute adsorption in a natural setting, samples of iron-rich sediment were collected from three different springs; two of the springs were

S. V. LALONDE; L. AMSKOLD; T. R. MCDERMOTT; W. P. INSKEEP; K. O. KONHAUSER

2007-01-01

398

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

399

Photoacoustic measurements of water–gas shift reaction on ferric oxide catalyst  

Microsoft Academic Search

A photoacoustic spectroscopic (PAS) technique was applied to the kinetic study of the water–gas shift reaction in the presence of ?-Fe2O3 catalyst. The catalytic reaction was performed in the temperature range from 523 to 673K at various partial pressures of carbon monoxide and water–vapor in a closed-circulation reactor system using a differential photoacoustic cell. The variation of CO2 photoacoustic signal

Su-Jin Kim; In-Sik Byun; Ho-Youn Han; Hong-Lyoul Ju; Sung Han Lee; Joong-Gill Choi

2002-01-01

400

Arsenite and arsenate sorption by hydrous ferric oxide\\/polymeric material  

Microsoft Academic Search

The occurrence of arsenic in natural ground waters is due to geological composition of soil. There are several methods for removal of arsenic from drinking water, such as coagulation followed by filtration, membrane processes, ion exchange and adsorption. Adsorption methods proved to be effective, economic, easy to perform and construct. The objective of this study was to investigate the removal

Mirna Habuda-Stani?; Brankica Kalajdži?; Mirko Kuleš; Natalija Veli?

2008-01-01

401

Studying high-spin ferric heme proteins by pulsed EPR spectroscopy: Analysis of the ferric form of the E7Q mutant of human neuroglobin  

Microsoft Academic Search

In this work, the high-spin ferric form of the E7Q mutant of human neuroglobin (E7Q-NGB) is studied by X-band continuous-wave\\u000a electron paramagnetic resonance (CW EPR) and hyperfine sublevel correlation (HYSCORE) spectroscopy. It is shown that the use\\u000a of matched pulses in the HYSCORE experiment is essential to observe the nitrogen spectral contributions. The validity of approximating\\u000a the high-spin Fe(III) system

F. Trandafir; P. Heerdt; M. Fittipaldi; E. Vinck; S. Dewilde; L. Moens; S. Van Doorslaer

2007-01-01

402

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

403

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

404

Corynebactin and a serine trilactone based analogue: chirality and molecular modeling of ferric complexes.  

PubMed

Because the hydrolysis of ferric ion makes it very insoluble in aerobic, near neutral pH environments, most species of bacteria produce siderophores to acquire iron, an essential nutrient. The chirality of the ferric siderophore complex plays an important role in cell recognition, uptake, and utilization. Corynebactin, isolated from Gram-positive bacteria, is structurally similar to enterobactin, a well-known siderophore first isolated from Gram-negative bacteria, but contains L-threonine instead of L-serine in the trilactone backbone. Corynebactin also contains a glycine spacer unit in each of the chelating arms. A hybrid analogue (serine-corynebactin) has been prepared which has the trilactone ring of enterobactin and the glycine spacer of corynebactin. The chirality and relative conformational stability of the three ferric complexes of enterobactin, corynebactin, and the hybrid have been investigated by molecular modeling (including MM3 and pBP86/DN density functional theory calculations) and circular dichroism spectra. While enterobactin forms a Delta-ferric complex, corynebactin is Lambda. The hybrid serine-corynebactin forms a nearly racemic mixture, with the Lambda-conformer in slight excess. Each ferric complex has four possible isomers depending on the metal chirality and the conformation of the trilactone ring. For corynebactin, the energy difference between the two possible Lambda conformations is 2.3 kcal/mol. In contrast, only 1.5 kcal/mol separates the inverted Lambda- and normal Delta-configuration for serine-corynebactin. The small energy difference of the two lowest energy configurations is the likely cause for the racemic mixture found in the CD spectra. Both the addition of a glycine spacer and methylation of the trilactone ring (serine to threonine) favor the Lambda-conformation. These structural changes suffice to change the chirality from all Delta (enterobactin) to all Lambda (corynebactin). The single change (glycine spacer) of the hybrid ferric serine-corynebactin gives a mixture of Delta and Lambda, with the Lambda in slight excess. PMID:12377042

Bluhm, Martin E; Hay, Benjamin P; Kim, Sanggoo S; Dertz, Emily A; Raymond, Kenneth N

2002-10-21

405

The effect of surfactants on growth and form of monodispersed iron oxide particles  

Microsoft Academic Search

The effects of added surfactants on the size and shape of the monodispersed iron oxide particles prepared by forced hydrolysis\\u000a from aqueous ferric chloride solutions were investigated by transmission electron microscopes. When the concentration of ferric\\u000a chloride solutions increased, either the particle growth displayed clear delays or only a reaction intermediate of ?-FeOOH\\u000a was made. The cation and the amphoteric

Su-Jin Koo; Jae-kee Cheon

2006-01-01

406

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

407

Measurement of lipid hydroperoxides by the ferric-xylenol orange method (1) characteristics of the ferric-xylenol orange/membrane phosphatidylcholine complex.  

PubMed

The ferric-xylenol orange (FOX) method for measurement of hydroperoxides is based on a technique that employs reduction of peroxides in an acidic condition by Fe2+ and formation of the colored ferric-xylenol orange (XO/Fe3+) product with a peak at 560 nm. The 560 nm absorbance peak of XO/Fe3+ shifts to a 610 nm peak with high absorption intensity in the presence of phosphatidylcholine. This is useful for quantification of peroxides such as phospholipid hydroperoxides. Based on this finding, we recently reported a modified FOX method. We now show by measurements of absorbance, broadening of the electron paramagnetic resonance spectrum, changes in the vesicle size and their zeta potentials, the effects of detergents, and manipulation of the membrane lipid composition that the XO/Fe3+-phosphatidylcholine complex forms only in the presence of intact phosphatidylcholine membranes. The phosphate group on the phospholipid plays a role in this interaction which may involve an electron transfer from the phosphate to the Fe3+. A positively charged quaternary amine on the phosphatidylcholine is also necessary to give a peak absorbance at 610 nm. Our observations are consistent with binding of one XO/Fe3+ complex to about 3 molecules of the egg yolk phosphatidylcholine carrying a zero net charge. PMID:19352058

Fukuzawa, Kenji; Shibata, Akira; Okamura, Chika; Fujiwara, Yuhki; Akai, Kaori; Tsuchiya, Koichiro; Tokumura, Akira; Gebicki, Janusz M

2009-02-01

408

The perplexing continuum slope of Mars: Effects of thin ferric coatings and viewing geometry  

NASA Technical Reports Server (NTRS)

The experiment discussed here was designed to constrain interpretations of variations in continuum slope variations which define several spectral annuli on the flanks of Olympus Mons, observed in the Imaging Spectrometer (IMS) data. The IMS Olympus Mons data reveal that the rings, seen as alternating brighter and darker reflectance in Viking data, correspond to annuli of alternating shallower and steeper continuum slope. At least three factors contributing to continuum slope are identified: ferric coating thickness, viewing geometry, and surface texture. Because the Olympus Mons spectral annuli were observed at nearly constant backscatter geometries in the ISM data, with only slight viewing variations due to the volcanoe's flank slopes, the difference of continuum slope between annuli probably cannot be explained by viewing geometry alone. This suggests that the variation of some fundamental surface characteristics, such as ferric dust/rind thickness or surface texture, is the cause of the Olympus Mons special annuli observed in the ISM imaging spectrometer data.

Fischer, Erich M.; Pieters, Carle M.; Pratt, Stephen F.

1991-01-01

409

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

410

Method of inhibiting crosslinking of aqueous xanthan gums in the presence of ferric acid ions  

SciTech Connect

The cross linking of aqueous xanthan gums in the presence of ferric ions is inhibited or prevented by adding a soluble alkanoic and/or alkenoic acid having at least 4 carbon atoms and bearing at least 2 hydroxyl groups per molecule, and/or a soluble salt of ..gamma..-lactone. This combination of ingredients forms gelled acid compositions which are useful in acidizing treatments of wells. The gelled acid compositions are viscous fluids which have increased stability against shear and thermal degradation and other properties which result in retarded reaction rates and reduced fluid leak-off during acidizing treatments of subterranean formations surrounding well bores. The aqueous gelled acids have the further advantage of inhibiting or preventing the formation of insoluble compounds, such as ferric hydroxide, during such acidizing treatments. 13 claims.

Crowe, C.W.

1982-03-02

411

Simultaneous X-ray and neutron diffraction Rietveld refinements of nanophase iron substituted hydroxyapatite  

NASA Astrophysics Data System (ADS)

The effect of Fe substitution on the crystal structure of hydroxyapatite (HAp) is studied by applying simultaneous Rietveld refinements of powder x-ray and neutron diffraction patterns. Fe is one of the trace elements replacing Ca in HAp, which is the major mineral phase in bones and teeth. The morphology and magnetic properties of the Fe-HAp system are also studied by transmission electron microscopy and magnetization measurements. Samples of Ca(5-x)Fex(PO4)3OH with 0 ? x ? 0.3 were prepared. Single phase HAp was identified in x-ray diffraction patterns (XRD) of samples with x < 0.1 inferring that the solubility limits are less than 0.1. Hematite (alpha-Fe2O3) is identified as a secondary phase for higher Fe content. The refined parameters show that Fe is incorporated in the HAp structure by replacing Ca in the two crystallographic sites with a preference at the Ca2 site. This preference explains the small effect of the Fe substitution on the lattice constants of HAp. The overall decrease of the lattice constants is explained by the ionic size difference of Ca and Fe. The increasing trend of the a-lattice constant with x in the Fe substituted samples is attributed to a lattice relaxation caused by the substitution of the 4- and 6-fold Fe at the 7- and 9-fold Ca1 and Ca2 sites. This Ca local geometry reduction is indicated by a slight increase of the Ca1-O3 and Ca2-O1 bond lengths. Above the solubility limit x = 0.05, the Fe is partitioned in and out of the HAp structure with increasing nominal Fe content x. The excess Fe is oxidized to hematite. The TEM analysis and magnetic measurements support the results of the simultaneous Rietveld refinements. The TEM images show no significant effect on the morphology and size of the HAp particles upon Fe incorporation. The particles are either spheres or short rods of dimensions 20--60 nm. Hematite particles are imaged in the samples with x exceeding the solubility limit. These particles are spheres, about 15 nm in diameter and are more resistant to electron beam damage. Magnetic measurements reveal a transition of the diamagnetic pure HAp to paramagnetic Fe substituted HAp.

Kyriacou, Andreas

412

An investigation into the leaching kinetics of cobaltite ore with ferric sulfate solutions  

Microsoft Academic Search

A method for the extraction of cobalt from cobalt-arsenic-sulfide (cobaltite) ores or concentrates has been identified. The\\u000a method utilizes an atmospheric oxygen-acidic ferric sulfate leach, at temperatures up to 373 K (100?C), to place the cobalt\\u000a in solution. Extraction of 80 pct of the cobalt was obtained within 24 h and the tests indicate that greater and more rapid\\u000a extractions

P. R. Taylor; J. P. Vanderloop

1980-01-01

413

Phosphorous removal in batch systems using ferric chloride in the presence of activated sludges.  

PubMed

The objectives of this work were: (a) to analyze the effect of alkalinity, pH and initial Fe:P molar ratio (Fe(0):P(0)) on the precipitation of orthophosphate using ferric chloride in the presence of activated sludge in order to represent conditions of simultaneous precipitation, and in exhausted wastewater to simulate conditions of post-precipitation, (b) to compare the experimental results with predictions obtained from a chemical equilibrium model, and (c) to propose a mechanistic model to determine the dose of coagulant required to achieve a given orthophosphate removal degree at constant pH. Results showed that the presence of biomass did not affect the orthophosphate precipitation; however, addition of ferric chloride caused a drop of pH to values not compatible with the normal activity of activated sludges. For this reason, the wastewater was supplemented with NaHCO(3); when 1gL(-1) NaHCO(3) was added, orthophosphate removals higher than 97% and pH above 6.2 were obtained using Fe(0):P(0)=1.9. Precipitation assays at constant pH showed that Fe(III) hydrolysis and FePO(4) precipitation reaction compete with each other. Calculations using a chemical equilibrium model (CHEAQS) predicted that ferric phosphate precipitation should not take place if pH is higher than about 7.8. However, experimental results showed that ferric phosphate precipitation occurred even at pH 9. For this reason, a mechanistic model was proposed to predict orthophosphate concentrations as a function of Fe(0):P(0) at constant pH. The model can be applied to calculate the minimum Fe(III) concentration required to achieve a given discharge limit for orthophosphate as a function of its initial concentration and pH. PMID:20042277

Caravelli, Alejandro H; Contreras, Edgardo M; Zaritzky, Noemí E

2010-05-15

414

Effect of base addition rate on the preparation of partially neutralized ferric chloride solutions  

Microsoft Academic Search

Cationic polymers prepared from partially neutralized ferric chloride solutions were investigated using photon correlation spectroscopy (PCS) techniques. To study the speciation and yield of the polymers, FeCl3 solutions were hydrolyzed by adding NaHCO3 solution for a range of hydrolysis ratios (B=[OH]\\/FeT) of 0 to 2.0 under different base addition rates. It was observed that the prepared solution has a higher

Ta-Kang Liu; Edward S. K. Chian

2005-01-01

415

Phosphorous removal in batch systems using ferric chloride in the presence of activated sludges  

Microsoft Academic Search

The objectives of this work were: (a) to analyze the effect of alkalinity, pH and initial Fe:P molar ratio (Fe0:P0) on the precipitation of orthophosphate using ferric chloride in the presence of activated sludge in order to represent conditions of simultaneous precipitation, and in exhausted wastewater to simulate conditions of post-precipitation, (b) to compare the experimental results with predictions obtained

Alejandro H. Caravelli; Edgardo M. Contreras; Noemí E. Zaritzky

2010-01-01

416

Sodium ferric gluconate complex in haemodialysis patients: a prospective evaluation of long-term safety  

Microsoft Academic Search

Background. A previous single dose placebo- controlled double-blinded trial showed an extremely low (0.4%) intolerance rate of sodium ferric gluconate complex (SFGC) in SFGC-naive haemodialysis patients. No large prospective trials have assessed the safety of SFGC during repeated exposure in the outpatient haemodialysis setting. Methods. Chronic haemodialysis patients complet- ing the single-dose trial of SFGC were eligible to participate in

Beckie Michael; Daniel W. Coyne; Vaughn W. Folkert; Naomi V. Dahl; David G. Warnock

417

A Critical Evaluation of the Effect of Sorbitol on the Ferric–Xylenol Orange Hydroperoxide Assay  

Microsoft Academic Search

Measurement of hydroperoxide concentration by the ferric–xylenol orange assay has the advantages of simplicity, convenience, and inertness to oxygen (Gay, C., et al. (1999) Anal. Biochem. 273, 149–155). However, its sensitivity is limited by the molar absorption coefficients, which are less than 50,000 M?1 cm?1 for most hydroperoxides. An earlier report showed that this could be significantly enhanced by the

Craig Gay; Janusz M. Gebicki

2000-01-01

418

Ferric-ferrous equilibria in natural silicate liquids at 1 bar  

Microsoft Academic Search

Ferric and ferrous iron concentrations have been measured in 57 silicate liquids equilibrated at temperatures (1,200°–1,330°C) above the liquidus and at oxygen fugacities close to those defined by quartz-fayalite-magnetite. The experimental results reported here span virtually the entire known compositional range of lavas. An empirical equation relating the mole fraction of Fe2O3 and FeO to oxygen fugacity, absolute temperature and

R. O. Sack; I. S. E. Carmichael; M. Rivers; M. S. Ghiorso

1981-01-01

419

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