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1

Nanophase iron oxides as a key ultraviolet sunscreen for ancient photosynthetic microbes  

NASA Astrophysics Data System (ADS)

We propose that nanophase iron-oxide-bearing materials provided important niches for ancient photosynthetic microbes on the Earth that ultimately led to the oxygenation of the Earth's atmosphere and the formation of iron-oxide deposits. Atmospheric oxygen and ozone attenuate ultraviolet 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 early and played a critical role in subsequent evolution. Of primary importance was protection below 290 nm, where peak nucleic acid (~260 nm) and protein (~280 nm) absorptions occur. Nanophase ferric oxide/oxyhydroxide minerals absorb, and thus block, the lethal ultraviolet radiation, while transmitting light through much of the visible and near-infrared regions of interest to photosynthesis (400 to 1100 nm). Furthermore, they were available in early environments, and are synthesized by many organisms. Based on experiments using nanophase ferric oxide/oxyhydroxide minerals as a sunscreen for photosynthetic microbes, we suggest that iron, an abundant element widely used in biological mechanisms, may have provided the protection that early organisms needed in order to be able to use photosynthetically active radiation while being protected from ultraviolet-induced damage. The results of this study are broadly applicable to astrobiology because of the abundance of iron in other potentially habitable bodies and the evolutionary pressure to utilize solar radiation when available as an energy source. This model could apply to a potential life form on Mars or other bodies where liquid water and ultraviolet radiation could have been present at significant levels. Based on ferric oxide/oxyhydroxide spectral properties, likely geologic processes, and the results of experiments with the photosynthetic organisms, Euglena sp. and Chlamydomonas 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.

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

2006-07-01

2

Modified electrochromism of tungsten oxide via platinum nanophases  

NASA Astrophysics Data System (ADS)

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 observed in optical properties during electrochemical reaction. The change of electrochromic properties in the Pt -WO3 is caused by modified structural and electrochemical properties of the WO3 by Pt metallic nanophases dispersed in the oxide matrix.

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

2006-05-01

3

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

4

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

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

1995-01-01

5

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

NASA Astrophysics Data System (ADS)

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.

1995-03-01

6

Airborne Density of Ferric Oxide Aggregate Microspheres  

Microsoft Academic Search

The density of ferric oxide particles produced by a spinning disc generator was measured with a Timbrell aerosol spectrometer, a Millikan oil drop apparatus, and a Thomas gravity settling tube. Using the Timbrell and Millikan equipment, the density was found to be 2.56?gm\\/cm.

ROBERT B. SPERTELL; MORTON LIPPMANN

1971-01-01

7

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

8

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

9

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

10

ADSORPTION OF TRACE METALS BY HYDROUS FERRIC OXIDE IN SEAWATER  

EPA Science Inventory

The adsorption of trace metals by amorphous hydrous ferric oxide in seawater is studied with reference to simple model systems designed to isolate the factors which may have an effect on the isotherms. Results show that the complex system behaves in a remarkably simple way and th...

11

ARSENATE SORPTION BY HYDROUS FERRIC OXIDE INCORPORATED ONTO GRANULAR ACTIVATED CARBON WITH PHENOL FORMALDEHYDE RESINS COATING  

Microsoft Academic Search

A simple and effective method was developed using phenol formaldehyde (PF) resins to immobilize hydrous ferric oxide (HFO) onto granular activated carbon (GAC). The resulting sorbent possesses advantages for both the ferric oxide and the GAC, such as a great As?affinity of ferric oxide, large surface area of GAC, and enhanced physical strength. The studies showed that within one hour

J. Ming Zhuang; E. Hobenshield; T. Walsh

2008-01-01

12

21 CFR 186.1300 - Ferric oxide.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

13

21 CFR 186.1300 - Ferric oxide.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

14

21 CFR 186.1300 - Ferric oxide.  

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

2014-04-01

15

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

16

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

PubMed Central

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

2014-01-01

17

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

NASA Astrophysics Data System (ADS)

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

Birkner, N.; Navrotsky, A.

2011-12-01

18

Photoelectrochemical oxidation of water at transparent ferric oxide film electrodes.  

PubMed

The fabrication of thin-film Fe(2)O(3) photoanodes from the spray pyrolysis of Fe(III)-containing solutions is reported along with their structural characterization and application to the photoelectrolysis of water. These films combine good performance, measured in terms of photocurrent density, with excellent mechanical stability. A full investigation into the effects that modifications of the spray-pyrolysis method, such as the addition of dopants or structure-directing agents and changes in precursor species or carrier solvent, have on the performance of the photoanodes has been realized. The largest photocurrents were obtained from photoanodes prepared from ferric chloride precursor solutions, simultaneously doped with Ti(4+) (5%) and Al(3+) (1%). Doping with Zn(2+) also shows promise, cathodically shifting the onset potential by approximately 0.22 V. PMID:16852715

Jorand Sartoretti, Chantal; Alexander, Bruce D; Solarska, Renata; Rutkowska, Iwona A; Augustynski, Jan; Cerny, Radovan

2005-07-21

19

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

20

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

21

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...

22

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

Microsoft Academic Search

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

N. Lazaroff; W. Sigal; A. Wasserman

1982-01-01

23

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

24

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...

25

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

PubMed

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

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

2010-10-01

26

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

Microsoft Academic Search

In the present work, ferric oxide nanonails were prepared by screen printing method on borosilicate glass substrate and their electrical and LPG sensing properties were investigated. The structural and morphological characterizations of the material were analyzed by means of X-ray diffraction (XRD) and Scanning electron microscopy (SEM). XRD pattern revealed crystalline ?-phase and rhombohedral crystal structure. SEM images show nanonails

B. C. Yadav; Satyendra Singh; Anuradha Yadav

2011-01-01

27

Nanophase catalytic oxides: I. Synthesis of doped cerium oxides as oxygen storage promoters  

Microsoft Academic Search

Doped CeO2 materials were synthesized with the aim to improve the performance of CeO2 as oxygen storage promoter in gas catalytic reactions. The coprecipitation method was used for the synthesis of fine oxalate precursors of high homogeneity and well defined composition. The chemical and morphological properties of both the coprecipitated oxalates and the calcined oxides were examined. The influence of

Yu Zhang; Sara Andersson; Mamoun Muhammed

1995-01-01

28

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

29

Sorption of Cadmium on Hydrous Ferric Oxide at High Sorbate/Sorbent Ratios: Equilibrium, Kinetics, and Modeling  

E-print Network

Sorption of Cadmium on Hydrous Ferric Oxide at High Sorbate/Sorbent Ratios: Equilibrium, Kinetics modelwithout addition of fittingparameters. The kinetics of cadmium sorptionslow considerablyasthesorbate existing data sets. In this paper we report on an experimental study of cadmium sorption on hydrous ferric

Morel, FranƧois M. M.

30

Soluble microbial products decrease pyrite oxidation by ferric iron at pH < 2.  

PubMed

Research on microbial activity in acid mine drainage (AMD) has focused on transformations of iron and sulfur. However, carbon cycling, including formation of soluble microbial products (SMP) from cell growth and decay, is an important biogeochemical component of the AMD environment. Experiments were conducted to study the interaction of SMP with soluble ferric iron in acidic conditions, particularly the formation of complexes that inhibit its effectiveness as the primary oxidant of pyrite during AMD generation. The rate of pyrite oxidation by ferric iron in sterile suspensions at pH 1.8 was reduced by 87% in the presence of SMP produced from autoclaved cells at a ratio of 0.3 mg DOC per mg total soluble ferric iron. Inhibition of pyrite oxidation by SMP was shown to be comparable to, but weaker than, the effect of a chelating synthetic siderophore, DFAM. Two computational models incorporating SMP complexation were fitted to experimental results. Results suggest that bacterially produced organic matter can play a role in slowing pyrite oxidation. PMID:23777272

Yacob, Tesfayohanes; Pandey, Sachin; Silverstein, Joann; Rajaram, Harihar

2013-08-01

31

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

32

Kinetic Study of Polyaniline Film Formation Using Ferric Chloride\\/Ammonium Persulfate as Composite Oxidant  

Microsoft Academic Search

Polyaniline (PANI) was synthesized by in situ emulsion polymerization. The kinetics of the PANI film formation was investigated by the quartz crystal microbalance technique (QCM). PANI film doped with dodecylbenzenesulfonic acid (DBSA) was synthesized by emulsion polymerization using ferric chloride\\/ammonium persulfate (FeCl3\\/APS) as composite oxidant in the presence of a constant (0.4 T) magnetic field (MF). The results showed that the

Wen-Yi Su; Feng-Yan Liang; Li Ma

2012-01-01

33

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

Microsoft Academic Search

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

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

2011-01-01

34

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

35

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

PubMed

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

Lazaroff, N; Sigal, W; Wasserman, A

1982-04-01

36

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 PMID:16345996

Lazaroff, Norman; Sigal, Warren; Wasserman, Andrew

1982-01-01

37

Formation of ferric oxides from aqueous solutions: A polyhedral approach by X-ray Absorption Spectroscopy: II. Hematite formation from ferric gels  

NASA Astrophysics Data System (ADS)

The evolution of the local structure around ferric ions has been followed through X-ray Absorption Spectroscopy (XAS) during the formation of hematite from ferric gels at 92°C. Fe K-edge structures and Extended X-ray Absorption Fine Structure (EXAFS) results confirm that ferric ions remain 6-fold coordinated during this process. A detailed study of the structural modifications involved has been conducted based on the analysis of the nearest and next-nearest Fe distances, which give access to the interpolyhedral relations at all stages of the evolution. Non-aged, freshly precipitated, hydrous gels possess a goethite/akaganeite-like local structure. During gel ? hematite transformation, an intermediate stage is indicated by a local structure which cannot be interpreted as a mixture of the initial gel and final hematite. This intermediate stage is stable between 1 and 6 hours ageing and is characterized by Feoctahedra joined by corners (d(Fe-Fe) = 3.43 Å) , edges (d(Fe-Fe) = 3.05 Å) , and faces (d(Fe-Fe) = 2.89 Å) . The local structure of this transient phase is similar to that of ferrihydrite and feroxyhite, but unlike these two oxides, it remains long-range disordered as XRD patterns display no hkl reflection. At 6 hours ageing, hematite is detected by EXAFS and XRD. Hematite crystallites develop at the expense of the gel, and after 130 hours at 92°C the transformation is completed. The transient configuration between the freshly precipitated gel and final hematite is an important step during the formation of Fe oxides in continental and marine environments. The appearance of facesharing octahedra within hydrous gels is thought to reduce the activation energy barrier of the ferric gel ? hematite transformation. The metastability of the natural gels, which possess a local structure similar to that of the transient phase, is explained by the role played by the impurities in inhibiting the dioctahedral reorganization of the framework and hence the formation of hematite.

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

1990-04-01

38

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

39

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

PubMed

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

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

2008-04-01

40

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 that increase the bioavailability of ferric iron. Recent work has suggested that both aqueous and solid-phase Mn(III) may affect siderophore-mediated iron transport, but scant information appears to be available about the potential roles of layer type manganese oxides, which are relatively abundant in soils and the oligotrophic marine water column. To probe the effects of layer type manganese oxides on the stability of aqueous Fe-siderophore complexes, we studied the sorption of ferrioxamine B [Fe(III)HDFOB +, an Fe(III) chelate of the trihydroxamate siderophore desferrioxamine B (DFOB)] to two synthetic birnessites [layer type Mn(III,IV) oxides] and a biogenic birnessite produced by Pseudomonas putida GB-1. We found that all of these predominantly Mn(IV) oxides greatly reduced the aqueous concentration of Fe(III)HDFOB + at pH 8. Analysis of Fe K-edge EXAFS spectra indicated that a dominant fraction of Fe(III) associated with the Mn(IV) oxides is not complexed by DFOB as in solution, but instead Fe(III) is specifically adsorbed to the mineral structure at multiple sites, thus indicating that the Mn(IV) oxides displaced Fe(III) from the siderophore complex. These results indicate that layer type manganese oxides, including biogenic minerals, may sequester iron from soluble ferric complexes. We conclude that the sorption of iron-siderophore complexes may play a significant role in the bioavailability and biogeochemical cycling of iron in marine and terrestrial environments.

Duckworth, Owen W.; Bargar, John R.; Sposito, Garrison

2008-07-01

41

Gold coated ferric oxide nanoparticles based disposable magnetic genosensors for the detection of DNA hybridization processes.  

PubMed

In this article, a disposable magnetic DNA sensor using an enzymatic amplification strategy for the detection of specific hybridization processes, based on the coupling of streptavidin-peroxidase to biotinylated target sequences, has been developed. A thiolated 19-mer capture probe was attached to gold coated ferric oxide nanoparticles and hybridization with the biotinylated target was allowed to proceed. Then, a streptavidin-peroxide was attached to the biotinylated target and the resulting modified gold coated ferric oxide nanoparticles were captured by a magnetic field on the surface of a home-made carbon screen printed electrode (SPE). Using hydroquinone as a mediator, a square wave voltammetric procedure was chosen to detect the hybridization process after the addition of hydrogen peroxide. Different aspects concerning the assay protocol and nanoparticles fabrication were optimized in order to improve the sensitivity of the developed methodology. A low detection limit (31 pM) with good stability (RSD=7.04%, n=10) was obtained without the need of polymerase chain reaction (PCR) amplification. PMID:20951565

Loaiza, Óscar A; Jubete, Elena; Ochoteco, Estibalitz; Cabańero, German; Grande, Hans; Rodrķguez, Javier

2011-01-15

42

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

43

Platinum-CatalyzedOxidations of Organic Compounds by Ferric Sulfate: Use of a Redox Fuel Cell to Mediate Complete Oxidation of  

E-print Network

Platinum-CatalyzedOxidations of Organic Compounds by Ferric Sulfate: Use of a Redox Fuel Cell to Mediate Complete Oxidation of Ethylene Glycol by Dioxygen at 80Ā°C Christopher B. Gorman, Steven H. Bergens January 17,1995; revised July 28, 1995 A number of alcohols,aldehydes, and carboxylicacids were oxidized

Prentiss, Mara

44

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

45

Formation of Green Rust and Immobilization of Nickel in Response to Bacterial Reduction of Hydrous Ferric Oxide  

SciTech Connect

This investigation documents the formation of Green Rust (GR) and immobilization of Ni2+ in response to bacterial reduction of hydrous ferric oxide (HFO) reduction experiments provided evidence that the solid-phase partitioning of Ni2+ in GR extended from equilibrium solid-solution behavior.

Parmar, N.; Gorby, Yuri A.; Beveridge, Terrance J.; Ferris, F G.

2001-04-01

46

Characterization of nanophase Al-oxide/Al powders by electron energy-loss spectroscopy.  

PubMed

Al nanoparticles were prepared by the inert gas condensation method. After passivation with oxygen and air exposure we obtained a powdered sample of an Al-oxide/Al nanocomposite material. In the present paper we describe the use of the electron energy-loss spectroscopy (EELS) technique in a transmission electron microscope to characterize such nanostructured powders compared with a microcrystalline commercial aluminium foil. Energy-filtered images showed the presence of an alumina overlayer of approximately 4 nm covering the aluminium nanoparticles (23 nm in diameter). EELS analysis enabled us to determine the total amount of Al2O3 and metallic Al and the structure of the alumina passivation overlayer in the sample. In particular, the extended energy-loss fine structure analysis of the data showed a major presence of Al tetrahedrally coordinated with oxygen in the alumina passivation layer of Al nanoparticles instead of the octahedral coordination found for a conventional Al foil. This surprising effect has been attributed to the nanoscopic character of the grains. The analysis of the electron-loss near-edge structure also determines the presence of a certain degree of aggregation in this kind of powdered sample as result of the coalescence of the nanocrystalline grains. The procedure presented here may have the potential to solve other problems during characterization of nanostructured materials. PMID:9767485

Fernįndez; Sįnchez-López; Caballero; Martin; Vacher; Ponsonnet

1998-08-01

47

Surface modification of bio?carrier by plasma oxidation?ferric ions coating technique to enhance bacterial adhesion  

Microsoft Academic Search

A novel technique was developed to mask the positive charge conferred to the support surface, thanks to low?temperature plasma oxidation, and followed by ferric ions coating. The oxidation strength of various plasma, such as CO2, O2, NH3 and Ar were studied for four kinds of thermoplastic supports (PE, PP, PS, PVC). A general increase in surface hydrophilicity in term of

Yu Liu

1996-01-01

48

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

PubMed Central

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

Wang, Yun; Newman, Dianne K.

2009-01-01

49

Indirect spectrophotometric determination of arbutin, whitening agent through oxidation by periodate and complexation with ferric chloride  

NASA Astrophysics Data System (ADS)

A simple and accurate spectrophotometric method for the determination of arbutin (glycosylated hydroquinone) is described. It is based on the oxidation of arbutin by periodate in presence of iodate. Excess periodate causes liberation of iodine at pH 8.0. The unreacted periodate is determined by measurement of the liberated iodine spectrophotometrically in the wavelength range (300-500 nm). A calibration curve was constructed for more accurate results and the correlation coefficient of linear regression analysis was -0.9778. The precision of this method was better than 6.17% R.S.D. ( n = 3). Regression analysis of Bear-Lambert plot shows good correlation in the concentration range 25-125 ug/ml. The identification limit was determined to be 25 ug/ml a detailed study of the reaction conditions was carried out, including effect of changing pH, time, temperature and volume of periodate. Analyzing pure and authentic samples containing arbutin tested the validity of the proposed method which has an average percent recovery of 100.86%. An alternative method is also proposed which involves a complexation reaction between arbutin and ferric chloride solution. The produced complex which is yellowish-green in color was determined spectophotometrically.

Barsoom, B. N.; Abdelsamad, A. M. E.; Adib, N. M.

2006-07-01

50

Spectroscopic characterization of nitrosylheme in nitric oxide complexes of ferric and ferrous cytochrome c' from photosynthetic bacteria.  

PubMed

Reactions of ferric and ferrous cytochromes c' from four photosynthetic bacteria (Rhodobacter capsulatus ATCC 11166, Rhodopseudomonas palustris ATCC 17001, Rhodospirillum rubrum ATCC 11170, and Chromatium vinosum ATCC 17899) with nitric oxide have been investigated by electronic absorption and electron paramagnetic resonance spectroscopies. The heme iron(III) of these ferric cytochromes c' has been recently reported to be in a quantum mechanically admixed (S = 5/2, 3/2) state [Fujii, S., Yoshimura, T., Kamada, H., Yamaguchi, K., Suzuki, S., Shidara, S. and Takakuwa, S. (1995) Biochim. Biophys. Acta 1251, 161-169]. The affinity of ferric cytochromes c' for NO among these bacterial species (C. vinosum > Rps. palustris approximately Rb. capsulatus > R. rubrum) was apparently related to the S = 3/2 content in the or der. In the reaction of ferrous cytochrome c' with NO, six- and five-coordinated nitrosylhemes, which represent species with and without a ligand at the axial position trans to nitrosyl group, have been formed. The content of six-coordinated nitrosylheme in NO-ferrous cytochrome c' has been determined to be Rb. capsulatus approximately Rps. palustris > C. vinosum < R rubrum, suggesting that a stability of iron-to-histidine bond decreases with this order. The NO reactions of ferric and ferrous cytochromes c' from photosynthetic bacteria have been compared with those of cytochromes c' from denitrifying bacteria. PMID:8547347

Yoshimura, T; Fujii, S; Kamada, H; Yamaguchi, K; Suzuki, S; Shidara, S; Takakuwa, S

1996-01-01

51

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

Microsoft Academic Search

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

Jennifer A Wilkie; Janet G Hering

1996-01-01

52

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

NASA Astrophysics Data System (ADS)

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

Holmes, Paul R.; Crundwell, Frank K.

2000-01-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

54

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

PubMed

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

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

2014-02-01

55

Thermodynamic stabilization of hydrous ferric oxide by adsorption of phosphate and arsenate.  

PubMed

Hydrous ferric oxide (HFO) is an X-ray amorphous compound with a high affinity for anions under strongly or mildly acidic conditions. Because of the usually small particle size of HFO, the adsorption capacity is high and adsorption may significantly impact the thermodynamic properties of such materials. Here we show that adsorption of phosphate and arsenate stabilizes HFO by experimental determination of enthalpies of formation (by acid-solution calorimetry) and estimates of standard entropies for six phosphate- or arsenate-enriched HFO samples. At pH values lower than ?5, the phosphate-doped HFO is not only less soluble than ferrihydrite (anion-free HFO) but also crystalline FeOOH polymorphs feroxyhyte and lepidocrocite. The arsenate-doped HFO is also stabilized with respect to the ferrihydrite. Phosphate availability in soils can be controlled by the phosphate-enriched HFO which is many orders of magnitude less soluble than apatite or crystalline Fe(III) phosphates, for example strengite (FePO(4)·2H(2)O). Thermodynamic dissolution models for scorodite (FeAsO(4)·2H(2)O) and As-enriched HFO show that under mildly acidic or circumneutral conditions, scorodite dissolves, As-HFO precipitates, and a substantial amount of As(V) is released into the aqueous solution (at pH 7, log m(As) ? -2.5). The data presented in this paper can be used to model the equilibrium concentration of Fe(III), P(V), or As(V) in soil solutions or in natural or anthropogenic sediments polluted by arsenic. PMID:21557572

Majzlan, Juraj

2011-06-01

56

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

Microsoft Academic Search

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

Paul R. Holmes; Frank K. Crundwell

2000-01-01

57

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

58

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

59

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

60

doi:10.1016/S0016-7037(03)00096-6 ATR-FTIR spectroscopic studies of boric acid adsorption on hydrous ferric oxide  

E-print Network

doi:10.1016/S0016-7037(03)00096-6 ATR-FTIR spectroscopic studies of boric acid adsorption to investigate mechanisms of boric acid (B(OH)3) and borate (B(OH)4 ) adsorption on hydrous ferric oxide (HFO). On the HFO surface, boric acid adsorbs via both physical adsorption (outer-sphere) and ligand exchange (inner

Sparks, Donald L.

61

Protective effects of fucoxanthin against ferric nitrilotriacetate-induced oxidative stress in murine hepatic BNL CL.2 cells.  

PubMed

Fucoxanthin is a carotenoid that is rich in some seaweed. Although fucoxanthin has been reported to possess radical-scavenging activities in vitro, little is known whether it may protect against iron-induced oxidative stress in cultured cells. In this study, we examined the protection of fucoxanthin against oxidative damage in BNL CL.2 cells induced by ferric nitrilotriacetate (Fe-NTA). The data show that incubation of BNL CL.2 cells with Fe-NTA for 30 min significantly decreased cell proliferation, whereas pretreatment with fucoxanthin (1-20 ??) for 24h significantly recovered cell proliferation in a dose-dependent manner. In addition, fucoxanthin pretreatment significantly decreased intracellular reactive oxygen species (ROS) and DNA damage in BNL CL.2 cells incubated with Fe-NTA for 30 min. Moreover, fucoxanthin markedly decreased the level of thiobarbituric acid-reactive substances (TBARS) and protein carbonyl contents in BNL CL.2 cells induced by Fe-NTA. By contrast, fucoxanthin significantly increased the levels of GSH in a concentration-dependent manner. These results demonstrate that fucoxanthin at 1-20?? effectively prevents cytotoxicity in BNL CL.2 cells treated with Fe-NTA, and that the protective effect is likely associated with decreased intracellular ROS, TBARS, protein carbonyl contents and increased GSH levels. PMID:21569835

Liu, Cheng-Ling; Liang, Ai-Ling; Hu, Miao-Lin

2011-10-01

62

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 0.005-400 µM, with a detection limit of 0.005 µM for acetylcholine. The biosensor measured plasma acetylcholine in apparently healthy and persons suffering from Alzheimer's disease. The enzyme electrode was unaffected by a number of serum substances but lost 50% of its initial activity after its 100 uses over a period of 3 months, when stored at 4°C. PMID:24836212

Chauhan, Nidhi; Pundir, C S

2014-11-15

63

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

SciTech Connect

Dissimilatory metal-reducing bacteria (DMRB) facilitate the reduction of Fe and Mn oxides in anoxic soils and sediments and play an important role in the cycling of these metals and other elements such as carbon in aqueous environments.

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

2003-04-01

64

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

PubMed Central

Ammonium was shown to be a limiting nutrient for iron oxidation in cultures of Thiobacillus ferrooxidans. In addition, one strain was also able to assimilate nitrate, but not nitrite, for growth and coupled iron oxidation. Some amino acids (0.5 mM) were tested as a source of nitrogen; none clearly stimulated bacterial activity and inhibition was commonly encountered. Complex nitrogenous compounds were inhibitory at high concentrations (0.1 to 0.5%, wt/vol) and, at low concentrations, some clearly stimulated the bacterial iron oxidation in ammonium-limited cultures. Enhancement of iron oxidation by these compounds was also observed in ammonium-unlimited cultures, suggesting their possible role in providing trace nutrients and possibly carbon for the bacteria. PMID:16345391

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

1979-01-01

65

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

SciTech Connect

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

Wielinga, B.; B. Bostick; R.F. Rosenzweig; S. Fendorf

2000-05-15

66

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

PubMed

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

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

2011-01-01

67

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

68

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

69

Influence of zinc-oxide eugenol, formocresol, and ferric sulfate on bond strength of dentin adhesives to primary teeth.  

PubMed

This study evaluated in vitro the influence of a temporary filling {zinc oxide-eugenol (ZOE)} and two pulpotomy agents {formocresol (FC) and ferric sulfate (FS)} on shear bond strength (SBS) of two dentin adhesives to the dentin of primary molars. A total of 80 dentin surfaces were prepared and randomly allocated into 10 groups of 8 specimens each. Groups were subjected to different treatments, which included covering with a paste of ZOE mixed at different powder:liquid (P:L) ratios, placement on a gauze soaked in FC or FS, or they received no pretreatment and served as a control. XRV Herculite composite cylinders were bonded to dentin surfaces using Prime and Bond NT adhesive resin or Opti Bond Solo Plus adhesive resin. SBSs were determined using the lnstron testing machine running at a crosshead speed of 0.5 mm/min. The use of ZOE mixed at the lower P:L ratio of 10g:2g significantly decreased the values of SBS of the two adhesives. The use of two pulpotomy agents (FC and FS) significantly decreased the SBS of the two adhesives. The bond strength to dentin of primary teeth was influenced by the pulpotomy agents used and the ZOE P:L ratio but not by the adhesive system used. PMID:16127468

Salama, Fouad Saad

2005-08-15

70

Indirect spectrophotometric determination of arbutin, whitening agent through oxidation by periodate and complexation with ferric chloride  

Microsoft Academic Search

A simple and accurate spectrophotometric method for the determination of arbutin (glycosylated hydroquinone) is described. It is based on the oxidation of arbutin by periodate in presence of iodate. Excess periodate causes liberation of iodine at pH 8.0. The unreacted periodate is determined by measurement of the liberated iodine spectrophotometrically in the wavelength range (300–500nm).A calibration curve was constructed for

B. N. Barsoom; A. M. E. Abdelsamad; N. M. Adib

2006-01-01

71

Zinc immobilization and magnetite formation via ferric oxide reduction by Shewanella putrefaciens 200  

SciTech Connect

Long-term batch experiments in an artificial groundwater medium indicated that microbial reduction of synthetic, high-surface-area goethite and lepidocrocite by Shewanella putrefaciens 200 can act to immobilize surface-associated zinc into a new mineral phase that is not soluble in 0.5 M HCl. While Zn was incorporated in siderite grains in experiments with goethite, additional Zn immobilization may result from incorporation into as yet unidentified biogenic minerals or into a more crystalline goethite. Experiments with an oxide mixture primarily composed of lepidocrocite resulted in the production of magnetite, biphasic immobilization of Zn, and an enhanced overall degree of Zn immobilization. When NO{sub 3}{sup {minus}} was present as an alternate electron acceptor, microbial production of Fe(II) was inhibited, and the degree of Zn immobilization was subsequently reduced. These data indicate that (i) biologically induced mineralization can play a key role in the cycling of trace elements in natural systems, (ii) the nature of the oxide surface plays an important role in biologically induced mineralization, and (iii) conditions associated with Fe(II) production are necessary for these processes to immobilize surface-bound Zn within these new mineral phases.

Cooper, D.C.; Picardal, F.; Rivera, J.; Talbot, C.

2000-01-01

72

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

NASA Astrophysics Data System (ADS)

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

Majzlan, Juraj; Lalinskį, Bronislava; Chovan, Martin; Jurkovi?, L.'ubomķr; Milovskį, Stanislava; Göttlicher, Jörg

2007-09-01

73

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

74

21 CFR 184.1297 - Ferric chloride.  

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

2014-04-01

75

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

NASA Astrophysics Data System (ADS)

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

Wood, Bernard J.; Virgo, David

1989-06-01

76

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

77

Hardfacing of Bulk Nanophase Coatings  

NASA Astrophysics Data System (ADS)

This paper discusses the production of iron-based nanophase hardfaced coatings by means of common arc welding methods. The key is the exact, close-to-eutectic composition of the newly developed alloys. In combination with a precise control of the dilution of the base metal, this results in an eutectic composition of the coating, which allows the in-situ generation of nanoscale hardphases during solidification. The applied cooling rates are only of secondary importance. The self-organizing nanophase structures within the hardfaced coatings show phase dimensions of approximately 100-300 nm. The generation of nanoscale structures in hardfaced coatings allows the improvement of mechanical properties, wear resistance and corrosion resistance. The article further demonstrates a potential application for these types of hardfaced coatings in the field of cutting edges.

Reisgen, Uwe; Balashov, Boris; Stein, Lars; Geffers, Christoph

2012-01-01

78

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

79

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

Microsoft Academic Search

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

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

2011-01-01

80

alpha-Tocopherol (vitamin-E) ameliorates ferric nitrilotriacetate (Fe-NTA)-dependent renal proliferative response and toxicity: diminution of oxidative stress.  

PubMed

Ferric nitrilotriacetate (Fe-NTA) is a potent nephrotoxic agent. In this communication, we show the modulatory effect of DL-alpha-tocopherol (Vitamin-E) on ferric nitrilotriacetate (Fe-NTA)-induced renal oxidative stress, toxicity and hyperproliferative response in rats. Fe-NTA-treatment enhances the susceptibility of renal microsomal membrane for iron-ascorbate-induced lipid peroxidation and hydrogen peroxide generation which are accompanied by a decrease in the activities of renal antioxidant enzymes, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase and depletion in the level of renal glutathione. Parallel to these changes, a sharp increase in blood urea nitrogen and serum creatinine has been observed. In addition, Fe-NTA-treatment also enhances renal ornithine decarboxylase activity (ODC) and increases [3H]thymidine incorporation in renal DNA. Prophylactic treatment of animals with Vit.E daily for 1 week prior to the administration of Fe-NTA resulted in the diminution of Fe-NTA-mediated damage. Enhanced susceptibility of renal microsomal membrane for lipid peroxidation induced by iron-ascorbate and hydrogen peroxide generation were significantly reduced (P < 0.05). In addition, the depleted level of glutathione and inhibited activities of antioxidant enzymes recovered to significant levels (P < 0.05). Similarly, the enhanced blood urea nitrogen and serum creatinine levels which are indicative of renal injury showed a reduction of about 50% at a higher dose of Vit.E. The pretreatment of rats with Vit.E reduced the Fe-NTA-mediated induction in ODC activity and enhancement in [3H]thymidine incorporation in DNA. The protective effect of Vit.E was dose dependent. In summary, our data suggest that Vit.E is an effective chemopreventive agent in kidney and may suppress Fe-NTA-induced renal toxicity. PMID:9587785

Iqbal, M; Rezazadeh, H; Ansar, S; Athar, M

1998-03-01

81

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

82

Ferric Carboxymaltose Injection  

MedlinePLUS

... kidneys to stop working) who are not on dialysis. Ferric carboxymaltose injection is in a class of ... nausea; cold, clammy skin; rapid, weak pulse; chest pain; or loss of consciousness. If you experience a ...

83

Do grain boundaries in nanophase metals slide?  

SciTech Connect

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

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

2006-10-27

84

Labeling of the pathogenic bacterium Staphylococcus aureus with gold or ferric oxide-core nanoparticles highlights new capabilities for investigation of host-pathogen interactions.  

PubMed

Throughout the world, infections caused by bacteria such as Staphylococcus aureus are a major cause of morbidity and mortality. In order to gain some understanding of the complicated physiological link between host and pathogen, modern techniques such as confocal microscopy and sophisticated OMICs technologies are suitable. However, labeling of pathogens such as S. aureus with green fluorescent protein, for example, or the generation of a reliable antibody, which are prerequisites for the application of reproducible isolation techniques, does not always succeed. Here, we present a universal approach for monitoring pathogen traffic after internalization into host cells by fluorescence microscopy and for isolation of bacteria from host-pathogen interaction assays using gold or ferric oxide-core, poly(vinyl alcohol) coated, and fluorescence-labeled nanoparticles (NP). The incubation of S. aureus HG001 with those NP had only minor effects on the bacterial growth in vitro. Quantitative proteome analysis after 24 h of NP incubation revealed that presence of NP provoked only marginal changes in the proteome pattern. The method presented enabled us to investigate the behavior of S. aureus HG001 during infection of S9 human epithelial cells by means of fluorescence microscopy and proteomics using magnetic separation or cell sorting. PMID:24347542

Depke, Maren; Surmann, Kristin; Hildebrandt, Petra; Jehmlich, Nico; Michalik, Stephan; Stanca, Sarmiza E; Fritzsche, Wolfgang; Völker, Uwe; Schmidt, Frank

2014-02-01

85

Low electrical potential anode modified with Fe/ferric oxide and its application in marine benthic microbial fuel cell with higher voltage and power output  

NASA Astrophysics Data System (ADS)

Low voltage and power output limit the widespread application of marine benthic microbial fuel cell (BMFCs). To increase the cell power, a Fe/Ferric oxide modified anode fabricating by electrolytic deposition is reported here. The novel anode has a lower surface contact angle and higher wettability, which favors the adhesion of bacteria. It is firstly demonstrated that the electrical potential of the modified anode is about -775 mV, much lower than that of the plain graphite (about -450 mV). Open circuit potential of BMFC with the modified anode is about 1050 ± 50 mV, while the potential for the plain cells is only 700 ± 50 mV. In comparison with the plain graphite, the modified anode presents a 393-fold exchange current density and a higher kinetic activity. The output power reaches 7.4 × 10-2 mW cm-2, 17.4-fold higher than that of the plain graphite. A composite mechanism of both chemical and microbial enhancement of the modified anode is proposed to explain its excellent electrochemical performance. The modified anode has potential for high-power output cell and novel voltage-booster design to make the BMFC utilization feasibility.

Fu, Yubin; Xu, Qian; Zai, Xuerong; Liu, Yuanyuan; Lu, Zhikai

2014-01-01

86

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. PMID:10543817

Caccavo, Frank

1999-01-01

87

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

NASA Astrophysics Data System (ADS)

A group of small springs that are informally called "Orange Spring", located near Hakereteke Stream in the northern part of the Waiotapu geothermal area, feed hot (˜ 80 °C), acidic (pH: 2.1 - 2.4), As-rich sulfate waters into a discharge channel that is up to 25 cm deep. Submerged reddish-brown precipitates on the channel floor are formed largely of noncrystalline As-rich hydrous ferric oxide (HFO: mainly goethite), poorly crystalline lepidocrocite, and crystalline jarosite. Well-preserved coccoid and rod-shaped microbes are found in the As-rich HFO, but not in the lepidocrocite or jarosite. The jarosite was probably precipitated when the water had a low pH (< 3) and high SO 4 content, whereas the goethite and lepidocrocite were probably precipitated when the water had a slightly higher pH (> 4) and lower SO 4 content. The fluctuations in the pH and SO 4 content, which led to precipitation of the different mineral phases, may reflect mixing of the spring water with stream water that flowed through the channel when Hakereteke Stream was in flood stage. The goethite probably formed when coccoid and rod-shaped bacteria ( Acidithiobacillus ferrooxidans?) mediated rapid oxidization of the Fe 2+ to Fe 3+ that was then immediately coprecipitated with the As. Such rapid precipitation promoted mineralization of the microbes. The lack of mineralized microbes and the lower As in the lepidocrocite and jarosite may reflect precipitation rates that were slower than the decay rates of the microbes, or ecological factors that limited their growth.

Jones, Brian; Renaut, Robin W.

2007-01-01

88

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

NASA Astrophysics Data System (ADS)

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).

Refat, Moamen S.

2014-12-01

89

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

90

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

PubMed

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

Azam, Hossain M; Finneran, Kevin T

2013-01-01

91

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

Microsoft Academic Search

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

Annika Pohl; Gunnar Westin; Kjell Jansson

2003-01-01

92

Nanophase diamond films produced by laser deposition  

NASA Astrophysics Data System (ADS)

Films of nanophase diamond can be prepared in vacuum by the laser ablation of graphite at intensities in excess of 1011 W cm-2. A variety of structural morphologies can result that depend upon the kinetic energies and charge states employed. The most promising is a nanophase diamond that we originally termed `amorphic diamond.' It is composed of nanometer scale nodules of sp3 bonded carbon. The high energy of condensation from the laser plasma source provides both for the chemical bonding of such films to a wide variety of substrates and for low values of residual compressive stress, 0.6 - 0.8 GPa. This paper reports the solution of a lingering problem with the hardness of nanophase diamond. The packing density of nodules in the finished ceramic depends upon process variables and so hardness can fluctuate. With critical control at the point of ablation, films are produced that are too hard to measure. In this work, raw data produced with an advanced nanoindentation technique was analyzed with the conventional procedure and a hardness value of 125 GPa was obtained. Exceeding the hardness of natural diamond this value was so large as to raise concern for the validity of the conventional model used to interpret data. To avoid model dependent interpretation, a differential loading pressure, independent of depth, was used to give a lower limit on the hardness directly from the raw data. Comparable values of this lower limit, near 75 GPa have been measured on crystalline diamond prepared by CVD and on nanophase diamond deposited by our laser plasma method. The combination of hardness and resiliency together with a coefficient of friction near 0.1, seems to make nanophase diamond an attractive coating for use in current industrial applications.

Collins, Carl B., Jr.; Davanloo, Farzin; You, J. H.; Park, H.

1994-08-01

93

Synthesis of green rusts by oxidation of Fe(OH) 2, their products of oxidation and reduction of ferric oxyhydroxides; E-pH Pourbaix diagrams  

NASA Astrophysics Data System (ADS)

Fe II-Fe III hydroxysalt green rusts (GR), {?{?˜(m/n)HO}(1/3)-, are prepared by oxidising a Fe(OH) 2 precipitate in presence of anions A(Cl,SO42-,CO32-). Electrode potential E and pH recorded during aerial oxidation depend on the initial ratio R={[OH]/[Fe]}. For R=R=2, i.e. Fe(OH) 2 stoichiometry, two stages are observed and magnetite Fe 3O 4 forms. In contrast, an excess of Fe 2+ ions, i.e. Roxidation by H 2O 2, dry oxidation or voltammetry lead to deprotonated GR whereas bioreduction yields deprotonated {?[ fougerite with x?[1/3,2/3]. E-pH diagrams for hydroxycarbonate, chloride, or sulphate are presented. To cite this article: J.-M.R. Génin et al., C. R. Geoscience 338 (2006).

Génin, Jean-Marie R.; Ruby, Christian; Géhin, Antoine; Refait, Philippe

2006-06-01

94

Synthesis of green rusts by oxidation of Fe(OH) 2, their products of oxidation and reduction of ferric oxyhydroxides; E h –pH Pourbaix diagrams  

Microsoft Academic Search

FeII–FeIII hydroxysalt green rusts (GR), {FeII2\\/3FeIII1\\/3(OH)2}(1\\/3)+?{[(1\\/3)\\/n]An???(m\\/n)H2O}(1\\/3)?, are prepared by oxidising a Fe(OH)2 precipitate in presence of anions An?(Cl?,SO42?,CO32?). Electrode potential Eh and pH recorded during aerial oxidation depend on the initial ratio R={[OH?]\\/[FeII]}. For R=Rh=2, i.e. Fe(OH)2 stoichiometry, two stages are observed and magnetite Fe3O4 forms. In contrast, an excess of Fe2+ ions, i.e. RRh, gives rise to 3 stages

Jean-Marie R. Génin; Christian Ruby; Antoine Géhin; Philippe Refait

2006-01-01

95

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

96

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. PMID:19337418

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

2008-01-01

97

Supramolecular Nanophases and Templating: Bone, Semiconductors and Magnets  

NASA Astrophysics Data System (ADS)

Organic molecules can be programmed for self assembly of supramolecular nanophases that mimic the architecture of proteins and protein complexes. These structures can be the building blocks of new materials leading us to a fresh chapter on structure-function correlation in soft matter. Competing interactions among discrete nanostructures leads to unexpected order parameters and dynamics during self-assembly. Furthermore, organic nanophases offer the possibility of templating the size scales, shapes, and orientation of inorganic phases and polymers. Templating can occur on the surfaces of supramolecular nanophases or in confined compartments of the nanophases. One of the examples to be described in this lecture is the formation of nanofibers by self-assembly from specially designed block molecules in water. These nanofibers can nucleate hydroxyapatite nanocrystals recreating the nanoscale organization of bone, or can be designed to nucleate magnetic nanocrystals. In a different example templating of conducting polymers in cylindrical micelles is shown to result in important properties for organic electronic devices.

Stupp, Samuel

2003-03-01

98

Superhard nanophase materials for rock drilling applications  

SciTech Connect

Diamond Materials Incorporated is developing new class of superhard materials for rock drilling applications. In this paper, we will describe two types of superhard materials, (a) binderless polycrystalline diamond compacts (BPCD), and (b) functionally graded triphasic nanocomposite materials (FGTNC). BPCDs are true polycrystalline diamond ceramic with < 0.5 wt% binders and have demonstrated to maintain their wear properties in a granite-log test even after 700{degrees}C thermal treatment. FGTNCs are functionally-graded triphasic superhard material, comprising a nanophase WC/Co core and a diamond-enriched surface, that combine high strength and toughness with superior wear resistance, making FGTNC an attractive material for use as roller cone stud inserts.

Sadangi, R.K.; Voronov, O.A.; Tompa, G.S. [Diamond Materials Inc., Pisctaway, NJ (United States); Kear, B.H. [Rutgers Univ., Piscataway, NJ (United States)

1997-12-31

99

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

100

Molecular Structure of Ferric chloride  

NSDL National Science Digital Library

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

2002-08-27

101

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

102

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

E-print Network

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

Konhauser, Kurt

103

ESTCP DEMONSTRATION OF A BIOAVAILABLE FERRIC IRON TEST KIT  

EPA Science Inventory

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

104

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...

105

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2013 CFR

...occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron...Reg. No. 10025-77-1) is readily formed when ferric chloride is exposed to moisture...Prior sanctions for this ingredient different from the uses established in this...

2013-04-01

106

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2012 CFR

...occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron...Reg. No. 10025-77-1) is readily formed when ferric chloride is exposed to moisture...Prior sanctions for this ingredient different from the uses established in this...

2012-04-01

107

21 CFR 184.1297 - Ferric chloride.  

Code of Federal Regulations, 2011 CFR

...occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride hexahydrate (iron...Reg. No. 10025-77-1) is readily formed when ferric chloride is exposed to moisture...Prior sanctions for this ingredient different from the uses established in this...

2011-04-01

108

Ferric reductases or flavin reductases?  

Microsoft Academic Search

Assimilation of iron by microorganisms requires the presence of ferric reductases which participate in the mobilization of iron from ferrisiderophores. The common structural and catalytic properties of these enzymes are described and shown to be identical to those of flavin reductases. This strongly suggests that, in general, the reduction of iron depends on reduced flavins provided by flavin reductases.

Marc Fontecave; Jacques Covčs; Jean-Louis Pierre

1994-01-01

109

Hydrogen Reduction of Ferric Ions for Use in Copper Electrowinning  

SciTech Connect

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

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

2005-01-01

110

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

111

Access of ligands to the ferric center in lipoxygenase-1.  

PubMed Central

A form of ferric lipoxygenase-1 has been isolated that gives an EPR spectrum that is dominated by a species of intermediate rhombicity (E/D = 0.065). This species is obtained in the presence of a number of buffers of high concentration and in the absence of fatty acid byproducts of the iron oxidation. The species is unstable over a period of one day with respect to symmetry of the iron. The EPR lineshapes of the unstable species are highly sensitive to the anionic composition of the buffer and to the addition of neutral ligands. These results suggest that newly formed ferric lipoxygenase has weak affinity for a number of ligands. Affinity of charged ligands for the iron center may provide a mechanism for charge compensation as the iron center alternates between ferric and ferrous in the catalytic cycle. We use spectral simulation to evaluate quantitatively the interaction of the ferric center with ligands and also show that a transition in the middle Kramers doublet makes a significant contribution to the EPR spectrum of the more rhombic species. PMID:8386016

Gaffney, B J; Mavrophilipos, D V; Doctor, K S

1993-01-01

112

Structure and properties of nanophase WC\\/Co\\/VC\\/TaC hardmetal  

Microsoft Academic Search

A new approach to produce nanophase WC\\/Co\\/VC\\/TaC powder was developed by thermochemical processing method for improving the mechanical properties. To overcome coarsening and abnormal grain growth of the WC particles for nanophase WC\\/Co during the sintering, VC\\/TaC, VC, and TaC are used as the grain growth inhibitors by mechanical and chemical process. Nanophase WC\\/Co doped VC and VC\\/TaC by mechanical

B. K. Kim; G. H. Ha; G. G. Lee; D. W. Lee

1997-01-01

113

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

114

New Mesogenes Forming Nanophase Separated Liquid Crystalline Structure - Cubic Phase -  

Microsoft Academic Search

Hydrogen bonded complexes between 4-(oligodimethylsiloxyl)alkoxy benzoic acids and 4,4?-dipyridyl were found to exhibit a thermotropic liquid crystalline cubic phase. One of the important factors to realize the cubic structure could be the incompatibility between the flexible, bulky siloxane moiety and the rigid mesogenic core, which probably causes nanophase separation. We have investigated benzoic acid derivatives having a polar, relatively rigid

Etsushi Nishikawa; Jun Yamamoto; Hiroshi Yokoyama; Edward T. Samulski

2001-01-01

115

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

116

New nanophase iron-based catalysts for hydrocracking applications  

SciTech Connect

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

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

1994-11-01

117

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

118

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

E-print Network

of surface reactivity, by an ultrasound-driven decomposition of iron pentacarbonyl in Decalin mediumUltrasound Driven Deposition and Reactivity of Nanophasic Amorphous Iron Clusters with Surface. Revised Manuscript Received August 6, 1997X Aggregates of nanophasic amorphous iron particles in the size

Prozorov, Ruslan

119

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

120

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

NASA Astrophysics Data System (ADS)

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

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

1995-03-01

121

21 CFR 73.2299 - Ferric ferrocyanide.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

122

SO2 removal with ferric sulfate solution.  

PubMed

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

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

2008-04-01

123

21 CFR 73.2299 - Ferric ferrocyanide.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

124

21 CFR 73.2299 - Ferric ferrocyanide.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

125

21 CFR 73.2299 - Ferric ferrocyanide.  

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

2014-04-01

126

21 CFR 73.2299 - Ferric ferrocyanide.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

127

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

128

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

129

Nickel hydroxide and other nanophase cathode materials for rechargeable batteries  

NASA Astrophysics Data System (ADS)

The staff of US Nanocorp, Inc. are developing unique nanostructured materials for a wide range of applications in the areas of energy storage (batteries and ultracapacitors) and energy conversion (fuel cells and thermoelectric) devices. Many of the preparations of these materials exploit a wet synthesis process (patent pending) that is scaleable to large volume manufacturing and anticipated to be low in cost. Specifically, both the ?-form of nickel hydroxide and the hollandite form of manganese dioxide have been synthesized. The hexagonal Ni(OH) 2 is anticipated to significantly boost energy densities in nickel-alkaline batteries, including nickel/cadmium, nickel/metal hydride and nickel/zinc. The nanophase MnO 2 microstructure exhibits an unusual tunnelled tubular geometry within a 'bird's nest' superstructure, and is expected to be of interest as an intercalation cathode material in lithium-ion systems as well as a catalyst for fuel cells. Characterization of these materials has been by the techniques of high resolution SEM and TEM, as well as XRD. Both Hg porosimetry and BET surface measurements for conventional and spherical nickel hydroxides are summarized. Pore distribution and electrochemical activity for the nanophase materials will be examined in the future.

Reisner, David E.; Salkind, Alvin J.; Strutt, Peter R.; Xiao, T. Danny

130

Comparison of corrosivity of polymeric sulfate ferric and ferric chloride as coagulants in water treatment  

Microsoft Academic Search

This paper discusses the corrosion behavior of two coagulants used in water treatment, ferric chloride (FC) and polymeric ferric sulfate (PFS). Corrosion tests were performed to compare the corrosivity of these two coagulants on aluminum 6061 and steel 4140 specimens. Results showed that both temperature and concentration of the coagulants substantially impact corrosion rates. The corrosion rates increased with the

Yonghui Shi; Maohong Fan; Robert C Brown; Shihwu Sung

2004-01-01

131

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. PMID:16348395

Johnson, D. Barrie; McGinness, Stephen

1991-01-01

132

Magnetic properties and Mössbauer spectra of gamma ferric oxide and doped gamma ferric oxide  

Microsoft Academic Search

Magnetic hysteresis, Mössbauer spectra and temperature variation of initial magnetic susceptibility of thirteen samples of doped ?-Fe2O3 containing cobalt or gadolinium are determined. The samples containing more than 1.0% cobalt are found to have a multi-domain configuration, and undoped ?-Fe2O3, gadolinium-doped ?-Fe2O3 and doped ?-Fe2O3 containing less than 1.0% (except 0.3%) cobalt have a single domain configuration. Mössbauer spectra of

A. K. Nikumbh; Ganesh Khind

1990-01-01

133

The evaluation of HCl and Na-EDTA additions for ferric chloride testing using auger electron spectroscopy  

Microsoft Academic Search

Two different additions to the ASTM G48 ferric chloride solution: HCl and Na-EDTA, that prevent the precipitation of hydrous iron oxide at temperatures above 45 °C are discussed. Adding Na-EDTA gave surfaces with characteristics similar to those of the normal ferric chloride solution, whereas the HC1 addition caused an increase in passive layer thickness at higher temperatures. Critical pitting temperatures

C.-O. A. Olsson; P.-E. Arnvig

1995-01-01

134

High Strain Rate Response of Sandwich Composites with Nanophased Cores  

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

135

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

136

Kinetic and thermodynamic aspects of adsorption of arsenic onto granular ferric hydroxide (GFH)  

Microsoft Academic Search

Relatively limited information is available regarding the impacts of temperature on the adsorption kinetics and equilibrium capacities of granular ferric hydroxide (GFH) for arsenic (V) and arsenic (III) in an aqueous solution. In general, very little information is available on the kinetics and thermodynamic aspects of adsorption of arsenic compounds onto other iron oxide-based adsorbents as well. In order to

Kashi Banerjee; Gary L. Amy; Michele Prevost; Shokoufeh Nour; Martin Jekel; Paul M. Gallagher; Charles D. Blumenschein

2008-01-01

137

Removal of nickel and cadmium from battery waste by a chemical method using ferric sulphate.  

PubMed

The removal of nickel (Ni) and cadmium (Cd) from spent batteries was studied by the chemical method. A novel leaching system using ferric sulphate hydrate was introduced to dissolve heavy metals in batteries. Ni-Cd batteries are classified as hazardous waste because Ni and Cd are suspected carcinogens. More efficient technologies are required to recover metals from spent batteries to minimize capital outlay, environmental impact and to respond to increased demand. The results obtained demonstrate that optimal conditions, including pH, concentration of ferric sulphate, shaking speed and temperature for the metal removal, were 2.5, 60 g/L, 150 rpm and 30 degrees C, respectively. More than 88 (+/- 0.9) and 84 (+/- 2.8)% of nickel and cadmium were recovered, respectively. These results suggest that ferric ion oxidized Ni and Cd present in battery waste. This novel process provides a possibility for recycling waste Ni-Cd batteries in a large industrial scale. PMID:24701923

Jadhav, Umesh U; Hocheng, Hong

2014-01-01

138

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

139

Ferric chloride plus GAC for removing TOC  

Microsoft Academic Search

Granular activated carbon (GAC) treatment is one method that water utilities can use to increase removal of natural organic matter and comply with tibe recently promulgated Disinfectants\\/Disinfection By-products Rule. The cost of GAC depends on its useful service life and its capacity for reuse. The research reported here used minicolumns to investigate how ferric chloride coagulation influenced the total organic

Kirk O. Nowack; Fred S. Cannon; Harish Arora

1999-01-01

140

Modeling ferrous ferric iron chemistry with application to martian surface geochemistry  

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

141

Statistics of sub-Poissonian nucleation in a nanophase  

NASA Astrophysics Data System (ADS)

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

Glas, Frank

2014-09-01

142

Surface Enthalpies of Nanophase ZnO with Different Morphologies  

SciTech Connect

A direct calorimetric measurement of the dependence of the surface enthalpy of nanophase ZnO on morphology is reported. Nanoparticles, nanoporous composites, nanorods, and nanotetrapods were prepared with various sizes and their surface enthalpies were derived from their drop solution enthalpies in molten sodium molybdate. Water adsorption calorimetry for nanoparticles and nanorods was carried out to characterize the stabilization effect of surface hydration. The surface enthalpies of hydrated surfaces for nanoparticles, nanoporous composites, nanorods and nanotetrapods are 1.31±0.07, 1.42±0.21, 5.19±0.56, and 5.77±2.50 J/m2, respectively, while those of the anhydrous surfaces are 2.55±0.23, 2.74±0.16, 6.67±0.56, and 7.28±2.50 J/m2. The surface enthalpies of nanoparticles are the same as those of nanoporous composites, and are much lower than those of nanorods and nanotetrapods, which are also close to each other. The dependence of surface enthalpy on morphology is discussed in terms of exposed surface structures. This is the first time that calorimetry on nanocrystalline powders bas been able to detect differences in surface energetics of materials having different morphologies.

Zhang, Peng; Xu, Fen; Navrotsky, Alexandra; Lee, Jong Soo; Kim, Sangtae; Liu, Jun

2007-11-13

143

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

144

Intravenous ferric carboxymaltose for anaemia in pregnancy  

PubMed Central

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

2014-01-01

145

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

Microsoft Academic Search

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

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

146

46 CFR 151.50-75 - Ferric chloride solution.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 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,...

2011-10-01

147

46 CFR 151.50-75 - Ferric chloride solution.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 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,...

2010-10-01

148

Chromosome Damage Induced by Ferric Chloride in Human Peripheral Lymphocytes  

Microsoft Academic Search

The clastogenic activity of ferric chloride were observed on human lymphocyte culture in vitro after exposoure for 24 and 48 hrs. The results shows ferric chloride induces significantly high levels of chromosomal aberrations (%) and damaged cells (%) as compared to control. Period of exposure does not seem to affect the incidence to a significant level. Mitotic index however is

Sandeep Poddar; Geeta Talukder; Archana Sharma

2004-01-01

149

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

150

Mechanical and Optical Characterizations of Nanophase Diamond Films Prepared by a Laser Plasma Discharge Source.  

NASA Astrophysics Data System (ADS)

Films of nanophase diamond can be deposited at room temperature with a laser plasma discharge source of multiply charged carbon ions without the use of any catalyst in the growth mechanism. The beam from a Q-switched Nd:YAG laser is focused on graphite at intensities in excess of 10^{11} Wcm^ {-2} and the resulting plasma ejects carbon ions carrying energies of about 1 keV through a discharge space to the substrate to be coated. The nanophase diamond films that condense are composed of nanometer scale nodules of sp^3 bonded carbon. The high energy of condensation from the laser plasma source provides both the chemical bonding of such films to a wide variety of substrates and for low values of residual compressive stress. In this work, mechanical and optical characterizations of nanophase diamond films were extensively studied. An advanced nanoindentation technique utilizing the NanoTest device was used to measure the hardness of the films prepared by the UT-Dallas laser deposition system and other techniques. The raw data produced was analyzed with a conventional procedure and a hardness value of 125 GPa was obtained. To avoid model dependent interpretation, a differential loading pressure, independent of plastic depth, was used to give a lower limit on the hardness directly for the raw data. Comparable values of this lower limit, near 75 GPa was measured on crystalline diamond prepared by CVD and on nanophase diamond deposited by the laser plasma method. It was shown that the hardness of nanophase diamond films increased with laser intensities used to produce them. The nanoindentation technique was also used to assess the bonding strength of the films. Reproducible discontinuities in the variation of the penetration depth with load were obtained when adhesion failure occurred under indentations. Adhesion strength of films prepared from core and periphery of laser plasma were compared by means of nanoindentation and Rutherford backscattering techniques and impressive adhesion strength was found for films deposited from carbon ions passing through the core part of laser plasma. The optical properties at infrared (IR) wavelengths were studied with the aid of a Fourier transform infrared (FTIR) spectrometer. Transmission spectra of several free standing films on silicon frames were obtained. Using a simple model considering rough surface scattering and free carrier absorption, satisfactory fits to these transmission spectra were obtained and from them the optical properties of refractive index were extracted. The characterization studies performed in this research indicated a great potential for nanophase diamond films in optical and mechanical applications.

You, Jonghun

151

Sm3+ photoreduction in BaCl2 nanophases precipitated fluoroaluminate glasses under femtosecond laser irradiation.  

PubMed

Photoreduction of samarium-doped BaCl(2)-modified aluminofluoride glass by femtosecond laser irradiation and x-ray irradiation were investigated. Photoluminescence of samarium ions indicated that photoreduction of Sm(3+)?Sm(2+) efficiently occurred in glass samples containing more than 5 mol.% BaCl(2) after femtosecond laser irradiation, while dramatic change was not observed by x-ray irradiation. Transmission electron microscope results revealed that BaCl(2) nanophases only precipitated from glass matrix with a high BaCl(2) content by focusing femtosecond laser irradiation. Samarium ions were selectively incorporated into the precipitated nanophases, resulting in the enhancement of Sm(3+) photoreduction under lower laser power. PMID:21847170

Jiao, Qing; Song, Zhiguo; Yang, Zhengwen; Yu, Xue; Qiu, Jianbei

2011-08-15

152

Comparison of periodontal ligament cells responses to dense and nanophase hydroxyapatite.  

PubMed

Hydroxyapatite, a synthetic calcium phosphate ceramic, is used as a biomaterial for the restoration of human hard tissue as well as in techniques which aim to regenerate periodontal tissues. Generally, hydroxyapatite is believed to have osteoconductive effects and to be non-bioresorbable but not to induce to periodontal tissue regeneration. No report has been found on responses of periodontal ligament cells (PDLC), the main contributor to periodontal tissue regeneration, to nanoparticles of hydroxyapatite. The objective of this study was to investigate the possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Using a sol-gel method, the nanophase hydroxyapatite powders were fabricated. These powders were proved to comprise nanoparticles by transmission electron microscope examination. The primary periodontal ligament cells were cultured on dense particle hydroxyapatite and nanometer particle hydroxyapatite. The effects on proliferation of periodontal ligament cells on dense and nanoparticle hydroxyapatite were examined in vitro using a methyl thiazolil tetracolium (MTT) test. The intercellular effects were studied with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). In addition, the influence of the two materials on osteogenic differentiation was determined through measurement of alkaline phosphatase activity and flow cytometry. About 2, 3, and 4 days after treatment with nanoparticles of hydroxyapatite, the proliferation activity of the PDLC increased significantly compared with those proliferating on dense hydroxyapatite and of control PDLC, but no significant difference was found between the PDLC proliferation on dense hydroxyapatite and the control PDLCs. After 3 and 5 days' incubation with nanoparticles of hydroxyapatite, alkaline phosphatase activity was significantly increased as compared to PDLCs incubated with dense hydroxyapatite and control PDLCs. Intracellular engulfment was found in the cultured cells with nanophase hydroxyapatite under electron microscopy. The results suggest that nanophase hydroxyapatite can promote proliferation and osteogenic differentiation of periodontal ligament cells and further that it may be used as a bioresorbable agent in osseous restoration. PMID:17143736

Sun, Weibin; Chu, Chenlin; Wang, Juan; Zhao, Huating

2007-05-01

153

Self-assembled NAnophase Particle (SNAP) surface treatments for corrosion protection of AA2024-T3  

Microsoft Academic Search

The Self-assembled NAnophase Particle (SNAP) process is a method of forming functionalized silica nanoparticles in situ in an aqueous-based sol–gel process, and then crosslinking the nanoparticles to form a thin film. Using the SNAP approach, coating components and materials can be designed and built up from the molecular level, in a sort of “bottom-up” design process. The SNAP surface treatment

M. S. Donley; V. N. Balbyshev; N. N. Voevodin

2005-01-01

154

Mechanical and Optical Characterizations of Nanophase Diamond Films Prepared by a Laser Plasma Discharge Source  

Microsoft Academic Search

Films of nanophase diamond can be deposited at room temperature with a laser plasma discharge source of multiply charged carbon ions without the use of any catalyst in the growth mechanism. The beam from a Q-switched Nd:YAG laser is focused on graphite at intensities in excess of 10^{11} Wcm^ {-2} and the resulting plasma ejects carbon ions carrying energies of

Jonghun You

1994-01-01

155

Thermochemical Investigations of Nano-phase Ammonia Borane: Effect of Higher Loading  

NASA Astrophysics Data System (ADS)

Chemical hydrogen storage materials that release H2 by thermolysis without generating CO2 offer an attractive option. The ammonia borane is an attractive compound containing more than 18 wt% hydrogen. However, the kinetics of hydrogen release in not favorable in bulk materials where H2 is released at 114 ^oC. We recently reported use of SBA-15 as scaffold material to form a nanophase ammonia borane species which liberated H2 at significantly lower temperatures. Hydrogen formation from bulk AB is slightly exothermic (-5 kcal/mol). The reaction enthalpy (?H) for release of H2 from AB adsorbed into SBA-15 (1:1 w/w) was determined to be nearly thermoneutral---dramatically lower than the bulk material. A near thermoneutral reaction suggests that there would be less restrictive heat management issues, greater thermal stability and potentially a lower energy input requirement for regeneration of AB. One drawback which results for nano-phase AB is that while the hydrogen release properties are enhanced, the gravimetric hydrogen density is reduced by a 50% for the 1 to 1 by mass ratio material. We here report on our efforts to increase the gravimetric hydrogen density of nano-phase AB by developing higher loading conditions of AB adsorbed into mesoporous silica (MCM-41).

Karkamkar, Abhi; Stowe, Ashley; Autrey, Tom

2009-03-01

156

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

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

2003-01-01

157

ArsH from Synechocystis sp. PCC 6803 reduces chromate and ferric iron.  

PubMed

ArsH is widely distributed in bacteria, and its function remains to be characterized. In this study, we investigated the function of ArsH from Synechocystis sp. PCC 6803. The inactivation of arsH by insertion of a kanamycin-resistance gene in Synechocystis sp. PCC 6803 resulted in the decrease of arsenic and chromium accumulation compared with the wild type. ArsH expression in Escherichia coli strain Rosetta increased its resistance to chromate by reducing chromate in the medium and cells to chromium (III). In addition, ArsH in Rosetta conferred resistance to arsenic. The purified Synechocystis ArsH was able to reduce chromate and ferric iron at the expense of NADPH. Nonlinear regression values of K0.5 for chromate and ferric iron were 71.9 ± 17.8 ?M and 59.3 ± 13.8 ?M, respectively. The expression level of arsH was induced by arsenite and arsenate, but not chromate or ferric iron. Our results suggest that Synechocystis ArsH had no substrate specificities and shared some biochemical properties that other enzymes possessed. ArsH may be involved in coordinating oxidative stress response generated by arsenic. PMID:24861149

Xue, Xi-Mei; Yan, Yu; Xu, Hui-Juan; Wang, Ning; Zhang, Xiao; Ye, Jun

2014-07-01

158

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. PMID:9826636

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

1998-01-01

159

21 CFR 184.1296 - Ferric ammonium citrate.  

Code of Federal Regulations, 2010 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...

2010-04-01

160

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

161

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

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

2014-04-01

162

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

163

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

164

21 CFR 73.2298 - Ferric ammonium ferrocyanide.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

165

Organic functionalisation of graphene catalysed by ferric perchlorate.  

PubMed

We have developed a method to prepare covalently functionalised graphene using ferric perchlorate as the catalyst. The resulting functionalised graphene was characterised by Raman spectroscopy, TGA, XPS, AFM, and dispersibility tests in organic or aqueous media. PMID:25364793

Yang, Lei; He, Junpo

2014-11-18

166

Imaging and Nanoscale Characterization Group Center for Nanophase Materials Sciences  

E-print Network

Letters, Physical Review B, Applied Physics Letter, Journal of Applied Physics, Journal of Physics, Oxide Surfaces, Interfaces and Thin Films, DCMP. Referee to journals: Nature Physics, Physical Review of Sciences, University of Science and Technology of China Solid State Physics M.S., 1991 Peking University

Pennycook, Steve

167

Significant enhancement of Sm3+ photoreduction in halide nanophase precipitated AIF3-based glasses under femtosecond laser irradiation.  

PubMed

The electronegativity effect for the efficient photoreduction of Sm3+ to Sm2+ in Br-modified fluoroaluminate glasses was investigated after femtosecond laser (fs) irradiation. Sm2+ luminescence was strongly observed in the higher Br-modified samples, and basing on the TEM and DSC measurements, BaBr2 nanophases were precipitated from the glass matrix in the laser focused areas. From the EDS spectra, it was found that Sm3+ can be selectively incorporated into the BaBr2 nanophases. More electrons provided by the nanophase facilitated the Sm3+ reduction in the irradiation process. Since the photoreduction efficiency of Sm3+ in Br-modified glass is evidently higher than that in Cl-modified glasses, the effect of halide ions electronegativity on Sm3+ photoreduction was identified and relevant mechanism was discussed. PMID:23862455

Jiao, Qing; Yu, Xue; Yang, Zhengwen; Zhou, Dacheng; Qiu, Jianbei

2013-06-01

168

Ferric sulfates on Mars: Surface Explorations and Laboratory Experiments  

NASA Astrophysics Data System (ADS)

Recent results from missions to Mars have reinforced the importance of sulfates for Mars science. They are the hosts of water, the sinks of acidity, and maybe the most active species in the past and current surface/near-surface processes on Mars. Fe-sulfate was found frequently by Spirit and Opportunity rovers: jarosite in Meridiani Planum outcrops and a less specific "ferric sulfate" in the salty soils excavated by Spirit at Gusev Crater. Pancam spectral analysis suggests a variety of ferric sulfates in these soils, i.e. ferricopiapite, jarosite, fibroferrite, and rhomboclase. A change in the Pancam spectral features occurred in Tyrone soils after ~ 190 sols of exposure to surface conditions. Dehydration of ferric sulfate is a possible cause. We synthesized eight ferric sulfates and conducted a series of hydration/dehydration experiments. Our goal was to establish the stability fields and phase transition pathways of these ferric sulfates. In our experiments, water activity, temperature, and starting structure are the variables. No redox state change was observed. Acidic, neutral, and basic salts were used. Ferric sulfate sample containers were placed into relative humidity buffer solutions that maintain static relative humidity levels at three temperatures. The five starting phases were ferricopiapite (Fe4.67(SO4)6(OH)2.20H2O), kornelite (Fe2(SO4)3.7H2O), rhomboclase (FeH(SO4)2.4H2O), pentahydrite (Fe2(SO4)3.5H2O), and an amorphous phase (Fe2(SO4)3.5H2O). A total of one hundred fifty experiments have been running for nearly ten months. Thousands of coupled Raman and gravimetric measurements were made at intermediate steps to monitor the phase transitions. The first order discovery from these experiments is the extremely large stability field of ferricopiapite. Ferricopiapite is the major ferric sulfate to precipitate from a Fe3+-S-rich aqueous solution at mid-low temperature, and it has the highest H2O/Fe ratio (~ 4.3). However, unlike the Mg-sulfate with highest hydration state (epsomite, at mid-low temperature), which would dehydrate readily at low relative humidity, ferricopiapite remains unchanged over ten months under extremely dry conditions. On the other hand, amorphous ferric sulfate which forms easily from solutions at dry conditions, is similar to the amorphous magnesium sulfate in stability field, thus can potentially be a very important phase in the phase transition pathways of ferric sulfates on Mars.

Wang, A.; Ling, Z.; Freeman, J. J.

2008-12-01

169

Remediation of sulfidic wastewater by catalytic oxidation with hydrogen peroxide.  

PubMed

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

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

2009-01-01

170

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

171

Structure, Vol. 9, 311319, April, 2001, 2001 Elsevier Science Ltd. All rights reserved. PII S0969-2126(01)00589-5 Crystal Structures of a Novel Ferric Reductase  

E-print Network

, is not well understood. Respiration with Fe(III) is considered to be one of theUniversity of California, Los the ability to respire with oxygen [2]. Due to the possible photochemical oxidation of Fe(II) in the Archaean-eukaryotic assimilatory type of ferric reductases. How- ever, the high cellular abundance of the A. fulgidus FeR fate

Schroeder, Imke

172

The near-infra-red spectra of ferric acetylacetonate  

E-print Network

THE NEAR-INFRA-RED SPECTRA OF FERRIC ACEPILACE1ONATE A Thesis James Travis Owen Submitted to the Graduate College of the Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1965 Major... Subject: Chemistry THE lKAR-INFRA-RED SPECTRA GF FERRIC ACEIYLACE10NATE A Thesis By James Travis Owen Approved as to style and content by: Chairman of Committee . ad of Depart Nember ber iamb er August 1965 ACKNOWLEDGMENTS I wish to express...

Owen, James Travis

2012-06-07

173

Intravenous ferric carboxymaltose accelerates erythropoietic recovery from experimental malarial anemia.  

PubMed

Iron restriction has been proposed as a cause of erythropoietic suppression in malarial anemia; however, the role of iron in malaria remains controversial, because it may increase parasitemia. To investigate the role of iron-restricted erythropoiesis, A/J mice were infected with Plasmodium chabaudi AS, treated with intravenous ferric carboxymaltose at different times, and compared with untreated controls. Iron treatment significantly increased weight and hemoglobin nadirs and provided enhanced reticulocytosis and faster recovery, compared with controls. Our findings challenge the restrictive use of iron therapy in malaria and show the need for trials of intravenous ferric carboxymaltose as an adjunctive treatment for severe malarial anemia. PMID:22357662

Maretty, Lasse; Sharp, Rebecca Emilie; Andersson, Mikael; Kurtzhals, Jųrgen A L

2012-04-01

174

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

175

Heavy metal phosphate nanophases in silica: influence of radiolysis probed via f-electron state properties  

NASA Astrophysics Data System (ADS)

We have assessed the feasibility of carrying out time- and wavelength-resolved laser-induced fluorescence measurements of radiation damage in glassy silica. The consequences of alpha decay of Es-253 in LaPO 4 nanophases embedded in silica were probed based on excitation of 5 f states of Cm 3+, Bk 3+, and Es 3+ ions. The recorded emission spectra and luminescence decays showed that alpha decay of Es-253 ejected Bk-249 decay daughter ions into the surrounding silica and created radiation damage within the LaPO 4 nanophases. This conclusion is consistent with predictions of an ion transport code commonly used to model ion implantation. Luminescence from the 6D7/2 state of Cm 3+was used as an internal standard. Ion-ion energy transfer dominated the dynamics of the observed emitting 5 f states and strongly influenced the intensity of observed spectra. In appropriate sample materials, laser-induced fluorescence provides a powerful method for fundamental investigation of alpha-induced radiation damage in silica.

Beitz, James V.; Williams, C. W.; Hong, K.-S.; Liu, G. K.

2005-02-01

176

Soybean dihydrolipoamide dehydrogenase (ferric leghemoglobin reductase 2) interacts with and reduces ferric rice non-symbiotic hemoglobin 1§  

PubMed Central

Ferrous oxygenated hemoglobins (Hb2+O2) autoxidize to ferric Hb3+, but Hb3+ is reduced to Hb2+ by enzymatic and non-enzymatic mechanisms. We characterized the interaction between the soybean ferric leghemoglobin reductase 2 (FLbR2) and ferric rice non-symbiotic Hb1 (Hb13+). Spectroscopic analysis showed that FLbR2 reduces Hb13+. Analysis by tryptophan fluorescence quenching showed that FLbR2 interacts with Hb13+, however the use of ITC and IEF techniques revealed that this interaction is weak. In silico modeling showed that predicted FLbR2 and native Hb13+ interact at the FAD-binding domain of FLbR2 and the CD-loop and helix F of Hb13+.

Gopalasubramaniam, Sabarinathan K.; Kondapalli, Kalyan C.; Millįn-Pacheco, César; Pastor, Nina; Stemmler, Timothy L.; Moran, Jose F.; Arredondo-Peter, Raśl

2014-01-01

177

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

178

Spectrophotometric Ferric Ion Biosensor From Pseudomonas fluorescens Culture  

E-print Network

cultures produce fluorescent siderophores. By utilizing optimal conditions for maximizing siderophore min or smaller) for citrate as the accompanying anion with ferric ions. While the response time straightforward spectrophotometric appli- cations. We also show the utility of the biosensor with the high

Mittal, Aditya

179

Pretreatment of the Metropolitan Toronto Water Supply Utilizing Ferric Chloride  

Microsoft Academic Search

The treatment of high pH raw water with alum has produced problems with postprecipitation of aluminum complexes which clog mains. So a series of jar tests was initiated with ferric chloride to determine the effectiveness of flocculation and the quality of filtered water produced. Successful results led to testing on a plant scale at the smallest of Toronto's treatment facilities.

John A. Carnduff

1976-01-01

180

CORROSION OF ZIRCONIUM IN CUPRIC AND FERRIC CHLORIDES  

Microsoft Academic Search

The effect of metallurgical and surface treatments on the corrosion ; behavior of arc-melted reactor-grade zirconium in cupric or ferric chloride ; solutions was investigated. An apparatus was constructed and specimens of ; various metallurgical conditions and surface treatments were tested for 6 days at ; 35 deg C, with aeration. Some correlations were observed between corrosion rate ; and

D. J. Stoops; M. D. Carver; H. Kato

1961-01-01

181

Comparing polyaluminum chloride and ferric chloride for antimony removal  

Microsoft Academic Search

Antimony has been one of the contaminants required to be regulated, however, only limited information has been collected to date regarding antimony removal by polyaluminium chloride (PACl) and ferric chloride (FC). Accordingly, the possible use of coagulation by PACl or FC for antimony removal was investigated. Jar tests were used to determine the effects of solution pH, coagulant dosage, and

Meea Kang; Tasuku Kamei; Yasumoto Magara

2003-01-01

182

Effect of ferric chloride on fouling in membrane bioreactor  

Microsoft Academic Search

Membrane fouling has been the main obstacle to the wide application of membrane bioreactors (MBRs). The aim of this study was to investigate the effects of ferric chloride on retarding membrane fouling in MBRs. Changes in the modified fouling index (MFI) and the zeta potential of sludge flocs were used to determine the optimal concentration of Fe(III). The optimal Fe(III)

Hai-feng Zhang; Bao-sheng Sun; Xin-hua Zhao; Zheng-hong Gao

2008-01-01

183

Optimization of ferric hydroxide coprecipitation process for selenium removal from petroleum refinery stripped four water  

SciTech Connect

Iron coprecipitation was used in bench-scale tests to remove selenium from stripped sour water generated by two petroleum refineries. Chlorine dioxide and hydrogen peroxide were found to convert selenocyanate in the stripped sour water to selenite, which can be removed by iron coprecipitation. An iodometric titration procedure was developed to determine the required oxidant dose. Iron coprecipitation reduced selenium concentrations by 40 to 99 percent in stripped sour water after chlorine dioxide pretreatment Removal was less effective with hydrogen peroxide as the oxidant: total selenium concentrations were reduced by 28 to 92 percent in stripped sour water after hydrogen peroxide pretreatment. Highest removals were obtained at the highest oxidant and iron doses. Sludges produced in coprecipitation tests were hazardous under California regulations. Ozone oxidized selenocyanate but prevented ferric hydroxide precipitation or coagulation. Air was ineffective at selenocyanate oxidation. Repeatedly contacting iron hydroxide with stripped sour water pretreated with hydrogen peroxide, in a simulation of a countercurrent adsorption process, increased the selenium adsorbed on the solids from 32 to 147 pg selenium per mg of iron, but some of the adsorbed selenite was oxidized to selenate and desorbed back into solution.

Gerhardt, M.B.; Marrs, D.R.; Roehl, R.

1996-12-31

184

Kinetics of the ferrous/ferric electrode reaction in the absence of chloride catalysis  

SciTech Connect

The kinetics of the ferrous ferric redox electrode reaction has been investigated by many workers as a simple, uncomplicated charge transfer reaction which seems ideal for testing experimental techniques and charge transfer theories. However, it has only recently been understood that very small traces of chloride can have a considerable effect on the reaction rate. The relation between the chloride content of the solution and the rate constant of the ferrous/ferric reaction on a gold electrode in perchloric acid solutions is confirmed in this work. The chloride effect free apparent standard rate constant is found to be 2.2 x 10/sup -5/ cm s/sup -1/, which is two to three orders of magnitude smaller than the rate constants normally reported for this reaction if the chloride content of the solution is not scrupulously controlled. Measurements were carried out by using two different in situ methods for cleaning the working electrode surface rather than employing extensive solution purification. In the first method the measuring electrode was potentiostated at sufficiently negative potentials to desorb the chloride from the surface followed by a potential step to the equilibrium potential and a pulse measurement of the kinetics. In the second method chloride ions were removed from the surface before and during the kinetic measurement by continuous oxidation of chromous ions added in small concentration to the test solution. Good agreement was found among the rate constants determined by these methods and a reported rate constant determined in ultraclean solution.

Hung, N.C.; Nagy, Z.

1987-09-01

185

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

186

Ultraviolet and white photon avalanche upconversion in Ho3+-doped nanophase glass ceramics  

NASA Astrophysics Data System (ADS)

Ho3+-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 750nm. 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 20mW. 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.; Martķn, I. R.; Calvilla-Quintero, J. M.

2005-01-01

187

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

188

The facile and low temperature synthesis of nanophase hydroxyapatite crystals using wet chemistry.  

PubMed

A simple and facile wet chemistry route was used to synthesize nanophase hydroxyapatite (HaP) crystals at low temperature. The synthesis was carried out at a pH of 11.0 and at a temperature of 37°C. The resulting samples were washed several times and subjected to further analysis. XRD studies revealed that the HaP crystals were polycrystalline in nature with a crystallite size of ~15-60 ± 5 nm. SEM-EDXA images confirmed the presence of calcium (Ca), phosphorous (P), and oxygen (O) peaks. Likewise, FTIR confirmed the presence of characteristic phosphate and hydroxyl peaks in samples. Lastly, HRTEM images clearly showed distinctive lattice fringes positioned in the 100 and 002 planes. TGA analysis shows that HaP crystals can withstand higher calcination temperatures and are thermally stable. PMID:24433898

Dhand, Vivek; Rhee, K Y; Park, Soo-Jin

2014-03-01

189

Mechanism of Bacterial Pyrite Oxidation  

PubMed Central

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

Silverman, Melvin P.

1967-01-01

190

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. PMID:24900285

2011-01-01

191

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

192

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

193

Selective separation of ferric and non-ferric forms of human transferrin by capillary micellar electrokinetic chromatography.  

PubMed

The previously published method allowing the separation of non-ferric (iron-free) and ferric (iron-saturated) forms of human serum transferrin via capillary electrophoresis has been further developed. Using a surface response methodology and a three-factorial Doehlert design we have established a new optimized running buffer composition: 50mM Tris-HCl, pH 8.5, 22.5% (v/v) methanol, 17.5mM SDS. As a result, two previously unobserved monoferric forms of protein have been separated and identified, moreover, the loss of ferric ions from transferrin during electrophoretic separation has been considerably reduced by methanol, and the method selectivity has been yet increased resulting in a total separation of proteins exerting only subtle or none difference in mass-to-charge ratio. The new method has allowed us to monitor the gradual iron saturation of transferrin by mixing the iron-free form of protein with the buffers with different concentrations of ferric ions. It revealed continuously changing contribution of monoferric forms, characterized by different affinities of two existing iron binding sites on N- and C-lobes of protein, respectively. Afterwards, the similar experiment has been conducted on-line, i.e. inside the capillary, comparing the effectiveness of two possible modes of the reactant zones mixing: diffusion mediated and electrophoretically mediated ones. Finally, the total time of separation has been decreased down to 4min, taking the advantage from a short-end injection strategy and maintaining excellent selectivity. PMID:24690308

Nowak, Pawe?; ?piewak, Klaudyna; Nowak, Julia; Brindell, Ma?gorzata; Wo?niakiewicz, Micha?; Stochel, Gra?yna; Ko?cielniak, Pawe?

2014-05-01

194

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

NASA Technical Reports Server (NTRS)

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

Burns, Roger G.; Fisher, Duncan S.

1991-01-01

195

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

196

C-H bond activation by a ferric methoxide complex: modeling the rate-determining step in the mechanism of lipoxygenase.  

PubMed

Lipoxygenases are mononuclear non-heme iron enzymes that regio- and stereospecifcally convert 1,4-pentadiene subunit-containing fatty acids into alkyl peroxides. The rate-determining step is generally accepted to be hydrogen atom abstraction from the pentadiene subunit of the substrate by an active ferric hydroxide species to give a ferrous water species and an organic radical. Reported here are the synthesis and characterization of a ferric model complex, [Fe(III)(PY5)(OMe)](OTf)(2), that reacts with organic substrates in a manner similar to the proposed enzymatic mechanism. The ligand PY5 (2,6-bis(bis(2-pyridyl)methoxymethane)pyridine) was developed to simulate the histidine-dominated coordination sphere of mammalian lipoxygenases. The overall monoanionic coordination provided by the endogenous ligands of lipoxygenase confers a strong Lewis acidic character to the active ferric site with an accordingly positive reduction potential. Incorporation of ferrous iron into PY5 and subsequent oxidation yields a stable ferric methoxide species that structurally and chemically resembles the proposed enzymatic ferric hydroxide species. Reactivity with a number of hydrocarbons possessing weak C-H bonds, including a derivative of the enzymatic substrate linoleic acid, scales best with the substrates' bond dissociation energies, rather than pK(a)'s, suggesting a hydrogen atom abstraction mechanism. Thermodynamic analysis of [Fe(III)(PY5)(OMe)](OTf)(2) and the ferrous end-product [Fe(II)(PY5)(MeOH)](OTf)(2) estimates the strength of the O-H bond in the metal bound methanol in the latter to be 83.5 +/- 2.0 kcal mol(-1). The attenuation of this bond relative to free methanol is largely due to the high reduction potential of the ferric site, suggesting that the analogously high reduction potential of the ferric site in LO is what allows the enzyme to perform its unique oxidation chemistry. Comparison of [Fe(III)(PY5)(OMe)](OTf)(2) to other coordination complexes capable of hydrogen atom abstraction shows that, although a strong correlation exists between the thermodynamic driving force of reaction and the rate of reaction, other factors appear to further modulate the reactivity. PMID:11772065

Goldsmith, Christian R; Jonas, Robert T; Stack, T Daniel P

2002-01-01

197

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

SciTech Connect

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

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

2003-09-15

198

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. PMID:24876963

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

2014-01-01

199

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

200

Corynebactin and a Serine Trilactone Based Analogue-Chirality and Molecular Modeling of ferric Complexes  

SciTech Connect

The chirality of ferric siderophore complexes is a determinant for their cellular recognition and transport. Corynebactin (first isolated from a Gram-positive bacterium) contains L-threonine, unlike the closely related enterobactin, which contains L-serine. Also unlike enterobactin, ferric corynebactin is preferentially L at the iron center. Experimental (circular dichroism spectra and synthesis of a corynebactin/enterobactin hybrid) and theoretical (MM3 and density functional theory calculations) results explain ferric corynebactin's properties.

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

2002-09-14

201

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

Microsoft Academic Search

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

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

2011-01-01

202

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

Microsoft Academic Search

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

Ulusoy Bali; Bünyamin Karagözo?lu

2007-01-01

203

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

Microsoft Academic Search

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

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

2010-01-01

204

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. PMID:23221350

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

2013-01-01

205

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

206

Particulate and THM precursor removal with ferric chloride  

SciTech Connect

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

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

1999-11-01

207

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

208

Deposition rates of oxidized iron on Mars  

NASA Technical Reports Server (NTRS)

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

Burns, R. G.

1993-01-01

209

Organic matter mineralization with reduction of ferric iron in anaerobic sediments  

Microsoft Academic Search

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

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

1986-01-01

210

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

Microsoft Academic Search

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

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

1996-01-01

211

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

212

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

213

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

214

The stability of oxyamphiboles: Existence of Ferric-bearing minerals under the reducing conditions on the surface of Venus  

NASA Technical Reports Server (NTRS)

An enigma of Venusian mineralogy is the suggestion that Fe(3+)-bearing minerals exist under the reducing conditions of the Venusian atmosphere. Analysis of the spectrophotometric data from the Venera 13 and 14 missions, combined with the laboratory reflectance spectral measurements of oxidized basalts at elevated temperatures, led to the suggestion that metastable hematite might exist on Venus. Heating experiments at 475 C when f(sub O2) approximately 10(exp -24) demonstrated that the hematite to magnetite conversion is rapid indicating metastable hematite is not present on Venus. In addition to hematite, several other ferric oxide and silicate minerals have been proposed to occur on Venus, including laihunite or ferrifayalite, Fe(3+)-bearing tephroite, oxyamphiboles, and oxybiotites. Heating experiments performed on these Fe(3+)-bearing minerals under temperature-f(sub O2) conditions existing on Venus suggest that only oxyamphiboles and oxybiotites may be stable on the surface of Venus.

Straub, Darcy W.; Burns, Roger G.

1993-01-01

215

Fe{sup II} induced mineralogical transformations of ferric oxyhydroxides into magnetite of variable stoichiometry and morphology  

SciTech Connect

The Moessbauer spectroscopy was used to monitor the mineralogical transformations of ferrihydrite (F), lepidocrocite (L) and goethite (G) into magnetite as a function of aging time. Ferric oxyhydroxides were reacted with soluble Fe{sup II} and OH{sup -} in stoichiometric amounts to form magnetite at an initial pH of {approx}9.7. Observed transformation extent into magnetite followed the order: F>L>G with almost 30% of untransformed G after 1 month. The departure from stoichiometry, {delta}, of magnetite (Fe{sub 3-{delta}}O{sub 4}) generated from F ({delta}{approx}0.04) and L ({delta}{approx}0.05) was relatively low as compared to that in magnetite from G ({delta}{approx}0.08). The analysis by transmission electron microscopy and BET revealed that generated magnetite was also different in terms of morphology, particle size and surface area depending on the nature of initial ferric oxyhydroxide. This method of preparation is a possible way to form nano-sized magnetite. - Graphical abstract: Moessbauer spectrum of the early stage of magnetite formation formed from the interaction of adsorbed Fe{sup II} species with goethite. Highlights: Black-Right-Pointing-Pointer Ferric oxides were reacted with hydroxylated Fe{sup II} to form magnetite. Black-Right-Pointing-Pointer Magnetite formation was quantified as a function of aging time. Black-Right-Pointing-Pointer Complete transformation of ferrihydrite and lepidocrocite was achieved. Black-Right-Pointing-Pointer Almost 70% of initial goethite was transformed. Black-Right-Pointing-Pointer Resulting magnetites have differences in stoichiometry and morphological properties.

Usman, M. [Universite de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France) [Universite de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France); CNRS, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France); Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38040 (Pakistan); Abdelmoula, M. [Universite de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France) [Universite de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France); CNRS, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France); Hanna, K. [Universite de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France) [Universite de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France); CNRS, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Institut Jean Barriol, CNRS-, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France); Ecole Nationale Superieure de Chimie de Rennes, UMR CNRS 6226 'Sciences Chimiques de Rennes', Avenue du General Leclerc, 35708 Rennes Cedex 7 (France); and others

2012-10-15

216

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

PubMed

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

Troxell, Bryan; Hassan, Hosni M

2013-01-01

217

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

EPA Science Inventory

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

218

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

PubMed

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

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

2008-02-21

219

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. PMID:24671940

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

220

Processes for extraction of uranium and radium from uranium-containing ores using ferric nitrate  

SciTech Connect

A process is described for the extraction of both uranium and radium from uranium ores in the presence of an interfering sulfate ion resulting from the presence of sulfide therein by use of an aqueous ferric nitrate leachant including the steps of: (a) mechanically treating the finely ground ore for the removal of sulfide therefrom; (b) leaching the mechanically treated finely ground ore with aqueous acidic ferric nitrate solution in a concentration from 0.01 to 0.1M for the removal of uranium and radium therefrom to result in a liquid ferric nitrate leachate containing radium and uranium and a wet cake containing radium, uranium and ferric nitrate; (c) treating the ferric nitrate leachate to separate uranium and radium therefrom; (d) separately treating the wet cake for removal of retained ferric nitrate and the residual radium and uranium therefrom; and (e) recirculating a major portion of the ferric nitrate leachate from step (c) for the leaching of more of the mechanically treated finely ground ore.

Nirdosh, I.

1987-03-10

221

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

222

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

223

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

PubMed

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 weight cytochrome (Hmc) complex, respectively, were able to reduce Fe(III) chelated with nitrilotriacetic acid (NTA), but not insoluble ferric oxide, with lactate as the electron donor. The rate and extent of Fe(III)-NTA reduction followed the order hyn = WT > hmc > hyd, suggesting that reduction of soluble Fe(III) is a periplasmic process that requires the presence of periplasmic [FeFe] hydrogenase. Reduction of Fe(III)-NTA was not coupled to cell growth. In fact cell concentrations declined when D. vulgaris was incubated with Fe(III)-NTA as the only electron acceptor. Wild type and mutant cells reducing a limiting concentration of sulfate (2 mM), reduced Fe(III)-NTA with similar rates. However, these were similarly incapable of catalyzing subsequent lactate-dependent reduction of Fe(III)-NTA to completion. Periplasmic reduction of Fe(III)-NTA appeared to inhibit the productive, sulfate-reducing metabolism of D. vulgaris, possibly because it prevents the cycling of reducing equivalents needed to achieve a net bioenergetic benefit. PMID:17588123

Park, Hyung Soo; Lin, Shiping; Voordouw, Gerrit

2008-01-01

224

NOM removal by adsorption onto granular ferric hydroxide: Equilibrium, kinetics, filter and regeneration studies.  

PubMed

Adsorption onto granular ferric hydroxide (GFH) with subsequent in-situ regeneration is studied as a new process for natural organic matter (NOM) removal from groundwater. Adsorbent equilibrium loadings of 10-30 mgDOC g(-1)GFH(-1) are obtained, whereas the non-adsorbable DOC fraction amounts to 1.5 mgL(-1) for all investigated groundwaters. The larger and UV-active NOM fractions (mainly fulvic acids) are well adsorbed while the smaller molecular fractions are poorly or not adsorbed. However, kinetic studies show that the smaller and medium-sized fulvic acids are removed first. The equilibrium is strongly dependent on pH but only weakly on ionic strength, pointing to ligand exchange as the dominant adsorption mechanism. With regard to NOM structure, prerequisites for adsorption onto GFH are both a minimum number of functional groups and a molecular size small enough to enter the GFH pores. NOM breakthrough curves are successfully simulated using the LDF model (homogeneous surface diffusion model (HSDM) with linear driving force approach for surface diffusion) and experimentally determined mass transfer coefficients. Regeneration of loaded GFH is possible either by use of NaOH or oxidatively by H(2)O(2). The optimal quantities and concentrations are determined. PMID:17681584

Genz, Arne; Baumgarten, Benno; Goernitz, Mandy; Jekel, Martin

2008-01-01

225

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 Grenčche; Emmanuelle Liger

2005-01-01

226

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

227

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

228

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

PubMed

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

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

2014-01-01

229

Bromate removal from water by granular ferric hydroxide (GFH).  

PubMed

The feasibility of granular ferric hydroxide (GFH) for bromate removal from water has been studied. Batch experiments were performed to study the influence of various experimental parameters such as effect of contact time, initial bromate concentration, temperature, pH and effect of competing anions on bromate removal by GFH. The adsorption kinetics indicates that uptake rate of bromate was rapid at the beginning and 75% adsorption was completed in 5 min and equilibrium was achieved within 20 min. The sorption process was well described by pseudo-second-order kinetics. The maximum adsorption potential of GFH for bromate removal was 16.5 mg g(-1) at 25 degrees C. The adsorption data fitted well to the Langmuir model. The increase in OH peak and absence of Br-O bonding in FTIR spectra indicate that ion-exchange was the main mechanism during bromate sorption on GFH. The effects of competing anions and solution pHs (3-9) were negligible. Results of the present study suggest that GFH can be effectively utilized for bromate removal from drinking water. PMID:19481866

Bhatnagar, Amit; Choi, Yanghun; Yoon, Yeojoon; Shin, Yongsoon; Jeon, Byong-Hun; Kang, Joon-Wun

2009-10-15

230

Localized corrosion of candidate container materials in ferric chloride solutions  

SciTech Connect

Localized corrosion behavior of candidate inner- and outer-container materials of current nuclear waste package design 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 516 carbon steel (UNS K01800), and high-performance UNS N08825, UNS N06985, UNS N06030, UNS N06455, UNS N06625, UNS N06022, and UNS R53400. A 516 steel suffered from severe general and localized attack including pitting and crevice corrosion. High-nickel UNS N08825 and N06985 also became susceptible to severe pitting and crevice corrosion. The extent of localized attack was less pronounced in UNS N06030 and N06455. UNS N06625 experienced severe surface degradation including general corrosion crevice corrosion and intergranular attack. In contrast, only slight crevice corrosion tendency was observed with nickel-base UNS N06022 in solutions containing higher concentrations of FeCl{sub 3} at 60 C and 90 C. UNS R53400 was immune to localized attack in all tested environments. The test solutions showed a significant amount of precipitated particles, especially at higher temperatures.

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

1999-07-01

231

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

232

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

PubMed Central

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

Santiago, Palacios

2012-01-01

233

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

234

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

235

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

Microsoft Academic Search

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

Yuan Wang; Pengyi Zhang; Gang Pan; Hao Chen

2008-01-01

236

The precipitation of hematite from ferric chloride media at atmospheric pressure  

Microsoft Academic Search

The precipitation of hematite from ferric chloride media at temperatures <100 C and at ambient pressure was studied as part\\u000a of a program to recover a marketable iron product from metallurgical processing streams or effluents. Hematite (Fe2O3) can be formed in preference to ferric oxyhydroxides (e.g., ?-FeOOH) at temperatures as low as 60 C by controlling the precipitation conditions, especially

J. E. Dutrizac; P. A. Riveros

1999-01-01

237

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

Microsoft Academic Search

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

Danna Zhou; Feng Wu; Nansheng Deng; Wu Xiang

2004-01-01

238

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

239

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

PubMed Central

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

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

2013-01-01

240

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

PubMed

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 microg L(-1)), coagulant dose (0.5-60 mg L(-1)) and pH (4-9) were investigated. Experimental data were used for determination of the response functions coefficients. Predicted values of arsenate removal obtained using the response functions were in good agreement with the experimental data. Fe(III) ions were more effective and economic than Fe(II) ion due to required lower coagulant dose and pH. In the low initial arsenate concentrations, the highest arsenate removal efficiency was required high ferric chloride and ferric sulfate dose of 50 and 40 mg L(-1), while in the high initial arsenate concentrations, the highest arsenate removal efficiency was provided at low ferric chloride and ferric sulfate dose of 37 and 32 mg L(-1), respectively. This study showed that Box-Behnken design and response surface methodology was reliable and effective in determining the optimum conditions for arsenic removal by coagulation and flocculation. PMID:19147281

Baskan, Meltem Bilici; Pala, Aysegul

2009-07-30

241

Existence of a new type of sulfite oxidase which utilizes ferric ions as an electron acceptor in Thiobacillus ferrooxidans.  

PubMed Central

A new type of sulfite oxidase which utilizes ferric ion (Fe3+) as an electron acceptor was found in iron-grown Thiobacillus ferrooxidans. It was localized in the plasma membrane of the bacterium and had a pH optimum at 6.0. Under aerobic conditions, 1 mol of sulfite was oxidized by the enzyme to produce 1 mol of sulfate. Under anaerobic conditions in the presence of Fe3+, sulfite was oxidized by the enzyme as rapidly as it was under aerobic conditions. In the presence of o-phenanthroline or a chelator for Fe2+, the production of Fe2+ was observed during sulfite oxidation by this enzyme under not only anaerobic conditions but also aerobic conditions. No Fe2+ production was observed in the absence of o-phenanthroline, suggesting that the Fe2+ produced was rapidly reoxidized by molecular oxygen. Neither cytochrome c nor ferricyanide, both of which are electron acceptors for other sulfite oxidases, served as an electron acceptor for the sulfite oxidase of T. ferrooxidans. The enzyme was strongly inhibited by chelating agents for Fe3+. The physiological role of sulfite oxidase in sulfur oxidation of T. ferrooxidans is discussed. PMID:3345075

Sugio, T; Katagiri, T; Moriyama, M; Zhen, Y L; Inagaki, K; Tano, T

1988-01-01

242

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

SciTech Connect

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

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

2007-08-22

243

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

PubMed

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

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

2014-08-27

244

Effects of pH and ferric ions on the antioxidant activity of olive polyphenols in oil-in-water emulsions  

Microsoft Academic Search

The effects of four phenolic compounds occurring in olives and virgin olive oil, namely, oleuropein, hydroxytyrosol, 3,4-dihydroxyphenylethanol-elenolic\\u000a acid (3,4-DHPEA-EA) and 3,4-dihydroxyphenylethanol-elenolic acid dialdehyde (3,4-DHPEA-EDA), on the oxidative stability of\\u000a stripped olive oil-in-water emulsions were studied at three pH values in the presence or absence of ferric chloride at 60°C.\\u000a In the stability test, the addition of phenolic compounds in emulsions

Fįtima Paiva-Martins; Michael H. Gordon

2002-01-01

245

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. PMID:23029129

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

2012-01-01

246

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

247

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

Microsoft Academic Search

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

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

2001-01-01

248

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

249

Treatment of Iron Deficiency With Intravenous Ferric Carboxymaltose in General Practice: A Retrospective Database Study  

PubMed Central

Background Iron deficiency is a frequent problem in general practice. Oral supplementation may in some cases not be well tolerated or not be efficient. Intravenous ferric carboxymaltose may be an alternative for iron supplementation in general practice. The aim of the present study was to analyze the indications for and the efficacy of intravenous ferric carboxymaltose in a primary care center. Methods We retropectively analyzed electronic data from 173 patients given intravenous ferric carboxymaltose between 2011 and 2013 in primary care center with 18 GPs in Bern, Switzerland. Results Of all patients, 34% were treated intravenously due to an inappropriate increase in ferritin levels after oral therapy, 24% had side effects from oral treatment, 10% were treated intravenously due to the patients explicit wish, and in 39% of all cases, no obvious reason of intravenous instead of oral treatment could be found. Intravenous ferric carboxymaltose led to a significant increase in hemoglobin and serum ferritin levels. Side effects of intravenous treatment were found in 2% of all cases. Conclusion We conclude that treatment with intravenous ferric carboxymaltose is an efficient alternative for patients with iron deficiency in general practice, when oral products are not well tolarated or effective. As treatment with iron carboxymaltose is more expensive and potentially dangerous due to side effects, the indication should be placed with (more) care. PMID:25368700

Kuster, Martina; Meli, Damian N.

2015-01-01

250

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

PubMed

The great enhancement of ferric ion on the photochemical decomposition of environmentally persistent perfluorooctanoic acid (PFOA) under 254nm UV light was reported. In the presence of 10microM ferric ion, 47.3% of initial PFOA (48microM) was decomposed and the defluorination ratio reached 15.4% within 4h reaction time. While the degradation and defluorination ratio greatly increased to 80.2% and 47.8%, respectively, when ferric ion concentration increased to 80microM, and the corresponding half-life was shortened to 103min. Though the decomposition rate was significantly lowered under nitrogen atmosphere, PFOA was efficiently decomposed too. Other metal ions like Cu(2+) and Zn(2+) also slightly improved the photochemical decomposition of PFOA under irradiation of 254nm UV light. Besides fluoride ion, other intermediates during PFOA decomposition including formic acid and five shorter-chain perfluorinated carboxylic acids (PFCAs) with C7, C6, C5, C4 and C3, respectively, were identified and quantified by IC or LC/MS. The mixture of PFOA and ferric ion had strong absorption around 280nm. It is proposed that PFOA coordinates with ferric ion to form a complex, and its excitation by 254nm UV light leads to the decomposition of PFOA in a stepwise way. PMID:18400382

Wang, Yuan; Zhang, Pengyi; Pan, Gang; Chen, Hao

2008-12-15

251

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. PMID:25006339

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

2014-01-01

252

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

253

Uptake mechanisms for inorganic iron and ferric citrate in Trichodesmium erythraeum IMS101.  

PubMed

Growth of the prevalent marine organism Trichodesmium can be limited by iron in natural and laboratory settings. This study investigated the iron uptake mechanisms that the model organism T. erythraeum IMS101 uses to acquire iron from inorganic iron and iron associated with the weak ligand complex, ferric citrate. IMS101 was observed to employ two different iron uptake mechanisms: superoxide-mediated reduction of inorganic iron in the surrounding milieu and a superoxide-independent uptake system for ferric citrate complexes. While the detailed pathway of ferric citrate utilization remains to be elucidated, transport of iron from this complex appears to involve reduction and/or exchange of the iron out of the complex prior to uptake, either at the outer membrane of the cell or within the periplasmic space. Various iron uptake strategies may allow Trichodesmium to effectively scavenge iron in oligotrophic ocean environments. PMID:25222699

Roe, Kelly L; Barbeau, Katherine A

2014-10-22

254

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. PMID:23472676

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

2013-01-01

255

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

PubMed

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

Steiner, M; Lazaroff, N

1974-11-01

256

Direct Method for Continuous Determination of Iron Oxidation by Autotrophic Bacteria  

PubMed Central

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

Steiner, Michael; Lazaroff, Norman

1974-01-01

257

Ferric sulfates on Mars: A combined mission data analysis of salty soils at Gusev crater and laboratory experimental investigations  

E-print Network

Ferric sulfates on Mars: A combined mission data analysis of salty soils at Gusev crater), Ferric sulfates on Mars: A combined mission data analysis of salty soils at Gusev crater and laboratory] Sulfate is one of the major types of secondary minerals found on Mars by recent missions, which reinforces

258

A Comparative Study of Iron Bioavailability from Cocoa Supplemented with Ferric Pyrophosphate or Ferrous Fumarate in Rats  

Microsoft Academic Search

Background: Food iron fortification can be a good strategy to prevent iron deficiency. Iron bioavailability from cocoa powder enriched with ferric pyrophosphate encapsulated in liposomes or ferrous fumarate was assessed in rats. Methods: Three groups of rats consumed during 28 days either a control diet or two diets prepared with ferric pyrophosphate- or ferrous fumarate-enriched cocoa powder as the unique

S. Navas-Carretero; B. Sarriį; A. M. Pérez-Granados; S. Schoppen; M. Izquierdo-Pulido; M. P. Vaquero

2007-01-01

259

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

260

Natural media with negative index of refraction: Perspectives of complex transition metal oxides (Review Article)  

NASA Astrophysics Data System (ADS)

The capabilities of perovskite-like compounds with the effect of colossal magnetoresistance (CMR) and some other complex oxides to have a negative index of refraction (NIR) are considered. Physical properties of these compounds are also analyzed from the standpoint of designing tunable metamaterials on their base. Of particular interest are temperature and magnetic field driven first-order transformations in oxides with perovskite structure and in spinels. These transformations give rise to nanophase separated states, using which the properties of negative refraction can be affected. The magnetic-field controlled metamaterials with CMR oxides as a boundary NIR media for a photonic crystal are discussed.

Fertman, E. L.; Beznosov, A. B.

2011-07-01

261

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. PMID:24976842

Nouri, Saeed; Sharif, Mohammad Reza

2014-01-01

262

Catalytic Friedel–Crafts Acylation of Alkoxy Benzenes by Ferric Hydrogensulfate  

Microsoft Academic Search

Friedel–Crafts acylation of alkoxy benzenes is achieved efficiently by reaction with aliphatic acid anhydrides in the presence of catalytic amounts of ferric hydrogensulfate, Fe(HSO4)3, in nitromethane. Alkyl benzenes and aryl halides, as well as aromatic anhydrides, remain intact under these conditions.

Peyman Salehi; Mohammad Mahdi Khodaei; Mohammad Ali Zolfigol; Shahpour Zeinoldini

2003-01-01

263

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

E-print Network

connects the aqueous solution to the heme site. Ferric horseradish peroxidase has an absorption band at 640, the protein was incorporated into trehalose/sucrose glasses and the hydration of the sugar glasses was varied are narrower for the protein in glycerol/water (glass transition at 150 K) than in trehalose/sucrose (glass

Sharp, Kim

264

Microdetermination of proteins by resonance light scattering technique based on aggregation of ferric nanoparticles.  

PubMed

A new method for protein determination is presented that allows measurement of proteins at nanogram levels with simple procedure. The method applies a resonance light scattering (RLS) technique, but based on aggregation of ferric nanoparticles on protein template instead of the usual interaction of organic days with proteins. By mixing ferric colloid with sodium cacodylate buffer solution, ferric nanoparticles can be obtained in the size of about 5nm and kept their positive charges in a wide range of pH 1.8-7.6. The ferric nanoparticles can interact with proteins to form particular aggregates and thus result in strong and stable RLS. Under optimal conditions (wavelength of 451nm and pH 7.4), few substances interfere with this assay. The detection limitation of bovine serum albumin (BSA) is 6.6ng/mL and the linear range is 20-700ng/mL. This method gives almost identical responses for BSA, human serum albumin (HSA) and gamma-globulin (gamma-G), and can be used for the determination of total proteins in human serum with satisfactory results. PMID:19111501

Shu-hong, Zhang; Yong-shan, Fan; Shuo, Feng; Yun-feng, Zhang

2009-05-01

265

Identification and Characterization of a Novel Ferric Reductase from the Hyperthermophilic Archaeon Archaeoglobus fulgidus*  

E-print Network

. The purified enzyme strictly requires FMN or FAD as a catalytic in- termediate for Fe3 reduction. Ferric reductase also re- duces FMN and FAD, but not riboflavin, with NAD(P)H which classifies the enzyme as a NAD enzyme. Acquisition of iron for assimilation into cellular protein is a universal trait of life. Iron

Schroeder, Imke

266

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

Microsoft Academic Search

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

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

2005-01-01

267

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

PubMed

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

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

2014-03-15

268

Coagulation removal of melanoidins from biologically treated molasses wastewater using ferric chloride  

Microsoft Academic Search

The pigments (melanoidins) in molasses wastewater are refractory to conventional biological treatment. Ferric chloride was used as coagulant to remove color and chemical oxygen demand (COD) from molasses effluent. Using jar test procedure, main operating conditions such as pH and coagulant dosage were investigated. Under the optimum conditions, up to 86% and 96% of COD and color removal efficiencies were

Zhen Liang; Yanxin Wang; Yu Zhou; Hui Liu

2009-01-01

269

A Study on Removing Basic Nitrogen Compounds From Diesel Oil by Ferric Chloride Complexing Agent  

Microsoft Academic Search

Removal of the basic nitrogen compounds from diesel oil by using ferric chloride as complexing agent was studied. The influence of affect factors on treating conditions was investigated, and orthogonal tests were done to conform the optimum process condition. The results showed that the optimum condition was that of the volume ratio of complexing agent to oil was 1.0, stirring

H. Yu; Z. Hu

2012-01-01

270

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

Microsoft Academic Search

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

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

1998-01-01

271

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

PubMed

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

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

2012-02-01

272

The use of ferric chloride and anionic polymer in the chemically assisted primary sedimentation process  

Microsoft Academic Search

Chemically Enhanced Primary Treatment (CEPT) or Chemically Assisted Primary Sedimentation Process (CAPS) involves the use of chemical coagulants to enhance the coagulation or flocculation of wastewater particles. The effect of a metal salt, ferric chloride (FeCl3) and an anionic polymer on the removal of suspended solids (SS) of wastewater collected from two sewage treatment plants was studied by jar test

C. S. Poon; C. W. Chu

1999-01-01

273

Ferric Reductase of Saccharomyces cerevisiae: Molecular Characterization, Role in Iron Uptake, and Transcriptional Control by Iron  

Microsoft Academic Search

The principal iron uptake system of Saccharomyces cerevisiae utilizes a reductase activity that acts on ferric iron chelates external to the cell. The FRE1 gene product is required for this activity. The deduced amino acid sequence of the FRE1 protein exhibits hydrophobic regions compatible with transmembrane domains and has significant similarity to the sequence of the plasma membrane cytochrome b558

Andrew Dancis; Dragos G. Roman; Gregory J. Anderson; Alan G. Hinnebusch; Richard D. Klausner

1992-01-01

274

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

275

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

276

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

277

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

278

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

279

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. PMID:24899820

Thomas, Anila; Peterson, Leif E

2014-01-01

280

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. PMID:12223760

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

1997-01-01

281

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

282

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

283

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

NASA Astrophysics Data System (ADS)

The knowledge of transport properties such as atomic diffusion, viscosity and electrical conductivity in the ferropericlase-magnesiowüstite solid solution, (Mg,Fe)O, is critical for understanding the dynamics of the lower mantle. Previous studies suggest that dominant positively-charged point defects in (Mg,Fe)O may change with pressure: ferric iron (Fe3+) dominates at low pressure while protons (H+) may dominate at high pressure. Consequently, the behavior of diffusion-related properties of (Mg,Fe)O likely changes with pressure from mechanisms sensitive to Fe3+ content (or oxygen fugacity) to those sensitive to H+ content (or water fugacity). However, the critical conditions above which water fugacity plays an important role are not well explored at present. In this study, we conducted high-pressure and high-temperature multianvil experiments on interdiffusion of Mg and Fe in (Mg,Fe)O at 5-15 GPa, 1673-1873 K with various oxygen fugacity buffers (Mo-MoO2, Ni-NiO, Re-ReO2) under nominally dry or water-saturated conditions. We also conducted experiments to constrain hydrogen solubility in MgO using various water fugacity buffers (periclase-brucite, periclase-clinohumite-forstelite). Our goals are a) to characterize the concentration of point defects to determine the conditions of solubility crossover between Fe3+ and H+ and b) to quantify the relative contributions of oxygen fugacity and water fugacity on Mg-Fe interdiffusivity. We measured the iron oxidation state of (Mg,Fe)O diffusion pairs by the flank method and Mössbauer spectroscopy, and hydrogen concentration by infrared spectroscopy. We found that Fe3+ concentration and Mg-Fe interdiffusivity are positively dependent on oxygen fugacity but not on water fugacity under the conditions we explored. Strong oxygen fugacity dependence is consistent with a diffusion model based on defect mechanisms since cation vacancies charge-balanced by Fe3+ are significantly more abundant than those charge-balanced by H+ under these conditions.

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

2010-12-01

284

Hydrous Ferric Oxide (HFO)—a Scavenger for Fluoride from Contaminated Water  

Microsoft Academic Search

Groundwaters contaminated with excess fluoride (above 1.5 mg\\/L) posed some risks to the public health in India. Methods available for fluoride contaminated water treatment are cogaulation–filtration using alum + lime + bleaching powder (Nalgonda technique) and adsorption using activated alumina. Use of aluminium compounds for water treatment purpose needs replacement on neurological health problem. Objective to this, the synthesis and

Soumen Dey; Saswati Goswami; Uday Chand Ghosh

2004-01-01

285

Selective hydrogenation of o-chloronitrobenzene over anatase-ferric oxides supported Ir nanocomposite catalyst.  

PubMed

The catalytic performance of Ir/TiO2-FeOx, an Ir/TiO2 catalyst modified with FeOx, was investigated for the hydrogenation of o-chloronitrobenzene, FeOx was found to promote both the activity and selectivity significantly. The initial reaction rate of Ir/TiO2-FeOx(10) nanocomposite catalyst was four times as high as that of Ir/TiO2 catalyst. Especially, the accumulation of intermediates was prohibited and finally 100% selectivity to o-chloroaniline was obtained at 100% conversion. Herein, we mainly discussed the promoting effect of FeOx with using the results of powder X-ray diffraction, transmission electron microscopy, element analysis mapping, hydrogen-temperature programmed reduction, hydrogen-temperature programmed desorption, diffuse reflectance infrared fourier transform spectra and X-ray photoelectron spectroscopy analysis. The FeOx was highly dispersed and a portion of FeO species existed in the Ir/TiO2-FeOx nanocomposite catalyst. Moreover, the FeOx was certified to have a strong interaction with Ir species, which should contribute to the excellent performance of the Ir/TiO2-FeOx nanocomposite catalyst. PMID:25086395

Lin, Weiwei; Zhao, Jia; Cheng, Haiyang; Li, Xiaoru; Li, Xiaonian; Zhao, Fengyu

2014-10-15

286

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

287

Estimation of surface precipitation constants for sorption of divalent metals onto hydrous ferric oxide and calcite  

E-print Network

+ , Mg2+ , Ca2+ , Mn2+ , Co2+ , Ni2+ , Sr2+ , Sn2+ , Ba2+ , Eu2+ , Ra2+ , Pb2+ , Hg2+ , Cu2+ , and UO2 2 estimation of free energies and, hence, equilibrium constants of the surface precipitation reactions for Be2

Polly, David

288

Standard test methods for pitting and crevice corrosion resistance of stainless steels and related alloys by use of ferric Chloride solution  

E-print Network

1.1 These test methods cover procedures for the determination of the resistance of stainless steels and related alloys to pitting and crevice corrosion (see Terminology G 15) when exposed to oxidizing chloride environments. Six procedures are described and identified as Methods A, B, C, D, E, and F. 1.1.1 Method A—Ferric chloride pitting test. 1.1.2 Method B—Ferric chloride crevice test. 1.1.3 Method C—Critical pitting temperature test for nickel-base and chromium-bearing alloys. 1.1.4 Method D—Critical crevice temperature test for nickel-base and chromium-bearing alloys. 1.1.5 Method E—Critical pitting temperature test for stainless steels. 1.1.6 Method F—Critical crevice temperature test for stainless steels. 1.2 Method A is designed to determine the relative pitting resistance of stainless steels and nickel-base, chromium-bearing alloys, whereas Method B can be used for determining both the pitting and crevice corrosion resistance of these alloys. Methods C, D, E and F allow for a rankin...

American Society for Testing and Materials. Philadelphia

2003-01-01

289

Consumption of hydrogen-rich water protects against ferric nitrilotriacetate-induced nephrotoxicity and early tumor promotional events in rats.  

PubMed

The aim of this work was to test whether consumption with hydrogen-rich water (HW) alleviated renal injury and inhibited early tumor promotional events in Ferric nitrilotriacetate (Fe-NTA)-treated rats. Rats were injected with Fe-NTA solution (7.5mg Fe/kg body weight) intraperitoneally to induce renal injury and simultaneously treated with HW (1.3 ± 0.2mg/l). We found that consumption with HW ameliorated Fe-NTA-induced renal injuries including suppressing elevation of serum creatinine and blood urea nitrogen and inhibited early tumor promotional events including decreasing ornithine decarboxylase activity and incorporation of [3H]thymidine into renal DNA. Consumption with HW suppressed Fe-NTA-induced oxidative stress through decreasing formation of lipid peroxidation and peroxynitrite and activities of NADPH oxidase and xanthine oxidase, increasing activity of catalase, and restoring mitochondrial function in kidneys. Consumption with HW suppressed Fe-NTA-induced inflammation marked by reduced NF-?B, IL-6, and MCP-1 expression and macrophage accumulating in kidneys. In addition, consumption with HW suppressed VEGF expression, STAT3 phosphorylation and PCNA expression in kidneys of Fe-NTA-treated rats. Consumption with HW decreased the incidence of renal cell carcinoma and suppressed tumor growth in Fe-NTA-treated in rats. In conclusion, drinking with HW attenuated Fe-NTA-induced renal injury and inhibited early tumor promotional events in rats. PMID:24140467

Li, Fang-Yin; Zhu, Shao-Xing; Wang, Zong-Ping; Wang, Hua; Zhao, Yang; Chen, Gui-Ping

2013-11-01

290

Ferric citrate spans mineral metabolism and anemia domains in ESRD: a review of efficacy and safety data.  

PubMed

Ferric citrate (Zerenex™, Keryx Biopharmaceuticals, Inc.), a phosphate binder drug candidate, recently completed a Phase III program confirming efficacy and demonstrating safety when used to treat hyperphosphatemia in patients with end-stage renal disease. Results of these trials demonstrate that ferric citrate effectively controls serum phosphorus and is well tolerated. Additionally, these studies demonstrate that ferric citrate improves iron parameters and reduces IV iron and erythropoietin stimulating agent utilization while maintaining hemoglobin levels. These unique features may further benefit the management of end-stage renal disease-related anemia. PMID:25242077

Sinsakul, Marvin; Rodby, Roger; Umanath, Kausik; Niecestro, Robert; Dwyer, Jamie P

2014-11-01

291

13C NMR signal detection of iron-bound cyanide ions in ferric cyanide complexes of heme proteins.  

PubMed

13CN ion appears to have the greatest potential to probe the heme environment of the ferric heme proteins; however, a resonance of the iron-bound (13)CN ion in ferric heme proteins has not yet been located. We show here the first detection of (13)C NMR signals of the iron-bound (13)CN for heme proteins and their model complexes in an unexpectedly large upfield region. This study demonstrates that the (13)C NMR signal of the iron-bound (13)CN is a sensitive probe to study the nature of the proximal ligand in ferric heme protein. PMID:12022815

Fujii, Hiroshi

2002-05-29

292

Low Temperature Photo-Oxidation of Chloroperoxidase Compound II  

PubMed Central

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

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

2010-01-01

293

Ferric iron uptake in Erwinia chrysanthemi mediated by chrysobactin and related catechol-type compounds.  

PubMed Central

Erwinia chrysanthemi 3937 possesses a saturable, high-affinity transport system for the ferric complex of its native siderophore chrysobactin, [N-alpha-(2,3-dihydroxybenzoyl)-D-lysyl-L-serine]. Uptake of 55Fe-labeled chrysobactin was completely inhibited by respiratory poison or low temperature and was significantly reduced in rich medium. The kinetics of chrysobactin-mediated iron transport were determined to have apparent Km and Vmax values of about 30 nM and of 90 pmol/mg.min, respectively. Isomers of chrysobactin and analogs with progressively shorter side chains mediated ferric iron transport as efficiently as the native siderophore, which indicates that the chrysobactin receptor primarily recognizes the catechol-iron center. Free ligand in excess only moderately reduced the accumulation of 55Fe. Chrysobactin may therefore be regarded as a true siderophore for E. chrysanthemi. PMID:1624465

Persmark, M; Expert, D; Neilands, J B

1992-01-01

294

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

PubMed

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

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

2013-11-19

295

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

Microsoft Academic Search

Wet-chemical and āµā·Fe Mossbauer analyses of ferrous\\/ferric ratios in complex borosilicate and simple silicate glasses were compared. The results support the validity of the colorimetric wet-chemical procedure and establish a linear calibration for the Mossbauer data. The resulting correlation indicates that using area ratios from Mossbauer spectra will overestimate the proportion of ferrous iron by a factor of 1.2. The

DON S. GOLDMAN; DEBORAH E. BEWLEY

1985-01-01

296

Using graphene nano-flakes as electrodes to remove ferric ions by capacitive deionization  

Microsoft Academic Search

In this work, the graphene nano-flakes (GNFs), with superior specific surface area and conductivity which are beneficial to electrosorption, were fabricated as electrodes for capacitive deionization devices. GNFs were prepared by a modified Hummers’ method with hydrazine for reduction and GNF electrodes were employed in electrosorption of ferric chloride (FeCl3). The morphology, structure, porous and electrochemical properties were characterized by

Haibo Li; Linda Zou; Likun Pan; Zhuo Sun

2010-01-01

297

Kinetic Modeling of Arsenic Removal From Water by Ferric Ion Loaded Red Mud  

Microsoft Academic Search

A laboratory study was conducted to investigate the ability of ferric ion loaded red mud (FRM) for the removal of arsenic species from water. The adsorbent material was characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. For an initial arsenic concentration lower than 0.3 mg\\/L, the FRM with a dosage of 1 g\\/L was able to reduce As(III)

Züleyha Özlem Kocaba?; Yuda Yürüm

2011-01-01

298

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

PubMed Central

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

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

2013-01-01

299

Chemical Treatment of Dairy Manure Using Alum, Ferric Chloride and Lime  

Microsoft Academic Search

Chemical treatment of dairy manure with alum (Al2(SO)4)3), ferric chloride (FeCl3) and lime is capable of achieving good solid-liquid separation and concentrating phosphorus (P) in the solid phase. Batch level jar tests conducted using dairy manure containing 0.8 % and 1.6% total solids (TS) indicate that very high removal (>90%) of dissolved reactive P (DRP), total dissolved P (TDP) and

K. G. Karthikeyan; Mehari Z. Tekeste; Mahmoud Kalbasi; Kerem Gungor

300

Clarification of municipal sewage with ferric chloride: the nature of coagulant species  

Microsoft Academic Search

The nature of coagulant species formed in the system ferric chloride\\/municipal sewage was explored with Transmission Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (TEM-EDXS) and Fe K-edge X-ray Absorption spectroscopy. Jar-test data combined with chemical analysis of supernatant (dissolved organic carbon, iron, and phosphorus) and Fourier-Transform-Infrared spectroscopy (FTIR) of freeze-dried sediment, provided a detailed description of sewage clarification. The

A. G. El Samrani; B. S. Lartiges; E. Montargčs-Pelletier; V. Kazpard; O. Barrčs; J. Ghanbaja

2004-01-01

301

A New Porcelain Repair System with a Silane Coupler, Ferric Chloride, and Adhesive Opaque Resin  

Microsoft Academic Search

A new porcelain repair system was developed which uses a two-liquid primer, self-cured opaque resin, and light-cured composite. The primer consisted of two liquids. One component was 4% 3-trimethoxysilylpropyl methacrylate in methyl methacrylate, and the other component was 0.5% ferric chloride in ethanol. A self-curing opaque resin, 4-META\\/MMA-TBB opaque resin, was used as an adhesive to bind the porcelain and

H. Matsumura; M. Kawahara; T. Tanaka; M. Atsuta

1989-01-01

302

Orthophosphate Removal from a Synthetic Wastewater Using Lime, Alum, and Ferric Chloride  

Microsoft Academic Search

Lime, alum, and ferric chloride were evaluated using a series of jar tests to determine their effectiveness in Orthophosphate precipitation from synthetic wastewaters. Calcium phosphate precipitation was most efficient at pH 11.0 and a total carbonate to phosphorus, CT:P, molar ratio of 15.0. For these conditions, a residual total Orthophosphate concentration of 0.12 mg\\/L-P was observed. The Mg:P molar ratio

Lynn Sisk; Larry Benefield; Bruce Reed

1987-01-01

303

A Bordetella pertussis fepA homologue required for utilization of exogenous ferric enterobactin  

Microsoft Academic Search

~~ The bfeA (Bodetella ferric enterobactin) receptor gene was cloned from a Bodetella pertussis chromosomal library by using a screen in Escherichia coli to detect iron-repressed genes encoding exported proteins translationally fused to the E. coliphoA gene. The bfeA gene encoded a protein with a molecular mass of approximately 80 kDa and about 50% amino acid sequence identity to both

Bernard Beall; Gary N. Sanden

1995-01-01

304

Intrinsic biodegradation of toluene coupled to the microbial reduction of ferric iron: laboratory column experiments  

Microsoft Academic Search

Intrinsic biodegradation of toluene coupled with the microbial reduction of ferric iron (Fe(III)) as the terminal electron acceptor was studied by using laboratory column experiments under continuous flow conditions. Columns were packed with contaminated aquifer sediment and N2-purged groundwater taken from the western part of the Gardermoen aquifer. The columns were operated anaerobically at 8 °C (in-situ temperature). Chloride was

Zuoping Zheng; Per Aagaard; Gijs D. Breedveld

2002-01-01

305

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

306

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

PubMed Central

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

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

2013-01-01

307

Olfactory ferric and ferrous iron absorption in iron-deficient rats  

PubMed Central

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

Ruvin Kumara, V. M.

2012-01-01

308

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

SciTech Connect

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

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

1994-01-01

309

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

Microsoft Academic Search

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

Seth Rose; W. Crawford Elliott

2000-01-01

310

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

311

Ferric Iron Precipitation in the Nagahama Bay, Satsuma Iwo-Jima Island, Kagoshima  

NASA Astrophysics Data System (ADS)

Satsuma-Iwojima island is active volcanic island and 6 x 3 km in size, located 38km south of Kyushu island, Japan. The reddish brown water along the coast of the Iwo-dake volcano at the center of the island formed by neutralization through mixing of shallow hydrothermal fluid and seawater. The reddish brown water contains reddish ferrihydrite (Fe3+) that is derived from oxidation of Fe2+ from acidic hot spring (Shikaura and Tazaki, 2001). In the Nagahama Bay with its opening to the south, red-colored Fe-rich water is affected by tidal current, but sedimentation of the ferric hydroxide is confirmed to occur in the ocean bottom (Ninomiya and Kiyokawa, 2009). Here we focus other lines of evidence from long term observations and meteorological records as important factor to form thick iron rich sediments. Meteorological and stationary observations: We used weather record in the Satsuma Iwo-jima and cross-checked with stationary observations, which enabled us to observe color changes of the surface of Nagahama Bay. It was made clear that north wind condition in the Nagahama Bay resulted in changes of the color of its surface, from red to green, by intrusion of ocean water coming from outside. Long term temperature monitoring: The temperature of seawater in the Nagahama Bay fluctuated synchronically with the air temperature. But that of hot spring water rather remained constant regardless of the seasonal change. We observed that seawater temperature in the Nagahama Bay is low at high tide and high at low tide, and the rage of temperature change is maximum at the spring tide and minimum at the neap tide. In other words, the amount of discharge of hot spring and that of seawater inflow vary inversely. Core sample: In the Nagahama Bay, iron rich sediments that is more than 1 m thick were identified. The core sample shows lithology as following; upper part, 10-20cm thick, formed loose Fe-rich deposit, lower portion formed alteration of weakly consolidated Fe-rich orange-colored mud, the organic-rich black mud and volcanic ash layers. The basal part has distinctive pink ash layer, which was identified as 1997 volcanic activity. Therefore, the core samples have records of the past 12 years and show average deposition rate of 8cm/year. Sediment trap: There accumulated 7.5cm-thick materials, dominated by ferrihydrite, during the 82 days experiment (2009/July/12~Oct./03). Sedimentation rate is 2.8cm/month (33.3cm/year). Estimated deposition rate of the core sample is 8cm/year. These differences suggest that about three-forth of Fe-hydroxide formed the Nagahama Bay would have been flashed to the open ocean by tidal and storm effects. These lines of evidence suggest that neap tide supports relatively quiet and has enough supply of hot spring into seawater and south wind works as a cap. The fine-grained iron Fe-hydroxide in the Nagahama Bay is provided and deposited at neap tide and south wind condition.

Nagata, T.; Kiyokawa, S.; Ikehara, M.; Oguri, K.; Goto, S.; Ito, T.; Yamaguchi, K. E.; Ueshiba, T.

2010-12-01

312

Effects of sulfur containing amino acids on iron and nitric oxide stimulated catecholamine oxidation  

Microsoft Academic Search

Summary.  ?Taurine is a free amino acid found in high concentrations in tissues containing catecholamines. The ability of taurine and\\u000a its metabolic precursors to inhibit or stimulate catecholamine oxidation and subsequent quinone formation was examined. Ferric\\u000a chloride was used as the catalyzing agent to stimulate L-dopa or norepinephrine oxidation and NO donors were also examined\\u000a for their actions to stimulate quinone

M. Biasetti; R. Dawson Jr.

2002-01-01

313

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

PubMed Central

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

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

1991-01-01

314

Oxidation modes and thermodynamics of oxyhydroxycarbonate green rust: dissolution-precipitation  

E-print Network

-stoichiometric magnetite Fe(3-x)O4 and goethite is observed for lower oxidation rates. The intermediate Fe oxidation accounts for the variation of ferric molar fraction x = [FeIII ]/{[FeII ]+[FeIII ]} observed substances, (ii) an upper mineral layer that can reach two meters deep getting ochre progressively

Paris-Sud XI, UniversitƩ de

315

Non-heme iron hydroperoxo species in superoxide reductase as a catalyst for oxidation reactions.  

PubMed

The non-heme high-spin ferric iron hydroperoxo species formed in superoxide reductase catalyzes oxidative aldehyde deformylation through its nucleophilic character. This species also acts as an electrophile to catalyze oxygen atom transfer in sulfoxidation reactions, highlighting the oxidation potential of non-heme iron hydroperoxo species. PMID:25283601

Rat, S; Ménage, S; Thomas, F; Nivičre, V

2014-10-21

316

Ferric carboxymaltose.  

PubMed

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, call The Formulary at 800-322-4349. The January 2014 monograph topics are obinutuzumab, anti-inhibitor coagulant complex, macitentan, riociguat, and conjugated estrogens/bazedoxifene. The DUE/MUE is on conjugated estrogens/bazedoxifene. PMID:24421564

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

2014-01-01

317

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

PubMed

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

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

1991-10-01

318

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

PubMed Central

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

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

1999-01-01

319

Iron oxide coatings on sand grains from the Atlantic coastal plain: High-resolution transmission electron microscopy characterization  

NASA Astrophysics Data System (ADS)

Nanoscale characterization of so-called iron oxide coatings on aquifer sands is vital for understanding the fate and transport of naturally occurring and anthropogenic chemical species. These coatings, which typically have a strong reddish color, are commonly assumed to consist primarily of iron oxides and oxyhydroxides. This work shows that the yellowish red to strong brown coatings on sediments from an Atlantic coastal plain aquifer in Virginia are predominantly a mixture of Si- and Al-rich nanophases of variable crystallinity with interspersed smectite and agglomerates of goethite nanoparticles. Clusters of bacterial cells, diatom fossils, sponge spicules, and other trace minerals are also observed.

Penn, R. L.; Zhu, C.; Xu, H.; Veblen, D. R.

2001-09-01

320

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

E-print Network

We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car-Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT+U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexa-aqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe-O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe-O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.

P. H. -L. Sit; Matteo Cococcioni; Nicola Marzari

2007-01-12

321

Ferric Citrate Hydrate as a Phosphate Binder and Risk of Aluminum Toxicity  

PubMed Central

Ferric citrate hydrate was recently approved in Japan as an oral phosphate binder to be taken with food for the control of hyperphosphatemia in patients with chronic kidney disease (CKD). The daily therapeutic dose is about 3 to 6 g, which comprises about 2 to 4 g of citrate. Oral citrate solubilizes aluminum that is present in food and drinking water, and opens the tight junctions in the intestinal epithelium, thereby increasing aluminum absorption and urinary excretion. In healthy animals drinking tap water, oral citrate administration increased aluminum absorption and, over a 4-week period, increased aluminum deposition in brain and bone by about 2- and 20-fold, respectively. Renal excretion of aluminum is impaired in patients with chronic kidney disease, thereby increasing the risk of toxicity. Based on human and animal studies it can be surmised that patients with CKD who are treated with ferric citrate hydrate to control hyperphosphatemia are likely to experience enhanced absorption of aluminum from food and drinking water, thereby increasing the risk of aluminum overload and toxicity. PMID:25341358

Gupta, Ajay

2014-01-01

322

Histoplasma capsulatum secreted ?-glutamyltransferase reduces iron by generating an efficient ferric reductant  

PubMed Central

Summary The intracellular fungal pathogen Histoplasma capsulatum (Hc) resides in mammalian macrophages and causes respiratory and systemic disease. Iron limitation is an important host antimicrobial defense, and iron acquisition is critical for microbial pathogenesis. Hc displays several iron acquisition mechanisms, including secreted glutathione-dependent ferric reductase activity (GSH-FeR). We purified this enzyme from culture supernatant and identified a novel extracellular iron reduction strategy involving ?-glutamyltransferase (Ggt1) activity. The 320-kDa complex was composed of glycosylated protein subunits of about 50 and 37 kDa. The purified enzyme exhibited ?-glutamyl transfer activity as well as iron reduction activity in the presence of glutathione. We cloned and manipulated expression of the encoding gene. Overexpression or RNAi silencing affected both GGT and GSH-FeR activities concurrently. Enzyme inhibition experiments showed the activity is complex and involves two reactions. First, Ggt1 initiates enzymatic breakdown of GSH by cleavage of the ?-glutamyl bond and release of cysteinylglycine. Second, the thiol group of the released dipeptide reduces ferric to ferrous iron. A combination of kinetic properties of both reactions resulted in efficient iron reduction over a broad pH range. Our findings provide novel insight into Hc iron acquisition strategies and reveal a unique aspect of Ggt1 function in this dimorphic mycopathogen. PMID:18761625

Zarnowski, Robert; Cooper, Kendal G.; Brunold, Laura Schmitt; Calaycay, Jimmy; Woods, Jon P.

2008-01-01

323

Species distribution of ferric hydrolysates in microwave enhanced Fenton-like process and possible mechanism.  

PubMed

In the present work, the investigations were firstly focused on the effect of microwave on the species distribution of ferric hydrolysates, as well as the effect of hydrolysates speciation on the treatment efficiency of organic compounds in the process of coagulation. A ferron-complexation timed spectrophotometric method was used to classify the Fe(III) speciation under different reaction conditions. Effects of microwave power, initial pH and reaction temperature on species distribution were intensively investigated. When microwave power and initial pH were 300 W and 5, respectively, the amount of high polymeric ferric species, so-called Fe(c), reached its maximum. The increment of reaction temperature resulted in an increasing formation of Fe(c), and microwave was able to generate more Fe(c) than that of thermostatic method at the same temperature. Comparing with the treatment of pharmaceutical wastewater, the results indicated that Fe(c) facilitated the net rolling-sweep action for organic molecules in coagulation process, which enhanced the removal efficiency of entire reaction system. PMID:20185232

Yang, Yu; Wang, Peng; Liu, Yuan

2010-06-15

324

Ferric citrate hydrate as a phosphate binder and risk of aluminum toxicity.  

PubMed

Ferric citrate hydrate was recently approved in Japan as an oral phosphate binder to be taken with food for the control of hyperphosphatemia in patients with chronic kidney disease (CKD). The daily therapeutic dose is about 3 to 6 g, which comprises about 2 to 4 g of citrate. Oral citrate solubilizes aluminum that is present in food and drinking water, and opens the tight junctions in the intestinal epithelium, thereby increasing aluminum absorption and urinary excretion. In healthy animals drinking tap water, oral citrate administration increased aluminum absorption and, over a 4-week period, increased aluminum deposition in brain and bone by about 2- and 20-fold, respectively. Renal excretion of aluminum is impaired in patients with chronic kidney disease, thereby increasing the risk of toxicity. Based on human and animal studies it can be surmised that patients with CKD who are treated with ferric citrate hydrate to control hyperphosphatemia are likely to experience enhanced absorption of aluminum from food and drinking water, thereby increasing the risk of aluminum overload and toxicity. PMID:25341358

Gupta, Ajay

2014-01-01

325

Synovectomy of the rheumatoid knee using intra-articular injection of dysprosium-165-ferric hydroxide macroaggregates  

SciTech Connect

One hundred and eleven patients who had seropositive rheumatoid arthritis and persistent synovitis of the knee were treated with intra-articular injection of 270 millicuries of dysprosium-165 bound to ferric hydroxide macroaggregates. A two-year follow-up was available for fifty-nine of the treated knees. Thirty-nine had a good result; nine, a fair result; and eleven, a poor result. Of the twenty-five knees that had Stage-I radiographic changes, nineteen had a good result. Of the thirty-four knees that had Stage-II radiographic changes, twenty showed a good result. Systemic spread of the radioactivity from the injected joint was minimum. The mean whole-body dose was calculated to be 0.3 rad and that to the liver twenty-four hours after injection, 3.2 rads. The results indicated that dysprosium-165-ferric hydroxide macroaggregate is an effective agent for performing radiation synovectomy, particularly in knees that have Stage-I radiographic changes. Because of the minimum rate of systemic spread of the dysprosium-165, it offers a definite advantage over agents that previously have been used.

Sledge, C.B.; Zuckerman, J.D.; Shortkroff, S.; Zalutsky, M.R.; Venkatesan, P.; Snyder, M.A.; Barrett, W.P.

1987-09-01

326

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

SciTech Connect

One hundred eight knees of 93 patients with seropositive rheumatoid arthritis and persistent synovitis of the knee were treated with an intraarticular injection of 270 mCi of dysprosium 165 bound to ferric hydroxide macroaggregate. Leakage of radioactivity from the injected joint was minimal. Mean leakage to the venous blood 3 hours after injection was 0.11% of the injected dose; this corresponds to a mean whole body dose of 0.2 rads. Mean leakage to the liver 24 hours after injection was 0.64% of the injected dose; this corresponds to a mean liver dose of 3.2 rads. In 7 additional patients examined, there was negligible or near negligible activity found in the draining inguinal lymph nodes. One-year followup was possible for 74 knees (63 patients). Sixty-one percent of the knees had good results, 23% had fair results, and 16% had poor results. There was a direct correlation between the radiographic stage and response to treatment. In knees with stage I radiographic changes, 72% showed good results; 93% showed improvement. In knees with stage II changes, 59% showed good results; 81% showed improvement. These preliminary results indicate that dysprosium 165-ferric hydroxide macroaggregate is an effective agent for radiation synovectomy. The low leakage rates observed offer a definite advantage over agents previously used.

Sledge, C.B.; Zuckerman, J.D.; Zalutsky, M.R.; Atcher, R.W.; Shortkroff, S.; Lionberger, D.R.; Rose, H.A.; Hurson, B.J.; Lankenner, P.A. Jr.; Anderson, R.J.

1986-02-01

327

Identification and Characterization of a Novel-type Ferric Siderophore Reductase from a Gram-positive Extremophile*  

PubMed Central

Iron limitation is one major constraint of microbial life, and a plethora of microbes use siderophores for high affinity iron acquisition. Because specific enzymes for reductive iron release in Gram-positives are not known, we searched Firmicute genomes and found a novel association pattern of putative ferric siderophore reductases and uptake genes. The reductase from the schizokinen-producing alkaliphile Bacillus halodurans was found to cluster with a ferric citrate-hydroxamate uptake system and to catalyze iron release efficiently from Fe[III]-dicitrate, Fe[III]-schizokinen, Fe[III]-aerobactin, and ferrichrome. The gene was hence named fchR for ferric citrate and hydroxamate reductase. The tightly bound [2Fe-2S] cofactor of FchR was identified by UV-visible, EPR, CD spectroscopy, and mass spectrometry. Iron release kinetics were determined with several substrates by using ferredoxin as electron donor. Catalytic efficiencies were strongly enhanced in the presence of an iron-sulfur scaffold protein scavenging the released ferrous iron. Competitive inhibition of FchR was observed with Ga(III)-charged siderophores with Ki values in the micromolar range. The principal catalytic mechanism was found to couple increasing Km and KD values of substrate binding with increasing kcat values, resulting in high catalytic efficiencies over a wide redox range. Physiologically, a chromosomal fchR deletion led to strongly impaired growth during iron limitation even in the presence of ferric siderophores. Inductively coupled plasma-MS analysis of ?fchR revealed intracellular iron accumulation, indicating that the ferric substrates were not efficiently metabolized. We further show that FchR can be efficiently inhibited by redox-inert siderophore mimics in vivo, suggesting that substrate-specific ferric siderophore reductases may present future targets for microbial pathogen control. PMID:21051545

Miethke, Marcus; Pierik, Antonio J.; Peuckert, Florian; Seubert, Andreas; Marahiel, Mohamed A.

2011-01-01

328

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

E-print Network

'O x O O? o o ~O O I O O M M M ( O ? O C'l O --O I I + 1 O O I' DI. '&CUSSIQN Comparison o& the by-products formed by the condensation o. 2-methylpropene . . 'th benzene in the presence of anhydro:s ferric chloride - it!! those... . mer. CONCLUSIONS 1. When benzene is alkylated with 2-methylpropene in the presence of ferric chloride the following hydrocarbons can be identified among the products of the reaction: t-butylbenzene, t-amylbenzene, t-hexylbenzene, l-isopropy1-3-t...

Mommessin, Pierre Robert

2012-06-07

329

Influence of ferric oxyhydroxide addition on biomethanation of waste activated sludge in a continuous reactor.  

PubMed

This study investigated the potential of enhancing the activity of iron-reducing bacteria (IRBs) to increase the biomethanation rate of waste activate sludge (WAS). The effects of biostimulation by ferric oxyhydroxide (Phase 2) and bioaugmentation with an enriched IRB consortium (Phase 3) were examined in a continuous anaerobic reactor treating WAS. Compared to the control operation (Phase 1), significant rises in methane yield (10.8-59.4%) and production rate (24.5-52.9%) were demonstrated by the biostimulation and bioaugmentation treatments. Visible structural changes were observed in bacterial community with the phases while not in archaeal community. Acinetobacter- and Spirochaetales-related populations were likely the major players driving anaerobic iron respiration and thus leading to enhanced biomethanation performance, in Phases 2 and 3, respectively. Our results suggest an interesting new potential for enhancing biomethanation of WAS. PMID:24929299

Baek, Gahyun; Kim, Jaai; Lee, Changsoo

2014-08-01

330

X-ray Spectroscopic Study of Solvent Effects on the Ferrous and Ferric Hexacyanide Anions.  

PubMed

We present an Fe K? resonant inelastic X-ray scattering (RIXS) and X-ray emission (XES) study of ferrous and ferric hexacyanide dissolved in water and ethylene glycol. We observe that transitions below the absorption edge show that the solvent has a distinct effect on the valence electronic structure. In addition, both the RIXS and XES spectra show a stabilization of the 2p levels when dissolved in water. Using molecular dynamics simulations, we propose that this effect arises from the hydrogen-bonding interactions between the complex and nearby solvent molecules. This withdraws electron density from the ligands, stabilizing the complex but also causing a slight increase in ?-backbonding. PMID:25223627

Penfold, T J; Reinhard, M; Rittmann-Frank, M H; Tavernelli, I; Rothlisberger, U; Milne, C J; Glatzel, P; Chergui, M

2014-10-01

331

Ferric sulphate catalysed esterification of free fatty acids in waste cooking oil.  

PubMed

In this work, the esterification of free fatty acids (FFA) in waste cooking oil catalysed by ferric sulphate was studied as a pre-treatment step for biodiesel production. The effects of reaction time, methanol to oil ratio, catalyst concentration and temperature on the conversion of FFA were investigated on a laboratory scale. The results showed that the conversion of FFA reached equilibrium after an hour, and was positively dependent on the methanol to oil molar ratio and temperature. An optimum catalyst concentration of 2 wt.% gave maximum FFA conversion of 59.2%. For catalyst loadings of 2 wt.% and below, this catalysed esterification was proposed to follow a pseudo-homogeneous pathway akin to mineral acid-catalysed esterification, driven by the H(+) ions produced through the hydrolysis of metal complex [Fe(H(2)O)(6)](3+) (aq). PMID:20435468

Gan, Suyin; Ng, Hoon Kiat; Ooi, Chun Weng; Motala, Nafisa Osman; Ismail, Mohd Anas Farhan

2010-10-01

332

The siderophore-interacting protein YqjH acts as a ferric reductase in different iron assimilation pathways of Escherichia coli.  

PubMed

Siderophore-interacting proteins (SIPs), such as YqjH from Escherichia coli, are widespread among bacteria and commonly associated with iron-dependent induction and siderophore utilization. In this study, we show by detailed biochemical and genetic analyses the reaction mechanism by which the YqjH protein is able to catalyze the release of iron from a variety of iron chelators, including ferric triscatecholates and ferric dicitrate, displaying the highest efficiency for the hydrolyzed ferric enterobactin complex ferric (2,3-dihydroxybenzoylserine)(3). Site-directed mutagenesis revealed that residues K55 and R130 of YqjH are crucial for both substrate binding and reductase activity. The NADPH-dependent iron reduction was found to proceed via single-electron transfer in a double-displacement-type reaction through formation of a transient flavosemiquinone. The capacity to reduce substrates with extremely negative redox potentials, though at low catalytic rates, was studied by displacing the native FAD cofactor with 5-deaza-5-carba-FAD, which is restricted to a two-electron transfer. In the presence of the reconstituted noncatalytic protein, the ferric enterobactin midpoint potential increased remarkably and partially overlapped with the effective E(1) redox range. Concurrently, the observed molar ratios of generated Fe(II) versus NADPH were found to be ~1.5-fold higher for hydrolyzed ferric triscatecholates and ferric dicitrate than for ferric enterobactin. Further, combination of a chromosomal yqjH deletion with entC single- and entC fes double-deletion backgrounds showed the impact of yqjH on growth during supplementation with ferric siderophore substrates. Thus, YqjH enhances siderophore utilization in different iron acquisition pathways, including assimilation of low-potential ferric substrates that are not reduced by common cellular cofactors. PMID:22098718

Miethke, Marcus; Hou, Jie; Marahiel, Mohamed A

2011-12-20

333

Perturbation-response scanning reveals ligand entry-exit mechanisms of ferric binding protein.  

PubMed

We study apo and holo forms of the bacterial ferric binding protein (FBP) which exhibits the so-called ferric transport dilemma: it uptakes iron from the host with remarkable affinity, yet releases it with ease in the cytoplasm for subsequent use. The observations fit the "conformational selection" model whereby the existence of a weakly populated, higher energy conformation that is stabilized in the presence of the ligand is proposed. We introduce a new tool that we term perturbation-response scanning (PRS) for the analysis of remote control strategies utilized. The approach relies on the systematic use of computational perturbation/response techniques based on linear response theory, by sequentially applying directed forces on single-residues along the chain and recording the resulting relative changes in the residue coordinates. We further obtain closed-form expressions for the magnitude and the directionality of the response. Using PRS, we study the ligand release mechanisms of FBP and support the findings by molecular dynamics simulations. We find that the residue-by-residue displacements between the apo and the holo forms, as determined from the X-ray structures, are faithfully reproduced by perturbations applied on the majority of the residues of the apo form. However, once the stabilizing ligand (Fe) is integrated to the system in holo FBP, perturbing only a few select residues successfully reproduces the experimental displacements. Thus, iron uptake by FBP is a favored process in the fluctuating environment of the protein, whereas iron release is controlled by mechanisms including chelation and allostery. The directional analysis that we implement in the PRS methodology implicates the latter mechanism by leading to a few distant, charged, and exposed loop residues. Upon perturbing these, irrespective of the direction of the operating forces, we find that the cap residues involved in iron release are made to operate coherently, facilitating release of the ion. PMID:19851447

Atilgan, Canan; Atilgan, Ali Rana

2009-10-01

334

Acidibacter ferrireducens gen. nov., sp. nov.: an acidophilic ferric iron-reducing gammaproteobacterium.  

PubMed

An acidophilic gammaproteobacterium, isolated from a pit lake at an abandoned metal mine in south-west Spain, was shown to be distantly related to all characterized prokaryotes, and to be the first representative of a novel genus and species. Isolate MCF85 is a Gram-negative, non-motile, rod-shaped mesophilic bacterium with a temperature growth optimum of 32-35 °C (range 8-45 °C). It was categorized as a moderate acidophile, growing optimally at pH 3.5-4.0 and between pH 2.5 and 4.5. Under optimum conditions its culture doubling time was around 75 min. Only organic electron donors were used by MCF85, and the isolate was confirmed to be an obligate heterotroph. It grew on a limited range of sugars (hexoses and disaccharides, though not pentoses) and some other small molecular weight organic compounds, and growth was partially or completely inhibited by small concentrations of some aliphatic acids. The acidophile grew in the presence of >100 mM ferrous iron or aluminium, but was more sensitive to some other metals, such as copper. It was also much more tolerant of arsenic (V) than arsenic (III). Isolate MCF85 catalysed the reductive dissolution of the ferric iron mineral schwertmannite when incubated under micro-aerobic or anaerobic conditions, causing the culture media pH to increase. There was no evidence, however, that the acidophile could grow by ferric iron respiration under strictly anoxic conditions. Isolate MCF85 is the designated type strain of the novel species Acidibacter ferrireducens (=DSM 27237(T) = NCCB 100460(T)). PMID:25116055

Falagįn, Carmen; Johnson, D Barrie

2014-11-01

335

Role of ferric reductases in iron acquisition and virulence in the fungal pathogen Cryptococcus neoformans.  

PubMed

Iron acquisition is critical for the ability of the pathogenic yeast Cryptococcus neoformans to cause disease in vertebrate hosts. In particular, iron overload exacerbates cryptococcal disease in an animal model, defects in iron acquisition attenuate virulence, and iron availability influences the expression of major virulence factors. C. neoformans acquires iron by multiple mechanisms, including a ferroxidase-permease high-affinity system, siderophore uptake, and utilization of both heme and transferrin. In this study, we examined the expression of eight candidate ferric reductase genes and their contributions to iron acquisition as well as to ferric and cupric reductase activities. We found that loss of the FRE4 gene resulted in a defect in production of the virulence factor melanin and increased susceptibility to azole antifungal drugs. In addition, the FRE2 gene was important for growth on the iron sources heme and transferrin, which are relevant for proliferation in the host. Fre2 may participate with the ferroxidase Cfo1 of the high-affinity uptake system for growth on heme, because a mutant lacking both genes showed a more pronounced growth defect than the fre2 single mutant. A role for Fre2 in iron acquisition is consistent with the attenuation of virulence observed for the fre2 mutant. This mutant also was defective in accumulation in the brains of infected mice, a phenotype previously observed for mutants with defects in high-affinity iron uptake (e.g., the cfo1 mutant). Overall, this study provides a more detailed view of the iron acquisition components required for C. neoformans to cause cryptococcosis. PMID:24478097

Saikia, Sanjay; Oliveira, Debora; Hu, Guanggan; Kronstad, James

2014-02-01

336

Effect of natural dissolved organic carbon on phosphate removal by ferric chloride and aluminum sulfate treatment of wetland waters  

Microsoft Academic Search

The use of wetlands for the removal of excess N and P has become widespread. Some sensitive P-limited ecosystems, however, may require additional reductions in the concentration of P entering the system. It has been proposed that the treatment of wetlands through addition of ferric chloride or aluminum sulfate can augment the natural P removal mechanisms. However, high concentrations of

Robert G. Qualls; Lindsay J. Sherwood; Curtis J. Richardson

2009-01-01

337

Enhanced anaerobic biodegradation of BTEX-ethanol mixtures in aquifer columns amended with sulfate, chelated ferric iron or nitrate  

E-print Network

, chelated ferric iron or nitrate Marcio L.B. Da Silva1 , Graciela M.L. Ruiz-Aguilar2 & Pedro J.J. Alvarez1Ā­Fe(III) or nitrate to enhance the biodegradation of BTEX and ethanol mixtures. The rapid biodegradation of ethanolĀ­Fe(III) or nitrate suppressed methanogenesis and significantly increased BTEX biodegradation efficiencies. Nev

Alvarez, Pedro J.

338

Antiproliferative Ability of Ferric-Sorbitol-Citrate and Ferrocenes for Malignant Cell Line, Hep2 and F10  

Microsoft Academic Search

Control of tumour cell growth through perturbation of cellular iron metabolism is a potentially important strategy in the treatment of cancer and thus warrants continued investigation. The Ferric-sorbitol-citrate (Jectofer) and tested ferrocenes are very interesting in that fields because of their specific antitumour effect and they could be further tested and submitted as a new antitumour substances.

M. Poljak-Blazi; A. Vidovic; V. Rapic; D. Škare

339

Simple Relationships among Zeta Potential, Particle Size Distribution, and Cake Specific Resistance for Colloid Suspensions Coagulated with Ferric Chloride  

Microsoft Academic Search

Kaolinite and latex colloidal suspensions were coagulated with various doses of ferric chloride before being filtered on microfiltration membranes. Subsequent improvements of the filtration rate (7 to 25 times) were observed for small coagulant doses (10 to 20 mg Fe\\/g). The variations of three parameters, the cake specific resistance, the particle interaction energy calculated from zeta potential measurements, and the

M. Hlavacek; J. F. Remy

1995-01-01

340

Preparation and coagulation efficiency of polyaluminium ferric silicate chloride composite coagulant from wastewater of high-purity graphite production  

Microsoft Academic Search

The aim of the present work was to produce a polyaluminium ferric silicate chloride (PAFSiC) coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation efficiency of the reagent by treating surface water from the Yellow River as well as municipal wastewater in comparison with the conventional coagulant polyaluminium chloride (PAC). The PAFSiC coagulant

Xiaoxia Niu; Xili Li; Jihong Zhao; Yigang Ren; Yanqin Yang

2011-01-01

341

Magnetic and EPR study of ferric green rust- and ferrihydrite-coated sand prepared by different synthesis routes  

Microsoft Academic Search

Due to increased active surface area and high redox flexibility, the green rust- and ferrihydrite- (FH) coated sands appear promising materials in environmental applications such as reactive filtration processes for the elimination and fixation of pollutants in soils, sediments and contaminated water. Recently, different synthesis routes to prepare coatings of the ferric green rust (FGR) and FH minerals on quartz

Magdalena Wencka; Andreja Jelen; Marko Jagodic; Varsha Khare; Christian Ruby; Janez Dolinsek

2009-01-01

342

Chronic use of sodium ferric gluconate complex in hemodialysis patients: Safety of higher-dose (?250 mg) administration  

Microsoft Academic Search

Background: Almost all hemodialysis (HD) patients require intravenous iron therapy to correct their anemia and maintain their iron stores. Sodium ferric gluconate complex (SFGC) is approved by the Food and Drug Administration (FDA) for treatment of iron deficiency anemia in HD patients at individual doses up to 125 mg over 10 minutes (12.5 mg\\/min) and has been shown to have

Vaughn W. Folkert; Beckie Michael; Rajiv Agarwal; Daniel W. Coyne; Naomi Dahl; Pamela Myirski; David G. Warnock

2003-01-01

343

Shallow-water hydrothermal system and sedimentation of the ferric deposit in the Nagahama-bay, Satsuma Iwo-jima Island  

NASA Astrophysics Data System (ADS)

Satsuma Iwo-jima Island, located 40km south of Kyushu, Japan, has characteristic hydrothermal activities surrounding its active volcano Iwo-dake. Along the shoreline, hydrothermal fluids discharge and they cause discoloration of the seawater. At Nagahama-bay, iron ion in carbonated spring is oxidized to iron hydroxide precipitate by mixing with the sea water and the water takes on red color(Kamada, 1964). To understand the relationships among the ferric deposits, hydrothermal ventings, and the sea tide in the bay, we conducted the following studies; (a) naked eye observation at seafloor by SCUBA diving and the measurements of temperature and sediment distributions, (b) time-series in situ observation of the sesafloor by OGURI-View system (an automatic underwater digital camera system; Oguri et al., 2006), (c) time-series observation of color changes in the surface water by automatic acquisition system modified from OGURI-View, (d) geochemical analysis of the sea water collected in spring and fall 2007 and summer 2008, (e) coring to find the components in the sediment, and (f) six months-long sediment trap to estimate total mass flux in the bay. On the seafloor, numerous hot vents were found in the eastern part of the bay at 4m in depth. Soft sediment was also formed around the vents up to 1.5m thick. Temperature of the surface sediment ranged from 30 to 55 degree Celsius; the highest temperature was observed near those vents. The time-series images taken by OGURI-View system showed that turbidness of the bottom of the sea water changed daily. The turbidity data in the bay indicated that their daily changes occurred by tidal currents and sometimes by unusual mixing induced by strong typhoon. The sediment of 83cm core sample consisted of clay-sized reddish ferric oxides, quartz, volcanic ashes, rock fragments, and very fine to fine sand. From the sediment trap experiment, total mass accumulation rate was estimated to 0.12-0.18g/cm2/day. This high rate may be one factor contributing to the thick sediment.

Ninomiya, T.; Kiyokawa, S.; Koge, S.; Oguri, K.; Yamaguchi, K. E.; Ito, T.; Ikehara, M.

2008-12-01

344

The effect of titanium and phosphorus on ferric/ferrous ratio in silicate melts: an experimental study  

NASA Astrophysics Data System (ADS)

The effect of TiO2 and P2O5 on the ferric/ferrous ratio in silicate melts was investigated in model silicate melts at air conditions in the temperature range 1,400-1,550 °C at 1-atm total pressure. The base composition of the anorthite-diopside eutectic composition was modified with 10 wt % Fe2O3 and variable amounts of TiO2 (up to 30 wt %) or P2O5 (up to 20 wt %). Some compositions also contained higher SiO2 concentrations to compare the role of SiO2, TiO2, and P2O5 on the Fe3+/Fe2+ ratio. The ferric/ferrous ratio in experimental glasses was analyzed using a wet chemical technique with colorimetric detection of ferrous iron. It is shown that at constant temperature, an increase in SiO2, TiO2, and P2O5 content results in a decrease in the ferric/ferrous ratio. The effects of TiO2 and SiO2 on the Fe3+/Fe2+ ratio was found to be almost identical. In contrast, adding P2O5 was found to decrease ferric/ferrous ratio much more effectively than adding silica. The results were compared with the predictions from the published empirical equations forecasting Fe3+/Fe2+ ratio. It was demonstrated that the effects of TiO2 are minor but that the effects of P2O5 should be included in models to better describe ferric/ferrous ratio in phosphorus-bearing silicate melts. Based on our observations, the determination of the prevailing fO2 in magmas from the Fe3+/Fe2+ ratio in natural glasses using empirical equations published so far is discussed critically.

Borisov, Alexander; Behrens, Harald; Holtz, Francois

2013-12-01

345

A Silica/Fly Ash-Based Technology for Controlling Pyrite Oxidation  

SciTech Connect

The purpose of our studies during this past six-month period was to evaluate the surface properties of iron-oxide-silicate coatings. The specific objectives were (a) to evaluate the mechanisms and ability of hydrous ferric oxide (HFO) to adsorb silica (Si); (b) to evaluate the effects of Si on the bulk and surface properties of HFO; and (c) to evaluate the effect of Si on heavy-metal adsorption properties by iron-oxides.

V. P. Evangelou

1997-04-14

346

Catalytic performance and deactivation of precipitated iron catalyst for selective oxidation of hydrogen sulfide to elemental sulfur in the waste gas streams from coal gasification  

SciTech Connect

The selective oxidation of hydrogen sulfide to elemental sulfur, using a commercial, precipitated silica promoted ferric oxide based catalyst, was investigated in laboratory and pilot-plant reactors. Low levels of hydrogen sulfide (1-3 vol%) can be readily removed, but a continuous slow decrease in catalyst activity was apparent. X-ray photoelectron spectroscopy showed that the loss of activity was due to the formation of ferrous sulfate, which is known to be less active than the ferric oxide. In addition, studies using a model feed showed that the propene and HCN impurities in the plant feed stocks also act as potent catalyst poisons.

Mashapa, T.N.; Rademan, J.D.; van Vuuren, M.J.J. [Sasol Technology Research & Development, Sasolburg (South Africa)

2007-09-15

347

Solar physical vapor deposition preparation and microstructural characterization of TiO2 based nanophases for dye-sensitized solar cell applications.  

PubMed

Titanium dioxide exists in three crystalline phases: anatase, rutile and brookite. Although rutile is thermodynamically more stable, anatase is considered as the most favorable phase for photocatalysis and solar energy conversion. Recent studies have shown a significant improvement of light harvesting and overall solar conversion efficiency of anatase nanoparticles in dye-sensitized solar cells (DSSCs) when using a mixture of anatase and rutile phases (10-15% rutile). TiO2 nanopowders have been prepared by a solar physical vapor deposition process (SPVD). This method has been developed in Odeillo-Font Romeu France using "heliotron" solar reactors working under concentrated sunlight in 2 kW solar furnaces. By controlling reactor's atmosphere type (air/argon) and gas pressure, several types of anatase/rutile nanophases have been obtained with slightly different microstructural properties and morphological characteristics. X-ray diffraction analyses (XRD) were performed on precursor and on the SPVD obtained nanopowders. Information concerning their phase composition and coherence diffraction domain (crystallites size and strain) was obtained. Nanopowders morphology has been studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). PMID:23421278

Negrea, Denis; Ducu, Catalin; Moga, Sorin; Malinovschi, Viorel; Monty, Claude J A; Vasile, Bogdan; Dorobantu, Dorel; Enachescu, Marian

2012-11-01

348

Ultrafiltration evaluation with depleted uranium oxide  

SciTech Connect

Scientists at the Los Alamos National Laboratory Plutonium Facility are using electrodissolution in neutral to alkaline solutions to decontaminate oralloy parts that have surface plutonium contamination. Ultrafiltration of the electrolyte stream removes precipitate so that the electrolyte stream to the decontamination fixture is precipitate free. This report describes small-scale laboratory ultrafiltration experiments that the authors performed to determine conditions necessary for full-scale operation of an ultrafiltration module. Performance was similar to what they observed in the ferric hydroxide system. At 12 psi transmembrane pressure, a shear rate of 12,000 sec{sup {minus}1} was sufficient to sustain membrane permeability. Ultrafiltration of uranium(VI) oxide appears to occur as easily as ultrafiltration of ferric hydroxide. Considering the success reported in this study, the authors plan to add ultrafiltration to the next decontamination system for oralloy parts.

Weisbrod, K.R.; Schake, A.R.; Morgan, A.N.; Purdy, G.M.; Martinez, H.E.; Nelson, T.O.

1998-03-01

349

Mineral leaching, iron precipitation, and the sulfate requirement for chemolithotrophic iron oxidation  

Microsoft Academic Search

The leaching of pyrite by Thiobacillus ferrooxidans results in formation of an aqueous Fe(III) sulfato complex that leaches pyrite and precipitates excess iron sulfate. However, until recently most general texts stated that the deposits formated by bacterial leaching of pyrite consited of ferric hydroxide, implying that the massive presence of sulfate played no role in the oxidation or precipitation of

Norman Lazaroff

1997-01-01

350

Removal of As(V) using iron oxide impregnated carbon prepared from Tamarind hull  

Microsoft Academic Search

Iron oxide impregnated tamarind hull carbon (IOITHC) was developed for use as an adsorbent for the removal of As(V) from water. Tamarind hull was used as the source of carbonaceous material, which was first treated with ferric chloride and ammonium hydroxide solutions with successive calcination at 873–974 K in a muffle furnace for 1 h to prepare an arsenic adsorbent.

Abhijit Maiti; Vaibhav Agarwal; Sirshendu De; Jayanta K. Basu

2010-01-01

351

Characterization and Localization of Iron-Oxidizing Proteins in Acid Mine Drainage Biofilms  

Microsoft Academic Search

As molecular geomicrobiologists, we are interested in the microbially-produced molecules that effect geochemical transformations, particularly proteins involved in lithotrophic energy generation. We have identified two such proteins produced by Leptospirillum group II microbes, which dominate biofilms floating on acidic waters in the Richmond Mine at Iron Mountain, CA. Leptospirillum generates energy by iron oxidation, producing the ferric iron catalyst responsible

C. S. Chan; M. P. Thelen; M. Hwang; J. F. Banfield

2005-01-01

352

The Enzyme-mimic Activity of Ferric Nano-Core Residing in Ferritin and Its Biosensing Applications  

SciTech Connect

Ferritins are nano-scale globular protein cages encapsulating a ferric core. They widely exist in animals, plants, and microbes, playing indispensable roles in iron homeostasis. Interestingly, our study clearly demonstrates that ferritin has an enzyme-mimic activity derived from its ferric nano-core, but not the protein cage. Further study revealed that the mimic-enzyme activity of ferritin is more thermally stable and pH-tolerant compared with horseradish peroxidase. Considering the abundance of ferritin in numerous organisms, this finding may indicate a new role of ferritin in antioxidant and detoxification metabolisms. In addition, as a natural protein-caged nanoparticle with an enzyme-mimic activity, ferritin is readily conjugated with biomolecules to construct nano-biosensors, thus holds promising potential for facile and biocompatible labeling for sensitive and robust bioassays in biomedical applications.

Tang, Zhiwen; Wu, Hong J.; Zhang, Youyu; Li, Zhaohui; Lin, Yuehe

2011-11-15

353

Evaluation of formocresol, calcium hydroxide, ferric sulfate, and MTA primary molar pulpotomies  

PubMed Central

Objective: The aim of this study is to evaluate four different pulpotomy medicaments in primary molars. Materials and Methods: A total of 147 primary molars with deep caries were treated with four different pulpotomy medicaments (FC: formocresol, FS: ferric sulfate, CH: calcium hydroxide, and MTA: mineral trioxide aggregate) in this study. The criteria for tooth selection for inclusion were no clinical and radiographic evidence of pulp pathology. During 30 months of follow-up at 6-month intervals, clinical and radiographic success and failures were recorded. The differences between the groups were statistically analyzed using the Chi-square test and Kaplan-Meier analysis. Results: At 30 months, clinical success rates were 100%, 95.2%, 96.4%, and 85% in the FC, FS, MTA, and CH groups, respectively. In radiographic analysis, the MTA group had the highest (96.4%), and the CH group had the lowest success rate (85%). There were no clinical and radiographic differences between materials (P > 0.05). Conclusions: Although there were no differences between materials, only in the CH group did three teeth require extraction due to further clinical symptoms of radiographic failures during the 30-month follow-up period. None of the failed teeth in the other groups required extraction during the 30-month follow-up period. PMID:24966776

Yildiz, Esma; Tosun, Gul

2014-01-01

354

Overproduction in Escherichia coli and Characterization of a Soybean Ferric Leghemoglobin Reductase.  

PubMed Central

We previously cloned and sequenced a cDNA encoding soybean ferric leghemoglobin reductase (FLbR), an enzyme postulated to play an important role in maintaining leghemoglobin in a functional ferrous state in nitrogen-fixing root nodules. This cDNA was sub-cloned into an expression plasmid, pTrcHis C, and overexpressed in Escherichia coli. The recombinant FLbR protein, which was purified by two steps of column chromatography, was catalytically active and fully functional. The recombinant FLbR cross-reacted with antisera raised against native FLbR purified from soybean root nodules. The recombinant FLbR, the native FLbR purified from soybean (Glycine max L.) root nodules, and dihydrolipoamide dehydrogenases from pig heart and yeast had similar but not identical ultraviolet-visible absorption and fluorescence spectra, cofactor binding, and kinetic properties. FLbR shared common structural features in the active site and prosthetic group binding sites with other pyridine nucleotide-disulfide oxidoreductases such as dihydrolipoamide dehydrogenases, but displayed different microenvironments for the prosthetic groups. PMID:12232320

Ji, L.; Becana, M.; Sarath, G.; Shearman, L.; Klucas, R. V.

1994-01-01

355

Ferric ions involved in the flower color development of the Himalayan blue poppy, Meconopsis grandis.  

PubMed

The Himalayan blue poppy, Meconopsis grandis, has sky blue-colored petals, although the anthocyanidin nucleus of the petal pigment is cyanidin. The blue color development in this blue poppy involving ferric ions was therefore studied. We analyzed the vacuolar pH, and the organic and inorganic components of the colored cells. A direct measurement by a proton-selective microelectrode revealed that the vacuolar pH value was 4.8. The concentrations of the total anthocyanins in the colored cells were around 5mM, and ca. three times more concentrated flavonols were detected. Fe was detected by atomic analysis of the colored cells, and the ratio of Fe to anthocyanins was ca. 0.8 eq. By mixing the anthocyanin, flavonol and metal ion components in a buffered aq. solution at pH 5.0, we were able to reproduce the same blue color; the visible absorption spectrum and CD were identical to those in the petals, with Fe(3+), Mg(2+) and flavonol being essential for the blue color. The blue pigment in Meconopsis should be a new type of metal complex pigment that is different from a stoichiometric supramolecular pigment such as commelinin or protocyanin. PMID:16678868

Yoshida, Kumi; Kitahara, Sayoko; Ito, Daisuke; Kondo, Tadao

2006-05-01

356

Ferric ammonium citrate-cellulose paste for opacification of the esophageal lumen on MRI  

SciTech Connect

A new ferric ammonium citrate-cellulose mixture for use in MRI of the esophagus was evaluated for its ability to opacify the esophageal lumen. Thirty-two patients with esophageal disorders and ten patients with normal esophagus undergoing MRI at 1.5 T were given {approx} 100 ml of the newly developed high-viscosity esophageal contrast preparation. Moreover, six of the patients with esophageal cancer were subjected to a second examination after radiation therapy. A total of 48 MR imaging were performed. Of the patients examined, successful esophageal opacification, graded as excellent, was obtained in 84.2, 78.9, and 57.9%, of the sagittal, axial, and coronal images, respectively. In cases of extrinsic disease involving the esophagus the contrast medium administration allowed the easy differentiation of the esophagus from adjacent mass lesions and proved very useful in identifying displacement and compression. In cases of esophageal carcinoma the contrast medium administration assisted in the measurement of wall thickness and length of the lesion as well as in the identification of the site of origin of the tumor. The results indicate that this product effectively specifies the esophageal lumen in the majority of patients. We found that it is easy to use, is well tolerated, and does not produce artifacts. 12 refs., 5 figs., 1 tab.

Ogawa, Yasuhiro; Noda, Yoshihiro; Morio, Kazuo [Kochi Medical School (Japan)] [and others] [Kochi Medical School (Japan); and others

1996-05-01

357

Passive immunization by recombinant ferric enterobactin protein (FepA) from Escherichia coli O157  

PubMed Central

Background and Objectives Enterohemorrhagic Escherichia coli (EHEC) O157:H7 has been recognized as a major food borne pathogen responsible for frequent hemorrhagic colitis and hemolytic uremic syndrome in humans. Cattle are important reservoirs of E. coli O157:H7, in which the organism colonizes the intestinal tract and is shed in the feces. Objective Vaccination of cattle has significant potential as a pre-harvest intervention strategy for E. coli O157:H7. The aim of this study was to evaluate active and passive immunization against E. coli O157:H7 using a recombinant protein. Materials and Methods The recombinant FepA protein induced by IPTG was purified by nickel affinity chromatography. Antibody titre was determined by ELISA in FepA immunized rabbits sera. Sera collected from vaccinated animals were used for bacterial challenge in passive immunization studies. Results The results demonstrate that passive immunization with serum raised against FepA protects rabbits from subsequent infection. Conclusion Significant recognition by the antibody of ferric enterobactin binding protein may lead to its application in the restriction of Enterobacteriaceae propagation. PMID:23825727

Larrie-Bagha, Seyed Mehdi; Rasooli, Iraj; Mousavi-Gargari, Seyed Latif; Rasooli, Zohreh; Nazarian, Shahram

2013-01-01

358

NMR reveals pathway for ferric mineral precursors to the central cavity of ferritin  

PubMed Central

Ferritin is a multimeric nanocage protein that directs the reversible biomineralization of iron. At the catalytic ferroxidase site two iron(II) ions react with dioxygen to form diferric species. In order to study the pathway of iron(III) from the ferroxidase site to the central cavity a new NMR strategy was developed to manage the investigation of a system composed of 24 monomers of 20 kDa each. The strategy is based on 13C-13C solution NOESY experiments combined with solid-state proton-driven 13C-13C spin diffusion and 3D coherence transfer experiments. In this way, 75% of amino acids were recognized and 35% sequence-specific assigned. Paramagnetic broadening, induced by iron(III) species in solution 13C-13C NOESY spectra, localized the iron within each subunit and traced the progression to the central cavity. Eight iron ions fill the 20-?-long iron channel from the ferrous/dioxygen oxidoreductase site to the exit into the cavity, inside the four-helix bundle of each subunit, contrasting with short paths in models. Magnetic susceptibility data support the formation of ferric multimers in the iron channels. Multiple iron channel exits are near enough to facilitate high concentration of iron that can mineralize in the ferritin cavity, illustrating advantages of the multisubunit cage structure. PMID:20018746

Turano, Paola; Lalli, Daniela; Felli, Isabella C.; Theil, Elizabeth C.; Bertini, Ivano

2010-01-01

359

The Regulatory Role of Ferric Uptake Regulator (Fur) during Anaerobic Respiration of Shewanella piezotolerans WP3  

PubMed Central

Ferric uptake regulator (Fur) is a global regulator that controls bacterial iron homeostasis. In this study, a fur deletion mutant of the deep-sea bacterium Shewanella piezotolerans WP3 was constructed. Physiological studies revealed that the growth rate of this mutant under aerobic conditions was only slightly lower than that of wild type (WT), but severe growth defects were observed under anaerobic conditions when different electron acceptors (EAs) were provided. Comparative transcriptomic analysis demonstrated that Fur is involved not only in classical iron homeostasis but also in anaerobic respiration. Fur exerted pleiotropic effects on the regulation of anaerobic respiration by controlling anaerobic electron transport, the heme biosynthesis system, and the cytochrome c maturation system. Biochemical assays demonstrated that levels of c-type cytochromes were lower in the fur mutant, consistent with the transcriptional profiling. Transcriptomic analysis and electrophoretic mobility shift assays revealed a primary regulation network for Fur in WP3. These results suggest that Fur may act as a sensor for anoxic conditions to trigger and influence the anaerobic respiratory system. PMID:24124499

Yang, Xin-Wei; He, Ying; Xu, Jun; Xiao, Xiang; Wang, Feng-Ping

2013-01-01

360

Permeability properties of a large gated channel within the ferric enterobactin receptor, FepA.  

PubMed Central

FepA is an Escherichia coli outer membrane receptor protein for the siderophore ferric enterobactin. Prior studies conducted in vivo suggested that FepA and other TonB-dependent outer membrane proteins transport ligands by a gated-channel mechanism. To corroborate and extend these findings we have determined the permeability properties of the FepA channel in vitro, by measuring the diffusion rates of hydrophilic nonelectrolytes through the FepA channel in liposome swelling experiments. Like porins, the FepA deletion mutant delta RV showed a size-dependent permeability to oligosaccharides, indicating that it forms a nonspecific, hydrophilic pore. Unlike OmpF and other E. coli porins, however, delta RV proteoliposomes transported stachyose (666 Da) and ferrichrome (740 Da). These data, and other uptake results with a series of maltodextrins of increasing size, confirm the existence of a channel domain within FepA that is considerably larger than OmpF-type pores. These results represent a reconstitution of the channel function of a TonB-dependent receptor protein and establish that FepA contains the largest channel that has been characterized in the E. coli outer membrane. Images Fig. 1 PMID:7504275

Liu, J; Rutz, J M; Feix, J B; Klebba, P E

1993-01-01

361

Glutathione-dependent extracellular ferric reductase activities in dimorphic zoopathogenic fungi  

PubMed Central

In this study, extracellular glutathione-dependent ferric reductase (GSH-FeR) activities in different dimorphic zoopathogenic fungal species were characterized. Supernatants from Blastomyces dermatitidis, Histoplasma capsulatum, Paracoccidioides brasiliensis and Sporothrix schenckii strains grown in their yeast form were able to reduce iron enzymically with glutathione as a cofactor. Some variations in the level of reduction were noted amongst the strains. This activity was stable in acidic, neutral and slightly alkaline environments and was inhibited when trivalent aluminium and gallium ions were present. Using zymography, single bands of GSH-FeRs with apparent molecular masses varying from 430 to 460 kDa were identified in all strains. The same molecular mass range was determined by size exclusion chromatography. These data demonstrate that dimorphic zoopathogenic fungi produce and secrete a family of similar GSH-FeRs that may be involved in the acquisition and utilization of iron. Siderophore production by these and other fungi has sometimes been considered to provide a full explanation of iron acquisition in these organisms. Our work reveals an additional common mechanism that may be biologically and pathogenically important. Furthermore, while some characteristics of these enzymes such as extracellular location, cofactor utilization and large size are not individually unique, when considered together and shared across a range of fungi, they represent an important novel physiological feature. PMID:16000713

Zarnowski, Robert; Woods, Jon P.

2009-01-01

362

Stage-1 intercalation compounds of few graphene layers by anhydrous ferric chloride  

NASA Astrophysics Data System (ADS)

Anhydrous ferric chloride (FeCl3) was used to intercalate few graphene layers into stage-1 intercalation compounds. The intercalant, staging, stability, and doping of the resulting intercalation compounds are characterized by Raman scattering. The G peak of pure stage-1 compounds upshifts to ˜1626 cm-1, which is similar to that of heavily-doped monolayer graphenes by 18M sulfuric acid. A single Lorentzian line shape for the 2D band of stage-1 compounds were observed, which indicates that each layer behaves as a decoupled heavily doped monolayer. By performing Raman measurements at different excitation energies, we show that, for a given doping level, the variation of the 2D intensity relative to the G peak with excitation energy allows one to assess the Fermi energy. This allows us to estimate a Fermi level shift of up to ˜0.85 eV, which agrees well with that estimated from the 2D/G intensity ratio and is close to ˜0.9 eV measured in stage-1 GICs by electron energy loss spectroscopy. The stage-1 intercalation compound of few graphene layers is thus ideal test-beds for the physical and chemical properties of heavily doped graphenes.

Tan, Pingheng; Zhao, Weijie; Liu, Jian; Ferrari, Andrea

2012-02-01

363

Preparation and Thermal Analysis of Ferric Doped PVA-PVP-PPy Composite Films  

NASA Astrophysics Data System (ADS)

The preparation and thermal analysis of flexible blend films of pyrrole (Py) polymerized in aqueous solution of poly (vinyl alcohol) (PVA) and poly (vinyl pyrrolidone) (PVP) is described. In-situ polymerization of pyrrole in aqueous solution of PVA and PVP containing ferric chloride (FeCl3) was achieved through vapor sorption, and the films obtained were studied using Differential Scanning Calorimetry (DSC), Thermo-Gravimetric Analysis (TGA) and Differential Thermal Analysis (DTA). No melting endotherm is seen in the DSC and DTA scans of the composite films, indicating that the sample is amorphous. Degradation of the sample is found to occur at lower temperatures, with increase in doping level (wt% of FeCl3). DSC study was performed between 40 °C and 400 °C. Below 1.2 wt % DL, degradation of the sample occurs in two stages, the first at 310 °C and the second at 440 °C, as seen from DTA and TGA scans. The broad endotherm between 80 °C and 120 °C is due to volatization of moisture (water) absorbed by the sample. Multiple endotherms are observed in DSC and DTA scans of the composite films, for FeCl3 doping levels above 3.8 wt %, and the sample degrades in many different stages at lower temperature, with increase in doping level, as revealed by weight losses in the TGA curve.

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

2011-12-01

364

Characterization of a Novel NADH-Specific, FAD-Containing, Soluble Reductase with Ferric Citrate Reductase Activity from Maize Seedlings  

Microsoft Academic Search

A novel NADH-dependent, soluble flavoreductase of 60 kDa, active toward ferric chelates and quinones, has been purified from maize seedlings. Two closely related isoforms were separated. The two isoforms are similar in several biochemical features, with the exception of the apparent molecular mass of their subunits (29 and 31 kDa, respectively). They are homodimers in the native state, they bind

Francesca Sparla; Valeria Preger; Paolo Pupillo; Paolo Trost

1999-01-01

365

Further characterization of ferric--phytosiderophore transporters ZmYS1 and HvYS1 in maize and barley  

Microsoft Academic Search

Roots of some gramineous plants secrete phytosiderophores in response to iron deficiency and take up Fe as a ferric-phytosiderophore complex through the transporter YS1 (Yellow Stripe 1). Here, this transporter in maize (ZmYS1) and barley (HvYS1) was further characterized and compared in terms of expression pattern, diurnal change, and tissue-type specificity of localization. The expression of HvYS1 was specifically induced

Daisei Ueno; Naoki Yamaji; Jian Feng Ma

2009-01-01

366

Occurrence and regulation of the ferric citrate transport system in Escherichia coli B, Klebsiella pneumoniae, Enterobacter aerogenes, and Photorhabdus luminescens  

Microsoft Academic Search

In Escherichia coli K-12, transcription of the ferric citrate transport genes fecABCDE is initiated by binding of diferric dicitrate to the outer membrane protein FecA which elicits a signaling cascade from the\\u000a cell surface to the cytoplasm. The FecI sigma factor is only active in the presence of FecR, which transfers the signal across\\u000a the cytoplasmic membrane. In other bacteria,

Susanne Mahren; Heidrun Schnell; Volkmar Braun

2005-01-01

367

Two Bifunctional Enzymes with Ferric Reduction Ability Play Complementary Roles during Magnetosome Synthesis in Magnetospirillum gryphiswaldense MSR-1  

PubMed Central

The bacterial strain Magnetospirillum gryphiswaldense MSR-1 does not produce siderophores, but it absorbs a large amount of ferric iron and synthesizes magnetosomes. We demonstrated previously the presence of six types of ferric reductase isozymes (termed FeR1 through FeR6) in MSR-1. Of these isozymes, FeR5 was the most abundant and FeR6 showed the highest ferric reductase activity. In the present study, we cloned the fer5 and fer6 genes from MSR-1 and expressed them separately in Escherichia coli. FeR5 and FeR6 were shown to be bifunctional enzymes through analysis of amino acid sequence homologies, structural predictions (using data from GenBank), and detection of enzyme activities. FeR5 is a thioredoxin reductase and FeR6 is a flavin reductase, in addition to being ferric reductases. To elucidate the functions of the enzymes, we constructed two single-gene-deletion mutant strains (?fer5 and ?fer6 mutants) and a double-gene-deletion mutant strain (?fer5 ?fer6 [?fer5+6] mutant) along with its complemented strains (C5 and C6). An evaluation of phenotypic and physiological properties did not reveal significant differences between the wild-type and single-gene-deletion strains, whereas the double-gene-deletion strain showed reduced iron absorption and no magnetosome synthesis. Complementation of the double-gene-deletion strain using either fer5 or fer6 resulted in the partial recovery of magnetosome synthesis. Quantitative real-time PCR analysis of fer5 and fer6 transcriptional levels in the wild-type and complemented strains demonstrated consistent transcription of the two genes and confirmed that FeR5 and FeR6 are bifunctional enzymes that play complementary roles during the process of magnetosome synthesis in MSR-1. PMID:23243303

Zhang, Chan; Meng, Xia; Li, Ningxiao; Wang, Wei; Sun, Yuan; Jiang, Wei; Guan, Guohua

2013-01-01

368

Selective detection of ferric ions by blue-green photoluminescent nitrogen-doped phenol formaldehyde resin polymer.  

PubMed

The smaller, the more fluorescent: The hydrothermal reaction of phenol with hexamethylenetetramine (HMT) leads to two morphologies of phenol formaldehyde resin (PFR), namely, bigger nanoparticles with feeble green fluorescence and smaller amorphous polymers with strong blue-green fluorescence. It reveals that both of them are doped with nitrogen, and the blue-green photoluminescent polymer is confirmed to sense ferric ion (Fe(3+) ) with high selectivity. PMID:24863556

Zhang, Jia; Yuan, Yue; Yu, Zhi-Long; Yu, Aimin; Yu, Shu-Hong

2014-09-24

369

Optimization of ferric chloride induced thrombosis model in rats: Effect of anti-platelet and anti-coagulant drugs  

Microsoft Academic Search

Numerous studies on various animal species, with variability in the site of application and the concentration of ferric chloride (FeCl3) to induce intravascular thrombosis has prompted us to undertake the present study to obtain a threshold concentration of FeCl3 and validate this model by clinically used anti-thrombotic drugs. A small piece of filter paper, soaked in FeCl3 solution (10, 20,

W. R. Surin; P. Prakash; M. K. Barthwal; M. Dikshit

2010-01-01

370

Surface complexation modeling of the removal of arsenic from ion-exchange waste brines with ferric chloride  

Microsoft Academic Search

Brine disposal is a serious challenge of arsenic (V) removal from drinking water using ion-exchange (IX). Although arsenic removal with ferric chloride (FeCl3) from drinking waters is well documented, the application of FeCl3 to remove arsenic (V) from brines has not been thoroughly investigated. In contrast to drinking water, IX brines contain high ionic strength, high alkalinity, and high arsenic

Behrang Pakzadeh; Jacimaria R. Batista

2011-01-01

371

Decomposition of a Mixed-Valence [2Fe-2S] Cluster to Linear Tetra-Ferric and Ferrous Clusters  

PubMed Central

Despite the ease of preparing di-ferric [2Fe-2S] clusters, preparing stable mixed-valence analogues remains a challenge, as these clusters have limited thermal stability. Herein we identify two decomposition products of the mixed-valence thiosalicylate-ligated [2Fe-2S] cluster, [Fe2S2(SArCOO)2]3? ((SArCOO)2? = thiosalicylate). PMID:23976815

Saouma, Caroline T.; Kaminsky, Werner; Mayer, James M.

2012-01-01

372

Sodium ferric gluconate complex in sucrose is safe and effective in hemodialysis patients: North American clinical trial  

Microsoft Academic Search

A new intravenous (IV) iron compound, sodium ferric gluconate complex in sucrose (Ferrlecit, R&D Laboratories, Inc, Marina Del Rey, CA), was administered over 8 consecutive dialysis days in equally divided doses to a total of either 0.5 or 1.0 g in a controlled, open, multicenter, randomized clinical study of anemic, iron-deficient hemodialysis patients receiving recombinant human erythropoietin (rHuEPO). Effectiveness was

Allen R. Nissenson; Robert M. Lindsay; Suzanne Swan; Paul Seligman; Jur Strobos

1999-01-01

373

Sodium ferric gluconate complex in hemodialysis patients. II. Adverse reactions in iron dextran-sensitive and dextran-tolerant patients  

Microsoft Academic Search

Sodium ferric gluconate complex in hemodialysis patients. II. Adverse reactions in iron dextran-sensitive and dextran-tolerant patients.BackgroundIron dextran administration is associated with a high incidence of adverse reactions including anaphylaxis and death. Although dextran, rather than iron, is believed to be the cause of these reactions, it is not known whether iron dextran-sensitive patients can be safely administered another form of

Daniel W Coyne; Franklin N Adkinson; Allen R Nissenson; Steven Fishbane; Rajiv Agarwal; Joseph W Eschbach; Beckie Michael; Vaughn Folkert; Daniel Batlle; J Richard Trout; Naomi Dahl; Pamela Myirski; Jur Strobos; David G Warnock

2003-01-01

374

Azide, cyanide, fluoride, imidazole and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative: A comparative study  

Microsoft Academic Search

Azide, cyanide, fluoride, imidazole, and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative has been investigated, from the thermodynamic viewpoint, at pH 7.5 and 25.0°C. Ligand affinity for ferric and ferrous carboxymethylated cytochrome c is higher by about 30- and 400-fold, respectively, than that observed for the native protein. The results here

Franca Viola; Silvio Aime; Massimo Coletta; Alessandro Desideri; Mauro Fasano; Silvia Paoletti; Cataldo Tarricone; Paolo Ascenzi

1996-01-01

375

Enargite oxidation: A review  

NASA Astrophysics Data System (ADS)

Enargite, Cu 3AsS 4, is common in some deposit types, e.g. porphyry systems and high sulphidation epithermal deposits. It is of environmental concern as a potential source of arsenic. In this communication, we review the current knowledge of enargite oxidation, based on the existing literature and our own original data. Explicit descriptions of enargite oxidation in natural environments are scarce. The most common oxidized alteration mineral of enargite is probably scorodite, FeAsO 4.2H 2O, with iron provided most likely by pyrite, a phase almost ubiquitously associated with enargite. Other secondary minerals after enargite include arsenates such as chenevixite, Cu 2Fe 2(AsO 4) 2(OH) 4.H 2O, and ceruleite, Cu 2Al 7(AsO 4) 4.11.5H 2O, and sulphates such as brochantite, Cu 4(SO 4)(OH) 6, and posnjakite, Cu 4(SO 4)(OH) 6·H 2O. Detailed studies of enargite field alteration at Furtei, Sardinia, suggest that most alteration occurs through dissolution, as testified by the appearance of etch pits at the surface of enargite crystals. However, apparent replacement by scorodite and cuprian melanterite was observed. Bulk oxidation of enargite in air is a very slow process. However, X-ray photoelectron spectroscopy (XPS) reveals subtle surface changes. From synchrotron-based XPS it was suggested that surface As atoms react very fast, presumably by forming bonds with oxygen. Conventional XPS shows the formation, on aged samples, of a nanometer-size alteration layer with an appreciably distinct composition with respect to the bulk. Mechanical activation considerably increases enargite reactivity. In laboratory experiments at acidic to neutral pH, enargite oxidation/dissolution is slow, although it is accelerated by the presence of ferric iron and/or bacteria such as Acidithiobacillus ferrooxidans and Sulfolobus BC. In the presence of sulphuric acid and ferric iron, the reaction involves dissolution of Cu and formation of native sulphur, subsequently partly oxidized to sulphate. At alkaline pH, the reactivity of enargite is apparently slightly greater. XPS spectra of surfaces conditioned at pH 11 have been interpreted as evidence of formation of a number of surface species, including cupric oxide and arsenic oxide. Treatment with hypochlorite solutions at pH 12.5 quickly produces a coating of cupric oxide. Electrochemical oxidation of enargite typically involves low current densities, confirming that the oxidation process is slow. Important surface changes occur only at high applied potentials, e.g. + 0.74 V vs. SHE. It is confirmed that, at acidic pH, the dominant process is Cu dissolution, accompanied (at + 0.56 V vs. SHE, pH = 1) by formation of native sulphur. At alkaline pH, a number of surface products have been suggested, including copper and arsenic oxides, and copper arsenates. XPS studies of the reacted surfaces demonstrate the evolution of Cu from the monovalent to the divalent state, the formation of As-O bonds, and the oxidation of sulphur to polysulphide, sulphite and eventually sulphate. In most natural and quasi-natural (mining) situations, it is expected that enargite reactivity will be slow. Moreover, it is likely that the release of arsenic will be further slowed down by at least temporary trapping in secondary phases. Therefore, an adequate management of exposed surfaces and wastes should minimize the environmental impact of enargite-bearing deposits. In spite of an increasing body of data, there are several gaps in our knowledge of enargite oxidation. The exact nature of most mechanisms and products remains poorly constrained, and there is a lack of quantitative data on the dependence on parameters such as pH and dissolved oxygen.

Lattanzi, Pierfranco; Da Pelo, Stefania; Musu, Elodia; Atzei, Davide; Elsener, Bernhard; Fantauzzi, Marzia; Rossi, Antonella

2008-01-01

376

Synthetic analogues of [Fe4S4(Cys)3(His)] in hydrogenases and [Fe4S4(Cys)4] in HiPIP derived from all-ferric [Fe4S4{N(SiMe3)2}4  

PubMed Central

The all-ferric [Fe4S4]4+ cluster [Fe4S4{N(SiMe3)2}4] 1 and its one-electron reduced form [1]- serve as convenient precursors for the synthesis of 3?1-site differentiated [Fe4S4] clusters and high-potential iron-sulfur protein (HiPIP) model clusters. The reaction of 1 with four equivalents (equiv) of the bulky thiol HSDmp (Dmp = 2,6-(mesityl)2C6H3, mesityl = 2,4,6-Me3C6H2) followed by treatment with tetrahydrofuran (THF) resulted in the isolation of [Fe4S4(SDmp)3(THF)3] 2. Cluster 2 contains an octahedral iron atom with three THF ligands, and its Fe(S)3(O)3 coordination environment is relevant to that in the active site of substrate-bound aconitase. An analogous reaction of [1]- with four equiv of HSDmp gave [Fe4S4(SDmp)4]- 3, which models the oxidized form of HiPIP. The THF ligands in 2 can be replaced by tetramethyl-imidazole (Me4Im) to give [Fe4S4(SDmp)3(Me4Im)] 4 modeling the [Fe4S4(Cys)3(His)] cluster in hydrogenases, and its one-electron reduced form [4]- was synthesized from the reaction of 3 with Me4Im. The reversible redox couple between 3 and [3]- was observed at E1/2 = -820 mV vs. Ag/Ag+, and the corresponding reversible couple for 4 and [4]- is positively shifted by +440 mV. The cyclic voltammogram of 3 also exhibited a reversible oxidation couple, which indicates generation of the all-ferric [Fe4S4]4+ cluster, [Fe4S4(SDmp)4]. PMID:21768339

Ohki, Yasuhiro; Tanifuji, Kazuki; Yamada, Norihiro; Imada, Motosuke; Tajima, Tomoyuki; Tatsumi, Kazuyuki

2011-01-01

377

Breakdown of Fe-Ringwoodite to Ferrosilite and Ferric Wadsleyite at high P and T and Oxidizing Conditions  

NASA Astrophysics Data System (ADS)

The stability relations in the systems M2SiO4 (M = Mg, Fe, Ni, Co) have been the subject of numerous studies because of their significance for the mantle transition zone. In the Mg2SiO4 system three polymporphs exist: at ambient conditions olivine, at pressure > 13 GPa ( 1000 °C) wadsleyite and at P > 18 GPa ( 1000 °C) ringwoodite. This is quite different to the Fe2SiO4 system where no intervending wadsleyite phase has been observed but fayalite directly transforms to Fe- ringwoodite at 5.3 GPa ( 1000 °C). Experiments in the system Fe2SiO4 Fe3O4 by Woodland and Angel (1998) at 5.6 GPa (1100 ° C) revealed that Fe-wadsleyite can only be stabilised if significant amounts of Fe3+ are incorporated leading to the formula Fe2.45Si0.55O4. To get deeper insight into the phase relation in the system Fe2SiO4 we investigated the phase relations as a function of P, T and fO2. The experiments were performed in a multi-anvil apparatus at 7 GPa and temperatures 1000 ° C. Oxygen fugacities were variied using the solid oxygen buffer systems Fe/FeO and Ni/NiO. The run products were analysed with electron microprobe, Raman spectroscopy, transmission electron microscopy including electron energy-loss spectroscopy and X-ray powder diffraction. The X-ray data were analysed using the GSAS software. At fO2 conditions corresponding to Fe/FeO Fe- ringwoodite is the stable phase with normal spinel structure. At fO2 between Fe/FeO and Ni/NiO the inversion grade and Fe3+ content of Fe-ringwoodite slightly increases leading to the formula (Fe1.96Si0.04)(Si0.95Fe0.05)O4. At fO2 corresponding to Ni/NiO fayalite transforms to ferrosilite and Fe-wadsleyite according to the reaction: 9 Fe2SiO4 + O2 = 6 FeSiO3 + 5 Fe2.42Si0.58O4. Refinement of site occupancies in combinations with stoichiometric Fe3+ calculations show that in wadsleyite 32 % of the total Fe is incorporated as Fe3+ according to Fe2+1.60Fe3+0.40Si0.62Fe3+0.38O4 whereas the ferrosilite seems to be free of Fe3+. Reference Woodland and Angel (1998) Crystal strucutre of a new spinelloid with the wadsleyite strucutre in the system Fe2SiO4 Fe3O4 and implications for the Earth's mantle. American Mineralogist 83, 404-408.

Koch-Müller, M.; Rhede, D.; Schulz, R.; Wirth, R.

2006-12-01

378

Neurotoxicity of low-dose repeatedly intranasal instillation of nano- and submicron-sized ferric oxide particles in mice  

Microsoft Academic Search

Olfactory tract has been demonstrated to be an important portal for inhaled solid nanoparticle transportation into the central nervous system (CNS). We have previously demonstrated that intranasally instilled Fe2O3 nanoparticles could transport into the CNS via olfactory pathway. In this study, we inves- tigated the neurotoxicity and size effect of repeatedly low-dose (130 lg) intranasal exposure of nano- and submicron-sized

Bing Wang; Weiyue Feng; Motao Zhu; Yun Wang; Meng Wang; Yiqun Gu; Hong Ouyang; Huajian Wang; Ming Li; Yuliang Zhao; Zhifang Chai; Haifang Wang

2008-01-01

379

Neurotoxicity of low-dose repeatedly intranasal instillation of nano- and submicron-sized ferric oxide particles in mice  

Microsoft Academic Search

Olfactory tract has been demonstrated to be an important portal for inhaled solid nanoparticle transportation into the central\\u000a nervous system (CNS). We have previously demonstrated that intranasally instilled Fe2O3 nanoparticles could transport into the CNS via olfactory pathway. In this study, we investigated the neurotoxicity and size\\u000a effect of repeatedly low-dose (130 ?g) intranasal exposure of nano- and submicron-sized Fe2O3 particles

Bing Wang; Weiyue Feng; Motao Zhu; Yun Wang; Meng Wang; Yiqun Gu; Hong Ouyang; Huajian Wang; Ming Li; Yuliang Zhao; Zhifang Chai; Haifang Wang

2009-01-01

380

Photocatalytic activity of ferric oxide/titanium dioxide nanocomposite films on stainless steel fabricated by anodization and ion implantation  

NASA Astrophysics Data System (ADS)

A simple surface treatment was used to develop photocatalytic activity for stainless steel. AISI 304 stainless steel specimens after anodization were implanted by Ti ions at an extracting voltage of 50 kV with an implantation dose of 3 × 1015 atoms·cm-2 and then annealed in air at 450°C for 2 h. The morphology was observed by scanning electron microscopy. The microstructure was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The photocatalytic degradation of methylene blue solution was carried out under ultraviolet light. The corrosion resistance of the stainless steel was evaluated in NaCl solution (3.5 wt%) by electrochemical polarization curves. It is found that the Ti ions depth profile resembles a Gaussian distribution in the implanted layer. The nanostructured Fe2O3/TiO2 composite film exhibits a remarkable enhancement in photocatalytic activity referenced to the mechanically polished specimen and anodized specimen. Meanwhile, the annealed Ti-implanted specimen remains good corrosion resistance.

Zhan, Wei-ting; Ni, Hong-wei; Chen, Rong-sheng; Yue, Gao; Tai, Jun-kai; Wang, Zi-yang

2013-08-01

381

Curcumin attenuates oxidative damage in animals treated with a renal carcinogen, ferric nitrilotriacetate (Fe-NTA): implications for cancer prevention  

Microsoft Academic Search

Curcumin (diferuloylmethane), a biologically active ingredient derived from rhizome of the plant Curcuma longa, has potent anticancer properties as demonstrated in a plethora of human cancer cell lines\\/animal carcinogenesis model and\\u000a also acts as a biological response modifier in various disorders. We have reported previously that dietary supplementation\\u000a of curcumin suppresses renal ornithine decarboxylase (Okazaki et al. Biochim Biophys Acta 1740:357–366,

Mohammad Iqbal; Yasumasa Okazaki; Shigeru Okada

2009-01-01

382

Growth, spectroscopic and physicochemical properties of bis mercury ferric chloride tetra thiocyanate: a nonlinear optical crystal.  

PubMed

Single crystal of bis mercury ferric chloride tetra thiocyanate [Hg2FeCl3(SCN)4; (MFCTC)] was grown from ethanol-water (3:1) mixed solvent using slow evaporation solvent technique (SEST) for the first time. The cell parameters of the grown crystal were confirmed by single crystal XRD. The coordination of transition metal ions with the SCN ligand is well-identified using FT-IR spectral analysis. The chemical composition of MFCTC was confirmed using CHNS elemental test. The ESR spectral profile of MFCTC was recorded from 298 K to 110K, which strongly suggests the incorporation of Fe(3+) ion and its environment with respect to SCN ligand. The HPLC chromatogram of MFCTC highlights the purity of the compound. The UV-Vis-NIR studies revealed the ultra violet cut-off wavelength of MFCTC in ethanol as 338 nm. The dielectric constant and dielectric loss of the sample were studied as a function of frequency and temperature. The TGA-DTA and DSC thermal analysis show that the sample is thermally stable up to 234.31 °C, which is comparatively far better than the thermal stability of Hg3CdCl2(SCN)6; (171.3 °C) and other metal-organic coordination complex crystals such as CdHg(SCN)4 (198.5 °C), Hg(N2H4CS)4Mn(SCN)4 (199.06 °C) and Hg(N2H4CS)4Zn(SCN)4 (185 °C). The SHG conversion efficiency of MFCTC is found to be higher than KDP. PMID:23501934

Ramesh, V; Shihabuddeen Syed, A; Jagannathan, K; Rajarajan, K

2013-05-01

383

Computational methods for intramolecular electron transfer in a ferrous-ferric iron complex  

SciTech Connect

The limitations of common theoretical and molecular computational approaches for predicting electron transfer quantities were assessed, using an archetypal bridged ferrous-ferric electron transfer system in aqueous solution. The basis set effect on the magnitude of the electronic coupling matrix element computed using the quasi-diabatic method was carefully examined, and it was found that the error related to a poor basis set could exceed the thermal energy at room temperature. A range of approaches to determining the external (solvent) reorganization energy were also investigated. Significant improvements from the Marcus continuum model can be obtained by including dipolar Born-Kirkwood-Onsager correction. In this regard we also found that Klamt’s Conductor-Like Screening Model (COSMO) yields estimations of the external reorganization energy similar to those obtained with explicit solvent molecular dynamics simulations, if the fast-frequency modes are neglected, which makes it an attractive alternative to laborious umbrella sampling simulations. As expected, dielectric saturation observed in the first solvation shell decreases the curvature of the potential energy surface, but it nonetheless remains a quadratic function of the reaction coordinate. The linearity of solvent response to the charge redistribution was assessed by analyzing the energy gap autocorrelation function as well as the solvent density and dipole moment fluctuations. Molecular dynamics was also used to evaluate the sign and magnitude of the solvent reorganization entropy, to determine its effect on the predicted electron transfer rate. Finally, we present a simple way of estimating the vibration frequency along the reaction coordinate, which also enables prediction of the mass dependent isotopic signature of electron-transfer reactions.

Zarzycki, Piotr P.; Kerisit, Sebastien N.; Rosso, Kevin M.

2011-07-29

384

The Porphyromonas gingivalis Ferric Uptake Regulator Orthologue Binds Hemin and Regulates Hemin-Responsive Biofilm Development  

PubMed Central

Porphyromonas gingivalis is a Gram-negative pathogen associated with the biofilm-mediated disease chronic periodontitis. P. gingivalis biofilm formation is dependent on environmental heme for which P. gingivalis has an obligate requirement as it is unable to synthesize protoporphyrin IX de novo, hence P. gingivalis transports iron and heme liberated from the human host. Homeostasis of a variety of transition metal ions is often mediated in Gram-negative bacteria at the transcriptional level by members of the Ferric Uptake Regulator (Fur) superfamily. P. gingivalis has a single predicted Fur superfamily orthologue which we have designated Har (heme associated regulator). Recombinant Har formed dimers in the presence of Zn2+ and bound one hemin molecule per monomer with high affinity (Kd of 0.23 µM). The binding of hemin resulted in conformational changes of Zn(II)Har and residue 97Cys was involved in hemin binding as part of a predicted -97C-98P-99L- hemin binding motif. The expression of 35 genes was down-regulated and 9 up-regulated in a Har mutant (ECR455) relative to wild-type. Twenty six of the down-regulated genes were previously found to be up-regulated in P. gingivalis grown as a biofilm and 11 were up-regulated under hemin limitation. A truncated Zn(II)Har bound the promoter region of dnaA (PGN_0001), one of the up-regulated genes in the ECR455 mutant. This binding decreased as hemin concentration increased which was consistent with gene expression being regulated by hemin availability. ECR455 formed significantly less biofilm than the wild-type and unlike wild-type biofilm formation was independent of hemin availability. P. gingivalis possesses a hemin-binding Fur orthologue that regulates hemin-dependent biofilm formation. PMID:25375181

Seers, Christine A.; Mitchell, Helen L.; Catmull, Deanne V.; Glew, Michelle D.; Heath, Jacqueline E.; Tan, Yan; Khan, Hasnah S. G.; Reynolds, Eric C.

2014-01-01

385

Interaction between ferric ions, phospholipid hydroperoxides, and the lipid phosphate moiety at physiological pH.  

PubMed

Iron-catalyzed lipid peroxidation was examined using 1H NMR in a biphasic aqueous-chloroform system. At physiological pH (7.4), mole ratios of phospholipids/Fe3+ as low as 1300:1 catalyzed the rapid disappearance of endogenous lipid hydroperoxides with a loss of two of the four double bonds in PC containing palmitic (16:0) and arachidonic (20:4) acids in the sn-1 and sn-2 positions, respectively. The predominant phospholipid products after 1 h at 20 degrees C were a 9-carbon mono-unsaturated carbonyl and a phospholipid with an 11-carbon delta5,8 FA in the sn-2 position. PC with linoleic acid (18:2) in the sn-2 position lost one double bond and formed a phospholipid with a 9-carbon FA. Cardiolipin (linoleic acid-rich) also lost about 40% of its double bonds. No detectable loss was seen for PC containing oleic acid (18:1) or neutral lipids with PUFA. At arachidonyl PC/Fe3+ ratios less than 20:1, significant broadening of the choline methyl proton peak was evident, indicating that Fe3+ may form a complex with the adjacent phosphate group and that the complex involves both the phosphate and the hydroperoxide adjacent to the delta11 double bond. The results demonstrate that, at physiological pH, Fe3+-catalyzed peroxidation in polyunsaturated phospholipids occurs selectively adjacent to specific double bonds (delta9 or delta11). These PC-derived products have been shown to activate components of the inflammatory system. This suggests that the episodic release of ferric ions may play a significant role in generating inflammatory mediators. PMID:15669764

Morrill, Gene A; Kostellow, Adele; Resnick, Lawrence M; Gupta, Raj K

2004-09-01

386

Effect of Ammonium and Nitrate on Ferric Chelate Reductase and Nitrate Reductase in Vaccinium Species  

PubMed Central

• Background and Aims Most Vaccinium species have strict soil requirements for optimal growth, requiring low pH, high iron availability and nitrogen primarily in the ammonium form. These soils are limited and are often located near wetlands. Vaccinium arboreum is a wild species adapted to a wide range of soils, including high pH, low iron, and nitrate?containing soils. This broader soil adaptation in V. arboreum may be related to increased efficiency of iron or nitrate uptake compared with the cultivated Vaccinium species. • Methods Nitrate, ammonium and iron uptake, and nitrate reductase (NR) and ferric chelate reductase (FCR) activities were compared in two Vaccinium species grown hydroponically in either nitrate or ammonia, with or without iron. The species studied were the wild V. arboreum and the cultivated V. corymbosum interspecific hybrid, which exhibits the strict soil requirements of most Vaccinium species. • Key Results Ammonium uptake was significantly greater than nitrate uptake in both species, while nitrate uptake was greater in the wild species, V. arboreum, compared with the cultivated species, V. corymbosum. The increased nitrate uptake in V. arboreum was correlated with increased root NR activity compared with V. corymbosum. The lower nitrate uptake in V. corymbosum was reflected in decreased plant dry weight in this species compared with V. arboreum. Root FCR activity increased significantly in V. corymbosum grown under iron?deficient conditions, compared with the same species grown under iron?sufficient conditions or with V. arboreum grown under either iron condition. • Conclusions. V. arboreum appears to be more efficient in acquiring nitrate compared with V. corymbosum, possibly due to increased NR activity and this may partially explain the wider soil adaptation of V. arboreum. PMID:14980973

POONNACHIT, U.; DARNELL, R.

2004-01-01

387

Functional characterization of the dimerization domain of the ferric uptake regulator (Fur) of Pseudomonas aeruginosa  

PubMed Central

The functional properties of the recombinant C-terminal dimerization domain of the Pseudomonas aeruginosa Fur (ferric uptake regulator) protein expressed in and purified from Escherichia coli have been evaluated. Sedimentation velocity measurements demonstrate that this domain is dimeric, and the UV CD spectrum is consistent with a secondary structure similar to that observed for the corresponding region of the crystallographically characterized wild-type protein. The thermal stability of the domain as determined by CD spectroscopy decreases significantly as pH is increased and increases significantly as metal ions are added. Potentiometric titrations (pH 6.5) establish that the domain possesses a high-affinity and a low-affinity binding site for metal ions. The high-affinity (sensory) binding site demonstrates association constants (KA) of 10(±7)×106, 5.7(±3)×106, 2.0(±2)×106 and 2.0(±3)×104 M?1 for Ni2+, Zn2+, Co2+ and Mn2+ respectively, while the low-affinity (structural) site exhibits association constants of 1.3(±2)×106, 3.2(±2)×104, 1.76(±1)×105 and 1.5(±2)×103 M?1 respectively for the same metal ions (pH 6.5, 300 mM NaCl, 25 °C). The stability of metal ion binding to the sensory site follows the Irving–Williams order, while metal ion binding to the partial sensory site present in the domain does not. Fluorescence experiments indicate that the quenching resulting from binding of Co2+ is reversed by subsequent titration with Zn2+. We conclude that the domain is a reasonable model for many properties of the full-length protein and is amenable to some analyses that the limited solubility of the full-length protein prevents. PMID:16928194

Bai, Erdeni; Rosell, Federico I.; Lige, Bao; Mauk, Marcia R.; Lelj-Garolla, Barbara; Moore, Geoffrey R.; Mauk, A. Grant

2006-01-01

388

Clinical experience with ferric carboxymaltose in the treatment of cancer- and chemotherapy-associated anaemia  

PubMed Central

Background Intravenous (i.v.) iron can improve anaemia of chronic disease and response to erythropoiesis-stimulating agents (ESAs), but data on its use in practice and without ESAs are limited. This study evaluated effectiveness and tolerability of ferric carboxymaltose (FCM) in routine treatment of anaemic cancer patients. Patients and methods Of 639 patients enrolled in 68 haematology/oncology practices in Germany, 619 received FCM at the oncologist's discretion, 420 had eligible baseline haemoglobin (Hb) measurements, and 364 at least one follow-up Hb measurement. Data of transfused patients were censored from analysis before transfusion. Results The median total iron dose was 1000 mg per patient (interquartile range 600–1500 mg). The median Hb increase was comparable in patients receiving FCM alone (1.4 g/dl [0.2–2.3 g/dl; N = 233]) or FCM + ESA (1.6 g/dl [0.7–2.4 g/dl; N = 46]). Patients with baseline Hb up to 11.0 g/dl and serum ferritin up to 500 ng/ml benefited from FCM treatment (stable Hb ?11.0 g/dl). Also patients with ferritin >500 ng/ml but low transferrin saturation benefited from FCM treatment. FCM was well tolerated, 2.3% of patients reported putative drug-related adverse events. Conclusions The substantial Hb increase and stabilisation at 11–12 g/dl in FCM-treated patients suggest a role for i.v. iron alone in anaemia correction in cancer patients. PMID:23071262

Steinmetz, T.; Tschechne, B.; Harlin, O.; Klement, B.; Franzem, M.; Wamhoff, J.; Tesch, H.; Rohrberg, R.; Marschner, N.

2013-01-01

389

Experience with intravenous ferric carboxymaltose in patients with iron deficiency anemia.  

PubMed

Erythropoiesis may be limited by absolute or functional iron deficiency or when chronic inflammatory conditions lead to iron sequestration. Intravenous iron may be indicated when oral iron cannot address the deficiency. Ferric carboxymaltose (FCM) is a nondextran iron preparation recently approved in the United States for intravenous treatment of iron deficiency anemia (IDA) in adult patients with intolerance or unsatisfactory response to oral iron or with nondialysis-dependent chronic kidney disease. The full dose is two administrations of up to 750 mg separated by at least 7 days (up to 1500 mg total). FCM can be injected in 7-8 min or diluted in saline for slower infusion. The efficacy and safety of this dose was established in two prospective trials that randomized over 3500 subjects, 1775 of whom received FCM. One trial showed similar efficacy of FCM to an approved intravenous iron regimen (1000 mg of iron sucrose) in 2500 subjects with chronic kidney disease and additional cardiovascular risk factors. The other trial showed superior efficacy of FCM to oral iron in subjects with IDA due to various etiologies (e.g. gastrointestinal or uterine bleeding). In these trials, there was no significant difference between FCM and comparator with respect to an independently adjudicated composite safety endpoint, including death, myocardial infarction, or stroke. A database of 5799 subjects exposed to FCM provided a safety profile acceptable for regulatory approval. Mechanistic studies demonstrated that the transient, asymptomatic reduction in serum phosphate observed following FCM administration results from induction of fibroblast growth factor 23, which in turn induces renal phosphate excretion. An elevated hepcidin level may identify patients with IDA who will not respond to oral iron but will respond to FCM. The ability to administer FCM in two rapid injections or infusions will likely be viewed favorably by patients and healthcare providers. PMID:24688754

Bregman, David B; Goodnough, Lawrence T

2014-04-01

390

Safety and tolerability of intravenous ferric carboxymaltose in patients with iron deficiency anemia.  

PubMed

There is limited safety information about ferric carboxymaltose (FCM), a new intravenous iron preparation. This randomized, crossover study compared the safety and tolerability of double-blinded intravenous doses of FCM or placebo in patients with iron deficiency anemia. Subjects (559) with iron deficiency anemia received a dose of either FCM (15 mg/kg, maximum 1000 mg) over 15 minutes or placebo on day 0. On day 7, subjects received the other agent. Safety evaluations were performed on days 7 and 14. The primary endpoint was the incidence of treatment-emergent adverse events during each 7-day study period. During the first 24 hours and during the 7-day treatment period, at least one treatment-emergent adverse event was experienced by 15.0% and 29.3% of subjects after FCM and 11.4% and 19.7% after placebo, respectively. Most were classified as Grade 1 or 2. Six subjects had Grade 3 treatment-emergent adverse events after FCM and 9 subjects after placebo. One subject had a Grade 4, and 1 subject had a Grade 5 treatment-emergent adverse event, but neither was considered study drug-related. During the first 24 hours of the treatment period, drug-related adverse events were reported in 9.3% of subjects receiving FCM and 4.8% receiving placebo. Of drug-related Grade 3 events, 4 subjects received FCM and 5 subjects received placebo. Administration of FCM (15 mg/kg, maximum of 1000 mg) over 15 minutes was well tolerated and associated with minimal risk of adverse reactions in patients with iron deficiency anemia. PMID:19888949

Bailie, George R; Mason, Nancy A; Valaoras, Thomas G

2010-01-01

391

Iron-reducing bacteria accumulate ferric oxyhydroxide nanoparticle aggregates that may support planktonic growth  

SciTech Connect

Iron-reducing bacteria (FeRB) play key roles in anaerobic metal and carbon cycling and carry out biogeochemical transformations that can be harnessed for environmental bioremediation. A subset of FeRB require direct contact with Fe(III) bearing minerals for dissimilatory growth, yet these bacteria must move between mineral particles. Further, they proliferate in planktonic consortia during biostimulation experiments. Thus, a key question is how such organisms can sustain growth under these conditions. Here we characterized planktonic microbial communities sampled from an aquifer in Rifle, Colorado, USA close to the peak of iron reduction following in situ acetate amendment. Samples were cryo-plunged on site and subsequently examined using correlated 2- and 3- dimensional cryogenic transmission electron microscopy (cryo-TEM) and scanning transmission X-ray microscopy (STXM). Most cells had their outer membranes decorated with up to 150 nm diameter aggregates composed of a few nm wide amorphous, Fe-rich nanoparticles. Fluorescent in situ hybridization of lineage-specific probes applied to rRNA of cells subsequently imaged via cryo-TEM identified Geobacter spp., a well studied group of FeRB. STXM results at the Fe L2,3 absorption edges indicate that nanoparticle aggregates contain a variable mixture of Fe(II)-Fe(III), and are generally enriched in Fe(III). Geobacter bemidjiensis cultivated anaerobically in the laboratory on acetate and hydrous ferric oxyhydroxides also accumulated mixed valence nanoparticle aggregates. In field-collected samples, FeRB with a wide variety of morphologies were associated with nano-aggregates, indicating that cell-surface Fe(III) accumulation may be a general mechanism by which FeRB can grow while in planktonic suspension.

Luef, Birgit; Fakra, Sirine C.; Csencsits, Roseann; Wrighton, Kelly C.; Williams, Kenneth H.; Wilkins, Michael J.; Downing, Kenneth H.; Long, Philip E.; Comolli, Luis R.; Banfield, Jillian F.

2013-02-04

392

Iron-reducing bacteria accumulate ferric oxyhydroxide nanoparticle aggregates that may support planktonic growth  

PubMed Central

Iron-reducing bacteria (FeRB) play key roles in anaerobic metal and carbon cycling and carry out biogeochemical transformations that can be harnessed for environmental bioremediation. A subset of FeRB require direct contact with Fe(III)-bearing minerals for dissimilatory growth, yet these bacteria must move between mineral particles. Furthermore, they proliferate in planktonic consortia during biostimulation experiments. Thus, a key question is how such organisms can sustain growth under these conditions. Here we characterized planktonic microbial communities sampled from an aquifer in Rifle, Colorado, USA, close to the peak of iron reduction following in situ acetate amendment. Samples were cryo-plunged on site and subsequently examined using correlated two- and three-dimensional cryogenic transmission electron microscopy (cryo-TEM) and scanning transmission X-ray microscopy (STXM). The outer membranes of most cells were decorated with aggregates up to 150?nm in diameter composed of ?3?nm wide amorphous, Fe-rich nanoparticles. Fluorescent in situ hybridization of lineage-specific probes applied to rRNA of cells subsequently imaged via cryo-TEM identified Geobacter spp., a well-studied group of FeRB. STXM results at the Fe L2,3 absorption edges indicate that nanoparticle aggregates contain a variable mixture of Fe(II)–Fe(III), and are generally enriched in Fe(III). Geobacter bemidjiensis cultivated anaerobically in the laboratory on acetate and hydrous ferric oxyhydroxides also accumulated mixed-valence nanoparticle aggregates. In field-collected samples, FeRB with a wide variety of morphologies were associated with nano-aggregates, indicating that cell surface Fe(III) accumulation may be a general mechanism by which FeRB can grow while in planktonic suspension. PMID:23038172

Luef, Birgit; Fakra, Sirine C; Csencsits, Roseann; Wrighton, Kelly C; Williams, Kenneth H; Wilkins, Michael J; Downing, Kenneth H; Long, Philip E; Comolli, Luis R; Banfield, Jillian F

2013-01-01

393

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

PubMed Central

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

2014-01-01

394

A Visual Insight into the Oxidation of Sulfide Minerals During Bioleaching and Chemical Leaching of a Complex Ore  

Microsoft Academic Search

A scanning electron microscope (SEM) study was performed to provide a visual insight into the oxidation patterns of sulfide minerals during chemical and bacterial leaching of a complex ore for 3 days. The mineral grains were studied under SEM before and after bacterial and chemical leaching with or without the addition of ferrous iron to generate ferric iron in situ

H. Deveci; T. Ball

2010-01-01

395

Effects of Shaking Time on Long?term Phosphorus Desorption using Dialysis Membrane Tubes filled with Hydrous Iron Oxide  

Microsoft Academic Search

The use of dialysis membrane tubes filled with hydrous ferric oxide (DMT?HFO) solution has recently been reported as an effective way to characterize phosphorus (P) desorption over a long term in laboratory studies. However, the DMT?HFO method, similar to other soil tests, exploits 100% of the sample volume, which is much more than what the plant roots can exploit under

A. M. Taddesse; A. S. Claassens; P. C. de Jager

2008-01-01

396

Comparative evaluation of Ferric Sulfate, Electrosurgical and Diode Laser on human primary molars pulpotomy: an “in-vivo” study  

PubMed Central

Background and aims: Despite modern advances in the prevention of dental caries and increased understanding of the importance of maintaining the natural primary dentition, many teeth are still lost prematurely. This can lead to malocclusion with aesthetic, phonetic and functional problems that may be transient or permanent. Therefore, maintaining the integrity and health of the oral tissues is the primary objective of pulp treatment. Pulpotomy has remained an acceptable and mainstay treatment in preserving the vitality of primary tooth and prolonging its life till the permanent successor erupts. Various materials and techniques are available for pulpotomy on primary molars; all with some advantages and disadvantages. The present study was carried out on 45 primary molars to evaluate and compare the clinical and radiographic success of diode laser, electrosurgical and ferric sulfate pulpotomy over a period of 9 months. Materials (Subjects) and Methods: The forty five primary molars were randomly and equally divided into three treatment groups which were as follows: Group A: 15 primary molars treated with 15.5% Ferric sulfate Group B: 15 primary molars treated with electrosurgical unit and Group C: 15 primary molars treated with diode laser. All teeth in three categories were followed up clinically and radiographically at 1, 3, 6 and 9 months post treatment and the findings were recorded on the prepared proforma Results: Clinically, 86.6% success rate was found in ferric sulfate group whereas 100% success rate was found in electrosurgical and diode laser groups. Radiographically, 80% success rate was found in all the three groups at the end of 9 months with internal resorption being the most common cause of failure after pulpotomy. Conclusions: Thus, electrosurgery and diode lasers appear to be acceptable alternative to pharmacotherapeutic pulpotomy agents. PMID:24771970

Yadav, P; Indushekar, KR; Saraf, BG; Sheoran, N; Sardana, D

2014-01-01

397

The influence of ferric iron and hydrogen on Fe-Mg interdiffusion in ferropericlase ((Mg,Fe)O) in the lower mantle  

NASA Astrophysics Data System (ADS)

Both ferric iron (Fe3+) and hydrogen (H+) have important influence on several transport properties of minerals such as diffusion. We determined the influence of Fe3+ and H+ on Fe-Mg interdiffusion in (Mg,Fe)O at 1,673-1,873 K and 5-24 GPa under the anhydrous and hydrous conditions using the diffusion couple technique. The diffusion couples consist of single crystals of ferropericlase ((Mg,Fe)O) and periclase (MgO) with Mg/(Mg + Fe) ratios ranging from 0.44 to 1.0. The oxygen fugacity was controlled by the following assemblages of metal and oxide: Fe-FeO, Ni-NiO, Mo-MoO2, and Re-ReO2. After the diffusion experiments, hydrogen (H+) concentrations were measured using the FTIR spectroscopy. Fe3+ concentrations were measured using the flank method. Under the conditions investigated, Fe-Mg interdiffusivity increases strongly with Fe3+ and modestly with H+ and the influence of H+ relative to that of Fe3+ on Fe-Mg interdiffusion decreases with temperature. Our results show that, under both anhydrous and hydrous conditions, the dominant defect responsible for diffusion is the same suggesting that H+ enhances Fe-Mg interdiffusivity by enhancing the mobility of vacancies at the M-site. Our results indicate that the influence of Fe3+ likely dominates at temperatures expected for the normal lower mantle conditions (T > 1,900 K), while the influence of both Fe3+ and H+ is important at lower temperature environments such as near the subduction zone. We also estimated the vacancy diffusivity based on Fe-Mg interdiffusion and vacancy concentration estimated from the charge neutrality condition with Fe3+. Both Fe-Mg interdiffusivity and vacancy diffusivities are reasonably consistent with values estimated from previous experimental and theoretical studies.

Otsuka, Kazuhiko; Karato, Shun-ichiro

2014-11-01

398

Correlations among parameters that describe low-spin ferric heme complexes.  

PubMed

The g values from low-spin ferric hemes can be related through the t2g hole model to rhombic (V/lambda) and tetragonal (delta/lambda) ligand field components and to the lowest Kramer's doublet energy (E/lambda). The latter is also a measure of unpaired electron sharing among the iron 3d (t2g) orbitals. For a series of ligands (X), there is a monotonic increase in myoglobin complex (Mb . X) [E/lambda] values with nonheme hexacoordinate metal complex (M . X6) [eg-t2gPg] orbital separations. As the aqueous solution pKa values of the sulfurous or nitrogenous ligands in model heme complexes increase, values of V/lambda and delta/lambda increase linearly, but those of [E/lambda] decrease linearly. The greater the electron-acceptor ability of the ligand, as suggested by its position in the spectrochemical series or its pKa, the more the unpaired electron sharing among the heme t2g orbitals increases. The rate of change of [E/lambda] with V/lambda and the pKa is different with sulfurous and nitrogenous ligands, and the magnitude of both rates increases with two sulfurs less than sulfur and nitrogen less than two nitrogens bound to the heme. The maximum magnitude of this rate with V/lambda for cytochrome P-450 is four times less than that for myoglobin, which may explain, in part, the differences in ligand binding between these two hemeproteins. The perturbation of [E/lambda], V/lambda, and delta/lambda induced by strain of iron-ligand bonds is quantitated for several hemeproteins and heme models. In addition, energy level comparisons suggest that the largest-magnitude g value falls approximately along the iron-chlorin ring normal. This suggestion implies that the electron distribution of the iron at the catalytic sites of cytochrome P-450 and certain chlorin-containing enzymes is in some way similar, but distinct from that at the transport site of myoglobin. PMID:6091554

Muhoberac, B B

1984-09-01

399

The new generation of intravenous iron: chemistry, pharmacology, and toxicology of ferric carboxymaltose.  

PubMed

An ideal preparation for intravenous iron replacement therapy should balance effectiveness and safety. Compounds that release iron rapidly tend to cause toxicity, while large molecules can induce antibody formation and cause anaphylactic reactions. There is therefore a need for an intravenous iron preparation that delivers appropriate amounts of iron in a readily available form but with minimal side effects and thus with an excellent safety profile. In this paper, a review is given on the chemistry, pharmacology, and toxicology of ferric carboxymaltose (FCM, Ferinject), a stable and robust complex formulated as a colloidal solution with a physiological pH. The complex is gradually taken up mainly from the hepatic reticulo-endothelial system (RES), followed by effective delivery of iron to the endogeneous transport system for the haem synthesis in new erythrocytes, as shown in studies on the pharmacodynamics and pharmacokinetics with radio-labelled FCM. Studies with radio-labelled FCM also demonstrated a barrier function of the placenta and a low transfer of iron into the milk of lactating rats. Safety pharmacology studies indicated a favourable profile with regard to cardiovascular, central nervous, respiratory, and renal toxicity. A high maximum non-lethal dose was demonstrated in the single-dose toxicity studies. Furthermore, based on the No-Observed-Adverse-Effect-Levels (NOAELs) found in repeated-dose toxicity studies and on the cumulative doses administered, FCM has good safety margins. Reproductive and developmental toxicity studies did not reveal any direct or indirect harmful effects. No genotoxic potential was found in in vitro or in vivo studies. Moreover, antigenicity studies showed no cross-reactivity of FMC with anti-dextran antibodies and also suggested that FCM does not possess sensitizing potential. Lastly, no evidence of irritation was found in local tolerance studies with FCM. This excellent toxicity profile and the high effectiveness of FCM allow the administration of high doses as a single infusion or bolus injection, which will enhance the cost-effectiveness and convenience of iron replacement therapy. In conclusion, FCM has many of the characteristics of an ideal intravenous iron preparation. PMID:20648926

Funk, Felix; Ryle, Peter; Canclini, Camillo; Neiser, Susann; Geisser, Peter

2010-01-01

400

Cloning, expression and immunogenicity of ferric enterobactin binding protein Fep B from Escherichia coli O157:H7  

Microsoft Academic Search

The gene coding for ferric enterobactin binding protein from E. coli O157:H7 was amplifi ed. This gene was cloned and expressed as C-terminal His (6)-tagged protein. The SDS-PAGE analysis of\\u000a the total protein revealed only two distinct bands, with molecular masses of 31kDa and 34kDa. The Ni-NTA chromatography purifi\\u000a ed FepB and the osmotically shocked periplasmic fraction of IPTG induced

Majid Alipour; Seyed Latif Mousavi Gargari; Iraj Rasooli

2009-01-01

401

Influence of organic matter on the transport of Cryptosporidium parvum oocysts in a ferric oxyhydroxide-coated quartz sand saturated porous medium  

USGS Publications Warehouse

To assess the effect of organic matter on the transport of Cryptosporidium parvum oocysts in a geochemically heterogeneous saturated porous medium, we measured the breakthrough and collision efficiencies of oocysts as a function of dissolved organic matter concentration in a flow-through column containing ferric oxyhydroxide-coated sand. We characterized the surface properties of the oocysts and ferric oxyhydroxide-coated sand using microelectrophoresis and streaming potential, respectively, and the amount of organic matter adsorbed on the ferric oxyhydroxide-coated sand as a function of the concentration of dissolved organic matter (a fulvic acid isolated from Florida Everglades water). The dissolved organic matter had no significant effect on the zeta potential of the oocysts. Low concentrations of dissolved organic matter were responsible for reversing the charge of the ferric oxyhydroxide-coated sand surface from positive to negative. The charge reversal and accumulation of negative charge on the ferric oxyhydroxide-coated sand led to increases in oocyst breakthrough and decreases in oocyst collision efficiency with increasing dissolved organic matter concentration. The increase in dissolved organic matter concentration from 0 to 20 mg L-1 resulted in a two-fold decrease in the collision efficiency. ?? 2009 Elsevier Ltd.

Abudalo, R.A.; Ryan, J.N.; Harvey, R.W.; Metge, D.W.; Landkamer, L.

2010-01-01

402

Effect of ferric oxyhydroxide grain coatings on the transport of bacteriophage PRD1 and Cryptosporidium parvum oocysts in saturated porous media  

USGS Publications Warehouse

To test the effect of geochemical heterogeneity on microorganism transport in saturated porous media, we measured the removal of two microorganisms, the bacteriophage PRD1 and oocysts of the protozoan parasite Cryptosporidium parvum, in flow-through columns of quartz sand coated by different amounts of a ferric oxyhydroxide. The experiments were conducted over ranges of ferric oxyhydroxide coating fraction of ?? = 0-0.12 for PRD1 and from ?? = 0-0.32 for the oocysts at pH 5.6-5.8 and 10-4 M ionic strength. To determine the effect of pH on the transport of the oocysts, experiments were also conducted over a pH range of 5.7-10.0 at a coating fraction of ?? = 0.04. Collision (attachment) efficiencies increased as the fraction of ferric oxyhydroxide coated quartz sand increased, from ?? = 0.0071 to 0.13 over ?? = 0-0.12 for PRD1 and from ?? = 0.059 to 0.75 over ?? = 0-0.32 for the oocysts. Increasing the pH from 5.7 to 10.0 resulted in a decrease in the oocyst collision efficiency as the pH exceeded the expected point of zero charge of the ferric oxyhydroxide coatings. The collision efficiencies correlated very well with the fraction of quartz sand coated by the ferric oxyhydroxide for PRD1 but not as well for the oocysts. ?? 2005 American Chemical Society.

Abudalo, R. A.; Bogatsu, Y. G.; Ryan, J. N.; Harvey, R. W.; Metge, D. W.; Elimelech, M.

2005-01-01

403

A novel role of the ferric reductase Cfl1 in cell wall integrity, mitochondrial function, and invasion to host cells in Candida albicans.  

PubMed

Candida albicans is an important opportunistic pathogen, causing both superficial mucosal infections and life-threatening systemic diseases. Iron acquisition is an important factor for pathogen-host interaction and also a significant element for the pathogenicity of this organism. Ferric reductases, which convert ferric iron into ferrous iron, are important components of the high-affinity iron uptake system. Sequence analyses have identified at least 17 putative ferric reductase genes in C. albicans genome. CFL1 was the first ferric reductase identified in C. albicans. However, little is known about its roles in C. albicans physiology and pathogenicity. In this study, we found that disruption of CFL1 led to hypersensitivity to chemical and physical cell wall stresses, activation of the cell wall integrity (CWI) pathway, abnormal cell wall composition, and enhanced secretion, indicating a defect in CWI in this mutant. Moreover, this mutant showed abnormal mitochondrial activity and morphology, suggesting a link between ferric reductases and mitochondrial function. In addition, this mutant displayed decreased ability of adhesion to both the polystyrene microplates and buccal epithelial cells and invasion of host epithelial cells. These findings revealed a novel role of C. albicans Cfl1 in maintenance of CWI, mitochondrial function, and interaction between this pathogen and the host. PMID:25130162

Yu, Qilin; Dong, Yijie; Xu, Ning; Qian, Kefan; Chen, Yulu; Zhang, Biao; Xing, Laijun; Li, Mingchun

2014-11-01

404

Arsenic Release from Natural and Anthropogenic Metal (Hydr)Oxide Sorbents  

NASA Astrophysics Data System (ADS)

Arsenic is a common constituent of soils and minerals throughout the world and is, at a global scale, arguably the most serious inorganic drinking water contaminant. The talk will focus on the results of studies to elucidate the biogeochemical conditions that lead to enhanced release and mobility of arsenic in aqueous streams. It will be suggested that when arsenic is (relatively) stably bound to metal (hydr)oxides in an oxic environment, the redox shift conditions which lead to arsenic mobilization in natural ground waters are also present in many of the locations where the arsenic-bearing residuals from water treatment processes are disposed. In oxic environments a large fraction of the arsenic is commonly present as an adsorbed species associated with metal (hydr)oxides, particularly ferric (hydr)oxides. Likewise, ferric (hydr)oxide based sorbents are by far the most common method utilized for removing arsenic from drinking water. It has been known for many years that the mobilization of arsenic from these materials most dramatically occurs when moderate to low redox conditions (-100 to -300 mV) occur and this release has been attributed to the reductive dissolution of the ferric sorbent. However, our and others' recent work suggests that most of the arsenic release in such conditions is decoupled from the iron release and the presence or absence of the reductive dissolution of ferric (hydr)oxides has little bearing on the overall magnitude of arsenic mobilization. There are many practical ramifications of this result, one of the simplest is that if arsenic is sorbed to a non- redox sensitive solid surface (of say a zirconium or lanthanum oxide), rather than an iron surface, it will not reduce the lability of arsenic when the solid is exposed to reducing conditions. Furthermore, when reducing conditions are imposed on ferric (hydr)oxide sorbent systems, the reductive dissolution of ferric species feeds the precipitation of mixed iron and ferrous iron solids whose rate of formation, degree of crystallinity, and sorptive capacity is a function of the concentration of arsenic species in the system.

Ela, W. P.; Sįez, E.

2008-12-01

405

Oxidation of basaltic tephras: Influence on reflectance in the 1 micron region  

NASA Technical Reports Server (NTRS)

As part of a ongoing study into the products of hydrovolcanism, tuffs were examined from the Cerro Colorado and Pavant Butte tuff cones. The former resides in the northeastern corner of the Pinacate Volcanic Field in Sonara, Mexico and the latter is in the Black Rock Desert of southern Utah. Numerous samples were collected and many of these had their Vis/IR reflectance measured. It seems likely that in the palagonite tuffs there is a combination of nanocrystalline ferric oxide phases contributing to the UV absorption edge, but not to the 1 micron band, plus more crystalline ferric oxides which do contribute to that band as well as ferrous iron within unaltered sideromelane which is skewing the band center to longer wavelengths. This work has implications for the study of Mars. The present work indicates that when ferrous and ferric iron phases are both present, their combined spectral contribution is a single band in the vicinity of 1 micron. The center, depth, and width of that feature has potential to be used to gauge the relative proportions of ferrous and ferric iron phases.

Farrand, William H.; Singer, Robert B.

1991-01-01

406

First-principles study of spin transition and seismic properties of ferric iron-bearing post-perovskite with oxygen vacancy  

NASA Astrophysics Data System (ADS)

The spin states, elastic properties and seismic velocities of ferric iron-bearing post-perovskite MgSiO3 (pPv) with single oxygen vacancy [Mg8(Si6,Fe2)O23 and Mg16(Si14,Fe2)O47] were calculated by first principles based on density functional theory. The effects of ferric iron and oxygen vacancy on seismic waves were studied for the host pPv subjected to a hydrostatic pressure. Calculations revealed a new spin transition from intermediate-spin to low-spin states with increasing pressure. As a result, the volume was reduced and the elastic constants were modified, producing a clear decrease in the seismic velocities of both compressive wave and shear wave due to the reduction of bulk modulus and shear modulus. The ferric iron and oxygen vacancy also had a minor effect on wave anisotropy.

Gao, Benzhou; He, Kaihua; Chen, Qili; Wang, Xicheng; Wang, Qingbo; Wan, Miao; Ji, Guangfu

2014-09-01

407

Influence of the addition of sulphate and ferric ions in a methanogenic anaerobic packed-bed reactor treating gasoline-contaminated water.  

PubMed

Benzene, toluene and xylene (BTX) are relatively soluble aromatic compounds of gasoline. Gasoline storage tank leakages generally lead to an extensive contamination of groundwater. In the natural environment for instance, these compounds might be biodegraded under a variety of reducing potentials. The objective of this work was to examine the influence of the addition of sulphate and Fe(OH)3 in a methanogenic horizontal-flow anaerobic immobilized-biomass reactor treating gasoline-contaminated water. Three different conditions were evaluated: methanogenic, sulphidogenic and sulphidogenic with the addition of ferric ions. Methanogenic condition showed the higher BTX degradation rates and the addition of sulphate negatively affected BTX removal rates with the production of H2S. However, the addition of ferric ions resulted in the precipitation of sulphur, improving BTX degradation by the consortium. Metanosphaera sp., Methanosarcina barkeri and Methanosaeta concilii were identified in the consortium by means of 16S and directly related to the addition of ferric ions. PMID:16939094

Fernandes, B S; Chinalia, F A; Sarti, A; Silva, A J; Foresti, E; Zaiat, M

2006-01-01

408

BIOGEOCHEMICAL PROCESSES CONTROLLING ARSENIC SPECIATION AND BIOTRANSFORMATION IN GRANULAR FERRIC HYDROXIDE COATED SAND  

EPA Science Inventory

Arsenic mobilization from solid phase Fe (III) hydroxides is an issue of concern, as water-borne arsenic can migrate into pristine environments, endangering aquatic and human life. In general, metal oxide (hydroxides) exerts a dominating effect on the fate and transport of arseni...

409

Manganese peroxidase from the basidiomycete Phanerochaete chrysosporium: spectral characterization of the oxidized states and the catalytic cycle  

Microsoft Academic Search

Manganese peroxidase (MnP), an extracellular heme enzyme from the lignin-degrading fungus Phanerochaete chrysosporium, catalyzes the Mn(II)-dependent oxidation of a variety of phenols. Herein, the authors spectroscopically characterize the oxidized states of MnP compounds I, II, and III and clarify the role of Mn in the catalytic cycle of the enzyme. Addition of 1 equiv of HāOā to the native ferric

Hiroyuki Wariishi; Lakshmi Akileswaran; Michael H. Gold

1988-01-01

410

Microwave Assisted Synthesis of Iron(III) Oxyhydroxides/Oxides Characterized Using Transmission Electron Microscopy, X-ray Diffraction, and X-ray Absorption Spectroscopy  

PubMed Central

Microwave assisted synthesis of iron oxide/oxyhydroxide nanophases was conducted using iron(III) chloride titrated with sodium hydroxide at seven different temperatures from 100°C to 250°C with pulsed microwaves. From the XRD results, it was determined that there were two different phases synthesized during the reactions which were temperature dependent. At the lower temperatures, 100°C and 125°C, it was determined that an iron oxyhydroxide chloride was synthesized. Whereas, at higher temperatures, at 150°C and above, iron(III) oxide was synthesized. From the XRD, we also determined the FWHM and the average size of the nanoparticles using the Scherrer equation. The average size of the nanoparticles synthesized using the experimental conditions were 17, 21, 12, 22, 26, 33, 28 nm, respectively for the reactions from 100°C to 250°C. The particles also had low anisotropy indicating spherical nanoparticles, which was later confirmed using TEM. Finally, XAS studies show that the iron present in the nanophase was present as iron(III) coordinated to six oxygen atoms in the first coordination shell. The higher coordination shells also conform very closely to the ideal or bulk crystal structures. PMID:20161181

Parsons, J.G.; Luna, C.; Botez, C.E.; Elizalde, J.; Gardea-Torresdey, J.L.

2009-01-01

411

Synthesis of alumina powder by the urea-glycine-nitrate combustion process: a mixed fuel approach to nanoscale metal oxides  

NASA Astrophysics Data System (ADS)

Main objective of present work is to study the efficiency of mixed fuel towards solution combustion synthesis of alumina powder, which otherwise prepared by single fuel and study of properties of final product with mixed fuel approach. Two different fuels, glycine and urea, along with aluminium nitrates have been used to prepare nanophase alumina powder. Different fuel to oxidizer ratios and different percentage combination of two fuels were used to prepare six samples. In all samples, nanoscale particle size obtained. Parameter which continuously changes the results of various characterisations is percentage combination of two fuels. In case where percentage of urea is higher than glycine reaction takes place with high exothermicity and hence crystallinity in product phase, whereas glycine promotes amorphous character. With mixed fuel approach, crystallinity can be enhanced easily, by calcinations of powder product at low temperature, because due to mixed urea and glycine, there is already some fraction of crystallinity observed. Overall mixed fuel approach has ability to produce nanophase alumina powder with wide range of particles size.

Sharma, Amit; Rani, Amita; Singh, Ajay; Modi, O. P.; Gupta, Gaurav K.

2014-03-01

412

Photocatalytic oxidation of methyl orange in water phase by immobilized TiO2-carbon nanotube nanocomposite photocatalyst  

NASA Astrophysics Data System (ADS)

We developed an immobilized carbon nanotube (CNT)-titanium dioxide (TiO2) heterostructure material for the photocatalytic oxidation of methyl orange in aqueous phase. The catalyst material was prepared via sol-gel method using multi-walled CNTs grown on graphite substrate as carriers. The multi-walled CNTs were synthesized from thermal decomposing of hydrocarbon gas directly on thin graphite plate, forming immobilized 3-dimensional network of CNTs. The nanophase TiO2 was synthesized coating on CNTs to form "coral"-shaped nanocomposite 3-dimensional network on graphite substrate, thus bringing effective porous structure and high specific surface area, and possessing the merit of dispersive powder photocatalysts, which is the fully available surface area, while adapting the requirement for clean and convenient manipulation as an immobilized photocatalyst. Moreover, the CNT-TiO2 heterostructure reduced the electron-hole pair recombination rate and enhanced the photoabsorption and the adsorption ability, resulting in elevating the photocatalysis efficiency. These synergistic effects due to the hybrid nature of the materials and interphase interaction greatly improved the catalytic activity, and demonstrated superior photocatalytic performances. Our work can be a significant inspiration for developing hybrid nano-phase materials to realize sophisticated functions, and bear tremendous significance for the development and applications of semiconductor nano-materials.

Dong, Yinmao; Tang, Dongyan; Li, Chensha

2014-03-01

413

Novel electrochemical-enzymatic model which quantifies the effect of the solution Eh on the kinetics of ferrous iron oxidation with Acidithiobacillus ferrooxidans.  

PubMed

The influence of solution Eh on the rate of ferrous iron oxidation by Acidithiobacillus ferrooxidans is characterized. The experimental approach was based on the use of a two-chamber bioelectrochemical cell, which can determine the ferrous iron oxidation rate at controlled potential. Results enabled the formulation of a novel kinetic model, which incorporates the effect of solution Eh in an explicit form but still integrates the effect of ferrous iron concentration and ferric inhibition. The results showed that at Eh values below 650 mV (standard hydrogen electrode, SHE) the bacterial oxidative activity is mainly dependent on ferrous iron concentration. At Eh values between 650 and 820 mV (SHE) the oxidation rate is mainly controlled by ferric inhibition. Over 820 mV (SHE) the bacterial oxidative activity is strongly inhibited by the Eh increase, being completely inhibited at Eh = 840 mV (SHE). PMID:12226860

Meruane, G; Salhe, C; Wiertz, J; Vargas, T

2002-11-01

414

Performance evaluation of ALCAN-AASF50-ferric coated activated alumina and granular ferric hydroxide (GFH) for arsenic removal in the presence of competitive ions in an active well :Kirtland field trial - initial studies.  

SciTech Connect

This report documents a field trial program carried out at Well No.15 located at Kirtland Air Force Base, Albuquerque, New Mexico, to evaluate the performance of two relatively new arsenic removal media, ALCAN-AASF50 (ferric coated activated alumina) and granular ferric hydroxide (US Filter-GFH). The field trial program showed that both media were able to remove arsenate and meet the new total arsenic maximum contaminant level (MCL) in drinking water of 10 {micro}g/L. The arsenate removal capacity was defined at a breakthrough effluent concentration of 5 {micro}g/L arsenic (50% of the arsenic MCL of 10 {micro}g/L). At an influent pH of 8.1 {+-} 0.4, the arsenate removal capacity of AASF50 was 33.5 mg As(V)/L of dry media (29.9 {micro}g As(V)/g of media on a dry basis). At an influent pH of 7.2 {+-} 0.3, the arsenate removal capacity of GFH was 155 mg As(V)/L of wet media (286 {micro}g As(V)/g of media on a dry basis). Silicate, fluoride, and bicarbonate ions are removed by ALCAN AASF50. Chloride, nitrate, and sulfate ions were not removed by AASF50. The GFH media also removed silicate and bicarbonate ions; however, it did not remove fluoride, chloride, nitrate, and sulfate ions. Differences in the media performance partly reflect the variations in the feed-water pH between the 2 tests. Both the exhausted AASF50 and GFH media passed the Toxicity Characteristic Leaching Procedure (TCLP) test with respect to arsenic and therefore could be disposed as nonhazardous waste.

Neidel, Linnah L.; Krumhansl, James Lee; Siegel, Malcolm Dean; Khandaker, Nadim Reza

2006-01-01

415

Ferric reduction by iron-limited Chlamydomonas cells interacts with both photosynthesis and respiration  

Microsoft Academic Search

.   Iron limitation led to a large increase in extracellular ferricyanide (Fe[III]) reductase activity in cells of the green\\u000a alga Chlamydomonas reinhardtii Dangeard. Mass-spectrometric measurement of gas exchange indicated that ferricyanide reduction in the dark resulted in a\\u000a stimulation of respiratory CO2 production without affecting the rate of respiratory O2 consumption, consistent with the previously postulated activation of the oxidative

Harold G. Weger; George S. Espie

2000-01-01

416

Ferric sulphate\\/chloride leaching of zinc and minor elements from a sphalerite concentrate  

Microsoft Academic Search

Atmospheric leaching of a sphalerite concentrate in sulphate and chloride media was performed and the effect of several variables, such as solid\\/liquid ratio and oxidant (Fe(III)) concentration were investigated. The behaviour of minor elements, such as Cu, In, As, Sb, Bi, Sn and Pb, was also studied under different conditions. The results showed that using a solid\\/liquid ratio of 5%

Sķlvia M. C. Santos; Remķgio M. Machado; M. Joana N. Correia; M. Teresa A. Reis; M. Rosinda C. Ismael; Jorge M. R. Carvalho

2010-01-01

417

Nanophase and Composite Optical Materials  

NASA Technical Reports Server (NTRS)

This talk will focus on accomplishments, current developments, and future directions of our work on composite optical materials for microgravity science and space exploration. This research spans the order parameter from quasi-fractal structures such as sol-gels and other aggregated or porous media, to statistically random cluster media such as metal colloids, to highly ordered materials such as layered media and photonic bandgap materials. The common focus is on flexible materials that can be used to produce composite or artificial materials with superior optical properties that could not be achieved with homogeneous materials. Applications of this work to NASA exploration goals such as terraforming, biosensors, solar sails, solar cells, and vehicle health monitoring, will be discussed.

2003-01-01

418

Iron oxide/hydroxide nanoparticles with negatively charged shells show increased uptake in Caco-2 cells.  

PubMed

The absorption of commonly used ferrous iron salts from intestinal segments at neutral to slightly alkaline pH is low, mainly because soluble ferrous iron is easily oxidized to poorly soluble ferric iron and because ferrous iron, but not ferric iron, is carried by the divalent metal transporter DMT-1. Moreover, ferrous iron frequently causes gastrointestinal side effects. Iron hydroxide nanoparticles with neutral and hydrophilic carbohydrate shells are alternatively used to ferrous salts. In these formulations gastrointestinal side effects are rare because hundreds of ferric iron atoms are safely packed in nanoscaled cores surrounded by the solubilizing shell; nevertheless, iron bioavailability is even worse compared to ferrous salts. In this study the cell uptake of iron hydroxide and iron oxide nanoparticles (FeONP) with negatively charged shells of different chemical types and sizes was compared to the uptake of those with neutral hydrophilic shells, ferrous sulfate and ferric chloride. The nanoparticle uptake was measured in Caco-2 cells with the iron detecting ferrozine method and visualized by transmission electron microscopy. The toxicity was evaluated using the MTT assay. For nanoparticles with a negatively charged shell the iron uptake was about 40 times higher compared to those with neutral hydrophilic carbohydrate shell or ferric chloride and in the same range as ferrous sulfate. However, in contrast to ferrous sulfate, nanoparticles with negatively charged shells showed no toxicity. Two different uptake mechanisms were proposed: diffusion for hydroxide nanoparticles with neutral hydrophilic shell and adsorptive endocytosis for nanoparticles with negatively charged shells. It needs to be determined whether iron hydroxide nanoparticles with negatively charged shells also show improved bioavailability in iron-deficient patients compared to iron hydroxide nanoparticles wi